• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1339-1345
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• 2017

In the framework of the EU funded project NURESAFE, the subchannel code CTF and the neutronics code DYN3D were integrated and coupled on the NURESIM platform. The developments achieved during this 3-year project include assembly-level and pin-by-pin multiphysics thermal hydraulics/neutron kinetics coupling. In order to test this coupling, a PWR rod ejection transient was simulated on a MOX/UOX minicore. The transient is simulated using two different models of the minicore. In the first simulation, both codes model the core with an assembly-wise resolution. In the second simulation, a pin-by-pin fuel-centered model is used in CTF for the central assembly, and a pin power reconstruction method is applied in DYN3D. The analysis shows the influence of the different models on global parameters, such as the power and the average fuel temperature, but also on local parameters such as the maximum fuel temperature.

• 제어로봇시스템학회논문지
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• 제6권6호
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• pp.506-513
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• 2000

This paper proposes a path planning algorithm for dispensers to increase the productivity in printed circuit board assembly lines. We analyze the assembly sequence of the dispenser, and formulate it as an integer programming problem. The mathematical formulation can accomodate multiple heads and different types of heads through extended cost matrix. The TSP algorithms are then applied to the formulated problem to find the near-optimal solution. Simulation results are presented to verify the usefulness of the proposed scheme.

• 대한산업공학회지
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• 제17권1호
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• pp.59-73
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• 1991

In this paper, how to evaluate the assembly system was studied. The traction machine(TRM/C) is a kind of medium sized small quantity product. This work was performed on restriction of satisfying the customer's demand by simulating on the criteria of the queuing quantity in production system, the effectiveness of assembly machine and the average time spent on assembling. The problems about assembling were grasped through the analysis of products and process. The outputs of simulations that used SIMAN on four alternatives were evaluated on the basis of the average queuing quantity, the line effectiveness, the assembly time of a product and the production capacity.

• International Journal of Control, Automation, and Systems
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• 제5권2호
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• pp.192-199
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• 2007

This paper proposes a new printed circuit board (PCB) assembly planning method for multi-head surface mounters. We present an integer programming formulation for the optimization problem, and propose a heuristic method to solve the large NP-complete problem within a reasonable time. A dynamic programming technique is then applied to the feeder arrangement optimization and placement sequence optimization to reduce the overall assembly time. Comparative simulation results are finally presented to verify the usefulness of the proposed method.

• Journal of Communications and Networks
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• 제8권2호
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• pp.234-240
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• 2006

We study the dynamic burst assembly based on traffic prediction and offset and delay differentiation in optical burst switching network. To improve existing burst assembly mechanism and build an adaptive flexible optical burst switching network, an approach called quality of service (QoS) based adaptive dynamic assembly (QADA) is proposed in this paper. QADA method takes into account current arrival traffic in prediction time adequately and performs adaptive dynamic assembly in limited burst assembly time (BAT) range. By the simulation of burst length error, the QADA method is proved better than the existing method and can achieve the small enough predictive error for real scenarios. Then the different dynamic ranges of BAT for four traffic classes are introduced to make delay differentiation. According to the limitation of BAT range, the burst assembly is classified into one-dimension limit and two-dimension limit. We draw a comparison between one-dimension and two-dimension limit with different prediction time under QoS based offset time and find that the one-dimensional approach offers better network performance, while the two-dimensional approach provides strict inter-class differentiation. Furthermore, the final simulation results in our network condition show that QADA can execute adaptive flexible burst assembly with dynamic BAT and achieve a latency reduction, delay fairness, and offset time QoS guarantee for different traffic classes.

• 한국시뮬레이션학회논문지
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• 제31권3호
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• pp.23-34
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• 2022

철도차량은 제품의 특성상 일정한 수량의 차량이 결합되어 편성이 구성되며, 프로젝트는 복수의 편성을 고객에게 납품하는 것으로 계약이 이뤄지는데 만일 납기를 지키지 못하면 생산자가 지체보상금을 고객에게 지불해야 한다. 이 논문에서는 부품의 결품이 발생하는 상황에서 흐름라인 방식으로 운영되는 철도차량 의장공장의 운영전략에 대해 시뮬레이션을 이용하여 분석한다. 만일 부품의 결품이 발생한다면 조립공정의 특성상 후속 조립공정이 진행될 수 없다. 따라서 이 문제를 해결하기 위해 부품의 결품이 발생했을 때 조립작업을 수행하는 3가지 전략을 제시하였고, 인건비와 지체보상금을 합한 총 비용이 전략에 따라 어떻게 변화되는지 비교하였다.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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• pp.683-688
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• 2006

We have developed a program for generating shotgun data sets from known genome sequences. Generation of synthetic data sets by computer program is a useful alternative to real data to which students and researchers have limited access. Uniformly-distributed-sampling clones that were adopted by previous programs cannot account for the real situation where sampled reads tend to come from particular regions of the target genome. To reflect such situation, a probabilistic model for biased sampling distribution was developed by using an experimental data set derived from a microbial genome project. Among the experimental parameters tested (varied fragment or read lengths, chimerism, and sequencing error), the extent of sequencing error was the most critical factor that hampered sequence assembly. We propose that an optimum sequencing strategy employing different insert lengths and redundancy can be established by performing a variety of simulations.

• Fibers and Polymers
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• 제4권1호
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• pp.15-19
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• 2003

The self-assembly of asymmetric ABC triblock copolymers in the ordered structure is investigated using an isothermal-isobaric molecular dynamics simulation. Unlike symmetric A BC triblock copolymers, more fascinating mophologies are observed in asymmetric ones because of a larger difference of incompatibility between the components. Various modes of self-assembly in assymmetric ABC triblock copolymers are also observed depending on the block composition. When the composition of block A Is changed from 0.125: to 0.25 at the same $f_B$ : 0.25, the morphological transition from the “cylinder in cylinder” to “cylinders at cylinder” structure is observed in the simulation. In the case of ABC triblocks with $f_B$=0.5, a lamellar-type structure is changed to a cylinder-type structure with increasing the length of block A. When the midblock length increases further to $f_B$=0.625, the “spheres on cylinder” structure is observed in both the $A_{10}$$B_{50}$$C_{20}$ and $A_{20}$$B_{50}$$C_{10}$ triblocks. From these results, the phase diagram of ABC triblock copolymers can be constructed.

• 한국시뮬레이션학회논문지
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• 제16권2호
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• pp.65-74
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• 2007

가상생산기술은 신제품의 개발, 새로운 장비 개발 및 새로운 제조시스템 개발에 유용한 도구이며, 특히 3D 시뮬레이션 기술은 가상생산의 핵심기술이다. 3D 시뮬레이션 기술은 기계적 시뮬레이션 기술과 이산사건 시뮬레이션 기술로 구분할 수 있다. 본 논문에서는 휴대폰 카메라에 장착되는 렌즈모듈 조립을 생산하는 국내 회사의 사례를 소개한다. 이 회사에서는 렌즈모듈 조립공정을 현재 수작업으로 하고 있는데 자동화시스템을 개발하기로 결정하였으며 이를 위해 3D 시뮬레이션 기술을 도입하기로 하였다. 3D 시뮬레이션 기술은 시스템 개념설계단계에서부터 적용이 되었는데, 단위 장비 개발을 위해서는 $CATIA^{(R)}$와 $IGRIP^{(R)}$이 활용되었으며, 시스템 설계를 위해서는 이산사건 시뮬레이션 도구인 $QUEST^{(R)}$가 활용되었다. 논문의 목적은 새로운 자동화 설비의 기술적. 경제적 타당성을 검증하는 것이다. 개발결과 takt time 이 기존의 수작업에 비해 4분의 1 수준으로 감소되었으며, 이에 따른 작업자 인원도 대폭 감소되었다.

• 한국시뮬레이션학회논문지
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• 제21권4호
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• pp.75-80
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• 2012

본 논문에서는 가상현실 기술을 기반으로 정비성 모의 시스템에 대한 개발 기술 및 적용 사례에 대해 기술하였다. 정비성 모의를 위해 가상현실 장비를 기반으로 한 몰입형 시뮬레이터가 개발되었으며, 상용 소프트웨어인 DELMIA를 활용한 조립 시뮬레이션이 공대지 유도무기를 대상으로 수행되었다. 개발된 시스템은 설계 단계에서 군수지원 요소 개발에 다양하게 활용이 가능하였으며 효용성을 확인할 수 있었다.