• 한국컴퓨터산업학회논문지
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• 제4권4호
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• pp.491-500
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• 2003

네트워크 보안은 정보통신 및 인터넷 기술이 발전함에 따라 그 중요성과 필요성이 더욱 절실해지고 있다. 본 연구에서는 침입차단 시스템, 운영체제 모델과 다양한 네트워크 구성요소들을 모델링 하였다. 각 모델은 MODSIM III 기반의 기본모델(Basic Model)과 결합모델(Compound Model)의 두 가지 유형으로 정의하였다. 대상 네트워크 환경에서 사용한 공격은 서비스 거부공격 형태인 SYN flooding 공격과 Smurf 공격을 발생하였다. 이 공격들에 대하여 패킷 필터 모델에 다양한 보안 정책을 적용하여 시뮬레이션을 실행하였다. 본 연구에서의 시뮬레이션을 통하여 보안정책의 강도를 점점 높였을 때 보안성능이 향상되는 점을 검증하였다.

• Environmental Engineering Research
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• 제21권2호
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• pp.109-120
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• 2016

Conventional treatment techniques cannot meet the stringent modern water quality regulations emanating from the need to provide high quality drinking water. Therefore, a number of studies have suggested low pressure membrane filtration as a worthwhile alternative. However, a major constraint to the extensive use of this technology in low and middle income countries is the high operating and maintenance costs caused by the inherent predisposition to membrane fouling. Notwithstanding, pretreatment of feed water using techniques such as coagulation, adsorption, oxidation and bio-filtration is believed to control fouling. In this review paper, the existing scientific knowledge on membrane fouling and pretreatment techniques for controlling fouling in low pressure membranes is analyzed with the aim of providing new and valuable insights into such techniques, as well as unveiling crucial issues noteworthy for further studies. Among the techniques reviewed, coagulation was observed to be the most cost-effective and will remain the most dominant in the coming years. Although oxidants and magnetic ion exchange resins can also control fouling, the propensity of oxidants to form health treating precursors and the high economic implications of magnetic ion exchange resins will hinder their adoption in developing countries.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.748-751
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• 2006

Positioning accuracy by the Global Positioning System (GPS) is of great concern in a variety of research tasks. It is limited due to error sources such as ionospheric effect, orbital uncertainty, antenna phase center variation, signal multipath, and tropospheric influence. In this study, the tropospheric influence, primarily due to water vapour inhomogeneity, on GPS positioning height is investigated. The data collected by the GPS receivers along with co-located surface meteorological instruments in 2003 are utilized. The GPS receivers are established as continuously operating reference stations by the Ministry of the Interior (MOI), Central Weather Bureau (CWB), and Industrial Technology Research Institute (ITRI) of Taiwan, and International GNSS Service (IGS). The total number of GPS receivers is 21. The surface meteorological measurements include temperature, pressure, and humidity. They are introduced to GPS data processing with 24 troposphere parameters for the station heights, which are compared with those obtained without a priori knowledge of surface meteorological measurements. The results suggest that surface meteorological measurements have an expected impact on the GPS height. The daily correction maximum with the meteorological effect may be as large as 9.3 mm for the cases of concern.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1039-1043
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• 2005

Despite the many significant advances made in robot architecture, the basic approaches are deliberative and reactive methods. They are quite different in recognizing outer environment and inner operating mechanism. For this reason, they have almost opposite characteristics. Later, researchers integrate these two approaches into hybrid architecture. In such architecture, Reactive module also called low-level motion control module have advantage in real-time reacting and sensing outer environment; Deliberative module also called high-level task planning module is good at planning task using world knowledge, reasoning and intelligent computing. This paper presents a framework of the integrated planning and control for mobile robot navigation. Unlike the existing hybrid architecture, it learns topological map from the world map by using MST (Minimum Spanning Tree)-based SOFM (Self-Organizing Feature Map) algorithm. High-level planning module plans simple tasks to low-level control module and low-level control module feedbacks the environment information to high-level planning module. This method allows for a tight integration between high-level and low-level modules, which provide real-time performance and strong adaptability and reactivity to outer environment and its unforeseen changes. This proposed framework is verified by simulation.

• 제어로봇시스템학회논문지
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• 제13권5호
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• pp.434-443
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• 2007

Presently, the exploration of an unknown environment is an important task for thee new generation of mobile service robots and mobile robots are navigated by means of a number of methods, using navigating systems such as the sonar-sensing system or the visual-sensing system. To fully utilize the strengths of both the sonar and visual sensing systems. This paper presents a technique for localization of a mobile robot using fusion data of multi-ultrasonic sensors and vision system. The mobile robot is designed for operating in a well-structured environment that can be represented by planes, edges, comers and cylinders in the view of structural features. In the case of ultrasonic sensors, these features have the range information in the form of the arc of a circle that is generally named as RCD(Region of Constant Depth). Localization is the continual provision of a knowledge of position which is deduced from it's a priori position estimation. The environment of a robot is modeled into a two dimensional grid map. we defines a vision-based environment recognition, phisically-based sonar sensor model and employs an extended Kalman filter to estimate position of the robot. The performance and simplicity of the approach is demonstrated with the results produced by sets of experiments using a mobile robot.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.373-376
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• 2001

In this paper to cope with the reduction of products life-cycle as the variety of products along with the various demands of consumers, a virtual simulator is developed to make the changeover of manufacturing line efficient to embody a virtual simulation similar to a real manufacturing line. The developed virtual simulator can design a layout of a factory and make the time scheduling. Every factory has one simulator so that one product can be manufactured in the factories to use them as virtual factories. We suggest a scheme that heightens the ability to the diversity of manufacturing models by making the information of manufacturing lines and products models to be shared. The developed system embodies a virtual manufacturing line on the simulation using various manipulators and work cells as manufacturing components. we develop a virtual simulator system on Window 98/NT environment of Microsoft, operating system using of the greater part of PC user. Window program have a merit making GUI environment that programmer can use without the expert knowledge about hardware. A suer with the simulator can utilize an interface that makes one to manage the separate task process for each manufacturing module, change operator components and work cells, and easily teach tasks of each task module.

• 한국정보통신학회논문지
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• 제6권8호
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• pp.1259-1268
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• 2002

분산 시스템에서 전체 시스템의 부하 균형을 이루어 시스템의 성능을 향상시키는 것이 주요 목표 중 하나이다. 시스템간의 부하를 균등하게 함으로써 처리기의 가동률을 높이고 작업 반환 시간도 줄일 수 있다. 본 논문은 지식 기반 메카니즘을 이용하여 각 노드에서 과거 및 현재의 정보를 기반으로 추론한 미래 부하상태 정보를 서로 공유하여 최적의 부하 균등화를 이루는 의사 결정 규칙과 정보 교환 규칙을 설계하였다. 성능 평가 결과 각 노드의 가동률이 균등해지고 처리 속도의 향상을 보였으며, 시스템의 신뢰성과 가용성이 향상되었다. 본 논문에서 제안한 기법은 분산 운영 체제의 부하 조절 알고리즘 설계에 활용될 수 있다.

• 대한전기학회논문지:전력기술부문A
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• 제48권6호
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• pp.781-788
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• 1999

In this paper, an expert system is proposed, which can be effectively applied to the large-scale systems with the diversity time constraints, the objectives and the unfixed system structure. The inference scheme of the expert system have the integrated structure composed of the intuitive inference module and logical inference module in order to support effectively the operating constraints of system. The intuitive inference module is designed using the pattern matching or pattern recognition method in order to search a same or similar pattern under the fixed system structure. On the other hand, the logical inference module is designed as the structure with the multiple inference mode based on the heuristic search method in order to determine the optimal or near optimal control strategies satisfing the time constraints for system events under the unfixed system structure, and in order to use as knowledge generator. Here, inference mode consists of the best-first, the local-minimum tree, the breadth-iterative, the limited search width/time method. Finally, the application results for large-scale distribution SCADA system proves that the inference scheme of the expert system is very effective for the large-scale system. The expert system is implemented in C language for the dynamic mamory allocation method, database interface, compatability.

• 복식
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• 제50권4호
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• pp.5-20
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• 2000

Through his geometric design, the Cyprus born fashion designer Hussein Chalayan raises intriguing questions about the very fact of wearing clothes. By purposefully displacing the function of each part of the clothing, such as neck line, hem line, seam, sleeve, etc., Chalayan transforms the meaning of the body that wears clothes. of the human subject as a sovereign possessor of the clothing and the visibility related to fashion. This transformation is achieved by distorting the spaces of his clothing in an unorthodox way. This thesis argues that the significance of such a practice can not be properly understood without relation to the current debate on deconstructionism under way in humanities. Instead of immediately negating the modern frame of Ideas and practices, deconstructionism asks what the assumptions for the modern regime of truth is. In this process, things that lead human beings to sovereign master of knowledge and truth such as reason, subject, body and vision are questioned. In the same context, Chalayan's design not only forces us to rethink the very function of dividing inside and outside by the clothing but also the meaning of boundary operating in numerous sites of modern life. As the human subject is not something pre-given but constructed according to the cultural representation, to which the clothing belongs, fashion can be evaluated to be an active ingredient of constructing the subject. Therefore, Hussein Chalayan's design is at the cross road between the modern and the postmodern regime of fashion.

• Asia pacific journal of information systems
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• 제16권2호
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• pp.183-203
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• 2006

Firms are increasingly adopting online communities-of-practice (CoPs) with strong managerial support in hopes of promoting knowledge sharing and creation within the organization. Excessive managerial concern and sponsoring, however, could harm the spontaneity of CoP participants, which is one of the pivotal characteristics of virtual communities, and in the end, have negative impact on their smooth operation. In this regard, this study examines the factors which affect the stimulation of CoPs and explores the difference in their operating mechanisms under two differing organizational structural settings by the existence of a sponsor. By analyzing 133 samples of CoPs in a globally leading company, this study found that the existence of a sponsor designated by the organization, has serious influence on the working of CoPs, That is, leaders' enthusiasm and the level of off-line activities are critical factors for the stimulation of CoPs which have no sponsor, while in case of CoPs that have their sponsors, neither leaders' enthusiasm nor the level of off-line activities are significantly related to the stimulation of CoPs. At the same time, the performance of CoPs which have their sponsors was found significantly higher than that of CoPs which have no sponsor. These results indicate that firms need to pay special attention to organizational sponsorship when introducing CoPs within their organizations.