• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.6
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• pp.813-820
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• 2003

The purpose of this research is to develop the model of turbulence modulation due to the presence of particles in various types of particle-laden flows Available experimental data are surveyed and the dependence of turbulence modulation of carrier-phase on particle size, concentration and. particle Reynolds number are examined. This study takes into account the effect of wake produced by particle, the drag between phases and the velocity gradient in the wake to estimate the production of turbulence. The model of turbulence modulation using the mixing length theory under the assumption of equilibrium flow is proposed. Numerical results show that the model is successful in predicting the characteristics of the particle-laden in various flow conditions both qualitatively and quantitatively.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.55-59
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• 2003

In this paper, we estimate the performance requirements of general-purpose DSP for Carrier Recovery of OFDM DVB-T receiver. Firstly, we transported the designed fixed-point OFDM DVB-T model to a floating-point software model written in C. Then, we measured the number of instruction cycles required for operation of Carrier Recovery in time. We use SignalMaster$\^$TM/ DSP platform of LYRtech Inc. as a environment of estimation, and Simulink$\^$TM/ as a graphical interface, Code Composer StudioTM of TI as profiler and compiler, and SPW$\^$TM/ for presenting functional reliability and comparing the performance distortion with fixed-point model. As a result, we show the required number of DSPs in our DSP-based system, and introduce the need of Multi-DSP-based system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.29-32
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• 2000

In this paper, an analytical model for I-V characteristics of a HEMTs is Proposed. The developed model takes into account the temperature dependence of drain current. In high-speed ICs for optical communication systems and mobile communication systems, temperature variation affects performance; for example the gain, efficiency in analog circuits and the delay time, power consumption and noise mrgin in digital circuits. To design such a circuit taking into account the temperature dependence of the current-voltage characteristic is indispensible. This model based on the analytical relation between surface carrier density and Fermi potential including temperature dependent coefficients.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.120-124
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• 2000

In this paper, the effects of trap distribution on switching characteristis of a lateral insulated gate bipolar transistor (LIGBT) are investigated. The simulations are performed in order to to analyze the effect of the positon, width and concentration of trap distribution model with a reduced minority carrier lifetime using 2D device simulator MEDICI. The turn off time for the proposed LIGBT model A with the trap injection is 0.8$mutextrm{s}$. These results indicate the improvement of about 2 times compared with the conventional LIGBT. It is shown that the trap distribution model is very effective to reduce the turn-off time with a little increasing of on-state voltage drop.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.41-45
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• 2015

In this study reviewed the validity of the estimated optimum trim by the numerical analysis. For this purpose, the numerical analysis of the trim optimization for 6500TEU container carrier and capesize bulk carrier were carried out using Star-CCM+, which results were compared with the results of model tests. The reliability of results of the numerical analysis was confirmed via comparing the resistance determined by the numerical analysis and model test. The performance of self-propulsion at each trim conditions were estimated using the calculated resistance by numerical analysis. The BHP at each trim condition were calculated by estimated performance of self-propulsion, which trend of results were confirmed similar trend of result of model test.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.3
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• pp.189-198
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• 2006

A new analytical model has been proposed for predicting the sheet carrier density of Metal insulator Semiconductor High Electron Mobility Transistor (MISHEMT). The model takes into account the non-linear relationship between sheet carrier density and quasi Fermi energy level to consider the quantum effects and to validate it from subthreshold region to high conduction region. Then model has been formulated in such a way that it is applicable to MESFET/HEMT/MISFET with few adjustable parameters. The model can also be used to evaluate the characteristics for different gate insulator geometries like T-gate etc. The model has been extended to forecast the drain current, conductance and high frequency performance. The results so obtained from the analysis show excellent agreement with previous models and simulated results that proves the validity of our model.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.1
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• pp.15-22
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• 2011

In this paper, cavitation patterns of model tests were compared with those of full-scale measurement for a propeller of crude oil carrier which was suffered from erosions on suction side of blade tip region. Cavitation tests were performed at design and ballast draft using model and full scale nominal wakes. A model ship and wire mesh method was used for the simulation of wake patterns of model nominal wakes. For the prediction of full-scale wake patterns, a RANS solver(Fluent 6.3) was used and wire mesh method was used for the simulation of the full scale wakes. Comparison results show that cavitation patterns using predicted full-scale wake patterns are closer to cavitation patterns of full-scale measurement at ballast draft condition. Also, cloud cavitations were observed on the position of eroded area at both full-scale measurement and cavitation tests using simulated full-scale wake patterns.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1956-1958
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• 1999

The analysis of hole injection efficiency at the p+/n-drift layer junction in non-punchthrough IGBT structure is presented. This analysis takes into account carrier concentration variations by conductivity modulation. Good agreement between this analysis and simulation is found over a wide range of carrier lifetime and current density. The proposed analytical model of the hole injection efficiency as a function of collector width, collector concentration has been verified by device simulator, ATLAS.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.724-729
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• 2007

The study is a structure analysis by applying the output torque and tangential force on 47 ton excavator drive motor gear carrier. The finite element analysis for 3D model is performed by ABAQUS/Standard. We made an estimate by evaluating the results of the finite element analysis.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.899-902
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• 1999

본 논문에서는 다수 반송자에 의해 일어나는 산란현상을 고려한 반송자-반송자 산란(CCS) 이동도 모델을 구현하였다. 구현된 CCS 이동도 모델을 검증하기 위해 N/sup ＋/P 접합 다이오드에 대해 모의실험 한 후 MEDICI와 비교한 결과 장벽전위인 0.9〔V〕 미만과 이상에서 각각 2%와 6% 정도의 상대오차를 보였다. BJT의 콜렉터에 30〔V〕를 인가한 후 베이스 전압을 0.8〔V〕까지 증가시켜 모의실험 한 결과 베이스 전압베이스 전류 및 베이스 전압-컬렉터 전류 특성은 각각 4.41%, 6.10%의 최대 상대오차를 보였다.