Korean
Supercritical CO₂-cooled micro..
In the near future, micro-modular nuclear reactors will be developed and will supply electricity needs in various regions. Micro-modular reactors have better safety and are easier to maintain compared to conventional large reactors, leading to a lower probability of severe accidents. Even in case of an accident, the total amount of radioactive material is low. Therefore, damage to the environment can be minimized. After a permanent shutdown, the reactor module can be taken back to the factory and decommissioned, leaving a minimum amount of radioactivity at the reactor site. Conventional reactors use the water cycle, but the newly proposed micro-modular reactor of KAIST utilizes supercritical CO2 for cooling and power generation. This allows long life spans up to 20 years without refueling. Moreover, the power generation system can be reduced in size such that the entire module can be transported by truck.
Development of a sustainable ..
AnAn artificial cardiac pacemaker is an implantable medical device used to normalize an abnormal heart rate by stimulating the cardiac nerves. However, repetitive surgeries are required for the timely replacement of pacemakers due to the limited lifespan of their batteries. This problem can be resolved by directly recharging the battery inside the human body or with self-powered heart stimulations, and thus minimizing the medical and economic burdens on patients. This work experimentally describes how flexible single-crystal PMN-PT thin film on a thin plastic substrate can be utilized as a high-performance self-powered energy harvester by slight bending motions for an artificial cardiac pacemaker. The energy harvesting device generates one of the highest short-circuit currents of 0.22 mA and an open-circuit voltage of 8.2 V, which can sufficiently meet the high standards for cardiac nerve stimulation. This flexible PMN-PT thin-film nanogenerator was applied not only to charge batteries and turn on 120 LEDs, but also to render artificial pace-making without an external power source. This result can be utilized to relieve the economic and medical burdens of patients by increasing the replacement cycle of the batteries of cardiac pacemakers. Furthermore, for clinical purposes, the current achievement will improve the development of self-powered cardiac pacemakers as well as prevent heart attacks via the additional real-time diagnoses of heart arrhythmia.
Development of a Dual-Fuel Cel..
This technique selectively removes NOx from exhaust gas in a fuel cell system that utilizes Fe(II)EDTA (ferrous-EDTA) to adsorb and capture NOx, while using the electrochemical-oxidation-reduction potential differences between ferrous-EDTA and ferric-EDTA (Fe(III)EDTA) to produce electricity from the fuel cell system. With its principle based on a fuel cell, the NOx capture technique has marked advantages over conventional SCR processes in that the technique is 1) operational at room temperature, 2) requires less of a noble metal catalyst, 3) generates additional electricity, and 4) has the potential to produce nitric acid with the captured NOx. A lab-scale experiment proved the process is efficient with a removal rate exceeding 99%, making it capable of processing 1 ton of NOx per year. Because pure NOx is captured through the system, the components for nitric acid as well as nitric fertilizer are provided. In addition, the research team is now working extensively methods to utilize the captured NOx, such as registering a patent for the production of a high-value-added product in a bioethanol-integrated production system.
OncoSearch: A web tool that se..
The automatic identification of gene-cancer relationships from a very large volume of biomedical text is an important task for cancer research. OncoSearch is a web tool which was developed to allow the user to query the biomedical literature for rich textual information on cancer-related genes and to show the results for further insight into oncogenesis. OncoSearch can classify genes into oncogenes, tumor-suppressor genes, or biomarkers by taking into full account of both the implicit and explicit information on their roles. The tool characterizes gene-cancer relationships with 1) how a gene changes, 2) how a type of cancer changes, and 3) the causality between the gene and the cancer, and infers the respective roles of genes in relation to cancers.
Development of Wearable Thermo..
The era of the IoT (Internet of Things) is expected to start in the near future. For the IoT era, people will be able to carry many sensors attached to their body, communicating with the surrounding environment. The frequent charging of the batteries to operate these sensors will be quite burdensome, however. Therefore, with the development of a self-powered system using energy harvesting technology, the IoT will be easily adopted in many systems. A self-powered sensor system for the IoT requires the integration of energy harvesting technology into sensor networks. If body heat can be used to generate electricity, it will be an ideal solution, as it can make wearable sensors operable anytime and anywhere. In order to convert heat energy to electricity, a thermoelectric generator (TEG) can be used. However, conventional TEGs are heavy, bulky, and rigid and are therefore not easy to attach onto the human body. Therefore, a TEG in wearable form must be developed. In this research, a wearable TEG is realized using a screen printing technique and with glass fabric. It is demonstrated that the wearable TEG can generate enough power to operate wearable sensors. The wearable TEG does not have a rigid substrate which causes thermal energy loss, giving it the benefit of being able to utilize the thermal energy from the human body fully. The wearable TEG is very light (0.13 g/cm2), and fully flexible. It can be used to power wearable sensors. It can also be used for medical patches and other wearable systems as well as in industrial applications such as automobiles, power plants, and airplanes.
Core component technologies ..
Since video data has a nature of large data sizes, it is often necessary to compress them for efficient storage and transmission. Moreover, for the interoperability among digital devices, MPEG-2 Video and H.264/AVC(Advanced Video Coding) standards have often been used for digital TV/broadcasting and DMB/IPTV services. Until the H.264/AVC standard, video data has been encoded in 16×16 pixel units for every input frame, which limits the coding efficiency. In this research, a flexible extended coding block structure has been designed to enhance the coding efficiency, which makes it easier the adaptation to various image signal characteristics. The previous video coding standards only allow each macroblock (MB) to be either intra-coded or inter-coded. In our coding block structure, each coding unit block which is larger than the MB size can flexibly partitioned into many sub-blocks, each of which can be coded in either intra or inter coding modes. That is, each coding unit block is allowed to have both inter-coded and intra-coded sub-blocks, and to use variable block-sized transforms, which can significantly improve the overall coding efficiency. This coding unit block structure of High Efficiency Video Coding, which has been jointly standardized by ITU-T and ISO/IEC, has almost the similar block structure as our design. HEVC is expected to be popularly used for UHD TV and ultra high quality video coding. Our method and design for flexible coding unit structure and coding methods has been registered as patents which have been evaluated as essential patents of HEVC. So, KAIST became, as an essential HEVC patent holder, an Original Licensor of the HEVC patents program managed by MPEG-LA. Therefore, KAIST has an opportunity of benefiting from significant amounts of licensing fees for HEVC standard patents.
Facile synthetic method for pr..
We successfully synthesized highly homogeneous graphene quantum dots (GQDs) and graphene oxide quantum dots (GOQDs) by means of the chemical exfoliation of graphite nanoparticles. GQDs and GOQDs were produced at high yields as single-layered and circular shapes within a diameter 4 nm. While various oxygenous functional groups were rich on the surfaces of the GOQDs, the GQDs showed a pure sp2 carbon crystalline structure without oxygenous defects, thereby providing an ideal platform for in-depth study of the photoluminescence origin of nano-sized graphene. We also showed clear blue- and green-color emissions from GQDs and GOQDs, respectively. By characterizing the optical properties of GQDs and GOQDs, we have revealed that the green luminescence of GOQDs originates from defect states with oxygenous functional groups, whereas the blue luminescence of GQDs is mainly caused by intrinsic states in the high-crystalline structure. In contrast to previously reported GQD fabrication methods, our approach produces stable luminescent pristine GQDs and GOQDs at a high yield and with good reproducibility, which are essential requirements for both biological and electronic applications using nano-sized graphene.
Nanofiber-graphene composite..
Lithium-air (Li-air) batteries, which utilize oxygen as a cathode electrode instead of heavy Li-transition metal oxides, have attracted much attention as one of the most attractive candidates to replace conventional Li-ion batteries. Li-Air batteries are however associated with significant capacity fading (poor cycling performance) due to the irreversible reaction characteristics of the Li2O2 product. We successfully proposed a cost-effective electrospinning route for the facile synthesis of a highly efficient catalyst composed of metal-oxide nanofibers functionalized on nonoxidized graphene nanoflakes with a high surface area and high conductivity. Cobalt oxide nanofiber-graphene composite catalysts are essential in the development of long-cycling Li-oxygen batteries, which can be used as an energy source for the operation of an electric vehicle.
Microbial production of gaso..
For the first time in history, a research team led by Prof. Sang Yup Lee of the Chemical & Biomolecular Engineering Department developed a bacterial strain to produce short-chain alkanes - otherwise known as gasoline - from renewable resources such as glucose through metabolic engineering. By engineering the fatty acid metabolic pathway in E. coli, fatty acid derivatives shorter than normal intracellular fatty acids metabolites were produced. These shorter fatty acid derivatives form an essential part of gasoline. A novel synthetic pathway was also designed and consequently introduced for the biosynthesis of short-chain alkanes. With these novel strategies, gasoline production of 580 mg per liter of culture was achieved from the final E. coli strain. Considering that this platform, E. coli, is also capable of producing fuels and chemicals from renewable resources, the transition from the conventional petro-chemical industry to a bio-chemical industry is now much closer to becoming a reality. This study was selected as the Journal Cover Paper in Nature and was chosen as a Faculty of 1000 Prime (F1000Prime) entry.
Mining tera-scale graphs
Graph mining aims to find patterns and anomalies in graphs which are used to model various objects, including computer networks, social networks, and protein-protein interaction networks. We propose a tera-scale graph mining system and algorithms in relation to eigensolver, tensor, and graph visualization/summarization/anomaly detection to handle graphs with more than hundreds of billions of nodes spanning hundreds of terabytes. The proposed system will analyze tera-scale graphs, which could not be handled before, leading to various applications including recommendation, cyber security, fraud detection, and spammer detection systems.
Low-power next-generation 100G..
A research team at the KAIST developed an extremely low-powered IC for Ethernet that consumes less electricity than 1W but is able to send and receive data at a high speed of 100 gigabits per second (Gbps). Each day, billions of people surf the Internet for information, entertainment, and education. The amount of energy consumed by data centers doubled from 2000 to 2006, reaching more than 60 billion kilowatt hours per year. For example, the energy consumption of data centers in the US will reach 8% of the country's total electric power consumption by 2020. The ultra-low power circuit, 100-gigabit full-transceiver CDR developed here is the world's first solution that can be loaded onto the smallest communication module (CFP4/QSFP28), the next-generation chip for data centers. Compared to other chip producers, the 100 Gbps CDR is a greener version of technology that improves the energy efficiency of data centers while maintaining high data transmission speeds.
A high DOF anthropomorphic r..
? For several decades, robot hands have been studied for medical and industrial purposes. Due to the limitations of actuators and actuation mechanisms, it has remained difficult to design robot hands such that they are compact and can achieve multiple degrees of freedom. In this study, we newly proposed the concept of ‘dual-mode twisting actuation’ to overcome the limitations on the performance of existing robot hands. ‘Dual-mode twisting actuation’ refers to a type of transmission mechanism that generates powerful movement through the twisting of two wires. It has several advantages, such as good flexibility, a light weight, a compact size and a large stroke (46%). The weight of the robot hand designed with the proposed mechanism is identical to that of the human hand, and it can generate a large amount of force (50N max) and fast movements (4Hz). The designed robot hand is expected to be widely used in various applications with control through bio-signals.