• 한국전문물리치료학회지
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• 제28권3호
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• pp.186-193
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• 2021

Background: While the formal test has been used to provide a quantitative measurement of core stability, studies have reported inconsistent results regarding its test-retest and intraobserver reliabilities. Furthermore, the validity of the formal test has never been established. Objects: This study aimed to establish the concurrent validity and test-retest reliability of the formal test. Methods: Twenty-two young adults with and without core instability (23.1 ± 2.0 years) were recruited. Concurrent validity was determined by comparing the muscle thickness changes of the external oblique, internal oblique, and transverse abdominal muscle to changes in core stability pressure during the formal test using ultrasound (US) imaging and pressure biofeedback, respectively. For the test-retest reliability, muscle thickness and pressure changes were repeatedly measured approximately 24 hours apart. Electromyography (EMG) was used to monitor trunk muscle activity during the formal test. Results: The Pearson's correlation analysis showed an excellent correlation between transverse abdominal thickness and pressure biofeedback unit (PBU) pressure as well as internal oblique thickness and PBU pressure, ranging from r = 0.856-0.980, p < 0.05. The test-retest reliability was good, intraclass correlation coefficient (ICC1,2) = 0.876 for the core stability pressure measure and ICC1,2 = 0.939 to 0.989 for the abdominal muscle thickness measure. Conclusion: Our results provide clinical evidence that the formal test is valid and reliable, when concurrently incorporated into EMG and US measurements.

• 품질경영학회지
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• 제45권3호
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• pp.365-377
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• 2017

Purpose: In the A rotorcraft, the division of a long yaw control rod was studied to improve the heat treatment capability. The purpose of this study was to analyze whether division of yaw control rod affects quality reliability in the A rotorcraft and analyze whether it secured flight safety. Methods: The structural static test and the vibration durability test on the split shape of yaw control rod were carried out in order to examine and verify the existing structural analysis results. Results: Structural static test results showed that there were no cracks and vibration durability test results showed that there was no damage or breakage on the split yaw control rod. Conclusion: This study showed that the quality reliability was confirmed and thus the flight safety of the A rotorcraft was secured. And it is expected that the split technique of the yaw control rod will contribute to the development of the rotorcraft industry in the future.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권4호
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• pp.236-242
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• 2014

Since permanent magnet coupling transfers power by magnetic force without contact, it has little shock, vibration, noise. In case of overload, it protects a pump or a motor which is relatively important by slipping internally. In this study, failure analysis and test evaluation on the permanent magnet coupling have been proposed and the process that reliability of the product improves through design improvement has been presented. And failure cause of typical failure case has been investigated and improvement plan has been presented. Finally, reliability improvement is established by analysis of the test results of before and after acceleration test.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권3호
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• pp.208-215
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• 2016

Purpose: ASRP for the domestic development guided missiles requires not only for the reliability evaluation of the products in storage but also for the life cycle management of the products including development prototypes and initial production items. Methods: For this purpose, it should be performed to build a performance database before and after the accelerated aging test with shelf life items including development prototypes and initial production items, based on which the lifetime prediction should also be carried out. In addition, HILS must be applied for the acceptance test with the initial and follow-up production items, and also for ASRP for the long-term storage products in order to secure systematic quality assurance. Results: The results for the life cycle reliability Improving of domestic development of guided missiles are DB building of prescription Item performance, active application of HILS, Management associated with guided missiles life cycle and to Secure technology data about the introduction of foreign guided missiles. Conclusion: Furthermore, it is demanded that DTaQ, the managing agency of ASRP, actively take part in the process to maintain reliability engagement consistency over the life cycle of guided missiles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1203_1204
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• 2009

Korean Tilting trains have tested on conventional lines since the beginning of 2007 for evaluating its reliability. We achieved some major performance tests which are the maximum operation speed 180km/h test and the maximum curves increasing speed with tilting operation test. In order to analysis reliability data of tilting train, we have used the special data aquisition system which consists of monitor, sensors and depot computer etc. As a results of calculation, until now we realized that the reliability are getting more increasing than starting point of running test.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권1호
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• pp.19-30
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• 2013

The requirements of reliability verification for new products and technology are increasing more and more in accordance with the trend change of strength for safety technology, functional skills and emotional quality. In order to conduct the purpose of robust design from the stage of product development recently, the application of reliability technology has gradually increased such as detecting the failure mode throughout the HALT technique, accelerated tests and so on. The main results are as follows; i) through the pre-test and analysis, detected the basic performance and predictable failure mode, ii) HALT technique and process has been developed that can be applied test methods for the next new products.

• 품질경영학회지
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• 제44권3호
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• pp.487-508
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• 2016

Purpose: Current testing method for drying rate used in military textiles has different results according to the public testing institute. So the purpose of this study was to suggest the alternative method which secure the reliability of the drying rate test. Methods: We measured the drying rate by various test methods for military clothes 14 species including quick drying function and compared the test results. Also, the collected data through the test was analyzed using one-way ANOVA. The p-value of results was compared by various testing institutions. Results: The results of this study are as follow; A deviation occurred among the testing institutions in original test method(KS K 0815). Whereas it is verified that there is no deviation among the institutions in 5% significance level by another test method(ISO 17617). Also it would increase work efficiency by reducing the testing time required to test by using ISO 17617. Conclusion: Based on the results, we can suggest the reliable test method of the drying rate.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권3호
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• pp.240-249
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• 2018

Purpose: The purpose of this research is to find which technique, between the PAUT (Phased array ultrasonic test) that has been used widely in practice and RT (Radiographic test) that was used widely in the past, has the higher reliability as a non-destructive testing of welding points in water wall tubes. Methods: To evaluated the reliability of non-destructive testing, eleven test pieces that were fabricated intentionally, which have the most frequently occurred defect types in water wall tubes and then both the PAUT and RT were performed on those eleven test pieces to compare their reliability. Results: The differences of type of defect, length are occurred due to the characteristics of nondestructive testing. The RT could not detect the lack of fusion defect type in specimen #4 and #8 while PAUT could not detect the lateral crack and 1 mm size small porosity in specimen #11. Conclusion: It is concluded that applying both the RT and PAUT result the best reliability rather than applying only one test method, if it is possible, in nondestructive testing of weld water wall tube in thermal power plant boiler case.

• Journal of Power Electronics
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• 제17권3호
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• pp.811-820
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• 2017

The reliability issue of IGBT is a concern for researchers given the critical role the device plays in the safety of operations of the converter system. The reliability of power devices can be estimated from the intermittent life test, which aims to simulate typical applications in power electronics in an accelerated manner to obtain lifetime data. However, the test is time-consuming, as testing conditions are not well considered and only rough provisions have been made in the current standards. Acceleration of the test by changing critical test conditions is controversial due to the activation of unexpected failure mechanisms. Therefore, full investigations were conducted on critical test conditions of intermittent life test. A design optimization process for IGBT intermittent life testing program was developed to save on test times without imposing additional failure mechanisms. The applicability of the process has been supported by a number of tests and failure analysis of the test results. The process proposed in this paper can guide the test process for other power semiconductors.

• 전기전자학회논문지
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• 제19권3호
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• pp.431-439
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• 2015

최근 무기체계에서 소프트웨어가 담당하는 기능이 많아지고, 복잡해지면서 소프트웨어의 품질의 중요성에 대해서 대두가 되고 있다. 소프트웨어의 품질요소는 기능성, 사용성, 유지보수성, 신뢰성이 있으며, 이중 최근 들어 중요시되는 항목이 신뢰성 분야이다. 신뢰성 시험은 분석을 통한 정적 시험과 수행을 통한 동적 시험방법이 있으며, 실수행을 통해 검증하는 동적시험은 정적시험에 비해 많은 기간이 필요하며 복잡성이 높아질 경우 더욱 증가되는 경향을 보인다. 본 논문에서는 다기능 레이더 소프트웨어 개발시 수행한 신뢰성시험 절차 및 결과를 기술하고 이를 통해 효과적으로 시험기간을 줄일 수 있는 신뢰성시험 방법을 제안한다.