• Journal of Positioning, Navigation, and Timing
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• v.12 no.2
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• pp.201-209
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• 2023

Time comparison techniques are required for generating and keeping Coordinated Universal Time (UTC) and to distribute standard clocks. These techniques play an important role in various fields, including science, finance, military, and communication. Among these techniques, Two-Way Satellite Time and Frequency Transfer (TWSTFT) ensures a relatively high accuracy, with a time comparison accuracy at a nanosecond level. However, TWSTFT systems have some limitations, such as the dependency on extra network links. In this paper, we propose an improved method for TWSTFT system operation and design a message structure for the suggestion. Additionally, we estimate the data rate and redundancy for the new TWSTFT signal with the designed message structure.

• International Journal of Computer Science & Network Security
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• v.24 no.5
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• pp.40-52
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• 2024

Cyber-Physical Systems (CPS) are introduced as complex, interconnected systems that combine physical components with computational elements and networking capabilities. They bridge the gap between the physical world and the digital world, enabling the monitoring and control of physical processes through embedded computing systems and networked communication. These systems introduce several security challenges. These challenges, if not addressed, can lead to vulnerabilities that may result in substantial losses. Therefore, it is crucial to thoroughly examine and address the security concerns associated with CPS to guarantee the safe and reliable operation of these systems. To handle these security concerns, different existing security requirements methods are considered but they were unable to produce required results because they were originally developed for software systems not for CPS and they are obsolete methods for CPS. In this paper, a Security Requirements Engineering Methodology for CPS (CPS-SREM) is proposed. A comparison of state-of-the-art methods (UMLSec, CLASP, SQUARE, SREP) and the proposed method is done and it has demonstrated that the proposed method performs better than existing SRE methods and enabling experts to uncover a broader spectrum of security requirements specific to CPS. Conclusion: The proposed method is also validated using a case study of the healthcare system and the results are promising. The proposed model will provide substantial advantages to both practitioners and researcher, assisting them in identifying the security requirements for CPS in Industry 4.0.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.3
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• pp.553-564
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• 2012

Today's security initiatives tend to integrate the physical and information securities which have been run by completely separate departments. That is, the converged security management becomes the core in the security market trend. However, to the best of our knowledge, we cannot find any solutions how to combine these two security events for the converged security. In this paper, we propose an information security object-driven approach which utilizes the physical security events to enhance and improve the information security. For scalability, we also present a systematic method using the analytic hierarchy process finding the meaningful event combinations among the large number of physical security events. In particular, we show the whole implementation processes in detail where we consider the information security object 'illegal computing system access' combined with two physical security devices - access controller and CCTV+video analyzer system.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.303-310
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• 2016

Due to the ossification of the Internet, it is difficult to accommodate variety services. One of the efficient solution to this problem is network virtualization. It allows multiple parallel virtual networks to run on the shared physical infrastructure. It needs new resource allocation mechanism to share efficient physical resources. In this paper, we present efficient bandwidth allocation algorithm for virtual network request with high service priority. Our proposed algorithm can withdraw allocated bandwidth from low-level priority virtual network and maintain low-level virtual network service. We evaluated the performance of our proposed algorithm using simulation and found the improvement of approximately 8% acceptance rate.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1589-1595
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• 2018

Similarity index measures the topological proximity of node pairs in a complex network. Numerous similarity indices have been defined and investigated, but the dependency of structure on the performance of similarity indices has not been sufficiently investigated. In this study, we investigated the relationship between the performance of similarity indices and structural properties of a network by employing a two-state random network. A node in a two-state network has binary types that are initially given, and a connection probability is determined from the state of the node pair. The performances of similarity indices are affected by the number of links and the ratio of intra-connections to inter-connections. Similarity indices have different characteristics depending on their type. Local indices perform well in small-size networks and do not depend on whether the structure is intra-dominant or inter-dominant. In contrast, global indices perform better in large-size networks, and some such indices do not perform well in an inter-dominant structure. We also found that link prediction performance and the performance of similarity are correlated in both model networks and empirical networks. This relationship implies that link prediction performance can be used as an approximation for the performance of the similarity index when information about node type is unavailable. This relationship may help to find the appropriate index for given networks.

• International Journal of Computer Science & Network Security
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• v.23 no.4
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• pp.69-78
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• 2023

With the global rise of digital data, the uncontrolled quantity of data is susceptible to cyber warfare or cyber attacks. Therefore, it is necessary to improve cyber security systems. This research studies the behavior of malicious acts and uses Higuchi Fractal Dimension (HFD), which is a non-linear mathematical method to examine the intricacy of the behavior of these malicious acts and anomalies within the cyber physical system. The HFD algorithm was tested successfully using synthetic time series network data and validated on real-time network data, producing accurate results. It was found that the highest fractal dimension value was computed from the DoS attack time series data. Furthermore, the difference in the HFD values between the DoS attack data and the normal traffic data was the highest. The malicious network data and the non-malicious network data were successfully classified using the Receiver Operating Characteristics (ROC) method in conjunction with a scaling stationary index that helps to boost the ROC technique in classifying normal and malicious traffic. Hence, the suggested methodology may be utilized to rapidly detect the existence of abnormalities in traffic with the aim of further using other methods of cyber-attack detection.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.5 s.335
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• pp.23-28
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• 2005

Recently, new concept, NP(Network Processor) was emerged into communication systems to cope with the various service requirements from Internet users. NP is an unique promising technique to capable of implementing of the packet processing in wire-speed and providing the flexibility for supporting the newly network services, having satisfied with implementation using hardware and software respectively in past, This paper deals with the implementation techniques and evaluation results of the line card capable to do packet forwarding function with packet processing power of wire-speed and applicable to various physical interfaces. There are several interfaces of POS, Gigabit ethernet and EPON in E-OLT(EPON Optical Line Terminal) system of PATH(Photonic Access To Home) network. Therefore, the E-OLT's packet forwarding engine have to support various subscriber's interface in wire speed. Our system is implemented the subscriber's card in daughter board and the setup procedure is done by system firmware based on the module's identifier acquired from installed physical board.

• Convergence Security Journal
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• v.13 no.3
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• pp.85-90
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• 2013

To provide high-quality services, national public institutions and companies have provided information and materials over the internet network. However, a risk of malware infection between transmission and reception of data leads to exposure to various security threats. For this reason, national institutions have proceeded with projects for network separation since 2008, and data linkage has been made using network connection storage through network separation technologies, along with physical network separation. However, the network connection storage has caused waste of resources and problems with data management due to the presence of the same data in internal network storage and external network storage. In this regard, this study proposes a method to connect internal and external network data using NAS storage as a way to overcome the limitations of physical network separation, and attempts to verify the priority of items for the optimization of network separation by means of AHP techniques.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.31-37
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• 2010

This study was developed the home network system for the home stay care by bio-sensor system to translate the physical signal algorithm. The composition algorithm has five functions for a input function, frequency variable, displacement point input function, axial Variable, axial Sway Displacement to search a max and min point with adjustment of 0.01 unit in the reference level. There were checked physical condition of body balance to compounded a measurement such as a heart rate, temperature, weight. The algorithm of home network system can be used to support health care management system through health assistants in health care center and central health care system. It was expected to monitor a physical parameter for health management system.

• Journal of Korean Society of Rural Planning
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• v.25 no.2
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• pp.89-98
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• 2019

The purpose of this study is to develop the evaluation factors for formation of the future - oriented rural residential environment and to derive the importance of this evaluation factors. The main research methods are network analysis using Net-miner, AHP analysis and importance analysis for experts. The main research results are as follows. First, 6 factors for evaluation rural residential environment(environmental-sustainability, communality, self-reliance, aesthetic, enjoyment, settlement), 3 sub-factors of each factors, and key physical facilities(10 for rural center and 28 for rural villages) were derived by literature analysis and network analysis on it. Second, key priority factors that should be considered in physical formation of rural residential environment was deducted by AHP analysis. Improving accessibility of living services in the settlement factor, improvement of garbage collection and wastewater treatment system around the residential area, and ensuring topographic continuity in the environmental-sustainability factor was derived as a priority factors. Third, as a result of evaluation of the importance of physical facilities in the rural residential environment, there was a high demand for cultural welfare facilities in common. However, when compared with the villages where the harmony between the natural environment and the living environment is emphasized, convenience of living and accessibility of transportation were important in the rural center. These results suggest that solving the qualitative conditions as residential environment will help to attract new population. This study will contribute to enhance the qualitative level of the rural residential environment by suggesting strategic priority items when carrying out projects related to the rural residential environment creation in the future.