• Journal of the Korea Safety Management & Science
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• v.3 no.3
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• pp.77-86
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• 2001

An operational strategy for inventory control on finished goods in the distribution system has been given attention to many enterprises and many studies regarding this field have been done and is also on-going currently. Many of these studies represented a large scale distribution network with a unified formulation by using defined symbols. These methods have provided the systematic approach of the distribution network but they are impossible to applying the reality system due to not considering the service rate of demand and treating the shortage of inventory. In order to overcome these unrealistic problems, the novel safety stock policy of responding to customers' inventory distribution network is suggested. this paper explores the transportation between Central Distribution Center(CDC) and Regional Distribution Center(RDC). Especially, the relation of transportation cost between CDC and RDC and cost of inventory control according to safety inventory with service level are emphasized. We could obtain the good results of this study by determining the optimal safety stock considering the various variables and constraints.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.4
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• pp.357-363
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• 2004

Earlier models of card vending machines have generally motion drives with high cost and large size. However, current trend in card vending machines requires low-cost, compact-sized and readily installable motion drives. This paper shows the operational principle of the motion drive of a card vending machine and then presents the performance test results of the motion drive with improved mechanisms proposed in the paper. The results show that the proposed mechanism is valid and improves the card dispensing performance. The proposed model in the paper is accepted and introduced in the actual production line.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.14-20
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• 2003

Supply chain is the link that moves products between suppliers, manufactures, wholesalers, distribution, retailers and ended consumers. Supply chain management(SCM) is a way to supervise the flow of products, materials and information as they move along the supply chain. In the recent years, Most of the companies are in a hurry the introduction of SCM to obtain international competitiveness. The goal of SCM is to optimize the supply chain, which can not only reduce inventories, but may also create a higher profit margin for finished goods by giving customers exactly what they want. There are four major decision areas (location, production, inventory, transportation) in supply chain management, and there are both strategic and operational elements in each of these decision areas. This paper is concerned with the integrated production planning problem including not only the production cost but also the transportation cost in supply chains, and an efficient algorithm using genetic algorithm and quickest path method is presented to solve the problem.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.23-33
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• 2007

The constraints of traditional fish drying in Bangladesh have been reviewed and an effective solar fish dryer was developed with the small-scale processors and fishermen using locally available cheaper materials in order to dry fish in coastal region. After successful field testing, new solar dryer was demonstrated within the community in 3 different locations of Cox's Bazar for several batches of operations in each location from late September to March and found very effective in terms of architectural suitability, operational feasibility, technical efficiency, out-put quality (good texture, colour, flavour and long storage time), user's acceptability, commercial viability and environmental adequacy. A simple cost-profit analysis was done with the community operated products, which indicates that the new solar fish dryers could be operated profitably in coastal regions where sun-light and air flows are abundant.

• Journal of Industrial Technology
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• v.19
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• pp.217-226
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• 1999

A single phase to three phase power converter with cost effective and simple structure is proposed. The converter consists of rectifier and inverter. The rectifier is composed of a half wave rectifier, a dc link capacitor, and a current limiting inductor, and the inverter is of only two switches with PWM control. For negative sequence operation the inverter output voltage leads the line input by $60^{\circ}$, and for positive sequence operation the inverter output voltage leads by $60^{\circ}$. We can see that positive sequence operation shows higher output voltage, slight harmonic distortion(2%), and better performances such as high efficiency and high power factor. A mathematical model for system analysis is provided, and specifications for selection and control scheme both for start-up and for steady state are analyzed. comparison and operational limits of positive and negative sequence operation are performed, and simulations and experiments are executed to verify the proposed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.2
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• pp.246-262
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• 2013

With increases in international oil prices, the proportion of fuel cost to the operational costs of a ship is currently increasing. To reduce fuel cost, a method for determining an economical route for a ship based on the acquisition of the sea state and the estimation of fuel consumption is proposed. The proposed method consists of three items. The first item is to acquire the sea state information in real time. The second item is to estimate the fuel consumption of a ship according to the sea state. The last item is to find an economical route for minimal fuel consumption based on the previous two items. To evaluate the applicability of the proposed method, it was applied to routing problems in various ocean areas. The result shows that the proposed method can yield economical ship routes that minimize fuel consumption. The results of this study can contribute to energy savings for environmentally friendly ships.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.11
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• pp.140-148
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• 1993

High Integration ratio of CMOS circuits incredily increases the test cost during the design and fabrication processes because of the FET fault(Stuck-on faults and Stuck-off faults) which are due to the operational characteristics of CMOS circuits. This paper proposes a test generation algorithm for an arbitrarily large CMOS circuit, which can unify the test steps during the design and fabrication procedure and be applied to both static and dynaic circuits. This algorithm uses the logic equations set for the subroutines resulted from arbitrarily dividing the full circuit hierarchically or horizontally. Also it involves a driving procedure from output stage to input stage, in which to drive a test set corresponding to a subcircuit, only the subcircuits connected to that to be driven are used as the driving resource. With this algorithm the test cost for the large circuit such as VLSI can be reduced very much.

• International Journal of Reliability and Applications
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• v.2 no.4
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• pp.269-280
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• 2001

The objective of this paper is to provide a model for effective implementation of costing RAM management in the design and procurement of production facility considering the system cost-performance trade-off. This research proposes a two-step approach of costing RAM design and test of system RAM for production facility. In Step 1, a static model is proposed to find an initial system configuration to meet the required performance based on system RAM and LCC and analyzes the trade-off relationships between various factors of RAM and LCC. In the second Step, we developed time and failure truncated models for system reliability test and analysis. For the computational purpose, we developed computer programs and have shown the sample results. By the sample test run, the proposed model has shown the possibilities to provide a good method to analyze system performance evaluation for both design and operational phase, This model can be applied to a wide variety of systems not only for costing RAM of the production facilities but also for the other kinds of equipment.

• ETRI Journal
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• v.32 no.4
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• pp.503-511
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• 2010

WiBro radio frequency (RF) repeater is used for solving the problem of partial shadow areas in the wireless communication field that uses time-division duplexing (TDD) mode. In this paper, a method to efficiently generate TDD signals for WiBro RF repeater is proposed and its digital circuit is implemented. A TDD signal is detected from RF signals transmitted/received to/from RF repeater and then inputted again into the RF repeater, so that it can operate normally. First, the envelope of downlink signals is detected and then clamped to extract the basic form of a TDD signal using an operational amplifier circuit. Next, the TDD signal is generated by restoring and filtering the shape which has been distorted by the wireless channel. The algorithm and system to acquire TDD signal are developed with a goal to have simple but powerful functions with as little cost as possible. The proposed method is implemented as an RF-digital integrated system and verified through the experiments under the same condition as actual WiBro service environment.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.312-317
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• 1998

Reliable maintenance scheduling of main equipments is a crucial problem in thermal power stations in order to skirt overall losses of power generation resulted from severe failures of the equipments. A reasonable method was proposed to determine the maintenance scheduling of whole pump system in thermal power stations in order to reduce the maintenance cost by keeping the present avail-ability of the pump system throughout the operation. The dimensional reduction method was used to solve problems encountered due to few data which involved many operational factors in failure rate of pumps. The problem of bandlimited nature of data with time was solved by extrapolating future failures from presently available actual data with an aid of Weibull distribution. The results of the analysis identified the most suitable maintenance intervals of each pump type accordingly and hence reduce the cost of unnecessary maintenance with an acceptable range in the overall system availability.