• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.233-234
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• 2001

1997년부터 2000년 사이의 하절기(5~9월)의 평일(월~토요일)과 일요일(공휴일 포함)의 매 시간평균 미세먼지 및 오존의 농도특성을 분석하기 위하여 질소산화물(NOx), 오존(O$_3$), 미세먼지(PM10)등의 대기 오염물질을 한 시간단위로 자동측정하는 서울의 27개 측정소의 측정자료를 분석하였다. (중략)

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.131-137
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• 2004

Conventional traffic signal optimization models assume that green intervals for pedestrian crossings are given as exogenous inputs such as minimum green intervals for straight-ahead movements. As the result, in reality, the green intervals of traffic movements may not distribute adequately by the volume/saturation-flow of them. In this paper, we proposed signal optimization models formulated in BMILP to integrate pedestrian crossings into traffic movements under under-saturated traffic flow. The model simultaneously optimizes traffic and pedestrian movements to minimize weighted queues of primary queues during red interval and secondary queues during queue clearance time. A set of linear objective function and constraints set up to ensure the conditions with respect to pedestrian and traffic maneuvers. Numerical examples are given by pedestrian green intervals and the number of pedestrian crossings located at an arm. Optimization results illustrated that pedestrian green intervals using proposed models are greater than those using TRANSYT-7F, but opposite in the ratios of pedestrian green intervals to the cycle lengths. The simulation results show that proposed models are superior to TRANSYT-7F in reducing delay, where the longer the pedestrian green interval the greater the effect.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1995.10a
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• pp.122-123
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• 1995

• 한국ITS학회:학술대회논문집
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• 2008.11a
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• pp.109-113
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• 2008

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.663-669
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• 2011

In this study, the optimal length of left-turn lane in permissive left-turn signal system at the signalized intersection which has a left-turn bay is estimated. It is a simulation analysis using the queueing theory that estimate the length of left-turn lane. Traffic density conform to the standards of operating a permissive left-turn system of the Practical Manual Traffic Safety Facilities. And each of a left-turn arrival rate, a left-turn service rate, left-turn average queueing time, for green time average queueing vehicle, for red time average queueing vehicle and average queueing vehicle cycle is calculated. As a result of this study, we would learn how much the space should be secured at the signalized intersection which has a left-turn bay. The methodology using the queueing theory to work out the optimal length of waiting lane in the permissive left-turn signal system was presented.

• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.109-117
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• 2010

In this study, we consider stationary waiting times in a simple fork-and-join type queue which consists of three single-server machines, Machine 1, Machine 2, and Assembly Machine. We assume that the queue has a renewal arrival process and that independent service times at each node are either deterministic or non-overlapping. We also assume that the Machines 1 and 2 have an infinite buffer capacity whereas the Assembly Machine has two finite buffers, one for each machine. Services at each machine are given by FIFO service discipline and a communication blocking policy. We derive the explicit expressions for stationary waiting times at all nodes as a function of finite buffer capacities by using (max,+)-algebra. Various characteristics of stationary waiting times such as mean, higher moments, and tail probability can be computed from these expressions.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.461-462
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• 2003

산업의 발달과 함께 자연의 자정능력 한계를 넘어선 오염은 인간의 생존을 위협하는 심각한 사회문제로 대두되기에 이르렀다. 지금까지 대기오염에 대한 관심은 주로 실외대기, 즉 건물의 바깥쪽에 있는 대기오염에 편중되어 있었다. 대도시 및 중ㆍ소 공업 도시 등 대기오염이 문제되는 지역에서의 하루 생활은 하루 24시간 중 80％이상을 실내 공간에서 생활하고 있어 다양한 직업을 가진 현대인은 개인에 따라 다소 차이가 있지만 대기오염의 영향보다는 하루 중 많은 시간을 보내는 실내오염의 영향을 더 많이 받는다. (중략)

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.396-399
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• 2000

환경부가 발표한 21세기 대기환경관리 정책방향에서도 사업장의 대기오염 물질 관리강화를 포함시키고 있어, 이제 바야흐로 우리 나라도 사업장에 대한 과학적인 대기 환경관리 정책이 요구되고 있다. 그러나, 현재 대기확산예측 평가분야는 아직 국내기술이 미약하고, 사용되는 소프트웨어는 미국환경보호청에서 추천하는 모델을 사용하므로, 국내 실정에 맞는 데이터를 적용하기에 많은 인력과 시간을 소모해야 했다. 본 프로그램은 기존의 포트란으로 프로그램 된 소프트웨어보다 비주얼한 환경에 중점을 두고 C++언어로 프로그램 하였다. 또한, 국내 실정에 맞는 데이터를 사용하여 적은 비용과 짧은 시간 내에 대기확산예측을 할 수 있다.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.2
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• pp.29-39
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• 2018

In this paper, we discuss a discrete-time queueing system with dyadic server control policy that combines workload control and multiple vacations. Customers arrive at the system with Bernoulli arrival process. If there is no customer to serve in the system, an idle single server spends a vacation of discrete random variable V and returns. The server repeats the vacation until the total service time of waiting customers exceeds the predetermined workload threshold D. In this paper, we derived the steady-state workload distribution of a discrete-time queueing system which is operating under a more realistic and flexible server control policy. Mean workload is also derived as a performance measure. The results are basis for the analysis of system performance measures such as queue lengths, waiting time, and sojourn time.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.3
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• pp.59-72
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• 2017

As the part of study which handles the measure to use the individual vehicle information of taxi GPS data on signal controls in order to overcome the limitation of Loop detector-based collecting methods of real-time signal control system, this paper conducted series of evaluations and improvements on link travel time, queue vehicle time estimates and traffic condition decision algorithm from the research introduced in 2016. considering the control group and the other, the link travel time has enhanced the travel time and the length of queue vehicle has enhanced the estimated model taking account of the traffic situation. It is analyzed that the accuracy of the average link travel time and the length of queue vehicle are respectably both approximately 95 % and 85%. The traffic condition decision algorithm reflected the improved travel speed and vehicle length. Smoothing was performed to determine the trend of the traffic situation and reduce the fluctuation of the data, and the algorithms have refined so as to reflect the pass period on overflow judgment criterion.