• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.4
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• pp.421-431
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• 2017

A process-centric simulation modeling method has been proposed to define a shipbuilding simulation model. Existing modeling methods have limitations for expressing various production information for a shipyard. The advanced process-centric modeling method proposed in this paper offers an improvement, effectively representing production information and constraints for a shipyard. To achieve this, a method and diagram components to define a process-centric simulation model in detail have been suggested. The modeling method can assign priorities when multiple products and facilities are assigned to the process. And layer concept was applied to express simulation model with hierarchical structure. To verify the effectiveness of the modeling method, comparative analysis has been performed and the actual shipbuilding process has been modeled using the proposed method. When a single facility was used for various purposes, we found that the proposed method was more advantageous than existing methods. As a result, it was possible to express constraints and flows that were difficult to identify with existing process-centric simulation modeling methods, and the methods were improved for use in shipyard production planning verification simulations.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.44 no.10
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• pp.56-67
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• 2015

에너지절감의 원리는 공정간 에너지의 균형, 운전 최적화, 그리고 고효율에너지설비 교체이다. 이중 효과가 가장 큰 것은 공정간 에너지 균형을 달성하는 것이며, 그 대표적인 방법이 공정에서 발생하는 미활용에너지를 발굴하여 적절한 변환을 거쳐 다른 공정의 입력으로 재활용하는 것이다. 이를 위해서 기존의 공정을 "에너지 흐름" 중심으로 재해석하고 에너지시스템을 모델링하며 미활용에너지의 재활용 방안을 도출하여 그 성과를 예측할 수 있어야 한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.267-267
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• 2012

최근 국내 반도체 장비 업체들에 의해서 차세대 반도체용 450 mm 웨이퍼 공정용 장비 개발이 진행 중에 있다. 반도체 산업은 계속해서 반도체 칩의 크기를 작게 하고, 웨이퍼 크기를 늘리면서 웨이퍼 당 칩수를 증가시켜 생산성을 향상해오고 있다. 현재 300 mm 웨이퍼에서 450 mm 웨이퍼를 도입하게 되면, 생산성 뿐만 아니라 30%의 비용절감과 50%의 cycle-time 단축이 기대되고 있다. 장비에 대한 이해와 공정에 대한 해석 능력을 위해 비용과 시간이 많이 들기 때문에 최근 컴퓨터를 활용한 수치 모델링이 진행되고 있다. 또한, 수치 모델링은 실험 결과와의 비교가 필수적이다. 본 연구에서는 450 mm 웨이퍼 공정용 장비의 전자밀도를 cut off probe를 통해 100 mTorr에 서 Ar 플라즈마를 파워에 따라 측정했다. 13.56 MHz 200 W, 500 W, 1,000 W로 입력 파워가 증가하면서 웨이퍼 중심에서 $6.0{\times}10^9#/cm^3$, $1.35{\times}10^{10}#/cm^3$, $2.4{\times}10^{10}#/cm^3$로 증가했다. 450 mm 웨이퍼 영역에서 전자 밀도의 불균일도는 각각 10.31%, 3.24%, 4.81% 였다. 또한, 이 450 mm 웨이퍼용 CCP 장비를 축대칭 2차원으로 형상화하고, 전극에 13.56 MHz를 직렬로 연결된 blocking capacitor ($1{\times}10^{-6}$ F/$m^2$)를 통해 인가할 수 있도록 상용 유체 모델 소프트웨어(CFD-ACE+, EXI corp)를 이용하여 계산하였다. 주요 전자-중성 충돌 반응으로 momentum transfer, ionization, excitation, two-step ionization을 고려했고, $Ar^+$와 $Ar^*$의 표면 재결합 반응은 sticking coefficient를 1로 가정했다. CFD-ACE+의 CCP 모델을 통해 Poisson 방정식을 풀어서 sheath와 wave effect를 고려하였다. Stochastic heating을 고려하지 않았을 때, 플라즈마 흡수 파워가 80 W, 160 W, 240 W에서 실험 투입 전력 200 W, 500 W, 1,000 W일 때와 유사한 반경 방향의 플라즈마 밀도 분포를 보였다. 200 W, 500 W, 1,000 W일 때의 전자밀도 분포는 수치 모델링과 전 범위에서 각각 10%, 3%, 2%의 오차를 보였다. 450 mm의 전극에 13.56 MHz의 전력을 인가할 때, 파워가 증가할수록 전자밀도의 최대값의 위치가 웨이퍼 edge에서 중심으로 이동하고 있음을 실험과 모델링을 통해 확인할 수 있었다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.4
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• pp.151-158
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• 2014

In this paper, we introduce an inference system using hard scatter partition method and model the nonlinear process. To do this, we use the hard scatter partition method that partition the input space in the scatter form with the value of the membership degree of 0 or 1. The proposed method is implemented by C-Means clustering algorithm. and is used for the initial center values by means of binary split. by applying the LBG algorithm to compensate for shortcomings in the sensitive initial center value. Hard-scatter-partitioned input space forms the rules in the rule-based system modeling. The premise parameters of the rules are determined by membership matrix by means of C-Means clustering algorithm. The consequence part of the rules is expressed in the form of polynomial functions and the coefficient parameters of each rule are determined by the standard least-squares method. The data widely used in nonlinear process is used to model the nonlinear process and evaluate the characteristics of nonlinear process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2075-2082
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• 2006

This paper presents modeling and optimization techniques for hish efficiency solar cell process on single-crystalline float zone (FZ) wafers. Among a sequence of multiple steps of fabrication, the followings are the most sensitive steps for the contact formation: 1) Emitter formation by diffusion; 2) Anti-reflection-coating (ARC) with silicon nitride using plasma-enhanced chemical vapor deposition (PECVD); 3) Screen-printing for front and back metalization; and 4) Contact formation by firing. In order to increase the performance of solar cells in terms of efficiency, the contact formation process is modeled and optimized using neural networks and genetic algorithms, respectively. This paper utilizes the design of experiments (DOE) in contact formation to reduce process time and fabrication costs. The experiments were designed by using central composite design which consists of 24 factorial design augmented by 8 axial points with three center points. After contact formation process, the efficiency of the fabricated solar cell is modeled using neural networks. Established efficiency model is then used for the analysis of the process characteristics and process optimization for more efficient solar cell fabrication.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.25-30
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• 2001

본 논문은 SimPlus 3D를 이용한 생산시스템 공정개선 시뮬레이션 모델개발 프로젝트 수행 시 제안되었던 생산시스템 공정분석 및 개선사항을 SimPles 3D 모델을 중심으로 SimPlus 3D의 제품특징과 활용사례로 소개하고자 한다. SimPlus 3D는 범용 그래픽 시뮬레이션 소프트웨어로서 자동화 공정의 설비, 제어 운영에 걸친 다양한 요소를 모델링 할 수 있으며 구축된 시뮬레이션 모델을 이용하여 사용자가 원하는 결과척도를 상세하게 제시해 준다. 따라서 SimPlus 3D는 생산라인 개선작업에 있어서도 새로운 형태의 공정배치나 라인구성을 현장적용 전에 시뮬레이션 모델로 개발하여 도입효과를 정량적으로 산출할 수 있으며, 다양한 대안들을 적은 시간과 비용으로 평가할 수 있다. 본 논문에서는 SimPlus 3D를 이용한 생산시스템 공정개선 시뮬레이션 모델개발 사례로 A사의 제품 생산공정 중 일부 자동화공정 제어알고리즘 분석 사례를 소개하였다.

• Membrane Journal
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• v.20 no.1
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• pp.29-39
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• 2010

This study focuses on the modeling of DMFC to predict the characteristics and to improve its performance. This modeling requires deep understanding of the design and operating parameters that influence on the cell potential. Furthermore, the knowledge with reference to electrochemistry, transport phenomena and fluid dynamics should be employed for the duration of mathematical description of the given process. Considering the fact that MEA is the nucleus of DMFC, special attention was made to the development of mathematical model of MEA. Multiscale modeling is comprised of process modeling as well as a computational fluid dynamics (CFD) modeling. The CFD packages and process simulation tools are used in simulating the steady-state process. The process simulation tool calculates theelectrochemical kinetics as well as the change of fractions, and at the same time, CFD calculates various balance equations. The integrated simulation with multiscal modeling explains experimental observations of transparent DMFC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2851-2858
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• 2011

The schedule management in construction project have been performed independently by two method, WBS base management and CBS based management, However, the integrated management model is needed according to efficiency of construction project management and introduction of new EVMS system of KOREA government. For this purpose, interworking database system is designed through efficient modeling of WBS based management data and CBS based management data and relation establishment between entities in this paper. WBS based management DB consists of 4 entities and CBS based management DB consists of 3 entity and one of the 4 WBS DB entities is used to play interworking role between WBS and CBS, Also, attributes of all entities are well defined so that data consistency, integrity and newest are guaranteed. The designed interworking database model was realized using Nex-Pert Pro and the efficiency of data interworking was proved.

• Journal of the Korean Society of Safety
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• v.16 no.1
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• pp.88-93
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• 2001

This study discusses frequency analysis based on autoregressive (AR) time series model, and process characterization in orthogonal cutting of a fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using AR time series model. The resulting pattern vectors of AR coefficients are then passed to the feature extraction block. Inside the feature extraction block, only those features that are most sensitive to different types of cutting mechanisms are selected. The experimental correlations between the different chip formation mechanisms and AR model coefficients are established.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.3
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• pp.210-217
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• 2004

This paper presents a simulation methodology for the poly-silicon oriented TCAD(technology-CAD) system. A computer simulation environment for the poly-silicon processing has been set up with the proper adoption of the two-stream model for ion-doping, diffusion, and defects inside of grain and on the grain boundary. After the simulator calibration, simulation results for the poly-silicon diffusion has showed a good agreement with the SIMS data.