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The High Order WENO Scheme on the Adaptive Mesh
Daeki Yoon,Hongjoong Kim,Woonjae Hwang 한국산업응용수학회 2009 한국산업응용수학회 학술대회 논문집 Vol.2009 No.5
The paper is concerned with the high order accurate computational method on hyperbolic conservationa law using weighted essentially non-oscillatory (WENO) scheme when nonuniform grids are adaptively introduced near a shock or a contact discontinuity. We apply the WENO scheme on nonuniform spatial grids, and high level of mesh refinement is introduced only in the region where more accurate computation is required such as points of discontinuity or sharp transition layer. The scheme estimates cell averages using the ENO-based interpolation when cells are merged or split. Numerical experiments show that the suggested method preserve the order of the WENO method on the adaptive mesh and that the method can be performed for a sufficiently long time with less computational cost.
김대기(Daeki Kim),문영세(Youngse Mun) 한국정책분석평가학회 2006 政策分析評價學會報 Vol.16 No.1
Northeast Asia has the most military manpower in the world, and becomes an arena of military force and arms competition. Korea holds the 6th position in military manpower and the 11th position in military expenditure. But the military threat to national security is relative. This paper is to analysis the optimum efficiency of limited national defense investment by comparing Korea to the existence threat and a latency threat in the military force and national defence budget. It constructed the integrated evaluation model of comparing military power and the defense budget. Simple statistic approach was chosen in military power evaluation, and total military expenditure with war potential expense was chosen in comparing defense budget of northeast Asia. In conclusion, Korea was evaluated not to make a comparative high position field to the existence threat or a latency threat, to have a defective defense budget structure resulting in widening the military force difference. So with the predicting future defense budget, some suggestions were made in military power construction and defense budget apportionment.
Lee, Daeki,Vu, Hung,Sun, Hengyang,Pham, Thuy Linh,Nguyen, Dang Thanh,Lee, Jong-Sook,Fisher, John G. Elsevier 2016 CERAMICS INTERNATIONAL Vol.42 No.16
<P><B>Abstract</B></P> <P>Single crystals of 0.8(Na<SUB>0.5</SUB>Bi<SUB>0.5</SUB>)TiO<SUB>3</SUB>-0.2SrTiO<SUB>3</SUB> were grown for the first time by the Solid State Crystal Growth technique (SSCG). [001], [110] and [111]-oriented seed crystals of SrTiO<SUB>3</SUB> were buried in 0.8(Na<SUB>0.5</SUB>Bi<SUB>0.5</SUB>)TiO<SUB>3</SUB>-0.2SrTiO<SUB>3</SUB> powder which was then pressed to form samples. Samples were sintered at 1200°C for 20h and single crystals of 0.8(Na<SUB>0.5</SUB>Bi<SUB>0.5</SUB>)TiO<SUB>3<SUP>-</SUP> </SUB>0.2SrTiO<SUB>3</SUB> grew on the seeds. The direction of least growth was [001] (∼60µm), with the [110] and [111] directions having growth distances of ∼200µm. Chemical composition of the crystals was analyzed by Electron Probe Micro Analysis and found to be close to the nominal composition, with some volatilization of Na and Bi. Micro-Raman scattering showed that the single crystal has the (Na<SUB>0.5</SUB>Bi<SUB>0.5</SUB>)TiO<SUB>3</SUB> structure. In order to measure the electrical properties, a single crystalline thick film of 0.8(Na<SUB>0.5</SUB>Bi<SUB>0.5</SUB>)TiO<SUB>3</SUB>-0.2SrTiO<SUB>3</SUB> was grown on a [001]-oriented Nb-doped SrTiO<SUB>3</SUB> seed crystal. The single crystalline thick film showed relaxor-like relative permittivity vs. temperature behavior and polarization – electric field hysteresis loops for a lossy ferroelectric material.</P>
김대기(Daeki Kim),조한홍(Hanhong Jo) 한국유통학회 2002 流通硏究 Vol.7 No.1
지금까지의 자동차 시장의 물류 관련 연구는 조달물류 부분에 치중된 반면, 완성차 판매 물류에 대한 연구는 미진한 상태이다. 이에 본 연구는 국내 완성차 물류에 대한 연구의 시발점으로써, 국내 자동차 조립업체의 완성차 물류 네트워크가 안고 있는 문제점을 Location strategy, Inventory strategy 그리고 Transportation strategy의 세 가지 차원에서 살펴보고, 이러한 문제점들을 해결할 수 있는 대안을 물류 네트워크 재설계라는 전략적 차원에서 제시하였다. 그리고 이러한 대안을 실행하기 위한 3가지 시나리오를 제시하였다. 인터뷰, 현지방문 및 내부자료조사 자료를 근간으로, 국내 완성차 물류의 문제점으로는 물류 거점 중복, 비효율적인 배달탁송구조, 재고 저장공간 부족, 재고 품질 저하, 또한 낮은 수배송 효율 등이 있음을 확인하였다, 본 논문은 이러한 문제들을 해결하기 위하여 hub-and-spoke 시스템의 도입, 물류 거점의 통합, 주차빌딩/자동창고의 도입. 운송수단의 다양화 등의 전략적인 대안들을 제시하였으며, 현실 적용 가능하고 그 효과가 가장 클 것으로 기대되는 세 가지 전략적 시나리오를 제시하였다. 제 1시나리오는 국토 중앙에 hub를 구축하여 제조출고가 담당하지 못하는 부분을 키버하는 ‘중앙 hub 도입’ 시나리오이고 제 2시나리오는 수요가 가장 많이 발생하는 수도권에 hub를 구축하여 수도권지역의 서비스 강화 및 향후 대륙진출의 전초기지로써 활용하는 ‘수도권 hub 도입’ 시나리오이다. 마지막 시나리오는 권역별 출고센터를 제조출고 위주로 통합하는 ‘권역별 출고센터 통합’ 시나리오이다. Many of logistics-related research in automobile industry has focused on inbound logistics and procurement. Research into outbound logistics is relatively few. As a starting research into outbound logistics in automobile industry, this paper examined its logistics network problems with three aspects - location strategy, inventory strategy and transportation strategy. We proposed alternatives of logistics network design resolution, and presented three practical scenarios based on those alternatives. Based on interview, on - site visit and internal data collection processes, we identified major domestic outbound logistics problems such as redundant logistics bases, inefficient delivery policy, insufficient inventory capacity, inventory stock quality deterioration, inefficient transportation system, and etc. In order to cope with those problems, we proposed such strategic alternatives as introduction of hub-and-spoke system, integration of logistics bases, introduction of (automatic) parking building, diversification of transportation mode, and etc. At the same time, we constructed three practically executable scenarios based on those ideas. The first is "Center Hub" scenario, the second is "Metropolitan Hub" scenario. The third and last scenario is "Regional Consolidation of Warehouses (distribution centers)".
홍대기(Daeki Hong),이형철(Hyeongcheol Lee),곽재호(Jaeho Kwak) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper presents a mathematical model and simulation program of a train with regenerative braking system by using Matlab/Simulink in the energy generation, consumption and transfer point of view. This paper also determines the specifications of each component of the train by using the developed program. The train model and simulation program consist of the speed profile of the train, longitudinal dynamics of the train, wheel dynamics with brake system, and electric system such as the motor/generator and the energy storage sytsem. This paper also provides observation of the energy consumption and regeneration ratios of the energy storage equipped train. The simulation results are compared with the test results to verify the simulation program.