• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.79-87
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• 2007

The interchanges of urban freeways have many problems with traffic operation due to high off-ramp flows and frequent congestion at adjacent intersections. The flow exiting from off-ramps is affected by the operational status and traffic volume conditions of the nearest signalized intersection. As a result, off-ramp flow cannot exit and the queue backs up the freeway mainline when queues from the signalized intersection form up to the junction of the off-ramp and street. The spacing between an off-ramp and an adjacent intersection is likely to determine the traffic conditions at the adjacent intersection. However, the current design guidelines do not consider such a factor. This study is to develop a model calculating the spacing between off-ramps and adjacent intersections considering the signal, traffic, and road conditions. The variables affecting the model in this study are effective green time (g/C), volume-capacity ratio (v/c), the number of lanes, and off-ramp volume. Various scenarios are designed to represent the effects of the variables and the road networks are constructed using VISSIM, which is a common traffic micro-simulation software package. The queue length is derived from VISSIM and this length is considered as the recommended spacing between the off-ramp and the adjacent intersection. Through the simulation analysis, regression models are developed to calculate the queue length reflecting the various conditions such as signals, traffic, and road configurations. The developed model can be used to create road design guidelines to determine the location of off-ramps in the planning stage.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.155-164
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• 2008

Variable Message Signs (VMS) is one of the major components for Intelligent Transport Systems (ITS) services that provides real-time traffic and incident information to drivers. The objective of this research was to develop a method determining the optimal location of VMS considering safety and driving characteristics of various drivers. A driving simulator was utilized to evaluate how drivers can safely exit to off-ramp depending on various VMS locations while information relating route diversion was provided. The binary logistic regression and factor analysis were applied in developing a probability model that predicts the success of safe off-ramp exiting. Based on the developed probability model, a method to estimate the spacing between VMS and off-ramp is suggested. It is expected that the products of this study would be utilized as a tool in determining VMS locations for ITS planners and designers.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.1
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• pp.123-140
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• 2022

Even though driving behaviors in underground roads can be significantly different from ground roads, existing underground roads follow the design guidelines of ground roads. In this context, this study investigates the driving behaviors of the exit-ramp terminal of urban underground roads using a driving simulator. Virtual driving experiments were performed by analyzing scenarios between the underground and ground road environments. The experiments' driving behavior data for each geometry section are compared and validated through a statistical significance test. This test showed that the speed in the underground road environment is relatively low, and the LPM tends to move away from the adjacent tunnel wall. Based on these findings, this study suggests implications and feasible solutions for improving driver's safety in the exit-ramp terminal of the underground roads.

• Journal of Korea Water Resources Association
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• v.32 no.5
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• pp.515-524
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• 1999

A methodology to resolve a TOPMODEL problem has been suggested, which is associated with the spatial distribution of soil moisture behaviour in a runoff mechanism. A procedure to integrate the spatial information of saturation deficit in the TOPMODEL reflects the connectivity of saturated area in a watershed. The developed algorithm includes an improved basis in tracing the runoff path without increasing the number of parameters. The performance of the developed algorithm has been tested to an upland subwatershed, namely Dongok, which is the IHP watershed located at Wichon, Korea. Comparing with the original statistical version of the TOPMODEL, it has been found that the suggested algorithm can relax an overestimation of peak rate in the runoff simulation.

• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.9-22
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• 2002

고속도로-연결로는 두 개의 교통흐름이 서로 상충되는 지점으로서 복잡한 교통행태를 나타내고 고속도로 구간 중 용량저하 및 교통와해현상, 난류현상이 일어나는 구간으로서 운영상 문제점이 많이 일어나고 있는 상태이다. 이 구간에서의 운영상태가 전체 시설물의 운영상태에 큰 영향을 끼친다는 점을 감안할 때, 이 구간의 국내자료를 토대로 한 교통류 분석은 중요한 의미를 가진다. 따라서, 교통행태에 대한 미시적인 분석이 이루어지지 않은 상태로 기존의 HCM 모형과 같은 거시적인 분석 방법만을 가지고는 분류구간 교통현상을 규명하기 어렵다. 본 연구에서는 기존 연구들 분석방법의 문제점을 해결하기 위해, 고속도로-연결로 구간중 유출부 구간을 대상으로 현장조사를 실시하였고, 지점(구간)과 차로로 세분하여 미시적인 방법으로 교통특성을 규명하였다. 또 한 유출부 구간의 여러 지점에서 지점 및 차로별 교통량을 예측할 수 있는 교통분포 모형식을 개발하였다. 정립된 교통분포 모형식을 적용해 본 결과 유출부 구간의 분석 및 서비스 수준의 평가는 연결로 접속차로(Vl)의 교통량만을 고려하여 분석하는 것은 합리적이지 않고, 연결로나 본선 모두와 진입부를 포함한 연결로 전체를 다 고려해야 한다는 것을 알 수 있었다. 미시적인 분석방법을 통한 차로별 교통분포 모형식은 기존 분석방법과 비교하여 더 정확하게 그리고 폭 넓은 분석 및 적용하기에 손쉬운 모형이라는 점에서 상당히 효과적인 분석방법이라고 할 수 있다. 하지만 본 연구의 결과는 한 조사지점에 대한 적은 자료를 토대로 하였기 때문에 실제적용 가능성에서 향후 보강할 필요가 있으며, 다른 지점의 현장조사와 세밀한 비교연구가 필요하다.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.157-161
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• 2011

Although many researches have been carried out concerning the watershed division in natural areas, it has not been researched for the urban watershed division. If the boundary between two urban areas is indistinct because no natural distinction or no administrative division is between the areas, the boundary between the urban areas that have the different outlets (multi-outlet urban watershed) is determined by only designer of sewer system. The suggested urban watershed division model (UWDM) determines the watershed boundary to reduce simultaneously the peak outflows at the outlets of each watershed. Then, the UWDM determines the sewer network to reduce the peak outflow at outlet by determining the pipe connecting directions between the manholes that have the multi-possible pipe connecting directions. In the UWDM, because the modification of the sewer network changes the superposition effect of the runoff hydrographs in sewer pipes, the optimal sewer layout can reduce the peak outflow at outlet, as much as the superposition effects of the hydrographs are reduced. Therefore, the UWDM can optimize the watershed distinction in multi-outlet urban watershed by determining the connecting directions of the boundary-manholes using the genetic algorithm. The suggested model was applied to a multi-outlet urban watershed of 50.3ha, Seoul, Korea, and the watershed division of this model, the peak outflows at two outlets were decreased by approximately 15% for the design rainfall.

• Journal of Korean Society of Transportation
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• v.24 no.7 s.93
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• pp.41-51
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• 2006

In this paper, a fundamental study on the characteristics of traffic accidents according to the alignment and traffic conditions on the ramp of freeway is addressed. The macro-and-micro scope analysis of characteristics about traffic accidents on the trumpet-IC ramps is conducted depending on the entering and exit ramp types under the various conditions of traffic volume and alignment And it is turned out that the conditions of alignment. such as radius, differences of curvatures, and main road grade, and traffic volume relate to the ramp accidents of trumpet IC according to ramp types, such as direction, semi-direction, and loop. Macroscopically, AR (Accident Rate) according to trumpet IC types, A and B, is analyzed nearly equal, but Number of accidents occurred in IC type B shows about 1.5 times higher than type A. And AR of exit ramps shows three times more than entrance ramps. Microscopically, ARs for each exit-ramp type, according to the increment of traffic volume, the difference of curvatures. and the first radius, exponentially decrease respectively. But relationships between AR and the second radius or exit ramp shows inverted U-shaped. AR according to main-road grade Peaks between -1.5% and -0.5%. It is expected that the developed models not only are employed to make design of trumpet-IC ramp more cost-efficiently and safely, but also contribute to making alternatives to the reduction of traffic accidents on trumpet IC ramps under the conditions of high traffic accident rate.

• Journal of Digital Convergence
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• v.12 no.5
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• pp.57-68
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• 2014

This article analyses frame transition of personal information leakage in Korea from 1984 to 2014. In order to investigate the transition, we have collected newspaper article's titles. This study adopts classification, text network analysis(by co-occurrence symmetric matrix), and clustering techniques as part of social network analysis. Moreover, we apply definition of centrality in network in order to reveal the main frame formed in each of four periods. As a result, accessibility of personal information is extended from public sector to private sector. The boundary of personal information leakage is expanded to overseas. Therefore it is urgent to institutionalize the protection of personal information from a global perspective.

• Journal of the Korean Data and Information Science Society
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• v.23 no.4
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• pp.693-701
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• 2012

Recently, the number of students who get double majors has tended to increase in many universities. As results, many problems occur because immoderate inflow of double-major students is concentrated in a specific popular department. In this paper, we study the characteristic of inflow and outflow of double majors using social network analysis and decision tree analysis. According to the results, SAT score affected the inflow of double majors the most. Additionally, department category, course evaluation score, employment rate also affected the inflow of double majors in the order named. On the other hand, department category affected the outflow of double majors the most. Additionally, SAT score, employment rate, course evaluation score also affected the outflow of double majors in the order named.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.202-202
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• 2018

본 논문에서는 분포형 강우-유출 모형인 GRM(Grid based Rainfall-runoff Model)(최윤석, 김경탁, 2017)을 이용해서 낙동강 유역을 대상으로 대유역 홍수해석시스템을 구축하고, 유출해석을 위한 실행시간을 평가하였다. 유출모형은 낙동강의 주요 지류와 본류를 소유역으로 구분하여 모형을 구축하고, 각 소유역의 유출해석 결과를 실시간으로 연계할 수 있도록 하여 낙동강 전체 유역의 유출모형을 구축하였다. 이와 같이 하나의 대유역을 다수의 소유역시스템으로 분할하여 모형을 구축할 경우, 유출해석시스템 구성이 복잡해지는 단점이 있으나, 소유역별로 각기 다른 자료를 이용하여 다양한 해상도로 유출해석을 할 수 있으므로, 소유역별 특성에 맞는 유출모형 구축이 가능한 장점이 있다. 또한 각 소유역시스템은 별도의 프로세스로 계산이 진행되므로, 대유역을 고해상도로 해석하는 경우에도 계산시간을 단축할 수 있다. 본 연구에서는 낙동강 유역을 20개(본류 구간 3개, 1차 지류 13개, 댐상류 4개)의 소유역으로 분할하여 계산 시간을 검토하였으며, 최종적으로 21개(본류 구간 3개, 1차 지류 13개, 댐상류 5개)의 소유역으로 분할하여 유출해석시스템을 구축하였다. 댐 상류 유역은 댐하류와 유량전달이 없이 독립적으로 모의되고, 댐과 연결된 하류 유역은 관측 방류량을 상류단 하천의 경계조건으로 적용한다. 지류 유역은 본류 구간과 연결되고, 지류의 계산 유량은 본류와의 연결지점에 유량조건으로 실시간으로 입력된다. 이때 본류와 지류의 유량 연계는 데이터베이스를 매개로 하였다. 유출해석시스템의 성능을 평가하기 위해서 Microsoft 클라우드 서비스인 Azure를 이용하였다. 낙동강 유역을 20개 소유역으로 구성한 경우에서의 유출해석시스템의 속도 평가 결과 Azure virtual machine instance DS15 v2(OS : Windows Server 2012 R2, CPU : 2.4 GHz Intel $Xeon^{(R)}$ E5-2673 v3 20 cores)에서 1.5분이 소요 되었다. 계산시간 평가시 GRM은 'IsParallel=false' 옵션을 적용하였으며, 모의 기간은 24시간을 기준으로 하였다. 연구결과 분포형 모형을 이용한 대유역 유출해석시스템 구축이 가능했으며, 계산시간도 충분히 단축할 수 있었다. 또한 추가적인 CPU와 병렬계산을 적용할 경우, 계산시간은 더 단축될 수 있으며, 이러한 기법들은 분포형 모형을 이용한 대유역 유출해석시스템 구축시 유용하게 활용될 수 있을 것으로 판단된다.