• 한국ITS학회:학술대회논문집
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• 2008.11a
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• pp.11-24
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• 2008

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.144-152
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• 2018

This study focuses on collecting traffic data using drones to compensate for limitation of the data collected by the existing traffic data collection devices. Feasibility analysis was performed to verify the traffic data extracted from drone videos and optimal methodology for extracting data was established through analysis of various data reduction scenarios. It was found from this study that drones are very economical traffic data collection devices and have strength of determining the level-of-service(LOS) for uninterrupted flow condition in a very simple and intuitive way.

• Journal of Korean Society of Transportation
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• v.23 no.3 s.81
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• pp.137-147
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• 2005

This study is to define new road capacity concept, and to develop and propose an estimation method, through the analysis of individual vehicular behaviors in continuum flow. Developments in detection technology enable various and precise traffic data collection. The U.S. HCM (Highway Capacity Manual) method does not require such various and precise traffic data, and outputs only limited results. Alternative capacity concepts, which can be classified into a stochastic model and behavioral or deterministic model, are attempts for modeling some prominent traffic flow features, namely so-called a capacity drop and a traffic hysteresis, using such various and precise traffic data. Yet, no capacity concept up-to-date can describe both features. The analysis of individual vehicular behaviors, including speed-density plot per time lap, traffic flow-speed-density diagram per each sampling interval, time headway distribution, and free flow speed distribution, is performed for overcoming the limits of the previous capacity concepts. A stochastic methods are applied to determine time headway for estimating freeway capacity for traffic control.

• Proceedings of the KOR-KST Conference
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• 1998.10b
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• pp.295-295
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• 1998

고속도로에서 교통류의 특성에 파악하여 교통류의 특성을 파악하여 동적행태로 교통상황을 분석하고 효과적인 제어전략, 시뮬레이션, 그리고 기하구조 개선등의 효율적이고 실용적인 적용을 위해서는 교통류의 정확한 모사가 필요하다. 시공간으로 표현되는 상태방정식을 포함하는 거시적 시뮬레이션 모델에 사용되는 연속류 모델은 이러한 교통류 특성을 모사하는데 적절하다. Lighthill과 Whitham(1955), Richard(1956)에 의해 일계도함수의 형태를 가지는 단순모델이 제시된 이후 모델의 결점을 보완하기 위해 많은 고계도 모델이 제시되었지만 고계도 모델이 가진 이론적인 결점에 대해서는 여러 연구들이 제시되어 있다. 또한 고계도 모델은 운동량 방정식의 유도, 정산, 구현의 어려움으로 널리 사용되기 힘들다는 단점을 가지고 있다. 만일 적절히 구현할 수 있다면 적용이 간단한 단순모델로도 보다 정확한 교통류 상황 모사가 가능하다. Ansorge는 혼잡교통류상황을 보다 정확하게 모사하기 위해 단순모델에 엔트로피 조건을 결합시킨 모델을 제시했다. Bui는 이 제안된 모델이 적절한 시뮬레이션 결과를 나타낸다는 것을 밝혔다. 그러나 이 모델은 차량의 재가속이 이루어지는 교통상황-stop-start wave의 경우 비현실적인 값을 가진다. 엔트로피조건에 의해 구해진 해는 실제보다 과다한 교통량을 추정하게 되는데 이런 결과는 위와 같은 교통상황에서 중요한 요소로 작용하는 가속효과가 무시되고 있기 때문이다. 따라서 본 연구에서는 stop-start wave 조건에서 가속도에 경계치를 부여하여 교통류율을 상한경계조건을 제시함으로써 교통상황에 맞는 교통류율을 산정하는 방법에 대해 제안하고자 한다.환승이라는 특정대안변수(Specific alternative variable)를 첨가하여 그것이 수단선택에 미치는 영향을 분석한다. 또한, 대중교통의 속성을 가지고 있는 지하철과 버스를 하나의 대안으로 묶어서 효용함수를 구한 다음 다시 승용차, 택시, 대중교통을 독립된 대안으로 두고 모형을 정립하는 NESTED LOGIT모형으로 파라메타를 추정하여 대중교통의 효용에 관해 분석·비교하였다. 본 논문에 이용된 자료는 공항을 이용하는 이용객들을 대상으로 직접 설문·면접조사한 자료이며 대상 교통수단은 승용차, 택시, 지하철, 버스로 설정하였다. 결과 적응형 알고리즘이 개개인의 최단시간 경로를 제공하는 사용자 평형 경로안내전략에 비해 교통혼잡도와 정체시간의 체류정도에 따라 3%에서 10%까지 전체통행시간을 절약할 수 있다는 결론을 얻었다.출발참, 구성대외개방선면축심, 실현국제항선적함접화국내항반적전항, 형성다축심복사식항선망; 가강기장건설, 개피포동제이국제기장건설, 괄응포동개발경제발전적수요. 부화개시일은 각 5월 26일과 5월 22일이었다. 11. 6월 중순에 애벌레를 대상으로 처리한 Phenthoate EC가 96.38%의 방제가로 약효가 가장 우수하였고 3월중순 및 4월중순 월동후 암컷을 대상으로 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 정압주입시험에서도 확인된다.. It was result

• Journal of Korean Society of Transportation
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• v.34 no.2
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• pp.146-157
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• 2016

The objective of this study is to actualize a statistical model of the 3-detector simplification model, which was proposed to detect outbreak situations by Daganzo in 1997 and to verify the statistical appropriacy thereof. This study presents the calculation process of the 3-detector simplification model and realizes the process using a statistics program. Firstly, the model was applied using data on detector of the main highways on which there is no entrances or exits. Moreover, in order to statistically verify the 3-detector simplification model, accumulative traffics for 30 seconds period, which reflects the dynamic changes of traffics due to shock wave, were estimated for outbreak traffics and steady flow, and the error of acquired data was statistically compared with that of the actual accumulative traffics. As a result, the error ratio between steady and incident cumulative flows has reached its maximum after 2-3 hours from an accident. Moreover, the incident traffic flows by accidents and the stade flows are heterogeneous in terms of their dispersion and means.

• 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.

• 한국디지털정책학회:학술대회논문집
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• 2004.05a
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• pp.593-608
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• 2004

우리나라의 경우 교통정보수집용 검지기는 루프검지기가 주종을 있으며, 지금까지 한국에서 루프검지기를 대체할 수 있는 영상 및 초단파검지기와 같은 대체검지기에 대한 평가는 단속류 보디는 연속류 상황에 대한 평가로 제한되어 왔다. 한편 최근들어 점차 고속도로를 중심으로 영상검지기의 설치개소수가 급속히 증가하고 있는 추세이다. 이 영상검지기의 경우 연속 교통류 상황의 15 분 혹은 5 분 단위의 점유율, 교통량, 속도등의 교통변수 측정정확도는 검지시스템의 요구사항을 충족하는 것으로 나타났다. 본 연구에서는 한국의 장래 교통관리 첨단화에 요구되는 교통자료 수집수준을 시가지도로 및 고속도로를 중심으로 파악하고, 루프검지기의 대체 검지기로서 영상검지기에 대한 성능평가 및 분석을 실시하였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.4
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• pp.92-106
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• 2017

The adverse weather is known as a factor that interrupts traffic flow and causes traffic accidents and traffic congestion by lowering visibility of drivers. Especially, in case of fog unlike any other weather conditions, traffic accidents lead to serious accidents and the fatality of the accidents is known to be high. This paper aims to analyze uninterrupted traffic flow characteristics under foggy conditions among adverse weathers. The traffic volumes and speeds under foggy and normal conditions were analyzed. Results indicated that fog with low visibility causes the most insignificant reduction in traffic volumes. On the other hand, the reduction in the speeds due to low visibility was evident. In addition, the relationship between flow, speed, and density in fog were analyzed. Analysis results showed that the fog with less than 200m visibility had clear impact on traffic flow.

• Journal of Korean Society of Transportation
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• v.27 no.3
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• pp.71-77
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• 2009

The ubiquitous transportation system environments make it possible to collect each vehicle's position and velocity data and to perform more sophisticated traffic flow management at individual vehicle or platoon level through V2V and V2I communications. The VISSIM simulation experiments were performed to address the issues in developing the preventive congestion management algorithm proposed in the companion paper. Traffic flow stability measures were developed based on the platoon profile, which enables us to explicitly consider traffic flow stability in traffic flow management. Traffic flow management strategies according to the traffic flow states were proposed: Maintain the equilibrium speed for free flow state, maintain the traffic flow stability by platoon control for critical state, and surpress the shock wave propagation for congested state. And finally potential benefit of the proposed traffic flow management scheme was evaluated based on the simulation experiment results. It is considered that extensive field experiments should be performed to confirm the simulated results.

• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.67-79
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• 2002

In this paper, observed trajectories of a vehicle platoon are viewed as one realization of a finite sequence of random trajectories. In this point of view, we develop novel and mathematically rigorous concept of traffic flow variables such as local traffic density, instantaneous traffic flow, and velocity field and investigate their nature on a general probability space of a sequence of random trajectories which represent vehicle trajectories. We present a simple model of random trajectories as an illustrative example and, derive the values of traffic flow variables based on the new definitions in this model. In particular, we construct the model for the sequence of random vehicle trajectories with a system of stochastic differential equations. Each equation of the system nay represent microscopic random maneuvering behavior of each vehicle with properly designed drift coefficient functions and diffusion coefficient functions. The system of stochastic differential equations nay generate a well-defined probability space of a sequence of random vehicle trajectories. We derive the partial differential equation for the expected cumulative plot with appropriate initial conditions. By solving the equation with numerical methods, we obtain the values of expected cumulative plot, local traffic density, and instantaneous traffic flow. In addition, we derive the partial differential equation for the expected travel time to a certain location with appropriate initial and/or boundary conditions, which is solvable numerically. We apply this model to a case of single vehicle trajectory.