• Title/Summary/Keyword: interrupted flow

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Population analysis of eelgrass, Zostera marina L. in Geojedo, Gaedo, and Jedo on the southern coastal water of Korea using RAPD-PCR (RAPD 방법을 이용한 거제도, 개도, 제도해역에서 채집한 말잘피 개체분석)

  • Cho, Eun-Seob;Lee, Sang-Yong;Kim, Jeong-Bae
    • Journal of Life Science
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    • v.17 no.4 s.84
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    • pp.455-461
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    • 2007
  • Assessments of population genetic structure and diversity can be of value in formulating management plans for threatened eelgrass(Zostera maim). Using randomly amplified polymorphic DNA markers, we found evidence of significant genetic structure among the populations of eelgrass sampled at three areas(Geojedo, Gaedo, and Jedo). A highly isolated(>100 km apart) population from the Geojedo had a long genetic distance(0.16), whereas the populations from the Gaedo and Jedo(<10 km apart) exhibited far less distance(0.08). The analysis of similarity within population showed that Geojedo was over 70%, which was of lower value than of Gaedo and Jedo. Based on these results, we realized that heterogeneous population was in accordance with geographic separation. This is caused by limited seed dispersal and interrupted gene flow, although the sample size is small.

Multi-Agent for Traffic Simulation with Vehicle Dynamic Model I : Development of Traffic Environment (차량 동역학을 이용한 멀티에이전트 기반 교통시뮬레이션 개발 I : 교통 환경 개발)

  • 조기용;권성진;배철호;서명원
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.5
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    • pp.125-135
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    • 2004
  • The validity of simulation has been well-established for decades in areas such as computer and communication system. Recently, the technique has become entrenched in specific areas such as transportation and traffic forecasting. Several methods have been proposed for investigating complex traffic flows. However, the dynamics of vehicles and their driver's characteristics, even though it is known that they are important factors for any traffic flow analysis, have never been considered sufficiently. In this paper, the traffic simulation using a multi-agent approach with considering vehicle dynamics is proposed. The multi-agent system is constructed with the traffic environment and the agents of vehicle and driver. The traffic environment consists of multi-lane roads, nodes, virtual lanes, and signals. To ensure the fast calculation, the agents are performed on the based of the rules to regulate their behaviors. The communication frameworks are proposed for the agents to share the information of vehicles' velocity and position. The model of a driver agent which controls a vehicle agent is described in the companion paper. The vehicle model contains the nonlinear subcomponents of engine, torque converter, automatic transmission, and wheels. The simulation has proceeded for an interrupted and uninterrupted flow model. The result has shown that the driver agent performs human-like behavior ranging from slow and careful to fast and aggressive driving behavior, and that the change of the traffic state is closely related with the distance and the signal delay between intersections. The system developed shows the effectiveness and the practical usefulness of the traffic simulation.

Influences of An Extreme Flood on Habitual Environment of Aquatic Ecosystem of Urban Stream (거대홍수가 도시하천의 수생생태계 서식환경에 미치는 영향)

  • Son, Myoung-Won
    • Journal of the Korean association of regional geographers
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    • v.14 no.2
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    • pp.105-113
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    • 2008
  • The purpose of this paper is to analyze the influences of extreme flood on urban stream's habitat environment at Shincheon stream in Daegu. In case of Shincheon stream, as any extreme floods have not flowed over the artificial bank, an extreme flood have an effects on inner part of confined channel. To make riparian park along Shincheon channel, Concrete and rubber weirs are constructed. These weirs interrupted flow of running water as obstacles during extreme flood, and running water moved aside into and destructed banks of lower-flow-channel. In reach of no weir, as all small-scale topographic bedforms were eliminated, habitat environment of river ecosystem was simplified, and biodiversity of river ecosystem was decreased. As simplified riverbed become irregular bedforms through frequent small-scale-floods, river ecosystem will become vigorous.

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A Path-based Traffic Flow Simulation Model for Large Scale Network (기종점 기반 대규모 가로망 교통류 시뮬레이션 모형)

  • 조중래;홍영석;손영태
    • Journal of Korean Society of Transportation
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    • v.19 no.3
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    • pp.115-131
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    • 2001
  • The Purpose of this study is to develop a simulation model for large-scale network with interrupted flow as well as uninterrupted flow. The Cell Transmission(CT) theory is used to simulate traffic flow. Flow transition rules have been newly developed to simulate traffic flows at merging and diverging sections, and signalized intersections. In the model, it is assumed that dynamic OD table is exogenously given. Simulation results for toy network shows that the model can explain queue dynamics not only in signalized intersections of urban arterials, but also in merging and diverging sections of freeway. In case study, the model successfully simulated traffic flows of 145,000 vehicles on CBD network of city of Seoul with 74 traffic zones, 133 signalized intersections among 395 nodes and 1110 links.

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Development of Vehicle Arrival Time Prediction Algorithm Based on a Demand Volume (교통수요 기반의 도착예정시간 산출 알고리즘 개발)

  • Kim, Ji-Hong;Lee, Gyeong-Sun;Kim, Yeong-Ho;Lee, Seong-Mo
    • Journal of Korean Society of Transportation
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    • v.23 no.2
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    • pp.107-116
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    • 2005
  • The information on travel time in providing the information of traffic to drivers is one of the most important data to control a traffic congestion efficiently. Especially, this information is the major element of route choice of drivers, and based on the premise that it has the high degree of confidence in real situation. This study developed a vehicle arrival time prediction algorithm called as "VAT-DV" for 6 corridors in total 6.1Km of "Nam-san area trffic information system" in order to give an information of congestion to drivers using VMS, ARS, and WEB. The spatial scope of this study is 2.5km~3km sections of each corridor, but there are various situations of traffic flow in a short period because they have signalized intersections in a departure point and an arrival point of each corridor, so they have almost characteristics of interrupted and uninterrupted traffic flow. The algorithm uses the information on a demand volume and a queue length. The demand volume is estimated from density of each points based on the Greenburg model, and the queue length is from the density and speed of each point. In order to settle the variation of the unit time, the result of this algorithm is strategically regulated by importing the AVI(Automatic Vehicle Identification), one of the number plate matching methods. In this study, the AVI travel time information is composed by Hybrid Model in order to use it as the basic parameter to make one travel time in a day using ILD to classify the characteristics of the traffic flow along the queue length. According to the result of this study, in congestion situation, this algorithm has about more than 84% degree of accuracy. Specially, the result of providing the information of "Nam-san area traffic information system" shows that 72.6% of drivers are available.

Machinability Evaluation according to Variation of Endmill Shape for High Speed Machining (고속가공용 엔드밀 형상변화에 따른 가공성 평가)

  • Kang, Myung-Chang;Kim, Jeong-Suk;Lee, Deuk-Woo;Kim, Kwang-Ho;Ha, Dong-Geun
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.5
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    • pp.133-138
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    • 2002
  • The technique of high speed machining is widely studied in machining fields, because the high efficiency and accuracy in machining can be obtained in high speed machining. Unfortunately the development of tool fur high speed machining in not close behind that of machine tool. In this study, 10 types flat endmill is prepared for obtaining data according to tool shape. Especially, we concentrated in helix angle, number of cutting edge and rake angle. Cutting condition is selected for several experiments and measuring cutting farce, tool life, tool wear and chip shape according to cutting length. 3-axis cutting farces are acquired from the tool dynamometer with high natural frequency, as the conventional tool dynamometer (9257B, Kistler) has cannot measure the state of high frequency force. Particularly, we found out that the axial cutting force waveform has a good relation with tool wear features. And flow is interrupted at the beginning of cutting by the decrease of rake angle. By above results. it is suggested the endmill tool with 45$^{\circ}$helix angle, 6 cutting edge and -15$^{\circ}$rake angle is suitable for high speed machining.

Comparison between Congestion Levels and Amount of $CO_2$ Emissions on Arterials (단속류 간선도로에서 지정체와 $CO_2$ 배출량 비교)

  • Gang, Jin-Gu;O, Heung-Un
    • Journal of Korean Society of Transportation
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    • v.29 no.6
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    • pp.17-23
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    • 2011
  • It has been presumed that the amount of vehicle's $CO_2$ emission would highly related to vehicle's cruising speeds on highways. In this study, it was tested if vehicle's $CO_2$ emissions would relate to the types of highways and the level of congestion. The results showed that the amount of $CO_2$ emission changes depending on (1) the vehicles' cruising speeds (b) congestion levels, and (c) the types of intersections. It was found that the vehicle acceleration and deceleration methods increases the amount of $CO_2$ emission up to 12%. It was also found that it changed up to 30% and 40% depending on the level of congestion and the types of intersections, respectively. The findings imply that the amount of $CO_2$ emission from vehicles should be improved when vehicles' cruising speeds are well managed through congestion management.

Factor Analysis of Accident Types on Urban Street using Structural Equation Modeling(SEM) (구조방정식모형을 활용한 단속류 시설의 교통사고 유형별 유발요인 분석)

  • Kim, Sang-Rok;Bae, Yun-Gyeong;Jeong, Jin-Hyeok;Kim, Hyeong-Jin
    • Journal of Korean Society of Transportation
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    • v.29 no.3
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    • pp.93-101
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    • 2011
  • In 2008, Korea has observed total 215,822traffic accidents Although the number has decreased since then, the crash rate is still higher than those of other advanced countries. In particular, high rate of pedestrian accidents occurred on urban streets is recognized as a serious problem. The previous studies, however, are not entirely considerate of accident factors by accident type. Inspired by the fact, this study analyzes factors affecting traffic accident by accident type. Using the accident data collected on urban streets in Seodaemun-gu, this paper classifies the accidents into two groups (i.e., vehicle-vs-vehicle and vehicle-vs-person crashes), and analyzes relationships between severity and exogenous variables. For the analysis, Structural Equation Modeling (SEM) is employed to estimate relationships among exogenous factors of traffic accident by each type on urban streets. The resulting model reveals that roadway related factors are highly correlated with the severity of vehicle-vs-vehicle crashes whereas environment factors are with vehicle-vs-person crashes.

A Traffic Assignment With Intersection Delay for Large Scale Urban Network (대규모 도시부 교통망에서의 이동류별 회전 지체를 고려한 통행배정연구)

  • Kang, Jin Dong;Woo, Wang Hee;Kim, Tae Gyun;Hong, Young Suk;Cho, Joong Rae
    • Journal of Korean Society of Transportation
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    • v.31 no.4
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    • pp.3-17
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    • 2013
  • The purpose of this study is to develop a traffic assignment model where the variable of signal intersection delay is taken into account in assigning traffic in large-scale network settings. Indeed, despite the fact that the majority of the increase in travel time or cost involving congested urban network or interrupted flow are accounted for by stop delays or congested delays at signal intersections, the existing traffic assignment models did not reflect this. The traffic assignment model considering intersection delays presented in this study was built based on the existing traffic assignment models, which were added to by the analysis technique for the computation of intersection delay provided in Korea Highway Capacity Manual. We can conclude that a multiple variety of simulation tests prove that this model can be applied to real network settings. Accordingly, this model shows the possibility of utilizing a model considering intersection delay for traffic policy decisions through analysis of effects of changes in traffic facilities on large urban areas.

An Experimental Study on Surfactant Enhanced LNAPL Removal Behavior in Saturated Zone (계면활성제를 이용한 포화지층내 저비중 비수용성 유기용매의 제거거동에 관한 연구)

  • 이재원;박규홍;박준범;임경희
    • Journal of the Korean Geotechnical Society
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    • v.15 no.5
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    • pp.291-300
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    • 1999
  • Surfactant flushing for enhancing the removal of BTEX from contaminated sand/clay mixtures was investigated. Eight soil columns packed with relatively undisturbed BTEX contaminated soils, were leached with water, methyl alcohol and then flushed with surfactant with or without several additives. Initial concentrations of BTEX mixture range from 278mg/kg to 1975mg/kg. Initial BTEX removal efficiency was 98% when the contaminated soil was flushed with water of 850 pore volumes. Because of tailing effect, water flushing could not remove below 8mg/kg concentrations during the experimental period. Eventually, the most effective surfactant for flushing was turned out to be 4% SOFTANOL(equation omitted)-90 with 3% ethyl alcohol and 3% SXS. In interrupted flow conditions, the removal efficiency was 99.5% with the flushed water of 95 pore volumes. The BTEX mixture removed from the soil columns during the surfactant flushing ranges from 84.5% to 99.5% of the initial amount for both water leaching(850 pore volumes) and surfactant flushing(95-165 pore volumes), respectively. Test results indicated that surfactant flushing could enhance the removal of BTEX mixture from contaminated soils and could reduce the aqueous phase BTEX mixture concentration in leachate.

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