• Journal of Applied Reliability
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• v.11 no.2
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• pp.127-140
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• 2011

This paper presents an accelerated life test of aviation taxiway lights installed in the airport to help safe navigation of airplanes at night or in bad weather. Recently halogen lamps of taxiway lights are replaced by LED ones and their reliability needs yet to be verified. Thus, effective test conditions are designed reflecting the failure modes and mechanisms from the previous studies on LED, which include the accelerated degradation process. The test is performed under the temperature $70^{\circ}C$ and $90^{\circ}C$ for two types of LED lights, taxiway center line lights(TCLL) and taxiway edge lights (TEDL). The failure time data were analyzed using lognormal distribution and Arrhenius model to find the life-stress relationship, acceleration factor and life characteristics under the normal condition temperature $30^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.182-183
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• 2006

It has been studied about the important consideration in designing and construction of the reliability assessment facilities including the combined testing system for simulating condition of acceleratedly deteriorated environment, which enable to test and evaluate the large-sized HV power apparatus without any disassembly up to transmission class in this paper. Also it is described simply about its ratings and main technical specifications and trial running of the system. To evaluate the performance characteristics against combined test condition for various power installation, especially for the polymer type insulators and kinds of bushings, brief investigation and an analysis of test objects and related international codes and standards have been conducted.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.158-164
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• 2006

The creep behavior of newly developed composite geogrids which consists of PET yarns sheathed in PP were evaluated using SIM. For the SIM procedure, three test parameters, the applied loads, temperature steps and number of ribs were investigated, The study confirmed that temperature steps of 10 and 14$^{\circ}C$ up to 80$^{\circ}C$ are applicable for composite geogrids due to the different transition temperatures between two materials. At applied loads of 40 and 50%, only primary creep state was measured, while secondary creep state appeared at the applied loads of 60%, The lifetimes of composite geogrids were estimated at each of loading level using statistical reliability analysis technique. The results show that the lifetimes longer than 100 years can be predicted within 16 hours. Therefore, SIM is very effective and economical accelerated creep test methods, especially for lifetime prediction. This gives guidelines for users to select the appropriate factor of safety against creep considering the field condition within shorter test times.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2100-2102
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• 2005

In this Paper, there have been brief review about the important consideration in laboratory planning and designing the dielectric testing facilities for heavy electric apparatus up to 800kV-class in the high voltage testing fields. To improve and reinforce the existing dielectric test facilities in the way of econo-mical and optimal condition, wide investigation and an analysis for a solution, especially overshoot compensation method. have been suggested. With the brief description about those matters in constructing and improving the test facilities, the specification of each facility has been shown in the paper.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.403-405
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• 2003

본 논문에서는 대전류 표준측정에 대한 STL TC의 Ad-Hoc Working Group의 최종방안에 대해 자세히 소개하여 이를 계기로 국내에서도 필요한 사전준비에 만전을 기하고자 한다. 향후 연속적으로 해야 할 업무, Shunt의 소유, 경비 지불방법 등에 대한 사항과 함께 우리나라 대전류 표준측정시스템의 구축절차를 제안하였으며, 이를 통해 대전류 측정에 있어서 국제표준과의 소급성을 확보할 수 있기 때문에 국내에서 시행하는 각종 시험에서 대전류 측정이 국제적으로 유효하게 될 것이다.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.409-411
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• 2003

본 논문에서는 대전류 표준측정에 대한 STL TC의 Ad-Hoc Working Group의 최종방안에 대한 기술적 배경을 소개하여 이를 계기로 국내에서도 대전류 표준확보에 필요한 사전준비에 만전을 기하고자 한다. STL의 대전류 reference shunt 요구사항, 측정 불확도 및 각 시험소에서 교정하여야 할 사항 등에 대하여 검토하고, 우리나라 대전류 표준측정시스템의 구축필요성, 구축절차 및 방안에 대하여 기술한다.

• Journal of the Korean Home Economics Association
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• v.39 no.10
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• pp.169-186
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• 2001

The purpose of the study was to verify validity and reliability of performance assessment in home economics by applying performance assessment tools developed by Korean Curriculum Assessment Institute and by the researcher to a class of 17 high school female students in a rural area. For the purpose of this study, the research question was formulated and addressed:“How are the validity and reliability of performance assessment in home economics\ulcorner” The results of the study were as follows. 1. The results of testing validity a. Thirteen high school home economics teachers, whose average teaching years is ten years verified high validity in the contents of performance assessment. b. In the validity of the items that is verified being based on the scores of high school entrance examination of 2000 school year, the essay type showed its characteristics as performance assessment. c. The generalizability among assessment methods was not high. 2. The results of testing reliability Both Cronbach's $\alpha$, inter-item reliability of the assessment tools used in the research, and reliability among the raters were high. But reliability among the tasks was relatively low. This study proposed that the diverse performance methods, the increasing number of assessment, the explicit assessment criterion, and scoring criterion are needed to satisfying validity and reliability of performance assessment.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.4
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• pp.407-414
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• 2002

The inherent reliability of a product is primarily determined in the design stage, and therefore, design engineers should be able to design reliability into the product in an efficient manner. Especially, the product should be designed such that its reliability is robust to various noise factors encountered in production and field environments. The Taguchi method can be effectively used for this purpose. However, there exist only a few attempts to integrate the Taguchi method with reliability design, and in addition, the existing works do not sufficiently consider the robustness and/or the distinction between noise and acceleration factors. This paper develops a unified approach to robust reliability design assuming that accelerated life tests are conducted at each combination of design and noise conditions. First, an experimental structure for assigning not only acceleration but also noise factors is presented. Second, the reliability at the use condition is estimated using the assumed accelerated life test model. Third, reliabilities are transformed into 'efforts' using an effort function which reflects the degree of difficulty involved in improving the reliability. Finally, an optimal setting of design parameters is determined based on the mean and standard deviation of the effort values. The above approach is illustrated with an example of a paper feeder design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.397-403
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• 2015

This paper proposes the development of a method for assessing the system reliability of an unmanned control robot system for an excavator. It then shows the results of the reliability qualification test based on the proposed method. The robot system functions to ensure the safety of the workers who control excavators in dangerous working environments, and the system reliability was calculated by integrating the reliabilities of the system components. Thus, test equipment for the three key units of the robot system were constructed and used in accelerated life testing. From the life testing results, guaranteed mean time between failures for the chosen confidence level was estimated, and the reliability qualification testing method of the robot system using small sample sizes was proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.406-418
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• 2020

When developing weapons systems, it is important to implement the functions and performance of equipment suitable for development purposes, but it is very important to ensure that the equipment is capable of operating without any vacuum with reliability after development. Therefore, various activities are carried out to enhance reliability of equipment. Reliability is enhanced by using high-specification parts in development, reliability verification through analysis, and testing using development prototypes to reinforce and improve the parts that are lacking in equipment. However, recently, development schedules are shortened due to rapidly changing external conditions and technologies, and there are cases where sufficient reliability growth activities were not carried out due to problems such as cost. Examples are projects that perform reliability activities only in analytical methods (reliability, FMECA). In this paper, analyzing and testing methods for analysis and testing were carried out on the same equipment through FMECA and super-accelerated life test, the contents of reliability growth activity were derived, the results of design change/review were accordingly compared, the differences between the two methods were analyzed, and measures were proposed to strengthen reliable growth activities. It was concluded that reliable growth activities through analysis from the beginning of development and reliable growth activities through testing should be carried out at the completion of initial prototype production.