• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.10-23
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• 2016

With requiring circumspections using big data, this study attempts to develop and apply the search method for audit issues relating to the ITS policy or program. For the foregoing, the auditing process of the board of audit and inspection was converged with the theoretical frame of boundary analysis proposed by William Dunn as an analysis tool for audit issues. Moreover, we apply the text mining technique in order to computerize the analysis tool, which is similar to the boundary analysis in the concept of approaching meta-problems. For the text mining analysis, specific model we applied the antisymmetry-symmetry compound lexeme-based LDA model based on the Latent Dirichlet Allocation(LDA) methodologies proposed by David Blei. The several prime issues were founded through a case analysis as follows: lack of collection of traffic information by the urban traffic information system, which is operated by the National Police Agency, the overlapping problems between the Ministry of Land, Infrastructure and Transport and the Advanced Traffic Management System and fabrication of the mileage on digital tachograph.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.609-617
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• 2017

Railways are one of the safest and most important transportation systems in the world. On the other hand, due to the increasing complexity of the railway system and the running distance of rail vehicles, railway accidents occur continuously every year. In particular, in the case of high-speed trains and freight trains, if the function of the axle bearing is lost due to abnormal overheating of the axle box bearing, the load on the axle becomes uneven. Therefore, abnormal overheating in the train axle box bearings can cause serious accidents or derailments. For this purpose, a Hot Box Detector (HBD) was installed in the track side of a high speed line to detect abnormal overheating. This paper proposes an EWMA technique-based axle temperature monitoring method to detect abnormal overheating quickly and efficiently. A statistical design of the proposed method was also performed. The proposed method has better performance compared to the current method in the case of abnormal overheating and the performance is improved by approximately 170% at the maximum.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.457-465
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• 2009

Lithium batteries are widely used in mobile electronic devices due to their higher voltage and energy density, lighter weight and longer life cycle compared to other secondary batteries. In particular, high demand for lithium batteries is expected for electric cars. In case of lithium batteries used in electric cars, driving distance must be calculated accurately and discharging should not be done below the level of making it impossible to crank. Therefore, accurate information about state of charge (SOC) becomes an essential element for reliable driving. In this paper, a new method of estimating the SOC of lithium polymer batteries by using AC impedance is proposed. In the proposed method, parameters are extracted by fitting a curve of impedance measured at each frequency on the equivalent impedance model and extracted parameters are used to estimate SOC. Experiments were conducted on lithium polymer batteries with similar capacities made by different manufacturers to prove the validity of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.5
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• pp.503-508
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• 2012

Recently green house gas emission problem has been issued because $CO_2$ emission is known to cause global warming. Hence, introduces more stringent emission and fuel economy requirements in various countries, including Korea. In this research, $CO_2$ emission factor characteristics of in-use cars, which are the most dominant vehicle type in Korea, were studied, and 129 gasoline vehicles, 100 diesel vehicles, and 34 LPG vehicles were tested on a chassis dynamometer. In the tests, CO and $CO_2$ emissions as well as fuel reduction rates weremeasured. The tests were conducted in the CVS-75 mode, which has been considered for developing emission factors for regulating emissions from light-duty vehicles in Korea. Through experiments, correlations among displacement, fuel consumption efficiency, fuel type, mileage, driving pattern, and $CO_2$ emission were investigated.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.101-108
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• 2012

This study deals with the traffic accidents of circular intersections in Korea. The goal of this study is to develop the traffic accident models using ZAM. The main results are as follows. First, in the case of 'violating the operational method of intersection', ZINB(zero-inflatednegative binomial) models were analyzed to be the best fit to the data. Second, in the case of' no maintaining the safe distance', ZINB models were also analyzed to be the best fit to the data. Finally, such the common variables as traffic volume and width of circular roadway were selected as the independent variables. The more traffic volume and the less width of circulatory roadway were evaluated to make the more accidents. Such the specific variables as the number of approach lanes and speed reduction facilities were selected as the explanatory variables. The more approach lanes and the less speed reduction facilities were evaluated to give the more accidents. This study might be expected to give some implications to the accident research on the circular intersections.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.421-426
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• 2004

Increasing of the multinational corporation brought into the international multimodal Increasing of the multinational corporation brought into the international multimodal transport on the logistics environment. In case of Europe which have a great infrastructure, they are tried to develope a second of the silk road constantly. This paper emphasized the importance of international multimodal transport and proposed the model for northeast multimodal transport. For this research, we analyzed the multimodal transport system in Europe and north corridor of TAR. We are expecting economic effect of the route is including republic of korea and developed a model for connecting with sea, air and road. Actually, this research can not be enough data of numerical value for proving this effectiveness. but we developed and proposed a specific route of multimodal transport that was never suggested. Consequently, we established basic ground for comparing each transport route in the future research.

• The KIPS Transactions:PartC
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• v.17C no.2
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• pp.181-189
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• 2010

HAP(High Altitude Platform) is a stationary aerial platform positioned in the stratosphere between 17Km and 22Km height and it could act as an MBS (Mobile Base Station). HAP based Network has advantages of both satellite system and terrestrial communication system. In this paper we study the deploy of multiple HAP MBS that can provides efficient communication for users. For this study, EM(Expectation Maximization) clustering algorithm is used to cluster terrestrial mobile nodes. The object of this paper is improving EM algorithm into the clustering algorithm for efficiency in variety aspects considering distance between mobile terminal units and speed of mobile terminal units, and estimating performance of HAP MBS deploy technique with use of improved EM algorithm using RWP (Random Waypoint) node mobility.

• Journal of Korean Society of Transportation
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• v.25 no.3
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• pp.145-154
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• 2007

Determining stop spacing is a very important process in transit system planning. This study is involved in an analytical approach to decide the transit stop spacing. Transit stop spacing should be longer as 1) user access speed, 2) user travel time, and 3) dwell time increase, and shorter as 1) passengers (boardings and alightings) and 2) headway increase. In this study, a methodology is proposed to determine transit stop spacing to minimize total cost (user cost plus operator cost) with irregular passenger distribution (boardings and alightings) Without considering in-vehicle passengers, the transit stop spacing should be shorter in the concentrated sections of the passenger distribution than in others to minimize total cost. Through the conceptual analysis, it is verified that the transit stop spacing could be longer as the in-vehicle passengers increase in certain sections. This study proposes a simple practical method to determine transit stop spacing and locations instead of a dynamic programming method which generally includes a complex and difficult calculation. If the space axis is changed to a time axis. the methodology of this study could be expanded to analyze a solution for the transit service (or headway) schedule problem.

• Journal of Korean Society of Transportation
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• v.30 no.2
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• pp.29-42
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• 2012

Recently, traffic congestion has become serious due to increase of private car usages. Carsharing or other innovative public transportation systems were developed to alleviate traffic congestion and carbon emissions. These measures can make the traffic environment more comfortable, and efficient. Cloud Transportation System (CTS) is a recent carsharing model. User can rent an electronic vehicles with various traffic information through the CTS. In this study, a concept, vision and scenarios of CTS are introduced. And, authors analyzed the location of CTS rental stations and estimated CTS demands. Firstly, we analyze the number of the population, employees, students and traffic volume in study areas. Secondly, the frequency and utilization time are examined. Demand for CTS in each traffic zone was estimated. Lastly, the CTS rental station location is determined based on the analyzed data of the study areas. Evaluation standard of the determined location includes accessibility and density of population. And, the number of vehicles and that of parking zone at the rental station are estimated. The result suggests that Haewoondae Square parking lot would be assigned 11 vehicles and 14.23 parking spaces and that Dongbac parking lot be assigned 7.9 vehicles and 10.29 parking spaces. Further study requires additional real-time data for CTS to increase accuracy of the demand estimation. And network design would be developed for redistribution of vehicles.

• Journal of Korean Society of Transportation
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• v.15 no.3
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• pp.75-92
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• 1997

추월가능성을 판단하기 위해서 앞을 바라볼 수 있어야 하는 거리를 추월시거라 한다. 적절한 추원시거의 확보는 2차선 도로의 효율성과 운전자의 안전성 제고 및 도로설계시 매우 중요하다. 이러한 목적을 위하여 추월시거를 산정할 수 있는 여러 모형이 개발되었으나, 실제 교통상황을 반영하기에 많은 문제점을 안고 있음이 지적되고 있다. 따라서 본 논문은 기존 모형들의 이론적 배경을 고찰하고, 각 모형의 단점과 한계를 파악하여, 운전자의 실제 추월형태를 고려한 새로운 추월시거산정모형을 개발하는데 주안점을 두고 있다. 본 논문에서 개발한 PASS모형은 현재 미국에서 도로설계시 기준으로 사용되고 있는 AASHTO모형을 보완하여 구축하였다. 기존의 모형들은 서로 다른 조건을 가정하여 개발되었기 때문에 각 모형들의 추월시거 산정값을 비교분석하는데 어려움이 있다. 하지만 PASS모형은 운전자의 반응시간, 차량의 길이, 차량의 가속능력 등 실제 추월시거 산정시 반드시 고려해야 할 중요한 요소들을 특성치로 반영할 수 있게 함으로써 다양한 추월 상황과 현실적인 교통상황을 폭넓게 수용할 수 있는 장점을 갖고 있다. 본 논문에서는 새로 개발한 P SS모형을 이용하여 얻은 결과와 기존의 AASHTO모형, MUTCD모형, Glennon모형을 통해 얻은 결과를 비교하였으며, PASS모형에 우리나라 현실에 적합한 특성치를 적용하여 2차로 도로의 추월시거를 산정하였다. 이 결과 현재 우리나라 도로용량편람에서 제시하고 있는 추월기능구간 기준인 450m가 설계속도가 낮은 일반국도에는 타당함을 확인할수 있었다. 그러나, 설계속도가 높은 화물타의 운행빈도가 높은 고속국도의 경우, 재검토가 필요할 것으로 판단된다.기존의 광유계 윤활제에 비하여 대단히 고가하는 문제점을 갖고 있다. 그러나 윤활 마찰면의 다양화와 가혹한 사용조건은 자성유체 윤활제의 연구개발 필요성을 크게 증대시키고 있다.xed Effects Model)을 결정하고, 각각에 해당하는 통계모형을 구축하였다. 이 결과 (1) 업종 및 기업규모별로 그룹간에 유의한 특성이 발견되었으며, (2) R&D 및 광고투자는 기업의 시장성과를 설명하는 중요한 변수이나, (3) R&D 투자의 경우는 광고에 비해 불확실성이 존재하는 것으로 나타났고, (4) 수리모형에서 도출된 한계원리가 통계모형에서도 유효한 것으로 드러났다.등을 토대로 한 10대 산업을 육성하기 위하여 과학기술부는 기술수요조사를 바탕으로 49개 주요기술을 도출하여, 과학기술 일류 국가 실현, 국민소득 2만불 달성이라는 국가적 슬로건을 내걸고 “차세대 성장동력” 창출을 위한 범정부차원의 기획과 연구비의 집중투자를 추진하고 있다.달성하기 위해서는 종합류류 전산망의 시급한 구축과 함께 화물차의 적재율을 높이고 공차율을 낮출 수 있는 운송체계의 수립이 필요한 것으로 판단된다. 그라나 이러한 화물전용차선의 효과는 단기적인 치유책일 수밖에 없기 때문에 물류유통 시설의 확충을 위한 사회간접자본의 구축을 서둘러 시행하여야 할 것이다.으로 처리한 Machine oil, Phenthoate EC 및 Trichlorfon WP는 비교적 약효가 낮았다.>$^{\circ}$E/$\leq$30$^{\circ}$NW 단열군이 연구지역 내에서 지하수 유동성이 가장 높은 단열군으로 추정된다. 이러한 사실은 3개 시추공을 대상으로 실시한 시추공 내 물리검층과