• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.169.5-169
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• 2001

This study proposes a neural network for solving optimization problems such as the TSP (Travelling Salesman Problem), scheduling, and line balancing. The Hopfield network has been used for solving such problems, but it frequently gives abnormal solutions or non-optimal ones. Moreover, the Hopfield network takes much time especially in solving large size problems. To overcome such disadvantages, this study adopts nodes whose outputs changes with a fixed value at every evolution. The proposed network is applied to solving a TSP, finding the shortest path for visiting all the cities, each of which is visted only once. Here, the travelling path is reflected to the energy function of the network. The proposed network evolves to globally minimize the energy function, and a ...

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1996년도 추계학술대회발표논문집; 고려대학교, 서울; 26 Oct. 1996
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• pp.275-278
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• 1996

We propose dynamic file allocation method in distributed database management system with changing access patterns. There are a lot of studies on file allocation problem in D-DBMS, and those studies deal with off-line analysis and optimization. Those works are well for systems with static database access patterns, but are inadequate for systems that have changing access patterns. In these systems, dynamic file allocation along with access pattern is more proper. In advance, Brunstrom et al. studied on this area, but they dealt a extremely simplified model. So, we make more practical models to simulate real system. In these models, many factors that were disregard in the advance study are considered. These models are composed with the non-replication system and the replication system. In addition to, we deal with CPU workload balancing in such system in order to improve performance of systems. Our methodology is very simple and realistic, therefore we think that it will give a lot of improvement in D-DBMS with changing access pattern.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.148-152
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• 2006

제품(또는 서비스)을 생산하기 위하여 여러 순차적인 작업이 수행되어야 하는 환경에서 생산자원(기계 또는 작업자)에게 얼마만큼의 요소작업을 배정하는가를 결정하는 작업배정(Work Assignment) 문제는 중요한 의사결정 문제이다. 일반적으로 이용하는 작업배정 방식은 각 생산자원에게 가급적 균등한 작업량을 배정하는 라인밸런싱(LB: Line Balancing) 전략이다. 그러나 LB 방식은 작업자의 작업속도 차이나 시스템의 여러 가지 변동 상황(기계고장, 품질문제 등)의 고려 없이 작업을 배정하기 때문에 실제로는 계획된 밸런싱효율을 달성하기 어렵다. Bucket Brigade (BB)는 이러한 문제에 대응하기 위한 새로운 작업배정 방법으로 제시되고 있다. BB는 개미의 협력작업 개념을 바탕으로 하는 분산 자율적인 작업배정 방법이다. 본 발표에서는 생산 및 물류시스템에서 BB의 적용 가능성과 문제점을 논의하고, 시뮬레이션을 통하여 여러 작업 환경에서 BB의 수행도를 분석한다.

• 한국생산제조학회지
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• 제20권5호
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• pp.659-665
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• 2011

Recently, the plastic resin such as PC, ABS are widely used in IT market. Especially, in most cases the keypads mounted on the mobile phone are the dual-injection-plated type. Environmental regulation is based on the quality of injection-molded products and the minimum process steps are required to avoid the plating defects. Various parameters to produce the injection-molded plastic products make it difficult to obtain the desired stability. However, the past experience and the use of CAE analysis make it possible to predict the problems occurred in injection molding process. Especially, the problems of the weld lines such as runner balancing, bending, deformation and forming defects can be solved systematically and minimized by CAE analysis. Through this study, the non-uniform volumetric shrinkage and the difference in temperature distribution induce the deformation and the high value of stress causes the problems such as crack.

• 설비공학논문집
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• 제20권3호
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• pp.175-180
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• 2008

Flow quantity to supply to a coil in floor heating system is important to achieve comfortable indoor air condition in the winter season. The hot water header is used to distribute the water into the coil. Experimental study has been performed using the water header that have 5 branches consisted of flow control valves and automatic shut-off valves. Each branch line connected it with X-L pipe. Experimental tests accomplished it to investigate the flow distribution characteristics of the hot water header. Experimental results show that the selection of the pump head and differential pressure are very important to save running energy of the system, and high differential pressure needs more friction loss in the case of suitable differential pressure for balancing of the header.

• 산업공학
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• 제21권3호
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• pp.333-342
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• 2008

Warehouses form an important link in a supply chain network. Among a variety of activities in warehouses, order picking is the process of retrieving a number of items out of storage to meet customer orders. Today, as the transactions through direct sales are wide spread, warehouses often receive a large amount of small orders to be handled within tight time windows, which makes fast and efficient order picking more important than ever. This paper examines a new order picking method where the concept of bucket brigade (BB) is applied. Bucket brigade is a way of dynamically coordinating workers who progressively perform a set of operations along a flow line. In bucket brigades, a worker is not assigned his jobs in a static way. Each worker takes a job from his predecessor when he is free. We identify some considerations when bucket brigades are applied to order picking activities. A new BB picking protocol is presented to improve existing BB picking protocols. Through simulation experiments, the performance of BB order picking is evaluated under various logistics environments.

• 대한기계학회논문집B
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• 제33권11호
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• pp.886-893
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• 2009

To develop glass panel vacuum lift system for the post process in module line of FPD(Flat panel display) such as LCD and PDP, new vacuum adsorption parts of this system are proposed. These parts are composed of variable geometry configurations utilizing ceramic porous medium for variable size of glass panels. In order to design this device, detail understanding of flow phenomena in the flow path of vacuum adsorption system is essential. Thus, CFD analysis and designs are performed for several configurations in terms of pressure drop and balancing force at the adsorption side. From the result, new configuration is recommended for optimum design and manufacturing purpose.

• 품질경영학회지
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• 제19권1호
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• pp.141-150
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• 1991

This paper is aimed to construct a CIM(Computer Intergrated Manufacturing) model through optimal flexible manufacturing systems for factory automation in order to provide higher productivity. This paper provides a ease through an analytical method to construct flexible manufacturing systems for factory automation. The contents of this paper include forecasting of demands which analyze variation of demand using Winter's model, line balancing utilizing Lanked Positional Weight Method, and a case analysis through simulation by Monte Carlor Method. The result shows the manpower and net present value of investment have decreased 42% and 19.6%, respectively, and yearly net profit has increased 30%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3171-3191
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• 2016

Due to growing demand on wireless data traffic, a large number of different types of base stations (BSs) have been installed. However, space-time dependent wireless data traffic densities can result in a significant number of idle BSs, which implies the waste of power resources. To deal with this problem, we propose an active state control algorithm based on semi-Markov decision process (SMDP) for a heterogeneous network. A MDP in discrete time domain is formulated from continuous domain with some approximation. Suboptimal on-line learning algorithm with a random policy is proposed to solve the problem. We explicitly include coverage constraint so that active cells can provide the same signal to noise ratio (SNR) coverage with a targeted outage rate. Simulation results verify that the proposed algorithm properly controls the active state depending on traffic densities without increasing the number of handovers excessively while providing average user perceived rate (UPR) in a more power efficient way than a conventional algorithm.

• 아태비즈니스연구
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• 제5권2호
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• pp.1-12
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• 2014

Tourism has been considered as the largest industry in the world, which is contributing towards employment generation, wealth creation and pursuing social benefits. Growing concern about the impact of human activities upon the environment, increased awareness of and concern for global environment have intensified the demand for sustainable tourism and their focus on balancing of: profit-driven motives, preserving and enhancing the social as well as ecological balance. Based on secondary materials and content analysis present study evaluated existing status of sustainable tourism development and explored important change strategies for future improvement of tourism sector in Bangladesh. The study recognized different views of change management and various strategies for obtaining sustainability in tourism industry. The present study identified the institutional networks, challenges in the way of applying systems approach to change management for sustainable tourism development and suggested important options for overcoming the impediments to operate through the proposed strategic framework in Bangladesh.