• 한국신뢰성학회지:신뢰성응용연구
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• 제16권3호
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• pp.257-262
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• 2016

Recently, the subject of reliability attracts a great deal of domestic and international attentions and the extensive research activities are being conducted as well. Such trend exists mainly due to the fact that the research on the subject of reliability not only contributes to the theoretical developments, but also may find a wide range of applications in practice over several fields. In particular, the research regarding the maintenance policy incorporating certain types of warranty for repairable system and its application is being performed extensively by many researchers, and their efforts seem more concentrated on developing new maintenance policies which minimize the expected operating cost incurred for replacement and repair of the system, while keeping the system at high reliability. Effective maintenance policy may reduce the operating cost and decrease the downtime of the system during its mission period and consequently, increase the productivity of the system. In this article, the major areas of interest in the field of reliability and its historic perspectives are given briefly and the theoretical aspects in several fields of reliability including the maintenance and warranty policies is also discussed. Furthermore, the current domestic situation regarding the education and research on reliability is presented, along with the importance of reliability theory and the difficulty of training reliability personnel. Finally, the author's opinion for effective education system is proposed.

• 한국조리학회지
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• 제12권3호
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• pp.17-31
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• 2006

There have not been the best method for improving the management system of an enterprise. Its management system must be changed according to new environment. Therefore, the food service industry had to accept outsourcing strategies to reduce cost and construct the core-capability of enterprise. In this respect, we studied the introduction and the satisfaction in outsourcing strategies for family restaurants, including a post of enterprise, decision on the supply-enterprises, contract preparation, cost of outsourcing, recontract items and outsourcing result estimation. The results of this study were as follows; First, 90.5% of managers for 7 family restaurants felt that outsourcing is needed. Second, the post of the outsourcing for 7 family restaurants was from 1 to 8; supply for raw food material, cleaning and equipment repair. The introduction of outsourcing for 7 family restaurants started in 1995 and it had constantly made progress up to 2003. Thirdly, the advantages of the outsourcing for 7 family restaurants were increase of benefit, improvement of controllable-power for family restaurants and improvement of employees' satisfaction. Fourthly, 42.9% of managers were satisfied and 4.8% of them were not satisfied. 36 to 40 year old vice-managers were very satisfied with the result of the outsourcing. Fifth, 90.5% of family restaurant managers found the outsourcing to be needed and especially managers in their late thirties realized the outsourcing.

• 대한안전경영과학회지
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• 제7권1호
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• pp.101-115
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• 2005

This study deals with the procedure of safety improvement, productivity increase ,and tact-time reduction through setting up the system about preventive maintenance. Actually, it is hard to establish and carry out preventive maintenance, even though we recognize the importance of the system concerning time, cost, labor, and so forth. In this study in the viewpoint of cost we are for achieving maximum efficiency by change and reduction of planning process adapted to the special work group. At first we briefly will mention the kind ,the necessity ,and the concept of preventive maintenance ,and then divide the equipment used in the assembly line into the two whether it is necessary or not by way of estimating the breakdown loss ,comparing with general establishment of preventive maintenance and modifying it to the case. At the second step we will establish the operation system of plan management related to production and quality in the special case. Check period and category will be set by dividing the assembly equipment into LCL and Focus in the third step. The forth step will contain the operation procedure in detail. And then we must make check and repair record periodically. Finally, on the basis of the record the selection of checking of significance will be conducted. This results in safety improvement, tact time reduction, and productivity improvement.

• 농촌지도와개발
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• 제25권3호
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• pp.149-160
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• 2018

This study aimed to analyze the replacement investment of the diesel fuel system with the pallet fuel system in the Korean farming sector. Equivalent annual annuity approach was used to resolve a discrepancy of useful life in capital goods and to facilitate investment analyses in an independent perspective. Data was obtained from previous studies on economic analysis of greenhouse tomato, paprika and cucumber. Results showed that the replacement with the pallet fuel system was acceptable irrespective of the remaining period of useful life for the diesel fuel system. In addition, sensitivity analysis with government support level, repair cost, and light and heat energy cost show ed robustness in the possibility of replacement with the pallet fuel system while the speed of replacement was accelerated with an increase in the amount of diesel fuel used and price of diesel fuel, and a decrease in price of the pallet fuel. The result implied that the replacement investment rather than a new investment was appropriate for existing greenhouse farmers and the pallet fuel system was acceptable to replace existing diesel fuel system in producing greenhouse tomato, paprika and cucumber.

• 한국군사과학기술학회지
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• 제14권3호
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• pp.414-422
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• 2011

In this paper, we analyze the standards of the bolts for maintaining the products. The maintainer don't know the detail information of bolts by seeing the shape of bolts when they repair the products. So they waste much time and cost. To solve the these problem, we propose the new systematical discrimination of bolts. To propose the discrimination code, we divide the shapes of the bolts into four classes(head, internal drive, shank and end). User can fine preferentially similar standards by just the shapes of bolts under the this discrimination code. And, User can find the standards of bolts that they want by using the additional information such as measurements. We will reduce the cost and time for the maintaining the products by using the proposed discrimination code.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 추계학술대회
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• pp.131-141
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• 2004

This study deals with the procedure of safety improvement, productivity increase, and tact-time reduction through setting up the system about preventive maintenance. Actually, it is hard to establish and carry out preventive maintenance, even though we recognize the importance of the system concerning time, cost, labor, and so forth. In this study in the viewpoint of cost we are for achieving maximum efficiency by change and reduction of planning process adapted to the special work group. At first we briefly will mention the kind, the necessity, and the concept of preventive maintenance, and then divide the equipment used in the assembly line into the two whether it is necessary or not by way of estimating the breakdown loss, comparing with general establishment of preventive maintenance and modifying it to the case. At the second step we will establish the operation system of plan management related to production and quality in the special case. Check period and category will be set by dividing the assembly equipment into LCL and Focus in the third step. The forth step will contain the operation procedure in detail. And then we must make check and repair record periodically. Finally, on the basis of the record the selection of checking of significance will be conducted. This results in safety improvement, tact time reduction, and productivity improvement.

• 산업공학
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• 제22권2호
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• pp.153-164
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• 2009

An effective management for reverse flows of products such as reuse, repair and disposal, has become an important issue for every aspect of business. In this paper, we study the Location-Routing Problem (LRP) in the multi-stage closed-loop supply chain network. The closed-loop supply chain in this study integrated both forward and reverse flows. In forward flow, a factory, Distribution Center (DC) and retailer are considered as usual. Additionally in reverse flow, we consider the Central Returns collection Center (CRC) and disposal facility. We propose a mixed integer programming model for the design of closed-loop supply chain integrating both forward and reverse flows. Since the LRP belongs to an NP-hard problem, we suggest a heuristic algorithm based on genetic algorithm. For some test problems, we found the optimal locations and routes by changing the numbers of retailers and facility candidates. Furthermore, we compare the efficiencies between open-loop and closed-loop supply chain networks. The results show that the closed-loop design is better than the open one in respect to the total routing distance and cost. This phenomenon enlarges the cut down effect on cost as an experimental space become larger.

• 한국군사과학기술학회지
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• 제2권2호
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• pp.166-172
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• 1999

Weapon system is defined as a combination of primary system and logistics support system which are evaluated by capability and operational availability respectively. Weapon system developer thought that primary system was weapon system and also only primary system was important. Recent comparison of total life cycle cost showed that logistics support system was proved to be more important than primary system. However, until now no systematic approach to logistics support system development have applied in the area of developing support system and much money was exhausted by wrong logistics support system. We need to construct a universal metric for effectiveness of logistics support system and to cut out whatever activities or support elements which do not contribute to the metrics. This study describes a new approach under the name function approach to logistics support system development and also classifies five factors of failure frequency, stock out of frequency, administrative delay time, active repair time and logistic delay time that have influence on operational availability of logistics support system.

• Smart Structures and Systems
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• 제30권6호
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• pp.571-582
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• 2022

Optimal life-cycle management is a challenging issue for deteriorating regional bridges. Due to the complexity of regional bridge structural conditions and a large number of inspection and maintenance actions, decision-makers generally choose traditional passive management strategies. They are less efficiency and cost-effectiveness. This paper suggests a deep reinforcement learning framework employing double-deep Q-networks (DDQNs) to improve the life-cycle management of deteriorating regional bridges to tackle these problems. It could produce optimal maintenance plans considering restrictions to maximize maintenance cost-effectiveness to the greatest extent possible. DDQNs method could handle the problem of the overestimation of Q-values in the Nature DQNs. This study also identifies regional bridge deterioration characteristics and the consequence of scheduled maintenance from years of inspection data. To validate the proposed method, a case study containing hundreds of bridges is used to develop optimal life-cycle management strategies. The optimization solutions recommend fewer replacement actions and prefer preventative repair actions when bridges are damaged or are expected to be damaged. By employing the optimal life-cycle regional maintenance strategies, the conditions of bridges can be controlled to a good level. Compared to the nature DQNs, DDQNs offer an optimized scheme containing fewer low-condition bridges and a more costeffective life-cycle management plan.

• 산업경영시스템학회지
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• 제45권1호
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• pp.83-90
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• 2022

This study deals with replacement analysis of deteriorated equipment for improving productivity of production system. Frequent breakdown of the deteriorated equipment causes a situation that reduces productivity such as low product quality, process delay, and repair cost. However, the replacement of new equipment will be required a high initial investment cost, so it is important to analysis the economic feasibility. Therefore, we analyze the effect of the production system due to the aging effect of the equipment and the feasibility of equipment replacement based on the economic analysis. The process flow, working time, logistics movement, etc. are analyzed in order to build the simulation modeling for a ship and land switchboard production system. Using numerical examples, the economic feasibility analysis of equipment replacement through replacement of existing deteriorated equipment and additional arrangement of new facilities is performed.