• ETRI Journal
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• v.28 no.4
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• pp.537-540
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• 2006

When multiple ZigBee wireless personal area networks (WPANs) are in close proximity to each other, contentions and collisions in transmissions will lead to increased packet delays. However, there is no existing study on how delay performance would be affected in a crowded real-life environment where each person walking down a busy street would be wearing a ZigBee WPAN. This letter studies the use of ZigBee WPANs in such a real-life environment for real-time heart beat monitoring. To be pragmatic, we derived a mobility pattern from the analysis of a real-life video trace. Then, we estimated the delay performance from the video trace by combining data collected from ZigBee experiments. The results show that the 300 ms packet delay requirement will not be met for only 11% of the time. When failure occurs, it will last for an average duration of 1.4 s.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.263-264
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• 2008

고속 무선 PAN(Personal Area Networks)기술은 10m 이내의 짧은 거리에서 고속으로 대용량의 데이터를 전송하기 위한 기술로, 최근 무선 USB(Wireless Universal Serial Bus)나 HDTV(High Definition TV)와 같은 광대역 멀티미디어 응용 시장을 겨냥한 연구가 IEEE 802.15.3과 WiMedia를 중심으로 활발히 진행되고 있다. [1] 본 논문에서는 WiMedia Alliance에서 제안한 Distributed Medium Access Control (D-MAC)에서 다수 스트림의 QoS 요구를 만족시키는 신뢰성 있는 전송을 위해 데이터 시간 슬롯을 효율적으로 할당하는 알고리즘에 대해 연구하고자 한다.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.215-221
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• 2003

It is expected that per-user customized services are widely used in next generation Personal Communication Network. To provide personalized services for each call, per-user service profiles are frequently referenced and signaling traffic is considerably large. Since the service calls are requested from the places where user stays, we can expect that the traffic is localized. In this paper, we propose a new service profile replication scheme, named Follow-Me Replication with local Anchor (FMRA). By replicating user's service profile in a user-specific location area, local anchor of each region, the signaling traffic for call and mobility can be distributed to local network. We compared the performance of the FMRA with two typical schemes: Intelligent Network-based !Central scheme and IMT-2000 based full replication scheme, as we refer it to Follow-Me Replication Unconditional (FMRU). Performance results indicate that FMRA lies between Central and FMRU schemes according to call to mobility ratio, and we identified the efficient ranges of CMR for FMRA depending on the various network parameters.

• ETRI Journal
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• v.28 no.5
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• pp.660-663
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• 2006

In this letter, we propose a frame-size adaptive MAC protocol for high rate wireless personal area networks (WPANs). In the proposed scheme, during communication, frame error rate is periodically reported to a transmitting device and the frame size is changed according to the measured results. Thus, the channel can be more effectively utilized by adapting to variable radio conditions. Analytical results show that this scheme achieves a much higher throughput than a non-frame-size adaptive media access control protocol in high-rate WPANs.

• Asian Journal for Public Opinion Research
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• v.10 no.3
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• pp.178-199
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• 2022

Two surveys for exploring communicative paths toward political participation were conducted with relatively large samples of Americans (N = 1001) and South Koreans (N = 1166). Hierarchical regression modeling of the relationships among demographics, personal networks, news consumption, and cross-cutting discussion and political participation demonstrated mostly commonalities between the two samples, including the interaction between political diversity and Twitter usage for news access but with distinct effect sizes of cross-cutting discussion on political participation. We attribute the differences to the two countries' distinct histories of democracy and culture, and the commonalities to the general relationships between cross-cutting discussion and political participation moderated by strong ties political homogeneity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.497-511
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• 2019

The purpose of this study is to examine the effects of entrepreneurship and personal characteristics on entrepreneurial intention and to analyze what factors influence the entrepreneurial intention through the moderating effects of social networks. So, the survey was conducted on 374 employees in their 30s or older. Descriptive statistics were used to understand the actual state of entrepreneurial intentions, and exploratory factor analysis was conducted to analyze the validity. In addition, a correlation analysis was conducted to identify relationships with variables, finally, a hierarchical regression analysis was performed to identify the effect of moderating social networks in entrepreneurship and personal characteristics. The study found that, firstly, Entrepreneurship was positively correlated with extroversion, achievement desire, self-efficacy, social network, entrepreneurial intention, and negatively correlated with introversion. Second, The extroversion of personal characteristics showed positive correlations with achievement desire, self-efficacy, social network, and entrepreneurial intention and negatively correlated with introversion. Introversion has a negative correlation with achievement desire, self-efficacy, social network, and entrepreneurial intention, and self-efficacy has a positive correlation with social network and entrepreneurship. Third, social networks have been shown to moderate the relationship between personal characteristics and entrepreneurial intention. Reflecting the results from this study, we expect that those preparing for future start-ups will be a meaningful reference to validate their capabilities and start them.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.465-468
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• 2008

Clustering techniques in wireless sensor networks is developed to minimize the energy consumption of node, show the effect that increases the network lifetime. Existing clustering techniques proposed the method that increases the network lifetime equalizing each node's the energy consumption by rotating the role of CH(Cluster Head), but these algorithm did not present the resolution that minimizes the energy consumption of neighboring nodes with sink. In this paper, we propose the clustering algorithm that prolongs the network lifetime by not including a part of nodes in POS(Personal Operating Space) of the sink in a cluster and communicating with sink directly to reduce the energy consumption of CH closed to sink.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.365-368
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• 2008

This paper presents a new concept of IP-based wireless sensor networks and also introduces a routing protocol that is based on clustering for global healthcare information system. Low-power wireless personal area networks (LoWPANs) conform the standard by IEEE 802.15.4-2003 to IPv6 that makes 6lowpan. It characterized by low bit rate, low power, and low cost as well as protocol for wireless connections. The 6lowpan node with biomedical sensor devices fixed on the patient body area network that should be connected to the gateway in personal area network. Each 6lowpan nodes have IP-addresses that would be directly connected to the internet. With the help of IP-address service provider can recognize or analysis patient biomedical data from anywhere on globe by internet service provider equipments such as cell phone, PDA, note book. The system has been evaluated by technical verification, clinical test, user survey and current status of patient. We used NS-2.33 simulator for our prototype and also simulate the routing protocols. The result shows the performance of biomedical data packets in multi-hope routing as well as represents the topology of the networks.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.329-332
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• 2005

In this paper, we describe implementation of personal media gateway (PMG) for applications over BcN networks. PMG is a TV based set-top terminal, which enables transmission of Full D1 high quality video and audio at the speed of maximum 2Mbps. It supports SIP protocol and QoS for the BcN networks. The hardware of the PMG consists of host module, audio/video codec processing module, DTMF module, and remote control I/O module. H.263 and MPEG4 software are implemented in DSP as codec for hi-directional communication and streaming, respectively. G.711 and Ogg-Vorbis are implemented as audio codec. We examined the quality of video using the Video Quality Test Equpment, which was developed by KT Convergence Lab. The experimental results show the video quality of MOS 4.1 and audio quality of MOS 4.3. We expect that PMG will be prospective business models, and create new customer value.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1107-1112
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• 2008

Clustering techniques, which are algorithm to increase the network lifetime in wireless sensor networks, is developed to minimize the energy consumption of nodes. Existing clustering techniques by to increase the network lifetime with equalizing each node's the energy consumption by rotating the role of CH(Cluster Head), but these algorithms did not present the solution that minimizes the energy consumption of neighboring nodes with sink. In this paper, we propose the clustering algorithm that prolongs the network lifetime by not including a part of nodes in POS(Personal Operating Space) of the sink in a cluster and communicating with sink directly to reduce the energy consumption of CH closed to sink.