• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.74-76
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• 2000

공간 데이터와 같은 대용량의 데이터를 처리하는 시스템이나 다수의 클라이언트의 요구가 발생하는 시스템에서는 데이터에 대한 처리 비용 및 전용 비용으로 인한 서버 사이드의 병목 현상 및 질의 처리 속도의 저하라는 문제점을 갖는다. 본 논문에서는 이러한 문제점을 개선하기 위한 방법으로 미들웨어인 C-C Connector의 Method 및 프로토콜을 제안한다. 제안하는 C-C(Client To Client) Connector는 질의의 분석과 CIT(Client Information)의 검색을 통하여 인접한 클라이언트들의 캐쉬 데이터를 이용한 질의 처리의 가능 여부를 판단하며 인접 클라이언트와 요구 클라이언트 사이의 Connection을 형성함으로서 클라이언트-클라이언트의 질의 처리 및 데이터 전송 기능을 지원한다. 그리고 이러한 기능의 지원을 위한 서버, C-C Connector, 클라이언트 사이에서 수행되어지는 질의 처리의 프로토콜을 정의한다. 제안된 C-C Connector의 Method 및 프로토콜은 서버 사이드의 처리 비용을 현재 서버에 접속중인 클라이언트들에게 분배함으로서 서버 사이드의 병목현상과 질의 처리 시간의 지연이라는 문제점을 개선할 수 있으며 클라이언트 사이드에서의 반응 속도의 향상과 현재 연결된 시스템의 처리 성능을 최대한 활용할 수 있다는 장점을 갖는다.

• The KIPS Transactions:PartA
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• v.18A no.1
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• pp.25-32
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• 2011

NoC is actively being studied recently in order to overcome the limitations of shared-bus architecture. We proposed an NoC architecture which employs a buffer that plays a similar role of a proxy server in a computer network to enhance the communication efficiency of NoC architecture. In the proposed NoC architecture, whenever the master has a difficulty in communicating with the slave directly, the master communicates with the proxy server which is able to communicate with the slave on behalf of the master. With the proposed scheme in NoC, we can increase the speed and the bandwidth of communication channel. The experimental results showed that overall communication efficiency was significantly improved by sending the packets to the proxy server rather than holding them in the switch buffer.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.37-44
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• 2015

A queueing system with 2 parallel workstations is common in the field. Typically, the workstations have different features in terms of the inter arrival times of customers and the service times for the customers. Computer simulation study on the optimal server allocation for parallel heterogeneous queueing systems with fixed number of identical servers is presented in this paper. The queueing system is optimized with respect to minimizing the weighted system time of the customers served by 2 parallel workstations. The system time formula for the M/M/c systems in Kendall's notation is known. Thus, we first compute the optimal allocation for parallel M/M/c systems, comparing the results with those from the computer simulation experiments, and have the same results. The CETI rule is devised through optimizing M/M/c cases, which allocates the servers based on Close or Equal Traffic Intensities between workstations. Traffic intensity is defined as the arrival rate divided by the service rate times the number of servers. The CETI rule is shown to work for M/G/c, G/M/c queueing systems by numerous computer simulation experiments, even if the rule cannot be proven analytically. However, the CETI rule is shown not to work for some of G/G/c systems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1141-1151
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• 2018

In an APT attack, the communication stage between infected hosts and C&C(Command and Control) server is the key stage for intrusion into the attack target. Attackers can control multiple infected hosts by the C&C Server and direct intrusion and exploitation. If the C&C Server is exposed at this stage, the attack will fail. Therefore, in recent years, the Domain Generation Algorithm (DGA) has replaced DNS in C&C Server with a short time interval for making detection difficult. In particular, it is very difficult to verify and detect all the newly registered DNS more than 5 million times a day. To solve these problems, this paper proposes a model to judge DGA-DNS detection by the morphological similarity analysis of normal DNS and DGA-DNS, and to determine the sign of APT attack through it, then we verify its validity.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.721-723
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• 2001

월드 와이드 웹(WWW)서비스는 상당한 지연이 발생할 것이라고 예상하는 수준까지 성장해 왔다. 이런 이유로 웹 지연시간을 줄이기 위한 기술들이 중요하게 되었다. 프록시 서버 캐시는 느린 응답시간과 네트워크 정체와 같은 문제들을 해결하기 위해서 제안되었는데 이런 프록시 서버들을 계층적으로 구성하는 방법에 대한 많은 연구가 있었다. 하지만 이런 일반적인 웹캐싱 계층 기법들은 프록시 서버들간의 통신 경로에 있어서 유연성을 제공하지 못하는 정적 구조의 기법이다. 이런 정적인 기법에서의 단점을 해결하기 위해서 캐싱 지역 프로토콜(Caching Neighborhood Protocol)이 제안되었고 이 CNP는 요청들을 협력적으로 처리하는 일련의 프록시 서버의 집합이 매 단일 요청에 대해서 바뀔 수 있고 이에 따라서 요청 처리 경로가 다양해 질 수 있기 때문에 정적 구조 기법과는 반대인 동적 구조 기법이다. 하지만 이러한 동적 웹 캐싱 계층 구조인 CNP에서는 각 웹서버를 대표하는 캐싱 대리인(Caching Representatives)에 대한 웹문서의 링크참조정보와 부하정보를 고려하지 않았기 때문에 사용자에게 빠른 응답시간을 제공하지 못하는 단점이 있다. 본 논문에서는 최근에 제안되었던 프록시 서버들을 동적 웹캐싱 계층으로 구성한 CNP와 새로 추가된 C-Rep의 상태정보를 이용해서 새로운 요청 라우팅 기법을 제안하였다. 제안한 기법은 이런 C-Rep의 상태정보를 이용하여 응답시간의 향상과 C-Rep의 부하를 분산시킬 수 있었다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.131-133
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• 1999

유니뷰(uniview) 시스템은 이기종 분산환경에서 동작하는 프로그램을 디버깅하는 도구로서 시스템 종속적인 부분은 디버깅 서버로 분리시킴으로써 사용자 인터페이스의 이식성과 개발의 효율성을 증대시킨 클라이언트/서버 시스템이다. 현재 유니뷰 시스템은 GNU 디버거인 gdb를 기반으로 동작하며 C 및 C++언어를 지원한다. 본 논무에서는 자바 어플리케이션 디버깅을 지원하기 위한 유니뷰 jdb 서버와 서버 시스템 개발 과정 중 프로그램 수행 제어 명령에 대한 설계 및 구현에 대해 설명한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.203-211
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• 2013

Due to the rapid growth of mobile devices and applications, mobile cloud computing is becoming an important platform in the development of cloud services. However, the mobile cloud computing is facing many challenges in terms of the computing resources and communications. One of them is the performance issue between mobile devices and cloud server. In the paper, we implemented a hadoop-based android mobile application, called mobile TPC-C, and used it for evaluating the performance aspect between mobile devices and cloud server. The mobile TPC-C was implemented based on the existing TPC-C, to make it possible to execute on top of android mobile devices. The performance measurement using mobile TPC-C was executed on various transactions while changing the number of mobile clients. By comparing it to the evaluation on the personal PC, we tried to point out the important aspects affecting the performance improvement between mobile clients and cloud server.

• The KIPS Transactions:PartC
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• v.12C no.4 s.100
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• pp.603-608
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• 2005

Disk I/O is a major performance bottleneck of web proxy server. Today's most web proxy sowers are design to run on top of a general purpose file system. But general purpose file system can not efficiently handle web cache workload, small files, leading to the performance degradation of entire web proxy servers. In this paper we evaluate the performance potential of raw disk to reduce disk I/O overhead of web proxy servers. To show the performance potential of raw disk, we design a storage management system called Block-structured Storage Management System (BSMS). And we also actually implement web proxy server that incorporate BSMS in Squid. Comprehensive experimental evaluations show that raw disk can be a good solution to improve disk I/O performance significantly for web proxy servers.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.797-806
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• 1995

The Client-Server model is a computing technique that efficiently uses distributed resources via networks. But, generating an application using Client- Server model requires many different expertises to developers in comparison to that of using the centralized computing method. That is, and application developer must be familiar with network programming and GUI(Graphical User Interface) techniques in addition to conventional programming skills. Accordingly, the time and man power have been issued for building a Client-Server system. To alleviate these problem, the Client-Server applications development tools are needed To meet such a need, we developed a GUI based tool, called Hanuri/C, for generating Client-Server application programs. In comparison to existing Client-Server tools, Hanuri/C is reinforced Multimedia facilities, Hanuri/C is reinforced Multimedia facilities. Hanuri/C is considered as a front-end part of distributed system software. That is, Hanuri/C is a Client-Server tool similar to Forth Generation Language(4GL) supporting multimedia application on top of the Distributed Computing environment(DCE). In this paper, we present the design and implementation method of the middleware part of Hanuri/c.

• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.1940-1947
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• 1997

The paper describes the design and implementation of Auto-Presentation Feature, Hanuri/C, as Client/Server tool. Hanuri/C provides editing functions for the sequence, period, type, and repeating number of auto-presentation. With the pre-fixed sequences users can get automated presentations through Hanuri/C. The proposed auto-presentation function provides an ability to automatically present the data in the database system without user intervention.