• 경영과학
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• 제25권2호
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• pp.57-71
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• 2008

We study factors that affect consumers' switching behaviors among service providers in Korean mobile telecommunications service market. For empirical analysis, quarterly time series data from the first quarter of 2004 through the second quarter of 2007 were used. We chose the number of switchers to each mobile service provider in each quarter as dependent variables. Independent variables include acquisition costs per subscriber, which play the role of subsidy to mobile handset, switching costs, time trend, structural change effect, and waiting demand effects. Through the empirical analysis, we found that each provider's churn-in customers are affected by different factors. Specifically, the number of churn-in customers into SK Telecom is explained mainly by SK Telecom's customer acquisition costs and waiting demand from KTF, while the number of customers switching into KTF is better explained by switching costs from the previous service provider and waiting demand from SK Telecom. Those who chose LG Telecom as their new provider, on the other hand, were mainly attracted by LG Telecom's high subscriber acquisition cost.

• Spatial Information Research
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• 제22권5호
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• pp.65-75
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• 2014

버스 배차간격은 승객의 대기시간 및 차내 혼잡도 등 서비스 수준에 직접적인 영향을 미치고 간접적으로는 버스 운행비용 및 이용자의 교통수단 선택에 영향을 미치는 중요한 요소이다. 대부분의 선행연구에서 버스 배차간격은 첨두시와 비첨두시 구간 통행량을 기반으로 시간대별 수요의 차이만을 반영하고 있다. 이러한 방식의 배차계획하에서는 세분화된 시간적 수요의 차이까지 고려하지 못하므로 승객들의 대기시간 비용이 증가하게 되는 요인이 될 수 있다. 또한, 승객의 승차패턴은 노선, 도로, 정류장의 공간적 배치 특성에 따라 다를 수 있으므로 버스 승객들의 시공간적 수요분포 특성과 변화를 고려한 배차간격 조절에 관한 연구가 필요하다. 본 연구에서는 교통카드 데이터에서 획득한 승객 탑승정보를 바탕으로 정책적 대기시간 제약과 운행 대수 제약조건 및 노선 특성을 반영하여 승객들의 대기시간을 최소화하는 방향으로 배차간격을 조절하는 알고리즘을 제안하였다. 개발 알고리즘의 활용성 검증을 위해 서울시 간선노선 중 143번 노선에 적용한 결과, 승객 대기시간 감축비용을 계산하였을 때 비용절감 효과는 일일 기준 약 600,000원에 이르는 것으로 나타났다. 따라서 개발 알고리즘의 적용 노선을 확장할 경우 버스 승객의 편익 증진에 이바지할 것으로 기대된다.

• 한국멀티미디어학회논문지
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• 제23권3호
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• pp.460-467
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• 2020

The medical service, accompanied by various disease and disease of modern people, must collect various information about patients through various tests, and demand continued to increase. As a result, interest in waiting time for medical services is rising, and various studies are underway to reduce waiting time. However, medical procedure is complex and diverse in the procedure of the services need to be conducted for each procedure. In this study, we are going to propose ways to improve the waiting time of the test procedures that are basically experienced by outpatients through the simulation experimental method. Based on the actual measurement data, the Arena Simulation program was used to implement the hospital's ophthalmic examination model and alternative model. Through this analysis, the waiting time of the examination procedure, the size of the queue, and density of the waiting room were analyzed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권3호
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• pp.919-940
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• 2012

Video on Demand (VOD) is a multimedia service which allows a remote user to select and then view video at his convenience at any time he wants, which makes the VOD become an important technology for many applications. Numerous periodic VOD broadcasting protocols have been proposed to support a large number of receivers. Broadcasting is an efficient transmission scheme to provide on-demand service for very popular movies. This paper proposes a new broadcasting scheme called Popularity Cushion Staggered Broadcasting (PCSB). The proposed scheme improves the Periodic Broadcasting (PB) protocols in the latest mobile VOD system, which is called MobiVoD system. It also, reduces the maximum waiting time of the mobile node, by partitioning the $1^{st}$ segment of the whole video and storing it in the Local Media Forwarder (LMF) exactly in the Pool of RAM (PoR), and then transmitting them when the mobile nodes miss the $1^{st}$ broadcasted segment. The results show that the PCSB is more efficient and better than the all types of broadcasting and caching techniques in the MobiVoD system. Furthermore, these results exhibits that system performance is stable under high dynamics of the system and the viewer's waiting time are less than the previous system.

• 한국정보처리학회논문지
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• 제6권10호
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• pp.2790-2796
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• 1999

In video-on-demand systems, the I.O bandwidth of video servers is the critical resource which contributes to increase in latency. Several approaches: bridging, piggybacking are used to reduce the I/O demand on the video server through sharing. Batching delays the requests for the different videos for a batching window so that more requests for the same video arriving during the current batching window may be served using the same stream. In this paper, we propose an adaptive reservation-based batching policy which dynamically reserves video server capacity for popoular videos according to video server loads. The performance of the proposed policy is evaluated through a simulation, and is compared with simple batching and static reservation-based batching policies. As the result, we know that the adaptive reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching polices.

• 한국조경학회지
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• 제27권4호
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• pp.122-130
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• 1999

The main purpose of this project is to improve the funeral and grave culture which has brought about many social problems, and to fix the crematory culture as the future funeral ceremony in our country. In this study, we first investigated the actual condition of cremation culture. Second, we survey three representative crematorium as an object of study and investigated similar sample buildings in Japan, we analyzed the problem of existing crematorium. Finally, we arranged the basics to approach the space program and design criteria of this project. 1. The entrance of vehicles has been commonly concentrated to the opening time of crematorium. therefore, Peak time has come out as circulation of cremation and waiting time is increasing, also it is difficult to manage the congestion normally. 2. The whole problem of crematorium is poor environment, inferior buildings, noise, unsatisfactory ventilation and privacy, insufficient convenience facilities. 3. The user demand on the crematorium facilities is a private family room for waiting area, a farewell room for family members in a direct line, an outdoor rest area, and the various service facilities, and so on. 4. For improvement of the funeral and grave culture, it is necessary that crematorium is not a hatred facilities, as the conversion of consciousness, and to new shape of charnel as it wore family tomb.

• KEPCO Journal on Electric Power and Energy
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• 제6권1호
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• pp.59-64
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• 2020

Scheduling of electric vehicles and optimizing for charging waiting time have been critical. Meanwhile, it is challengeable to exploit the fluctuating data from electric vehicles in real-time. We introduce an optimal routing algorithm and a simulator with electric vehicles obeying the Poisson distribution of the observed information about time, space and energy-demand. Electric vehicle routing is updated in every cycle even it is already set. Also, we suggest an electric vehicle routing algorithm for minimizing total trip time, considering a threshold of the waiting time. Total trip time and charging waiting time are decreased 34.3% and 86.4% respectively, compared to the previous algorithm. It can be applied to the information service of charging stations and utilized as a reservation service.

• 대한교통학회지
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• 제14권1호
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• pp.69-80
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• 1996

In most cities, travel demand is distributed along long corridors and its destinations tend to concentrate in a central business district. For this kind of many-to-one or one-to-many travel demand pattern, a zonal operation of buses can be an efficient bus operation technique in which a long bus-demand corridor is divided into service zones and each service zone is provided with its own bus route connecting the service zone and single destination separately. This paper develops models of the total transportation costs for a single-zone operation and 2-zonal operation of buses for a long demand corridor with single destination in terms of various cost parameters, demand density, bus operation speeds, and location of the boundary between two service zones. In this study the total transportation cost is assumed to consist of the bus operation cost, passenger waiting cost and passenger travel time cost. It was proved that a zonal operation of buses can be more efficient than a single-zone operation for certain circumstances of the system and an boundary condition between two operation techniques was obtained. Also, several case studies were performed for various values of the cost parameters.

• 한국ITS학회 논문지
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• 제21권1호
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• pp.17-34
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• 2022

본 논문은 수요대응형 모빌리티 이용객의 출발지와 목적지까지 최적 경로 산정을 위한 동적정류장 배정 모형을 개발하였다. 여기서 최적화를 위한 변수로는, 운영자 측면에서 버스통행시간과 이용자 측면에서 서비스 이용 시 추가로 소요되는 정류장까지 도보시간 및 대기시간, 우회시간을 사용하였다. 미국 캘리포니아주 애너하임과 주변 도시를 포함하는 네트워크를 대상으로 승객이 예약한 시종점에서 접근 가능한 동적정류장 리스트를 산정하고 K-means 클러스터링 기법을 이용하여 시종점 그룹들을 각기 차량에 배정하였다. 버스통행시간과 이용자 추가소요시간을 최소화하는 동적정류장 위치 및 버스노선 결정을 위한 모형을 개발하고 다목적 최적화를 위해 NSGA-III 알고리즘을 적용하였다. 최종적으로, 모델의 효용성을 평가하기 위해 이용자 추가소요시간 간의 변수를 조정하여 7개의 시나리오를 설정하였고 이를 통해 목적함수의 타당성을 분석하였다. 그 결과, 운영자 측면에서는 버스통행시간과 승객 대기시간만 고려한 시나리오가, 이용자 측면에서는 버스통행시간, 도보시간, 우회시간을 적용한 시나리오가 가장 우수하였다.

• 해양환경안전학회지
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• 제25권5호
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• pp.519-526
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• 2019

본 연구는 대기정박지의 신설 및 조정이 필요한 항만을 위해 정박지의 적정 용량을 산정하기 위한 방법론을 제시하고, 이를 진해만 내 항만과 부산에 적용하여 국내 주요 항만의 정박지 용량과 비교 분석하여 적용에 무리가 없는지 검토하기 위한 목적이 있다. 이를 위해 항만을 이용하는 선박의 총톤수 용량과 동시 정박 가능 용량의 개념을 정의하고 정박지 용량지수를 계산하여 대상항만을 위한 적정 정박지 용량을 산정하는데 이용하였다. 그 결과 진해만 내 항만의 정박지 용량지수는 0.89로 산출되었으며, 대기정박지 신설을 위한 적정 정박지 용량지수는 6.0 수준으로 분석되었다. 본 연구에서 제시한 정박지 용량지수의 개념을 정박지 설계 기준으로 반영할 경우 정박지를 이용하는 선박의 안전, 정박지 안전성 및 항만의 효율적인 운영에 도움을 줄 수 있을 것으로 판단된다.