• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1874-1878
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• 2008

본 연구에서는 물고기 서식처의 수리조건을 조사하기 위한 현장조사와 대상지에서의 미시서식처의 분포를 파악하기위한 수치계산을 실시하였다. 현장조사는 미호천과 금강이 합류되는 지점으로부터 약 24km 상류에 위치한 동경127도26분-북위36도41분 충북 청원군 오창면의 미호천 일부구간을 대상으로 수리학적 특성 조사, 지형측량 및 서식처별 대표어종 조사를 수행하였으며, 수치실험은 하천에서의 흐름거동을 2차원적으로 해석하는데 많이 사용되고 있는 상용프로그램인 SMS (Surface - Water Modeling System)의 RMA2 모형에 현장조사로부터 얻은 결과들을 입력함으로서 진행하였다. 그 결과 유속과 수심에 따른 서식처 구분이 가능하였으며, 현지특성을 재현한 수치모형 결과는 대상하천에서의 서식지 분포를 정량적으로 나타내었다.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.95-100
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• 2002

The first version of KHCM was Published in 1992 and is currently used in engineering Practice extensively. The study of new manual was initiated by Korea Institute of Construction Technology 1998 and is intended to be ready for publication by the year 2002. According to the field survey, the action of the individual merging vehicle creates turbulence in the vicinity of the ramp-freeway junction area. The purpose of this paper is to develop the model for Predicting the for entering the lanes 1 and 2($V_{12}$) and the density function at the influence zone by comがring the research works on the ramp junction in the USHCM 2000. The methodology has two major steps : the determination of the flow entering Lanes 1 and 2 immediately upstream of the merge influence area: and the density of the flow within the ramp influence area As a result of this paper the specific functions for such models are suggested through the regression analysis of data collected at four freeway fields in Korea.

• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.113-130
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• 2002

In this paper, we developed DNL(Dynamic Network Loading) model based on Moving cell theory to analyze the dynamic characteristics of traffic flow in congested network. In this paper vehicles entered into link at same interval would construct one cell, and the cells moved according to Cell following rule. In the past researches relating to DNL model a continuous single link is separated into two sections such as running section and queuing section to describe physical queue so that various dynamic states generated in real link are only simplified by running and queuing state. However, the approach has some difficulties in simulating various dynamic flow characteristics. To overcome these problems, we present Moving cell theory which is developed by combining Car following theory and Lagrangian method mainly using for the analysis of air pollutants dispersion. In Moving cell theory platoons are represented by cells and each cell is processed by Cell following theory. This type of simulation model is firstly presented by Cremer et al(1999). However they did not develop merging and diverging model because their model was applied to basic freeway section. Moreover they set the number of vehicles which can be included in one cell in one interval so this formulation cant apply to signalized intersection in urban network. To solve these difficulties we develop new approach using Moving cell theory and simulate traffic flow dynamics continuously by movement and state transition of the cells. The developed model are played on simple network including merging and diverging section and it shows improved abilities to describe flow dynamics comparing past DNL models.

• Journal of Korean Port Research
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• v.14 no.2
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• pp.175-185
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• 2000

Today freeway is experiencing a severe congestion with incoming or outgoing traffic through freeway ramps during the peak periods. Thus, the purpose of this study is to identify the traffic characteristics, analyze the relationships between the traffic characteristics and finally construct the delay predictive models on the rap junctions of freeway with 70mph speed limit. From the traffic analyses, and model construction and verification for delay prediction on the ramp junctions of freeway, the following results were obtained : ⅰ) Traffic flow showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period. ⅱ) The occupancy also showed a big difference depending on the time periods, and the downstream occupancy(Od) was especially shown to have a higher explanatory power for the delay predictive model construction on the ramp junctions of freeway. ⅲ) The delay-occupancy curve showed a remarkable shift based on the occupancies observed : O$\_$d/〈9% and O$\_$d/$\geq$9%. Especially, volume and occupancy were shown to be highly explanatory for delay prediction on the ramp junctions of freeway under O$\_$d/$\geq$9%, but lowly for delay prediction on the ramp junctions of freeway under O$\_$d/〈9%. Rather, the driver characteristics or transportation conditions around the freeway were thought to be a little higher explanatory for the delay prediction under O$\_$d/〈9%. ⅳ) Integrated delay predictive models showed a higher explanatory power in the morning peak period, but a lower explanatory power in the non-peak periods.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.57-66
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• 2007

Weaving is defined as the crossing of two or more traffic streams traveling in the same general direction along a significant length of highway without the aid of traffic control devices. Compared with other freeway sections, perturbation is easy to happen at weaving section. Because there are a lot of lane-changing maneuvers at the weaving section, traffic is subject to turbulence in excess of that normally presents on freeway basic section. This turbulence causes operational problems and its impact must be considered. The purpose of this paper is to perform a basic study on flow characteristics by lane, which can be achieved through analyzing breakdown phenomenon in the microscopic approach. The study made use of data derived from the aerial photography for the microscopic analysis. This research produced the 30-second interval data such as flows, speeds, and densities for the macroscopic analysis and derived the vehicular data to draw time-space diagram for the microscopic analysis. The paper analyzed the traffic characteristics using flows, speeds and densities variation and investigated the conditions of breakdown occurrence with the time-space diagrams. The breakdown phenomenon was identified at weaving section and the propagation from free flow to synchronized flow was observed in this study. In the future, the findings help develop the traffic operational algorithm to manage the traffic congestion under ubiquitous circumstance since the conditions of breakdown Phenomenon can be understood more.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.434-434
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• 2018

에코톱은 가장 작고 균일하며 도면의 단위로 사용 가능한 토지, 일반적인 구성요소의 상태, 잠재자연식생, 잠재생태계 기능을 최소한의 단위로 균일하게 분류가 가능한 요소로서 천이단계 또는 토지이용이 서로 다른 패치들로 이루어진 무생물과 생물이 결합된 생태공간으로서 일반적으로 세가지 특성을 포함한다. (1) 가장 작은 동질성 가진 지도로 분류 가능한 단위, (2) 일반적인 기질조건, 잠재적 자연식생 및 잠재적 생태계 기능에 대한 동질성, 그리고 (3) 서로 다른 연속적인 토지 이용 단계에서의 패치로 구성 된다. 현재 네덜란드, 스페인을 포함한 유럽국가에서는 에코톱분류를 통한 하천을 관리하는 방안을 제시하고 있으며 이에 대한 많은 연구가 진행되고 있다. 본 연구에서는 만경강 중류 소양천 합류점의 터지네 구간을 대상으로 하천공간의 복원 이후 연중유황에 따른 에코톱의 변화를 예측하고 이에 따른 개선효과를 정량적으로 분석하는 것이 목적이다. 제방 후퇴, 제방후퇴/구하도 복원, 제방 후퇴/습지 조성 세가지 복원 시나리오를 현재지형과 비교하여 연중 유황별 흐름조건에 따라 에코톱을 도식화 하였으며, 이에 따른 에코톱 다양성 지수를 도출하여 비교분석하였다. 복원 대상지의 복원 시나리오 및 흐름조건에 따른 에코톱의 변화를 분석한 결과 '제방 후퇴/구하도 복원' 일 때 자연요소가 현재지형보다 가장 크게 증가되었으며 3가지 복원 유형 간 자연요소를 비교한 결과 '제방 후퇴/구하도 복원' 일 때 수역과 일년생 초본이 가장 많은 면적을 차지하였으며, '제방 후퇴/습지 조성' 일 때 습지와 다년생 초본이 가장 많은 면적을 차지하였다. 복원 유형 별 연중 유황 조건에 따른 에코톱 다양성 지수분석결과 제방후퇴/습지 조성시 에코톱 다양성 개선효과가 가장 큰 것으로 나타났다.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.133-144
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• 2001

The purpose of this study is to develop micro simulation model for large-scale network with driver's behavior model. This study is performed for uninterrupted flow road section. And this model is developed to simulate traffic flow of the real network with unique geometric structure. The vehicle transmission and drivers' behavior model based on the exiting Cellular Automata approach.

• Journal of Korean Society of Transportation
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• v.28 no.2
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• pp.151-159
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• 2010

This paper presents a research result that was performed to develop a more accurate freeway crash prediction model than existing models. While the existing crash models only focus on developing crash relationships associated with highway geometric conditions found on a short section of a crash site, this research applies a different approach considering the upstream highway geometric conditions as well. Theoretically, crashes occur while motorists are in motion, and particularly at freeways vehicle speed at one specific point is very sensitive to upstream geometric conditions. Therefore, this is a reasonable approach. To form the analysis data base, this research gathers the geometric conditions of the West Seaside Freeway 269.3 km and six years crash data ranging 2003-2008 for these freeway sections. As a result, it is found that crashes fit well into Negative Binomial Distribution, and, based on the developed model, total number of crashes is inversely proportional to highway curve length and radius. Contrarily, crash occurrences are proportional to tangent length. This result is different from existing crash study results, and it seems to be resulted from this research assumption that a crash is influenced greatly by upstream geometric conditions. Also, this research provides the expected effects on crash occurrences of the length of downgrade sections, speed camera placements, and the on- and off- ramp presences. It is expected that this research result is useful for doing more reasonable highway designs and safety audit analysis, and applying the same research approach to national roads and other major roads in urban areas is recommended.

• Journal of Korean Society of Transportation
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• v.17 no.4
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• pp.71-84
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• 1999

The purpose of this study is to construct a dynamic traffic analysis model using the existing traffic flow theory in order to develope a dynamic traffic assignment technique. In this study the dynamic traffic analysis model was constructed using Daganzo's CELL TRANSMISSION THEORY which was considered more suitable to dynamic traffic assignment than the other traffic flow theories. We developed newly the diverging split module, the cost update module and the link cost function and defined the maximum waiting time decision function that Daganzo haven't defined certainly at his Papers. The output that resulted from the simulation of the dynamic traffic analysis model with test network I and II was shown at some tables and figures, and the analysis of the bottleneck and the HOV lane theory showed realistic outputs. Especially, the result of traffic assignment using the model doesn't show equilibrium status every time slice but showed that the average travel cost of every path maintains similarly in every time slice. It is considered that this model can be used at the highway operation and the analysis of traffic characteristics at a diverging section and the analysis of the HOV lane effect.

• Journal of Korean Port Research
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• v.14 no.1
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• pp.66-75
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• 2000

From the traffic analysis, and model constructions and verifications for speed prediction on the freeway ramp junctions with 70mph speed limit, the following results were obtained : ⅰ) The traffic flow distribution showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy distribution was also shown to be varied by a big difference depending on the time periods. Especially, the occupancy in the morning peak period showed over 100% increase when compared with the 24hours average occupancy, and the occupancy in the afternoon peak period over 25% increase when compared with the same occupancy. ⅲ) The speed distribution was not shown to have a big difference depending on the time periods. Especially, the speed in the morning peak period showed 10mph decrease when compared with the 24hours'average speed, but the speed did not show a big difference in the afternoon peak period. ⅳ) The analyses of variance showed a high explanatory power between the speed predictive models(SPM) constructed and the variables used, especially the upstream speed. ⅴ) The analysis of correlation for verifying the speed predictive models(SPM) constructed on the ramp junctions were shown to have a high correlation between observed data and predicted data. Especially, the correlation coefficients showed over 0.95 excluding the unstable condition on the diverge section. ⅵ) Speed predictive models constructed were shown to have the better results than the HCM models, even if the speed limits on the freeway were different between the HCM models and speed predictive models constructed.