• 대한산업공학회지
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• 제27권1호
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• pp.89-94
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• 2001

There are many queueing systems where customers wait for service up to a certain amount of time and leave the system if they are not served during that time. This paper considers a finite capacity multi-server queueing system with Poisson input and Erlang service time, where a customer becomes a lost customer when his service has not begun within an exponential patient time after his arrival. Performance measures such as average queue length, the average number of customers in service, and the proportion of lost customers can be obtained exactly through the proposed numerical solution procedure.

• 한국통신학회논문지
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• 제30권10A호
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• pp.896-905
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• 2005

본 논문에서는 N-채널 SAW(Stop and Wait) ARQ 재전송 기법을 채택하고 있는 HSDPA 시스템에서 HS-DSCH 채널의 성능 향상을 목적으로 선택적 패킷 지연(SPD :Selective Packet Delay) 기법을 제안한다. SPD 기법은 무선 채널 상태에 따라 적응적으로 패킷 전송을 제어하는 방법으로 채널 상태가 나쁜 경우에는 해당 패킷 전송을 일정시간 동안 강제 지연하고 대신에 해당 타임 슬롯을 채널 상태가 양호한 다른 사용자에게 할당해 주는 기법이다. 따라서 제안하는 기법은 버스트 에러 환경에서 연속적인 패킷 손실로 인해 발생하게 되는 긴 재전송 지연을 효과적으로 줄일 수 있는 특징을 가진다. 또한 SPD 기법에 효율적으로 적용될 수 있는 SPD-LDPF(Long Delayed Packet First)와 SPD-DCRR(Deficit Compensated Round Robin)의 두 종류의 패킷 스케줄링 기법을 제안한다. 시뮬레이션 결과, 제안한 기법은 패킷 평균지연 특성, 처리량 성능, 그리고 사용자간 공평성에서 모두 우수한 성능을 보임을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권7호
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• pp.3470-3493
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• 2019

IEEE 802.11s-based infrastructure Wireless Mesh Networks (iWMNs) are envisaged as a promising solution to provide ubiquitous wireless Internet access. The limited network capacity is a problem mainly caused by the medium contention between mesh users and the mesh access points (MAPs), which gets worst when the mesh clients employ the Transmission Control Protocol (TCP). To mitigate this problem, we use wireless network coding (WNC) in the MAPs. The aim of this proposal is to take advantage of the network topology around the MAPs, to alleviate the contention and maximize the use of the network capacity. We evaluate WNC when is used in MAPs. We model the formation of coding opportunities and, using computer simulations, we evaluate the formation of such coding opportunities. The results show that as the users density grows, the coding opportunities increase up to 70%; however, at the same time, the coding delay increments significantly. In order to reduce such delay, we propose to adaptively adjust the time that a packet can wait to catch a coding opportunity in an MAP. We assess the performance of moving-average estimation methods to forecast this adaptive sojourn time. We show that using moving-average estimation methods can significantly decrease the coding delay since they consider the traffic density conditions.

• 한국항만학회지
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• 제14권1호
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• pp.27-35
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• 2000

In Pusan Harbour, new port development projects are implemented such as the Extended Terminal adjacent to the Gamman Terminal, Pusan New Port, the Navy $\bigcirc$$\bigcirc$ piers, etc. which will require new marine traffic environments in the Passage I of Pusan Harbour. Specially, the turning basin of the Extended Terminal adjacent to the Gamman Terminal has been designed to overlay the Passage I of Pusan Harbour, which will interrupt the inbound traffic flow and the results will be worried to decrease the efficiency of port operation. Therefore, this paper will be aimed to evaluate the traffic congestion in the Pusan Passage I due to the opening of new ports within Pusan Harbour in 2006 and 2011 by using computer simulation based the queueing theory.

• 대한디지털의료영상학회논문지
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• 제15권1호
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• pp.39-45
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• 2013

PACS Import external image of the thread of the tasks and duties of hospital revenue and business efficiency falls over time. 500 beds or more medical imaging import work outside of the hospital, most hospitals use a PC, KIOSK, and was used in 15 hospitals where, CD Autoloader where use was the only one. Working hours compared to CD and DVD media to test the results of the Import target PC, KIOSK, CD Autoloader Import spent less time in the order, and also the greater capacity of CD Autoloader four times the PC, KIOSK 2 times Import could be implemented quickly. In addition, the waiting time of the patients was measured using the PC's time to Import, 2011 14.5 minutes and the average patient waiting time, KIOSK and later use CD Autoloader 2012 average patient wait time of 8.25 minutes, 43% of the existing average waiting time was 5.25 minutes to reduce. However, KIOSK case of a patient in a way that directly Import latency time was soon. Import of three ways: in terms of efficiency and excellent CD Autoloader way, the patient waiting time in terms of ease of use and KIOSK was excellent. In addition, with the introduction of CD Autoloader with KIOSK Joint of the items waiting time of patients and patient satisfaction rating is considered to be a major contribution.

• 한국산학기술학회논문지
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• 제17권10호
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• pp.367-372
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• 2016

현대의 스마트 빌딩은 온도, 습도, 소리, 빛, 이동 등 다양한 물리적 정보를 감지해낼 수 있는 센서가 설치돼 있어 인간의 행동을 감지하고 추적하여 의료, 보안, 에너지 절약 등 각종 편의 시설에의 활용이 가능이다. 본 논문은 스마트 빌딩의 센서 기술을 이용하는 효율적인 엘리베이터 스케줄링 시스템을 제안한다. 스케줄링에 사용되는 센서로는 RFID, 비디오 센서, 바닥 센서 등으로 이들 센서는 엘리베이터 사용자의 도착 여부를 엘리베이터 호출 버튼을 누르기 전에 미리 감지하는 역할을 한다. 감지된 정보는 빌딩 네트워크를 통해 엘리베이터 스케줄링 시스템으로 전달되며, 제안하는 스케줄링 시스템은 이러한 정보를 통해 엘리베이터 사용자들을 위한 예약 호출을 생성하여 엘리베이터의 이동 방향과 이동 시간을 효율적으로 제어한다. 제안하는 엘리베이터 스케줄링 시스템의 성능을 평가하기 위해 다양한 워크로드 환경에서 모의 실험을 수행하였다. 그 결과 제안하는 스케줄링 시스템이 전통적인 엘리베이터 시스템보다 평균 대기 시간, 최악 대기 시간, 에너지 소모량 등에서 우수한 성능을 나타냄을 확인하였다.

• 대한교통학회지
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• 제13권4호
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• pp.105-115
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• 1995

This paper deals with an operation concept of "time-transfer of buses", in which buses arrive a transfer center at the same time and allow passengers to transfer to other bus lines, so that passengerscan go anywhere all the timed-transfere buses operate with only one transfer. This timed-transfer bus system is known as an efficient operating technique which can be adopted in an area with sparsely distrubuted bus demand. A model of timed-transfer is estabilished in terms of vaious factors such as the expected(or average) arrival time, distribution of arrival time, timed-transfer cycle, shceduled departure time, etc. It is assumed that the objective of timed-transfer bus system is to minimize the total transfer waiting time. The optimal schedualed arrival time or buffer time(time required to arrive ealy in consideration of delay) is analyzed for a general case and various speicial cases. It was found that the optiaml buffer time is an inverse funcion of the timed-transfer cycl and increases with the cycle time, assumin g that there is a fixed scheduled departure time at the transfer cetner regardless of whether one or more buses fail to arrive before the scheduled departure time. If buses are to wait uhtil all the buses arrive at the transfer center, that is, the transfer departure time is vairable, the optimal scheduled arrival times can be obtained by a mathmatical programming.

• 대한디지털의료영상학회논문지
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• 제13권4호
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• pp.171-175
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• 2011

Server and Pi view management, external image and internal image Copy Import business in PACS room is through the medical assistance. Import and Copy, and in particular the number of cases is increasing the number of import is a fast growing trend. Although the increase in workload With limited human resources to increase business efficiency so Remote system is using PACS room. This remote system will want to evaluate the effectiveness of using the service. Amount of data each 437.5 MB, Copy and Import time is to compare and evaluate sees by use 1 PC. 4 PC, 4 PC+ remote system. The use of the remote system before the January 2010 to June daily average waiting time and the use of the remote system after the January 2011 to June compared to a daily average patient waiting time, evaluate. Using the remote system in January 2011 to June Find out the average remote utilization. The biggest difference on the four copy and eight continued, Were performed two times faster by use 4 PC+ remote system than use 4 PC and four times faster than use 1 PC. Before using the remote system, the daily average wait time is 14.5 minutes after using the daily average 10.2 minutes, waiting time 30% of the existing waiting time was 4.3 minutes, to reduce. Using the remote system in January 2011 to June the average daily number of cases is 107 number and The number of remote and on average 35 cases with 32% in a day remote usage. The use of the remote system to Import, CD Copy and greatly increase the efficiency of their time could be. Hours due to efficiency could also reduce customer waiting time. As a result, the manpower and the use of a remote system over time to maximize efficiency in business hours, work was evaluated by.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.614-620
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• 2011

Railway intelligent transportation systems and related Ministry of Land and rail operating agency's railway informatization planning of information technology, effective through the use of management strategies to establish or run to support the systematic informatization investment that you want to execute work in progress, during and yet the institutional informatization of operations mainly in the form of efficiency is Chinhae. Accordingly, in order to promote the details of the final challenge of providing real-time information and the usefulness of this information collection is clearly for the railway sector by function of the components is necessary to distinguish. In this paper, the details of the plan goals, promoting convenient rail-based real-time information, to promote optimal gohyoeuleul railways, railway safety and comfort, was defined as three. Selection of each goal, because the direction of vision and ITS around the railroad center of road users by highlighting the benefits of the railroad's traffic information center user switching, real-time delivery of information diversity (enhanced content) that can increase the capacity of line train operating systems, enhancing the safety management system introduced in the monitoring system and is a railroad crossing. Because urban railway project in accordance with the goal of decreasing the annual rate of the train support, and the average passenger wait time savings, increased future demand for railway, rail safety, including securing the expected effects may occur.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.857-862
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• 1992

An elevator group supervisory control logic is investigated to supervise multiple elevators, ensuring their efficient operations. In this paper, a predictive fuzzy control logic of group elevator system is developed for coping with multiple control objects and uncertainty of system state. Simulation of this control logic shows considerable improvements of system performance by the reduction of average waiting time and long wait rate.