체계적인 보안 정책 관리를 위한 계층적 보안 모델 설계

황윤철,엄남경,장재웅,이상호 충북대학교 컴퓨터정보통신 연구소 2001 컴퓨터정보통신연구 Vol.9 No.1

인터넷 서비스의 다양화와 인터넷을 구성하는 네트워크의 대형화로 인해 다양한 특성을 갖는 구성요소와 환경 등의 요인으로 시스템간의 거래에 대한 보안정책 설정 및 제어가 어려운 문제로 등장하고 있다. 보안 정책 기술이란 인터넷상에서 정보보호 기능을 구현할 때 적용하는 정책들에 대한 검색, 접근제어, 분배 및 처리하는 기술을 의미한다. 이 논문에서는 이러한 현실적인 문제를 해결하기 위해 대형화되어 가는 인터넷 전체에 걸쳐 효율적으로 적용할 수 있는 계층적 구조의 보안 정책 모델을 설계한다. Security policy association and control about transaction between systems must be hard problem to solve because of the environment and composite factors with variable properties by diversity of internet service and enlarging a scale of organizing internet. Security policy technique means retrieval, access, control, distribute and process technique about adoptable policies when implementation is information security function on internet. In this paper, to solve this actual problems, Design of a hierarchical structure security policy model applicable to internet.

强風의 發生成因別 時間的 變化에 관한 硏究

황진득,하영철,곽윤근 金烏工科大學校 1994 論文集 Vol.15 No.-

The wind resistant design of building generally used up to data has been based on the value of an extreme speed. The extreme speed is normally estimated from wind data observed for the return periods of last 50 years or 100 years on the basis of the importance of building to be constructed. However, it is essential to consider the time variance of wind action because strong winds originated by Typhoon or others are occationally coming for attack. This study is to examine the origin of occurence and the action time of strong wind, and to understand the time variance characteristics. Strong winds are divided into 3 parts such as the regional condition of Korea, namely Typhoon, Frontal system storm, and Monsoon. The areas reflecting the origin of 3 kinds of the strong winds are also devided are selected as such as Seoul-Kyongki, Jungbu, and South-seashore. The representative cities are selected as Seoul fro, Uljin and Kunsan for, and Busan and Yeosu for. Observed wind data of past 20 years will be employed to estimate duration and propability of wind velocity. The observed wind data are recorded with duration of 96 hours at the center that annual extreme wind speed takes place, and with the mean value of wind velocity during 10 minutes at 1 hour interval. Based on these investigations, the duration and probability of wind velocity should be estimated. Generalized probability distribution function of wind velocity will be proposed. Duration of strong winds presented as a function of its maximum wind velocity. From these results, multipling generalized distribution function by generalized number of (wind velocity) samples, approximate equation of wind-duration will be derived. Approximate equation of wind-duration proposed in this study should be useful for analysing fatigue damage of structures and time dependent analysis of structure under strong wind in Korea.

2-Fluorenyl chalcone 유도체의 합성과 가수분해반응에 관한 연구

이기창,황성규,윤철훈,오세영 명지대학교 자연과학연구소 1995 자연과학논문집 Vol.12 No.-

Fluorenyl chalcone 유도체를 합성하였고 25 ±1℃의 20% dioxane-H?O 혼합용매 중에서 자외선 분광광도법을 이용하여 pH 1.0~13.0까지의 넓은 pH범위에서 가수분해 반응속도를 측정하였다. 또한 Fluoreny chalcone 유도체의 pH변화에 따른 반응속도로 측정하고, 일반염기효과, 치환기효과 및 가수 분해 생성물 확인 등으로부터 Fluorenyl chalcone 유도체에 대한 가수분해 반응속도상수를 구하였다. 이들 유도체들은 pH와 무관한 부분과 수산화 이온농도에 비례하며, pH와 무관한 부분에서는 중성의 물분자가 첨가된다. 반응속도 상수 측정으로부터 Fluorency chalcon 유도체의 가수분해 반응은 비가역 1차 반응임을 확인하였고, 치환기효과로부터 전자유인성기에 의해 반응이 촉진되는 것을 알 수 있었다. 또한, 가수분해 최종 생성물은 확인 결과 2 ~acetyl fluorene과 벤즈알데히드였다. 이러한 실험결과를 토대로 하여 Fluorenyl chalcone 유도체에 대한 가수분해 반응 메카니즘을 제안하였다. Fluorenyl chalcone derivatives were synthesis, it was measured that hydrolysis made use of ultraviolet spectrophotometry at a wide pH 1.0 ~ 13.0 range in 20% dioxane-H?O solution, 25±1℃. On the basis of general base catalysis, substitutent effect and confirmation of hydrolysis product, it was measured the reaction rate of fluorenyl chalcone derivatives for the pH change. It maybe concluded that a part was unrelated to pH and another part was in proportion to concentration of hydroxide ion: Above pH 10.0, It was in propotion to concentration of hydroxide ion, a part having no concern with pH was added to the neutral H?O molecule. From the result of measurement the reaction rate, hydrolysis of fluorenyl chalcone derivatives confirmed to the irreversible first order through measurement the substituent effect, It was found that reaction rate was accelerated first order through measurement the substituent effect, It was found that reaction rate was accelerated by electron attracting group. Also, from the result of final product, there were 2-acetyl fluorene benzaldehyde.On the basis of these findings, Hydrolysis for the fluorenyl chalcone derivative was proposed a fitting mechanism.

객체지향 기법을 이용한 멀티미디어 데이터 모델링

李相文,黃潤哲 충주대 산업과학기술연구소 1996 産業科學論文集 Vol.4 No.-

In this paper a conceptional model for handling multimedia data like text, image, audio, graphics is presented. After introducing the characteristics of multimedia data for using object - oriented technique in modeling of multimedia data, the necessary conditions for the modeling are derived. Finally an object- oriented multimedia data model which satisfies the condition is proposed.

Server performance analysis for the efficient AAAv6 operation

Hwang, Yoon-Cheol,Jeong, Yoon-Su,Kim, Hyung-Do,Lee, Sang-Ho 충북대학교 컴퓨터정보통신 연구소 2004 컴퓨터정보통신연구 Vol.12 No.3

AAAv6 based on DIAMETER is used in user authentication to satisfy the user's increasing authentication demand and also to supply a safe communication scheme between mobile node and server in the Mobile IP. But there are some problems on the authentication procedures of the DIAMETER, such that security falls down from a loaming service or internet transmission course. To supply user authentication with the mobility among domains by AAAv6-based DIAMETER, efficient capacity allocation among AAA attendant, AAAv, AAAb, AAAh and HA servers is essentially required. In this paper, we elicit an efficient operation indexes for each server of which accomplishes user authentication using a cipher algorithm and optimize conditions for the AAAv6 efficient operation by the index.

A Weight based Distributed Clustering Algorithm for Efficient Management of Mobile Nodes in MANET

Yoon-Cheol Hwang,Min-Seok Kang,Jin-Il Kim 한국정보기술학회 2009 한국정보기술학회논문지 Vol.7 No.6

A mobile ad-hoc network (MANET) is different from a wired network in that it is composed of various mobile nodes, which make the network's topology change unpredictably. Also, those communicate in cooperation with mobile nodes without manager nodes, which control and mediate the mobility of all nodes for stable routing. Therefore, this paper proposes a weight-based distribution clustering algorithm with hierarchical structure that can maintain topology of MANET as stable as possible, thereby optimizing network performance and making efficient resource allocation for mobile nodes. In the proposal algorithm, the initialization overhead has been decreased by allowing clusters to form locally. Furthermore, through applying the concept of pre-clusterhead and distributed gateway, the frequency of re-clustering during maintenance has been decreased, improving its stability compared to traditional clustering algorithms. The results of the simulation showed that the suggested methods enhanced stability and efficiency compared to the traditional methods.

The Korean Society of Gastroenterology & SIDDS 2050 : Slide Session ; K-UG-02 : Upper GI Tract ; Different Expression of Macrophage Migration Inhibitory Factor Levels Depending on H. pylori Positivity in Stomach Cancer and Dysplasia

( Kichul Yoon ),( Nayoung Kim ),( Yong Hwan Kwon ),( Ju Yup Lee ),( Yoon Jin Choi ),( Jae Jin Hwang ),( Hyun Joo Lee ),( Aera Lee ),( Yeon Sang Jeong ),( Hyuk Yoon ),( Cheol Min Shin ),( Young Soo Par 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

Background: Macrophage Migration Inhibitory Factor (MIF) is known as pro-in- fi ammatory and pro-oncogenic cytokine. Its role in gastric cancer has been revealed recently. We evaluated the relationship between MIF and H. pylori in the gastric carcinogenesis. Methods: Human gastric tissue samples from 522 patients were subdivided into 6 groups according to H. pylori infection status and pathologic diagnosis (cancer, dysplasia, or control). Tissue MIF mRNA level was measured by real-time PCR, shown as 2^delta-delta CT (2^ddCT). Results: Gastric cancer tissue expressed signifi cantly higher level of MIF mRNA (n=214, mean±SE; 9.16±1.5) than non-cancer counterpart (n=308, 4.22±0.9, p=0.005). There was no signifi cant difference in MIF mRNA level between H. pylori negative and positive tissues. In subgroup analysis, H. pylori-positive cancer tissue showed signifi cantly higher MIF expression (n=137, 10.27±2.1) than that of H. pylori-positive dysplasia (n=55, 1.91±0.5, p<0.05) or H. pylori-positive control (n=113, 3.29±0.6, p<0.05). However, no such fi nding was noted among the H. pylori-negative cancer/dysplasia/control group. (fi gure) Conclusions: Tissue MIF mRNA level showed signifi cant difference between gastric cancer and dysplasia only in H. pylori-positive group. From these results we can conclude that MIF could be an important factor in the H. pylori induced gastric carcinogenesis. Now the experiments regarding underlying mechanism are undergoing.

모바일 에드혹 네트워크에서 안정성을 향상 시킨 분산 조합 가중치 클러스터링 알고리즘

황윤철(Yoon-Cheol Hwang),이상호(Sang-Ho Lee),김진일(Jin-Il Kim) 한국컴퓨터정보학회 2007 韓國컴퓨터情報學會論文誌 Vol.12 No.1

모바일 에드혹 네트워크는 고정된 인프라의 도움 없이 이동 노드만으로 구성되므로 네트워크의 독립성과 융통성을 높일 수 있으나, 노드의 참여와 이탈의 자유로움 때문에 네트워크를 운영할 때, 망의 형태를 안정적으로 관리하는 것은 무엇보다도 중요하고 어려운 문제이다. 따라서 이러한 문제를 해결하기 위하여, 관리와 안전성에 중점을 둔 분산가중치 클러스터링 알고리즘을 제안한다. 제안된 알고리즘은 초기클러스터 형성시에는 기존의 분산가중치 알고리즘을 사용하고 클러스터 형성 후 이동 노드들로 인해 발생되는 재클러스터링을 최소한으로 줄이기 위해 부클러스터 헤드와 분산게이트웨이라는 개념을 사용한다. 성능 검증을 위해 초기의 오버헤드, 재가입률, 클러스터의 수를 기준으로 기존의 DCA과 WCA 알고리즘과 제안된 알고리즘을 비교, 평가한다. Mobile ad-hoc network(MANET) can increase independence and flexibility of network because it consists of mobile node without the aid of fixed infrastructure. But, Because of unrestriction for the participation and breakaway of node, it has the difficulty in management and stability which is a basic function of network operation. Therefore, to solve those problems, we suggest a distributed weighted clustering algorithm from a manageable and stable point of view. The suggested algorithm uses distributed weighted clustering algorithm when it initially forms the cluster and uses a concept which is distributed gateway and sub-cluster head to reduce the re-clustering to the minimum which occurs mobile nodes after forming the cluster. For performance evaluation, We compare DCA and WCA with the suggested algorithm on the basis of initial overhead, resubscriber rate and a number of cluster.

MANET에서 비정상 노드를 효율적으로 탐지하기 위한 보안 설계

황윤철(Yoon-cheol Hwang) 한국통신학회 2010 韓國通信學會論文誌 Vol.35 No.3

AMIGO 계기함 맞춤형 농사용 분전함 개발에 대한 고찰

황윤철(Yoon-Cheol Hwang),윤석재(Seok-Jae Yoon),황승용(Seung-Yong Hwang),이영섭(Young-Seop Lee) 대한전기학회 2023 대한전기학회 학술대회 논문집 Vol.2023 No.7