• Journal of KIISE:Computer Systems and Theory
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• v.30 no.1
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• pp.22-32
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• 2003

Many of multimedia applications in distributed environments generate the packets which have the real-time characteristics for continuous audio/video data and transmit them according to the teal-time task scheduling theories. In this paper, we model the traffic for continuous media in the distributed multimedia applications based on the high-bandwidth networks and introduce the PDMA algorithm which is the hard real-time task scheduling theory for guaranteeing QoS requested by the clients. Furthermore, we propose the admission control to control the new request not to interfere the current services for maintaining the high quality of services of the applications. Since the proposed admission control is sufficient for the PDMA algorithm, the PDMA algorithm is always able to find the feasible schedule for the set of messages which satisfies it. Therefore, if the set of messages including the new request to generate the new traffic. Otherwise, it rejects the new request. In final, we present the simulation results for showing that the scheduling with the proposed admission control is of practical use.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.1033-1036
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• 2013

A study about collision resolution is needed because huge file, video and multimedia information are transmitted to wireless LAN. CSMA/CR protocol guarantees fairness, but doesn't consider QoS. To practicalize CSMA/CR protocol in saturation fully-connected single hop network environments, this paper proposes method of collision compensation. previous CSMA/CR protocol chooses CR Slot only considering fairness, but this paper chooses front CR Slot for compensation of collision to station experiencing collisions. The station transmits jam signal and has channel priority of transmission. So transmitting efficiency and successful transmission probability rise. This proposed simple method can offer benefit to station experiencing collisions without additional hardware cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.135-143
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• 2008

In this paper, we propose a QoS guaranteed and energy-efficient transmission scheme for Wireless Personal Area Networks (WPANs), which operate in conjunction with contention-based access protocols such as CSMA/CA. Energy consumption is one of the most important issues in WPAN systems, because WPAN devices are often required to operate under limited battery capacity. Furthermore, if the WPAN adopts a contention-based medium access protocol, the energy consumption problem becomes even more critical due to the collisions caused by independent channel access trials. Therefore, in this paper, we propose an algorithm that selects the optimum fragment size, modulation level, and transmission power, in order to minimize the energy consumption and guaranteethe QoS (Quality of Service) requirements, simultaneously. Our simulation results show that the proposed algorithm has better performance than the previous ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6B
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• pp.338-348
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• 2005

Currently, IEEE 802.11 Wireless LAN (WLAN) is rising as the most popular means for the broadband wireless access network. In this thesis, we propose a QoS(Quality of Service)-Oriented mechanism using handshaking method of scanning phase in IEEE 802.11 handoff. In conventional process for handoff, the major criterion to select the best AP(Access Point) among candidates is normally based on the RSS(Received Signal Strength), which does not always make the selected network guarantee the maximum achievable performance. Even though the link quality with a neighboring AP is excellent, the AP may not be a good candidate to handoff to simply because MAC(Medium Access Control) protocol of IEEE 802.11 standard is contention-based such as CSMA/CA. Therefore, if we apply network level information to AP selection criteria, we can achieve better handoff efficiency rather than before. The analysis and simulation results applied to our new mechanism show clearly better performance than AP selection based on traditional handoff method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.573-577
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• 2005

Recently there are increasing needs for Internet and various kinds of contents. These traffics for various contents need more amount of data to provide high-quality information and require various QoS depending on the characteristics of contents. However, current Internet service supports BE (Best Effort) service only, therefore IntServ (Integrated Service) scheme and DiffServ (Differentiated Service) scheme are represented to support QoS in IP layer. Moreover, while wireless Internet is getting popular, MAC(Medium Access Control)is also becoming important. This is due to the fact that wireless access, resource allocation and packet scheduling, which are done in another layers before, are performed in MAC layer in many new wireless systems. This paper describes new scheme that provides QoS taking into account the traffic characteristics over Mobile IPv6 network based on IEEE 802.11e EDCF and evaluates the performance through computer simulation.

• The Journal of the Korea Contents Association
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• v.18 no.5
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• pp.71-81
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• 2018

In korea, the infantile abandonment is increasing recently. In this situation, present study aims to analyze german "confidential birth service"(vertrauliche Geburt) and to find out implications for korean practice. the results of the study are as follows. "confidential birthservice" is centered on pregnancy counseling center. Through this service, pregnant women in crisis are assured of their anonymity and can safely bring baby into the world. After the child is 16 years old, they can learn about personal information of their biological mother. These "confidential birth service" has received positive evaluation in terms of accessibility, sustainability and reliability of services, linkage and cooperation among agencies, quality of counseling and publicity. Implication for Korean pratice include the provision of legal and institutional devices for "confidential birth services", the establishment of implementing agencies, cooperation with related organizations, and the strengthening of the capacity of practitioners, as well as suggestions in the field of counseling and public relations.

• Journal of Advanced Navigation Technology
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• v.10 no.1
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• pp.63-69
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• 2006

Recently there are increasing needs for Internet and various kinds of contents. These traffics for various contents need more amount of data to provide high-quality information and require various QoS depending on the characteristics of contents. However, current Internet service supports BE (Best Effort) service only, therefore IntServ (Integrated Service) scheme and DiffServ (Differentiated Service) scheme are represented to support QoS in IP layer. Moreover, while wireless Internet is getting popular, MAC(Medium Access Control) is also becoming important. This is due to the fact that wireless access, resource allocation and packet scheduling, which are done in another layers before, are performed in MAC layer in many new wireless systems. This paper describes new scheme that provides QoS taking into account the traffic characteristics over Mobile IPv6 network based on IEEE 802.11e EDCF and evaluates the performance through computer simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.4
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• pp.1-10
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• 2004

In NGNs(Next Generation Networks), It is necessary for Integrated management of resource and information to satisfy high-quality users'demands, such as stable speed, guarantee of high level service and service requirement in various fields. In relation to this, technology for efficiently using limited resources is becoming interesting things more and more. Therefore policy of network service is dealt essentially. Recently, DEN(Directory Enabled Network)-based personalization service is user-dependent services in NGNs, and integrated management and efficient use of limited resources. Also, PBNM(Policy-Based Network Management) is new technology defined and applied by policies of communication service environments and users on demand. Subsequently to study on how to optimizing the PBNM is of great importance. In this paper, we propose a technology of the PBNM based on DEN standardized in DMTF(Distributed Management Task Force).

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.193-202
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• 1999

A promising telecommunication system so called IMT-2000 is forecasted to cover almost 50 percent of telecommunication services, which will be provided in the beginning of the year 2000. The system offers high quality service such as data, image, and video as well as voice. UPT, which offers the personal mobility, is recognized as an important service because we can bind a variety of wire or wireless networks as single number. This paper discusses the design of IMT-2000 MSC based on AIN and UPT service in the MSC. First, we propose the system structure of the IMP-2000 MSC, as a platform of UPT service implementation. Based on this, we define main functions and its blocks of the IMP-2000 MSC. Third, we present the structure of SSF and Its operational mechanism to support the IN services such as UPT. Finally, we present the detail UPT service implementation for the IMP-2000 MSC through the design of UPT call flows between software blocks, which are the minimum units, within the IMPt-2000 MSC.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.113-120
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• 2006

This thesis deals with solutions such as coverage area extension, reduction of the shadow region and performance enhancement of handover caused by structural modification of WiBro network. The More far the distance of RAS(Radio Access Station) and SS(Subscriber Station) is in micro cell, the more bad the quality of channel environment becomes owing to radio interference. Consequently, it causes the deterioration of the throughput and also the deterioration of communication quality in many sides. In fact, most users of WiBro are located in the region, the QPSK region which is bad in point of channel quality. It brings the service complaint by user. We select RS(relay station) to solve the matter caused by channel environment in this cell, and extend coverage and improve the performance of handover call blocking.