research
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Controlling 3D Behavior of Biological Cells Using Laser Holographic Techniques
A research team led by Professor YongKeun Park of the Physics Department at KAIST has developed an optical manipulation technique that can freely control the position, orientation, and shape of microscopic samples having complex shapes. The study has been published online in Nature Communications on May 22.
Conventional optical manipulation techniques called “optical tweezers,” have been used as an invaluable tool for exerting micro-scale force on microscopic particles and manipulating three-dimensional (3-D) positions of particles. Optical tweezers employ a tightly-focused laser whose beam diameter is smaller than one micrometer (1/100 of hair thickness), which can generate attractive force on neighboring microscopic particles moving toward the beam focus. Controlling the positions of the beam focus enabled researchers to hold the particles and move them freely to other locations so they coined the name “optical tweezers,” and have been widely used in various fields of physical and biological studies.
So far, most experiments using optical tweezers have been conducted for trapping spherical particles because physical principles can easily predict optical forces and the responding motion of microspheres. For trapping objects having complicated shapes, however, conventional optical tweezers induce unstable motion of such particles, and controllable orientation of such objects is limited, which hinder controlling the 3-D motion of microscopic objects having complex shapes such as living cells.
The research team has developed a new optical manipulation technique that can trap complex objects of arbitrary shapes. This technique first measures 3-D structures of an object in real time using a 3-D holographic microscope, which shares the same physical principle of X-Ray CT imaging. Based on the measured 3-D shape of the object, the researchers precisely calculates the shape of light that can stably control the object. When the shape of light is the same as the shape of the object, the energy of the object is minimized, which provides the stable trapping of the object having the complicated shape.
Moreover, by controlling the shape of light to have various positions, directions, and shapes of objects, it is possible to freely control the 3-D motion of the object and make the object have a desired shape. This process resembles the generation of a mold for casting a statue having desired shape so the researchers coined the name of the present technique “tomographic mold for optical trapping (TOMOTRAP).” The team succeeded in trapping individual human red blood cells stably, rotating them with desired orientations, folding them in an L-shape, and assembling two red blood cells together to form a new structure. In addition, colon cancer cells having a complex structure could be stably trapped and rotated at desired orientations. All of which have been difficult to be realized by the conventional optical techniques.
Professor Park said, “Our technique has the advantage of controlling the 3-D motion of complex shaped objects without knowing prior information about their shape and optical characteristics, and can be applied in various fields including physics, optics, nanotechnology, and medical science.”
Dr. Kyoohyun Kim, the lead author of this paper, noted that this technique can induce controlled deformation of biological cells with desired shapes. “This approach can be also applied to real-time monitoring of surgical prognosis of cellular-level surgeries for capturing and deforming cells as well as subcellular organelles,” added Kim.
Figure 1. Concept of optical manipulation techniques
Figure 2. Experimental setup
Figure 3. Research results
2017.05.25 View 8842 -
Total Synthesis of Flueggenine C via an Accelerated Intermolecular Rauhut-Currier Reaction
The first total synthesis of dimeric securinega alkaloid (-)-flueggenine C was completed via an accelerated intermolecular Rauhut–Currier (RC) reaction. The research team led by Professor Sunkyu Han in the Department of Chemistry succeeded in synthesizing the natural product by reinventing the conventional RC reaction.
The total synthesis of natural products refers to the process of synthesizing secondary metabolites isolated from living organisms in the laboratory through a series of chemical reactions. Each stage of chemical reaction needs to be successful to produce the final target molecule, and thus the process requires high levels of patience and creativity. For that reason, the researchers working on natural products total synthesis are often called “molecular artists”.
Despite numerous reports on the total synthesis of monomeric securinegas, the synthesis of dimeric securinegas, whose monomeric units are connected by a putative enzymatic RC reaction, has not been reported to date.
The team used a Rauhut-Currier (RC) reaction, a carboncarbon bond forming a reaction between two Michael acceptors first reported by Rauhut and Currier in 1963, to successfully synthesize a dimeric natural product, flueggenine C. This new work featured the first application of an intermolecular RC reaction in total synthesis.
The conventional intermolecular RC reaction was driven non-selectively by a toxic nucleophilic catalyst at a high temperature of over 150°C and a highly concentrated reaction mixture, and thus has never been applied to natural products total synthesis. To overcome this long-standing problem, the research team placed a nucleophilic moiety at the γ-position of the enone derivative. As a result, the RC reaction could be induced by the simple addition of a base at ambient temperature and dilute solution, without the need of a nucleophilic catalyst. Using this newly discovered reactivity, the team successfully synthesized the natural product (-)-flueggenine C from commercially available amino acid derivative in 12 steps.
Professor Han said, “Our key finding regarding the remarkably improved reactivity and selectivity of the intermolecular RC reaction will serve as a significant stepping stone in allowing this reaction to be considered a practical and reliable chemical tool with broad applicability in natural products, pharmaceuticals, and materials syntheses. ”
This research was led by Ph.D. candidate Sangbin Jeon and was published in The Journal of the American Chemical Society (JACS) on May 10. This research was funded by KAIST start-up funds, HRHR (High-Risk High-Return), RED&B (Research, Education, Development & Business) projects, the National Research Foundation of Korea, and the Institute for Basic Science.
(Figure 1: Representative dimeric/oligomeric securinega alkaloids)
(Figure 2: Our reinvented Rauhut-Currier reaction)
(Figure 3: Total Synthesis of (-)-flueggenine C)
2017.05.23 View 9605 -
Parasitic Robot System for Turtle's Waypoint Navigation
A KAIST research team presented a hybrid animal-robot interaction called “the parasitic robot system,” that imitates the nature relationship between parasites and host.
The research team led by Professor Phil-Seung Lee of the Department of Mechanical Engineering took an animal’s locomotive abilities to apply the theory of using a robot as a parasite. The robot is attached to its host animal in a way similar to an actual parasite, and it interacts with the host through particular devices and algorithms.
Even with remarkable technology advancements, robots that operate in complex and harsh environments still have some serious limitations in moving and recharging. However, millions of years of evolution have led to there being many real animals capable of excellent locomotion and survive in actual natural environment.
Certain kinds of real parasites can manipulate the behavior of the host to increase the probability of its own reproduction. Similarly, in the proposed concept of a “parasitic robot,” a specific behavior is induced by the parasitic robot in its host to benefit the robot.
The team chose a turtle as their first host animal and designed a parasitic robot that can perform “stimulus-response training.” The parasitic robot, which is attached to the turtle, can induce the turtle’s object-tracking behavior through repeated training sessions.
The robot then simply guides it using LEDs and feeds it snacks as a reward for going in the right direction through a programmed algorithm. After training sessions lasting five weeks, the parasitic robot can successfully control the direction of movement of the host turtles in the waypoint navigation task in a water tank.
This hybrid animal–robot interaction system could provide an alternative solution of the limitations of conventional mobile robot systems in various fields. Ph.D. candidate Dae-Gun Kim, the first author of this research said that there are a wide variety of animals including mice, birds, and fish that could perform equally as well at such tasks. He said that in the future, this system will be applied to various exploration and reconnaissance missions that humans and robots find it difficult to do on their own.
Kim said, “This hybrid animal-robot interaction system could provide an alternative solution to the limitations of conventional mobile robot systems in various fields, and could also act as a useful interaction system for the behavioral sciences.”
The research was published in the Journal of Bionic Engineering April issue.
2017.05.19 View 10155 -
Study Identifies the Novel Molecular Signal for Triggering Septic Shock
Professor Seyun Kim’s team at the Department of Biological Sciences reported the mechanism by which cellular signaling transduction networks are precisely controlled in mediating innate immune responses, such as sepsis, by the enzyme IPMK (Inositol polyphosphate multikinase) which is essential for inositol biosynthesis metabolism.
In collaboration with Professor Hyun Seong Roh at Seoul National University, the study’s first author, Eunha Kim, a Ph.D. candidate in Department of Biological Sciences, performed a series of cellular, biochemical, and physiological experiments searching for the new function of IPMK enzymes in macrophages. The research findings were published in Science Advances on April 21.
Professor Kim’s team has been investigating various inositol metabolites and their biosynthesis metabolism for several years and has multilaterally identified the signaling actions of IPMK for controlling cellular growth and energy homeostasis.
This research showed that the specific deletion of IPMK enzymes in macrophages could significantly reduce levels of inflammation and increase survival rates in mice when they were challenged by microbial septic shock and endotoxins. This suggests a role for IPMK enzymes in mediating innate inflammatory responses that are directly related to a host’s defense against pathogenic bacterial infection.
The team further discovered that IPMK enzymes directly bind to TRAF6 proteins, a key player in immune signaling, thus protecting TRAF6 proteins from ubiquitination reactions that are involved in protein degradation. In addition, Kim and his colleagues successfully verified this IPMK-dependent immune control by employing short peptides which can specifically interfere with the binding between IPMK enzymes and TRAF6 proteins in macrophage cells.
This research revealed a novel function of IPMK enzymes in the fine tuning of innate immune signaling networks, suggesting a new direction for developing therapeutics targeting serious medical conditions such as neuroinflammation, type 2 diabetes, as well as polymicrobial sepsis that are developed from uncontrolled host immune responses. This research was funded by the Ministry of Science, ICT and Future Planning.
(Figure: Deletion of IPMK (inositol polyphosphate multikinase) in macrophages reduces the stability of TRAF6 protein which is the key to innate immune signaling, thereby blocking excessive inflammation in response to pathological bacterial infection.)
2017.05.11 View 9269 -
Gout Diagnostic Strip Using a Single Teardrop
A novel diagnostic strip for gout patients using a single teardrop has been announced by KAIST research team. This technology analyzes biological molecules in tears for a non-invasive diagnosis, significantly reducing the time and expense previously required for a diagnosis.
The research team under Professor Ki-Hun Jeong of the Department of Bio and Brain Engineering succeeded in developing an affordable and elaborate gout diagnostic strip by depositing metal nanoparticles on paper. This technology can not only be used in diagnostic medicine and drug testing, but also in various other areas such as field diagnoses that require prompt and accurate detection of a certain substance.
Gout induces pain in joints due to needle-shaped uric acid crystal build up. In general, therapeutic treatments exist to administer pain relief, stimulate uric acid discharge, and uric acid depressant. Such treatments work for temporary relief, but there have significant limitations. Thus, patients are required to regularly check uric acid concentrations, as well as control their diets. Therefore, simpler ways to measure uric acid would greatly benefit gout control and its prevention in a more affordable and convenient manner.
Existing gout diagnostic techniques include measuring uric acid concentrations from blood samples or observing uric acid crystals from joint synovial fluid under a microscope. These existing methods are invasive and time consuming. To overcome their limitations, the research team uniformly deposited gold nanoislands with nanoplasnomics properties on the surface of paper that can easily collect tears.
Nanoplasnomics techniques collect light on the surface of a metal nanostructure, and can be applied to disease and health diagnostic indicators as well as for genetic material detection. Further, metals such as gold absorb stronger light when it is irradiated, and thus can maximize light concentration on board surfaces while maintaining the properties of paper. The developed metal nanostructure production technology allows the flexible manufacturing of nanostructures on a large surface, which in turn allows flexible control of light concentrations.
The research team grafted surface-enhanced Raman spectroscopy on paper diagnostic strips to allow uric acid concentration measurements in teardrops without additional indicators. The measured concentration in teardrops can be compared to blood uric acid concentrations for diagnosing gout.
Professor Jeong explained, “Based on these research results, our strip will make it possible to conduct low-cost, no indicator, supersensitive biological molecule analysis and fast field diagnosis using tears.” He continued, “Tears, as well as various other bodily fluids, can be used to contribute to disease diagnosis and physiological functional research.”
Ph.D. candidate Moonseong Park participated in the research as the first author of the paper that was published in the online edition of ACS Nano on December 14, 2016. Park said, “The strip will allow fast and simple field diagnosis, and can be produced on a large scale using the existing semiconductor process.”
(Figure 1. Optical image of paper gout diagnostic strip covered with gold)
(Figure 2. Scanning delectron microscopic image of paper gout diagnostic strip)
(Figure 3. Scanning electron microscope image of cellulos fiber coated with gold nanoislands)
(Figure 4. Gout diagnosis using tears)
2017.04.27 View 9014 -
KAIST Nanosatellite LINK Launched to the ISS
Courtesy: United Launch Alliance
The KAIST nanosatellite LINK (Little Intelligent Nanosatellite of KAIST) was successfully launched on an Atlas V booster aboard the NASA CRS-7 Mission on April 18 at Space Launch Complex 41, Cape Canaveral Air Force Station in Florida. The KAIST nanosatellite was developed by the research team led by Professor Hyochoong Bang of the Department of Aerospace Engineering.
Aboard the flight to the ISS (International Space Station) were 28 satellites including LINK. They are part of the QB50 Project, an international educational initiative which aims to deploy an array of CubeSat-mounted sensors into Earth’s thermosphere. The project is funded by the European Commission and managed by the von Karman Institute for Fluid Dynamics in Belgium.
The small satellites are hitching a lift into orbit aboard the unmanned resupply spacecraft Cygnus, with a total mass of 83 kilograms. Built to CubeSat specifications, Cygnus will deploy four of the spacecraft following its departure from the space station. LINK will conduct its scientific mission for three months at the station.
The majority of QB50 satellites carry one of three standard instrument packages, consisting of a primary instrument and an array of thermistors, thermocouples, and resistant temperature detectors. LINK is a two-unit CubeSat and weighs two kilograms. It carries an ion-neutral mass spectrometer (INMS), which measures the mass of ions and neutral atoms, as the primary payload of the QB50 project. The secondary payload is two Langmuir probes, which are in-house sensors (m-NLP) developed by Professor Kyong Wook Min’s team of the Department of Physics at KAIST. These are all geared toward collecting long-term continuous in-situ measurements of conditions in Earth’s lower thermosphere.
Professor Bang said, “The QB50 Project is being used for educational purposes. However, the LINK launch will bring a new breakthrough toward collecting information on Earth’s lower thermosphere. Building on these experiences of designing and launching the CubeSat will serve as an opportunity to verify the research results made in our lab firsthand in space.”
(Caption: LINK (Little Intelligent Nanosatellite of KAIST) was launched on an Atlast V booster aboard the NASA CRS-7 Mission on April 18.)
2017.04.25 View 9087 -
Processable High Internal Phase Pickering Emulsion Using Depletion Attraction
Professor Siyoung Choi’s research team from the KAIST Department of Chemical & Biomolecular Engineering used physical force to successfully produce a stable emulsion.
Emulsions, commonly known as cosmetic products, refer to stably dispersed structures of oil droplets in water (or water droplets in oil). Pickering emulsions refer to emulsions stabilized using solid particles, instead of detergent. Traditionally, it is said that water and oil do not mix. Until recently, detergent was added to mix oil and water for dispersion. Emulsions have traditionally been produced using this technique and are currently used for products such as mayonnaise, sun block, and lotion.
On the other hand, Pickering emulsions have been used after stabilization of chemical treatments on solid particle surfaces to enhance adsorption power. However, there were limitations in its application, since the treatment process is complex and its applicable range remains limited. Instead of chemical treatment on Pickering emulsion surfaces, the research team mixed small macromolecules a few nanometer in size with larger solid particles (tens of nanometers to a few micrometers). This induced depletion force was used to successfully stabilize the emulsion.
Depletion force refers to the force a large number of small particles induces to aggregate the bigger particles, in order to secure free space for themselves. In short, the force induces an attraction between larger particles. Until now, depletion force could only be applied to solids and solid particles. However, the research team used macromolecules and large particles such as solid particles and oil droplets to show the applicability of depletion force between solids and liquids. By introducing macromolecules that act as smaller particles, hydrophilic solid particles enhanced the adsorption of solid particles to the oil droplet surface, while preventing dissociation from the particle surface, resulting in the maintenance of a stable state.
The research team confirmed the possibility of the simple production of various porous macromolecular materials using stable Pickering emulsions. Such porous macromolecules are expected to be applicable in separation film, systems engineering, drug delivery, and sensors, given their large surface area.
Professor KyuHan Kim, the first author said, “Until now, depletion force has only been used between solid colloid particles. This research has scientific significance since it is the first example of using depletion force between solid particles and liquid droplets.”
Professor Choi said, “Beyond its academic significance, this technology could contribute to industries and national competitiveness.” He continued, “Since this technology uses physical force, not chemical, to produce stable emulsion, it can be used regardless of the type of solid particle and macromolecule. Further, it could be used in customized porous material production for special purposes.”
The research was published in Nature Communications online on February 1. In particular, this research is significant since an undergraduate student, Subeen Kim, participated in the project as a second author through the KAIST Undergraduate Research Program (URP). This research was funded by the National Research Foundation of Korea.
(Figure 1: Images of the inner structure of porous macromolecules produced using the new technology)
(Figure 2: Images showing the measurement of rheological properties of Pickering emulsions and system processability)
(Figure 3: Images showing a stable Pickering emulsion system)
2017.04.19 View 9201 -
Tactile Sensor for Robot Skin Advanced by KAIST Team
The joint research team of Professors Jung Kim and Inkyu Park from the Department of Mechanical Engineering developed a tactile sensor that can act as skin for robots using silicon and carbon materials. This technology produced a sensor that can absorb shock and distinguish various forms of touch, and it is hoped to be used as robot skin in the future.
Skin serves an important role as the largest organ of the human body. As well as protecting major organs from external shock, skin also measures and distinguishes delicate tactile information and transfer it to the nervous system.
Current robotic sensory technology allows robots to have visual and auditory systems at nearly similar levels to human capacity, but there are limitations in tactile sensors that can detect changes in the environment throughout the body. To apply skin with similar functions as humans to robots, it is essential to develop skin sensor technology with high flexibility and high shock absorption. Another limitation for developing robot skin was connecting numerous sensors all over the body using electric wiring.
To overcome this problem, the research team combined silicon and carbon nanotubes (CNT) to produce a composite, which was then used in combination with a medical imaging technique called electrical impedance tomography (EIT). This led to technology that can distinguish various forms of force over a large area without electrical wiring.
The sensing material can distinguish the location and the size of various forms by touch, and thus can be applied to robot skin that can absorb shock as well as serves as a 3D computer interface and tactile sensor. It can withstand strong force such as a hammer strike, and can be re-used even after partial damage to the sensor by filling and hardening the damaged region with composite. Further, the sensor can be made by filling a 3D shape frame with silicon-nanotube composite. Using this technology, new forms of computer interaces can be developed with both curbed and flat surfaces.
This research was conducted through a collaboration between Professor Park, an expert in nanostructures and sensors, and Professor Kim, an expert in bio-robotics. Hence, the technology is likely to be applied in real products.
Professor Kim said, “Flexible tactile sensors can not only be directly adhered to the body, but they also provides information on modified states in multiple dimensions”. He continued, “This technology will contribute to the soft robot industry in the areas of robot skin and the field of wearable medical appliances.”
Professor Park said, “This technology implemented a next-generation user interface through the integration of functional nano-composite material and computer tomography.”
This research was published in Scientific Reports, a sister journal of Nature, online on January 25. This research was conducted as joint research by first author Hyo-Sang Lee, as well as Donguk Kwon and Ji-seung Cho, and was funded by the Ministry of Science, ICT and Future Planning.
(Fiigrue 1: Robotic hand responding to resistance via a connection with the developed tactile sensor)
(Figure 2: Manufacturing process for pressure-resistant composite using silicon rubber and carbon nanotubes)
(Figure 3: Computer interface using pressure-resistant composite)
2017.04.17 View 12408 -
Nuclease-Resistant Hybrid Nanoflowers
An eco-friendly method to synthesize DNA-copper nanoflowers with high load efficiencies, low cytotoxicity, and strong resistance against nucleases has been developed by Professor Hyun Gyu Park in the Department of Chemical and Biomolecular Engineering and his collaborators.
The research team successfully formed a flower-shaped nanostructure in an eco-friendly condition by using interactions between copper ions and DNA containing amide and amine groups. The resulting nanoflowers exhibit high DNA loading capacities in addition to low cytotoxicity.
Flower-shaped nanocrystals called nanoflowers have gained attention for their distinct features of high surface roughness and high surface area to volume ratios. The nanoflowers have been used in many areas including catalysis, electronics, and analytical chemistry.
Of late, research breakthroughs were made in the generation of hybrid inorganic-organic nanoflowers containing various enzymes as organic components. The hybridization with inorganic materials greatly enhanced enzymatic activity, stability, and durability compared to the corresponding free enzymes.
Generally, the formation of protein nanocrystals requires high heat treatment so it has limitations for achieving the high loading capacities of intact DNA.
The research team addressed the issue, focusing on the fact that nucleic acids with well-defined structures and selective recognition properties also contain amide and amine groups in their nucleobases. They proved that flower-like structures could be formed by using nucleic acids as a synthetic template, which paved the way to synthesize the hybrid nanoflowers containing DNA as an organic component in an eco-friendly condition.
The team also confirmed that this synthetic method can be universally applied to any DNA sequences containing amide and amine groups. They said their approach is quite unique considering that the majority of previous works focused on the utilization of DNA as a linker to assemble the nanomaterials. They said the method has several advantageous features. First, the ‘green’ synthetic procedure doesn’t involve any toxic chemicals, and shows low cytotoxicity and strong resistance against nucleases. Second, the obtained nanoflowers exhibit exceptionally high DNA loading capacities.
Above all, such superior features of hybrid nanoflowers enabled the sensitive detection of various molecules including phenol, hydrogen peroxide, and glucose. DNA-copper nanoflowers showed even higher peroxidase activity than those of protein-copper nanoflowers, which may be due to the larger surface area of the flower- shaped structures, creating a greater chance for applying them in the field of sensing of detection of hydrogen peroxide.
The research team expects that their research will create diverse applications in many areas including biosensors and will be further applied into therapeutic applications.
Professor Park said, “The inorganic component in the hybrid nanoflowers not only exhibits low cytotoxicity, but also protects the encapsulated DNA from being cleaved by endonuclease enzymes. Using this feature, the nanostructure will be applied into developing gene therapeutic carriers.”
This research was co-led by Professor Moon Il Kim at Gachon University and KAIST graduate Ki Soo Park, currently a professor at Konkuk University, is the first author. The research was featured as the front cover article of the Journal of Materials Chemistry B on March 28, Issue 12, published by the Royal Society of Chemistry.
The research was funded by the Mid-Career Researcher Support Program of the National Research Foundation of Korea and the Global Frontier Project of the Ministry of Science, ICT & Future Planning.
(Figure: (A) Schematic illustration of the formation of nuclease-resistant DNA–inorganic nanoflowers. (B) SEM images showing time-dependent growth of DNA-nanoflowers. The concentration of A-rich ssDNA (Table S1, ESI†) was 0.25 mM.)
2017.04.14 View 9364 -
Improving Traffic Safety with a Crowdsourced Traffic Violation Reporting App
KAIST researchers revealed that crowdsourced traffic violation reporting with smartphone-based continuous video capturing can dramatically change the current practice of policing activities on the road and will significantly improve traffic safety.
Professor Uichin Lee of the Department of Industrial and Systems Engineering and the Graduate School of Knowledge Service Engineering at KAIST and his research team designed and evaluated Mobile Roadwatch, a mobile app that helps citizen record traffic violation with their smartphones and report the recorded videos to the police.
This app supports continuous video recording just like onboard vehicle dashboard cameras. Mobile Roadwatch allows drivers to safely capture traffic violations by simply touching a smartphone screen while driving. The captured videos are automatically tagged with contextual information such as location and time. This information will be used as important evidence for the police to ticket the violators. All of the captured videos can be conveniently reviewed, allowing users to decide which events to report to the police.
The team conducted a two-week field study to understand how drivers use Mobile Roadwatch. They found that the drivers tended to capture all traffic risks regardless of the level of their involvement and the seriousness of the traffic risks. However, when it came to actual reporting, they tended to report only serious traffic violations, which could have led to car accidents, such as traffic signal violations and illegal U-turns. After receiving feedback about their reports from the police, drivers typically felt very good about their contributions to traffic safety.
At the same time, some drivers felt pleased to know that the offenders received tickets since they thought these offenders deserved to be ticketed. While participating in the Mobile Roadwatch campaign, drivers reported that they tried to drive as safely as possible and abide by traffic laws. This was because they wanted to be as fair as possible so that they could capture others’ violations without feeling guilty. They were also afraid that other drivers might capture their violations.
Professor Lee said, “Our study participants answered that Mobile Roadwatch served as a very useful tool for reporting traffic violations, and they were highly satisfied with its features. Beyond simple reporting, our tool can be extended to support online communities, which help people actively discuss various local safety issues and work with the police and local authorities to solve these safety issues.”
Korea and India were the early adaptors supporting video-based reporting of traffic violations to the police. In recent years, the number of reports has dramatically increased. For example, Korea’s ‘Looking for a Witness’ (released in April 2015) received more than half million reported violations as of November 2016. In the US, authorities started tapping into smartphone recordings by releasing video-based reporting apps such as ICE Blackbox and Mobile Justice. Professor Lee said that the existing services cannot be used while driving, because none of the existing services support continuous video recording and safe event capturing behind the wheel.
Professor Lee’s team has been incorporating advanced computer vision techniques into Mobile Roadwatch for automatically capturing traffic violations and safety risks, including potholes and obstacles. The researchers will present their results in May at the ACM CHI Conference on Human Factors in Computing Systems (CHI 2017) in Denver, CO, USA. Their research was supported by the KAIST-KUSTAR fund.
(Caption: A driver is trying to capture an event by touching a screen. The Mobile Radwatch supports continuous video recording and safe event captureing behind the wheel.)
2017.04.10 View 10955 -
Crowdsourcing-Based Global Indoor Positioning System
Research team of Professor Dong-Soo Han of the School of Computing Intelligent Service Lab at KAIST developed a system for providing global indoor localization using Wi-Fi signals. The technology uses numerous smartphones to collect fingerprints of location data and label them automatically, significantly reducing the cost of constructing an indoor localization system while maintaining high accuracy.
The method can be used in any building in the world, provided the floor plan is available and there are Wi-Fi fingerprints to collect. To accurately collect and label the location information of the Wi-Fi fingerprints, the research team analyzed indoor space utilization. This led to technology that classified indoor spaces into places used for stationary tasks (resting spaces) and spaces used to reach said places (transient spaces), and utilized separate algorithms to optimally and automatically collect location labelling data.
Years ago, the team implemented a way to automatically label resting space locations from signals collected in various contexts such as homes, shops, and offices via the users’ home or office address information. The latest method allows for the automatic labelling of transient space locations such as hallways, lobbies, and stairs using unsupervised learning, without any additional location information. Testing in KAIST’s N5 building and the 7th floor of N1 building manifested the technology is capable of accuracy up to three or four meters given enough training data. The accuracy level is comparable to technology using manually-labeled location information.
Google, Microsoft, and other multinational corporations collected tens of thousands of floor plans for their indoor localization projects. Indoor radio map construction was also attempted by the firms but proved more difficult. As a result, existing indoor localization services were often plagued by inaccuracies. In Korea, COEX, Lotte World Tower, and other landmarks provide comparatively accurate indoor localization, but most buildings suffer from the lack of radio maps, preventing indoor localization services.
Professor Han said, “This technology allows the easy deployment of highly accurate indoor localization systems in any building in the world. In the near future, most indoor spaces will be able to provide localization services, just like outdoor spaces.” He further added that smartphone-collected Wi-Fi fingerprints have been unutilized and often discarded, but now they should be treated as invaluable resources, which create a new big data field of Wi-Fi fingerprints. This new indoor navigation technology is likely to be valuable to Google, Apple, or other global firms providing indoor positioning services globally. The technology will also be valuable for helping domestic firms provide positioning services.
Professor Han added that “the new global indoor localization system deployment technology will be added to KAILOS, KAIST’s indoor localization system.” KAILOS was released in 2014 as KAIST’s open platform for indoor localization service, allowing anyone in the world to add floor plans to KAILOS, and collect the building’s Wi-Fi fingerprints for a universal indoor localization service. As localization accuracy improves in indoor environments, despite the absence of GPS signals, applications such as location-based SNS, location-based IoT, and location-based O2O are expected to take off, leading to various improvements in convenience and safety. Integrated indoor-outdoor navigation services are also visible on the horizon, fusing vehicular navigation technology with indoor navigation.
Professor Han’s research was published in IEEE Transactions on Mobile Computing (TMC) in November in 2016.
For more, please visit http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7349230http://ieeexplore.ieee.org/document/7805133/
2017.04.06 View 9882 -
Improving Silver Nanowires for FTCEs with Flash Light Interactions
Flexible transparent conducting electrodes (FTCEs) are an essential element of flexible optoelectronics for next-generation wearable displays, augmented reality (AR), and the Internet of Things (IoTs). Silver nanowires (Ag NWs) have received a great deal of attention as future FTCEs due to their great flexibility, material stability, and large-scale productivity. Despite these advantages, Ag NWs have drawbacks such as high wire-to-wire contact resistance and poor adhesion to substrates, resulting in severe power consumption and the delamination of FTCEs.
A research team led by Professor Keon Jae Lee of the Materials Science and Engineering Department at KAIST and Dr. Hong-Jin Park from BSP Inc., has developed high-performance Ag NWs (sheet resistance ~ 5 Ω/sq, transmittance 90 % at λ = 550 nm) with strong adhesion on plastic (interfacial energy of 30.7 J∙m-2) using flash light-material interactions.
The broad ultraviolet (UV) spectrum of a flash light enables the localized heating at the junctions of nanowires (NWs), which results in the fast and complete welding of Ag NWs. Consequently, the Ag NWs demonstrate six times higher conductivity than that of the pristine NWs. In addition, the near-infrared (NIR) of the flash lamp melted the interface between the Ag NWs and a polyethylene terephthalate (PET) substrate, dramatically enhancing the adhesion force of the Ag NWs to the PET by 310 %.
Professor Lee said, “Light interaction with nanomaterials is an important field for future flexible electronics since it can overcome thermal limit of plastics, and we are currently expanding our research into light-inorganic interactions.”
Meanwhile, BSP Inc., a laser manufacturing company and a collaborator of this work, has launched new flash lamp equipment for flexible applications based on the Professor Lee’s research.
The results of this work entitled “Flash-Induced Self-Limited Plasmonic Welding of Ag NW Network for Transparent Flexible Energy Harvester (DOI: 10.1002/adma.201603473)” were published in the February 2, 2017 issue of Advanced Materials as the cover article.
Professor Lee also contributed an invited review in the same journal of the April 3, 2017 online issue, “Laser-Material Interactions for Flexible Applications (DOI:10.1002/adma.201606586),” overviewing the recent advances in light interactions with flexible nanomaterials.
References
[1] Advanced Materials, February 2, 2017, Flash-Induced Self-Limited Plasmonic Welding of Ag NW network for Transparent Flexible Energy Harvester http://onlinelibrary.wiley.com/doi/10.1002/adma.201603473/epdf
[2] Advanced Materials, April 3, 2017, Laser-Material Interactions for Flexible Applications
http://onlinelibrary.wiley.com/doi/10.1002/adma.201606586/abstract
For further inquiries on research:
keonlee@kaist.ac.kr (Keon Jae Lee), hjpark@bsptech.co.kr (Hong-Jin Park)
Picture 1: Artistic Rendtition of Light Interaction with Nanomaterials
(This image shows flash-induced plasmonic interactions with nanowires to improve silver nanowires (Ag NWs).)
Picture 2: Ag NW/PET Film
(This picture shows the Ag NWs on a polyethylene terephthalate (PET) film after the flash-induced plasmonic thermal process.)
2017.04.05 View 10800