• Journal of Applied Reliability
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• v.10 no.1
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• pp.1-9
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• 2010

In general, the performance of a component degrades as time goes by and failure of a component occurs when the performance degradation reaches a pre-specified level. It is difficult to obtain the failure time distribution data or the necessary number of failure data especially for the metal or machine part. Thus, a design of reliability qualification test based on performance distribution is more effective than failure time distribution. In this study, a performance-based reliability qualification test is developed and a numerical example is provided to illustrate the use of the developed reliability qualification test. This approach could be applied to many kinds of metal or machine part whose magnitude of strength could not be evaluated during at any random points but judgement can be made by only failure of the part. Besides, it is also possible that any parts which have a similar failure characteristics could be applicable to the developed reliability qualification test.

• Journal of Applied Reliability
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• v.14 no.2
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• pp.114-121
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• 2014

An environmental test has been performed in order to improve the lifetime and reliability of the electrical units on aircraft. However, faults occurring in the field of aircraft have been difficult to predict and prevent, and new concepts for reliability testing are desired. Therefore, a composite reliability test sequence was proposed in the conventional studies. This study introduces test sequence guidelines based on relevant principles and considerations for electronic testing according to International Standard IEC-60068-1 and the United States Military Standard MIL-STD-810G. In addition, we analyze possible causes of failure using two-step QFD based on aircraft operation scenarios. Finally, the proposed test sequence can reproduce various and realistic failure modes for electrical units on aircraft.

• Journal of Applied Reliability
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• v.7 no.2
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• pp.57-72
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• 2007

This paper suggests an approach for using ALTA 7 PRO to design accelerated life test plans. Conducting a accelerated life test requires finding life distributions at different stress levels and determining an appropriate life-stress relationship. Moreover, a test plan needs to be developed. In its optimal test plan, stress levels are determined and the proportions of test units are assigned at each stress level so that asymptotic variance of the maximum likelihood estimate of a (log) percentile of the life distribution at the design stress is minimized. Examples are presented for usage.

• The KSFM Journal of Fluid Machinery
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• v.8 no.1 s.28
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• pp.16-22
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• 2005

This paper presents the method of ROL(Rate Of Loading) improvement for the Motor Operated Gate Valve operated in high differential pressure condition. ROL is one of the most important evaluation parameters for the valve ability. It is close to correlation in stem factor (SF) and appears different value by the differential pressure of fluid. ROL and SF are analyzed by the static test and dynamic test. The obtained result show that the modification of stem factor is very important factor for the ROL improvement. In order to obtain the same value of SF between static and dynamic test, stem and stem nut should be combined appropriately by the repetition test.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.9-12
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• 1993

This study investigated the propriety and the extension of the term of validity about the using watthour meters at present. The subject of study is 1Cent 2W 220V 30(10)A, 1Cent 3W 110V 30(10)A of model III watthour meters. They are the used metes(products in 1984) and the repaired meters(products in 1977) in the end of the period. The investigation is as follows. o Investigation of external appearance o Driving current test o Creeping test o Noise test o Error test o Durability test. Results of the study have been the number of 13.3% exceeded permitting error and the number of 31.3% failed in endurable test of 500 hours. So, the using meters are not suitable to extend the term of validity without the improvement of several characteristics.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.192-194
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• 2009

This study presents on the analysis fire hazards of communication cable. In order to analyze fire hazards fire retardant tests and con-calorimeter test is conducted. The fire retardant tests are IEC 60332-1 and UL 94 test. The results show that IEC 60332-1 test and It 9t test are not effective to estimate fire hazard. And various parameter is obtained by con-calorimeter test. It is necessary to analysis effectively fire hazards of cable for new fire retardant test.

• Journal of Applied Reliability
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• v.4 no.1
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• pp.1-14
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• 2004

Accelerated life test models and procedures are developed to assess the reliability of typical power relays. The main function of relays is to control high voltage circuits by operating low voltage circuits. The accelerated life test method and test equipments are developed using the relationship between stresses and life characteristics of the products. Using the developed accelerated life test method, the parameters of the ALT model and lifetime distribution are estimated and the reliability of the relays at use condition is assessed. The proposed accelerated life test method and procedure may be extended and applied to testing similar kinds of products to reduce test time and costs of the tests remarkably.

• Journal of Applied Reliability
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• v.11 no.1
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• pp.1-15
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• 2011

Automobile markets are so fierce in the world market that every major manufacturer assure the buyer of the car by give a provocative warranty plan for their cars. For instance Hyundai motor company offer 10 years and 100,000 miles of warranty whichever comes first. But in order for this effort to be successful every critical component such as window switch has to be proven to be reliable in an adverse environment. Therefore, in this article reliability assessment criteria for window switch are established in terms of basic performance test, environment test and life test.

• Journal of Aerospace System Engineering
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• v.10 no.1
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• pp.29-34
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• 2016

Flutter wind-tunnel test is an expensive and complicated process. Also, the test model may has discrepancy in the structural characteristics when compared to those of the real model. "Dry Wind-Tunnel" (DWT) is an innovative testing system which consists of the ground vibration test (GVT) hardware system and software which computationally can be operated and feedback in real-time to yield rapidly the unsteady aerodynamic forces. In this paper, we study on the aerodynamic forces of DWT system to feedback in time domain. The aerodynamic forces in the reduced-frequency domain are approximated by Minimum-state approximation. And we present a state-space equation of the aerodynamic forces. With the two simulation model, we compare the results of the flutter analysis.

• Journal of the Korean Arthroscopy Society
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• v.1 no.1
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• pp.26-30
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• 1997

Recently, the incidence of anterior cruciate ligament injury is rapidly increasing because many young Korean are actively participating in sports activities including basketball, skiing and soccer. Sometimes acute ACL injuries arc misdiagnosed as sprain because of pain and muscle spasm. An accurate physical examination and careful history taking are very important to diagnose the ACL injuries. Therefore author described the skill of history taking and the technique of physical examination to diagnose ACL injuries. The most sensitive test is the Lachman's test, which is performed with the knee in 200 of flexion, the femur stabilized with full flexed examiner's knee placed behind patient's distal thigh and one hand of examiner, and the proximal tibia grasped with the other. The pivot shift test is a passive motion test that attempts to subluxate the tibia anteriorly, then have it reduce rapidly. The pivot shift test is very sensitive test to diagnose the chronic ACL injuries.