• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.268-275
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• 2020

A lightweight hardware design of self-timed ring based true random number generator (TRNG) suitable for information security applications is described. To reduce hardware complexity of TRNG, an entropy extractor with feedback structure was proposed, which minimizes the number of ring stages. The number of ring stages of the FSTR-TRNG was determined to be a multiple of eleven, taking into account operating clock frequency and entropy extraction circuit, and the ratio of tokens to bubbles was determined to operate in evenly-spaced mode. The hardware operation of FSTR-TRNG was verified by FPGA implementation. A set of statistical randomness tests defined by NIST 800-22 were performed by extracting 20 million bits of binary sequences generated by FSTR-TRNG, and all of the fifteen test items were found to meet the criteria. The FSTR-TRNG occupied 46 slices of Spartan-6 FPGA device, and it was implemented with about 2,500 gate equivalents (GEs) when synthesized in 180 nm CMOS standard cell library.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.125-132
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• 2023

To NP-complete 3-SAT problem, this paper proposes a O(nm) polynomial time algorithm, where n is the number of literals and m is the total frequency of all literals in equation f. Conventionally well-known DPLLs should perform O(2^𝑙) in the worst case by performing backtracking if they fail to find a solution in a brute-force search of a branch-and-bound for the number of literals 𝑙. DPLL forms the core of the SAT Solver by substituting true(T) or false(F) for a literal so that a clause containing the least frequency literal is true(T) and removing a clause containing that literal. Contrary to DPLL, the proposed algorithm selects a literal _max𝑙 with the maximum frequency and sets $_{\max}({\mid}l{\mid},{\mid}{\bar{l}}{\mid})=1$. It then deletes 𝑙∈c_i clause in addition to ${\bar{l}}$ from ${\bar{l}}{\in}c_i$ clause. Its test results on various k-SAT problems not only show that it performs less than existing DPLL algorithm, but prove its simplicity in satisfiability verification.

• ETRI Journal
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• v.22 no.4
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• pp.1-12
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• 2000

Designing a reliable multicast-based network that scales to the size of a multicast group member is difficult because of the diversity of user demands. The loss inferences of internal nodes by end-to-end measurements do not require the use of complete statistics because of the use of maximum likelihood estimation. These schemes are very efficient and the inferred value converges fast to its true value. In the theoretical analysis, internal delay estimation is possible but the analysis is very complex due to the continuity property of the delay. In this paper, we propose the use of a bottleneck location estimator. This can overcome the analytical difficulty of the delay estimation using the power spectrum of the packet interarrival time as the performance metric. Both theoretical analysis and simulation results show that the proposed scheme can be used for bottleneck location inference of internal links in scalable multicasting.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.358-362
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• 2004

Verification and testing are complementary techniques that are used to increase the level of confidence in the correct functioning of communication systems as prescribed by their specifications. This paper presents an experience of model checking for a formal railway signaling protocol specified in LTS (Labeled Transition System). This formal approach checks deadlock, livelock and reachability for the state and action to verify whether properties expressed in modal logic are true on specifications. We also propose a formal method for semi-automated test case generation for a railway signaling protocol described in I/O FSM (Input/Output Finite State Machine). This enables the generation of more complete and consistent test sequence for conformance testing. The above functions are implemented by C++ language and included within RSPVTE (Railway Signaling Protocol Verification and Testing Environment).

• Journal of the Korean Society of Safety
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• v.30 no.2
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• pp.77-82
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• 2015

When accidents that relate to a large numbers of people occur, such as disasters involving group tours by ship or aircraft, or large-scale chemical leakages, it is very important to know the personal identification of victims and to determine their locations and status. It is true that there will be serious damage or injury to people who engaged especially when information does not transfer properly or people get inaccurate one. In this study, therefore, we analysed the disaster response management system for rescued people of the Sewo ferry sinking accident. Based on the analysis we proposed to improve the real-time disaster management system with ICT(Information & Communication Technology).

• Journal of Chest Surgery
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• v.48 no.6
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• pp.404-406
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• 2015

Gebode defect, that can accurately be treated surgical repair, is defined as a true communication between left ventricle and right atrium. A 74-year-old woman with a worsening history of ortophnea and peripheral edema was hospitalised. A communication between right atrium and left ventricle was diagnosed using transeusophageal echocardiography. The defect was repaired and mitral valve was replaced with a biologic valve. It would be beter to tailor surgical strategy for each case with atrioventricular canal defect after preoperative transeusophageal echocardiography and peroperative direct sight.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1997.11a
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• pp.435-449
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• 1997

In this paper, a new metric, universal metric, is Proposed for sequential decoding of convolutional decoding. The complexity of Fano metric for Fano's sequential decoding algorithm is compared with that of the proposed universal metric. Since the Fano metric assumes that it has previous knowledge of channel transition probability, the complexity of Fano metric increases as the assumed channel error probability does not coincide with the true channel error probability. However, the universal metric dose not require the previous knowledge of the channel transition probability since it is estimated on a branch by branch basis. It is shown that the complexity of universal metric is much less than that of the Fano metric for bursty noisy channel.

• Journal of the Korean Institute of Educational Facilities
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• v.5 no.1
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• pp.44-52
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• 1998

Nowadays, social environment is rapidly changed toward globalization and information age, and which demands the new paradigm for active utilization of information system in the field of education and many others. The effort to adapt tele-communication technique to educational facilities and the planning to make virtual university come true are needed immediately. Intelligent Building system should be applied to educational facilities to cope with the changing and progressing building system. As a result of the surveying eleven domestic universities, it was found that library management system, administration automation system and office automation system were already introduced, but campus infrastructure such as network system and tele-communication system between buildings in campus have been constructed now. As the conclusion of this study, impeding factors and improvement direction for active utilization of intelligent building systems in university facilities were presented.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.5
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• pp.601-607
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• 2018

Median filtering is a nonlinear method which is known to be effective in removing impulse noise while preserving local image structure relatively well. However, it could still suffer the smearing phenomena of edges and fine details into neighbors due to undesirable influence from the pixels whose values are far off from the true value of the pixel at hand. This drawback mainly comes from the fact that median filters typically employ a regular shape window for collecting the pixels used in the filtering operation. In this paper, we propose a median filtering method which employs an irregular shape filter window in collecting neighboring pixels around the pixel to be denoised. By employing an irregular shape window, we can achieve good noise suppression while preserving image details. Experimental results have shown that our approach is superior to regular window-based methods.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.635-639
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• 2021

As times goes by, a ton of electric devices have been developing. Nowadays, there are many personal electric goods that are connected each other and have important private information such as identification, account number, passwords, and so on. As many people own at least one electric device, security of the electric devices became significant. To prevent leakage of the information, study of Chaotic TRNG, "Chaotic True Random Number Generator", protecting the information by generating random numbers that are not able to be expected, is essential. In this paper, A chaotic TRNG is introduced is simulated. The proposed Chaotic TRNG is simulated with Virtuoso &, a circuit design program of Cadence that is a software company. For simulating the mentioned Chaotic TRNG, setting values, 0V low and 3V high on Vpulse, 1.2V on V-ref, 3.3V on VDD, and 0V on VSS, are used.