• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.7
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• pp.454-458
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• 2017

$Bi_2Te_3$-based alloys have been intensively investigated as active materials for thermoelectric power generation devices from low-temperature (< $250^{\circ}C$) waste heat. In the present study, we fabricated Pb-doped, p-type $Bi_{0.48}Sb_{1.52}Te_3$ polycrystalline bulks by using meltsolidification and spark plasma sintering techniques, and evaluated their thermoelectric transport properties in an effort to develop optimized composition for low-temperature power generation applications. The electronic and thermal transport properties of $Bi_{0.48}Sb_{1.52}Te_3$ could be manipulated by Pb doping. As a result, the temperature for a peak thermoelectric performance (zT) gradually shifted toward higher temperatures with Pb content, suggesting that thermoelectric power generation efficiency can be enhanced by controlled Pb doping.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.1
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• pp.83-88
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• 2002

To increase the device linearities and the breakdown-voltages of FETs, $Al_{0.25}$G $a_{0.75}$As/I $n_{0.25}$G $a_{0.75}$As/A $l_{0.25}$G $a_{0.75}$As partially doped channel FET(DCFET) structures are proposed. The metal insulator-semiconductor(MIS) like structures show the high gate-drain breakdown voltage(-20V) and high linearities. We propose a partially doped channel structure to enhance the device linearity to the homogeneously doped channel structure. The physics of partially doped channel structure is investigated with 2D device simulation. The devices showed the small ripple of the current cut-off frequency and the power cut-off frequency over the wide bias range. bias range.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.9-18
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• 2005

Flicker is the 'variation in brightness or he perceived won stimulation by intermittent or temporally non uniform light'. This phenomenon is blown as the cause of eye strain and headaches. Many researchers are dedicated to reducing this phenomenon. The flicker phenomenon also exists in PDP as some other display types, and is a critical problem in 50 Hz PDP. However, it is difficult to define flicker by more than one subjective judgment. So, an objective measurement of flicker is necessary and convenient for research on displays. In this paper, a computational prediction model is proposed which is used to predict luminance flicker (not chromatic flicker) by giving a quantitative output that describes the probability of occurrence of flicker. Through this work, we expected to provide a practical tool for flicker-free design in PDP.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.3
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• pp.51-58
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• 2008

This paper is a study of a prevention of power folding controller's thermal degradation. Power folding technology has been applied for many fields such as side rear vision mirror of vehicles, windshield wiper, antenna, power window. These controllers have been comprised with traditional DC moors, Switching electronic devices, and relays. But this methods have a limitation to overcome such problems of product reliability, endurance, noise margins. Therefore on this paper, to detect the movement of motor, sensing motor brush noise on a load sensing part has been used and controlling a precise RC timing control minimizes the thermal deterioration of motor. And using MOS FETs as a electronic switching device increases life-time and liability of control circuit. After testing such circuit and control method, repetition of operating time, cut-off time, wide operation voltage, power noise margin ware increased over eleven-fold.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1135-1140
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• 2016

The main challenge in designing wearable WBANs is to guarantee the balance of QoS demands in the network with the low power constraints of limited battery powered nodes. Low power devices implanted in or attached to the body should be designed to meet minimum energy requirements due to their limited battery life and be small in size to be easily wearable. In this paper, we propose a method for optimizing channel allocation method that is compatible with the IEEE 802.15.6 standard, enables the maximum amount of power charge at idle, guarantees the QoS of a WBAN, and provides the reliable date transmission between nodes and hubs in the network. Our extensive simulations will show that the method we propose not only maximizes the QoS in packet transmission but also improves the level of energy efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1494-1502
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• 2016

With the increasing availability of medical sensors and Internet of Things(IoT) devices for personal use, considering the interaction with users, it is planned to add intelligent function design to the fashionable jewelry, and develop composite multi-function intelligent jewelry through sensors identification. By means of IoT technology, while possessing communication function of intelligent jewelry, the function of intelligent jewelry can be expanded to the linkage network. In order to rapidly manage the mass data produced by intelligent jewelry sensors based on IoT, an intelligent jewelry system for health management is designed and an ontology model of intelligent jewelry system based on IoT is worked out. After the state of the services through the smart phone application is shown. The application provides a personalized service to the user and to determine the risk to show the guide lines according to the disease.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1825-1830
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• 2015

In some cases, despite the pedestrian jaywalking pedestrian traffic lights to red, or even wait for the walk signal to stand down in the driveway. If this is the case may be liable to lead to a traffic accident. Thus, using an infrared sensor wateuna adopted the approach that the warning announcement when a pedestrian enters the driveway, curved pedestrian crossing the intersection in this case, it is difficult to install. In this paper, we propose a Fitness referral system utilizes a built-in sensor of the Android mobile devices. For this purpose, the sensor is a proximity sensor using an acceleration sensor. The proximity sensor has a number of disadvantages compared to the high precision battery power, the acceleration sensor accuracy, fast response time, on the other hand, the disadvantage is the lower. Close to reduce battery consumption of the sensor, BMI of the user sensor control mechanism and increase the accuracy of the acceleration sensor (Body Mass Index) obtained after the index was applied to the recommendation algorithm, which like the movement mechanism.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.425.1-425.1
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• 2014

Thermal transport in nanomaterials is not only scientifically interesting but also technological important for various future electronic, bio, and energy device applications. Among the various computation approaches to investigate lattice thermal transport phenomena in nanoscale, the atomistic nonequilibrium Green's function approach based on first-principles density functional theory calculations appeared as a promising method given the continued miniaturization of devices and the difficulty of developing classical force constants for novel nanoscale interfaces. Among the nanometerials, carbon atomic chains, namely the cumulene (all-doulble bonds, ${\cdots}C=C=C=C{\cdots}$) and polyyne (alternation of single and triple bonds, ${\cdots}C{\equiv}C-C{\equiv}C{\cdots}$) can be considered as the extream cases of interconnction materials for nanodevices. After the discovery and realization of carbon atomic chains, their electronic transport properties have been widely studied. For the thermal transport properties, however, there have been few literatures for this simple linear chain system. In this work, we first report on the development of a non-equilibrium Green's function theory-based computational tool for atomistic thermal transport calculations of nanojunctions. Using the developed tool, we investigated phonon dispersion and transmission properties of polyethylene (${\cdots}CH2-CH2-CH2-CH2{\cdots}$) and polyene (${\cdots}CH-CH-CH-CH{\cdots}$) structures as well as the cumulene and polyyne. The resulting phonon dispersion from polyethylene and polyene showed agreement with previous results. Compared to the cumulene, the gap was found near the ${\Gamma}$ point of the phonon dispersion of polyyne as the prediction of Peierls distortion, and this feature was reflected in the phonon transmission of polyyne. We also investigated the range of interatomic force interactions with increase in the size of the simulation system to check the convergence criteria. Compared to polyethylene and polyene, polyyne and cumulene showed spatially long-ranged force interactions. This is reflected on the differences in phonon transport caused by the delicate differences in electronic structure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1981-1989
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• 2017

In accordance with the global strengthening of security systems for the safety of the shipping and logistics industry, the development of core technologies within the field has become a key in the establishment of Korea's own national logistics security system. Further in line with these global developments, there is growing attention within Korea to the development of portable radiation detectors capable of detecting gamma ray nuclides. In addition, many parts are becoming localized. In this research, instead of Pulse Shaping Board, which is used in existing portable radiation detectors, we have implemented an Algorithm to discriminate nuclides and correct the temperature conversion efficiency of the scintillator. This paper aims to improve the performance of these devices through the implementation of a temperature conversional algorithm within the scintillator of the A9-based digital portable radiation detector.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1935-1941
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• 2013

We can use NAT(Network Address Translation) technology to solve the lack of IP address. The problem of NAT traversal is happened when the filtering characteristics of NAT remove the packet that has no binding in the address translation table of NAT. There were many kinds of way to solve these problems by using additional device. Lately, network market is changed into integrating wired and wireless network by the IMS(IP Multimedia Subsystem). The IMS integrates to control network of wired and wireless network, has emerged to control convergence network effectively. Lately, the additional devices like IBCF(Interconnection Border Control Function) and IBGF(Interconnection Border Gateway Function) are used to solve the NAT traversal problem in the IMS. In this paper, we propose the solution of NAT traversal using P-CSCF without any additional equipment in the IMS.