• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.59-63
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• 2009

The UTP cable has been widely used, recently it is being developed for use in the UHF frequency band. One important characteristic of the UTP cable is NEXT. This research is to develop a pitch selection technique for an UTP cable which leads to a satisfactory NEXT. The transmission line model involving mutual inductances and capacitances between line pairs is used, and the simulation was carried out for frequencies from 1 MHz to 600 MHz. With respect to the worst margin of the NEXT for a Cat. 6 cable the simulation and measurement results show a good agreement.

• Clean Technology
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• v.9 no.2
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• pp.81-85
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• 2003

A simple method of isotherm determination for HPLC is discussed. The equilibrium-dispersive model describing the behavior of elution peaks in HPLC for single component is solved numerically by using PDE solver Macsyma$^{(R)}$(Macsyma Inc., Arlington, MA, USA.) and compared to the experimental data obtained in overloaded isocratic chromatography with caffeine as model species. The effect of sample concentration and flow velocity on the band profiles of elution peaks are described.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.213-216
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• 2009

유한요소모델개선기법은 계측된 동특성을 모사하는 구조해석모델을 구하는 방법으로서 손상탐지 및 구조건전도감시를 위해 효과적으로 이용될 수 있다. 유한요소모델개선기법에는 다양한 종류의 동특성데이터가 사용될 수 있는데, 본 연구에서는 고유진동수와 모드형상을 사용한 경우와 고유진동수와 주파수응답함수를 사용한 경우를 각각 사용해 실험실 규모의 구조물의 손상 위치 및 손상정도를 추정하였다. 4층 철골조의 골조구조물로서 진동대를 이용하여 원구조물에 백색잡음 가진실험을 실시한 후 손상의 모사를 위해 1층 부분의 보 부재를 작은 단면의 부재로 교체하고 동일한 실험을 반복하였다. 보 부재 교체 전 후에 계측된 데이터와 두 종류의 모델개선기법을 각각 적용하여 손상탐지를 실시한 후 그 정확도를 분석하였다.

• Journal of computational fluids engineering
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• v.4 no.3
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• pp.63-70
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• 1999

A Direct simulation Monte-Carlo (DSMC) code is developed, which employs the Monte-Carlo statistical sampling technique to investigate hypersonic rarefied gas flows accompanying chemical reactions. The DSMC method is a numerical simulation technique for analyzing the Boltzmann equation by modeling a real gas flow using a representative set of molecules. Due to the limitations in computational requirements. the present method is applied to a flow around a simple two-dimensional object in exit velocity of 7.6 km/sec at an altitude of 90 km. For the calculation of chemical reactions an air model with five species (O₂, N₂, O, N, NO) and 19 chemical reactions is employed. The simulated result showed various rarefaction effects in the hypersonic flow with chemical reactions.

• Journal of computational fluids engineering
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• v.10 no.3 s.30
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• pp.63-69
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• 2005

The COMS, the first meteorological geostationary satellite in Korea, is under development by KARI. The radiator size and the heater power for the thermal control of COMS are calculated using an analytic method. The total radiator area of $4.85\;m^2$ and the total heater power of 794.77 W are determined at a conceptual design of COMS. The commercial software, SINDA and TRASYS, are utilized in order to compare and verify the analytic results. The results of on-orbit numerical simulation of cold and hot cases show that the radiator size and heater power obtained from the analytic method are appropriate to maintain COMS equipments within required temperature ranges.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.464-467
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• 2008

폐차잔재물중 가연성 성분을 시멘트 제조공정의 열원으로 활용하기 위한 연구가 현재 활발히 진행 중에 있다. 그러나 이러한 폐차잔재물을 시멘트 제조공정의 보조열원으로 사용하기 위해서는 에너지활용에 대한 경제성 및 환경기준과 더불어 시멘트 제조공정의 안정적 조업조건에 대한 검토가 이뤄져야만 하며 특히 폐차잔재물의 연소시 시멘트 제조공정에서의 염소물질의 거동특성에 대한 연구가 반드시 선행되어야만 한다. 따라서 본 연구에서는 이러한 폐차잔재물의 시멘트 제조공정에 대한 열원활용의 최적조건을 도출하고자 현장적용 전 킬른내 염소성분의 제어를 위한 Bypass unit의 Cyclone에 대한 전산모사연구를 수행하였으며 이러한 전산모사결과를 바탕으로 실제 시멘트 제조공정에 대한 폐차잔재물의 현장적용 실험을 수행하였다. 또한 본 연구로부터 시멘트 제조공정에 대한 폐차잔재물의 열원활용 가능성을 확인할 수 있었으며 폐차잔재물의 투입시 시멘트 제조공정의 안정적 조업조건을 확보할 수 있었다.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.343-348
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• 2007

Molecular dynamics study of thermal NIL (Nano Imprint Lithography) process is performed to examine stamp-resist interactions. A layered structure consists of Ni stamp, poly-(methylmethacrylate) thin film resist and Si substrate was constructed for isothermal ensemble simulations. Imposing confined periodicity to the layered unit-cell, sequential movement of stamp followed by NVT simulation was implemented in accordance with the real NIL process. Both vdW and electrostatic potentials were considered in all non-bond interactions and resultant interaction energy between stamp and PMMA resist was monitored during stamping and releasing procedures. As a result, the stamp-resist interaction energy shows repulsive and adhesive characteristics in indentation and release respectively and irregular atomic concentration near the patterned layer were observed. Also, the spring back and rearrangement of PMMA molecules were analyzed in releasing process.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.403-406
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• 2006

본 연구에서는 양극의 two-phase simulation 모델을 확립하고 GDL 물성과 작동조건이 전지성능에 미치는 영향에 대해 시행하였다. 모델로는 Multi-phase $mixture(M^2)$ 모델을 사용하였는데 이 모델은 각 상의 balance식을 하나의 mixture-phase식으로 통합하여 수학적 계산이 용이할 뿐만 아니라 실제 전지 성능에 매우 근사하여 신뢰성성도 확보할 수 있었다. 최적의 GDL 구조와 작동조건을 규명하기 위해 기체투과도, 접촉각, 기공도, 기체 공급가스 차이에 따른 전지 성능 분석을 시행하였는데 그 결과 모든 파라미터들이 증가할수록 비례적으로 전지 성능이 증가하였다. 기체 공급가스>기공도>>접촉각>기체투과도 순으로 전지에 미치는 영향이 큰 것으로 나타났다.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1199-1204
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• 2003

The 3D simulations of the shielding concrete and the Rotary Specimen Rack(RSR) in the Korea Research Reactor-1&2(KRR-1&2) were carried out in present work. Four main dismantling processes, which are the removal of the RSR, reactor core region, beam tube, and thermal column and activated concrete, were selected for the graphic simulation by the consideration of the activation, worker training, work difficulty and so on. On the basis of these, we constructed their 3D CAD models and then drawn and reviewed their dismantling processes. In this study, the 3D simulation results of the shielding concrete and the RSR among main components are also presented and discussed.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.492-495
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• 2008

As the obesity patients increase recently, breath disease such an OSA(obstructive sleep apnea) is also increasing. When the breath disease occurs, the risk comes to be high. Dependence degree the PAP(positive airway pressure) is also coming to be high. The mechanical simulator is composed cylinder, valve, ball screw and the motor that they correspond to the lung and airway, the diaphragm of the human. In order to confirm the characteristic of the motor and the valve, it accomplished an test. The simulator traces breath pattern against the normal breath and the OSA.