• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.2
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• pp.49-56
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• 2001

Diamond thin films have been deposited on the silicon substrate by inductively coupled radio frequency plasma enhanced chemical vapor deposition system. The morphological features of thin films depending on methane concentration and deposition time have been studied by scanning electron microscopy and Raman spectroscopy. The diamond particles deposited uniformly on silicon substrate($10{\times}10[mm^2]$) at the pressure of 1[torr], a methane concentration of 1[%], a hydrogen flow rate of 60[sccm], a substrate temperature of $840\{sim}870[^{\circ}C]$, an input power of 1[kw], and a deposition time of 1[hour]. With increasing deposition time, the diamond particles grew, and than about 3 hours have passed, the graphitic phase carbon thin film with "cauliflower-like" morphology deposited on the diamond thin films.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.10
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• pp.501-507
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• 2001

In this paper, new high-efficiency zero voltage switching (ZVS) AC-DC boost converter is proposed to achieve power factor correction by simplifing energy recovery circuit. A lot of high power factor correction circuits have been proposed and applied to increase input power factor and efficiency. Most of these circuits may obtain unity power factor and achieve sinusoidal current waveform with zero voltage or/and zero current switching. However, it is difficult for them to obtain low cost, small size, low weight, and low noise. The topology proposed to improve these problems can compact the devices in circuit and can achieve high efficiency ZVS AC-DC boost converter. Simulation and experimental results show that this topology is capable of obtaining high power factor and increasing the efficiency of the system.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.44-45
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• 2014

본 논문은 ITER의 플라즈마 제어를 위하여 자기적으로 결합된 초전도 PF 코일에 흐르는 전류를 제어하는 기법과 RTDS 실험결과를 분석하였다. MATLAB/SIMULINK를 이용하여 유도 결합된 4개의 초전도코일을 모델링하여 전류제어기법을 시뮬레이션하였으며, 실험은 RTDS를 이용하여 진행하였다. 각 부하전류가 전류 지령치를 추종할 때, 동시다발적으로 발생하는 상호 인덕턴스와 전류 극성변화의 영향을 MIMO(Multi Input Multi Output) 시스템 기반으로 하여 각 초전도코일의 전압변화 특성을 해석하였다. 시뮬레이션과 실험을 통해 MIMO 시스템 특성의 유도 결합된 초전도코일의 전류제어 특성을 검증하였다.

• Water Engineering Research
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• v.5 no.2
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• pp.81-99
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• 2004

Long term streamflow regime under virtual climate change scenario was examined. Rainfall forecast simulation of the Canadian Global Coupled Model (CGCM2) of the Canadian Climate Center for modeling and analysis for the IPCC SRES B2 scenario was used for analysis. The B2 scenario envisions slower population growth (10.4 billion by 2010) with a more rapidly evolving economy and more emphasis on environmental protection. The relatively large scale of GCM hinders the accurate computation of the important streamflow characteristics such as the peak flow rate and lag time, etc. The GCM rainfall with more than 100km scale was downscaled to 2km-scale using the space-time stochastic random cascade model. The HEC-HMS was used for distributed hydrologic model which can take the grid rainfall as input data. The result illustrates that the annual variation of the total runoff and the peak flow can be much greater than rainfall variation, which means actual impact of rainfall variation for the available water resources can be much greater than the extent of the rainfall variation.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.2
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• pp.29-35
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• 1993

A guided-wave TE to TM mode converter was demonstrated by using of the off-diagonal electrooptic coefficients in LiTaO$_{3}$. The input mode is coupled to the other orthogonal mode by the electrooptically induced off-diagonal polarizability. Compared with LiNbO$_{3}$, LiTaO$_{3}$ provides a smaller birefringence and thus a larger phase match period and larger optical bnadwidth. A novel electrode structure allowed a first-order Bragg-coupling phase matching. TE/TM mode conversion efficiency of 90% at 25 [V] was demonstrated with ${\lambda}$=0.63$\mu$m He-Ne laser.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1327-1330
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• 2008

A novel fiber optic solution is provided to efficiently mix visible colors. Full color synthesis was achieved utilizing a novel $3{\times}1$ hard polymer clad fiber (HPCF) coupler along with red, green and blue (RGB) light emitting diode (LED) primaries. Varying the intensities of RGB LEDs that are coupled to three input ports, the device rendered a full color with an ultra wide CIE color gamut. Potential applications in pica-projection displays and LED backlights will be discussed.

• Journal of Information Display
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• v.9 no.2
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• pp.9-13
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• 2008

A novel push-pull voltage converter structure, using a switched capacitor type voltage doubler, is proposed. The circuit is constructed with a two-stage push-pull voltage doubler that has a stable operation with small output ripple. The two-stage voltage doubler creates the output voltage 4Vdd. The high clock signal is cross-coupled to the input of the second stage with the opposite phase to reduce two switching transistors and capacitors. Simulation results verify that even with a reduced number of transistor and capacitor, there is no circuit performance loss. Adding one capacitor and two switching transistors the circuit can be changed to eight times of Vdd maker.

• Journal of Information Display
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• v.6 no.1
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• pp.12-16
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• 2005

Gate and data drivers are essential for driving active matrix display. In this study, we integrate drivers with a-Si:H to develop a compact, better reliability and cost effective display. We design and fabricate drivers with conventional a-Si:H thin film transistors (TFTs). The output voltages are investigated according to the input voltage, temperature and operation time. Based on these studies, we propose here a new driver to prevent gate line from the floated state. For the external coupled voltage fluctuation, the proposed driver shows better stability.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.1-6
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• 2002

The integration of Geographic Information Systems (GIS) with the hydrodynamic model was conducted in order to revitalize the use of geographical information and to aid in the understanding of tidal circulation patterns. A 2D finite difference numerical model was used to simulate n tidal circulation in the Suyoung Bay in Busan, Korea. CIS, especially the ArcView S/W is used to input the data of the numerical model, and is also used for the visualization of model outputs on the ground in the loosely coupled method. In this paper, an electronic navigational chart (ENC), which provides more accurate information in the ocean and coastal areas than any other digital information, is used as a base map for this integration. With the help of GIS, the integration can support th understanding of oceanographic information.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.350-353
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• 2000

In this paper, we designed the microstrip patch antenna with L-shaped aperture, which greatly enhances its bandwidth. We optimized to get a maximum bandwidth. The microstrip patch antenna with L-shaped aperture has the widest bandwidth of the conventional aperture coupled microstrip patch antenna. This antenna also has the low-cross polarization level. The effects of changing several key design parameters of the antenna are investigated. We calculated the VSWR, input impedance, and radiation pattern.