• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제10권2호
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• pp.81-88
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• 2006

슈퍼 컴퓨터의 등장으로 기존에는 풀지 못했던 과학적, 학술적인 문제들이 대부분 해결되었지만 슈퍼 컴퓨터 자체의 막대한 비용 문제는 여전히 풀지 못한 숙제로 남아 있다. 이에 일반 사용자의 컴퓨터의 유휴 자원을 통합하여 협업하는 그리드 컴퓨팅이라는 개념이 등장하였다. 한편 분산되어 있는 이기종의 시스템의 자원을 통합하여 관리하기 위해서 연결 지향적인 프로토콜들이 사용되었지만, 다른 프로토콜끼리는 호환성이 없는 등의 문제가 존재한다. 본 논문에서는 플랫폼 독립적인 XML 기반의 SOAP을 사용하는 웹 서비스를 이용하여 그리드 네트워크의 성능 정보를 관리해주는 시스템을 제안한다.

• 한국정보처리학회논문지
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• 제3권4호
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• pp.961-968
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• 1996

무궁화 위성 과제 중에서는 지구국 시스템에서 위성 링크를 통한 LAN 상호간의 접속을 제공하기 위한 시범위성 네트워크 모듈의 구현을 수행하였다. 이 시범 네트워 크는 위성을 통하여 다양한 응용들에 대한 수행을 검증하기 위한 시험을 지원할 수있 다.본 논문에서는 위성 전송시의 장단점을 고려하여 충분히 응용할 수 있는 위성-LAN 접속 구조를 제안하였다. 본 네트워크 구조는 두개의 노드에서 복수의 논리 접속을 수행하는 연결 중심형인 위성 프로토콜을 사용함으로서 높은 데이타 전송과 위성 접속 에러율에 대한 높은 성능을 제공한다. 또한, 프로토콜 변환 방법에 따라 라우터 접속을 수행할수 있다. 위성과 네트워크 접속의 구조는 4W 고출력 증폭기가 장착된 1.8m의 안테나, 위성통신용 모뎀, 위성 네트워크 접속 장치가 설계되었다. 이 시스 템은 최대 1.544 Mbps의 전송 속도를 자원할수 있으며 네트워크 관리면에서도 우수 하게 동작하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.25-28
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• 1999

Consider connection-oriented wireless cellular net-works. To establish a circuit or virtual circuit in such a network, a paging message is broadcast over a region at which the destined mobile station is presumed to reside, (identified as a paging area). For an effective paging mechanism, it is desirable to provide the location information of mobile stations to the network. In this paper, we consider a mobile controlled location update scheme under which each mobile station periodically reports its current location information to the network by using an inherent timer (without measuring the power of signals transmitted from base stations). Based on the latest information about a mobile station's location, a paging area is selected to page the mobile station. Note that under this scheme, a mobile station may not yet have reported its location change while sojourning out of the current paging area. In such situation, the mobile station can not receive a paging message destined to it. Frequent location updates can reduce the paging failure rate incurred by mobile stations'sojourning out of the paging area. However, larger bandwidth is needed for location update as the location update rate is increased. On the other hand, as the size of the paging area is increased, the paging failure rate is decreased, while larger bandwidth is required for paging. Thus, we first present a model for mobility, paging and location update processes, and secondly investigate the effect of network parameters on the paging failure rate and the amount of bandwidth used for paging and location update. Finally, we formulate problems to find proper values for the location update rate and paging area size under the constraints on the bandwidth usage levels for location update and paging.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제2권2호
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• pp.63-81
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• 2008

WiMAX has been introduced as a competitive alternative for metropolitan broadband wireless access technologies. It is connection oriented and it can provide very high data rates, large service coverage, and flexible quality of services (QoS). Due to the large number of connections and flexible QoS supported by WiMAX, the uplink access in WiMAX networks is very challenging since the medium access control (MAC) protocol must efficiently manage the bandwidth and related channel allocations. In this paper, we propose and investigate a cost-effective WiMAX bandwidth management scheme, named the WiMAX partial sharing scheme (WPSS), in order to provide good QoS while achieving better bandwidth utilization and network throughput. The proposed bandwidth management scheme is compared with a simple but inefficient scheme, named the WiMAX complete sharing scheme (WCPS). A maximum entropy (ME) based analytical model (MEAM) is proposed for the performance evaluation of the two bandwidth management schemes. The reason for using MEAM for the performance evaluation is that MEAM can efficiently model a large-scale system in which the number of stations or connections is generally very high, while the traditional simulation and analytical (e.g., Markov models) approaches cannot perform well due to the high computation complexity. We model the bandwidth management scheme as a queuing network model (QNM) that consists of interacting multiclass queues for different service classes. Closed form expressions for the state and blocking probability distributions are derived for those schemes. Simulation results verify the MEAM numerical results and show that WPSS can significantly improve the network’s performance compared to WCPS.

• 한국지능시스템학회논문지
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• 제13권2호
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• pp.148-153
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• 2003

서비스 거부 공격은 침입을 위한 침입시도 형태로 나타나며 대표적인 공격으로 Syn Flooding 공격이 있다. Syn Flooding 공격은 신뢰성 및 연결 지향적 전송서비스인 TCP의 종단간에 3-way handshake의 취약점을 이용한 공격이다. 본 논문에서는 네트워크 기반의 지능적 침입 방지 모델을 제안한다. 제안하는 모델은 Syn Flooding 공격을 탐지하기 위하여 패킷 정보를 수집하고 분석한다. 이 모델은 퍼지인식도(Fuzzy Cognitive Maps)를 적용한 결정모듈의 분석 결과를 활용하여 서비스 거부 공격의 위험도를 측정하고 공격에 대응하도록 대응모듈을 학습시킨다. 제안하는 모델은 Syn Flooding 공격의 위험을 격감 또는 방지하는 네트워크 기반의 지능적 침입 방지 모델이다.

• Ocean and Polar Research
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• 제34권3호
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• pp.349-364
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• 2012

This study focuses on systematic structure of factors, which affect commercialization of ocean science and technology (OST), applying both grounded theory methodology (GTM) and semantic network analysis methodology (SNAM) by using in-depth interviews with 8 specialists previously experienced in the same field. This study further focuses on clarification of the distinctiveness and universality of commercialization factors on OST by comparatively analyzing on the commercialization factors of general sciences and technologies. Using SNAM, it was determined that commercialization success required connected support system, government support, technology marketing, technology power and characteristics of commercialized entities, which were identified as dominant factors. GTM presented an outcome that connected support systems among participants in commercialization and found that research institute strategies are significant factors in the core phenomenon of commercialization, while technology marketing, technology power and market-oriented technology are important conditions. In addition, the factors of technology, market, connection of participants and government support of commercialized entities are shown as equally important factors for commercialization of ocean science and technology. Secondly, SNAM results indicate that ocean science characteristics depend on a network of government support, research institute strategy, organization and manpower, capital power, and technology marketing, as these ocean science characteristics have been identified as significant factors in the GTM study. It has been determined that technology, market and government support should be connected in order for commercialization of ocean science and technology (OST). Moreover, commercialization methods, applied to the marketing of commercialization of ocean science and technology is differentiated from others since commercialization success is more relevant to these factors.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2003년도 추계종합학술대회 논문집
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• pp.347-351
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• 2003

네트워크 통신을 기반으로 한 영상 회의 및 세미나, 강의에서는 영상/음성뿐만 아니라 프리젠테이션 제시 또한 중요한 요소로 작용하고 있다. 전형적인 세미나 또는 회의, 강의에서 사용되는 흑판을 촬영하여 영상 전송 기능을 그대로 이용하는 프리젠테이션 제시 기법은 고해상도의 영상 기술이 필요하고, 촬영기술의 기능까지 요구되므로 원격의 환경에서 큰 장애 요인이 된다. 본 논문에서는TCP기반의 연결 지향형 소켓을 이용한 효과적인 멀티미디어 프리젠테이션을 공유하기 위한 실시간 멀티미디어 공유 보드시스템을 구현한다. 이 시스템은 시스템 구축에 수반하는 비용을 감소할 수 있으며 데이터 신뢰성 및 상호 작용을 향상시키고, 프리젠데이션 지연 시간을 최소화할 수 있다.

• 한국통신학회논문지
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• 제32권12B호
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• pp.800-808
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• 2007

무선 데이터 통신 기술의 발전으로 모든 IP 기반의 네트워크는 유선과 무선이 혼합된 형태의 네트워크로 진화해 나갈 것이다. TCP는 연결형의 신뢰성 있는 전송계층 프로토콜로서 모든 유선 네트워크의 실질적 표준으로 사용되고 있다. 그러나, TCP의 혼잡제어 알고리즘이 비트 에러, 링크의 단절, 경로의 변화로부터 혼잡을 구분하지 못하기 때문에 TCP는 모바일 ad-hoc 네트워크의 성능 저하를 초래한다. 본 논문에서 TCP의 이론적인 특징을 고찰하고, 모바일 ad-hoc 네트워크에서 TCP의 성능이 저하됨을 ns2를 이용하여 분석하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권4호
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• pp.671-690
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• 2010

The continuous growth of attacks in the Internet causes to generate a number of rules in security devices such as Intrusion Prevention Systems, firewalls, etc. Policy anomalies in security devices create security holes and prevent the system from determining quickly whether allow or deny a packet. Policy anomalies exist among the rules in multiple security devices as well as in a single security device. The solution for policy anomalies requires complex and complicated algorithms. In this paper, we propose a new method to remove policy anomalies in a single security device and avoid policy anomalies among the rules in distributed security devices. The proposed method classifies rules according to traffic direction and checks policy anomalies in each device. It is unnecessary to compare the rules for outgoing traffic with the rules for incoming traffic. Therefore, classifying rules by in-out traffic, the proposed method can reduce the number of rules to be compared up to a half. Instead of detecting policy anomalies in distributed security devices, one adopts the rules from others for avoiding anomaly. After removing policy anomalies in each device, other firewalls can keep the policy consistency without anomalies by adopting the rules of a trusted firewall. In addition, it blocks unnecessary traffic because a source side sends as much traffic as the destination side accepts. Also we explain another policy anomaly which can be found under a connection-oriented communication protocol.

• 대한안전경영과학회지
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• 제6권3호
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• pp.109-120
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• 2004

As an information-oriented era arrives, an environmental change of Internet marketing is going with high speed and such open door around the countries is providing worldwide companies with a new business opportunity. Now, Internet is a new communication tool for global network and is emerging as a new e-commerce market. Also, this trend is having an effect upon online site that sell crafts. Hence, this study aims to select artshop, which simultaneously operate off line and online while sell crafts, to research the present status, and analyze the problems to suggest the activation plans for effective Internet commerce. Accordingly, this study suggested six models for the settlement of these problem s and the activation plans as following: offer of the various works and the contents, security of price competition, reinforcement of marketing, establishment of brand recognition, management of customers and settlement of payment ways etc. The commerce of crafts in the artshop is only early stage today, but it is expected to grow into an universal connection way of information and buying which transcend space and to be briskly used for securing the competition of crafts in 21century.