• 한국농촌건축학회논문집
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• 제15권2호
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• pp.41-51
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• 2013

In the midst of growing demand for rural life of urban dwellers, this study tried to investigate the difference in behavior and recognition about urban rural exchange between Korea and Japan. For this, this study utilized 2,000 total samples of the survey conducted by MLIT in Japan, because Japan has experienced a low birth rate and aging population earlier and actively promoting urban rural exchange program than South Korea. The result of the analysis is as follows. First, the needs for rural life of urban dwellers are similar both in Japan and South Korea. However, Japanese prioritize future efforts to current efforts. Second, urban dwellers' activities in rural areas were classified into three categories; field trips and hands-on activities, cruise and circulating activities, and leisure activities. Third, similarly three types of visit or intercourse of urban dwellers into rural areas were classified; repeatedly visit the same place as 'iterative type', visit a new place as 'new pioneer type', and not yet determined as 'undefined type'. Variables such as age of household, income, number of inmate, and number of children were analyzed linked to these three types of visit or intercourse in a Discriminant analysis. As a result, only 'age of household', however, turned out to be the crucial factor which influence decisively distinguishing characteristics of these three types of visit into rural areas.

• Structural Monitoring and Maintenance
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• 제9권4호
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• pp.305-321
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• 2022

Bridge structural health monitoring with the aim of continuously assessing structural safety and reliability represents a topic of major importance for worldwide infrastructure managers. In the last two decades, due to their potential economic and operational advantages, drive-by approaches experienced growing consideration from researcher and engineers. This work addresses two technical topics regarding indirect frequency estimation methods: bridge and vehicle dynamics overlapping, and bridge expansion joints impact. The experimental campaign was conducted on a mixed multi-span bridge located in Lombardy using a Ford Galaxy instrumented with a mesh of wireless accelerometers. The onboard time series were acquired for a number of 10 passages over the bridge,performed at a travelling speed of 30 km/h, with no limitations imposed to traffic. Exploiting an ad-hoc sensors positioning, pitch vehicle motion was compensated, allowing to estimate the first two bridge bending frequencies from PSD functions; moreover, the herein adopted approach proved to be insensitive to joints disturbance. Conclusively, a sensitivity study has been conducted to trace the relationship between estimation accuracy and number of trips considered in the analysis. Promising results were found, pointing out a clear positive correlation especially for the first bending frequency.

• Environmental Engineering Research
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• 제24권2호
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• pp.220-237
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• 2019

Solid waste management (SWM) is one of the poorly rendered services in developing countries - limited resources, increasing population, rapid urbanization and application of outdated systems leads to inefficiency. Lack of proper planning and inadequate data regarding solid waste generation and collection compound the SWM problem. Decision makers need to formulate solutions that consider multiple goals and strategies. Given the large number of available options for SWM and the inter-relationships among these options, identifying SWM strategies that satisfy economic or environmental objectives is a complex task. The paper develops a mathematical model for a municipal Integrated SWM system, taking into account waste generation rates, composition, transportation modes, processing techniques, revenues from waste processing, simulating waste management as closely as possible. The constraints include those linking waste flows and mass balance, processing plants capacity, landfill capacity, transport vehicle capacity and number of trips. The linear programming model integrating different functional elements was solved by LINGO optimization software and various possible waste management options were considered during analysis. The model thus serves as decision support tool to evaluate various waste management alternatives and obtain the least-cost combination of technologies for handling, treatment and disposal of solid waste.

• 대한인간공학회지
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• 제28권1호
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• pp.37-51
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• 2009

The nuclear power industry in the world has recognized the importance of integrating non-technical and team skills training with the technical training given to its control room operators to reduce human errors since the Three Mile Island and Chernobyl accidents. The Nuclear power plant (NPP) industry in Korea has been also making efforts to reduce the human errors which largely have contributed to 120 nuclear reactor trips from the year 2001 to 2006. The Crew Resource Management (CRM) training was one of the efforts to reduce the human errors in the nuclear power industry. The CRM was developed as a response to new insights into the causes of aircraft accidents which followed from the introduction of flight recorders and cockpit voice recorders into modern jet aircraft. The CRM first became widely used in the commercial airline industry, but military aviation, shipboard crews, medical and surgical teams, offshore oil crews, and other high-consequence, high-risk, time-critical industry teams soon followed. This study aims to develop a CRM training program that helps to improve plant performance by reducing the number of reactor trips caused by the operators' errors in Korean NPP. The program is; firstly, based on the work we conducted to develop a human factors training from the applications to the Nuclear Power Plant; secondly, based on a number of guidelines from the current practicable literature; thirdly, focused on team skills, such as leadership, situational awareness, teamwork, and communication, which have been widely known to be critical for improving the operational performance and reducing human errors in Korean NPPs; lastly, similar to the event-based training approach that many researchers have applied in other domains: aircraft, medical operations, railroads, and offshore oilrigs. We conducted an experiment to test effectiveness of the CRM training program in a condition of simulated control room also. We found that the program made the operators' attitudes and behaviors be improved positively from the experimental results. The more implications of the finding were discussed further in detail.

• 복식
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• 제56권7호
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• pp.142-151
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• 2006

Bikini, a brief two-piece bathing suit revealing the wearer's navel, was first introduced in Paris, in 1946. However, it was not until the late 1950s that Americans were ready to adopt bikinis. Therefore, I focused on the following research questions to understand the popularization process of bikinis in the United States, from 1946 to the 1960s: 1. Why were Americans initially hesitant to adopt the bikini? 2. What were the factors that influenced the popularization of the bikini among Americans in the late 1950s? Primary sources including Bazaar. Madmoiselle, Vogue, The New York Times, and Life were reviewed. I referred to secondary sources on the history of fashion and American popular culture to interpret primary sources. According to the primary sources, Americans were hesitant to adopt the bikini, partly due to the excessive demand on the wearer's figure. However, the conservative social atmosphere during Cold War would not accept immorality and obscenity which would threaten America's future. Therefore, the campaigns against the sex industry, which developed prominently after WWII, predominated American society during the 1950s. Under this atmosphere, a small number of pictures and articles on bikinis appeared in the primary sources. Bikinis were only found in advertisements including sun lotions and hair removers. However, American society had to accept the change in sexual mores by the end of the 1930s. Body-revealing fashions including miniskirts, hot pants, and see-through material reflected the change in social convention. By the end of the 1950s, the number of pictures and articles on bikinis also began to increase in the primary sources. More Americans adopted bikinis with the increasing number of private pools and European trips. The vogue of sun-tanning and movies featuring bikinis further contributed to their popularity in the late 1930s and into the 1960s.

• 산업경영시스템학회지
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• 제42권1호
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• pp.8-20
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• 2019

The vehicle routing problem is one of the vibrant research problems for half a century. Many studies have extensively studied the vehicle routing problem in order to deal with practical decision-making issues in logistics. However, developments of new logistics strategies have inevitably required investigations on solution methods for solving the problem because of computational complexity and inherent constraints in the problem. For this reason, this paper suggests a simulated annealing (SA) algorithm for a variant of vehicle routing problem introduced by a previous study. The vehicle routing problem is a multi-depot and multi-trip vehicle routing problem with multiple heterogeneous vehicles restricted by the maximum permitted weight and the number of compartments. The SA algorithm generates an initial solution through a greedy-type algorithm and improves it using an enhanced SA procedure with three local search methods. A series of computational experiments are performed to evaluate the performance of the heuristic and several managerial findings are further discussed through scenario analyses. Experiment results show that the proposed SA algorithm can obtain good solutions within a reasonable computation time and scenario analyses show that a transportation system visiting non-dedicated factories shows better performance in truck management in terms of the numbers of vehicles used and trips for serving customer orders than another system visiting only dedicated factories.

• 한국안전학회지
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• 제35권5호
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• pp.115-120
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• 2020

From 2009 when the CNS facility was installed, the number of reactor failures due to abnormal CNS facility system has increased significantly. Of the total of 19 nuclear reactor shutdowns over the six years from 2009 to 2019, there were 10 nuclear reactor shutdowns associated with the CNS facility, which are very numerous. Therefore, this report intends to analyze the history of nuclear reactor shutdowns due to CNS facility system failure in detail, and to present the root cause and solution to problems. As a result of FMEA implementation of CNS facility system, a total of 76 SPVs were selected. In addition, 10 cases of reactor shutdown history due to CNS facility system abnormalities were analyzed in detailed, and improvement plans for solving the root cause and problem were suggested for each trip history. The results of this study are expected to be able to operate the domestic research reactor and CNS facilities more stably by providing effective measures to prevent recurrence of CNS facilities and reactor trips.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.235-241
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• 1995

YGN 3 and 4 are the nuclear power plants having System 80 characteristics with a rated thermal output of 2815 MWth and a nominal net electrical output of 1040 MWe. YGN 3 achieved commercial operation on March 31, 1995 and YGN 4 completed Power Ascension Test (PAT) at 20%, 50%, 80% and 100% power by September 23, 1995. YGN 3 and 4 design incorporates the Reactor Power Cutback System (RPCS) which reduces plant trips caused by Loss of Load (LOL)/Turbine Trip and Loss of One Main Feedwater Pump (LOMFWP). The key design objective of the RPCS is to improve overall plant availability and performance, while minimizing challenges to the plant safety systems. The RPCS is designed to rapidly reduce reactor power by dropping preselected Control Element Assemblies (CEAs) while other NSSS control systems maintain process parameters within acceptable ranges. Extensive RPCS related tests performed during the initial startup of YGN 4 demonstrated that the RPCS can maintain the reactor on-line without opening primary or secondary safety valves and without actuating the Engineered Safety Features Actuation System (ESFAS). It is expected that use of the RPCS at YGN will increase the overall availability of the units and reduce the number of challenges to plant safety systems.

• 대한교통학회지
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• 제30권6호
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• pp.47-57
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• 2012

본 연구는 지역적 범위에 따른 화물자동차의 공차통행 발생요인을 검토함으로써, 기존 화물수요모형의 한계를 제시하고자 하였다. 지역간 및 대도시 화물자동차의 공차통행 발생요인을 검토하기 위하여 화물자동차 속성, 출발지 및 도착지 특성, 그리고 운송품목의 유형을 고려한 서열로짓모형을 추정하였으며, 이를 통하여 화물자동차의 공차통행 발생에 영향을 미치는 다양한 요인들을 정량적으로 검토하였다. 분석결과 지역간 화물자동차의 공차통행 발생요인과 대도시 화물자동차의 공차통행 발생요인은 서로 상이한 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제88권4호
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• pp.323-334
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• 2023

The submerged floating tunnel (SFT) infrastructure has been regarded as an emerging technology that efficiently and safely connects land and islands. The SFT route problem is an essential part of the SFT planning and design phase, with significant impacts on the surrounding environment. This study aims to develop an optimization model considering transportation and structure factors. The SFT routing problem was optimized based on two objective functions, i.e., minimizing total travel time and cumulative strains, using NSGA-II. The proposed model was applied to the section from Mokpo to Jeju Island using road network and wave observation data. As a result of the proposed model, a Pareto optimum curve was obtained, showing a negative correlation between the total travel time and cumulative strain. Based on the inflection points on the Pareto optimum curve, four optimal SFT routes were selected and compared to identify the pros and cons. The travel time savings of the four selected alternatives were estimated to range from 9.9% to 10.5% compared to the non-implemented scenario. In terms of demand, there was a substantial shift in the number of travel and freight trips from airways to railways and roadways. Cumulative strain, calculated based on SFT distance, support structure, and wave energy, was found to be low when the route passed through small islands. The proposed model helps decision-making in the planning and design phases of SFT projects, ultimately contributing to the progress of a safe, efficient, and sustainable SFT infrastructure.