• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.162-170
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• 2012

We propose a new priority discipline called the strict T-preemptive priority discipline, and derive the waiting time distributions of each class in the strict T-preemptive priority M/G/1 queue. Using this queueing analysis, we evaluate the performance of an opportunistic spectrum access in cognitive radio networks, where a communication channel is divided into time slots, a licensed primary user is assigned to one channel, and multiple unlicensed secondary users may opportunistically exploit time slots unused by the primary user. We also present a numerical example of the analysis of the opportunistic spectrum access where the arrival rates and service times distributions of each users are identical.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.135-139
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• 2014

In a connection-oriented packet switching network, the data communication starts after a virtual circuit is established between source and destination. The virtual circuit establishment time includes the queue waiting times in the direction from source to destination and the other way around. We use this two-way queueing delay to evaluate scheduling policies of a packet switching processor through simulation studies. In this letter, we also suggest user testing functions for the packet switching processor to manage virtual circuits. By detecting error causes, the user testing helps the packet switching processor provide reliable connection-oriented services.

• Korean Institute of Interior Design Journal
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• v.23 no.5
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• pp.174-182
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• 2014

As patients prefer large scale hospitals recently, the interior design of general hospitals are conspicuously improving. In the past, most patients visit hospitals to get treatment on diseases; however, recently patients visiting hospitals for the early prevention of disease is rapidly increasing. Accordingly, contemporary hospitals should meet the wish of patients who want to get medical service in more clean and comfortable environment. The existing studies on hospital interior design were mostly limited on analyzing the functionality of each space; however, studies on the interior design of common use space, which is open to all hospital users, are required now. Accordingly, this study classified the common use space in contemporary general hospitals into lobby space, corridor space, waiting space and resting space. The interior design characteristics of each space were classified into; connectivity with external environment, level change by void, introduction of natural elements, dynamics of space and variety of color. Then a case analysis was done by selecting 12 common use spaces in overseas general hospitals. According to the analysis result, the interior design characteristics were more conspicuous in the sequence of corridor space, lobby space, resting space and waiting space. The interior design elements such as overall space arrangement and material-finishing were relatively acceptable; however, the aspect of a user's environmental behavior, in other words, the psychological aspect, which can lead a patient to natural healing, was relatively insufficient. It is believed that an in-depth interior design focusing on practical users would enable various spatial behaviors. It is hoped that this study would be a help to the interior design of domestic general hospitals as a guideline.

• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.478-489
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• 2018

In this study, a normative script was designed for service design of coffee shop based on user's current and expected script. 1) Activities contained in current and expected script were identified. 2) High frequency activities were selected from current and expected script. Then they were combined and sorted by scene. 3) Importance of the integrated scenes and activities was assessed. 4) According to certain rules, unnecessary activities were deleted, or excluded as optional activities. Then, the remaining activities were classified by scene and listed in order to complete one normative script. Each activity belonging to each scene became a service encounter. Scenes consisted of 'Entering', 'Settling', 'Ordering', 'Waiting for drinks', 'Receiving drinks', 'Spending time drinking beverages', 'Go to the toilet', and 'Get out'. There were 2 activities in 'Entering', 6 activities in 'Settling', 11 activities in 'Ordering', 2 activities in 'Waiting for drinks', 4 activities in 'Receiving drinks', 6 activities in 'Spending time drinking beverages', 3 activities in 'Go to the toilet', and 4 activities in 'Get out'. Specific points were discussed along with these results, and the significance and limitations of the study were added at the end.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.709-718
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• 2002

Cluster based VOD systems require elaborate load balancing and buffer management techniques in order to ensure real-time display for multiuser concurrently. In this paper, we propose a new load balancing technique based on the dynamic buffer partitioning in cluster based VOD servers. The proposed technique evenly distribute the user requests into each service node according to its available buffer capacity and disk access rate. In each node, the dynamic buffer partitioning technique dynamically partitions the buffer to minimize the average waiting time for the requests that access the same continuous media. The simulation results show that our proposed technique decreases the average waiting time by evenly distributing the user requests compared with the exiting techniques and then increases the throughput in each node. Particularly under the overloaded condition in the cluster server, the simulation probes that the performance of the proposed technique is better two times than the Generalized Interval Caching based technique.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.2
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• pp.44-53
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• 2000

The waiting delays of users are inevitable in this policy since the services are not taken immediately upon requests but upon every scheduling points. An inefficient management of such delays makes an unfair service to users and increases the possibility of higher reneging rates. This paper proposes an adaptive batch scheduling scheme which improves the average waiting time of users requests and reduces the starvation problem of users requesting less popular movies. The proposed scheme selects dynamically multiple videos in given intervals based on the service patterns which reflect the popularity distribution(Zipf-distribution) and resource utilizations. Experimental results of simulations show that the proposed scheme improves about 20-30 percentage of average waiting time and reduces significantly the starving requesters comparing with those of conventional methods such as FCFS and MQL.

• Korean Institute of Interior Design Journal
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• v.25 no.4
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• pp.113-124
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• 2016

This research examines domestic and oversea's barrier-free design guidelines provided exclusively for children and their implementations in the common spaces of the outpatient clinics in two pediatric rehabilitation hospitals in Seoul. Based on literature review, a checklist was developed to compare various barrier-free design guidelines in consideration of children's accessibility in space. In addition, four spatial areas in the outpatient clinics of the two hospitals were investigated based on the checklist. As a result, the domestic and Japanese guidelines were aiming primarily to all user groups regardless of ages. Whereas in other oversea's guidelines, a number of barrier-free design standards exclusive for children were found in the facility items such as handrail, sink, urine, toilet, water fountain, chair, table, shelve, and so on, throughout the indoor waiting and sanitary spaces. Concerning implementations, most of the items in the indoor passage, waiting, and sanitary spaces of the two hospitals were not sufficiently facilitated enough to meet with the barrier-free design standards exclusive for children. As such, it is recommended to review and improve the current domestic barrier-free design guideline to accommodate various physical and spatial needs of children in all age groups and regardless of disability types, in the design of a pediatric rehabilitation hospital in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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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.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.99-105
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• 2010

Because in the amusement park, a number of people use various vehicles facilities complicated arraigned, it needs an effective way to search optimal path to reduce errors in touring a park. Particularly, when choosing a facility, searching a waiting time-based path as well as shortest path is important. This paper presents a path recommendation system which minimizes total park tour time based on tour distance and waiting time through GPS and wireless internet. This system can also recommend customized tour path based on the characteristics of user members as well as a simple shortest path.

• Journal of the Korean Society for Library and Information Science
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• v.51 no.2
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• pp.237-253
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• 2017

There are many systematic approaches to manage Interlibrary loan (ILL) efficiently. In this paper, we propose an operating method reducing user-waiting in ILL. Users are usually informed to wait around two to three days in a regional ILL service. The reason of the waiting is that there is inefficiency in running material-delivery vehicles. A mixed integer programming is employed to resolve this issue. It provides an optimal vehicle-route maximizing material-deliveries subject to time availability. We used an actual data of a regional ILL system to provide optimal vehicle routes under different time settings.