• Journal of Advanced Marine Engineering and Technology
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• 제23권6호
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• pp.785-793
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• 1999

There are two kinds of method in ship maintenance. One is the corrective maintenance and the other is the preventive maintenance. For these maintenances recently the stochastic techniques are widely used to keep the maximum availibility and the optimal maintenance period minimizing a given cost function. Thus this paper suggest a method to decide the optimal policy of ship's maintenances by using dynamic programming and the effectiveness of the method is verified through several examples in which failure rates and maintenance data of ship's machineries and parts are given.

• 환경영향평가
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• 제23권3호
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• pp.208-219
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• 2014

This work aims to establish the landscape ecological countermeasures to improve the sustainability of urban mountain forest and to enrich the biodiversity in twenty mountains of the Seoul Metropolitan City. Landscape ecological analysis was conducted based upon various criteria, such as area and elevation of mountains, flora, naturalized plants, vegetation, forest types, mountain trails, and public facilities. Various measures were suggested for the better maintenances of floristic diversity, introduced plants, vegetation and forest types of urban mountain forests. Sustainable recommendations for land use adminstration were developed for the preparations of a climate change-adapted urban mountain forests, as well as rational managements of ecosystem, walking trails, and public facilities within mountain forest. Rich and diverse natural vegetation as well as high floristic diversity were reported at mountains with higher elevations, larger area size, and rich landscape diversity. Mountains with low elevation, small size with easy public access, however, might require an urgent action to decrease the burdens by anthropogenic disturbances and urban development.

• 산업공학
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• 제14권1호
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• pp.47-53
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• 2001

This paper was studied to present a model for the application of AHP to the selection of airliners. For this study, a questionnaire was developed in respect to the criteria of airliner and given to 80 airline pilots and 30 maintenances in airlines to ask their opinions about the candidates for the middle-range airliners. The AHP software developed by Korean Advanced Institute of Science Technology (KAIST) was used to process the data. The result was analyzed by the criteria of selecting airliners and the several alternatives for the middle-range airliners.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.231-234
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• 2000

This paper was studied to present a model for the application of AHP to the selection of airliners. For this study, a questionnaire was developed in respect to the criteria of airliner and given to 80 airline pilots and 30 maintenances in airlines to ask their opinions about the candidates for the middle-range airliners. The AHP software developed by Korean Advanced Institute of Science Technology (KAIST) was used to process the data. The result was analyzed by the criteria of selecting airliners and the several alternatives for the middle-range airliners.

• Journal of Advanced Marine Engineering and Technology
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• 제35권6호
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• pp.849-855
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• 2011

구명정은 선박이 좌초나 침몰 시 인명구조용으로 구조는 황천시 물이 구명정내부로 들어오지 못하도록 밀폐형으로 되어 있다. 밀폐형 구조로 인해 구명정내부는 온도가 상승되고 이 온도 상승으로 인해 엔진시동용 배터리가 폭발 가능성이 있고, 실제로 목포해대 실습선의 구명정에 탑재된 배터리에서 폭발사고가 발생했다. 폭발에 대한 원인조사를 바탕으로 폭발방지를 위한 대안 연구를 수행하였다. 본 연구에서는 발생된 사고의 방지를 위한 구명정의 구조개선, 충전장치, 법규개정을 위한 기초적 자료를 제안하였다.

• 전기학회논문지P
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• 제67권2호
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• pp.70-74
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• 2018

Social infrastructure such as production, transportation, gas, and electrical facilities would be degraded according to time and those facilities might need more maintenances, repairing, and management as time goes by. Especially, in the case of a power transformer, it is important to diagnose the transformer in order to avoid malfunction and failure because they could cause enormous damage. The economic as well as technical aspects of a transformer management must be considered while it is operated. Therefore, the concept of asset management should be applied as an advanced method of transformer management. Asset management refers to a series of processes to make a plan of maintenance and conservation of a power transformer considering the soundness, investment cost, and importance of equipment. It is important to apply the asset management considering calculation of a lifetime loss. In this paper, the lifetime loss calculation method of asset management for a power transformer is suggested.

• 산업경영시스템학회지
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• 제40권1호
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• pp.57-64
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• 2017

In order to reduce damages to major railroad components, which have the potential to cause interruptions to railroad services and safety accidents and to generate unnecessary maintenance costs, the development of rolling stock maintenance technology is switching from preventive maintenance based on the inspection period to predictive maintenance technology, led by advanced countries. Furthermore, to enhance trust in accordance with the speedup of system and reduce maintenances cost simultaneously, the demand for fault diagnosis and prognostic health management technology is increasing. The objective of this paper is to propose a highly reliable learning model using various machine learning algorithms that can be applied to critical rolling stock components. This paper presents a model for railway rolling stock component fault diagnosis and conducts a mechanical failure diagnosis of motor components by applying the machine learning technique in order to ensure efficient maintenance support along with a data preprocessing plan for component fault diagnosis. This paper first defines a failure diagnosis model for rolling stock components. Function-based algorithms ANFIS and SMO were used as machine learning techniques for generating the failure diagnosis model. Two tree-based algorithms, RadomForest and CART, were also employed. In order to evaluate the performance of the algorithms to be used for diagnosing failures in motors as a critical railroad component, an experiment was carried out on 2 data sets with different classes (includes 6 classes and 3 class levels). According to the results of the experiment, the random forest algorithm, a tree-based machine learning technique, showed the best performance.

• Journal of Advanced Marine Engineering and Technology
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• 제20권3호
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• pp.19-28
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• 1996

In Asia countries the productions of ship building and marine engines have been increasing, specially Japanese marine industries have worked hard after 1960s and Korean ones after 1980s. Recently the other countries, as Taiwan and China, have been working so that these hour Asian countries are occuping the high level of shared ratio of productions for gross tonnages and horse powers, which are 74 and 64[%] of the world ones ($8.6\times10$+6[GT], $8.6\times10$+6[PS]) in 1994. Korean industries had the highest shared ratio of production of tanker vessel and 2 stroke diesel engine as 45[%]($2.2\times10$+6[GT]) and 37[%]($1.0\times10$+6[PS]) which were more than those of Japan as 34 and 16[%] in 1989 respectively. Some marine databases and their network links among Asian countries are proposed due to the posibility of collection and analyses with their own specifications by the marine industries and operators as well as Japanese ship reliability investigation works(SRIW) like SRIC in Japan. During 1966 and 1996 16 times of SRIW in Japan have been carried out by ship reliability investigation group(SRIG) in Japan. There have been collected and evaluated a great number of field data of failures and maintenances($700\times10$+3[occ], $1.6\times10$+6[MH}) during running hours($13.4\times10$+6[Hrs]), from which many kinds of evaluation indices could be gotten as the three indices of occurring rate$\lambda$(52.2[occ/1000Hrs]), average man-hour mh(2.29[MH/occ]) and manning index MI(119[MH/1000Hrs]). An estimation example having the three indices$\lambda$, mh and MI were shown by the SRIC 1990 Data Base in Japan for the two kinds of fuel oil suppling subsystems which are dual fuel oil one(DFOS) and mono fuel oil one(MFOS). Three indices MI, and mh for DFOS and MFOS results in 7.16 and 5.20[MH/1000Hrs], 2.63 and 2.06[occ/1000 Hrs]. Therefore the more simple subsystem MFOS can save approximately 30[%] of maintenance load. Finlly an utilization methods are shown for the SRIC in Japan by means of computer system and worlwide internet links.