• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.253-255
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• 2009

박막태양전지에서 빛을 처음 받아들이는 p-layer는 전체적인 태양전지 특성에 큰 영향을 준다. 본 논문에서는 p-layer의 gas flow rate를 가변하여 증착한 P-I-N cell을 통해 DIV를 측정하고 분석하였다. 더불어 gas flow rate에 따른 p-layer의 특성변화를 토대로 시뮬레이션을 진행하여 실제 소자와 비교하여 보았다. simulation da와 experimental data를 비교해보면 전체적으로 유사한 경향성을 보이며 saturation current는 큰 차이를 보이지 않았으나 ideality factor와 series resistance에서 real device가 비교적 큰 값을 나타내는 것을 볼 수 있었다. 본 연구는 simulation data를 기반으로 real device를 제작하는데 큰 도움이 될 것이다.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.162-167
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• 2004

In this research the Co-simulation technique for an electric power steering system with MATLAB/SIMULINK and a full vehicle model with ADAMS has been developed. The dynamic responses of vehicle chassis and steering system are evaluated. Then, a full vehicle model interacted with EPS control is concurrently simulated with an impulsive steering wheel torque input to analyze the stability of 'free control' or hands free motion for Sports Utility Vehicle. This integrated method allows engineers to reduce the prototype testing cost and to shorten the developing period.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.599-602
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• 2014

본 논문은 FBDtoVerilog 변환기의 correctness 검증을 지원하는 시나리오 생성기에 대해 소개한다. 현재 원자력 발전소의 제어기는 PLC 를 이용하여 개발되고 있지만, 최근 FPGA 를 이용한 제어기 개발의 필요성이 증가하고 있다. 우리는 이를 지원하기 위해 PLC 개발에 사용되는 언어인 FBD를 FPGA 에 사용되는 언어인 Verilog 로 자동 변환하는 변환기 FBDtoVerilog 를 개발 하였다. 하지만 원자력 발전소와 같은 안전 필수 시스템은 철저하고 엄격한 검증 과정이 필수 이기 때문에, 우리는 FBDtoVerilog 를 검증할 수 있는 Co-Simulation 환경을 구축하여 검증할 계획을 가지고 있다. Co-Simulation 환경을 위한 첫 번째 단계로 자동화된 시나리오 생성기를 개발 하였다. 개발된 시나리오 생성기는 도메인 특징을 반영한 시나리오를 생성할 수 있고, 무한한 개수의 시나리오를 자동으로 생성할 수 있는 장점을 가지고 있다.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.3
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• pp.466-477
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• 2015

In this study, a numerical prediction method on manoeuvrability of Wind Turbine Installation Vessel (WTIV) is presented. Planar Motion Mechanism (PMM) captive test for the bare hull of WTIV is carried out in the model basin and compared with the numerical results using RANS simulation based on Open-source Field Operation And Manipulation (OpenFOAM) calculation to validate the developed method. The manoeuvrability of WTIV with skeg and/or without skeg is investigated using the numerical approach along with the captive model test. In the numerical calculations, the dynamic stability index which indicates the course keeping ability is evaluated and compared for three different hull configurations i.e. bare hull and other two hulls with center skeg and twin skeg. This paper proves that the numerical approach using RANS simulation can be readily applied to estimate the manoeuvrability of WTIV at the initial design stage.

• Journal of the Korean Society for Railway
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• v.10 no.3 s.40
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• pp.313-318
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• 2007

In this study, numerical simulations were carried out to analyze the effect of the smoke extraction system and fire shutters in subway station fires using FDS 4.0. Subway station used in the experiment was 145 m long. Simulation results are validated by comparing with experimental results. Simulation results showed good agreement with experimental results within $10^{\circ}C$. 10 MW polystyrene was used as a fuel in the numerical prediction. Numerical predictions were performed in the center-platform type subway station in case of a kiosk fire. Temperature and CO concentration were lowered by the operation of smoke extraction system. But, the operation of fire shutters had little effect on temperature and CO concentration in the platform level.

• Journal of Soil and Groundwater Environment
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• v.19 no.6
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• pp.30-36
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• 2014

The objective of this study is to estimate soil loss in the buffer zone of Guem river with future climate change simulation. Revised Universal Soil Loss Equation (RUSLE) model was used for the estimation of soil loss at the buffer zone of Guem river. As results of simulations, the area of the maximum soil loss potential was estimated as the Cheongsung-myeon Okchun-gun Chungcheongbuk-do. The soil losses were estimated to be 106.67 and 103.00 ton/ha/yr for the 2020 segi (2015-2025) and 2040 segi (2035-2045) in the Cheongsung-myeon area, respectively. Also, the estimated average values of soil losses in the Cheongsung-myeon with future climate change was 110.78 ton/ha/yr.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.817-820
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• 2002

Since a squirrel cage induction motor by NEMA Design types is designed to withstand full-voltage starting, direct starting method can be the most economical one. Starting a squirrel cage motor from standstill by connecting it directly across the line may allow inush currents of approximately 500-600% of rated current at lagging power factor of 35-50%. For many of the large motors, the starting inrush current may be great enough to cause voltage dips, which may adversely affect the building's lighting system. Electric utilities also have restrictions on starting currents, so that voltage fluctuations can be held to prescribed limits. Therefore the need for choosing the most appropriate method of motor starting is quite essential. In this paper, we proposed a plan for the selection of the most appropriate motor starting method, first by way of numeric simulation using manufacturer's data and second by way of actual experience. So far, more often than not, the selection of motor starting method has been accomplished only as regards to the capacity of the motor and the frequency of starting and stopping. But nowadays such high-tech apparatus as soft starters are being developed, and we are on the position to give more attention to clarify the way of selection of the motor starting method.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.309-313
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• 2004

Prediction of green water loads acting an the bow deck is an essential part for the design of bow structures against the green water impact. Proper technique of the green water simulation is highly required for the prediction of green water loads. In this paper, a new numerical method for green water simulation, which is based an predictor-corrector-upwind finite difference scheme of the 2nd kind, is introduced. Through the comparisons between computed' results and experimental measurements, it is verified that the present numerical tool is adequate as a practical calculation tool for the green water problem.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.825-835
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• 2017

This paper aims to build a drone platform based on an optimum design of its single arm. Its single arm is assumed as a cantilevered beam with a tip mass. Based on the numerical optimization theory, validation and optimization of a new design is conducted by comparing the results with the similar ones obtained by ANSYS. Finally, this design is reflected in the control simulation, and the requirement of an optimum structural design considering the resonance situation is satisfied.

• The KSFM Journal of Fluid Machinery
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• v.10 no.2 s.41
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• pp.16-21
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• 2007

Potential advantages of using vapor injection in a two stage rotary compressor for a $CO_2$ heat pump water heater system were addressed in this paper by numerical simulation. Vapor separated from a flash tank in the middle of the expansion process can be used for injection into the second stage suction plenum of the compressor to improve the system performance. Vapor injection increases the intermediate pressure between the two stages, thus increasing the first stage compressor work and reducing that of the second stage. As a whole, however, the compressor input power increases due to injected mass flow rate for the second stage. Computer simulation showed that increment of the cooling capacity by vapor injection exceeded that of the compressor work, thus improving the system performance. COP improvement by vapor injection was calculated to be about 5-14% for normal operating conditions. With vapor injection, a maximum COP was found when the displacement volume of the second stage becomes 90-95% of that of the first stage of the compressor.