• Journal of Communications and Networks
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• v.9 no.4
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• pp.499-510
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• 2007

Shortest path tree(SPT) construction is essential in high performance routing in an interior network using link state protocols. When some links have new state values, SPTs may be rebuilt, but the total rebuilding of the SPT in a static way for a large computer network is not only computationally expensive, unnecessary modifications can cause routing table instability. This paper presents a new update algorithm, dynamic shortest path tree(DSPT) that is computationally economical and that maintains the unmodified nodes mostly from an old SPT to a new SPT. The proposed algorithm reduces redundancy using a dynamic update approach where an edge becomes the significant edge when it is extracted from a built edge list Q. The average number of significant edges are identified through probability analysis based on an arbitrary tree structure. An update derived from significant edges is more efficient because the DSPT algorithm neglect most other redundant edges that do not participate in the construction of a new SPT. Our complexity analysis and experimental results show that DSPT is faster than other known methods. It can also be extended to solve the SPT updating problem in a graph with negative weight edges.

• Journal of Information Technology Applications and Management
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• v.11 no.2
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• pp.179-190
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• 2004

This paper describes the design of hacking prevention systems using a smart card. It consists of two parts, i.e., PC authentication and Keyboard-buffer hacking prevention. PC authentication function is a procedure to handle the access control to the target PC. The card's serial number is used for PIN(Personal Identification Number) and is converted into hash-code by SHA-1 hash-function to verify the valid users. The Keyboard-buffer hacking prevention function converts the scan codes into the encoded forms using RSA algorithm on the Java Card, and puts them into the keyboard-buffer to protect from illegal hacking. The encoded information in the buffer is again decoded by the RSA algorithm and displayed on the screen. in this paper, we use RSA_PKCS#1 algorithm for encoding and decoding. The reason using RSA technique instead of DES or Triple-DES is for the expansion to multi-functions in the future on PKI. Moreover, in the ubiquitous computing environment, this smart card security system can be used to protect the private information from the illegal attack in any computing device anywhere. Therefore, our security system can protect PC user's information more efficiently and guarantee a legal PC access authority against any illegal attack in a very convenient way.

• Steel and Composite Structures
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• v.15 no.5
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• pp.519-538
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• 2013

The design optimization of a cold-formed steel portal frame building is considered in this paper. The proposed genetic algorithm (GA) optimizer considers both topology (i.e., frame spacing and pitch) and cross-sectional sizes of the main structural members as the decision variables. Previous GAs in the literature were characterized by poor convergence, including slow progress, that usually results in excessive computation times and/or frequent failure to achieve an optimal or near-optimal solution. This is the main issue addressed in this paper. In an effort to improve the performance of the conventional GA, a niching strategy is presented that is shown to be an effective means of enhancing the dissimilarity of the solutions in each generation of the GA. Thus, population diversity is maintained and premature convergence is reduced significantly. Through benchmark examples, it is shown that the efficient GA proposed generates optimal solutions more consistently. A parametric study was carried out, and the results included. They show significant variation in the optimal topology in terms of pitch and frame spacing for a range of typical column heights. They also show that the optimized design achieved large savings based on the cost of the main structural elements; the inclusion of knee braces at the eaves yield further savings in cost, that are significant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3041-3063
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• 2018

Community search aims at finding a meaningful community that contains the query node and also maximizes (minimizes) a goodness metric. This problem has recently drawn intense research interest. However, most metric-based algorithms tend to include irrelevant subgraphs in the identified community. Apart from the user-defined metric algorithm, how can we search the natural community that the query node belongs to? In this paper, we propose a novel community search algorithm based on the concept of the k-hop and local distance dynamics model, which can naturally capture a community that contains the query node. The basic idea is to envision the nodes that k-hop away from the query node as an adaptive local dynamical system, where each node only interacts with its local topological structure. Relying on a proposed local distance dynamics model, the distances among nodes change over time, where the nodes sharing the same community with the query node tend to gradually move together, while other nodes stay far away from each other. Such interplay eventually leads to a steady distribution of distances, and a meaningful community is naturally found. Extensive experiments show that our community search algorithm has good performance relative to several state-of-the-art algorithms.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.199-204
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• 2020

With the development of IT. convergence systems are applied and operated in many different fields. A representative field among them is medical service, which develops in diverse types in combination with nano-technology and bio technology. However, there is a lack of technical innovation in terms of medical data operation and management. For example, data and documents are saved and integrated separately depending on their forms when electronic health records or data like SAM files are transmitted or kept. In other cases, such records and data are still kept after being recorded in paper. This study tries to design and implement the EMR system that makes it possible to capsulize forms of data and documents and to digitalize documents in work process as they are in terms of operation and storage. The system is expected to support efficient operation of electronic documents in the aspects of work and management.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.769-776
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• 2016

TELNET is vulnerable to network attack because it was designed without considering security. SSL/TLS and SSH are used to solve this problem. However it needs additional secure protocol and has no backward compatibility with existing TELNET in this way. In this paper, we have suggested STELNET(Secured Telnet) which supports security functionalities internally so that has a backward compatibility. STELNET supports a backward compatibility with existing TELNET through option negotiation. On STELNET, A client authenticates server by a certificate or digital signature generated by using ECDSA. After server is authenticated, two hosts generate a session key by ECDH algorithm. And then by using the key, they encrypt data with AES and generate HMAC by using SHA-256. After then they transmit encrypted data and generated HMAC. In conclusion, STELNET which has a backward compatibility with existing TELNET defends MITM(Man-In-The-Middle) attack and supports security functionalities ensuring confidentiality and integrity of transmitted data.

• Journal of Internet Computing and Services
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• v.11 no.4
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• pp.23-32
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• 2010

In this paper, we first propose the security enhancing of authentication protocol for Hash based RFID tag, and then a digital Codec for RFID tag is designed based on the proposed authentication protocol. The protocol is based on a three-way challenge response authentication protocol between the tags and a back-end server. In order to realize a secure cryptographic authentication mechanism, we modify three types of the protocol packets which defined in the ISO/IEC 18000-3 standard. Thus active attacks such as the Man-in-the-middle and Replay attacks can be easily protected. In order to verify effectiveness of the proposed protocol, a digital Codec for RFID tag is designed using Verilog HDL, and also synthesized using Synopsys Design Compiler with Hynix $0.25\;{\mu}m$ standard-cell library. Through security analysis and comparison result, we will show that the proposed scheme has better performance in user data confidentiality, tag anonymity, Man-in-the-middle attack prevention, replay attack, forgery resistance and location tracking.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.485-492
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• 2008

Computers used fer light-weight computing environments are considerably limited in resources and performance running in ubiquitous environment. Because of the limited resources, it is difficult to apply existing security technologies to the light-weight computers. In this paper, light-weight security software is implemented using RC-5 encryption and SHA-1 authentication algorithm which is appropriate for light-weight computing environments. The design of components based on security software of a light-weight computer application and the test-bed for security software are presented. The simulation verifies the correctness of the security software. The architecture of the light-weight and reconfigurable security software for light-weight computer applications is proposed. The proposed security software is small size and provides reconfigurable security library based on the light-weight component and the software manager that configures software platform is loaded with the library at the time it is needed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1071-1077
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• 2022

A security SoC that can be used to implement elliptic curve cryptography (ECC) based public-key infrastructures was designed. The security SoC has an architecture in which a hardware accelerator for the elliptic curve digital signature algorithm (ECDSA) is interfaced with the Cortex-A53 CPU using the AXI4-Lite bus. The ECDSA hardware accelerator, which consists of a high-performance ECC processor, a SHA3 hash core, a true random number generator (TRNG), a modular multiplier, BRAM, and control FSM, was designed to perform the high-performance computation of ECDSA signature generation and signature verification with minimal CPU control. The security SoC was implemented in the Zynq UltraScale+ MPSoC device to perform hardware-software co-verification, and it was evaluated that the ECDSA signature generation or signature verification can be achieved about 1,000 times per second at a clock frequency of 150 MHz. The ECDSA hardware accelerator was implemented using hardware resources of 74,630 LUTs, 23,356 flip-flops, 32kb BRAM, and 36 DSP blocks.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.2
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• pp.1-11
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• 2005

The network structures of a hyperlinked environment can be a rich source of information about the contents of the environment and it provides effective means for understanding it. Recently, there have been a number of algorithms proposed analyzing hypertext link structure so as to determine the best authorities for a given topic or query. In this paper, we review the algorithm of mutual reinforcement relationship for finding hubs and authorities from World Wide Web, and suggest SHA, a new approach for link-structure analysis, which uses the relationships among a set of relative authoritative pages, a set of hub pages, and a set of super hub pages.