• 한국자동차공학회논문집
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• 제11권3호
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• pp.71-76
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• 2003

A numerical simulation of selective catalytic reduction (SCR) for NO with $NH_3$ is conducted over the $V_2O_5/TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalysts. The governing $NH_3$ and NO transport equations are considered by using the time-dependent FCT (Flux-Corrected Transport) algorithm. After a validating simulation for $NH_3$ step feed and shut-off experiments is analyzed, transient behavior of $NH_3$ and NO concentration in a SCR catalyst is investigated by changing such parameters as inflow $NH_3$ concentration, temperature of the catalyst, and $NH_3$/NOx ratios.

• 한국진공학회지
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• 제17권6호
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• pp.511-517
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• 2008

기체 방전의 수치적 시뮬레이션을 위하여 FE-FCT(Finite-Element Flux-Corrected Transport) 방법을 이용한 준 2차원 수치적 모델을 제시한다. 이 모델에서는 전자와 이온에 대한 1차원 연속방정식을 풀어 시 공간적으로 변하는 전하 분포를 계산하고, 공간 전하 분포에 의한 전기장의 변화는 2차원적 전하 분포를 고려하는 디스크 방법을 적용하여 푸아송(Poisson)방정식을 풀어 계산한다. 다양한 벤치마크 문제에 대해 계산한 결과는 이 모델의 정확성과 적용성을 잘 보여준다. 또 스트리머 방전에 대해 계산한 결과는 앞선 연구 결과와 잘 일치하는 것을 보여 준다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.200-208
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• 1999

In this paper, the corona discharge is analyzed by Finite Element Method(FEM) combined with Flux-corrected Transport(FCT) algorithm. In the previous papers, Finite Difference Method(FDM) combined with FCT was used. Usually in the FDM, the regionof interest is discretized with structured grids. But to refine local regions with same resolution, much more grids are required for the structured grids than for unstructured grids than for unstructured grids. Therefore, we propose the FEM-FCT method to simulate the corona discharge. The proposed method has good flexibility in model shape and can reduce the computational cost by the local refinement where the physical quantities have steep gradients. Using the proposed method, we study the streamer growth of parallel plate electrodes which is initiated by the low and high perturbation density. We find that the varying the initial density of perturbation has very little effect on the streamer propagation. And the corona discharge of the rod-to-plane electrode is simulated. On the surface of the rod electrode, the high concentration of the electric field gives rise to many number of streamer seeds. The strong axial streamer propagate to the plane electrode. The weaker non-axial streamer repel each other and stop growing more. The results are very similar to those of the papers which used the FDM-FCT method on structured grids. Thus we can conclude that the proposed FEM-FCT method is more efficient than the conventional FDM-FCT method by virtue of the reduction in computational grids number.

• Journal of Advanced Marine Engineering and Technology
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• 제22권5호
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• pp.693-701
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• 1998

This study presents result of comparison between two other numerical method method of char-acteristics(MOC) and Lax-Wendroff method(LWM) applied at wave action analysis of intake and exhaust pipe in terms of calculated pressure velocity and emitted noise in the time and the fre-quency domain by means of fast Fourier transform analysis. Particularly FCT(Flux Corrected Transport)scheme is appended to LWM to protest unaceptable overshoots occurring near discon-tinuity. The final conclusion of this study is that MOC should be replaced by a second order finite difference approach because of larger contributions due to high frequency components than the results from the method of characteristics. Clear benefits we can get by change are faster calcula-tion higher accuracy conservation of mass and consistent calculation method.

• 한국진공학회지
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• 제17권6호
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• pp.487-494
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• 2008

준 2차원 수치적 모델을 사용하여 침-평판(point-plane)형의 전극 사이에 있는 중간 압력 질소의 방전에 대한 시뮬레이션을 수행하였다. 이 모델에서는 전자와 이온에 대한 연속방정식을 풀어 시. 공간적으로 변하는 전하분포를 계산하고, 공간 전하 분포의 변화에 따라 결정되는 전기장은 푸아송 방정식을 풀어 얻는다. 연속 방정식은 FCT (Flux-corrected transport) 알고리즘과 FEM (Finite Element Method) 방법을 적용하여 수치적으로 다루어 졌다. 50Torr 압력에서의 질소 방전에 대한 시뮬레이션 결과는 중간 압력 질소 방전의 물리적 특성에 관한 상세한 이해를 제공한다. 또 계산 결과와 실험 결과[1]와의 비교는 정성적으로 잘 일치하는 것을 보여 준다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 가을 학술발표회 논문집
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• pp.76-83
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• 1995

Estimation of blasting behavior of explosives is prerequisite in the numerical analysis of blasting works. In this study, blasting pressure is estimated by the finite difference method using the Flux-Corrected Transport Algorithm. To formulate the behavior of blasting gas, the mass conservation equation, the moment conservation equation, the energy conservation equation and the ideal gas state equation are used. The simplified species conservation equation is included to simulate the behavior of reacting explosives. To verify the calculation, the Sod's shock tube problem, the strong shock problem and the reacting problem we used. Numerical results show that the shock wave can be captured by means of the FCT algorithm in the reacting and nonreacting states.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.565-567
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• 2000

In this paper, the discharge characteristics of AC PDP, one of the leading technologies currently under development for large-area flat displays, is computed by using Finite Element Method(FEM) combined with Flux-corrected Transport(FCT) algorithm. Up to now, many simulations of AC PDP have been mainly done by Finite Difference Method(FDM). But we simulated the AC PDP by using FEM-FCT method which discretizes the region of interest with unstructured grids. FEM-FCT method can reduce the computational cost because of refining locally where the physical quantities have steep gradients and is more efficient in solving discharge problems, such as a AC PDP. Results are presented in Ne-Xe(4%) gas mixture for a gas pressure of 400 Torr and as the discharge proceeds, the space and time variations of the electron and ion densities, potential and wall charges on the dielectric are described. Results from our simulation by FEM-FCT are similar to those from simulation by FDM and are more efficient in computational cost reduction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2044-2046
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• 1999

In this paper, the propagation of corona streamer was simulated using finite element method(FEM) combined with Flux-Corrected Transport(FCT) algorithm. To obtain more effective grid distribution, the adaptive mesh generation scheme was also employed. The employed adaptive scheme can refine the mesh where needed. In addition, it is possible to coarsen the unnecessarily dense mesh. Two models were analyzed with proposed method. And the results are shown.

• 한국진공학회지
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• 제13권3호
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• pp.132-138
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• 2004

대기압의 공기 중에서 코로나 방전 플라스마에 대한 특성을 연구하기 위해 wire-cylinder 형태의 반응로에서 FCT(flux-corrected transport) 알고리즘과 FEM(finite element method) 방법을 적용한 자체 모순이 없는 1차원 수치적 모델을 사용하였다. 코로나 방전 반응로에 펄스 전압과 직류 전압을 인가하였을 때, 플라스마 밀도의 분포를 계산하여 전압의 변화에 따른 플라스마 특성의 변화를 연구하였으며, 또한 반응로의 크기 변화에 따른 플라스마의 특성 변화를 연구하였다. 이 결과로 얻어지는 활동 반경(active radius)의 변화를 Peek의 실험값과 비교해 보았다. 이와 같은 코로나 방전 플라스마에 대한 수치적 계산 결과는 방전 과정에서 일어나는 물리적 특성을 잘 설명하여 환경오염 물질 제거를 위한 반응로의 최적 설계를 위해 유용하게 쓰일 수 있을 것이다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권5호
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• pp.232-237
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• 2001

The transition avalanche to streamer are presented in atmospheric pressure nitrogen. The results of two-dimensional simulation are obtained by using finite Elements Method combined with Flux Corrected Transport algorithm(FEM-FCT). We modeled the negative streamer which enables to propagate with out and with photoionization. The results of simulation without photoionization and with photoionization are compared. We show that photoionization plays important roles not only in streamer formation but also in streamer propagation.