• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1A
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• pp.30-37
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• 2006

In this paper, we propose a QoS-aware efficient bandwidth re-provisioning scheme in a next generation wireless packet transport network. At the transport network layer, it classifies the traffic of the radio network layer into a real time class and a non-real time class. Using an auto-regressive time-series model and a given packet loss probability, our scheme predicts the needed bandwidth of the non-real time class at every re-provisioning interval. Our scheme increases the system capacity by releasing the unutilized bandwidth of the non-real time traffic class for the real-time traffic class while insuring a controllable upper bound on the packet loss probability of a non-real time traffic class. Through empirical evaluations using the real Internet traffic traces, our scheme is validated that it can increase the bandwidth efficiency while guaranteeing the quality of service requirements of the non-real time traffic class.

• Journal of the Korean Geographical Society
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• v.49 no.5
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• pp.728-746
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• 2014

The purpose of this study is to analyze the influence of the selective migration of young age group and the stage migration which has proceeded through generations, on the transition of fertility and the population growth in the rural and urban in the case of Jeollabuk-do. For this, we use O-D matrix of 20-34 age group, the distribution of that group and women of child bearing age, and vital statistics in 1970-2010. The major findings of this study are as follows. First, the outflows from their birth place are common and dominant features of 20-34 age group in each time. Second, there is the stage migration which preceding generation moved from the rural areas to the cities in Jeollabuk-do and following generation has moved from the cities to Seoul metropolitan area. Third the selective outflow migration of young age group has leaded to reduction of the childbearing population, declining birthrate, aging and natural population decline. Due to the stage migration, these depopulation processes occurred in rural area in the past, and currently it expands to the cities with about 15 years time gap. In fact, there have been the natural population decrease which annual number of deaths exceed that of births from the late 1980s in the most rural areas and in the early 2000s, such a phenomenon has been confirmed also in urban areas. Therefore, this study concludes that the stage migration through generations is one of the crucial factor to the population growth in local cities and also brings out the step-wise population decrease in settlement hierarchies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.210-216
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• 2004

This paper propose a new structure and procedure that provides fast handover for moving users, who are using real-time applications, in next generation IP networks. This paper also show the excellency of proposed scheme with the delay analysis. The analysis shows that the delay of proposed scheme is lower than existing methods, especially in the situation where the delay between MAP and AR is considerable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.6
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• pp.454-472
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• 2013

The development of wireless network technology and the increasing use of wireless networks to mobile users with a variety of wireless network systems has arisen. Wireless sensor networks, they can be nested together, and the need to switch between the network, depending on your needs. Next Generation Wireless Networks(NGWN) gives the mobile user a wide coverage and optimized service etc. Previous hand off management protocol is not enough to secure support of the NGWN application program. Cross-layer Handoff(CLH) protocol technique has been developed to support between and inside networks of handoff management of NGWN. CLH supports mobility management in a wireless network environment and also utilizes mobility speed and handoff signaling delay information to improve the handoff performance ability. For the analysis of handoff performance ability, we analyzed sensitivity of link layer and network layer, therefore, CLH technique is suggested based on this analysis.

• Information and Communications Magazine
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• v.19 no.11
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• pp.85-108
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• 2002

향후 다양한 무선 통신 규격들의 통합 수용을 위한 SDR (Software Defined Radio) 기술이IMT-2000 이후의 4세대 이동 통신 시스템을 위한 핵심 기술로써 심각하게 고려되고 있다. 이에 부응하여 SDR기반의 멀티모드용 통신 시스템을 구성하기 위한 주요 기술로서 디지털 IF 기술에 대한 필요성이 급속도로 고조되고 있는 상황이다. 최근 ABC/DAC 및 범용 디지털 신호처리 소자들의 고속화 및 고성능화로 인해 If (Intermediate Frequency) 대역과 기저대역 신호들 간의 직접 디지털 변환의 구현이 현실화되고 있다. 사용자의 관점에서 국지적으로 상용화되고 있거나 장래에 출현할 다양한 이동 통신 시스템 규격들 및 이에 대해 사업자들에게 할당되는 주파수 대역들이 서로 다른 점을 고려할 때, 이종 시스템 혹은 사업자들에게 할당된 주파수 대역에 구애받지 않고 언제 어디서나 자유롭게 무선 채널을 엑세스하고 또한 특정 채널을 임의로 선택하기 위한 디지털 If기술의 실현이 필수적이다 이러한 SDR기반 디지털 If 기술은 소프트웨어적으로 재구성 가능한 하드웨어 구조를 요구하며, 특정 이동 통신 규격의 물리 계층만을 지원하는 무선 인터페이스가 아닌 다중이동 통신 모드를 지원할 수 있는 유연성이 가미된 채널화 알고리즘이 필요하게 된다. 따라서 디지털 If기술은 무선 인터페이스 처리 부분, 즉 주파수 상 하향 변환 및 채별 선택 조합을 용도에 맞게 단일의 하드웨어 플렛폼 상에서 고속 디지털 신호처리 알고리즘을 기반으로 동작하기 위한 기능을 필연적으로 요구한다. 본 논문에서는 향후 SDR 기반의 기지국 및 단말기 운영 및 구생 모델을 제시하며, 디지털 If에 대한 필요성 및 동작 원리, 그리고 요소 기능들에 대한 구체적인 동작 원리 및 디지털 If와 더불어 활용 가능한 기술에 대하여 논의한다.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.163-170
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• 2007

The next generation communication environment consists of various wireless access networks with distinct features that are configured as an overlay topology. In the network environments, the frequency of hand overs should be minimized and the error propagation should be solved in order to provide high-quality multimedia services to mobile users. Therefore, we propose an performance enhancement approach, based on mSCTP, that provides high quality multimedia services to mobile users by ameliorating the error propagation problem. We utilizes the following four functions: 1) the separation of transmission paths according to the types of frames. 2) retransmission strategy to minimize the loss rate of frames, 3) Foced vertical handover execution by utilizing bicasting, 4) using the stability period in order to reduce the effect of the ping pong phenomenon. The simulation results show that the proposed approach provides seamless multimedia service to mobile users by achieving error resilience.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.48-59
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• 2009

Next generation mobile communication system will have various access networks and provide seamless multimedia data service to mobile nodes. The WiNGS system, one of these access network, has superior RAT(Radio Access Technology) and network connectivity other than previous ones. In this paper, we propose link-layer SR-ARQ between mobile node and WAGW to solve packet re-ordering problem during handover. In the proposed scheme, we apply the adaptive timer at the SR-ARQ sender to reduce unnecessary packet retransmission during handoff and delayed NAK algorithm at the SR-ARQ receiver for delaying NAK response due to temporary out-of-sequenced frames. We evaluate the performance of the proposed scheme by implementing the new SR-ARQ protocol at the link-layer using ns-2 simulator, and show the handover performance is improved greatly by preventing unnecessary retransmission.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.205-218
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• 2012

Mobility management of the mobile nodes and provision of seamless handover is crucial to an efficient support for the global roaming of the mobile nodes in next-generation wireless networks. Mobile IPv6 and mobility management in extended IP layer, which highly depend on traffic characteristics and user mobility models, were proposed by the IETF. Therefore, to evaluate the in-depth performance about these factors is important. Generally, the performance of IPv6-based mobility management protocol is evaluated through simulation. This paper shows the correlation between network parameters and performance metrics through numerical results, which is investigated how influence handoff latency and packet loss. And this paper uses mathematical analysis of the system parameters, such as the subnet residence time, the packet arrival rate and delay in wireless connection through the analytical framework which evaluate the performance of IPv6-based mobility management protocol.

• KOMUNHWA
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• no.70
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• pp.109-132
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• 2007

Taking the Yosu Peninsula where prestige goods were prevalent and more dolmen were excavated and surveyed than other regions as object of the research, this dissertation investigated the hierarchy of dolmen society. The dolmen groups were excavated and surveyed at some 20 positions in Yosu Peninsula Analyzing the number, weight of upper stone, location, the buried relics of dolmen, the hierarchy for each dolmen group can be summarized as follows. It seems that the large group with a lot of dolmen and big upper stone which is located on the plane with stream or on the lower part of hill might be the central group with abundant buried relics. However, the size of individual upper stone does not coincide with buried relics sometimes. Thus, it is required to review the entirety of dolmen group rather than individual upper stone in the relation between the scale of upper stone and buried relics. Then the scale of tomb is proportionate to the prestige goods. Meanwhile, the discrepancy between dolmens can be verified by the difference among upper stone, tomb, burial accessories, etc in the unit dolmen group. Since dolmen is the tomb of some inhabitants in the Bronze Age, the existence of stone coffin tomb with buried bronze sword, jade or stone sword compared to the stone coffin with no relics means that there was powerful representative of one generation even in one kindred group on the basis of wealth or authority. It can be concluded that the upper stone or large tomb or prestige goods among the persons buried in dolmen were fixed as high class, those with relatively small stone coffin with no or scanty burial accessories were fixed as medium class and multitudinous class who were not buried in dolmen were fixed as low class. Therefore, the dolmen society in Yosu Peninsula shows that there was division of class in the unit dolmen group as well as hierarchy in the group.

• Journal of IKEEE
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• v.5 no.1 s.8
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• pp.8-15
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• 2001

This paper remarks IETF based requirements for IP/UDP/RTP header compression issued in 3GPP2 All IP Ad Hoc Meeting and protocol stacks of the next generation mobile station. All IP Network, for real time application such as Voice over IP (VoIP) multimedia services based on 3GPP2 3G cdma2000. Frames for various protocols expected in the All IP network Mobile Station (MS) are explained with several figures including the bit-for-bit notation of header format based on IETF draft of Robust Header Compression Working Group (ROHC). Especially, this paper includes problems of IS-707 Radio Link Protocol (RLP) for header compression which will be expected to modify in All IP network MS's medium access layer to accommodate real time packet data service[1]. And also, since PPP has also many problems in header compression and mobility aspects in MS protocol stacks for 3G cdma2000 packet data network based on Mobile IP (PN-4286)[2], we introduce the problem of solution for header compression of PPP. Finally. we suggest the guidelines for All IP network MS header compression about expected protocol stacks, radio resource efficiency and performance.