• Journal of Applied Reliability
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• v.12 no.2
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• pp.91-103
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• 2012

Tubular markers for road safety facilities are used to lead the driver's sight line and separate the lanes on the road. Such tubular markers are usually installed on the road and frequently hit by vehicles, they are accordingly requested to assure the product durability. The traditional evaluation method of tubular markers include only quality tests of the material properties. However, most of consuming agencies in charge of road management at fields have proposed problems on long-term performance of the products hit by vehicles under various weather conditions. Therefore, the objectives of this study are to develop the reliability test methods and equipments to simulate the product failures of tubular markers due to vehicle collision and wheel compression and the delamination and discoloration of reflection sheets attached on the surface of the products under high and low temperatures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.751-757
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• 2012

An accelerated life test (ALT) is a test method that forces components to fail more quickly than they would under use conditions by applying higher overstresses. When two or more accelerating stresses are involved in an ALT, an interaction effect may occur. In previous studies, mostly ALTs without considering an interaction of accelerated stresses and accelerated life models were proposed. The life data obtained are extrapolated using a life-stress relationship to estimate the life distribution at use conditions. We use the general log-linear relationship to model the dependence of life in the Weibull distribution on stress. Therefore, this study suggests the acceleration factor model between the lives at use conditions and accelerated conditions by using mechanical component life data considering an interaction effect. Further, the accelerated life test method and acceleration factor model proposed in this paper will be the basis for adopting an accelerated life test with accelerated stress interactions.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1616-1625
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• 2007

Recently, embedded systems role as control systems instead of mechanical control systems in many parts of vehicles. In cases that embedded systems are used controling the electric signal, it is important to secure the reliability of a software within embedded systems. In this paper, the test platform for securing the reliability and real-time characteristic of the embedded system that controls electric signal of All Wheel Steering Control System in a Bi-modal tram is proposed. The platform is built on a HIL (Hardware In the Loop) architecture. Through the HIL platform, various vehicle conditions, driver activities and environment conditions can be successfully tested without actual driving, hence improving the reliability of the embedded system for the All Wheel Steering Control System.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.567-574
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• 2002

Rapid urbanization of many cities require large scale constructions such as high rise buildings in difficult ground conditions. SIP(Soil-cement Injected Precast pile) type piles are tile most popular choice of foundation method in soft ground as well as layered ground in many cities in Korea since SIP offer negligible amount of noise and vibration. But SIP method of construction provide wide range of pile capacity depending on the construction method, equipment, ground conditions and quality control method etc. Therefore this paper intend to investigate the reliability of SIP pile in layered ground through a comparison of existing design formulars and SIP pile load test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1275-1280
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• 2015

A large-sized exciter that vibrates a two-ton component is required to simulate the field operating conditions of a counterweight of an excavator. However, it is difficult for a small-medium sized company to obtain a large exciter for the life test of a counterweight which is an equivalent counterbalancing weight that balances a load. Therefore, in this study, we developed life test equipment for evaluating the reliability of construction machinery weighing about two tons. It simulates the field operating conditions using rotational vibrators consisting of electric motors. A failure analysis of the counterweight was also performed for the major components. Field data acquired from various sites were applied to the life test design of the counterweight. Finally, a zero-failure qualification test based on the accelerated life test was designed, and there was no failure during the test, which guarantees a life of $B_5$ 10,000 hours.

• Korean journal of food and cookery science
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• v.25 no.6
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• pp.725-738
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• 2009

The purpose of this study was to investigate the effects of working conditions on internship satisfaction. Hotel & Restaurant management students at universities in Jeonju participated in this study. Out of 156 questionnaires, 149 were analyzed using SPSS 17.0 and descriptive analysis, frequency test, factor analysis, reliability test, chi-square, t-test, ANOVA, duncan's multiple regression analysis, correlation analysis and regression analysis were used. Based on the result of the conducting factor analysis, the working conditions were classified into 2 factors: work suitability and work environment. Internship satisfaction was classified into 3 factors: internship preference, education and work satisfaction, company satisfaction. Cronbach's alpha was calculated for the reliability of the survey instrument. Consequently, the working conditions were shown to affect internship satisfaction. Among the working conditions, work suitability had a lower effect on internship satisfaction than work environment. At the resort used in this study, the salary level was high, but the level of work environment, internship preference, and company satisfaction was low. The students wanted attend an internship program at the desired place to be hired and found that it was more important to be assigned to the desired department than having a higher salary.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.8
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• pp.625-631
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• 2009

In this thesis, lateral thermosonic bonding with ACFs was investigated as a process to make high reliability joints for FPD fabrication. Conditions for thermosonic and thermocompression bonding with ACFs were determined and used to make specimens in a driving test jig for testing of bond reliability by thermal shock. The results showed that thermosonic bonding temperature of $199\;^{\circ}C$ and bonding time of 1s produced bonds with good reliability. Additionally, thermosonic bonding temperature and time were reduced and thermal shock test results compared to this proposed curing condition. It is concluded that theromosonic bonding with ACFs can be effectively applied to reduce bonding temperature and time compared with that of thermocompression bonding.

• Journal of Applied Reliability
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• v.10 no.2
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• pp.137-148
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• 2010

This study deals with the accelerated life test of high power phosphor converted white Light Emitting Diodes (High power LEDs). Samples were aged at $110^{\circ}C$/85% RH and $130^{\circ}C$/85% RH up to 900 hours under non-biased condition. The stress induced a luminous flux decay on LEDs in all the conditions. Aged devices exhibited modification of package silicon color from white to yellowish brown. The instability of the package contributes to the overall degradation of optical lens and structural degradations such as generating bubbles. The degradation mechanisms of lumen decay and reduction of spectrum intensity were ascribed to hygro-mechanical stress which results in package instabilities.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.179-187
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• 2023

In this paper, we studied the impact of outliers on the power of the significance tests for Cronbach alpha reliability coefficient. Four variables were varied: sample size, the number of items, the number of outliers and population Cronbach Alpha levels. We simulated data using multivariate normal distribution and used outliers sampled from uniform distribution. To test the significance of Cronbach Alpha Reliability, parametric approach(F statistic) and permutation method were used. Consequently, we observed that the powers of permutation test are equal to or greater than those of F test under all conditions, and also both F test and permutation test lose the power as the number of outliers increases, and that these effects of outliers on the power are enhanced for increasing population alpha levels.

• Journal of Applied Reliability
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• v.11 no.2
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• pp.111-126
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• 2011

The clutch coil mounted on the automotive air conditioner is an important part which actuates the clutch to connect or disconnect the pulley and the compressor according to the climate control condition in an automobile. Here, it is generally required that the clutch coil should ensure the long term durability requirement, such as a warranty for the 10 years of field operation or 160,000 km driving, especially in a brand new item, and so forth. However, some difficulties have arisen in restoring its credibility, since domestic specifications for the part have not been yet unified. In order to ensure the reliability, test methods and assessment criteria should be standardized. Moreover, assessed lifetime under specific conditions and potential failure analysis would be important. In this study, lifetime test specifications for the clutch coil have been reviewed and methodological suggestions are provided to ensure reliability, utilizing a quality function deployment through the potential failure mode effect analysis.