안전한 멀티캐스트 서비스 제공을 위한 효율적인 그룹 관리 기법

은상아(Sang-A Eun),조태남(Tae-Nam Cho),채기준(Kijoon Chae),이상호(Sang-Ho Lee),박원주(Won-Joo Park),나재훈(Jae-Hoon Na) 한국통신학회 2002 한국통신학회 학술대회 및 강연회 Vol.2002 No.4

안전한 멀티캐스트 서비스 제공을 위한 효율적인 그룹 관리 메커니즘 및 구조

은상아,조태남,채기준,이상호,박원주,나재훈,Eun, Sang-A,Jo, Tae-Nam,Chae, Gi-Jun,Lee, Sang-Ho,Park, Won-Ju,Na, Jae-Hun 한국정보처리학회 2002 정보처리학회논문지 C : 정보통신,정보보안 Vol.9 No.3

멀티캐스트 서비스들이 점차 다양해지고, 서비스 사용자의 폭도 넓어지고 있다. 이에 비례하여 공격자들의 주목을 받게되고 정보의 누출 가능성도 높아진다. 따라서 멀티캐스트 서비스 활용과 동시에 그에 대한 보안 연구도 함께 이루어져야 한다. 본 논문에서는 멤버의 동적인 가입 탈퇴가 발생하는 그룹에서 효율적인 그룹 관리를 적용하여 안전한 멀티캐스트 서비스를 제공할 수 있는 구조를 제안한다. 제안한 구조는 한 명의 송신자와 다수의 수신자로 구성된 멀티캐스트 통신 상황에서, 보안 측면을 고려하여 많은 이용자들에게 안전한 멀티캐스트 서비스를 제공할 수 있다. 시뮬레이션을 통하여 기존의 구조와 성능을 비교·분석한 결과, 제안하는 구조는 멤버 관리가 효율적이고, 전송 지연을 줄이면서 보다 안전하게 데이터를 전송할 수 있다는 것을 알 수 있었다. Multicast services are gradually diversified and used widely. Proportionately, they become the center of attackers' attention and there are growing possibilities of an intelligence leak. Therefore, research related to secure multicast should be required to provide multicast service efficiently. This paper presents the architecture for secure multicast which provides efficient group management mechanism in group consists using member's dynamic join and leave. This architecture can provide secure multicast services to many users with regard to security aspects in one-to-many communication. The simulation results show that the proposed architecture achieves an efficient group management and a secure data transmission with low latency compared with the other existing secure multicast architecture.

전산화단층사진을 이용한 치성각화낭과 법랑모세포종의 감별진단

은상아,김기덕,박창서,Eun Sang-A,Kim Kee-Deog,Park Chang-Seo 대한영상치의학회 2002 Imaging Science in Dentistry Vol.32 No.2

Purpose: The objective of this study is to find the differentiating characteristics of ameloblastomas and odontogenic keratocysts of the jaw by analyzing computed tomography (CT) images of the lesions, clarify radiological characteristics associated with jaw lesions, and to make a diagnsis based on these findings. Materials and Methods : Test subjects were chosen among the patients who were diagnosed as having an odontogenic keratocyst or ameloblastoma at the Yonsei University Dental Hospital from January 1996 to December 2000 and had CT scans taken preoperatively. The subject pool was comprised of 51 cases of odontogenic keratocyst and 37 cases of ameloblastoma. The following measures were used for image analysis of the lesion: the anatomic location, CT pattern, mesiodistal width, buccolingual width, the ratios between mesiodistal width and buccolingual width, height, CT number, homogeneity of radiodensity, the appearance of a sclerotic rim, continuity of adjacent cortical bone, and displacement and resorption of adjacent teeth. Results: Comparing the CT patten, mesiodistal width, buccolingual width, height, CT number, homogeneity, appearance of sclerotic rim, continuity of adjacent cortical bone, there were statistically significant differences between ameloblastoma and odontogenic keratocyst test subjects (p<0.05). Comparing the ratios between mesiodistal width and buccolingual width, displacement and resorption of adjacent teeth, there were no statistically significant differences (p>0.05). Conclusion: We compared odontogenic keratocysts and ameloblastomas in CT scans. They occurred most frequently in the posterior to the ramus of the mandible. The findings of patterns of the CT images showed that size and border of lesions were more aggressive in ameloblastomas than in odontogenic keratocysts. The internal contents represented an increased attenuation area (IAA) in odontopenic keratocyst. Odontogenic keratocysts were shown to have higher CT numbers than ameloblastomas.

다중 코어 기반 트리를 이용한 2계층 그룹키 관리 구조 및 프로토콜

조태남(Taenam Cho),김상희(Sanghee Kim),은상아(Sang-A Eun),이상호(Sang-Ho Lee),채기준(Kijoon Chae),박원주(Wonjoo Park),나재훈(Jaehoon Nah) 한국정보과학회 2002 정보과학회논문지 : 정보통신 Vol.29 No.5

Assuring the security of group communications such as tele-conference and software distribution requires a common group key be shared among the legal members in a secure manner. Especially for large groups with frequent membership change, efficient rekey mechanism is essential for scalability. One of the most popular ways to provide scalable rekey is to partition the group into several subgroups. In this paper, we propose a two-layered key management scheme which combines DEP and CBT, a protocol in which subgroup manager cannot access the multicast data and another that has a multi-core, respectively. We also select sub-group key management protocols suitable for our structure and design new rekey protocols to exclude the subgroup managers from the multicast data. Compared to previous protocols based on CBT, our scheme provides forward secrecy, backward secrecy and scalability. This would reduce the number of encryption and decryption for a rekey message and would improve the efficiency number of rekey messages and the amount of information related to group members that group managers must maintain compared to DEP. 원격회의나 소프트웨어 배포 등 다양한 멀티캐스팅 응용 서비스의 보안을 위해서는 정당한 멤버들만이 비밀리에 그룹키를 공유하여야 한다. 특히 그룹의 규모가 크고 멤버의 변동이 빈번한 경우에는 확장성을 위하여 효율적으로 그룹키를 갱신할 수 있어야 하는데, 확장성 있는 키 갱신을 위한 한가지 방편으로서 서브 그룹 구조를 사용한다. 본 논문에서는 서브 그룹 관리자를 그룹 멤버와 분리시킨 DEP 구조와 다중 코어를 갖는 멀티캐스트 프로토콜인 CBT를 접목한 2계층 관리 방식을 제안하고, 제안한 구조에 적합한 서브 그룹키 관리 프로토콜을 선정하였으며, 서브 그룹 관리자를 그룹 통신으로부터 배제하기 위한 키 갱신 프로토콜을 설계하였다. 이것은 기존의 CBT에 기반한 키관리 프로토콜에 비하여 forward secrecy와 backward secrecy 및 확장성을 제공한다. 또한, 2계층 관리 구조를 갖도록 함으로써 DEP에 비하여 키 갱신 메시지의 암 · 복호화 수를 줄였으며, 키 관리의 효율성을 높이고 그룹 관리자가 유지해야 하는 그룹 멤버에 대한 정보량을 감소시켰다.

다중 코어를 가지는 CBT에서의 그룹키 관리

조태남(Tae-Nam Cho),김상희(Sang-Hee Kim),은상아(Sang-A Eun),이상호(Sang-Ho Lee),채기준(Kijoon Chae),박원주(Won-Ju Park),나재훈(Jae-Hoon Na) 한국정보과학회 2002 한국정보과학회 학술발표논문집 Vol.29 No.1A

원격화상회의나 소프트웨어 배포 등 멀티캐스팅의 보안을 위해서 사용하는 그룹키는 그룹의 규모가 클 경우에도 멤버쉽 변화에 대하여 효율적으로 갱신이 이루어져야 한다. 본 논문에서는 DEP 구조를 멀티캐스트 프로토콜인 CBT에 적용한 2계층 관리 구조를 제안함으로써 키갱신 메시지 전송의 암 · 복호화 횟수를 제한하였으며, 서브 그룹 관리자를 그룹 통신으로부터 배제할 수 있는 효율적인 키관리 프로토콜을 제시하였다.

랫드에서 Perfluorooctanoic Acid의 독성에 관한 연구

김용훈,조은상,김아영,김성환,박민식,조성환,류시윤,정주영,손화영,Kim, Yong-Hoon,Cho, Eun-Sang,Kim, A-Young,Kim, Sung-Hwan,Park, Min-Sik,Cho, Sung-Whan,Ryu, Si-Yun,Jung, Joo-Young,Son, Hwa-Young 대한수의학회 2008 大韓獸醫學會誌 Vol.48 No.3

Perfluorooctanoic acid (PFOA), a member of the perfluoroalkyl acids that have wide commercial applications, is persistent organic pollutants widely spread throughout the environment and human population. But little is known about the adverse biological effects of the PFOA. In the present study, the toxicological effects of PFOA were investigated in rats. Sprague-Dawley rats (N = 10 in each group) were orally administered with PFOA in drinking water for 4 weeks (0, 100, 200, or 400 ppm in male, and 0, 200, 400, or 800 ppm in female). Three female rats given 800 ppm died during the study. PFOA treatment decreased the body weight gain and increased the liver weights in both genders. Serum biochemical investigations revealed significant increases in the aspartate aminotransferase, alanine transaminase, alkaline phosphatase, blood urea nitrogen, total cholesterol, and total bilirubin in male but in female. Serum estradiol (E2) levels were increased in all treated rats. Histopathologically, hepatocellular hypertrophy around central vein was noted in the liver of treated rats. No significant histopathological changes were noted in other organs. In conclusion, PFOA induced toxicological changes in the liver and increased serum E2 level which was not related to histopathological changes of endocrine and reproductive system.

우리나라 산성강하물의 장기변동 특성 연구

장성기(Seong-Ki Jang),성민영(Min-Young Sung),신아윤(A-Youn Shin),최진수(Jin-Su Choi),손정석(Jung-Suk Son),안준영(Joon-Young Ahn),김종춘(Jong-Chun Kim),신은상(Eun-Sang Shin) 한국환경관리학회 2011 環境管理學會誌 Vol.17 No.3

This study is aimed at finding the characteristics of long-term trends in wet and dry deposition in Korea. NIER(National Institute of Environmental Research) has monitored major ion components of wet and dry deposition since 1999. The institute also has carried out researches in order to estimate the critical loads for ecosystem based on the collected data from 1999 to 2009. Sampling was conducted at 38 acid deposition monitoring sites and major ion components such as SO₄²?, Cl?, NO₃?, NH₄?, Na?, K?, Ca²? and Mg²? were analyzed by using ion chromatograph. The results helped find out changes in acid deposition for ten years(1999∼2009) in Korea. The data from 10 monitoring sites showed that average annual pH for the monitoring period was 5.1 with the maximum pH level of 6.2 in Imsil(2007) and its minimum level of 4.2 in Deajeon(2008). Of 10 monitoring sites, pH levels of Gwangju, Daejeon, Seoul, Taean and Gangwha have decreased and there was not much change of pH in rural areas. The total deposition of sulfur showed a decreasing trend of 1.44, 1.89, 2.02, 1.26, 1.33, 1.28 g/㎡ㆍyear from 2005 to 2010 while the total deposition of nitrogen was 1.29, 1.72, 2.58, 2.14, 2.49, 2.31 g/㎡ㆍyear during the same period showing an increasing trend. Sulfur concentration was lower in 2008 and 2009 compared to that of 2006 and 2007 and, in particular, the concentration monitored at Seoul was slightly higher than others. As for nitrogen, its concentration was observed to be high in some part of the Seoul Metropolitan Area(SMA) and low in 2009.