• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권11호
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• pp.2804-2823
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• 2013

Wireless sensor network (WSN) is a promising technology for monitoring physical phenomena at fine-grained spatial and temporal resolution. However, the typical approach of sending each sensed measurement out of the network for detailed spatial analysis of transient physical phenomena may not be an efficient or scalable solution. This paper focuses on in-network physical phenomena detection schemes, particularly the distributed computation of the boundary of physical phenomena (i.e. event), to support energy efficient spatial analysis in wireless sensor networks. In-network processing approach reduces the amount of network traffic and thus achieves network scalability and lifetime longevity. This study investigates the recent advances in distributed event detection based on in-network processing and includes a concise comparison of various existing schemes. These boundary detection schemes identify not only those sensor nodes that lie on the boundary of the physical phenomena but also the interior nodes. This constitutes an event geometry which is a basic building block of many spatial queries. In this paper, we introduce the challenges and opportunities for research in the field of in-network distributed event geometry boundary detection as well as illustrate the current status of research in this field. We also present new areas where the event geometry boundary detection can be of significant importance.

• 전기전자학회논문지
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• 제23권3호
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• pp.941-946
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• 2019

본 논문에서는 LTE(Long Term Evolution) SON(Self Organization Network) 환경에서 PCI(Physical Cell Identification)를 할당하는 방법에 대하여 분석하였다. PCI를 할당하는 방법에 다양한 기법들이 제시되었고 규격에서는 기본적으로 PCI를 할당하는 과정에서 다른 셀과 ID가 '충돌'(Collision) 또는 '혼란'(Confusion)을 일으킬 수 있다는 것을 제시하였다. 따라서 본 논문에서는 LTE 규격에서 제시하는 PCI '충돌', '약한충돌'(Weak Collision) 그리고 '혼란'의 시나리오가 무엇인지 내용을 살펴보았다. 또한, 각 시나리오에 대한 해결 방법으로 셀 중앙적접근과 분산적 접근 방법에 대해 살펴보았다. 논문에서는 최근 연구되고 있는 그래픽 컬러링(Graphic Coloring) 기법에 대한 접근 방법에 대해 살펴보았고 중앙접근적 방법에 대한 전략에 대해 설명하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권5호
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• pp.799-818
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• 2010

In traditional unstructured P2P file sharing network, each peer establishes connections with a certain number of randomly chosen other peers. This would lead to redundant traffic and P2P network partition in mobile ad hoc network (MANET). We propose an approach to construct an efficient unstructured P2P overlay over MANET using underlying cluster-based routing (CBRP). One of the peers in the P2P network is used as a root-peer to connect all peers. Each peer maintains connection with physically closer peers such that it can reach the root-peer. The peer constructs a minimum-spanning tree consisting of itself, its directly connected neighbor peers and 2-hop away neighbor peers to remove far away redundant links and to build an overlay closer to the physical network. Due to on-demand nature of inter-cluster routing of CBRP, the positioning algorithm for MANET is used to retrieve the file by a peer from the source peer via shorter path in the physical network. We can show by simulation that our approach performs better in comparison with the existing approach.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.61-64
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• 2003

Technological progress in integrated, low-power, CMOS communication devices and sensors makes a rich design space of networked sensors viable. These sensors can be deeply embedded in the physical world and spread throughout sensor network environment like smart dust. So ubiquitous computing will be come true. SmartDust project is the one of ubiquitous computing approach. It produces TinyOS, mote(mica, mica2, rene2, mica2dot, etc.), NesC, TinyDB, etc. We constructs sensor network test bed and tests to approach sensor network and ubiquitous computing.

• Journal of Communications and Networks
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• 제14권5호
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• pp.554-565
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• 2012

In this paper, we study a cross-layer and end-to-end optimization problem for the integrated wireless and wireline network that consists of one wireline core network and multiple wireless access networks. We consider joint end-to-end flow control/distribution at the transport and network layers and opportunistic scheduling at the data link and physical layers. We formulate a single stochastic optimization problem and solve it by using a dual approach and a stochastic sub-gradient algorithm. The developed algorithm can be implemented in a distributed way, vertically among communication layers and horizontally among all entities in the network, clearly showing what should be done at each layer and each entity and what parameters should be exchanged between layers and between entities. Numerical results show that our cross-layer and end-to-end optimization approach provides more efficient resource allocation than the conventional layered and separated optimization approach.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1991년도 춘계공동학술대회 발표논문 및 초록집; 전북대학교, 전주; 26-27 Apr. 1991
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• pp.464-464
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• 1991

We address the problem of designing a physical CATV network with switched-star topology in which the broadband interactive service is provided. There are two types of decision variables: One is where to place conduit paths, and the other is how many cable units to be installed on each link traversed by an established conduit path. Due to the serious drawback of the conventional approach partitioning the problem into two subproblems, the unified approach handled in one setting is used here to attack the whole problem without dividing into two ones. In this paper, we present a mathematical design model and propose an efficient solution method exploiting the nice structure of it. In addition to this physical design, some results on logical network configuration have also been made. Finally, computaional experiments are conducted to illustrate the efficiency of our design approach.

• 국제물리치료학회지
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• 제10권4호
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• pp.1926-1933
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• 2019

Background: Physical therapy has been widely studied in various fields, however, the academic trends and characteristics has not been systematically analyzed. Semantic network analysis is used as an approach for this study. Objective: To explore academic trends and knowledge system in the physiotherapy research in the Journal of International Academy Physical Therapy (J of IAPTR) Study design : Literature review Method: Semantic network analysis was conducted using the titles of 272 articles published in the Journal of IAPTR from 2010 to 2019. Results: Frequency analysis revealed following most frequently used key words; Stroke (27 times), Balance (21 times), Elder (13 times), Forward head posture (FHP, 11 times), Muscle activity (9 times). The relationship between the presented keywords is divided into six subgroups (FHP and pain, walk and quality, elder and balance, stroke and apoptosis, muscle strength and function) according to their correlation and frequency to be used together. Conclusion: The study is considered to be of help to researchers who want to identify research trends in physiotherapy.

• KIEAE Journal
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• 제10권5호
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• pp.31-41
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• 2010

The direction of Urban regeneration is changing toward holistic regeneration with residents' participation all over the world. While world leading projects in holistic regeneration such as "Ballymun of Ireland" and "Buffalo of U.S.A" appeared, recently in Korea, "Rainbow project" is getting paid attention as a similar example due to its Socio-Physical approach. The purpose of this study is to find the Effect of Socio-Physical Regeneration on Social Network characteristics of Elderly Residents in a public rental apartment. The subjects of the study are elderly residents who have resided since much before the environmental intervention. The research methods is in-depth interview. Specific features of social network included awareness of the physically improved surrounding environment, awareness of and participation in welfare programs, social interactions, identity, and vandalism behavior. As results, most of elderly residents recognized environmental improvement and felt very positive enough to enhance their attachment and pride in their residences. Physical environment changes had a considerable impact on the social network characteristics and also had a strong influence on their relations with community. Considering that permanent public rental housing has been a socially isolated place, it is significant to notice that residents' perception of being excluded and behaviors are changed gradually being influenced by environmental improvement.

• 시스템엔지니어링학술지
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• 제12권2호
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• pp.101-114
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• 2016

A model-based systems engineering (MBSE) approach to implementing hardware-based network cybersecurity controls for APR1400 non-safety data network is presented in this work. The proposed design was developed by implementing packet filtering and deep packet inspection functions to control the unauthorized traffic and malicious contents. Denial-of-Service (DoS) attack was considered as a potential cybersecurity issue that may threaten the data availability and integrity of DCS gateway servers. Logical design architecture was developed to simulate the behavior of functions flow. HDL-based physical architecture was modelled and simulated using Xilinx ISE software to verify the design functionality. For effective modelling process, enhanced function flow block diagrams (EFFBDs) and schematic design based on FPGA technology were together developed and simulated to verify the performance and functional requirements of network security controls. Both logical and physical design architectures verified that hardware-based cybersecurity controls are capable to maintain the data availability and integrity. Further works focus on implementing the schematic design to an FPGA platform to accomplish the design verification and validation processes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권1호
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• pp.157-176
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• 2011

An interest-based P2P constructs the peer connections based on similarities for efficient search of resources. A clustering technique using peer similarities as data is an effective approach to group the most relevant peers. However, the separation of groups produced from clustering lowers the scalability of a P2P network. Moreover, the interest-based approach is only concerned with user-level grouping where topology-awareness on the physical network is not considered. This paper proposes an efficient scalable search for the interest-based P2P system. A scalable multi-ring (SMR) based on fuzzy clustering handles the grouping of relevant peers and the proposed scalable search utilizes the SMR for scalability of peer queries. In forming the multi-ring, a minimized route function is used to determine the shortest route to connect peers on the physical network. Performance evaluation showed that the SMR acquired an accurate peer grouping and improved the connectivity rate of the P2P network. Also, the proposed scalable search was efficient in finding more replicated files throughout the peer network compared to other traditional P2P approaches.