• International Journal of Precision Engineering and Manufacturing
• /
• 제8권3호
• /
• pp.50-53
• /
• 2007

Improving the reliability or long-term dependability of a system requires a different approach from the previous emphasis on short-term concerns. The purpose of this paper is to present a reliability evaluation method for an oil cooler intended for high-precision machining centers. The oil cooler system in question is a cooling device that minimizes the deformation caused from the heat generated by driving devices. This system is used for machine tools and semiconductor equipment. We predicted the reliability of the system based on the failure rate database and conducted the reliability test using a test-bed to evaluate the life of the oil cooler. The results provided an indication of the reliability of the system in terms of the failure rate and the MTBF of the oil cooler system and its components, as well as a distribution of the failure mode. These results will help increase the reliability of oil cooler systems. The evaluation method can also be used to determine the reliability of other machinery products.

• 한국철도학회논문집
• /
• 제9권5호
• /
• pp.601-605
• /
• 2006

Reliability of the Railway signaling system which is safety critical is determined by reliability of hardware and software. Reliability of hardware is easily predicted and demonstrated through lots of different studies and environmental tests, while that of software is estimated by the iterative test outcomes so estimates of reliability will depend on the inputs. Combinations of inputs to and outputs from the software may be mostly combinatoric and therefore all the combinations could not be tested. As a result, it has been more important to calculate reliability by means of a simpler method. This paper identifies the reliability prediction equation applicable to reliability prediction for railway signaling system software, and performs the simulation of onboard equipment of automatic train control for high speed train to review reliability prediction and validity.

• 한국군사과학기술학회지
• /
• 제21권5호
• /
• pp.607-613
• /
• 2018

Hydraulic systems are widely used in the field of defense, construction machinery, agricultural machinery, and general industries, due to various advantages such as quick response speed and precision control. The defense equipments such as light rescue vehicle is operated in very harsh environments, so hydraulic components used in defense equipment are required to have very high reliability. In particular, hydraulic piston pump is very important component in a hydraulic systems, so life prediction of pump is essential. Therefore, in this study, we analyze the potential failure and the main failure mode of the hydraulic piston pump for the light rescue vehicle through the FMEA analysis, and predict the life of the pump by the accelerated life test considering the usage conditions.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1636-1639
• /
• 2005

The process equipment and remote handling for the deep geological disposal of high-level radioactive waste(HLW) should be checked prior to the operation in view of reliability and operability. In this study, the concept of virtual environment workcell is implemented to analyze and define the feasible disposal process instead of real mock-up, which is very expensive and time consuming. To do this, the parts of process equipment for the disposal and maintenance will be modeled in 3-D graphics, assembled, and kinematics will be assigned. Also, the virtual workcell for the encapsulation and disposal process of spent fuel will be implemented in the graphical environment, which is the same as the real environment. This virtual workcell will have the several functions for verification such as analyses for the equipment's work space, the collision detection, the path planning and graphic simulation of the processes etc. This graphic virtual workcell of the HLW disposal process can be effectively used in designing of the processes for the hot cell equipment and enhance the reliability of the spent fuel management.

• 한국정보기술응용학회:학술대회논문집
• /
• 한국정보기술응용학회 2002년도 추계공동학술대회 정보환경 변화에 따른 신정보기술 패러다임
• /
• pp.199-204
• /
• 2002

보전에 중점을 둔 신뢰성(RCM)은 1960년대 후반 상업용 항공기산업을 위해 개발되었고, 현재는 항공기 이외의 여러 장치에도 적용되고 있다. RCM은 예방보전계획을 수립하기 위한 방법으로 예방보전계획은 장치와 구조물의 안전성과 가동성 수준을 효율적이고 효과적으로 성취하게 한다 RCM은 장치와 구조물에 적용가능하면서 효율적인 예방보전요구를 확인하기 위해 결정논리나무를 사용한다. 결정논리를 통하여 보전작업의 실행 필요성에 대하여 최종적으로 판단한다. 본 연구에서는 IEC 60300-3-11을 중심으로 기기나 장치에 대한 RCM분석방법 및 운용방법에 대한 지침을 제공하고자 한다.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제1권2호
• /
• pp.79-93
• /
• 2001

Recently, new aspects of paints such as a beautiful appearance, use of environmentally friendly paints, etc., in addition to the superior performance of paints have been requested for industrial paints including the paints for heavy construction equipment and others. Particularly, the quality of appearance of coating affects the sales of heavy construction equipment. And the necessity for the paints to have a superior weather-proof property without changing the luster or color even after long-time exposure to the open air is emphasized. The change in the surface color and luster of the paint due to the natural environment progresses very slowly, and it takes a long time to verify material properties when developing new paints. In order to improve such methods, weathering tests are performed in many laboratories as a test for accelerating aging of coating, and the lifetime of the products is estimated through evaluation of the weathering (environment-proof) quality of paints. However, not a great deal of research activity has been conducted up to the present time since the interrelationship between the actual results of testing and field data is different for each paint and it takes a long time to study relevant materials. Therefore, introduced in the present study is the estimation of the change in the quality of appearance of coating in the field through the accelerated aging test among the cases of improvement of the quality of appearance of the urethane paint for heavy construction equipment.

• 한국산업정보학회:학술대회논문집
• /
• 한국산업정보학회 2002년도 추계공동학술대회
• /
• pp.199-204
• /
• 2002

보전에 중점을 둔 신뢰성(RCM)은 1960년대 후반 상업용 항공기산업을 위해 개발되었고, 현재는 항공기 이외의 여러 장치에도 적용되고 있다. RCM은 예방보전계획을 수립하기 위한 방법으로 예방보전계획은 장치와 구조물의 안전성과 가동성 수준을 효율적이고 효과적으로 성취하게 한다. RCM은 장치와 구조물에 적용가능하면서 효율적인 예방보전요구를 확인하기 위해 결정논리나무를 사용한다. 결정논리를 통하여 보전작업의 실행 필요성에 대하여 최종적으로 판단한다. 본 연구에서는 IEC 60300-3-11을 중심으로 기기나 장치에 대한 RCM분석방법 및 운용방법에 대한 지침을 제공하고자 한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권5호
• /
• pp.258-263
• /
• 2004

The purpose of this experiment is to modify diagnosis criterion of isothermal relaxation current(IRC) measurement equipment which is using for distribution cable diagnosis. We're using this system for several years in the field instead of DC leakage current measurement and lots of cables were replaced. But we have to investigate on the reliability of this equipment for our cables because we didn't carried out condition assessment of extracted cables after field diagnosis by this equipment. It is important thing for cable maintenance. If the replacement criterion is improper we can not prevent failures or will waste budget on account of replacement of the sound cables. In this paper we selected field installed cables and injected silicone fluid to the cables for insulation rehabilitation. In order to prove reliability of the diagnosis equipment we compared diagnosis results and AC breakdown strength according to operating time after silicone treatment. This is the results of the field test for 1 year.

• International Journal of Reliability and Applications
• /
• 제5권2호
• /
• pp.75-80
• /
• 2004

Relationships between inventory policy and operational availability of military equipment maintained under a logistics support system are analyzed. A continuous review inventory model with a stochastic demand typically used in a military logistics support is considered and some numerical studies are provided.

• 드라이브 ㆍ 컨트롤
• /
• 제15권4호
• /
• pp.23-29
• /
• 2018

The objective of this paper is to evaluate the reliability of a volute pump and presents test results through performance and life tests. The performance and life test methods were presented by analyzing the failure modes of the volute pump. Zero failure test time was calculated to evaluate the reliability of the volute pump and then, the test was performed under accelerated conditions. The test was also carried out to check the failure modes of the field conditions. This study can be provided to improve the product reliability through failure analysis of the volute pump. And failure cause of typical failure case has been investigated and improvement design has been presented. The performance test results of before and after the accelerated life test were presented to confirm the improved reliability of the volute pump.