• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2221-2229
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• 2020

After the Fukushima Daiichi nuclear power plant (NPP) accident, level 3 probabilistic safety assessment (PSA) has emerged as an important task in order to assess the risk level of the multi-unit NPPs in a single nuclear site. Accurate calculation of the radionuclide concentrations and exposure doses to the public is required if a nuclear site has multi-unit NPPs and large number of people live near NPPs. So, there has been a great need to develop a new method or procedure for the fast and accurate offsite consequence calculation for the multi-unit NPP accident analysis. Since the multi-unit level 3 PSA is being currently performed assuming that all the NPPs are located at the same position such as a center of mass (COM) or base NPP position, radionuclide concentrations or exposure doses near NPPs can be drastically distorted depending on the locations, multi-unit NPP alignment, and the wind direction. In order to overcome this disadvantage of the COM method, the idea of a new multiple location (ML) method was proposed and implemented into a new tool MURCC (multi-unit radiological consequence calculator). Furthermore, the MURCC code was further improved for the multi-unit level 3 PSA that has the arbitrary number of multi-unit NPPs. The objectives of this study are to (1) qualitatively and quantitatively compare COM and ML methods, and (2) demonstrate the strength and efficiency of the ML method. The strength of the ML method was demonstrated by the applications to the multi-unit long-term station blackout (LTSBO) accidents at the four-unit Vogtle NPPs. Thus, it is strongly recommended that this ML method be employed for the offsite consequence analysis of the multi-unit NPP accidents.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.1
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• pp.15-24
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• 2018

This study analyzed positioning accuracy of the multi-differential global navigation satellite system (DGNSS) algorithm that integrated GPS, GLONASS, and BDS. Prior to the analysis, four sites of which satellite observation environment was different were selected, and satellite observation environments for each site were analyzed. The analysis results of the algorithm performance at each of the survey points showed that high positioning performance was obtained by using DGPS only without integration of satellite navigation systems in the open sky environment but the positioning performance of multi-DGNSS became higher as the satellite observation environments degraded. The comparison results of improved positioning performance of the multi-DGNSS at the poor reception environment compared to differential global positioning system (DGPS) positioning results showed that horizontal accuracy was improved by 78% and vertical accuracy was improved by 65% approximately.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.135-140
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• 2003

This paper is handling about comparative study on dynamic responses of tracked vehicle on soft soil. Two models of tracked vehicle are used in this paper: a single-body model and a multi-body model. Two different methods for dynamic analysis of tracked vehicle are compared: single-body dynamic analysis and multi-body dynamic analysis. Traveling performances of two tracked vehicles are compared.

• Computers and Concrete
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• v.20 no.5
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• pp.555-562
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• 2017

The accuracy and integrity of stress data acquired by bridge heath monitoring system is of significant importance for bridge safety assessment. However, the missing and abnormal data are inevitably existed in a realistic monitoring system. This paper presents a data reconstruction approach for bridge heath monitoring based on the wavelet multi-resolution analysis and support vector machine (SVM). The proposed method has been applied for data imputation based on the recorded data by the structural health monitoring (SHM) system instrumented on a prestressed concrete cable-stayed bridge. The effectiveness and accuracy of the proposed wavelet-based SVM prediction method is examined by comparing with the traditional autoregression moving average (ARMA) method and SVM prediction method without wavelet multi-resolution analysis in accordance with the prediction errors. The data reconstruction analysis based on 5-day and 1-day continuous stress history data with obvious preternatural signals is performed to examine the effect of sample size on the accuracy of data reconstruction. The results indicate that the proposed data reconstruction approach based on wavelet multi-resolution analysis and SVM is an effective tool for missing data imputation or preternatural signal replacement, which can serve as a solid foundation for the purpose of accurately evaluating the safety of bridge structures.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.11
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• pp.1147-1151
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• 2013

A Crankshaft Multi Grinding Machine is developed for manufacturing of high precision crankshaft. The grinding head part of the developed machine should be moved precisely during grinding of work materials. In this paper, structural and modal analysis for the crankshaft multi grinding machine is carried out to check the design criteria of the machine.

• The Korean Journal of Community Living Science
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• v.27 no.1
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• pp.95-108
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• 2016

The objectives of this study are to analyze the characteristics of multi-cultural families in rural areas and to classify their types by applying multi-variate techniques and cluster analyses. Data for the study were obtained by a surveying 120 married migrant females in rural areas of Chungchengnam-do, South Korea. By utilizing the factor analysis to analyze the characteristics of multi-cultural families, 16 basic variables related to these female subjects were categorized into 6 factors: 'marriage length and age', 'language skill of migrant female', 'language skill of husband', 'family satisfaction', 'income and education', and 'general living satisfaction in Korea with remittance'. By appling the cluster analysis, multi-cultural families in rural areas were divided into the following 5 types: 'stable settlement', 'average but stagnant', 'below average yet positive', 'high- income with little communication', and 'young low-income'. In all types, it is strongly recommended to develop various programs regarding vocational education for the migrant females in order to increase their economic opportunities as well as social status.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.11a
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• pp.148-151
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• 2003

Recently school food service operations are confronted with the wide spread pressures for accountability and the need to increase productivity. This paper is concerned with the make-or-buy decision framework for school food service systems considering the multi-attributes in the decision making. For the purpose of considering the multi-attributes analysis method in decision making for the school foodservice, we developed a make-or-buy decision framework using the multi-attribute analysis method, analytic hierarchy process, AHP method for school food service system. Finally, we developed a systematic and practical solution builder for a three-step decision support system in the view of 1) brainstorming for the idea generation, 2) analytic hierarchy process, AHP as a multi-attribute structure ed analysis method, and 3) aggregation logic model to integrate the results of reviewers. We developed web based program and applied it to a school foodservice problem.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.78-83
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• 2016

The development of an exclusive 8-axis multi-tasking machine to finish multiple cutting processes by a single piece of power equipment for securing the high-precision machining and high productivity of the series of shafts (a core part of the automotive powertrain that delivers engine power) is needed. The rigidity of the structure must be improved and the weight of the structure must be reduced to develop a multi-tasking machine with high precision and high productivity. In this paper, we perform a static structural analysis of the initial design of the multi-tasking machines and compare the results of the multi-tasking machines improved by the reinforced design and the results of the initial one. According to the results of the structural analysis, the rigidity of the reinforced machine was increased and the overall weight was decreased. Therefore, the productivity was increased.

• Transactions of Materials Processing
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• v.26 no.3
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• pp.162-167
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• 2017

The tensile surface residual stress in the multi-pass drawn wire deteriorates the mechanical properties of the wire. Therefore, the evaluation of the residual stress is very important. Especially, the axial residual stress on the wire surface is the highest. Therefore, the objective of this study was to propose an axial surface residual stress prediction model of the multi-pass drawn steel wire. In order to achieve this objective, an elastoplastic finite element (FE) analysis was carried out to investigate the effect of semi-die angle and reduction ratio of the axial surface residual stress. By using the results of the FE analysis, a surface residual stress prediction model was proposed. In order to verify the effectiveness of the prediction model, the predicted residual stress was compared to that of a wire drawing experiment.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.185-190
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• 2011

The important use of the desuperheater(multi spray type) changes the superheated steam into the saturated steam. It is more efficient and suitable for using the process. Also, it is more convenient and stable regarding the process temperature control. In this study, transient and quasi-static analysis were done for the evaluation of structural integrity of the multi spray type desuperheater of the power plant. Computational analysis was used to calculate the thermal stress, and the vibration test was done to evaluate the structural stability. This paper is verified by analysis that water spray nozzle(${\phi}=28mm$) shows the best ability. The results show that structural stability of the desuperheater under the real operating condition was proven.