• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.3
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• pp.49-57
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• 2010

We extended a general attack tree to apply cyber attack model for network vulnerability analysis. We defined an extended cyber attack tree (E-CAT) which extends the general attack tree by associating each node of the tree with a transition of attack that could have contributed to the cyber attack. The E-CAT resolved the limitation that a general attack tree can not express complex and sophisticate attacks. Firstly, the Boolean expression can simply express attack scenario with symbols and codes. Secondary, An Attack Generation Probability is used to select attack method in an attack tree. A CONDITION-composition can express new and modified attack transition which a aeneral attack tree can not express. The E-CAT is possible to have attack's flexibility and improve attack success rate when it is applied to cyber attack model.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.9
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• pp.78-85
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• 2008

Piezoelectric materials have been investigated as vibration energy converters to power wireless devices or MEMS devices due to the recent low power requirements of such devices and the advancement in miniaturization technology. Piezoelectric power generation can be an alternative to the traditional power source-battery because of the presence of facile vibration sources in our environment and the potential elimination of the maintenance required for large volume batteries. This paper represents the new power source which supplies energy device node. This system, called "energy harvesting system", with piezo materials scavenges extra energy such as vibration and acceleration from the environment. Then it converts the mechanical energy scavenged to electrical energy for powering device This paper explains the properties of piezo material through theoretical analysis and experiments The developed system provides a solution to overcome the critical problem of making up wireless device networks.

• IE interfaces
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• v.14 no.3
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• pp.318-325
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• 2001

In this paper, we estimate the investment cost for the IMT-2000 services in Korea. The network elements for the IMT-2000 system are drawn out and the required number of base stations(Node-B) is predicted by using the coverage of the base station. With the assumption of the 2-generation mobile communications network configuration, the number of radio network controllers(RNC's) and core network facilities is estimated. We also setup different scenarios by considering the utilization of the transmission facilities between base stations, RNC's and switching systems, and then evaluate the investment cost for each scenario.

• IE interfaces
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• v.23 no.2
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• pp.193-202
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• 2010

The quality of service(QoS) model should be presented with the optimal network design to effectively provide the multimedia data services between users and converged services with mobile or TV in the next-generation Internet. In specific, the method to provide differentiated services for each user is needed in the given Internet node to offer the previously negotiated QoS with the user. In this paper, the performance of the QoS enabling technologies in the differentiated services(DiffServ) network domain is analyzed. The QoS offering model and QoS metrics are presented to analyze the performance of the major scheduling algorithms. Under the real network topology and virtual service scenarios in the university, the NS-2 network simulation based on the discrete-event is performed. The results show that the ratio-based scheduling method is more effective rather than the bandwidth-assignment method.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.397-400
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• 1998

This paper has a dual purpose. First, we consider a relaxation algorithm which seems to be particularly suitable for multicasting routing problems. We show that the algorithm has polynomial complexity. Second, to measure the quality of solutions in comparison to the optimal solutions over a wide range of network sizes for which the computation of the optimal costs is too excessive, we also propose a random graph generation scheme in which an asymptotic lower bound on the expected optimal cost can be computed as a function of network node size.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.249-250
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• 2008

In the field of mobile communications, load balancing between 3GPP LTE and other networks is expected to be an important topic from the perspective of current technical development. The load balancing technique includes the definition of functions and structures needed to incooperate 3G LTE E-Node B and base-stations designed for heterogeneous networks. The major goal attained from this paper is to ensure an algorithm for the mechanism of load balancing and to achieve a technical leading for the next generation mobile network.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.181-188
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• 2001

An XML is an markup language which has been focused on the next generation Web programming language. It easily represents the complex structure of a document, and it is possible to provide the access control over each component of an XML document. An implicit authorization technique means that granting an authorization to a node has effect on granting the same implicit authorization to its all descendants. Therefore, it enhances the time for the authorization grant and reduces the memory required for the authorization information. An authorization technique using an intention type and a authorization replacement solves a redundancy problem and decides whether the access is possible or the authorization conflict occurs at the first attempt.

• Annual Conference on Human and Language Technology
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• 1996.10a
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• pp.424-429
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• 1996

본 논문에는 일반문서를 대상으로 하여 그 문사를 하이퍼텍스트(hypertext)로 자동변환하는 기법을 제안하고자 한다. 자동변환의 과정은 대상 문서에서 키워드(keyword)의 인식, 문서를 노드(node) 단위로 분리, 키워드로부터 노드로의 링크(ink) 생성의 3 단계로 이루어 진다. 기존의 연구에서는 문서에서 노드를 분리하는데 구문적 유사도만을 이용하는데, 본 논문에서는 양질의 하이퍼텍스트를 생성하기 위하여 구문적 유사도(syntactic similarity)뿐만 아니라 의미적 유사도(semantic similarity)를 사용한다. 구문적 유사도는 tf*idf와 벡터 곱(vector product)을 이용하고, 의미적 유사도는 시소러스(thesaurus)와 부분부합(partial match)을 이용하여 계산되어 진다. 또 링크 생성시 잘못된 링크의 생성을 막기 위하여 시소러스를 이용하여 시소러스에 존재하는 용어에 한해서 링크를 생성한다.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.8
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• pp.39-48
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• 1997

The fast redundancy identification is required to perform an efficient test pattern genration. Due to the reconvergent fanouts which make the dependency among objectives and the fault propagation blocking, there may exist redundnat faults in the cirucit. This paper presents the isomorphism identification and the pseudo dominator algorithms which are useful to identify redundant faults in combinational circuits. The isomorphism identification algorithm determines whether mandatory objectives required for fault detection cannot be simultaneously satisfied from primary input assignments or not using binary decision diagrma. The pseudo dominator algorithm determines whether faults propagation is possible or not by considering all paths at a given fanout node. Several experiments using ISCAS 85 benchmark circuits demonstrate the efficiency and practicability of the algorithms.

• Journal of Korea Multimedia Society
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• v.23 no.4
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• pp.517-524
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• 2020

Recently, many researches have been conducted to automatically recognize license plates of vehicles and use the analyzed information to manage stolen vehicles and track the vehicle. However, such a system must eventually be investigated by people through direct monitoring. Therefore, in this paper, the system of tracking a vehicle is implemented by sharing the information analyzed by the vehicle image among cameras registered in the IoT environment to minimize the human intervention. The distance between cameras is indicated by the node and the weight value of the weighted-graph, and the eigenvector centrality is used to select the camera to search. It demonstrates efficiency by comparing the time between analyzing data using weighted graph searching algorithm and analyzing all data stored in databse. Finally, the path of the vehicle is indicated on the map using parsed json data.