대기행렬이론을 활용한 의료서비스 환자 대기환경 평가

여현진 ( Hyun Jin Yeo ),박원숙 ( Won Sook Bak ),유명철 ( Myung Chul Yoo ),박상찬 ( Sang Chan Park ),이상철 ( Sang Chul Lee ) 한국품질경영학회 2014 품질경영학회지 Vol.42 No.1

Purpose: The purpose of this study is to develop the methods for evaluating patients` queue environment using decision tree and queueing theory. Methods: This study uses CHAID decision tree and M/G/1 queueing theory to estimate pain point and patients waiting time for medical service. This study translates hospital physical data process to logical process to adapt queueing theory. Results: This study indicates that three nodes of the system has predictable problem with patients waiting time and can be improved by relocating patients to other nodes. Conclusion: This study finds out three seek points of the hospital through decision tree analysis and substitution nodes through the queueing theory. Revealing the hospital patients` queue environment, this study has several limitations such as lack of various case and factors.

Minimization of Concave Holding Costs in Queueing System

Seungbum Soh(서승범) 연세대학교 경영연구소 2020 연세경영연구 Vol.57 No.2

기초적인 cµ 규칙이 발견된 시기부터 대기 시간과 관련한 비용을 최소화하는 것은 대기행렬이론에서 가장 중요한 문제 중 하나였다. 대기 시간 비용 최소화와 관련한 기초적인 결과는 비용이 선형적으로 증가한다는 가정에 의거한 것이었고 더 일반적인 볼록 함수비용의 경우 대기행렬을 근사하는 기법을 이용하여 최적해를 구했다. 지금까지 다양한 설정에서 어떤 최적해가 가능한지에 대한 연구가 이루어졌지만 선형 함수나 볼록 함수가 아닌 대기 비용 함수의 경우 최적해의 성질은 어떻게 되는지에 대해서는 충분한 연구가 이루어지지 않았다. 본 연구는 특히 연구가 이루어지지 않은 오목 비용 함수에 대해 다룬다. 본 연구 역시 대기행렬 근사를 통해 최적해를 도출한다. 본 연구에서는 고객 집단이 세분화되어있을 때 서비스 우선권이 어떻게 배분되어야 하는지를 다룬다. 모든 고객군의 대기 비용이 오목 비용 함수인 경우 온오프 조절(bang bang policy)이 최적해의 집합에 반드시 포함된다는 것을 보였고, 특히 대기 비용이 강오목함수인 경우 온오프 조절만이 최적해라는 것을 보였다. 이 특성을 통해 오목 비용 함수를 최소화하는 일반해를 도출한다. 추가적으로 모든 대기열이 하나의 고객군에 집적되는 것이 최적이도록 하는 조건도 도출된다. Since the advent of basic cµ rule, minimization of holding costs has been one of the most fundamental problems in queueing theory. The first results on holding cost minimization was under the linear cost assumption and the more general case of convex costs has been solved with help of queueing approximation method named heavy traffic. Even with many sophisticated solutions on general settings, there is scarce literature that goes beyond convex or linear cost structure. Especially, a holding cost minimization problem with concave cost structure has not been discuessed yet. As far as we know, our work is the first to study concave cost structure in queueing theory. We study how the customers from multiple classes should be prioritizized. We figure out that so-called bang-bang policy is always included in the set of optimal prioritization policies when the costs are concave and that all the optimal solutions to strict concave costs are bang-bang. With this property, we construct a simple and general solution for the concoave cost minimization problem. We also provide a condition that produces a solution that assigns the whole workload to a single class.

Minimization of Concave Holding Costs in Queueing System

서승범 연세대학교 경영연구소 2020 연세경영연구 Vol.57 No.2

Since the advent of basic  rule, minimization of holding costs has been one of the most fundamental problems in queueing theory. The first results on holding cost minimization was under the linear cost assumption and the more general case of convex costs has been solved with help of queueing approximation method named heavy traffic. Even with many sophisticated solutions on general settings, there is scarce literature that goes beyond convex or linear cost structure. Especially, a holding cost minimization problem with concave cost structure has not been discuessed yet. As far as we know, our work is the first to study concave cost structure in queueing theory. We study how the customers from multiple classes should be prioritizized. We figure out that so-called bang-bang policy is always included in the set of optimal prioritization policies when the costs are concave and that all the optimal solutions to strict concave costs are bang-bang. With this property, we construct a simple and general solution for the concoave cost minimization problem. We also provide a condition that produces a solution that assigns the whole workload to a single class.

An Open Central Server Model based on Fuzzy Queueing System

Jo,Jung Bok,Yang,Hwang Kyu,Lee,Jae Uk 東西大學校 1997 동서논문집 Vol.3 No.1

The purpose of this paper is to combine the ability of fuzzy set to represent more realistic situations with the well-established traditional queueing network model problem. We propose an fuzzification of M/M/1 queueing system. We also apply fuzzy set theory to the open central server network model with the fuzzy queues. Thus, we represent the characteristic and performance of open central server network model based on fuzzy queueing system.

거래자료 기반의 능력계획

최상웅(Choe, Sang-Woong) 한국의사결정학회 2014 의사결정학연구 Vol.22 No.2

탐색적 자료분석 접근법을 이용하여, 높은 다양성으로 대표되는 주문생산 환경의 거래자료에 내포된 의미있는 현상들을 연구하고자 한다. 사용되는 거래자료에는 2년간(2012년-2013년)의 주문내역이 기록되어 있다. 주문내역은 주문도착시점, 주문인도시점, 주문명세(제품모델, 해당 모델의 총중량, 주문수량) 그리고 자체생산 혹은 하청생산 여부 등으로 구성된다. 생산능력 부족에 대처하는 방법들 중 하나인 하청생산을 함께 운영하는 주문생산시스템을 대상으로, 거래자료를 기반으로 하여 생산능력계획에 대한 대기행렬이론 관점을 소개하고자 한다. 이 논문에서는, 대기행렬을 직접 관찰하는 것이 아니라, 단지 거래자료에서 추론함으로써, 대기행렬 통계량(대표값)을 도출하는 방법을 제안한다. We use Exploratory Data Analysis to study transactional data, which contain significant phenomena in Make-to-Order environments characterized by high variety. The transactional data we obtained contain records of order, including its arrival time, departure time, arrival mode(product model, gross weight, quantity) and type of acceptance(in-housing or subcontracting) over a period of two years(2012-2013). We seek to introduce a queueing-theory perspective of a data-based production capacity planning in Make-to-Order systems, where subcontracting could be an important way of overcoming capacity shortages. In this paper, we propose a way to derive the queue statistics only by drawing inferences from the transactional data, not by observing the queue.

Determination of Adequate Distance for Driveway Corner Clearance

권성대,박제진 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.8

Direct vehicle access at site is usually restricted in situations where the driveway corner clearance (DCC) is designated, as per the District Unit Planning Guidelines. Currently, no clear installation standard for the DCC in Korea exists; thus, vehicles are allowed access regardless of the clearance between the driveway and the intersection. When driveways are located adjacent to the intersection, frequent conflicts between vehicles on minor and major roads occur. This results in problems with traffic communication and safety, necessitating a reasonable design. Therefore, in this study, DCCs were classified into upstream driveway corner clearance (UDCC) and downstream driveway corner clearance (DDCC), and algorithms and scenarios for calculating the appropriate DCC distance were proposed. DDCC was calculated from the traffic volume entering the rightmost lane of the DDCC from among the 12 intersection directions by applying optimized signal phase sequence and car-following theory. The DDCC results demonstrated that at least one vehicle in the driveway can exit to the rightmost lane on the roadway at 9.22 m. Two vehicles can exit at 32.15 m, and three vehicles can exit at 67.54 m. UDCC was calculated by considering its geometry, the traffic volume, queue length, and the 8.45 m additional distance from the driveway. Therefore, as traffic volume increased, the queue length and queue clearance time of the queue increased. The calculated DCC distance proposed in this study can contribute to establishing design standards in the future when establishing guidelines for district unit planning.

대기행렬이론을 이용한 기술기반 셀프서비스의 최적운영모델 개발

조재형,강태영 한국인터넷전자상거래학회 2018 인터넷전자상거래연구 Vol.18 No.3

Recently, as the 4th Industrial Revolution is rapidly progressing in the world, Self-Service Technology equipment is increasing in various industry fields. Therefore, we selected Self-Service Gas Station industry among various industry field and studied with the scope of gas station location which is in Busan, Ulsan and Gyeong-Nam in order to develop Optimal Operation Model of Self-Service Technology. As a result, we’ve got optimal economy through the main factors’s relationship that affect Self-Service Technology through queueing theory. Price discounts have a positive impact on the number of customers and the waiting time of the service has a negative impact on the numbers of customers. In addition, the number of visiting customers has a positive impact on the waiting time of the service. Next, the number of the gas stands affects adversely waiting time of the service. Also, the employee working hours have a bad influence on the waiting time of the service. Overall, it is showed that price discounts, the waiting time of the service, the number of the gas stands, the employee working hours contribute to Optimal Model by providing Self-Service Technology for Optimal Operation. The result of this study makes Optimal Operation Model through customer participation in Self-Service theoretically and it can be applied to various Self-Service industry field and is possible to operate optimally.

대기행렬이론을 이용한 수요응답형 대중교통 서비스의 최적 차량 대수 산정에 관한 연구 : 인천 영종도 사례를 중심으로

박준수,김진희,이재형 대한교통학회 2022 대한교통학회지 Vol.40 No.6

최근 수요응답형 대중교통 서비스는 전통적인 대중교통 노선의 배차 간격이 크거나 아예 존재하지 않는 경우 또는 첨두시간에 집중되는 수요 처리를 보조하기 위한 도심형 교통수단으로 주목받고 있다. 하지만 무분별한 차량의 도입은 도로 위 혼잡을 증가시키며, 수요응답형 대중교통 서비스의 고질적인 문제인 서비스 운영비용을 증가시킨다. 따라서 본 연구는 대기행렬이론을 이용한 분석 모델로 수요응답형 대중교통 서비스의 최적 차량 대수를 산정하고 이에 따른 서비스 수준을 분석하였다. 이를 위하여 인천 영종도에서 실제 운행된 I-MOD의 시간대별 수요량 및 서비스 수준을 기초자료로 사용하였다. 모델 검증을 위해 실제 서비스에 성공한 수요를 기준으로 최적 차량 대수를 산정한 결과 실제 운행 대수와 매우 유사하였다. 발생한 모든 수요를 처리하기 위해서는 평균 재차 인원 5명을 기준으로 평일에는 17대, 주말에는 11대의 차량이 필요하며, 배정 대기시간과 탑승 대기시간은 각각 4.4, 8.8분으로 분석되었다. 분석 결과를 바탕으로 서비스 운영정책과 시간대별 차량 관리방안을 제안하였다. 승객의 총 대기시간의 감소를 위해 호출자의 풀을 적정량 유지하여 배정 대기시간을 조정하는 것이 적절하다. 평균 재차 인원의 경우 높게 설정할수록 최적 차량 대수는 적어지지만, 승객들의 총 통행시간이 증가하므로 수요량과 목표 서비스 수준에 맞게 조정할 필요가 있다. 최적 차량 대수는 수요량에 따라 변화하므로 시간대별로 운행하는 차량 대수를 조정하여 운영비용을 감소시키거나 평균 재차 인원을 조정하여 서비스 수준을 증가시킬 수 있다. 본 연구는 수요응답형 대중교통 서비스의 도입에 있어서 최적 서비스 설계 및 시간대별 운영정책을 위한 기초자료로 활용될 수 있다.

Generalized analytical expressions for end-to-end throughput of IEEE 802.11 string-topology multi-hop networks

Sanada, Kosuke,Komuro, Nobuyoshi,Li, Zhetao,Pei, Tingrui,Choi, Young-June,Sekiya, Hiroo Elsevier 2018 AD HOC NETWORKS Vol.70 No.-

<P><B>Abstract</B></P> <P>It is an effective approach for comprehending network performance is to develop a mathematical model because complex relationship between system parameters and performance can be obtained explicitly. This paper presents generalized analytical expressions for end-to-end throughput of IEEE 802.11 string-topology multi-hop networks. For obtaining expressions, a relationship between the durations of the backoff-timer (BT) decrements and frame transmission is expressed by integrating modified Bianchi’s Markov-chain model and airtime expression. Additionally, the buffer queueing of each node is expressed by applying the queueing theory. The analytical expressions obtained in this paper provide end-to-end throughput for any hop number, any frame length, and any offered load, including most of analytical expressions presented in previous papers. The analytical results agree with simulation results quantitatively, which shows the verifications of the analytical expressions.</P>

Analysis on the Operation of a Charging Station with Battery Energy Storage System

Lei Zhu,Yongjian Pu 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

Fossil oil, as the main energy of transportation, is destined to be exhausted. The electrification of transportation is a sustainable solution to the energy crisis, since electric power could be acquired from the inexhaustible sun, wind and water. Among all the problems that hinder the development of Electric Vehicle (EV) industry, charging issue might be the most prominent one. In this paper, the service process of a charging station with Battery Energy Storage System (BESS) is analyzed by means of Cramér – Lundberg model which has been intensively utilized in ruin theory. The service quality is proposed in two dimensions: the service efficiency and the service reliability. The arrival rate and State of Charge (SOC) upon arrival are derived from 2009 National Household Travel Survey (NHTS). The simulations are performed to show how the service quality is determined by the system parameters such as the number of servers, the service rate, the initial capacity, the charge rate and the maximum waiting time. At last, the economic analysis of the system is conducted and the best combination of the system parameters are given.