컴퓨터 시스템에서의 Deadlock의 성질에 관한 연구

嚴泳翊 단국대학교 1988 論文集 Vol.22 No.-

Deadlock problem has been studied extensively in the past years. Most of these researches have been done in the area of deadlock treatment schemes such as deadlock prevention, avoidence, detection and recovery. But little work has been done for deadlock properities itself. In this paper, we introduced a probablistic model for deadlock. With this model, we formulated the transition probability matrix and analyxed the deadlock properties such as the mean number of steps to deadlock and the expected time to deadlock using the Markov process and queueing theory. These results will be able to given an important implication on the design of deadlock treatment policy.

이동 분산 환경의 클라이언트-서버간 통신량 감소를 위한 캐슁 기법 설계

박재원,엄영익 成均館大學校 科學技術硏究所 1998 論文集 Vol.49 No.1

The callback mechanism is one of the most effective cache consistency strategies to maintain high level consistency and preserve scalability for reliable and fast networks. The development of modern network communication techniques has affected on the advent of portable and mobile computers. With these products, clients can communicate with servers through wireless networks regardless of their locations while they are moving around. The drawback of mobile hosts is that they experiences frequent disconnection of communication and weak connection due to low bandwidth and power. These frequent disconnections result in increasing validation checks for data consistency, and therefore, network traffic and service delay is more increasing. In conclusion, the effect of callback mechanism in these systems is considerably reduced. Mobile hosts have low bandwidths, and are required to effectively use bandwidths to reduce the number of data transfers between clients and servers. The increase of network traffics obstructs the scalability and data availability of mobile environments. This paper proposes caching scheme for reduction of network traffic in mobile computing environments.

이동 컴퓨팅 환경에서 이동 호스트들에 대한 동적 세션 관리 기법

강용혁,김문정,엄영익 成均館大學校 科學技術硏究所 2000 論文集 Vol.51 No.1

Recently, the technical advances in wireless communication technologies and the decreasing size of computer components increase the number of mobile users. In the mobile computing environments wireless links are very restricted resource, so efficient use of wireless links is the heart of an efficient mobile computing environments. This paper proposes a scheme for load reduction of foreign agent by managing the number of registered mobile hosts in a cell. This scheme presents the efficient use of wireless links without the channel rearrangement. Experimental results show that the proposed scheme reduces the number of registered mobile hosts in a cell in proportion to the cell redundancy.

CORBA 環境에서의 學校案內시스템 設計 및 具現

선승상,이은주,엄영익 成均館大學校 科學技術硏究所 1999 論文集 Vol.50 No.1

In the development of distributed object-oriented technology, CORBA, defined as an architecture for providing open object services and the interoperability among CORBA-compliant ORBs, becomes the essential concepts for object services. In this paper, we design and implement the prototype of SKKU-UGS(University Guide System) on the CORBA environments. The SKKU-UGS consists of clients and servers which are interoperable with database server through JDBC-ODBC bridge. By implementing the system based on the Web, SKKU-UGS provides convenience to the users and database managers. The SKKU-UGS also provides portability and interoperability and enhances the reliability of the system by implementing the system on the COMA environments.

이동 컴퓨팅 환경에서의 익명성과 불추적성에 관한 연구

박상윤,최선영,엄영익 成均館大學校 科學技術硏究所 2000 論文集 Vol.51 No.1

In recent years, Internet-based application services on the mobile environment have been activated, and the developments of mobile internet application for user authentication and privacy have been required. Especially, the research for preventing disclosure of identity caused by user mobility is on the progress. In this paper, we introduce the study of an authentication. protocol for anonymity and untraceability supporting the protection of user identity with C5 privacy class and the authenticated secure association mechanism between mobile hosts and remote domains.

THROUGHPUT MAXIMIZING FILE PLACEMENT IN A DISTRIBUTED DATABASE SYSTEMS

Eom, Young Ik 단국대학교 통계문제연구소 1987 數學 및 統計硏究 Vol.15 No.-

Our objective in this paper is showing that transaction throughput can closely approximate the optimum with our dynamic file placement scheme. first, we designed optimal dynamic file placement/replication scheme that minimizes the space time product, which is used as a performance index. The relationship between the file placement scheme for minimizing the space-time product and the scheme for maximizing throughput is studied next.

컴퓨터 시스템에서의 교착상태에 대한 확률적 모델

엄영익(Young Ik Eom),고건(Kern Koh) 한국정보과학회 1989 정보과학회논문지 Vol.16 No.2

최근 컴퓨터 시스템에서는 교착상태라는 현상이 중요한 문제로 대두되면서 이에 대한 연구가 많이 진행되었다. 교착상태에 대한 지금까지의 연구 대상은 주로 실제 시스템에서의 사용을 위한 교착상태 예방, 회피, 발견/복구 등이었으며 교착상태의 본질적인 성질이나 발생과정에는 많은 관심이 미치지 못하였다. 본 논문에서는 교착상태에 대한 확률적 모델을 형성하여 시스템의 전체 상태에 대한 전이 확률 행렬을 만들어 내고 이를 이용하여 교착상태까지의 도달 과정, 도달 시간, 교착상태의 발생 빈도등을 알아낼 수 있는 이론을 연구하였으며 이를 위하여 Markov process 이론과 큐잉이론을 사용하였다. 이의 연구결과는 교착상태 처리기법의 설계나 그의 분석에 많은 도움을 줄 수 있을 것이다. Deadlock problem has been studied extensively in the past years. Most of these researches have been done in the area of deadlock treatment schemes such as deadlock prevention, avoidence, detection and recovery. But, little work has been done for deadlock properties and occurrences. In this paper, we introduced a probabilistic model for deadlock. With this model, we formulated the transition probability matrix and analyzed the deadlock properties such as the mean number of steps to deadlock, the expected time to deadlock and the frequency of deadlock occurrences using the Markov process theory and queueing theory. These results will be able to give an important implication on the design and analysis of deadlock treatment policies.

Effect of Chemical Composition and Antioxidant Activities of Prunus salicina Daeseok, Formosa, and Chuhui Produced in Uiseong

Jung-Young Eom,Hyun-Jin Kim,Jeehye Sung,Ik-Jo Chun,Young-Eun Cho 한국식품영양과학회 2020 한국식품영양과학회 학술대회발표집 Vol.2020 No.10

이동 컴퓨팅 환경을 위한 분산 알고리즘 설계 기법

엄영익(Young Ik Eom),안상준(Sang Joon Ahn) 한국정보과학회 1997 정보과학회논문지 : 시스템 및 이론 Vol.24 No.7

이동 컴퓨팅 환경이란 기존의 분산 컴퓨팅 환경이 모빌 호스트들을 지원할 수 있도록 구성된 환경을 의미한다. 이와 같은 환경에서는 모빌 호스트들이 네트워크와의 접속을 유지한 상태에서 공간의 제약없이 이동할 수 있어야 하며 원하는 곳에서 원하는 정보를 얻을 수 있도록 기술적인 지원이 있어야 한다. 분산 알고리즘의 설계를 위한 분산 상호 배제 기법은 지금까지 주로 정적인 호스트들로만 이루어진 분산 환경을 대상으로 연구되어 왔다. 그러나 새롭게 등장한 이동 컴퓨팅 환경에서는 무선 통신, 휴대성, 이동성 등의 특성을 갖는 모빌 호스트가 존재하게 되므로 이러한 모빌 호스트들을 통합한 새로운 상호 배제 기법을 개발하여야 한다. 지금까지 이동 컴퓨팅 환경을 위한 분산 상호 배제 기법은 토큰 링 구조를 기반으로 설계되었으며 이는 이동한 모빌 호스트의 위치 탐색을 위하여 많은 비용이 소모되는 단점을 지니고 있다. 본 논문에서는 가상의 트리 구조에 기반하여 운영 비용을 줄일 수 있는 분산 상호 배제 기법을 제안 할 뿐만 아니라 노드의 고장이 발생할 경우의 회복 기법을 제안하고, 각각에 대한 비용을 산출한다. The mobile computing environment is a distributed environment that is organized to support mobile hosts. In that environment, mobile hosts should be able to move without any constraints and remain connected to the network even while moving. Also, they should be able to get any necessary information regardless of their current location and time. Distributed mutual exclusion methods for supporting distributed algorithms have hitherto been designed for networks only with static hosts. But, with the emergence of mobile computing environments, a new distributed mutual exclusion method should be developed for integrating mobile hosts with existing distributed systems. Many issues that should be considered stem from three essential properties of mobile computing system such as wireless communication, portability, and mobility. Until now, distributed mutual exclusion methods for mobile computing environments are designed based on a token ring structure, which have the drawbacks of requiring high costs in order to locate mobile hosts. In this paper, we propose not only a distributed mutual exclusion method that can reduce such costs by structuring the entire system as a tree-based logical structure but also recovery schemes that can be applied when node failures occur. And we evaluate the operation costs in each case.

의성 자두 대석조생, 후무사, 추희의 영양성분과 항산화 활성 비교 분석

엄정영(Jung-Young Eom),김현진(Hyun-Jin Kim),최상헌(Sang-Hun Choi),서현주(Hyun-Ju Seo),전익조(Ik-Jo Chun),성지혜(Jeehye Sung),임재환(Jae Hwan Lim),권인숙(In-Sook Kwun),조영은(Young-Eun Cho) 한국식품영양과학회 2021 한국식품영양과학회지 Vol.50 No.6

본 연구는 동양계 자두 품종 중에서 의성 자두인 대석조생, 후무사, 추희 품종의 영양성분 및 항산화 활성을 평가하였다. 총 식이섬유는 대석조생> 후무사> 추희 순으로 대석조생이 가장 높았다. 칼슘 함량에서는 대석조생> 추희> 후무사 순으로 대석조생이 칼륨, 칼슘, 인의 함량이 모두 높은 것으로 나타났다. 총 폴리페놀 함량은 추희, 대석조생이 유의적으로 높았고 총 플라보노이드 함량은 대석조생이 유의적으로 가장 높았다. 항산화 활성은 대석조생> 후무사> 추희 순으로 대석조생이 가장 높았다. 따라서 동양계 자두인 의성 자두는 식이섬유 함량이 높고 열량이 낮으며, 높은 항산화 활성을 갖고 있어 다양한 건강 기능성 식품 소재로 활용도가 높을 것으로 사료된다. In this study, we investigated the chemical properties and antioxidant activities of Prunus salicina cultivars. We analyzed the nutritional ingredients, minerals, total polyphenols, total flavonoids, total fiber, and antioxidant activities of Prunus salicina Daeseok, Formosa, and Chuhui produced in Uiseong. There were no significant differences in the carbohydrate composition i.e., fructose, sucrose, and maltose between Prunus salicina Daeseok, Formosa, and Chuhui. Trans fat and cholesterol were not detected in any of the cultivars. The highest contents of P, K, and Ca were observed in the descending order of Prunus salicina Daeseok, Formosa, and Chuhui. In addition, the highest contents of total polyphenol and flavonoid were significantly detected in Prunus salicina Daeseok. Furthermore, the highest content of total fiber was observed in Prunus salicina Daeseok and Formosa. The highest antioxidant activities were observed in Prunus salicina Daeseok compared to Formosa and Chuhui. Taken together, these results suggest that Prunus salicina Daeseok produced in Uiseong could help develop antioxidant products.