• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.615-625
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• 2014

Ministry of National Defense, MND, established a "Master Plan of Military Facility" in 2010 based on the defense reform to prepare for future war. It was a plan for consolidating small military facilities into battalion units, reflecting on and preparing for the needs of various changes in defense environment as well as balanced growth of ROK Army, Navy, and Air Force. However, to move forward with "Military Facility Master Plan," current design criteria for military facilities need to be revised to be enacted due to numerous calculation errors in facility footprints because of the absence of a sound facility criteria. Because the future war environment will be changed from Platform basis to Network Centric Warfare basis, Command & Control capability of C4I systems is getting more important. Therefore, Successful mission accomplishment can be secured by convergence of facility and military Information Technology(IT). So, MND should quickly prepare for the operational guidance, design criteria and policy that are suitable for Network Centric Warfare accomplishment, and implement infrastructure of IT and installation of C2 facility in conjunction with consolidation movement of military facilities. In this paper, we propose the defense I3A framework in order to solve this problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.12
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• pp.831-841
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• 2014

The attacker can access the RFID systems illegally because authentication operation on the RFID systems are performed in wireless communication. Authentication methods based on the PUF were presented to defend attacks. Because of Hash and AES, the cost is expensive for the low-cost RFID tag. In this paper, the PUF-based encryption processor and the mutual authentication protocol are proposed for low-cost RFID authentication. The challenge-response pairs (PUF's input and output) are utilized as the authentication key and encrypted by the PUF's characteristics. The encryption method is changed each session and XOR operation with random number is utilized. Therefore, it is difficult for the attacker to analyze challenge-response pairs and attack the systems. In addition, the proposed method with PUF is strong against physical attacks. And the method protects the tag cloning attack by physical attacks because there is no authentication data in the tag. Proposed processor is implemented at low cost with small footprint and low power.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.365-371
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• 2014

Chaos communication system is possible to improve the system security by using chaos signal. Further, it is possible to reduce the possibility of eavesdropping, and have strong characteristics from interference signal and jamming signal. However, BER(Bit Error Rate) performance of chaos system is worse than digital communication system. By this reason, researches in order to improve the BER performance of chaos communication system are being actively studied. In previous studies, we proposed a novel chaos map for BER performance improvement, and called it 'Boss map'. Also, we proposed a novel chaos transceiver for BER performance improvement. However, BER performance is evaluated differently according to delay time in transceiver. Therefore, in order to use Boss map effectively, we should find the optimal delay time in proposed chaos transceiver. In this paper, when Boss map is used, we evaluate BER performance of CDSK(Correlation Delay Shift Keying) system and novel chaos transceiver according to delay time. After evaluation of BER performance according to delay time, we find a delay time that is possible to have best BER performance in CDSK system and novel chaos transceiver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.7
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• pp.479-490
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• 2014

A lower extremity exoskeleton is a robot device that attaches to the lower limbs of the human body to augment or assist with the walking ability of the wearer. In order to improve the wearer's walking ability, the robot senses the wearer's walking locomotion and classifies it into a gait-phase state, after which it drives the appropriate robot motions for each state using its actuators. This paper presents a method by which the robot senses the wearer's locomotion along with a novel classification algorithm which classifies the sensed data as a gait-phase state. The robot determines its control mode using this gait-phase information. If erroneous information is delivered, the robot will fail to improve the walking ability or will bring some discomfort to the wearer. Therefore, it is necessary for the algorithm constantly to classify the correct gait-phase information. However, our device for sensing a human's locomotion has very sensitive characteristics sufficient for it to detect small movements. With only simple logic like a threshold-based classification, it is difficult to deliver the correct information continually. In order to overcome this and provide correct information in a timely manner, a probabilistic gait-phase classification algorithm is proposed. Experimental results demonstrate that the proposed algorithm offers excellent accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.4
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• pp.351-361
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• 2014

Compared to a terrestrial communication, the high BER(Bit Error Ratio) and low channel bandwidth are the major factor of throughput degradation due to characteristics of underwater channel. Therefore, a MAC protocol must be designed to solve this problem in UWASNs(Underwater Acoustic Sensor Networks). MAC protocols for UWASNs can be classified into two major types according to the contention scheme(Contention-free scheme and Contention-based scheme). In large scale of sensor networks, a Contention-based scheme is commonly used due to time-synchronize problem of Contention-free scheme. In the contention-based scheme, Each node contends with neighbor nodes to access network channel by using Back-off algorithm. But a Slot-Time of Back-off algorithm has long delay times which are cause of decrease network throughput. In this paper, we propose a new scheme to solve this problem. The proposed scheme uses variable Slot-Time instead of fixed Slot-Time. Each node measures propagation delay from neighbors which are used by Slot-time. Therefore, Slot-Times of each node are optimized by considering node deployment. Consequently, the wasted-time for Back-off is reduced and network throughput is improved. A new mac protocol performance in throughput and delay is assessed through NS3 and compared with existing MAC protocol(MACA-U). Finally, it was proved that the MAC protocol using the proposed scheme has better performance than existing MAC protocol as a result of comparison.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.4
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• pp.362-369
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• 2014

A railway SCADA system is a control systems that provide the trains with the electricity. A railway SCADA system sends commands to the RTUs(remote terminal unit) and then it gathers status information of the field devices in the RTUs or controls field devices connected with the RTUs. The RTU can controls input output modules directly, gathers the status information of the field devices connected with it, and send the information to the control center. In this way, a railway SCADA system monitors and controls the electricity power for running trains. The cyber attackers may use some vulnerabilities in the railway SCADA system software to attack critical infrastructures. The vulnerabilities might be created in the railway software development process. Therefore it need to detect and remove the vulnerabilities in the control system. In this paper we propose a new control protocol fuzzing method to detect the vulnerabilities in the DNP3 protocol based application running on VxWorks in RTU(Remote Terminal Unit) that is a component of the centralized traffic control system for railway. Debug-channel based fuzzing method is required to obtain process status information from the VxWorks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.1
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• pp.68-78
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• 2013

In this paper, we propose an early spectrum sensing(ESS) as an advance preparation for radio-access trial, which enables multi-mode terminals to access the most appropriate radio-access system in a cloud-conceptual base station system where multiple radio access technologies(RATs) coexist. Prior to a random access to one of RATs, a multi-mode terminal conducts a spectrum sensing over entire frequency bands of whole RATs, then select the RAT with the lowest sensing power, that is likely to have the most available spectrum. Thus, an access failure caused by that the selected RAT has no available radio spectrum could be avoidable in advance. In computer simulation, we consider as various RATs as possible. First, circuit and packet systems are taken into consideration. In addition, the packet systems are classified according to the feasibility of carrier aggregation(CA). In case of terminal, three modes are considered with circuit-only, packet-only, and multi-mode. Subsequently, packet traffic is classified into real-time and non-real-time traffic with three different tolerable delay levels. The simulation includes a call process starting with a call generation and ending up with a resource allocation reflecting individual user's QoS requirements and evaluates the proposed scheme in terms of the successful access probability, system access time, system balancing factor and packet loss probability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.1
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• pp.108-126
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• 2013

Recently, it becomes essential for firms or nations to forecast the future and identify emerging technologies in order to improve R&D efficiency and gain a competitive advantage. Particularly, the mobile communications industry is characterized by rapid advance and wide application of its technology and thus identifying emerging technologies is more important in the industry than in others. Nevertheless, few attempts have been made to explore its emerging technologies. Therefore, this research aims to develop a methodology to identify the future and emerging technologies especially for the industry and applied it to list top ten emerging technologies for 2020 in the industry. For this purpose, firstly, we focused the key issues in the future targeting 2020 and identified user needs relating to them. Then, candidates of emerging technologies were defined from a set of technologies to meet the needs, for which technological and economic feasibility is assessed to determine their priorities. Finally, the top ten most important technologies were selected and verified. This research is distinct from the previous studies in that it takes a market-pull approach instead of a technology-push approach. The research results are expected to provide valuable information to support strategy- and policy-makings in the mobile communications industry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1060-1073
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• 2013

In this paper, we present a cluster-based routing scheme for efficiently delivering data to group mobile users by extracting and clustering mobile user group simply from beacon message information in wireless ad-hoc networks. First, we propose an online-clustering mechanism that uses a local neighbor table on each node by recursively transmitting to neighbor nodes, and forms a group table where a set of listed nodes are classified as group members, without incurring much overhead. A node that appears the most frequently from neighbor tables throughout the network is selected as the cluster-head node, serving as a data gateway for the intra-cluster. Second, we design an inter-cluster routing that delivers data from stationary data sources to the selected cluster-head node, and a intra-cluster routing to deliver from the cluster-head node to users. Simulation results based on ns-2 in the ad-hoc networks consisting of 518 stationary nodes and 20 mobile nodes show that our proposed clustering mechanism achieves high clustering accuracy of 96 % on average. Regarding routing performance, our cluster-based routing scheme outperforms a naive one-to-one routing scheme without any clustering by reducing routing cost up to 1/20. Also, our intra-cluster routing utilizing a selected cluster-head node reduces routing cost in half as opposed to a counterpart of the intra-cluster routing through a randomly-selected internal group member.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.12
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• pp.944-953
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• 2013

Recently, a storage media is becoming smaller and storage capacity is also becoming larger than before. However, important data was leaked through a small storage media. To solve these serious problem, many security companies manufacture secure USBs with secure function, such as data encryption, user authentication, not copying data, and management system for secure USB, etc. But various attacks, such as extracting flash memory from USBs, password hacking or memory dump, and bypassing fingerprint authentication, have appeared. Therefore, security techniques related to secure USBs have to concern many threats for them. The basic components for a secure USB are secure authentication and data encryption techniques. Though existing secure USBs applied password based user authentication, it is necessary to develop more secure authentication because many threats have appeared. And encryption chipsets are used for data encryption however we also concern key managements. Therefore, this paper suggests mutual device authentication based on PUF (Physical Unclonable Function) between USBs and the authentication server and key management without storing the secret key. Moreover, secure USB is systematically managed with metadata and authentication information stored in authentication server.