• 한국정보처리학회논문지
• /
• 제7권2S호
• /
• pp.656-665
• /
• 2000

A critical issue in the performance of a video-on-demand system is the I/O bandwidth required in order to satisfy client requests. Several approaches: batching, bridging, piggybacking are used ot reduce the I/O demand on the video server through sharing. Piggybacking is the policy for altering display rates of requests in progress fro the same object, for the purpose of merging their corresponding I/O streams into a single stream, which can serve the entire group of merged requests. In this paper, we propose a new policy called an adaptive reservation-based piggybacking that dynamically reserves the I/O stream capacity of video server for popular videos according to video server loads to immediately schedule the requests for popular videos. The performance of the proposed policy is evaluated through simulations, and is compared with that of simple piggybacking. As the result, we know that the adaptive reservation-based piggybacking provides better service probability, average waiting time and percentages saving in frames than simple piggybacking.

• 대한디지털의료영상학회논문지
• /
• 제16권1호
• /
• pp.61-67
• /
• 2014

The demand of cyclotron for PET (positron emission tomography) has rapidly grown as the more use of PET or PET-CT equipment requires the increased amount of radioactive isotopes for clinical positron emission. While research on failure statistics of medical equipment used in medical centers has continued to be done, the analysis and study on failure statistics of cyclotron have rarely been conducted. However, the growing demand shows the urgency of systematical management guideline and countermeasures for device failure to minimize any supply delay of radiopharmaceuticals occurred by such failure and complains from waiting patients for PET-CT diagnosis. Therefore, this study aims to analyze the failure report from Minitrace equipped in cyclotron which is owned by the department of nuclear medicine at Yeungnam University Medical Center and draws on the data to build effective management system for cyclotron.

• 교육시설 논문지
• /
• 제27권5호
• /
• pp.24-31
• /
• 2020

This study proposed an effective improvement direction for the education and welfare supporting facilities and equipment sectors to guarantee the right of disabled students to study in university. To derive high-demand items, the value engineering quality model technique was conducted on the students who majoring in architecture and the disabled students. The high-demand items for the education and welfare supporting facilities and equipment was detailed by interviews with the disabled students. Especially, anti-skid floor material, spacious access space for electric wheelchair, efficient operation system for elevator and cafeteria waiting time are strongly demanded for the disabled students. Based on this research, universities can make efficient investments and improvements in the education and welfare supporting facilities and equipment sectors for disabled students.

• 한국정보통신학회논문지
• /
• 제9권8호
• /
• pp.1847-1854
• /
• 2005

기존 VoD 시스템의 멀티캐스트 방법은 사용자의 요청수가 증가함에 따라 시스템 부하가 증가하게 되어 시스템의 성능이 떨어지게 된다. 본 논문에서는 사용자들이 빈번하게 요청하는 인기비디오에 대한 정보를 프록시 서버에 저장 관리하여, 사용자들의 비디오 요청 시 발생하는 네트워크의 사용과 서버의 부하를 줄이는 방법에 대해 연구하였다. 본 논문에서는 효율적인 VoD 서비스를 위해 멀터 프록시(Multi-Proxies)들을 관리하는 Interchange Agent(IA)를 구축하였다. 이를 위해, 멀티캐스팅 기법을 이용하여 사용자의 동일 비디오 요청을 하나로 묶어 처리하여 네트워크 및 서버의 부하를 줄고, 자신의 리스트를 이용하여 멀티프록시 캐시의 내용을 중복 없이 관리하여 시스템 효율을 높이며, 스위칭 기능을 통하여 사용자가 요청한 비디오가 연결된 다른 프록시에 존재하면 이를 스위칭 채널을 통해 즉시 전송하여 실시간 서비스의 효율을 높이고, 각 프록시 캐시의 임시저장장소와 카운터를 이용하여 사용자의 인기비디오 순위 변경 시, 캐시의 내용을 변경하여 그 흐름을 반영하도록 하였다.

• 인터넷정보학회논문지
• /
• 제21권5호
• /
• pp.39-48
• /
• 2020

Recently, the study and development of environment-friendly energy technique have increased in worldwide due to environmental pollution and energy resources problems. In vehicle industry, the development of electric vehicle(EV) is now on progress, and also, many other governments support the study and development and make an effort for EV to become widely available. In addition, though they strive to construct the EV infra such as a charge station for EV, the techniques related to managing charge demand and peak power are not enough. The standard of EV communication has been already established as ISO/IEC 15118, however, most of implemented EVs and EV charge stations do not support any communication between each of them. In this paper, an improved slow charge scheme for non-communication EVs is proposed and designed by using predicting charge demand. The proposed scheme consists of distributed charge model and charge demand prediction. The distributed charge model is designed to manage to distribute charge power depending on available charge power and charge demand. The charge demand prediction is designed to be used in the distributed charge model. The proposed scheme is based on the collected data which were from EV slow charge station in business building during the past 1 year. The system-level simulation results show that the waiting time of EV and the charge fee of the proposed scheme are better than those of the conventional scheme.

• 전기학회논문지
• /
• 제60권12호
• /
• pp.2254-2259
• /
• 2011

The introduction of Personal Rapid Transit (PRT) has been widely discussed in the Korean transportation research field. However, there is no robust criterion to derive the throughput of cars and passengers at PRT stations, which plays a primary role in determining the overall capacity of PRT systems. The present study provided a methodology to rigorously compute the capacity for simple-serial PRT stations with a single platform, considering three decisive factors, i.e., the demand level of incoming cars and outgoing passengers, the station structure, and the operation strategy. A micro-level simulator was developed for the analysis of station capacity. And, by using this, station capacities were presented for various combinations of the decisive factors. In particular, the relationship between capacity and station structure was investigated in detail. Station structure is represented by the numbers of platform berths, input queue berths, and output queue berths. Moreover, both waive rate and waiting time, which represent the level of passenger service, were taken into account when the station throughput was computed.

• 보건행정학회지
• /
• 제8권1호
• /
• pp.183-202
• /
• 1998

This study is to investigate patient's choice of health care and the demand for Korean traditional medicine care in rural areas in 1995. It tried to evaluate the effect of out-of-pocket expenditure, travel time, and waiting time on improving care-seeking and substituting clinical medicine for pharmacy care and Korean traditional medicine care in rural areas. The statistical model of this study is conditional logit to estimate effects of choice-specific and individual-specific characteristics on the choice of type of services. This study used, as explanatory variables, average out-of-pocket payment, travel time, and waiting time of services required to use the services. The model was empirically tested using data from 1995 Korean National Health Survery. The results showed that rural Koreans responded to out-of pocket payment and travel time. Increases of out-of-pocket payment and travel time decreased the probability to choose care in rural Korea. Rural Koreans were more likely to seek care than others with low out-of-pocket payment and travel time. The probability of choosing Korean traditional medicine were higher among the members of the households with higher education level and older persons, while they were lower in the households with large family than others compared with the probabilities of choosing public health facilities. The result of this study implies that policy on use of health care in rural Korea can be focused in managing travel time and out-of-pocket payment.

• 산업경영시스템학회지
• /
• 제39권3호
• /
• pp.147-155
• /
• 2016

Industry 4.0's goal is the 'Smart Factory' that integrates and controls production process, procurement, distribution and service based on the fundamental technology such as internet of the things, cyber physical system, sensor, etc. Basic requirement for successful promotion of this Industry 4.0 is the large supply of semiconductor. However, company I who produces dicing blades has difficulty to meet the increasing demand and has hard time to increase revenue because its raw material includes high price diamond, and requires very complex and sensitive process for production. Therefore, this study is focused on understanding the problems and presenting optimal plan to increase productivity of dicing blade manufacturing processes. We carried out a study as follows to accomplish the above purposes. First, previous researches were investigated. Second, the bottlenecks in manufacturing processes were identified using simulation tool (Arena 14.3). Third, we calculate investment amount according to added equipments purchase and perform economic analysis according to cost and sales increase. Finally, we derive optimum plan for productivity improvement and analyze its expected effect. To summarize these results as follows : First, daily average blade production volume can be increased two times from 60 ea. to 120 ea. by performing mixing job in the day before. Second, work flow can be smoother due to reduced waiting time if more machines are added to improve setting process. It was found that average waiting time of 23 minutes can be reduced to around 9 minutes from current process. Third, it was found through simulation that the whole processing line can compose smoother production line by performing mixing process in advance, and add setting and sintering machines. In the course of this study, it was found that adding more machines to reduce waiting time is not the best alternative.

• 대한교통학회지
• /
• 제21권5호
• /
• pp.19-29
• /
• 2003

본 연구의 목적은 주차정보제공에 따른 개인의 주차장 선택행태를 분석하고 이를 주차장 대기행렬 시뮬레이션으로 구현하여 주차정보제공에 의한 도심주차 개선효과를 분석하는 것이다. 이를 위해 서울시 도심지역 주차장 이용자를 대상으로 선호의식(Stated Preference)조사를 실시하여 주차장 이용실태와 주차정보제공의 변수가 포함된 주차선택 모형을 구축하였고 시뮬레이션 방법을 이용하여 주차정보제공 효과분석을 실시하였다. 즉, 주차효용함수, 차량도착간격, 차량주차시간, 각 주차장의 주차공급면수와 동적으로 변화하는 대기시간 및 주차장의 여유상황을 이용하여 정보의 효과를 분석하였다. 본 연구결과 주차장 상황에 대한 정보제공이 혼잡한 주차장의 차량분산효과 및 대기시간 감소 효과가 있는 것으로 나타나 주차정보를 제공하는 주차안내정보시스템의 도입시 효과가 큰 것으로 판명되었다. 이러한 효과는 주차수요가 증가함에 따라 더욱 크게 나타나 주차수요가 많은 도심지역에서 주차정보시스템의 필요성 및 기대효과가 클 것으로 예상되었다. 이러한 차량분산 및 대기시간 감소효과는 정보이용율 40∼50%이상을 유지하는 것이 효과적이며, 주차장이 용량상태에 이르는 혼잡상황에서는 대기시간과 같은 구체적인 정보가 유용한 것으로 나타났다.

• 한국실내디자인학회논문집
• /
• 제13권5호
• /
• pp.133-142
• /
• 2004

Recently, the Korean medical system changed with diversification & specialization and the field of medical service is also specialized in these days. And healing environment is proposed as a general concept in the hospital architecture. There is a trend that a establishment of women's hospital is increasing as specialized type. In difference from general hospital, they are providing specialized and integrated services in response to the women's disease and demand. Particularly, Outpatient department space in women's hospital has been changed in terms of area, shape and program. However, there used to be not enough research efforts of responding these changes. This study includes the Outpatient department of s women's hospital in the form of small and medium sized building over a certain level in Korea. And the methods of the study adopted the theoric examination based concept and features of women's hospital, the abstraction of distinctions in the Outpatient department through the analysis of the drawing, and the analysis of distinctions in the Outpatient department of women's hospital with the structural space classified and the analysis of space relation. Therefore, the purpose of this is to study investigates and analyzes the spatial characteristics of the Outpatient department space in women's hospital through a analysis of case study. To conclude, the space composition can be classified into the entry space, the clinic space for patients, the support space of patients' check-up, the reception and waiting space, the rest and convenience space, and the link space in the Outpatient department of women's hospital. The level space can account for the waiting space type, the clinic office type, the type based on the relation between the waiting room and the clinic office with its features. As a result, the results will be applied for the planning & design for the future women's hospital.