• Journal of the Korean Society for Railway
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• v.14 no.1
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• pp.24-30
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• 2011

Conventional slope stability analysis is focused on calculating minimum factor of safety or maximum probability of failure. To minimize inherent uncertainty of soil properties and analytical model and to reflect various analytical models and its failure shape in slope stability analysis, slope stability analysis method considering simultaneous failure probability for multi failure mode was proposed. Linear programming recently introduced in system reliability analysis was used for calculation of simultaneous failure probability. System reliability analysis for various analytical models could be executed by this method. For application analysis for embankment, the results of this method shows that system stability of embankment calculate quantitatively.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.297-300
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• 2004

This paper proposes a method for choosing the best composite power system expansion plan considering probabilistic reliability criterion. The proposed method was modeled as the minimization of the investment budget (economics) for constructing new transmission lines subject to not only deterministic(demand constraint) but also probabilistic reliability criterion(LOLE) with considering the uncertainties of the system elements. This is achieved by modeling the power system expansion problem as an integer programming one. The method solves for the optimal strategy using a probabilistic theory based branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. Although the proposed method is applied to a simple sample study, the test results demonstrate a fact that the proposed method is suitable for solving the power system expansion planning problem subject to practical uncertainties for future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3034-3055
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• 2014

Wireless Sensor Networks have extensively been utilized for ambient data collection from simple linear structures to dense tiered deployments. Issues related to optimal resource allocation still persist for simplistic deployments including linear and hierarchical networks. In this work, we investigate the case of dimensioning parameters for linear and tiered wireless sensor network deployments with notion of providing extended lifetime and reliable data delivery over extensive infrastructures. We provide a single consolidated reference for selection of intrinsic sensor network parameters like number of required nodes for deployment over specified area, network operational lifetime, data aggregation requirements, energy dissipation concerns and communication channel related signal reliability. The dimensioning parameters have been analyzed in a pipeline monitoring scenario using ZigBee communication platform and subsequently referred with analytical models to ensure the dimensioning process is reflected in real world deployment with minimum resource consumption and best network connectivity. Concerns over data aggregation and routing delay minimization have been discussed with possible solutions. Finally, we propose a node placement strategy based on a dynamic programming model for achieving reliable received signals and consistent application in structural health monitoring with multi hop and long distance connectivity.

• Earthquakes and Structures
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• v.21 no.5
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• pp.505-514
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• 2021

A formulation based on structural reliability and cost effectiveness is proposed to provide recommendations to select the best retrofit strategy for schools with reinforced concrete frames and masonry walls, among three proposed alternatives. The cost calculation includes the retrofit cost and the expected costs of failure consequences. Also, the uncertainty of the seismic hazard is considered for each school site. The formulation identifies the potential failure modes, among shear and bending forces for beams, and flexure-compression forces for columns, for each school, and the seismic damages suffered by the schools after the earthquake of September 17, 2017 are taken into account to calibrate the damaged conditions per school. The school safety level is measured through its global failure probability, instead of only the local failure probability. The proposed retrofit alternatives are appraised in terms of the cost/benefit balance under future earthquakes, for the respective site seismic hazard, as opposed to the current practice of just restoring the structure original resistance. The best retrofit is the one that corresponds to the minimum value of the expected life cycle cost. The study, with further developments, may be used to develop general recommendations to retrofit schools located at seismic zones.

• Journal of the Korean Data and Information Science Society
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• v.21 no.1
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• pp.173-177
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• 2010

It is well known that if the parent distribution has a nonnegative support and has increasing failure rate, then all the order statistics have increasing failure rate (IFR). The result is not necessarily true in the case of bivariate distributions with dependent structures. In this paper we consider a symmetric bivariate exponential distribution and show that, two marginal distributions are IFR and the distributions of the minimum and maximum are constant failure rate and IFR, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.332-336
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• 1991

Network management is responsible for gathering information on the usage of the network media by the network devices, ensuring the correct operation of the network, and providing reports. MAP network management must provide the high reliability of the media and signaling method, even in very harsh environments, providing a very low bit error rate and minimum number of retransmission. In this paper, we analysed the framework of OSI management and MAP network management and discussed the implementation method of fault management and remote management mechanism in the Mini-MAP controller developed for IBM-PC.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1457-1459
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• 2000

The ATO(Automatic Train Operation System) system is equipment for automatic and driverless operation of electric train with minimum control of operator. In this paper, we made ATO system with national technic and passed type test. We are convinced of reliability and safety of the ATO system on the seoul metro 7 line.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.15 no.25
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• pp.83-90
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• 1992

This paper aims at the problem that design the network of Rig-star type with the minimum cost, which the Ring is composed of the selected nodes(concentrators) among the several candidate nodes on the network and other nodes(terminals) is connected to the Ring by star subnetwork. Especially, we consider the terminal reliability in network design problem. We develop the heuristic algorithm for network design problem to obtain the near optimal(best) solution for problem. We use an add-heuristic method and 2-exchange method in developing the heuristic algorithm.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.119-126
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• 2002

A reliability analysis is performed to investigate the influence of the uncertainty from few in-situ samples and inherent heterogeneity of the ground on the probability of failure for a rock cut slope. The results are compared with those of deterministic slope stability analysis. The random variables used are unit weight of the rock, the angle of potential slope of failure, and cohesion and internal friction angle of joints. It was found that the rock slope in which the factor of safety satisfied the minimum safety factor in the deterministic analysis has high probability of failure in the reliability analysis when the weak geological strata are involved in the cut slope. The probability of failure of rock slope is most sensitive to the mean and standard deviation of cohesion in rock joint among the random soil parameters included in the reliability analysis. Sensitivities of the mean values are larger than those of standard deviations, which means that accurate estimation of the mean for the in-situ geotechnical properties is important.

• Korean Journal of Community Nutrition
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• v.19 no.3
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• pp.258-273
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• 2014

Objectives: The purposes of the study were to develop a questionnaire for dietary habit survey for Korean adults, and unify the terms related to dietary habits. Methods: The Delphi method by 43 professionals on dietary habit research was applied to unify the terms. Results: With regard to results on terms related to dietary habit, the respondents recorded the highest percentage (90.7%) of selecting the term "dietary habits" and also the highest percentage (76.7%) of choosing "dietary habits" for English. The biggest percentage of the respondents chose "individual dietary behaviors repeatedly formed and habitualized under the social, cultural, and psychological influence in the group" as the concept of dietary habits. The Delphi survey for the development of a questionnaire resulted in the first questionnaire of 31 items, the second one of 27 items, and the third one of 25 items. The validity of questionnaire items was tested with content validity ratios (CVR). The items whose CVR value was 0.29 or lower were eliminated or revised, because the minimum CVR value needed to test validity was 0.29. To test the reliability of questionnaire items, test-retest method was performed in 163 adults. According to the Kappa coefficient in the range of 0.314-0.716, all of the 25 items were in the reliability scope. A survey was taken with 702 adults to finally revise and supplement the third questionnaire whose validity and reliability were tested. Conclusions: Through those processes, a questionnaire for adults' dietary habit survey was finally completed. The significance of the study lies in the development of the first questionnaire on dietary habits equipped with both validity and reliability in South Korea.