• 한국주조공학회지
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• 제27권3호
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• pp.115-119
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• 2007

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 춘계연구발표회 논문개요집
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• pp.62-63
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• 2002

No Abstract, See Full Text

• Bulletin of the Korean Chemical Society
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• 제21권11호
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• pp.1133-1137
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• 2000

Gibbs ensemble Monte Carlo simulations were performed to calculate the vapor- liquid coexistence properties for the binary mixtures $CO_2/C_3H8$, $CO_2/CH_3OCH_3$, and $CO_2/CH_3COCH_3.$ For all the molecules the potential between sites in different molecules was simply calculated by the Lennard-Jones potential. Density of the mixture, composition of the mixture, the pressure-composition diagram, the chemical potential of component, and the radial distribution function were calculated at vapor- liquid equilibrium. The composition and the density of both vapor and liquid from simulation agreed considerably well with the experimental values over a wide range of pressures. The radial distribution functions in the liquid mixtures showed that $CO_2$ molecules tended to form cluster with each other and $C_3H8$ molecules also aggregated each other due to the weak interaction between $CO_3$ and $C_3H8$ molecule. However the interaction potentials between the same components were similar to those between the different components in the liquid mixtures $CO_2/CH_3OCH_3$ and $CO_2/CH_3COCH_3$.

• 설비공학논문집
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• 제18권8호
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• pp.641-648
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• 2006

In this study, a two-stage phase-separate cycle was investigated analytically to improve the performance of the $CO_2$ system in the cooling mode. The simulation results were verified with the measured data. The predictions using the simulation model were consistent with the measured data within ${\pm}20%$ deviations. The performance of the modified $CO_2$ system with the two-stage phase-separated cycle was analyzed with the variations of outdoor temperature and EEV opening. The cooling COP decreased with the increase of compressor frequency. The highest COP was 2.7 at compressor frequencies of 30 Hz and 30 Hz for the first and second compressors, respectively. In addition, the cooling COP increased by 9.3% with an application of optimum control of the first and second-stage EEV openings.

• 대한조선학회논문집
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• 제52권4호
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• pp.330-337
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• 2015

When a tower crane is carried by a transporter in shipyard, the height and length of the tower crane should be adjusted to meet the safety guidelines. Since the guidelines came from the field experience, the safety limitation needs to be analyzed by a computer simulation. In this paper, modeling methods are addressed to implement the appropriate transportation simulation of a tower crane. For the relation between the tower crane and the transporter, normal contact force, friction force, and kinematic constraints are compared. Assignment of relevant linear acceleration and angular velocity is considered for the transporter to start or move on an inclined ground surface. By using the examined modeling methods, the dynamic motion of tower crane transportation is analyzed by a dynamic simulation program, and comparison between the simulation result and analytic solution is made to verify the feasibility of the modeling methods.

• International Journal of Air-Conditioning and Refrigeration
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• 제17권2호
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• pp.52-60
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• 2009

The purpose of this research is to develop high efficiency plastic plate heat exchangers which can be substituted for conventional aluminum plate heat exchangers. Four simulation models of plastic plate heat exchangers are designed and simulated: that is, flat plate type, turbulent promoter type, corrugate type and dimple type heat exchanger. The flat plate type is designed as the reference model in order to evaluate how much thermal performance increases. The turbulent promoter type is fabricated with cylindrical-type vortex generators and rib-type turbulent promoters. The corrugate type is obtained from the conventional stainless steel compact heat exchangers, which are called the herringbone-type compact heat exchangers. The dimple type has a number of dimples on its surface. In this study, the flow and heat transfer characteristics of the plastic plate heat exchanger are investigated using numerical simulation and compared with experimental results. Numerical simulation is carried out using the FLUENT code. The flows are assumed as a three-dimensional, incompressible and turbulent model. The computational analysis and experimental results both show that the friction coefficient and Nu number is highest in the corrugate type. The tendency of numerical simulation results is in good agreement with that of the experimental results.

• 한국가스학회지
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• 제15권3호
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• pp.31-38
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• 2011

본 연구에서는 미국 NIST의 Fire Dynamics Simulator (FDS) ver. 5.4.8을 이용하여 지하철 터널 안의 지하철에서 화재가 발생한 경우에 터널에 설치된 환기팬의 제연효과를 검증하였다. 시뮬레이션을 위해 서울 지하철의 실측 자료를 활용하여 지하터널과 지하철을 모델링 하였다. 이를 바탕으로 환기용량을 2.0~3.0 m/s 범위에서 변화시키면서 CO와 $CO_2$의 제거 효율을 예측한 결과, 0.5 m/s의 용량 증가에 의해 평균 35 % 이상의 제거효과가 있음을 확인하였다. 또한 FDS의 결과값이 전체 그리드 개수와 크기에 영향을 받는 점을 고려하여 정확한 결과값을 얻기 위해 FDS의 그리드 민감성을 검토하였다. 그리고 그리드 크기를 변화시켜 CO와 $CO_2$ 농도 산출값과 계산에 걸리는 시간을 비교한 결과를 바탕으로 최적의 그리드를 선정하여 시뮬레이션에 적용하였다.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.274-284
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• 2012

Recently, gasification technology for coal blended with biomass has been an issue. Especially, An advantages of coal blended with biomass are 1) obtaining high cold gas efficiency, 2) obtaining syn-gas of high-high heating value (HHV), and 3) controlling occurrence of $CO_2$. In this study, the efficiency and characteristic of 300 MW Shell type gasifier were predicted using CFD simulation. The CFD simulation was performed for biomass coal blending ratios of 0~0.2, 0.5, 1 and $O_2$/fuel ratios of 0.5~0.84. Kinetic parameters (A, $E_a$) obtained by $CO_2$ gasification experiment were used as inputs for the simulation. In results of CFD simulation, residence times of particle in 300MW Shell type gasifer presented as 7.39 sec ~ 13.65 sec. Temperature of exit increased with $O_2$/fuel ratio as 1400 K ~ 2800 K, while there is not an effects of biomass coal blending ratios. Considering both aspects of temperature for causing wall slagging and high cold gas efficiency, the optimal $O_2$/fuel ratio and blending ratio were found to be 0.585 and 0.05, respectively.

• 한국전자파학회논문지
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• 제29권2호
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• pp.118-127
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• 2018

본 논문에서는 합성개구레이다(Synthetic Aperture Radar: SAR) 장비의 성능 분석을 위하여 레이다 표적모의장치를 설계, 제작한 결과를 선보인다. 먼저 표적모의장치의 기능과 성능에 대해 설명하고, SAR 장비와 연동하기 위한 표적 시나리오 생성방법에 대해 설명하였다. 또한 제작된 표적모의장치를 이용하여 SAR 장비의 시간지연 값을 간단하고 정확하게 측정하고 보상하는 방법을 개발하였다. 시간지연이 보상된 SAR 장비와 표적모의장치를 이용하여 SAR 영상에서 점표적을 획득하고, IRF(Impulse Response Function) 분석을 통해 성능을 분석하였다. 그 결과, 방위방향 IRF의 PSLR(Peak to Side Lobe Ratio)은 -13.25 dB, 해상도는 0.49 m로 이론값과 매우 유사한 값을 보였다.

• 한국시뮬레이션학회논문지
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• 제19권2호
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• pp.157-164
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• 2010

우수하고 신뢰성 있는 통신 시스템의 개발을 위해 시스템에 대한 기능 검증과 성능 평가가 모두 필수적인데 반해 이들은 주로 형식 언어 도구를 이용한 기능 모델링과 전문 네트워크 성능 평가 도구에 의한 성능 모델링을 통해 개별적으로 수행되어 왔다. 그러나 한 시스템을 별도로 중복하여 모델링 하는 것은 비용의 증가와 모델 간 불일치를 가져오게 된다. 본 논문은 이 문제를 해결하기 위해 SDL-OPNET 코-시뮬레이션을 통해 SDL로 설계된 통신 프로토콜의 성능을 평가하는 통합 설계 기법을 제안한다. 제안 기법은 Tau의 환경함수와 OPNET의 외부시스템 모듈을 이용하는 코-시뮬레이션 시스템의 설계 방법을 제시한다. InRes 프로토콜이 예로 사용되어 제안 기법의 적용가능성과 효용성을 보여준다.