• Title/Summary/Keyword: H.235

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Implementation of Secure VoIP System based on H.235 (H.235 기반 VoIP 보안 시스템 구현)

  • 임범진;홍기훈;정수환
    • Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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    • 2001.11a
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    • pp.241-245
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    • 2001

  • 인터넷 서비스와 함께 발달한 멀티미디어 서비스 중 각광받고 있는 VoIP 서비스는 유선 전화보다 저렴한 가격을 바탕으로 하여 호황을 누리고 있다. 그러나 인터넷을 전송망으로 이용하는 VoIP는 개인의 암호화되지 않은 음성데이터의 도청이 쉽게 이루어질 수 있을 뿐만 아니라 사용자 및 서비스 업자에 대한 인증 방법 부재로 인한 불법 이용이 예상되는 등 보안적 문제점을 가지고 있다. 그에 따른 VoIP 서비스의 보안 요구사항은 계속 증가하고 있으며 이에 대한 연구 노력이 시급하다. 본 논문에서는 ITU에서 제안한 H.323 VoIP의 보안 프로토콜인 H.235에 대하여 연구하고 이를 구현한 VoIP 보안 시스템을 구축하여 VoIP 보안 프로토콜의 요구 사항 및 방향을 제시하였다.

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Sensitivity Analysis of the Criticality Evaluation Concerning Pyroprocess

  • Gao, Fanxing;Ko, Won-Il;Park, Chang-Je;Lee, Ho-Hee
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2010.05a
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    • pp.271-272
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    • 2010

  • Sensitivity analysis by TSUNAMI clarifies the complex effects of key nuclides on the criticality probability quantitatively. As discussed above, the $K_{eff}$ of $UO_2$ fuel reaches the maximum value with 42w% concentration of intrusion water. The concentration of hydrogen affects the complexity of reaching criticality by its competition between the concentrations of $^{235}U$. Approximately if the weight percent of $H_2O$ in the mixture is less than 42%, the moderation effect of hydrogen surpasses its dilution effect on $^{235}U$. However, the importance of $^{235}U$ increases dramatically when the weight percent of water is bigger than 42%. In the sensitivity evaluation of $UO_2$ fuel employing TSUMAMI, there is a similar crosspoint of the sensitivity of $^{235}U$ and the sensitivity of $^1H$ where the criticality reaches summit. And the optimal water weight percent is determined to be 50%.

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An Application of Design of Experiments for Optimization of MOF-235 Synthesis for Acetylene Adsorption Process (아세틸렌 흡착공정용 MOF-235 합성 최적화를 위한 실험 계획법 적용)

  • Cho, Hyungmin;Yoo, Kye Sang
    • Applied Chemistry for Engineering
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    • v.31 no.4
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    • pp.377-382
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    • 2020

  • A sequential design of experiments was employed to optimize MOF-235 synthesis for acetylene adsorption process. Two experimental designs were applied: a two-level factorial design for screening and a central composite design, one of response surface methodologies (RSM). In this study, 23 factorial design of experiment was used to evaluate the effect of parameters of synthesis temperature and time, and also mixing speed on crystallinity of MOF-235. Experiments were conducted 16 times follwing MINITAB 19 design software for MOF-235 synthesis. Half-normal, pareto, residual, main and interaction effects were drawn based on the XRD results. The analysis of variance (ANOVA) of test results depicts that the synthesis temperature and time have significant effects on the crystallinity of MOF-235 (response variable). After screening, a central composite design was performed to optimize the acetylene adsorption capacity of MOF-235 based on synthesis conditions. From nine runs designed by MINITAB 19, the result was calculated using the second order model equation. It was estimated that the maximum adsorption capacity (18.7 mmol/g) was observed for MOF-235 synthesized at optimum conditions of 86.3 ℃ and 28.7 h.

  • https://doi.org/10.14478/ace.2020.1039 인용 PDF KSCI

Characterization of Antimicrobial Substance Produced by Lactobacillus sp. HN 235 Isolated from Pig Intestine (돼지 장관으로부터 분리한 Lactobacillus sp. HN 235 균주가 생산하는 항균물질의 특성)

  • Shin, Myeong-Su;Han, Sun-Kyung;Choi, Ji-Hyun;Ji, Ae-Ran;Kim, Kyeong-Su;Lee, Wan-Kyu
    • Microbiology and Biotechnology Letters
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    • v.37 no.2
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    • pp.125-132
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    • 2009

  • In order to develop probiotics which may be a viable alternative of antibiotic use in pig industry, five bacterial strains (Lactobacillus sp. HN 52, 92, 98, 235 and AP 116) possessing antimicrobial properties were selected from 500 strains isolates of pig intestines. The bacteriocin produced by Lactobacillus sp. HN 235 displayed a relative broad spectrum of inhibitory activity against all Enterococcus strains, Pseudomonas aeruginosa, Listeria monocytogenes and Clostridium perfringens using the spot-on-lawn method. The production of antimicrobial substance started in the middle of the exponential growth phase, reached maximum levels (6,400 AU/mL) in the stationary phase, and then declined. Bacteriocin activity remained unchanged after 30 min of heat treatment at $95^{\circ}C$ and stable from pH 2.0 to 10 for 1 h, or exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. The molecular weight of the bacteriocin was about 5 kDa according to a tricine SDS-PAGE analysis.

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