• Journal of KIISE
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• v.41 no.9
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• pp.715-727
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• 2014

The number of subscribers in 4th generation mobile system has been increased rapidly. Along with that, preserving subscribers' privacy has become a hot issue. To prevent users' location from being revealed publicly is important more than ever. In this paper, we first show that the privacy-related problem exists in user authentication procedure in 4th generation mobile system, especially LTE. Then, we suggest an attack model which allows an adversary to trace a user, i.e. he has an ability to determine whether the user is in his observation area. Such collecting subscribers' location by an unauthorized third party may yield severe privacy problem. To keep users' privacy intact, we propose a modified authentication protocol in LTE. Our scheme has low computational overhead and strong secrecy so that both the security and efficiency are achieved. Finally, we prove that our scheme is secure by using the automatic verification tool ProVerif.

• Journal of Communications and Networks
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• v.11 no.6
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• pp.589-598
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• 2009

In wireless sensor networks, a node that reports information gathered from adjacent assets should relay packets appropriately so that its location context is kept private, and thereby helping ensure the security of the assets that are being monitored. Unfortunately, existing routing methods that counter the local eavesdropping-based tracing deal with a single asset, and most of them suffer from the packet-delivery latency as they prefer to take a separate path of many hops for each packet being sent. In this paper, we propose a routing method, greedy perimeter stateless routing-based source-location privacy with crew size w (GSLP-w), that enhances location privacy of the packet-originating node (i.e., active source) in the presence of multiple assets. GSLP-w is a hybrid method, in which the next-hop node is chosen in one of four modes, namely greedy, random, perimeter, and retreat modes. Random forwarding brings the path diversity, while greedy forwarding refrains from taking an excessively long path and leads to convergence to the destination. Perimeter routing makes detours that avoid the nodes near assets so that they cannot be located by an adversary tracing up the route path. We study the performance of GSLP-w with respect to crew size w (the number of packets being sent per path) and the number of sources. GSLP-w is compared with phantom routing-single path (PR-SP), which is a notable routing method for source-location privacy and our simulation results show that improvements from the point of the ratio of safety period and delivery latency become significant as the number of source nodes increases.

• Convergence Security Journal
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• v.6 no.4
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• pp.141-151
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• 2006

The destructive power of cyber threat arrived to until the phase which it threatens to direct and seriously in national security undergoes an important national institutuin hacking event of 2004 and Internet paralysis accidents of 2003. 1. 25. So Cyber terror and Cyber warfare is not the hypothetical enemy situation. It is more actual security situation and identify as magnification of warfare concept of incapacitation national important ability include military command system of the adversary, communication, energy, finance and transportation system. consequently, with the progress of cyber threat, it is necessary that looking at a number of general plan to make up for the weak points in cyber warfare operation system. Thus, the focus of this study is to examine new ways of developing a comprehensive cyber security management system.

• Archives of Plastic Surgery
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• v.38 no.1
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• pp.113-116
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• 2011

Purpose: Many fingertip injuries are associated with nail injury and it is hard to repair to original shape due to its unique characteristic. Mucosal graft is used for a defect of the nail bed injury. Hereby, we introduce a DAP flap and buccal mucosal graft, with which we could reduce the defect size of the injured fingertip and donor site morbidity at the same time, without any need for harvesting additional skin from other part of hand. Also, mucosal graft makes good cosmetic and functional outcome of nail. Methods: This method was performed in a 56-year-old man with fingertip injury on dorsal side of left thumb due to electrical saw. First, DAP flap was performed on the injured finger to reduce the size of the defect of fingertip and cover the bone exposure. Second, nail bed part of the DAP flap was de-epithelized and buccal mucosal graft was done from left side of intraoral cavity wall. Results: Flap and graft survived without any necrosis but some nail bed could not be covered with flap due to insufficient flap size. All wounds healed well and did not present any severe adversary symptoms. Conclusion: DAP flap with mucosal graft is an effective method that we can easily apply in reconstruction of fingertip injury. We suggest that the combination of the two procedures makes good functional and cosmetic outcome compared to the usual manner, especially in cases of nail bed injury without distal phalanx bone defect.

• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.101-110
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• 2011

A smart grid networks delivers electricity from suppliers to consumers using digital technology with two-way communications to control appliances at consumers' homes to save energy, reduce cost and increase reliability and transparency. Security is critically important for smart grid networks that are usually used for the electric power network and IT environments that are opened to attacks, such as, eavesdroping, replay attacks of abnormal messages, forgery of the messages to name a few. ZigBee has emerged as a strong contender for smart grid networks. ZigBee is used for low data rate and low power wireless network applications. To deploy smart grid networks, the collected information requires protection from an adversary over the network in many cases. The security mechanism should be provided for collecting the information over the network. However, the ZigBee protocol has some security weaknesses. In this paper, these weaknesses are discussed and a method to improve security aspect of the ZigBee protocol is presented along with a comparison of the message complexity of the proposed security protocol with that of the current ZigBee protocol.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.131-138
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• 2020

Malware is generally recognized as a computer program that penetrates another computer system and causes malicious behavior intended by the developer. In cyberspace, it is also used as a cyber weapon to attack adversary. The most important factor that a malware must have as a cyber weapon is that it must achieve its intended purpose before being detected by the other's detection system. It requires a lot of time and expertise to create a single malware to avoid the other's detection system. We propose the framework that automatically generates variant malware when a binary code type malware is input using the DCM technique. In this framework, the sample malware was automatically converted into variant malware, and it was confirmed that this variant malware was not detected in the signature-based malware detection system.

• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.27-34
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• 2008

Wireless sensor networks are comprised of sensor nodes with resource-constrained hardware. Nodes in the sensor network without adequate protection may be compromised by adversaries. Such compromised nodes are vulnerable to the attacks like false reports injection attacks and false data injection attacks on legitimate reports. In false report injection attacks, an adversary injects false report into the network with the goal of deceiving the sink or the depletion of the finite amount of energy in a battery powered network. In false data injection attacks on legitimate reports, the attacker may inject a false data for every legitimate report. To address such attacks, the probabilistic voting-based filtering scheme (PVFS) has been proposed by Li and Wu. However, each cluster head in PVFS needs additional transmission device. Therefore, this paper proposes a fuzzy logic-based false report detection method (FRD) to mitigate the threat of these attacks. FRD employs the statistical en-route filtering scheme as a basis and improves upon it. We demonstrate that FRD is efficient with respect to the security it provides, and allows a tradeoff between security and energy consumption, as shown in the simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.867-875
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• 2014

Rapid development of internet service is enabling internet banking services in anywhere and anytime. However, service access through internet can be exposed to adversary easily. To prevent, current service providers execute authentication process with user's identification and password. However, majority of users use short and simple password and do not periodically change their password. As a result of this, user's password could be exposed to attacker's brute force attack. In this paper, we presented enhanced password system which guarantee higher security even though users do not change their current password. The method uses additional secret information to replace real password periodically without replacement of real password.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.951-958
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• 2017

In an attack context, the adversary wants to retrieve the message from the intercepted noisy bit stream without any prior knowledge of the channel codes used. The process of finding out the code parameters such as code length, dimension, and generator, for this purpose, is called the blind recognition of channel codes or the reconstruction of channel codes. In this paper, we suggest an improved algorithm of the blind recovery of rate k/n convolutional encoders in a noisy environment. The suggested algorithm improves the existing algorithm by Marazin, et. al. by evaluating the threshold value through the estimation of the channel error probability of the BSC. By applying the soft decision method by Shaojing, et. al., we considerably enhance the success rate of the channel reconstruction.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.6
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• pp.425-429
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• 2009

Recently, Chen et al.'s proposed mutual authentication scheme based on the quadratic resiidue, finding the squaring root problem, for avoiding exhaustive search on the server. But, if a malicious reader sends same random value, the tag is traced by an adversary. Moreover, there is realization problem because of its limited ability to compute squaring and hash function. In this paper, we analyze Chen et al.'s scheme and its weakness. Furthermore we present an improved mutual authentication scheme based on the quadratic residue which solves the tracing problem by generating random value on the tag and uses only squaring. We also make the scheme satisfy to forward secrecy without updating and synchronizing and avoid exhaustive search.