• Journal of Information Processing Systems
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• v.2 no.1
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• pp.48-51
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• 2006

To achieve security in wireless sensor networks (WSN), it is important to be able to encrypt messages sent among sensor nodes. We propose a new cryptographic key management protocol, which is based on the clustering scheme but does not depend on the probabilistic key. The protocol can increase the efficiency to manage keys since, before distributing the keys by bootstrap, the use of public keys shared among nodes can eliminate the processes to send or to receive keys among the sensors. Also, to find any compromised nodes safely on the network, it solves safety problems by applying the functions of a lightweight attack-detection mechanism.

• Journal of Digital Contents Society
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• v.9 no.1
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• pp.33-39
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• 2008

Mobile Ad Hoc Network is easy to be attacked because nodes are distributed not network based infrastructure. Intrusion detection system perceives the trust values of neighboring nodes and receives inspection on local security of nodes and observation ability. This study applied clustering mechanism to reduce overhead in intrusion detection. And, in order to measure the trust values, it associates the trust information cluster head received from member nodes with its own value and evaluates the trust of neighboring nodes. Secure data transmission is received by proposed concept because the trust of nodes on network is achieved accurately.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.66-73
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• 1991

During the growth of macroscopically dislocation-free Czochralski silicon crystal, micro precipitates causing stacking faults in the silicon wafer during the oxidation are formed Thermal history the cryscausing acquire during the growth process is known to be a key factor determining the nucleation of this micro precipitates. In this article, various mechanisms suggested on the formation of microdefects in the silicon crystal are reviewed to secure the nucleation mechanism of the micro precipitates causing OSF whose pattern is normally ring or annular in CZ silicon crytal. B-defects which are known as vacancy clustering are considered to be the heterogeneous nucleation sites for the micro precipitates causing OSF in the CZ silicon crystals.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.2
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• pp.130-139
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• 1995

A hierarchical placement system based on routing region assignment has been developed to increase the probability of routing completion after placement. While most of the existing placement systems attempt to reduce the cell density at the portions where routing density is high, our method is distinguished in that specific routing regions are allocated to secure complete routing where the routing density is greater than the routing capacity. Hierarchy is vuilt by clustering and recursive paritioning, and the initial placement obtained by partitioning at each level is improved by using the region refinement algorithm. After placement at each hierarchical level, global routing is performed and fouting regions are assigned, if routing density is greater than routing capacity, to be considered at the next level of placement. the proposed algorithm has been implemented and applied to place several industrical gate-array circuits. A couple of circuits which cannot be routed by using conventional placement techniques can be completely routed by using our new placement technique with routing region assignment.

• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.329-342
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• 2008

The Sensor Networks have limitations in utilizing energies, developing energy-efficient routing protocol and secure routing protocol are important issues in Sensor Network. In the field of data management, Tributaries and Deltas(TD) which incorporates tree topology and multi-path topology effectively have been suggested to provide efficiency and robustness in data aggregation. And our research rendered hierarchical property to TD and proposed Clustering-based Tributaries-Deltas. Through this new structure, we integrated efficiency and robustness of TD structure and advantages of hierarchical Sensor Network. Clustering-based Tributaries-Deltas was proven to perform better than TD in two situations through our research. The first is when a Base Station (BS) notices received information as wrong and requests the network's sensing data retransmission and aggregation. And the second is when the BS is mobile agent with mobility. In addition, we proposed key establishment mechanism proper for the newly proposed structure which resulted in new Sensor Network structure with improved security and energy efficiency as well. We demonstrated that the new mechanism is more energy-efficient than previous one by analyzing consumed amount of energy, and realized the mechanism on TmoteSKY sensor board using TinyOS 2.0. Through this we proved that the new mechanism could be actually utilized in network design.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.43-52
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• 2006

LRecently, with increasing interest in ubiquitous computing, knowledge discovery method is needed with consideration of the efficiency and the effectiveness of wide range and various forms of data. Spatial Characterization which extends former characterization method with consideration of spatial and non-spatial property enables to find various form of knowledge in spatial region. The previous spatial characterization methods have the problems as follows. Firstly, former study shows the problem that the result of searched knowledge is unable to perform the multiple spatial analysis. Secondly, it is unable to secure the useful knowledge search since it searches the limited spatial region which is allocated by the user. Thus, this study suggests spatial characterization which applies to density based clustering.

• Journal of The Korea Institute of Healthcare Architecture
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• v.28 no.1
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• pp.63-74
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• 2022

Purpose: The purpose of this study is to present an evacuation performance analysis model that can derive vulnerable evacuation spaces with considering the movement behavior as per the elderly groups in the event of a fire in a geriatric hospital. Methods: The evacuation characteristics of geriatric hospital users were investigated through the review of precedent studies. First, the occupant conditions and the evacuation scenario were set to analyze a study target hospital. Then, the evacuation simulation was carried out considering the group types and the density of each group. Finally, an evacuation performance analysis model according to the group type was presented based on the simulation results. Results: The results of this study are as follows: (1) The evacuation performance according to the group type is to be clarified through the suggested study model. (2) It is necessary to secure a ramp or an emergency elevator to distribute the evacuation personnel at the design stage because congestion occurs due to collisions between evacuees on the stairs and delays the evacuation time. (3) It is necessary to consider the evacuation stairs and openings of sufficient size by analyzing the frequency of congestion occurrence and the escape routes of occupants in advance to identify the space where the evacuation flow overlaps. Implications: It is expected that the study result is to be used as primary data for studies that consider the elderly and clustering evacuation behavior in the event of a fire in a geriatric hospital.

• Convergence Security Journal
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• v.9 no.2
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• pp.71-78
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• 2009

It is very difficult to apply previous security protocols to WSNs(Wireless Sensor Networks) directly because WNSs have resource constrained characteristics such as a low computing ability, power, and a low communication band width. In order to overcome the problem, we proposes a secure group communication scheme applicable to WSNs. The proposed scheme is a combined form of the TEEN(Threshold sensitive Energy Efficient sensor Network protocol) clustering based hierarchical routing protocol and security mechanism, and we assume that WSNs are composed of sensor nodes, cluster headers, and base stations. We use both private key and public key cryptographic algorithms to achieve an enhanced security and an efficient key management. In addition, communications among sensor nodes, cluster headers, and base stations are accomplished by a hierarchical tree architecture to reduce power consumption. Therefore, the proposed scheme in this paper is well suited for WSNs since our design can provide not only a more enhanced security but also a lower power consumption in communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.801-807
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• 2013

WSN consists of hundreds to thousands of sensor nodes. In order to solve the problem of energy consumption imbalance cluster head is reelected in every round, while node authentication scheme is utilized for secure communication. However, re-clustering increases the overhead of sensor nodes and during the node authentication phase the frequent AREQ/AREP message exchange also increases the overhead. Therefore, a secure and energy efficient protocol, by which overhead of sensor nodes is reduced and long time communication is achieved, is required for wireless sensor network. In this paper, an energy efficient and reliable IDE-LEACH protocol for WSN is proposed. The proposed protocol is prolongs networks lifetime about average 20% compared to the LEACH-based protocols and all attending nodes in communication form BS authentication consisted of trusted nodes.

• Journal of Technology Innovation
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• v.13 no.1
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• pp.213-246
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• 2005

Despite of the impressive progress made in the Evolutionary techno-economics during the last two decades, there have been very little, if not at all, theoretical advancement in explaining an endogenous mechanism of transforming a technological paradigm within self-perpetuatingstructural dynamics. The question poorly attempted was raised by Schumpeter a century ago in his effort to overcome the well-known 'Walras' trap'. Although there have been increasing number of researchers recently tackling the issue quite seriously from within the Evolutionary school, I see it that radical reconstruction of the basic principle of Evolutionary research framework is urgently needed to solve the century long fundamental question, from evolutionary approach to transformational approach. In the paper, I will show the theoretical feasibility of explaining an endogenous mechanism of paradigm transformation, relying upon the concept of localized dynamics and the concept of morphogenetic structuration. It should be emphasized that there must be aendogenous process of deepening structural Instability generated in the process of economic coordination to secure efficient circular flow. The concept of development bottleneck initiated by the Baumol's cost disease could be regarded as one of the important source of such mechanism. Unfortunately, however, it is a brief conceptual description presented in the paper rather than a comprehensive analytical model, due to the space limitation imposed.