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임베디드 환경에서의 H.235 기반 VoIP 보안 단말 구현 및 안전성 분석에 관한 연구
김덕우,홍기훈,이상학,정수환 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.7C
본 논문에서는 ITU-T에서 제안한 VoIP 표준인 H.323 시스템의 보안 프로토콜인 H.235에 대하여 연구하고 이를 임베디드 환경의 IP Phone에 구현하여 VoIP 보안 프로토콜의 구현 요구사항 및 구현 결과에 따른 분석을 실시하였다. 특히 annex D에서 제안하고 있는 VoIP 단말에서의 보안 기능을 분석하여 구현하였는데, annex D에서는 HMAC-SHAI-96을 이용하여 인중과 무결성을 제공하고 Diffie-Hellman을 이용해서 음성 데이터 암호화에 사용되는 세션 키를 암호화해서 전달하며 음성 데이터의 암호화를 위한 RC2, DES, 3DES 등을 지원하고 있다. 또한 annex D의 안전성 및 상호 연동 문제점을 분석하여 취약점을 발견하고 보안을 강화하는 개선 방안을 제시하였다. In this paper, H.235 based security mechanism for H.323 multimedia applications was implemented in embedded environment. H.235 covers authentication using HMAC-SHAI -96, authenticated Diffie-Hellman key exchange, security capability exchange, session key management for voice encryption, and encryption functions such as DES, 3DES, RC2. H.235-based mechanisms were also analyzed in terms of its security and possible attacks.
복강경 대장절제술 전 대장내시경하 인디아잉크 문신술의안전성과 효용성
김덕우,손대경,최효성,장희진,한경수,임석병,정승용,박재갑 대한대장항문학회 2006 Annals of Coloproctolgy Vol.22 No.2
Purpose: Accurate tumor localization prior to a laparoscopic surgical resection is the critical. India ink tattoos properly placed in the colorectum are long lasting and have been reported to probably remain constantly in previous studies. The present study was done to review the safety and reliability of colonoscopic tattooing prior to a laparoscopic resection of a colorectal neoplasm. Methods: Between May 2003 and August 2004, 20 patients underwent colonoscopic tattooing of a colorectal neoplasm prior to laparoscopic surgery. The clinical data were retrospectively reviewed. Results: Among the 20 patients, 14 (70%) had tumors located in the sigmoid colon, 4 (20%) had tumors in the rectosigmoid junction, and 1 had a tumor (5%) in the upper rectum and descending colon. In six patients (30%) who had received an endoscopic mucosal resection (EMR), an additional surgical resection was required to remove the tumor completely, and those 6 patients needed another preoperative colonoscopy for India ink tattooing. The median time between tattooing and resection was 2 days (range: 1 to 18 days). Tattoos were visualized intraoperatively and localized the tumor accurately in 15 patients (75%). Seven patients underwent intraoperative colonoscopy; five didn't have tattoos that could be visualized intraoperatively, and two patients with visible tattoos needed intraoperative colonoscopy to confirm the site of tumor. Only one patient (5%) had mild fever with abdominal discomfort, which were relieved by hydration and administration of intravenous antibiotics for one day. Conclusions: A colorectal neoplasm can be localized with an acceptable reliability by using preoperative colonoscopic tattooing. India ink tattooing at the time of the EMR may reduce unnecessary colonoscopies if we doubt a complete resection has been achieved by using an EMR. The complications following colonoscopic tattooing were minimal.