• 대한안전경영과학회지
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• 제11권1호
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• pp.1-6
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• 2009

The specific feature of trains as a means of transportation is that, on one side, at once they can carry big loads but, at the same time, if an accident occurs, it potentially leads to many human casualties or big material losses. Especially, train accidents caused by bad weather conditions result in many fatal losses of human lives and property. In Korea many railways run either in mountainous areas or along rivers thus making them especially susceptible to natural hazards. The types of damages inflicted by heavy rains resulting from rapidly changing meteorological conditions are diverse; and not only their scope is big but also they repeat regularly. Consequently, this study analyses the reasons why such effects of heavy rains on the railway conditions, damage to the railways caused by heavy rains or cases of stone fall as well as other types of accidents are not avoided. Study also, on the basis of laws related to movement in poor weather conditions and specifics of train braking, identifies systematic and technical problems and suggests and emphasizes new complex measures on their prevention.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1185-1192
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• 2004

Recently heavy traffic is getting worse because increasing population of transportation in urban area. In order to solve this problem. subway is realized with high speed, high density, highly efficiency. When fire accident happened in Dae-Gu subway in February 2003, there happened loss of people and lots of damage because of not being able to control even though fire alarm which was set up in the station rang. This thesis has constructed a simulation integrating operation system using a Database construction, operating program analysis in order to build up the most efficient train operation system. The result of simulation integrating operation system with emergency virtual situation like station and train fire, train failure, power line failure, all trains running on the rail were secured safety by train operation control system. With integrating operation of each train control system, train system, power system, machine facility system, the most efficient integrating operation system should have been constructed at the time the subway fire and power failure broke out.

• Industrial Engineering and Management Systems
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• 제14권4호
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• pp.347-371
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• 2015

A hybrid procedure based on multi-Criteria Satisfaction Analysis (MUSA) and a Network Data Envelopment Analysis (NDEA) is proposed to evaluate the relative efficiency of customer services in bank branches. First, a three-stage process including sub-processes such as customer expectations, customer satisfaction, and customer loyalty, is defined to model the banking customer services. Then, fulfillment of customer expectations, customer loyalty level, and the customer satisfaction degree are measured and quantified through a multi-dimensional questionnaire based on customers' perceptions analysis and MUSA method, respectively. The customer services scores and the other criteria such as mean of employee evaluation score, operation costs, assets, deposits, loans, number of accounts are considered in network three-stage DEA model. The proposed NDEA model is formed based on multipliers perspective, output-oriented, and constant return to scale assumptions. The proposed NDEA model quantifies and assesses the total efficiency of main process and assigns the efficiency to customer expectations, customer satisfactions, and customer loyalties sub-processes in bank branches. The whole procedure is applied on 30 bank branches in IRAN. The proposed approach can be used in other organizations such as airports, airline agencies, urban transportation systems, railway organizations, chain stores, chain restaurants, public libraries, and entertainment centers.

• 한국기계가공학회지
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• 제12권6호
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• pp.45-51
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• 2013

Friction stir welding using aluminum alloys has been widely applied for transportation vehicles because of the light specific weight, which can be used to obtain sound joint and high mechanical properties. This study shows the effects of rotation speed, welding speed, welding load, and tool shape on defect formation with extruded AA6005, which is used for railway vehicle structures of non-uniform thickness welded by friction stir welding using load control systems. Optical microscopy observations and liquid penetrant testing of each FSW joint were carried out in order to observe defect formation. Two kinds of defects, that of probe wear and that of lack of penetration in the bottom of the welded zone, were observed. In the case of using a taper shaped tool, the defect free zone is very narrow, within 100 kgf; however, in case of using a cylindrical shape tool, the defect free zone is wider.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.310-315
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• 2006

In several years, the geographic information system has been being applied into various departments, i.e. estate, transportation, prevention against disasters, agriculture, environment, etc. Especially, it is very useful for us to manage the infrastructures of urban transit which are scattered and located in the vast areas of city. But, in the 2D geographic information system, it is impossible to manage the various inner facilities of stations which are in the same spatial location on GIS. Then, the 3D station management system has been developed for the efficient management of station facilities in urban transit. Through this system, from the virtual cyberspace of station on PC, we can move and go to any places of station we want without going to the station fields. So, we can manage the various information of location information, basis information, maintenance information about the inner facilities such as architectural structures, machinery facilities, electronic equipments. And, this system is also connected with the drawings and technical documents in each facilities. So, we're sure, this system will improve the efficiency of maintenance work and information management of stations.

• KIEAE Journal
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• 제9권1호
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• pp.99-106
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• 2009

This study aims to survey the acoustical environment in the region around airport where there are various transportation noises such as aircraft noise, railway noise and traffic noise, and to analyze the subjective response on the noise to the people who live in house or work in office nearby airport. Measurement and subjective response evaluation were carried out at the same time and outdoor noise level was measured all day long to calculate one day results such as average Leq or one day WECPNL etc. The results showed that the military aircraft produces very high level comparing with commercial aircraft, for instance the sound level of commercial outdoor was lower than that of military aircraft indoor. Double and triple window were more effective for controlling the noise than single window, which showed the possibility of sound insulation treatment by installing windows having higher sound insulation performance. Finally the subjective response was resulted that the most annoying noise is from aircraft and counterplan they hope is 'airport moving out'. Leq 65 dB(A), the criteria value of sound insulation treatment, was corresponding to the subjective response of median annoyance '4' out of 7th scale.

• 한국안전학회지
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• 제29권4호
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• pp.191-198
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• 2014

In the event of continued train operation being impossible as the result of a breakdown, it will be essential to dispatch a relief train to recover the broken down train. Operation of relief train carries with the risk of collision in the process of connection with broken down train. The present study looks at the suitability of risk management procedures and associated problems in the light of case studies of relief train operation, and of national legal standards and railroad company regulations. It looks at appropriate methods of risk management and the problems that can arise. Based on the study a method is proposed of operating the relief train which is consistent with appropriate risk management. The proposed method will improve the safety of relief train operation, It is hoped that the results of the study will be reflected in relevant laws and operating company regulations, and so contribute to enhancing the overall level of railroad safety.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1652-1655
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• 2008

Indoor air quality (IAQ) of subway becomes a key issue as the IAQ guidelines for public transportation published. There are two major sources regarding IAQ of subway; One is the sources coming from outdoor air and the other is sources of inside. Particulate matters smaller than 10 micrometer (PM10) and carbon dioxide ($CO_2$) are recognized as the one of the most severe pollutants in Korea. The source of PM10 is mainly coming from outdoor air, however, the source of $CO_2$ is coming from passengers exhaust. According to the guidelines, the level of $CO_2$ should be lower than 2500ppm for normal operating time and lower than 3500ppm for rush hour. In order to satisfy these guidelines, the volume of mechanical ventilation should be increase which consumes extra energy for heating or cooling. Therefore, the optimum volume of mechanical ventilation should be calculated for energy saving. In this study, we measured the natural ventilation rate by door-opening which can reduce the load of mechanical ventilation. The $CO_2$ generator and sensors were used to measure the change of $CO_2$ by periodic door-opening of subway.

• Safety and Health at Work
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• 제12권1호
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• pp.42-50
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• 2021

Introduction: Despite huge investments in new technology and transportation infrastructure, terrible accidents still remain a reality of traffic. Methods: Severe traffic accidents were analyzed from four prevailing modes of today's transportations: sea, air, railway, and road. Main root causes of all four accidents were defined with implementation of the approach, based on Flanagan's critical incident technique. In accordance with Molan's Availability Humanization model (AH model), possible preventive or humanization interventions were defined with the focus on technology, environment, organization, and human factors. Results: According to our analyses, there are significant similarities between accidents. Root causes of accidents, human behavioral patterns, and possible humanization measures were presented with rooted graphs. It is possible to create a generalized model graph, which is similar to rooted graphs, for identification of possible humanization measures, intended to prevent similar accidents in the future. Majority of proposed humanization interventions are focused on organization. Organizational interventions are effective in assurance of adequate and safe behavior. Conclusions: Formalization of root cause analysis with rooted graphs in a model offers possibility for implementation of presented methods in analysis of particular events. Implementation of proposed humanization measures in a particular analyzed situation is the basis for creation of safety culture.

• 한국가시화정보학회지
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• 제19권2호
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• pp.26-31
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• 2021

The spanwise growth of turbulence structures in turbulent pipe flow was investigated using the direct numerical simulation data of Re_𝜏 = 544, 934 and 3008. Two-point correlations and pre-multiplied energy spectra of streamwise velocity fluctuations were examined along the spanwise direction. The arclength direction is defined as r𝛳, which is useful for an analogy with the spanwise direction for channels or boundary layers; here, r and 𝛳 are the radial distance from the core and the azimuthal angles, respectively. Both analyses showed that the arclength scales increased with increasing the wall-normal distance. It showed that the coherent structures were confined in the core region due to the crowding effect of a circular pipe geometry. The pipe flow simulation could describe a realistic geometrical flow along the azimuthal direction, unlike the simulations of turbulent channel or boundary layer flow using periodic boundary conditions along the spanwise direction. The present results provided the spanwise organization of energy-containing motions over a broad range of scales in turbulent pipe flow.