• Journal of the Korea Society for Simulation
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• v.24 no.2
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• pp.11-17
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• 2015

Although systems with finite capacities have been the topic of much study, there are as of yet no analytic expressions for (higher) moment and tail probability of stationary waiting times in systems with even constant processing times. The normal queueing theory cannot properly handle such systems due to the difficulties caused by finite capacity. In this study, for a DBR (Drum-Buffer-Rope) line production system with constant processing times, we introduce analytic expressions by using previous results obtained using a max-plus algebraic approach.

• Journal of Korean Society of Transportation
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• v.12 no.4
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• pp.89-97
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• 1994

신호화된 교차로의 운영비율을 측정하기 위해 현재 세계적으로 광범위하게 이용되 는 척도는 교차로 통과차량의 평균지체시간이다. 그간 교차로 분석을 위해 많은 대기행렬 모형이 발표되어 왔고 또 그중 일부가 현재 사용 중에 있는데 이들은 모두 steady-state를 가정한 해법이다. 그러나 steady-state 모형은 시간에 따른 대기행렬 길이의 변화를 고려하 지 못하므로 현실적인 분석에 한계가 있는 방법론이다. 그러므로 정당한 교차로 시간산출을 위해서는 time-dependent한 분석형의 개발이 요구된다. 본 연구에서는 discrete Markov chain을 이용하여 단순히 단위시간 동안의 도착율과 출발율로써 transition probabilities를 계산하는 새로운 대기행렬 모형을 개발하였다. 개발된 불연속 대기행렬 모형을 이용하여 교 차로 분석을 할 경우 기존의 교차로 지체모형과 비교하여 기대되는 개선효과는 다음과 같 다. 변화를 고려한 dynamic한 분석으로 현실적이고 정당한 예측을 할 수 있다. 신호자동에 의한 영향을 분석할 수 있다. 그리고 독립적교차로 뿐만 아니라 간선도로, 나아가서 network 분석을 할 수 있으며, 동시에 주어지 교통여건에 대해 신호자동화를 위한 최적값을 산출해 낸다.

• Journal of Korean Society of Transportation
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• v.18 no.2
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• pp.73-89
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• 2000

This Paper documents the development of a cycle free based, coordinated dynamic signal timing model for minimizing queue lengths using Genetic A1gorithm. The model was embodied using MAT-LAB, the language of technical computing. A special feature of this model is its ability to manage queue lengths of turning movements at the start of green times. The model produces a cycle-free based signal timing(cycles and green times) for each intersection to minimize queue lengths of turning movements on the cycle basis. Concurrently, appropriate offsets could be accomplished by applying cycle-free based signal timings for respective intersections. The model was applied to an example network which consists of three intersections. The result shows that the model produces superior signal timings to the existing signal timing model in terms of managing queue lengths of turning movements.

• The Journal of the Korea Contents Association
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• v.11 no.7
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• pp.219-224
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• 2011

To improve medical service and customers' satisfaction by reducing actual waiting time for medical inspection by personalized examination guidance contents (PEGC) linked with medical information system (MIS). The suggested PEGC was completed with preparing transmission for data and PEGC by using transmission control protocol internet protocol (TCP/IP) which can be built up creditable data transmission service. When patient signal event appeared in MIS while the communication was in standby, the ID and data of the customer were shown as text and image on monitors in waiting room. Guiding inspections, steps of examination, and undressing information extracted from the PEGC was also shown to the appropriate patient. After installation of the suggested PEGC, we rechecked satisfaction rates of 60 customers who visited the hospital with a same method as initial survey. The results of this study suggest that 3.6 point of waiting time satisfaction index were improved, after installation of the suggested PEGC, as 4.6 point.

• Journal of the Korea Society for Simulation
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• v.25 no.3
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• pp.117-123
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• 2016

This paper presents inference methods for inner operations of a multi-server queue when historical data are limited or system observation is restricted. In a queueing system analysis, autocorrelated arrival and service processes increase the complexity of modeling. Accordingly, numerous analysis methods have been developed. In this paper, we introduce an inference method for specific situations when external observations exhibit autocorrelated structure and and observations of internal operations are difficult. We release an assumption of the previous method and provide lemma and theorem to guarantee the correctness of our proposed inference method. Using only external observations, our proposed method deduces the internal operation of a multi-server queue via non-parametric approach even when the service times are autocorrelated. The main internal inference measures are waiting times and service times of respective customers. We provide some numerical results to verify that our method performs as intended.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.623-625
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• 1999

초기 대기시간의 감소는 동시에 지원할 수 있는 사용자 수의 최대화와 함께 비디오 저장 서버가 상용 서비스에 사용되기 위해서 갖추어야 할 필수적인 요소이다. 본 논문에서는 각 디스크의 부하가 균형을 이루고, 새로운 사용자의 디스크 읽기 요구를 우선적으로 처리하는 방법으로 초기 대기시간이 일정 시간을 넘지 않도록 하는 디스크 배치 방법과 스케쥴링 방법을 제안하고, 이러한 방법을 구현하는데 필요한 시스템 변수들의 설정 방법을 제안한다. 또한 기존의 방법과의 비교를 통하여 제안한 방법의 우수한 성능 향상이 있음을 보인다.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.19-29
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• 2003

The purpose of this study is to analyse the effect of the parking information on the waiting time using the simulation method. Stated Preference survey has been implemented to construct the parking lot choice model. A queue simulation is carried out to investigate the effect of various parking information on the waiting time. The results show that providing parking information is likely to increase the utilization of parking place and to decease the waiting time of individual vehicle. Furthermore, as the parking demand increases, the detailed and quantitative parking information such as "5 minutes delay" is more effective than qualitative parking information such as "available".

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.12
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• pp.277-286
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• 2019

The Unmanned Aerial Vehicle (UAV) is one of the most precious inventions of Internet of things (IOT). UAV faces the necessity to charge battery or replace battery from the charging stations during or between services. We propose scheduling algorithms for drone power charging (SADPC). The basic idea of algorithm is considering both a deadline (for increasing deadline miss ratio) and a charging time (for decreasing waiting time) to decide priority on charging station among drones. Our simulation results show that our power charging algorithm for drones are efficient in terms of the deadline miss ratio as well as the waiting time in general in compare to other conventional algorithms (EDF or SJF). Also, we can choose proper algorithms for battery charge scheduling and charge ready battery allocation according to system parameters and user requirements based on our simulation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1087-1094
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• 2013

This study aims at enhancing the objective estimation of social cost of air quality due to mobile emission. More specifically, it examines the difference between the daily oriented and hourly oriented estimation results of social air quality cost and draws implications from the comparative analysis. The result indicates that the social cost of air quality differs up to approximately 24 times depending on the analysis time period. Moneywise, the difference between daily and hourly assignments amounts to the average of 653.5 billion won whereas only 1% of error occurred in the estimation result based on peak and nonpeak based hourly assignment. This study reaffirms the need for time-based travel demand management for emission reduction, and confirms the feasibility of emission estimation by travel demand forecasting method over the conventional method employed by the CAPSS.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.04a
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• pp.108-109
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• 2000

도시대기 중에서 질소산화물과 공존시 태양광의 작용을 받아 광화화학 반응을 일으키는 동시에 사람의 건강상에 유해한 성분(발암성 혹은 돌연변이성)들이 많이 존재하는 것으로 알려진 대기오염물질 중에서도 탄화수소성분에 대한 관심이 최근 들어 고조되고 있다. 본 연구에서는 도시 도로변에서 시료를 24시간 연속적으로 채취하여 휘발성유기회합물(Volatile Organic Compounds;이하 VOCs)의 시간별 농도수준 및 거동을 파악하고 나아가 각 VOCs 농도에 영향을 주는 인자에 대해 평가하고자 한다. (중략)