• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.51-54
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• 2008

PON(Passive Optical Network) is the promising technology applicable to TPS(Triple Play Service). To improve process the packet, MAC(Multiple Access Control) is the most important technology in the PON. The core of MAC is DBA(Dynamic Bandwidth Assignment), it classifies SR-DBA(Status Report DBA) and NSR-DBA(Non Status Report DBA). But GPON DBA is using BPON's DBA, so it's bad in network efficiency. This study develop BR(Borrow-Refund)-DBA for improve network efficiency and prompt process. For take the gauge of performance evaluation, estimate about throughput, fairness and queue delay in SR-DBA and NSR-DBA environment

• Journal of Communications and Networks
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• v.7 no.2
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• pp.115-125
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• 2005

This paper discusses how to effectively design a next-generation wireless communication system that can possibly provide very high data-rate transmissions and versatile quality services. In order to accommodate the sophisticated user requirements and diversified user environments of the next-generation systems, it should be designed to take an efficient and flexible structure for multiple access and resource allocation. In addition, the design should be optimized for cost-effective usage of resources and for efficient operation in a multi-cell environment. As orthogonal frequency division multiple access (OFDMA) has turned out in recent researches to be one of the most promising multiple access techniques that can possibly meet all those requirements through efficient radio spectrum utilization, we take OFDMA as the basic framework in the next-generation wireless communications system design. So, in this paper, we focus on introducing an OFDMA-based downlink system design that employs the techniques of hybrid multiple access (HMA) and frequency group (FG) in conjunction with intra-frequency group averaging (IFGA). The HMA technique combines various multiple access schemes on the basis of OFDMA system, adopting the multiple access scheme that best fits to the given user condition in terms of mobility, service, and environment. The FG concept and IFGA technique help to reduce the feedback overhead of OFDMA system and the other-cell interference (OCI) problem by grouping the sub-carriers based on coherence band-widths and by harmonizing the channel condition and OCI of the grouped sub-carriers.

• The Journal of the Korea Contents Association
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• v.6 no.5
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• pp.1-8
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• 2006

In ubiquitous environments, recommendation service based on multiple contexts is required. The total amount of information is larger due to the greater number of contexts in multiple context environments. This paper proposes a new effective recommendation method adaptive to multiple contexts in ubiquitous environments. A new method of recommendations in multiple context environments is suggested that uses user's preferences and behavior as a weighting factor. This paper describes the recommendation method, scenario and the experimental results. The results verify that the proposed method's recommendation performance is better than other existing method.

• Korean Journal of Human Ecology
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• v.18 no.2
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• pp.363-379
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• 2009

The purpose of this study is to provide a meaningful thought to professionals and administrators of Korea working for Consumer General Education development at their Universities. Also, tips for organizing and meaning Consumer General Education Curriculum effectively are provided. Finally, the study suggests essential elements to improve qualities of Consumer General Education in Korea Universities. This study's method are content analysis through web site and survey. The subjects of this survey were 257 students. The data were collected by questionnaire developed by researcher and analyzed by frequencies, correlation Analysis, One Way Anova, Duncan Test, Factor Analysis, Multiple Regression Analysis. The major findings were as follows: University students's satisfaction level about General Education was low and the needs level about Consumer General Education was high. And the education service quality showed factors to be administrative service element, professor service element, classroom environment element, communication element. And Multiple Regression Analysis on each of the education service quality factors had been significant effects for find out the differences in the degree of satisfaction.

• The Journal of Information Technology
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• v.10 no.4
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• pp.11-26
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• 2007

EDS is a typical convergence service performing convergence between functions owned by multiple SPs. EDS provides users with the relevant information and the communication by the various personal conditional environment. An alternative terminology for events for net- work related applications is 'triggers'-these are assumed to be included in the present description. Events could be defined as any activities which occur within a service avail ability, signals. Events can be managed, for example, as part of a context-aware application. EDS carry out a procedure for processing user's requested information about mobil network-based entities, such as the combination with various applications, such as a LBS (Location Based Service) and area information. In AS (Application Service) network environments, the user has his customized EDS in the network, the EDS automatically connects the appropriate Terminals consistent with a user profile. EDS can also send the collected information to other requesting users by way of event information and using the procedures of combination with other services. The user can record/retrieve the user-related information to from the information base through EDS.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.55-63
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• 1996

In this paper, a multiple-access algorithm for PCN is proposed. The proposed algorithm provides th integrated service of information soruces and can be operated stably in high load state. Given bandwidth is efficiently used for it in the microcell environment. And system performance can be improved through the statistical-multiplexing technque. In order to process the speech signal usually requiring real-tiem processing, we adopt a random access of AlOHA type for th ebasic protocol sturcture and assume the form of ALOHA-reservation. We have analyzed the performance of the proposed algorithm through system throughput and packet delay in the microcell environment.

• Proceedings of the Culinary Society of Korean Academy Conference
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• 2006.08a
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• pp.115-134
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• 2006

This study was conducted during a period from July 4 to 30 to investigate the effect of restaurant environment upon customer's satisfaction and crowdedness awareness. Total 800sets of questionnaire were distributed among major food service corporations. They were 16 restaurants from McDonald, Burger King, Popeyes, KFC, Rits Carlton, Intercontinental, The Westin Chosun, Hilton, Merriot, Outback Steak House, Bennigans, VIPS, Pizza Hut Pul-hyanggi(Scent of grass), Nolboo Co.,, and Our Story, and received 50 see each to hand out to their customers. Out of total 800 sets of questionnaires, 592 sets (74.25% were retrieved and underwent a Multiple Regression Analysis. We found the following results from the study. First among each variable of restaurant environment that had a significant effect on the crowding, 'pTast service' and 'responsiveness to customer complaints' sooted a regression coefficient value 0.381 and 0.325 respectively. Second, among each restaurant environment factor that had a significant effect on crowding, 'quality of facility' sooted the highest regression coefficient value 0.423 with a standard error score 0.1074, fellowed by 'status of waiting', 'overall ambience' and 'service quality' in ascending order. Third, in the analysis of the effect of each environmental factor upon the satisfaction rate, 'status of waiting' showed the highest regression coefficient value 0.3821 with a standard error score 0.4565, followed by 'cleanliness', 'service quality' and 'conveniency', in ascending order.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.524-526
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• 2006

We proposes integrated information system, Service Robot Information System(SRIS), for mobile robot. The system has objectives that can heir efficient management and sharing as support information for mobile service robot like recognition, navigation, manipulation and modeling. This paper introduces the concert and architecture of SRIS. An Implementation is done by using ER based database and CAD modeling which is DXF format. The experimental shows the result of object and environment map matching by SLAM. This system is expected that can help reduce the cost and efforts of information management under multiple mobile robot environment.

• ETRI Journal
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• v.43 no.5
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• pp.932-940
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• 2021

Currently, research on network functions virtualization focuses on using microservices in cloud environments. Previous studies primarily focused on communication between nodes in physical infrastructure. Until now, there is no sufficient research on group key management in virtual environments. The service is composed of microservices that change dynamically according to the virtual service. There are dependencies for microservices on changing the group membership of the service. There is also a high possibility that various security threats, such as data leakage, communication surveillance, and privacy exposure, may occur in interactive communication with microservices. In this study, we propose an ID-based group key exchange (idGKE) mechanism between microservices as one group. idGKE defines the microservices' schemes: group key gen, join group, leave group, and multiple group join. We experiment in a real environment to evaluate the performance of the proposed mechanism. The proposed mechanism ensures an essential requirement for group key management such as secrecy, sustainability, and performance, improving virtual environment security.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.127-137
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• 2015

Various services such as IPTV(Internet Protocol TV), Internet Telephony are provided through multiple ISPs(Internet Service Providers) as ICT technologies are evolving. This paper suggests that the end-to-end Internet service quality evaluation method, which is optimized for domestic environment based on international standards. The end-to-end service quality determines the quality of IPTV and Internet Telephony services and is critical factor for subjective quality as well. As a result, time delay, jitter and packet loss rate are three elements for the quality evaluation. It is also shown that these factors can be predicted with traditional statistical method by sharing minimum amount of information between ISPs.