• Journal of the Korea Society for Simulation
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• v.8 no.4
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• pp.9-24
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• 1999

We describe a heterogeneous simulation framework, so called DEVS-HLA, in which conventional simulation models and the DEVS (Discrete Event System Specification) models are interoperable. DEVS-HLA conceptually consists of three layers: model layer, DEVS BUS layer, and HLA (High Level Architecture) layer. The model layer has a collection of heterogeneous simulation models, such as DEVS, CSIM, SLAM, and so on, to represent various aspects of a complex system. The DEVS BUS layer provides a virtual software bus, DEVS BUS, so that such simulation models can communicate with each other. Finally, the HLA layer is employed as a communication infrastructure, which supports several good features for distributed simulation. The DEVS BUS has been implemented on the HLA/RTI (Run-Time Infrastructure) and a simple example of a flexible manufacturing system has been developed to validate the DEVS-HLA.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.302-302
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• 2010

비정질 실리콘 박막 태양전지의 설계에 있어서 빛을 처음 받아들이는 p-layer는 전체적인 태양전지 특성에 큰 영향을 준다. 본 논문에서는 window layer의 gas flow rate 변화에 따른 특성이 태양전지에 미치는 영향에 대한 simulation을 수행하였다. 가변 조건으로는 window layer의 산소와 붕소 양에 따른energy bandgap과 conductivity 그리고 activation energy를 단계별로 변화시켜 simulation을 수행하였다. Simulation 결과 산소와 붕소의 양에 따른 window layer의 특성은 태양전지의 특성에 큰 영향을 끼친다. 본 연구는 simulation data를 기반으로 real device 제작하는데 큰 도움이 될 것이다.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.351-357
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• 2009

In this paper, we studied an efficient inter-working method in which QualNet network simulator can import WAVE channel model and physical layer simulation module pre-designed by Matlab tool. At first, we investigated physical layer and communication medium simply designed in QualNet, then we suggested practical method for QualNet network simulator to adopt different type of physical layer simulation module in which detailed multi-path fading channel model and IEEE802.11p communication modem are designed. This work should be applied to linked simulation between upper layer and lower physical layer for total simulation from higher layer to lower physical layer related to next generation DSRC/WAVE specification.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.426-432
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• 2004

Large-Eddy Simulation (LES) is applied for the simulation of compressible flat plate boundary with Reynolds number up to 5 X 10$^{5}$ . Numerical examples include shock/boundary layer interaction and boundary layer transition, aiming future application to the analysis of transonic fan/compressor cascades. The present LES code uses hybrid com-pact/WENO scheme for the spatial discretization and compact diagonalized implicit scheme for the time integration. The present code successfully predicted the bypass transition of subsonic boundary layer. As for supersonic turbulent boundary layer, mean and fluctuation velocity of the attached boundary, as well as the evolution of the friction coefficient and the displacement thickness both upstream and downstream of the separation region are all in good agreement with experiment. The separation point also agreed with the experiment. In the simulation of the shock/laminar boundary layer interaction, the dependence of the transition upon the shock strength is reproduced qualitatively, but the extent of the separation region is overpredicted. These numerical examples show that LES can predict the behavior of boundary layer including transition and shock interaction, which are hardly managed by the conventional Reynolds-averaged Navier-Stokes approach, although there needs to be more effort before achieving quantitative agreement.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.53-57
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• 2012

This paper is for accurately simulating the breakdown of MHEMTs with an InP-etchstop layer. 2D-Hydrodynamic simulation parameters are investigated and calibrated for the InP-epitaxy layer. With these calibrated parameters, simulations are performed and analyzed for the breakdown of devices with an InP-etchstop layer. In the paper, the impact-ionization coefficients, the mobility degradation due to doping concentration, and the saturation velocity for InP-epitaxy layer are newly calibrated for more accurate breakdown simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.277-280
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• 2008

Multi layer bellows are being manufactured for commercial vehicle because of the characteristic of high durability compared with single iaγor bellows used to passenger vehicle. Finite Element Method (FEM) study and optimization about single layer bellows are actively progressed, but FEM study about multi layer bellows which have gap between layer is rarely processed. Therefore, this article presents finite element modeling of multi layer bellows for the improvement of simulation reliability. For the shape optimization of multi layer bellows, design of experiment and Taguchi method are used.

• Computers and Concrete
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• v.31 no.1
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• pp.9-21
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• 2023

The published studies usually used analytical method, numerical methods or experimental method to determine the stress-strain state and displacement of the single-layer or multi-layer curved shell types, but with a small scale model. However, a full scale multi-layer doubly curved concrete shell roof model should be researched. This paper presents the results of the experiment and simulation analysis involving stress-strain state, sliding between layers, the formation and development of the full scale double-layer doubly curved concrete shell roof when this shell begins to crack. The results of the this study have constructed the load-sliding strain relationship; strain diagram; stress diagram in the shell layers; the N_x, N_y membrane force diagram and deflection of shell. Thisresults by experimental method on a full scale model of concrete have clarified the working of multi-layer doubly curved concrete shell roof. The experimental and simulation results are compared with each other and compared with the Sap2000 software.

• Journal of the Korean institute of surface engineering
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• v.43 no.2
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• pp.97-104
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• 2010

In this paper, we conducted MATLAB simulation using the reflectance formula and the Planck's black body radiation principle, for the purpose of identifying the opimum material and thickness of anti-reflective coating from double layered structures. We found that the optimum condition was obtained when refractive index of upper layer is 1.44 and that of lower layer is 2.29. As materials close to these refractive indices, $MgF_2$ as the upper layer and $HfO_2$, ZnS, $TiO_2$ as the lower layer were suggested. The best result in an average reflectance of 2.759% was obtained from a double layered structure of $MgF_2$ 94 nm/ZnS 55 nm.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.91-91
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• 2011

박막태양전지의 높은 효율개선을 위해 TCO층과 p-layer 사이에 buffer layer를 넣어 Voc와 FF를 개선하는 연구가 진행되고 있다. 이에 buffer layer의 활성화 정도를 높이기 위해 p-layer을 최적화 시키고자한다. 이 실험에서 a-Si:B에 N2O를 도핑시켜 Bandgap Energy 2.0 eV, Activation Energy 0.4 eV인 a-SiOx:B 막을 제작하여 buffer layer로 사용하였고 이 buffer layer에 의한 cell의 효율 향상을 최적화 하기위해 ASA simulation을 이용해 p-layer의 Bandgap Energy와 Activation Energy를 가변 하여 보았다. 실험결과 p-layer의 Bandgap Energy 1.95 eV에서 buffer layer와 p-layer사이에서의 barrier가 최소가 됨을 확인 할 수 있었고 Actication Energy 0.5 eV에서 가장 높은 Voc를 가짐을 알 수 있었다. 본 연구를 통해 p-layer의 Bandgap Energy 1.95 eV, Activation Energy 0.5 eV에서 buffer layer를 활성화시키기 위한 p-layer의 최적화 조건을 구현해 볼 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.46-47
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• 2008

Organic light-emitting diode is quick response speed, low power consumption and the self-interest has many advantages, such as insanity. So, organic light-emitting diode mechanism of light-emitting diode in order to more clearly understand the changes in the thickness of emitting materials for OLED characteristics of the simulation. emitting layer to a thickness of 10 [nm] ~ 100 [nm] changed the experiment, and hole transport layer 190 [nm] as a fixed. and emitting layer 10 [nm] ~ 100 [nm] to change the simulation results. Changes in the thickness of emitting layer gradually increased. depending on the emitting was 20 [nm] in the high 441 [lm / W] shows. and was gradually reduced. emitting layer 190 [nm] when fixed, hole transport layer, depending on changes in the thickness of 70 [nm] in the efficiency maximum value of 477 [lm / W], and was gradually reduced.