• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.113-121
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• 2007

Commonly, in the Sensor Network that composed with multiple nodes uses Ad-hoc protocol to communicate each other. Each sensed data packets are collected by base node and processed by Host PC. But the Ad-hoc protocol is too vulnerable to Sinkhole attack, where the intruder attracts surrounding nodes with unfaithful routing information, and then performs selective forwarding or changes the data passing through it. The Sinkhole attack increases overhead over the network and boosts energy consumption speed to decrease network's life time. Since the other attacks can be easily adopted through sinkhole attack, the countermeasure must be considered carefully. In this paper, we proposed the Hop-depth algorithm that detects intruder in Sinkhole attack and colluded nodes. First, the proposed algorithm makes list of suspected nodes and identifies the real intruder in the suspected node list through the Hop-depth count value. And recalculates colluder's path information to find the real intruder. We evaluated the performance of the proposed algorithm using NS2. We compared and analyzed the success ratio of finding real intruder, false positive ratio, false negative ratio, and energy consumption.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.120-130
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• 2009

In recent years, many mobile wireless communication devices and applications have been deployed on the planet. The mobile multi-hop wireless network models appeared to provide means to access to networks where few infrastructure exists. However, the mobile multi-hop wireless networks have weaker points in attacks and intrusions than the wired and one-hop wireless networks. In this paper, the secure routing issues in most mobile multi-hop wireless network models are surveyed in depth. The state-of-the-art technologies and research activities are explained. Finally, the issues and technologies for the secure routing specific to a maritime network model are sufficiently discussed as conclusions.

• Fashion & Textile Research Journal
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• v.24 no.5
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• pp.493-504
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• 2022

This study aims to gain a deeper understanding of the fashion styles of underground rappers in China and South Korea. Due to rappers' fashion influence on modern fashion trends, research on rapper fashion has been conducted steadily in the field of apparel. Qualitative research methodologies including literature research and in-depth interviews were the primary techniques used to solve the research questions. In-depth interviews were conducted with 10 Chinese underground rappers and 10 Korean underground rappers to reveal and explore their fashion style and view of fashion. As a result, the participants' fashion styles were categorized into four styles: authentic hip-hop fashion style, popularized hip-hop fashion style, easy sports casual style, and trendy street style. Rappers from both countries consider that their identity as rappers can be demonstrated through their hip-hop fashion style. The influence of hip-hop culture and the popularity of rap music differs between China and Korea. It affects not only the rapper's musical characteristics, but also their fashion style. While Korean underground rappers' fashions style is trendier, Chinese underground rappers' fashions style displays stronger characteristics of hip-hop fashion. Due to the public's negative view of rappers, some Korean underground rappers intentionally try to hide their identity by wearing a fashion style that differs from the authentic rapper image. Understanding the fashion styles of underground rappers in Korea and China is expected to assist in predicting future hip-hop culture and rapper fashion trends.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.448-450
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• 2005

A ubiquitous network allows all users to access and exchange information of any kind freely at any time, from anywhere, and from any appliance through the use of broadband and mobile access. Bluetooth commincation can provide the missing wireless extension to the heterogeneous network, allowing a more ubiquitous access. In this point of view, the BT specifications define ways for which each BT device can set up multiple connections with neighboring devices to communicate in a multi-hop fashion. this paper provides insights on the Bluetooth technology and on some limitations of the scatternet formations. so that, we describe a new multi-hop routing protocol for the establishment of scatternets. this protocol defines rules for forming a multi-hop topology in two phases. the first phase, topology discovery, concerns the discovery of the node's depth from a root node initiating inquiry process. the second phase forms scatternet topology based on the result of topology discovery.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.201-209
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• 2020

The graph data structure is popular because it can intuitively represent real-world knowledge. Graph databases have attracted attention in academia and industry because they can be used to maintain graph data and allow users to mine knowledge. Mining reachability relationships between two nodes in a graph, termed reachability query processing, is an important functionality of graph databases. Online traversals, such as the breadth-first and depth-first search, are inefficient in processing reachability queries when dealing with large-scale graphs. Labeling schemes have been proposed to overcome these disadvantages. The state-of-the-art is the 2-hop labeling scheme: each node has in and out labels containing reachable node IDs as integers. Unfortunately, existing 2-hop labeling schemes generate huge 2-hop label sizes because they only consider local features, such as degrees. In this paper, we propose a more efficient 2-hop label size reduction approach. We consider the topological sort index, which is a global feature. A linear combination is suggested for utilizing both local and global features. We conduct experiments over real-world and synthetic directed acyclic graph datasets and show that the proposed approach generates smaller labels than existing approaches.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.5
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• pp.623-634
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• 1999

The purpose of this study is to explore the culture of clothing of subgroups among adolescents by residence. In this research informants were selected by selective sampling and ethnographic methods such as field work depth interviews and open-ended descriptions were employed to interpret their culture of clothing. The results were followed. First our adolescents enjoyed the popular song as leisure and these popular culture was their inspiration source of style. Second adolescents were grouping the Kang-Bouk and the adolescents group preferred the style of popular singers and the Kang-Nam adolescents group preferred the musical competence of singers and specific type particularly Hip-Hop style. And in acception pattern of fashion style the Kang-Bouk groups accepted the recent fashion style continuously and wanted to be striking while the Kang-Nam groups accepted the various Hip-Hop styles and sought to comfort and suitability of that style. Third to consider the connotations of marketing the Kan-Bouk groups shopped on the street perceived as fashionable among peer groups and sought to the lower price but the Kang-Nam groups used the shops selling their original ip-Hop style without regard to the price and sites. Although there existed a two years' difference between the first and the second research(1996-1998) subgroups among adolescents according to the residence have had their own culture of clothing constantly. And a segmentation tendency by clothing behavior within the same adolescent generation is revealed more visibly.

• Journal of Information Processing Systems
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• v.13 no.6
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• pp.1436-1458
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• 2017

Quorum-based algorithms are widely used for solving several problems in mobile ad hoc networks (MANET) and wireless sensor networks (WSN). Several quorum-based protocols are proposed for multi-hop ad hoc networks that each one has its pros and cons. Quorum-based protocol (QEC or QPS) is the first study in the asynchronous sleep scheduling protocols. At the time, most of the proposed protocols were non-adaptive ones. But nowadays, adaptive quorum-based protocols have gained increasing attention, because we need protocols which can change their quorum size adaptively with network conditions. In this paper, we first introduce the most popular quorum systems and explain quorum system properties and its performance criteria. Then, we present a comparative and comprehensive survey of the non-adaptive and adaptive quorum-based protocols which are subsequently discussed in depth. We also present the comparison of different quorum systems in terms of the expected quorum overlap size (EQOS) and active ratio. Finally, we summarize the pros and cons of current adaptive and non-adaptive quorum-based protocols.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.4
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• pp.406-412
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• 2001

IP address lookup is to determine the next hop destination of an incoming packet in the router. The address lookup is a major bottleneck in high performance router due to the increased routing table sizes, increased traffic, higher speed links, and the migration to 128 bits IPv6 addresses. IP lookup time is dependent on data structure of lookup table and search scheme. In this paper, we propose a new approach to build a lookup table that satisfies the memory constraint. The design of lookup table is formulated as an optimization problem. The objective is to minimize average depth from the root node for lookup. We assume that the frequencies with which prefixes are accessed are known and the data structure is level compressed trie with branching factor $\kappa$ at the root and binary at all other nodes. Thus, the problem is to determine the branching factor k at the root node such that the average depth is minimized. A heuristic procedure is proposed to solve the problem. Experimental results show that the lookup table based on the proposed heuristic has better average and the worst-case depth for lookup.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.396-400
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• 2005

In this paper, we propose an efficient full mesh topology aggregation method in PNNI networks. The proposed scheme can search multi-links efficiently using the depth priority method based on hop count instead of searching the all links. To evaluate performance of the proposed scheme, we compare/analyze the current method with the proposed scheme with respect to call success rate, access time and crankback rate. The result is that the proposed scheme is better than the current scheme in performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.677-685
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• 2009

There are a number of studies that propose transmission power control algorithms in wireless sensor networks. However, these algorithms have a lot of overhead in the initialization phase since a number of packets have to be transmitted to determine the optimal transmission power level. This paper proposes the transmission power control technique considering the shortest-path to minimize the hop-count without the occurrence of any power control messages. We applied the proposed technique on tree-based network component implemented on TinyOS. And we evaluated the performance including transmission energy and average network depth with 21 motes. Compared to before, the proposed technique reduces about 24.7% of the average electric current on transmitting. As a result of considering the shortest-path, the hop-count considering the shortest-path was about 41% less than a normal network.