• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.65-67
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• 2001

PLC (Power Line Communication) is the communication method using the existing power line installed in houses and offices to convert and transmit high frequency communication signal from tens of KHz to tens of MHz, and receive the filtered signal using high frequency filter. The advantage of PLC is that PLC uses the existing power line installed in houses and offices so it does not require separate power line. Easy and convenient access using electric outlets is another advantage of PLC. However, PLC has some disadvantages such as limited transmission power, high load interference and noise, variable signal attenuation, characteristic of impedance selective possibility of frequency property. This study designed the boiler temperature control system by unit using the modem designed on the basis of technology used for PLC modem, and designed remote control system using internet. After conducting experiments with those two systems, it was possible to control stably. By commercializing this product, we can avoid unnecessary heating of separate temperature control unit, and save the cost according1y, and it is possible to control on a remote site using internet in a more convenient way.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.36-40
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• 2010

In recent society, the electricity is so essential for the human lives. Lots of modern people take many cultural benefits owing to the development of the power systems, the cell phone, the electrical appliances, and etc. However, the problems related to the electromagnetic field generate as the side effects. Examples are the fault in the electric machinery due to the electromagnetic coupling, the fault in the communication devices due to the electromagnetic field around the power line equipments, and the effect upon the human beings due to the electromagnetic field, and etc. In this paper, we induce the vector equation about the magnetic field based on Biot-Savart law. We calculate the magnetic field at the surface of the high speed train with this induced equation and the current in the high speed railroad catenary wire. Finally, we calculate the magnetic field in the high speed train considering the material property like the permeability, the conductivity, and so on.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.211-214
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• 1998

The high power amplifier (HPA) for broadcasting transmitter systems has nonlinear property in terms of input signal power. Hence, it produces AM/AM and AM/PM modulation to the modulated signal. Therefore, the non-linearity results in bandwidth expansion and nonlinear distortion to in-band signal. In this paper, we propose a simple sain-based predistorter that requires less computational burden and less time for the full initialization of the pre-distorter ROM table.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.295-300
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• 2005

In this paper we have designed a two-stage Class I power amplifier operated at 2.4CHz for Class-1 Bluetooth application. The power amplifier employs class-I topology to exploit its soft-switching property for high efficiency. The latch-structured pre-amplifier with amplifiers makes its output signal as sharp as possible for soft switching of the next power amplifier. It improves the overall efficiency of the proposed power amplifier. It shows 65.8$\%$ PAE, 20dB power gain and 20dBm output power.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.24-24
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• 2003

Research activity in the III-V nitrides materials system has increased markedly in the past several years ever since high-brightness blue light-emitting diodes (LEDs) became commercially available. Despite of excellent optical properties of the GaN, however, inherently poor thermal property of the sapphire used as a substrate material n these devices may lead to thermal degradation of devices, especially during their high power operation. Therefore, dependable thermal analysis and packaging schemes of GaN-based LEDs are necessary for solid lighting applications under high power operation. In this paper, emphasis will be placed upon thermal design of GaN-based LEDs. Thermal measurements of LEDs on chip and packaging scale were performed using the liquid crystal thermographic technology and micro thermocouples for different bias conditions. By a series of optical arrangement, hot spots with specific transition temperatures were obtained with increasing input power. Thermal design of LEDS was made using the finite element method and analytical unit temperature profile approach with optimal boundary conditions. The experimental results were compared to the simulated data and the results agree well enough for the establishment of dependable prediction of thermal behavior in these devices. The paper will present a more detailed understanding of the thermal analysis of the GaN-based blue and white LEDs for high power applications.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.3
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• pp.95-99
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• 2008

This paper proposes a new minimal resource high-level synthesis algorithm for low power design automation. The proposed algorithm executes an efficient approach to minimize the power consumption of the functional units in a circuit during the high level synthesis. In this paper, we visit all control steps one by one to reduce the switching activity in CDFG. The register sharing algorithm determines the minimum register after the life time analysis of all variable. According to property of input signal for functional unit, the proposed method visits all control step one by one and determines the resource allocation with minimal power consumption at each control step in a greedy fashion. The effect of the proposed algorithm has been proved through various filter benchmark to adopt a new scheduling and allocation algorithm considering the low rover.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.409-416
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• 2005

For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.25-31
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• 2018

A boiler system transforms water to pressured supercritical steam which drives the running of the turbine to rotate in the generator to produce electricity in power plants. Materials for building the tube system face challenges from high temperature creep damage, thermal fatigue/expansion, fireside and steam corrosion, etc. A database on the creep resistance strength and steam oxidation of the materials is important to the long-term reliable operation of the boiler system. Generally, the ferritic steels, i.e., grade 1, grade 2, grade 9, and X20, are extensively used as the superheater (SH) and reheater (RH) in supercritical (SC) and ultra supercritcal (USC) power plants. Currently, advanced austenitic steel, such as TP347H (FG), Super304H and HR3C, are beginning to replace the traditional ferritic steels as they allow an increase in steam temperature to meet the demands for increased plant efficiency. The purpose of this paper is to provide the state-of-the-art knowledge on boiler tube materials, including the strengthening, metallurgy, property/microstructural degradation, oxidation, and oxidation property improvement and then describe the modern microstructural characterization methods to assess and control the properties of these alloys. The paper covers the limited experience and experiment results with the alloys and presents important information on microstructural strengthening, degradation, and oxidation mechanisms.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.151-151
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• 2012

A new plasma process, i.e., the combination of PIII&D and HIPIMS, was developed to implant non-gaseous ions into materials surface. HIPIMS is a special mode of operation of pulsed-DC magnetron sputtering, in which high pulsed DC power exceeding ~1 kW/$cm^2$ of its peak power density is applied to the magnetron sputtering target while the average power density remains manageable to the cooling capacity of the equipment by using a very small duty ratio of operation. Due to the high peak power density applied to the sputtering target, a large fraction of sputtered atoms is ionized. If the negative high voltage pulse applied to the sample stage in PIII&D system is synchronized with the pulsed plasma of sputtered target material by HIPIMS operation, the implantation of non-gaseous ions can be successfully accomplished. The new process has great advantage that thin film deposition and non-gaseous ion implantation along with in-situ film modification can be achieved in a single plasma chamber. Even broader application areas of PIII&D technology are believed to be envisaged by this newly developed process. In one application of non-gaseous plasma immersion ion implantation, Ge ions were implanted into SiO2 thin film at 60 keV to form Ge quantum dots embedded in SiO2 dielectric material. The crystalline Ge quantum dots were shown to be 5~10 nm in size and well dispersed in SiO2 matrix. In another application, Ag ions were implanted into SS-304 substrate to endow the anti-microbial property of the surface. Yet another bio-application was Mg ion implantation into Ti to improve its osteointegration property for bone implants. Catalyst is another promising application field of nongaseous plasma immersion ion implantation because ion implantation results in atomically dispersed catalytic agents with high surface to volume ratio. Pt ions were implanted into the surface of Al2O3 catalytic supporter and its H2 generation property was measured for DME reforming catalyst. In this talk, a newly developed, non-gaseous plasma immersion ion implantation technique and its applications would be shown and discussed.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.1-8
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• 2003

In this study, the high performance BCD device structure which satisfies the high voltage and fast switching speed characteristics is devised. Through the process and device simulation, optimal process spec. & device spec. are designed. We adapt double buried layer structure, trench isolation process, n-/p-drift region formation and shallow junction technology to optimize an electrical property as mentioned above. This I.C consists of 20V level high voltage bipolar npn/pnp device, 60V level LDMOS device, a few Ampere level VDMOS, 20V level CMOS device and 5V level logic CMOS.