• Title/Summary/Keyword: Facility critical path

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A Study of Transfer Impedance of KTX and Rail Stations (KTX역사 및 일반철도역사의 환승저항 산정)

  • Kim, Hye-Ran;Kim, Hwang-Bae;O, Jae-Hak;Choe, Jin-Hui
    • Journal of Korean Society of Transportation
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    • v.27 no.5
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    • pp.189-194
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    • 2009
  • Transfer impedance is one of the most critical factors decreasing the competitive power of public transportation. Therefore, it is necessary to improve transfer impedance of KTX and rail station users in order to increase the usage of public transportation. Important factors influencing transfer decisions include exterior walking distance, interior walking distance, steps, and escalators. However, their comparative impedances are different. This study constructed a model for calculating transfer impedance based on bodily sensational transfer time in KTX and rail stations and calculated transfer impedance on major KTX and rail stations in Korea. The study results show that the addition of one escalator decreases travel time by one to three minutes. The calculated transfer impedance based on bodily sensational transfer time in this study can be utilized as objective criteria to compare transfer conditions of different KTX and rail stations and to prioritize them for facility improvement. The calculated transfer impedance also can be used as facility guidelines for designing a new transit center.

Physical protection system vulnerability assessment of a small nuclear research reactor due to TNT-shaped charge impact on its reinforced concrete wall

  • Moo, Jee Hoon;Chirayath, Sunil S.;Cho, Sung Gook
    • Nuclear Engineering and Technology
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    • v.54 no.6
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    • pp.2135-2146
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    • 2022
  • A nuclear energy facility is one of the most critical facilities to be safely protected during and after operation because the physical destruction of its barriers by an external attack could release radioactivity into the environment and can cause harmful effects. The barrier walls of nuclear energy facilities should be sufficiently robust to protect essential facilities from external attack or sabotage. Physical protection system (PPS) vulnerability assessment of a typical small nuclear research reactor was carried out by simulating an external attack with a tri-nitro toluene (TNT) shaped charge and results are presented. The reinforced concrete (RC) barrier wall of the research reactor located at a distance of 50 m from a TNT-shaped charge was the target of external attack. For the purpose of the impact assessment of the RC barrier wall, a finite element method (FEM) is utilized to simulate the destruction condition. The study results showed that a hole-size of diameter 342 mm at the front side and 364 mm at the back side was created on the RC barrier wall as a result of a 143.35 kg TNT-shaped charge. This aperture would be large enough to let at least one person can pass through at a time. For the purpose of the PPS vulnerability assessment, an Estimate of Adversary Sequence Interruption (EASI) model was used, which enabled the determination of most vulnerable path to the target with a probability of interruption equal to 0.43. The study showed that the RC barrier wall is vulnerable to a TNT-shaped charge impact, which could in turn reduce the effectiveness of the PPS.

A Study on Operation Strategy by Multi-variate Regression of Deagu Arboretum Visitor's Satisfaction (대구수목원 이용객 만족모델을 통한 운영 방안 연구)

  • Kang, Kee-Rae
    • Journal of Korean Society of Forest Science
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    • v.101 no.1
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    • pp.36-45
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    • 2012
  • Education on the environment and plants offered by arboretum for today's people not only contribute to foster a better natural environment in urban region but also provide visitors with decent refreshment environment and beyond. In the study, the author undertook the observation on usage behavior and satisfaction model of arboretum visitors expect and investigated the facilities and programs to be offered by arboretum in order to propose the opinion regarding the service. For observation size of variables in a multiple regression analysis of variables is influencing satisfaction rankings walks the line of flow, the educational effect on the environment, cleanliness of the facility, visits pay, natural beauty, diversity of trees, accessibility and friendliness of staff, expansion of facilities in the arboretum and appeared as a complement. In case of visitor attribute, the residents living near the facility showed the highest visit frequency of more than 5 times, especially as part of taking a walk. This proves that the visit to arboretum is considered as part of everyday life, and thus a new program and walk path as well as movement route are needed to be developed for the visitors. In the question relating to the facilities and operation programs in Daegu Arboretum, particularly the requests by visitors, they responded that the establishment of cultural event, beautiful natural scenery, refreshment and convenience facilities is the most critical issue. In addition, the management on withered trees and bare lands is an urgent issue as well. In this sense, the Operation and Management Strategies based upon the visitor behaviors and model of satisfaction are needed to deal with the adoption of diverse events and festivals joined by local residents, ombudsman program, environmental program development for students and teachers within the region, negligent bare lands and withered tree replacement, and cafeteria facility improvement and supplement as well as the bench marking of other facilities than arboretums located in other regions. These items are thought to be sufficiently dealt with by Daegu Arboretum having no more external resources. It is recognized that the visitor satisfaction begins from a minor thing, and a small difference determines a great satisfaction, and thus the software approach rather than hardware one is in need.

Development of Intelligent ATP System Using Genetic Algorithm (유전 알고리듬을 적용한 지능형 ATP 시스템 개발)

  • Kim, Tai-Young
    • Journal of Intelligence and Information Systems
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    • v.16 no.4
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    • pp.131-145
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    • 2010
  • The framework for making a coordinated decision for large-scale facilities has become an important issue in supply chain(SC) management research. The competitive business environment requires companies to continuously search for the ways to achieve high efficiency and lower operational costs. In the areas of production/distribution planning, many researchers and practitioners have developedand evaluated the deterministic models to coordinate important and interrelated logistic decisions such as capacity management, inventory allocation, and vehicle routing. They initially have investigated the various process of SC separately and later become more interested in such problems encompassing the whole SC system. The accurate quotation of ATP(Available-To-Promise) plays a very important role in enhancing customer satisfaction and fill rate maximization. The complexity for intelligent manufacturing system, which includes all the linkages among procurement, production, and distribution, makes the accurate quotation of ATP be a quite difficult job. In addition to, many researchers assumed ATP model with integer time. However, in industry practices, integer times are very rare and the model developed using integer times is therefore approximating the real system. Various alternative models for an ATP system with time lags have been developed and evaluated. In most cases, these models have assumed that the time lags are integer multiples of a unit time grid. However, integer time lags are very rare in practices, and therefore models developed using integer time lags only approximate real systems. The differences occurring by this approximation frequently result in significant accuracy degradations. To introduce the ATP model with time lags, we first introduce the dynamic production function. Hackman and Leachman's dynamic production function in initiated research directly related to the topic of this paper. They propose a modeling framework for a system with non-integer time lags and show how to apply the framework to a variety of systems including continues time series, manufacturing resource planning and critical path method. Their formulation requires no additional variables or constraints and is capable of representing real world systems more accurately. Previously, to cope with non-integer time lags, they usually model a concerned system either by rounding lags to the nearest integers or by subdividing the time grid to make the lags become integer multiples of the grid. But each approach has a critical weakness: the first approach underestimates, potentially leading to infeasibilities or overestimates lead times, potentially resulting in excessive work-inprocesses. The second approach drastically inflates the problem size. We consider an optimized ATP system with non-integer time lag in supply chain management. We focus on a worldwide headquarter, distribution centers, and manufacturing facilities are globally networked. We develop a mixed integer programming(MIP) model for ATP process, which has the definition of required data flow. The illustrative ATP module shows the proposed system is largely affected inSCM. The system we are concerned is composed of a multiple production facility with multiple products, multiple distribution centers and multiple customers. For the system, we consider an ATP scheduling and capacity allocationproblem. In this study, we proposed the model for the ATP system in SCM using the dynamic production function considering the non-integer time lags. The model is developed under the framework suitable for the non-integer lags and, therefore, is more accurate than the models we usually encounter. We developed intelligent ATP System for this model using genetic algorithm. We focus on a capacitated production planning and capacity allocation problem, develop a mixed integer programming model, and propose an efficient heuristic procedure using an evolutionary system to solve it efficiently. This method makes it possible for the population to reach the approximate solution easily. Moreover, we designed and utilized a representation scheme that allows the proposed models to represent real variables. The proposed regeneration procedures, which evaluate each infeasible chromosome, makes the solutions converge to the optimum quickly.

Task Satisfaction, Job Satisfaction, Organizational Commitment, and Turnover Intension of Center for Children's Foodservice Management Employees (어린이급식관리지원센터 직원의 업무만족, 직무만족, 조직몰입 및 이직의도)

  • Park, Eun Hye;Lee, Young Eun
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.44 no.12
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    • pp.1881-1894
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    • 2015
  • The objective of this study was to provide information on difficulty of performing tasks, degree of task satisfaction, job satisfaction, organizational commitment, and turnover intention as well as investigate correlations among these factors. Data were collected on employees working at Centers for Children's Foodservice Management, which had been operating for over 6 months until December 2013. The recruitment period was from December 16, 2013 to January 30, 2014. A total of 228 employees (79.7%) participated in the study, and 227 completed questionnaires were analyzed. Statistical analyses were performed on the data utilizing the SPSS V20.0 and AMOS V21.0 programs. The main results of this study were as follows: task satisfaction of employees in charge of 'visiting-teaching' for children was highest (4.24 points), whereas that of employees in charge of financial management was lowest (2.92 points). In terms of evaluation of job satisfaction factors, the score of 'co-worker' was highest (3.99 points) while that of 'payment' was lowest (2.45 points). Average scores of general job satisfaction, organizational commitment, and turnover intention were 3.56 points, 3.54 points, and 3.07 points, respectively. Job achievement was the most significant influencing factor on general job satisfaction, organizational commitment, and turnover intention. According to the path analysis results, the degree of task satisfaction affected job satisfaction. Organizational commitment had a more significant effect on turnover intention than job satisfaction and mediate both job satisfaction and turnover intention. Although employees of CCFSMs endeavor to improve the quality of child-care facility foodservice, some facilities do not. Controlling turnover intention of employees is especially critical for CCFSMs since it is important for each employees to form strong bonds with child-care facilities as well as to shorten the time required to train new employees. Thus, job satisfaction, which is related to organizational commitment and turnover intention, can be improved by considering poorly scored job satisfaction factors such as wage or workload.