• Computers and Concrete
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• v.12 no.1
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• pp.65-77
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• 2013

This paper examines the dynamic response of an arch dam subjected to blast loading. A damage model is developed for three dimensional analysis of arch dams. The modified Drucker-Prager criterion is adopted as the failure criteria of the damage evolution in concrete. Then, Xiluodu arch dam serves as an example to simulate the failure behaviors of structures with the proposed model. The results obtained using the proposed model can reveal the reliability degree of the safe operation level of the high arch dam system as well as the degree of potential failure, providing a reliable basis for risk assessment and risk control.

• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.411-420
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• 2014

The water resources sustainability is becoming an important issue in consideration of hydrologic uncertainty by global warming and climate change. This study is to assess the water supply performance for the major multipurpose dams using sustainability index. Parameters, mostly utilized in water resources system assessment, are selected in respect of applicability and flexibility, and those parameters are used as a variable of the composite index. In practice, the composite index including reliability, resiliency, vulnerability and maximum deficit are applied to 15 multipurpose dams and 4 major basins. And to conclude, Daechungdam in the Geum river basin and Imhadam, Hapchondam and Namgangdam in the Nakdong river basin show low sustainability comparing with other dams. The Nakdong river basin needs to develop alternatives to improve water supply stability because it indicates the most poor sustainability level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.158-167
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• 2016

This study was conducted to evaluate the quality of meta-analysis of social work in South Korea using the Assessment of Multiple Systematic Review (AMSTAR). Electronic databases including the Korean Studies Information Service System (KISS), DBpia, and RISS4U were searched for 'meta-analysis', 'social work', and 'social welfare' from 2000 to December 2015, and 42 meta-analysis studies were included. Data were analyzed using descriptive statistics, t-tests, and ANOVA. The mean score for AMSTAR evaluation was $4.766{\pm}1.66$, while 19 studies (45.2%) were classified at the low-quality level, and 22 (52.4%) were at the moderate-quality level. The scores of quality assessment were analyzed by publication year, participants, number of studies included, number of DB, reporting study quality, extraction diagram and topics. The findings indicated that the following changes should be implemented to improve the quality and reliability of meta-analysis results in social work research: 1) common reporting guidelines should be provided for the social work field, 2) quality analyses of each study should be conducted to achieve a high level of evidence of effectiveness of social work interventions, 3) the characteristics of the included studies should be provided, and 4) a consensus and procedure based on at least two independent data extractors should be reported.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.4
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• pp.281-294
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• 2012

The current status of the computer codes for the analysis of coupled thermal-hydrological-mechanical behavior occurred in a high-level waste repository was investigated. Based on the reported results on the comparison between the predictions using the computer codes and the experimental data from the in-situ tests, the reliability of the existing computer codes was analyzed. The presented codes simulated considerably well the coupled thermal-hydrological-mechanical behavior in the near-field rock of the repository without buffer, but the predictions for the engineered barrier system of the repository located at saturated hard rock were not satisfactory. To apply the current thermal-hydrological-mechanical models to the assessment of the performance of engineered barrier system, a major improvement on the mathematical models which analyze the distribution of water content and total pressure in the buffer is required.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.495-504
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• 2009

As the Reliability Centered Maintenance(RCM) is being studied, maintenance tasks can be performed effectively through the Risk Priority Number(RPN) evaluation about the components in the system. The RPN is usually calculated through arithmetical operations of three values, Severity, Occurrence, and Detection for each facility. This RPN provides information that includes risk level of the facility and the priority order of maintenance tasks for facility. However, if there is no sufficient historical failure data, it is difficult to calculate the RPN. In this case, historical failure data from other sources can be used and apply this data to korean railway system. In this paper, it is proposed that a new methodology to model the failure rate as a fuzzy membership function. This method is based on failure data from other sources by means of the fuzzy theory and the expert opinion system. And considering assessment tendency of each expert, distortions that happened when the failure rate of facilities is estimated were minimized. This results determine Occurrence values of facilities. Taking advantage of this result., the RPN can be calculated with Severity and Detection of facilities by using the fuzzy operation. The proposed method is applied the rail-way power substation.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.9
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• pp.431-439
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• 2001

This Paper illustrates a new numerical analysis method using a nodal effective load model for nodal probabilistic production cost simulation of the load point in a composite power system. The new effective load model includes capacities and uncertainties of generators as well as transmission lines. The CMELDC(composite power system effective load duration curve) based on the new effective load model at HLll(Hierarchical Level H) has been developed also. The CMELDC can be obtained from convolution integral processing of the outage capacity probabilistic distribution function of the fictitious generator and the original load duration curve given at the load point. It is expected that the new model for the CMELDC proposed in this study will provide some solutions to many problems based on nodal and decentralized operation and control of an electric power systems under competition environment in future. The CMELDC based on the new model at HLll will extend the application areas of nodal probabilistic production cost simulation, outage cost assessment and reliability evaluation etc. at load points. The characteristics and effectiveness of this new model are illustrated by a case study of MRBTS(Modified Roy Billinton Test System).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.538-544
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• 2021

Technology readiness assessment is a procedure for managing defense project risk factors based on the preemptive identification of technical risks. Under current regulations, technology readiness is determined based on considerations of the ratings of factors itemized on a checklist, whether unsatisfied factors have a fatal impact on the project, and whether countermeasures for unsatisfied factors have been established. However, objective criteria for assessing the impact of unsatisfied factors have not been presented, and thus, at present, the results of technology readiness level determinations are largely subjective. In addition, the importance of questions on the checklist is dependent on individual project characteristics and this is not considered during the assessment process. In this paper, we propose an improved technology readiness assessment procedure that considers the characteristics of each project. Using the proposed procedure, we quantitatively determined the importance of each checklist item using a weighting method. We found the devised procedure improved the reliability and objectivity of technology readiness assessment results. A case analysis of a complex weapons system is presented to demonstrate these improvements.

• Journal of The Korean Association For Science Education
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• v.22 no.1
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• pp.176-189
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• 2002

The purpose of the study is to develop major types of scoring rubrics of portfolio system, and estimate the reliability of the rubrics developed. The portfolio system was developed by Science Education Laboratory, Chongju National University of Education in summer, 2000. The portfolio is based on the Unit 2, The Layer and Fossil, and Unit 4, Heat and Change of Objects at fourth-grade level. Four types of scoring rubrics, holistic-general, holistic-specific, analytical-general, and analytical-specific, were developed. Students' portfolios were scored and inter-rater and intra-rater reliability were calculated. To estimate inter-rater reliability, 3 elementary teachers per each rubric(total 12) scored 12 students' portfolios. Teachers who used analytical-specific rubric scored only six portfolios because it took much more time than other rubrics. To estimate intra-rater reliability, second scoring was administered by two raters per rubric in two and half month. The results show that holistic-general rubric has high inter-rater and moderate intra-rater reliability. Holistic-specific rubric shows moderate inter- and intra-rater reliability. Analytical-general rubric has high inter-rater and moderate intra-rater reliability. Analytical-specific rubric shows high inter- and intra-rater reliability. The raters feel that general rubrics seems to be practical but not clear. Specific rubrics provide more clear guidelines for scoring but require more time and effort to develop the rubrics. Analytical-specific rubric requires more than two times of time to score each portfolio and is proved to be highly reliable but less practical.

• Transactions of the KSME C: Technology and Education
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• v.5 no.2
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• pp.115-126
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• 2017

This paper proposes an accelerated life evaluation of drive shaft for the power train parts of special purpose vehicle. It is necessary the real load data of usage level driving load condition for life evaluation of power train parts, but we can't get the load spectrum data for evaluation in many case of special purpose vehicle. So, in this paper, the road load spectrum data for evaluation is created by modeling and simulation based on vehicle data and special road condition. The inverse power model is used for accelerated life test. The equivalent torque of load spectrum is achieved using the Miner's Rule. This paper also proposes the calibrated acceleration life test method for drive shaft. The fatigue test is performed through three stress levels. The lifetime at normal stress level is predicted by extrapolation, and is verified through comparison of experimental results and load spectrum data.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.730-734
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• 2007

In this paper, we suggest the criticality of Hidden Failure with regard to the design of watch dog timer, used to detect HALT on railway signaling embedded controller, via FMEA and FTA. Hidden Failure means reliability and safety degradation of the system due to any failure occurred on elements added for fault tolerance. In this paper, therefore, we design vital watch dog timer to prevent the system from operating in low SIL conditions and assess the safety of circuit on failure occurrence to demonstrate that safety degradation problems owing to existing design are supplemented.