• 한국정밀공학회지
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• 제15권6호
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• pp.90-96
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• 1998

Helical gear system is widely used to transmit heavy duty power with harmonies and silences between parallel shafts. This paper predicts a life with Weibull distribution and estimates a reliability based on recycle principle of helical gear systems. 2-parameter Weibull distribution is generally adopted to estimate the mechanical life and the reliability of most gear systems, because this Weibull distribution is proper to explain a characteristics or a life of parts of gear systems with linearity of probability density data on weibull data sheet. For a high reliability, this paper estimates a number of overhaul times and a number of needed substitutes (exchange attachment,1 or parts) with following renewal theory, One is make an exchange of whole module include failure attachments/parts and second estimating method is only exchange of a failure attachments / parts.

• Corrosion Science and Technology
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• 제12권3호
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• pp.142-148
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• 2013

Safety is a major concern in Nuclear Power Plants (NPPs). Piping systems in NPPs are very complex and composed of many components such as tees, elbows, expanders and straight pipes. The high pressure and high temperature water flows inside piping components. As high speed water flows inside piping, the pipe wall thinning occurs in various reasons such as FAC (Flow Accelerated Corrosion), LDIE (Liquid Droplet Impingement Erosion) and Flashing. To inspect the wall thinning phenomenon and protect the piping from damages, piping components are checked by UT measurement in every overhaul. During every overhaul, approximately 200~300 components (40,000~60,000 UT data) are examined in NPPs. There are some methods from EPRI for evaluating wear rate of components. However, only few studies have been conducted to find out the raw data reliability for the wear rate evaluation. Securing the reliable raw data is the key factor for a reasonable evaluation. This paper suggests the reliability analysis method for the repeatedly measured data for wear rate evaluation.

• 항공우주
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• 통권104호
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• pp.20-23
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• 2009

지난해 11월, 국내 항공산업 발전방안을 주제로 한 공청회에서 민수부분 신규 성장동력으로 MRO(Maintenance, Repair and Overhaul) 산업 활성화가 이슈로 떠올랐다. 이에 본지는 현재 성장하고 있는 전 세계 MRO 시장을 전망하고, 국내 MRO 현황을 조망해 본다.

• Tribology and Lubricants
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• 제32권3호
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• pp.82-87
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• 2016

We performed an experimental research on lubricant oil in dual fuel medium-speed engines. It is important to select the appropriate lubricant oil because it could significantly affect engine lifetime and performance. We generally recommend the selection of the lubricant oil according to the fuel grades as contents in the project guide. However, it is a considerable challenge for shipyards to implement this concept because of the lack of space to install the complicated lubricating oil system for dual fuel engines. Therefore, we determine the adaptability of one-common lubricant oil for HiMSEN dual fuel engine through this experimental research. To check abnormality in gas mode operation and durability of engine components when a lubricating oil with high BN (base number) is used, overhaul inspections and lubricant oil analysis are carried out two times, and four times, respectively, during an operation of approximately 300 h. We investigated the variations in kinematic viscosity, base number, element quantity, pentane insoluble and sulfated ash in lubricant oil analysis. Moreover, we also investigated whether the deposit formation or wear occurred in various bearings, injectors, exhaust valves, intake valves, piston rings and so on through the overhaul inspections. There are no problems in the lubricant analysis and the overhaul inspections. Through the experimental research, we confirm that one-common lubricant oil should be selected according to the higher sulfur content of fuel oil in dual fuel engines.

• 국방과기술
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• 10호통권128호
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• pp.34-41
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• 1989

프랑스가 제안하는 효율적인 기술이전계획은 점진적인 과정이다. 시작단계에서는 프랑스에서 제공하는 잠수함의 정비유지에만 제한 적용되며, 정비 엔지니어와 기술자들이 계획된 방법으로 잠수함의 개념과 기술에 관한 지식을 획득할수 있을 것이다. 목표는 현지 조선소가 잠수함의 창정비(overhaul)를 능숙히 수행할 수 있도록 하는 것이다. 또한 기술이전은 자국내 잠수함 건조의 경우 3단계에 걸쳐 수행된다(p.39 참조)

• 한국안전학회지
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• 제32권3호
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• pp.34-40
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• 2017

The catastrophic collapse of the in-boiler scaffolding system in the two thermal power plants occurred in March and April 2012. After site investigation and document review, it was found that the specialized scaffolding system was imported for overhaul & maintenance and that the system did not get the safety certification at the import. In this regard, this study developed & proposed an access platform and a support for the vertical tube section of the super heat as well as a variable-length platform for the horizontal tube section, satisfying the domestic certification standards. The access platform was developed to be easy to handle by the worker with a weight of about 0.069 kN, which could reduce the risk of falling accidents and workers' musculoskeletal diseases. For the variable-length platform, it is possible to cope with various changes in length between the horizontal tubes associated with the increase of rigidity in the overlapping and the elimination of the protrusion.

• 한국철도학회논문집
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• 제10권2호
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• pp.231-242
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• 2007

As railroad industry faces the new Renaissance era, effective and efficient maintenance methods for rolling stock operation are required with advanced railroad technology. All kinds of railroad systems such as high-speed long-distance train, metropolitan mass transit and light rail require systematic maintenance technology in order to maintain the safe railroad operation. Simulation models for regular operations of the example maintenance center are developed. In this study, standard maintenance procedures, layout, equipments, and number of workers of Siheung Metropolitan Railroad Maintenance Rolling Stock Depot are considered. The proposed simulation models are developed using simulation package ARENA. After simulation, four types of observations are analyzed. First, the bottleneck operation is identified. Second, the relationship between maintenance center size, number of workers and cycle time is analyzed. Third, the scheduling performances between PERT/CPM and Critical Chain Project Management(CCPM) are compared. Lastly, the simulation results according to worker's working coverage shows expanding the worker's coverage decreases the cycle time and increases throughput per train. However, workers are to be fully trained to do multiple skill work.

• 항공우주정책ㆍ법학회지
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• 제29권2호
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• pp.163-181
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• 2014

MRO(Maintenance, Repair and Overhaul) 산업은 세계항공시장의 성장과 함께 발전하고 있다. 특히, 중국의 항공시장을 고려할 경우 아시아 지역의 MRO 산업은 상당한 성장 잠재력을 보유하고 있다. 아시아 지역에서 싱가포르는 한국보다 앞서 MRO 산업을 성공적으로 발전시킨 국가이며 그 중심에는 A*STAR가 있다. 본 논문은 MRO 산업의 성공적인 사례라 할 수 있는 싱가포르 A*STAR를 중심으로 분석하고 항공안전기술 전문기관을 통한 국내 항공산업과 항공분야 연구개발의 발전 방안을 제시하고자 한다.

• 한국철도학회논문집
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• 제11권3호
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• pp.240-247
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• 2008

최근 들어 각 철도 운영기관들은 유지보수 정보 시스템을 구축하여 고장 및 유지보수 데이터를 수집하고 있다. 그 한 예로서 서울특별시도시철도공사(SMRT)에서는 전동차정보시스템(EMU-IS) 을 국내 최초로 개발하여 2000년 8월부터 본격적으로 사용을 시작하였다. 본 논문에서는 SMRT 전동차량 운영으로 EMU-IS에 모아진 운행, 정비, 고장 데이터를 분석하여 신뢰도를 평가하고 유지보수주기를 결정하는 사례를 다루었다. 그 사례로서 도어시스템의 주요 아이템에 대해 신뢰성을 시간 빛 거리 기준으로 평가하고 오버홀 주기를 결정하는 문제를 다루었다.

• 항공우주시스템공학회지
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• 제8권3호
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• pp.34-40
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• 2014

Since the global economic crisis in year 2008, the world civil helicopter market has been growing recently. According to the market outlook in the next decade, the demand of civil helicopter will be driven by the demand of Private & Corporate, Oil & Gas, Off-shore and EMS(Emergency Medical Service) usages. On the other side, the demand of military market will be driven by the modification and upgrading for life extension or performance enhancement than the new helicopter development for replacing old models. To summarize these situations, the demand of MRO(Maintenance, Repair & Overhaul) market has also been on the rise because of the demand due to above several usages in civil side and the life-extension in military side. Through the MRO market analysis for characteristics, developmental trends and a supply chain, this paper describes that the potential of MRO business is considerably large as a propulsive power of domestic helicopter industry. And also, it proposes the construction direction of MRO network because the domestic industry must make the developmental awareness and reliability a stepping-stone towards own helicopter.