• ETRI Journal
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• 제37권1호
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• pp.197-202
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• 2015

A smart grid is a modernized electrical grid that uses information about the behaviors of suppliers and consumers in an automated fashion to improve the efficiency, reliability, economics, and sustainability of the production and distribution of electricity. In the operation of a smart grid, demand side management (DSM) plays an important role in allowing customers to make informed decisions regarding their energy consumption. In addition, it helps energy providers reduce peak load demand and reshapes the load profile. In this paper, we propose a new DSM scheduling scheme that makes use of the day-ahead pricing strategy. Based on the Rubinstein-Stahl bargaining model, our pricing strategy allows consumers to make informed decisions regarding their power consumption, while reducing the peak-to-average ratio. With a simulation study, it is demonstrated that the proposed scheme can increase the sustainability of a smart grid and reduce overall operational costs.

• 한국건축시공학회지
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• 제13권4호
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• pp.360-371
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• 2013

Fast delivery of construction projects provides more value to project owners. Batch production, which is production not in single pieces, but in batches, is a common approach in repetitive construction projects such as multi-unit residential building construction projects. In batch production, the use of a small batch size allows the early start of subsequent activities, and thus can lead to early completion of projects. In addition to batch size, balance between productivities in construction activities can affect project duration. However, the impact of the balance between productivities with regard to their order on project duration has not been studied. The main goal of this study is to test a hypothesis, which is that the order of construction activities' unbalanced productivities affects the amount of time reduction that can be achieved by using a small batch size. A computer-based simulation model was developed, and five different cases were simulated to test the hypothesis. The conclusion of the simulation result is that the order of productivities does not affect the time reduction achieved by using a small batch size. It is expected that the findings of this study can help general contractors make decisions in terms of batch size.

• 대한산업공학회지
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• 제42권6호
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• pp.404-411
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• 2016

In footwear manufacturing systems, the upper parts of the shoes are manually sewed on a sub-line while bottom parts are produced by machines such as injection and molding machines on a sub-line before these two parts are combined into complete shoes on a final assembly line. The manual operations for the upper parts lead to a large variability in processing times, resulting in higher work-in-process inventory. In most footwear industries, production lines have been controlled by MRP-based push systems. Some industries attempt to introduce Kanban-based pull systems. This paper identifies the characteristics of the footwear manufacturing processes, and discusses the problems of the current control systems. As an operational alternative, a CONWIP-based control strategy is presented. Simulation experiments are performed to examine the performance of the control strategies.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.405-408
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• 2002

To support Internet traffic efficiently over ATM \networks, Guaranteed Frame Rate(GFR) has been proposed in tile ATM Forum to ensure minimum rate guarantees to VCs. In this paper, we proposed fuzzy logic based buffer management algorithm that provides MCR guarantee and fair sharing to GFR VCs. A key feature of proposed algorithm is its ability to accept or drop a new incoming packet dynamically based on buffer condition and load rate of VCs. This is achieved by using fuzzy logic controller for the production of a drop factor. Simulation result shows that proposed scheme significantly has improved fairness and TCP throughput compared with previous schemes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.987-992
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• 2005

Manufacturing companies should perform process planning and its evaluation concurrently with new product developments so that they can be highly competitive in the modern market. Process planners should make decisions in the manner of concurrent and collaborative engineering in order to reduce the manufacturing preparation time and cost when developing new products. Automated generation of analysis models from the integrated database, which contains process and material information, reduces time to prepare analyses and makes the models reliable. In this research, we developed a web-based system for concurrent and collaborative system for production flow analysis, using web, database, and simulation technology. An integrated database is designed to automatically generate analysis models from process and material plans without reworking the data. This system enables process planners to evaluate their decision fast and share their opinions with others easily. With this system, it is possible to save time and cost for assembly process and material planning, and reliability of process plans can be improved

• 한국건설관리학회논문집
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• 제22권5호
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• pp.86-98
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• 2021

본 연구에서는 PC (Precast Concrete) 공법 기반 건설공사에 대한 공급사슬 관리를 위한 시뮬레이션 모형을 개발한다. 이를 위해, 문헌과 현장 조사를 통해 공장 제작/현장 시공 체계에 대한 자료를 수집하고, 이를 바탕으로 공급사슬, 개체, 자원, 공정 등을 서술함으로써 시뮬레이션 모형을 정의하였다. 이어서, Arena 시뮬레이션 소프트웨어를 이용하여 데이터 모듈, 플로차트 모듈, 애니메이션 모듈을 작성함으로써 PC 공급사슬 시뮬레이션 모형을 개발하였다. 마지막으로, 개발된 모형의 논리성 검증과 유효성 확인을 위한 모형검토, 애니메이션 검토, 극한치 검증, 평균치 검증, 실제 사례 검증 등의 방법론을 이용하여 모형의 타당성을 검토하였다. 검토 결과, 개발된 시뮬레이션 모형은 논리적 오류 없이 PC 공급사슬의 공정과 특성을 적합하게 표현하고 있었으며, 더불어 대상 공급사슬에 대한 정확한 성능평가 예측치를 제공하는 것으로 나타났다. 향후, 본 연구에서 개발된 시뮬레이션 모형은 PC 공급사슬 체계를 최적 운영하기 위한 관리 기법을 개발함에 있어 성능 평가를 위한 플랫폼으로서의 역할을 충실히 수행할 수 있을 것으로 기대된다.

• 대한산업공학회지
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• 제20권4호
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• pp.181-192
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• 1994

In an order-oriented production system such as mold manufacturing, the production starts with an order acceptance, and the production planning is set up according to the accepted order information. Such a work can be done through a dynamic process management system which can reflect shop floor situation dynamically. In this paper, so called the Quick order acceptance evaluation system that can investigate order confirmation quickly, is discussed. When an order is asked, this system must consider the time constraint to determine whether to accept or not, and must be reliable when the determined results are used in the shop floor. For this system, firstly, we simplified the machines by grouping based on their operation capabilities, secondly, we conducted load analysis to calculate available capacities during given periods using heuristic method instead of mathematical algorithm, thirdly, expert can input his experienced knowledge into the system interactively when simulation results don't meet the required due dates. As a case study, we applied this system to an injection mold manufacturing factory.

• 해양환경안전학회지
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• 제23권4호
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• pp.421-431
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• 2017

본 연구에서는 기존에 제안되었던 공정 중심 모델링 방법을 개선하여 조선소의 다양한 생산 정보와 제약조건을 효과적으로 표현할 수 있도록 개선된 공정 중심 시뮬레이션 모델링 방법을 제안하였다. 그리고 이를 이용하여 시뮬레이션 모델을 구축할 수 있도록 다이어그램 구성 요소와 모델링 방법을 상세히 기술하였다. 이 모델링 방법에서는 복수의 제품과 설비가 공정에 투입되었을 때 우선순위를 지정할 수 있으며, 계층 구조를 가진 시뮬레이션 모델을 표현할 수 있도록 레이어 개념이 적용되어 있다. 그리고 조선소 생산 계획 정보를 바탕으로 절단 공정부터 대조립 블록 조립 공정까지를 본 논문에서 제안하는 방법으로 모델링하다. 이를 통하여 본 논문에서 제안하는 방법이 단일 설비가 여러 용도로 사용되는 경우에 기존의 모델링 방법에 비하여 유리한 것을 확인하였다. 결과적으로, 개선된 공정 중심 시뮬레이션 모델링 방법은 기존의 공정 중심 시뮬레이션 모델링 방법에서 표현하기 힘들었던 제약 조건과 흐름을 효과적으로 표현할 수 있으며, 계층 구조를 가진 조선소 생산 계획 검증 시뮬레이션 모델을 체계적으로 구축하는데 활용할 수 있다.

• 품질경영학회지
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• 제45권4호
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• pp.829-846
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• 2017

Purpose: This paper compares the effectiveness of typical selective assembly criteria and suggests the most promising one. Based on the result of a computer simulation, the key issues of selective assembly are examined and the best criterion is recommended from the effectiveness perspective. Methods: Using JAVA program, production of ten thousand units for each pair of components are simulated for selective assembly of the two types. And the number of mismatching and the fraction nonconforming for each criterion are determined. Results: The best match criterion appeared to be most promising from the perspectives of both mismatching and nonconforming problems. Its effectiveness appears to be also good even when the precision of one component is different from that of the other. Conclusion: For designing an optimal method for selective assembly, the best match criterion is recommendable as the base criterion.

• 한국시뮬레이션학회논문지
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• 제12권4호
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• pp.1-15
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• 2003

To satisfy and respond quickly to customers' demand, many companies are now aggressively focusing on supply chain management in order to strengthen their competitiveness. The modeling and analysis of supply chain environment have been widely studied. This study is concerned with the development of supply chain simulator which deals with stochastic natures existing in the supply chain environment. We proposed the mathematical model for the efficient cost analysis and developed the supply chain simulator based on the proposed mathematical model with object-oriented language C++. The simple experiment which find the best combination of policies considering the whole cost shows the possibility and reasonability of the developed simulator.