• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.257-264
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• 2011

In this study, we performed sensitivity study of the $217Plus^{TM}$ system model to various parameters. Specific attention was put to logistics model and its behavior has been examined in terms of non-component failure causes. We first briefly explained the $217Plus^{TM}$ methodology with system level failure rate evaluation. We then applied experimental designs with several failure causes as factors. We used an orthogonal array with three levels of each parameter. Our results indicate that cannot duplicate, induced, and wear-out causes have dominant effects on the system failures and design, parts, and system management have much less but a little strong effects. The results in this study not only figure out the behavior of the predicted failure rate as functions of failure causes but provide meaningful guidelines for practical applications.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.894-903
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• 2011

In this paper, the capability index is introduced in order to improve the reliability of new concept machine tools and the method to improve the machine accuracy from the analysis of cutting process, statistical methodology and influence factors are proposed. In addition, the rib structure of bed and column in machine tools is analyzed by using the thermal impact method in order to analogize the rib pattern which has the small thermal deformation under thermal boundary condition. In the analysis of column rib structure, thermal boundary condition is separated to heat conduction and heat transfer to appropriate real boundary condition. Finally, performance chart of bed and column rib structure is provided for designer to estimate each rib pattern and select rib structure appropriating to thermal condition.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1841-1843
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• 1996

To meet recent increasing demand for electric power in large cities in Korea, and to improve reliability of the power supply. Especially, demand for electric power apparatus places great emphasis on not only function but also environmental factors. In this paper, environpolitics describes according to large capacity demand for extra high voltage underground transmission lines and high reliability of the power supply.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.114-121
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• 2004

The sensor and measuring instrument that are used for the infrastructure is discussed the reliability problem from the various environment factors. In the domestic infrastructure, the low reliability products are produced, because of lack of the pertinent test methods and equipments. To improve the practical use and accuracy of the sensor, it raises the measurement reliability about the sensor and measurement instrument. In this study, the variance of the displacement value according to temperature was investigated using the LVDT for the infrastructure. The experimental results showed that a sensor is affected by environment factor such as temperature.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1531-1535
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• 2008

In the past vertically integrated power system, the power utility forecasted power demand and invested new power plants to keep a system adequacy. However, in the competitive electricity markets, a principle part of the capacity investment is market participants who decided the investment to maximize their profit. Especially, one of the main factors in their long-term decision making is the retrieval of fixed costs (construction costs). This paper presents the capacity payment in electricity power markets. The capacity payment (CP) in Cost Based Pool (CBP) is needed to recover fixed costs. However, CP in CBP was applied not only recovering fixed costs but also ensuring supply reliability. In order to operate harmonious power markets, pool needs reasonable CP mechanism. This paper analysis CP using capacity proportion and Reliability Pricing Model (RPM).

• The Korean Journal of Applied Statistics
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• v.16 no.2
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• pp.225-237
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• 2003

We analyze the factors leading to discrepancy in estimators and predictors of e-commerce size each survey institution, and then we make a evaluation criterion to obtain objective and standard results in e-commerce surveys. We would like to guarantee reliability for e-commerce statistics published by the survey institutes and the public ones by adapting the criterion which suggested.

• Korean Journal of Organic Agriculture
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• v.20 no.2
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• pp.125-142
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• 2012

The purposes of this study are to analyze the effect of consumption of environment-friendly agricultural products (EFAP) on improvement of family health, and to suggest directions for improvement of family health. A survey was conducted for qualitative analysis regarding relationship between EFAP consumption and family health. The method of his study was employed Cross-tabulation and an Ordinal Logistic Regression Model to derive more significant results in analyzing factors of improvement of family health. The result shows that improvement of health has a significant positive relationship with consumption of EFAP. In addition, those consumers with high reliability and quality contentment are more likely to experience improvement of health. As consumers constantly eat EFAP, they are more likely to experience improvement of health. In order to provide consumer reliability of EFAP, more strict certification management system with sound monitoring and an appropriate penalty for violation should be established.

• The Mathematical Education
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• v.46 no.3
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• pp.263-272
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• 2007

Mathematics Teaching Efficacy Beliefs Inventory (MTEBI) was translated into Korean and conducted among Korean pre-service mathematics teachers. The Korean-translated MTEBI consists of two subscales with 16 items. Personal Mathematics Teaching Efficacy (PMTE) subscale has 10 items and Mathematics Teaching Outcome Expectancy (MTOE) subscale has 6 items. The purpose of this study is to investigate the internal reliability and the construct validity of the Korean-translated MTEBI. The Cronbach alpha coefficient of Korean-translated MTEBI and its two subscales are respectively .87, .83, and .74 which imply that the instrument is reliable. The construct validity was achieved by performing factor analysis. Principal component solution with varimax rotation for the Korean-translated MTEBI was used in factor analysis and thus the best fit simple structure was obtained by two factors which correspond to the self-efficacy dimension and the outcome expectancy dimension of Bandura's self-efficacy theory.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.3
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• pp.223-234
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• 1998

In this study, an attempt is made to apply the concept of fuzzy-bayesian theory to the integrity assessment of structure system, and uncertainty states are represented in terms of fuzzy sets which define several linguistic variables such as "very good", "good", "average", "poor", "very poor", etc. Especially, the concept of fuzzy conditional probability aids to derive a new reliability analysis which includes the subjective assessment of engineers without introducing any additional correction factors. The fuzzy concept are also used as reliability indexes for the condition assessment based on the proposed models, the proposed fuzzy theory-based approach with the results of PEM and AFOSM are applied to retaining wall.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.29-35
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• 2006

Trains in LRT(Light Railway Transit) system usually have shorter car length than metro's because of their smaller passensers demand. Therefore it is very likely that the load condition of LRT system in abnormal operation, in case of which trains are in close proximity by system broke or train rescue works, could be worse rather than in normal operation, in spite of rare probability of abnormal operation. In this study, the target reliability indexes of several abnormal operations are estimated in accordance with the occurrence probabilities of each abnormal operation case and the reliability index of normal operation presented by the specification. From the indexes, load factors for the abnormal operation cases are estimated and the safety evaluation is performed for Yong-in LRT project.