• Proceedings of the CALSEC Conference
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• 1998.10a
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• pp.95-104
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• 1998

Nowadays, document management system is used to share the information using intranet in some enterprises. But for enterprise that is to share information with other enterprises, a simple information sharing environment like homepage or email is used. The goal of CALS is to increase productivity through rapid exchange of shared information between enterprises. CITIS is a software infrastructure in CALS and service standard to share the CALS data among business organizations. CITIS can be used as a software infrastructure for constructing virtual enterprise in the internet. In this paper, we design and implement CITIS prototype on the internet. Java is selected as an implementation language fer its portability and web-based characteristics. CORBA is an communication middleware for distributed objects.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.754-756
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• 2005

현대는 실제와 같은 환경을 재현할 수 있도록 제작된 시뮬레이터를 사용하여 실제 훈련을 대체하고 있다. 그러나 많은 사용자들은 이미 개발된 이종의 시뮬레이터들을 하나로 묶어 연동할 필요성을 느끼게 되었고, 이에 따라 다양한 형태의 상호작용이 수반되는 시뮬레이션에 대한 요구를 만족하는 대규모 분산가상환경(large-scaled distributed virtual environment)을 개발하려는 움직임이 크게 늘게 되었다. 이러한 요구를 바탕으로 등장한 것들 중 하나가 HLA이다. High Level Architecture (HLA)는 미국방성에서 모델과 시뮬레이션에 공통의 구조와 인터페이스를 제공하기 위해 개발된 통합 구조이다. HLA는 분산 컴퓨팅 환경에서 각각의 시뮬레이터들이 정보를 교환 할 수 있게 해줌으로써 하나의 통합 시뮬레이션 시스템을 구축하게 해준다. HLA는 크게 Object Model Template (OMT)와 Run-Time Infrastructure (RTI)로 구성되어 있으며, 이를 통하여 공통된 구조와 상호 작용 환경을 제공한다. 각각의 시뮬레이터들은 RTI를 통하여 Federation에 참여하고 선별적으로 원하는 정보를 주고받으며 하나의 통합 시뮬레이션을 이루게 된다. 본 논문에서는 분산 컴퓨팅 환경에서 이기종의 3차원 영상 시뮬레이터들에 HLA 인터페이스를 삽입하고 3차원 영상 시뮬레이션에 적합하게 개발된 공통 구조인 FOM 제공하여 하나의 통합 가상훈련 시스템을 구축하였다. 이 시스템은 현재 KA-32 헬기 시뮬레이터 영상 프로그램 제작에 적용되어있다.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.645-654
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• 1995

A distributed DBMS integrates local schemas that are independently designed, maintained, and managed by different users at each site providing a global virtual schema. This global schema supports users at a specific site to transparently utilize local database at different sites. The security features of the local schema should also not be changed in the global schema integrating security features of each local schema. Researches on the integration of security features into local schema in distributed DBMS environment, however, are very rate. This pater using the multilevel secure object-oriented database model(as the model for the definition of a local schema in distributed environment) which is an extension of the object-oriented models. It also suggests eight integration methods that can maintain the security features of local schemas. The eight methods are classified by the object classes and by relationships among them.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.791-797
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• 2014

In order to create an environment for Apache Hadoop for parallel distributed processing system of Bigdata, by connecting a plurality of computers, or to configure the node, using the configuration of the virtual nodes on a single computer it is necessary to build a cloud fading environment. However, be constructed in practice for education in these systems, there are many constraints in terms of cost and complex system configuration. Therefore, it is possible to be used as training for educational institutions and beginners in the field of Bigdata processing, development of learning systems and inexpensive practical is urgent. Based on the Raspberry Pi board, training and analysis of Big data processing, such as Hadoop and NoSQL is now the design and implementation of a learning system of parallel distributed processing of possible Bigdata in this study. It is expected that Bigdata parallel distributed processing system that has been implemented, and be a useful system for beginners who want to start a Bigdata and education.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1938-1943
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• 2005

Network human-robot interface is an important research topic. In home application, users access the robotic system directly via voice, gestures or through the network. Users explore a system by using the services provided by this system and to some extend users are enable to participate in a service as partners. A service may be provided by a robot, a group of robots or robots and other network connected systems (distributed sensors, information systems, etc). All these services are done in the network environment, where uncertainty such as the unstable network connection, the availability of the partners in a service, exists. Moreover, these services are controlled by several users, accessing at different time by different methods. Our research aimed at solving this problem to provide a high available level, flexible coordination system. In this paper, a multi-agent framework is proposed. This framework is validated by using our new concept of slave agents, a responsive multi-agent environment, a virtual directory facilitator (VDF), and a task allocation system using contract net protocol. Our system uses a mixed model between distributed and centralized model. It uses a centralized agent management system (AMS) to control the overall system. However, the partners and users may be distributed agents connected to the center through agent communication or centralized at the AMS container using the slave agents to represent the physical agents. The system is able to determine the task allocation for a group of robot working as a team to provide a service. A number of experiments have been conducted successfully in our lab environment using Issac robot, a PDA for user agent and a wireless network system, operated under our multi agent framework control. The experiments show that this framework works well and provides some advantages to existing systems.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.2
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• pp.219-230
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• 2002

One of the most important functions digital libraries need to offer is to help users find necessary information in a distributed environment in the most efficient and effective manner. In order to meet the goal, it is desirable to link scattered pieces of information and present them as a logically coherent whole when the user wants it, so that he or she doesn't need to know their physical location. The virtual document is an integrated document that the total or part of the physical documents stored in a specific repository are linked dynamically. Our MIRAGE-III digital library system provides a content-based retrieval of physical documents and the virtual documents in XML. This system provides a retrieval of partial documents, attributes and hierarchical structures and linked-documents based in structured documents like XML or SGML. In this paper we describe a methodology of design and implementation of the query processor and retrieval server in the MIRAGE-III digital library system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.211-216
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• 2011

Networked virtual environments (NVEs) are distributed systems where geographically dispersed users interact with each other in virtual worlds by exchanging network messages. Massively Multiplayer Online Game (MMOG) is one of diverse applications where more than hundreds of users enjoy experiencing virtual worlds. A limited area called area of interest (AOI) in MMOG is reduced the load caused by message exchange between users. Voronoi-based Overlay Network (VON) is proposed to reduce the bandwidth consumption in P2P environments and Vorocast also is made using message forwarding in VON. We propose a dynamic AOI management method that solves problems such as a consistency and latency due to forwarding position updates to neighbor nodes from the message originator in forwarding scheme. Our scheme provides the consistency and reduces latency by combining direct connection scheme and Vorocast scheme compared to existing schemes. The communication between a user and users existing in center circle within AOI of the user is directly connected and the communication between the user and users existing outside the center area within AOI is using Vorocast scheme. The proposed model is evaluated through simulations.

• The Journal of Korean Physical Therapy
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• v.31 no.2
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• pp.67-75
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• 2019

Purpose: Patients with brain damage suffer from limitations in performing the activities of daily living (ADL) because of their motor function and visual perception impairment. The aim of this study was to help improve the motor function and visual perception ability of patients with brain damage by providing them with virtual reality-based contents. The usability results of the patients and specialists group were also evaluated. Methods: The ADL contents consisted of living room, kitchen, veranda, and convenience store, similar to a real home environment, and these were organized by a rehabilitation specialist (e.g., neurologist, physiotherapist, and occupational therapist). The contents consisted of tasks, such as turning on the living room lights, organizing the drawers, organizing the kitchen, watering the plants on the veranda, and buying products at convenience stores. To evaluate the usability of the virtual reality-based visual cognitive rehabilitation service, general elderly subjects (n=11), stroke patients (n=7), stroke patients with visual impairment (n=4), and rehabilitation specialists (n=11) were selected. The questionnaires were distributed to the subjects who were using the service, and the subjective satisfaction of individual users was obtained as data. The data were analyzed using SPSS 21.0 software. The general characteristics of the users and the evaluation scores of the experts were analyzed using descriptive statistics. Results: The usability test result of this study showed that the mean value of the questionnaire related to content understanding and difficulty was high, between 4-5 points. Conclusion: The virtual reality rehabilitation service of this study is an efficient service that can improve the function, interest, and motivation of stroke patients.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.927-934
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• 2002

In order to provide various multimedia services in a wireless network, the call admission control for wireless channels should be resolved at the time of call setup and handoff by moving mobile terminal. In this paper. we propose a reliable DCAC( Distributed Call Admission Control)scheme using virtual cluster concept. The proposed DCAC scheme considers the state of $1^{st}$ and $2^{nd}$ adjacent cells to provide a reliable call handling. The proposed scheme is analyzed by simulations and mathematical methods.

• Journal of Engineering Education Research
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• v.10 no.3
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• pp.79-92
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• 2007

To enhance the excellence, effectiveness and economical efficiency in the learning process, we implement a hybrid educational system for engineering experiments where web-based virtual laboratory systems and distance education systems are properly integrated. In the first stage, we designed client/server distributed environment and developed web-based virtual laboratory systems for digital systems and electrical/electronic circuit experiments. The proposed virtual laboratory systems are composed of four important sessions and their management system: concept learning session, virtual experiment session, assessment session. With the aid of the management system every session is organically tied up together to achieve maximum learning efficiency. In the second stage, we have implemented efficient and cost-effective distant laboratory systems for practicing electric/electronic circuits, which can be used to eliminate the lack of reality occurred during virtual laboratory session. The use of simple and user-friendly design allows a large number of people to access our distant laboratory systems easily. Thus, self-guided advanced training is available even if a lot of expensive equipment will not be provided in the on-campus laboratories. The proposed virtual/distant laboratory systems can be used in stand-alone fashion, but to enhance learning efficiency we integrated them and developed a hybrid educational system for engineering experiments. Our hybrid education system provides the learners with interactive learning environment and a new approach for the delivery of engineering experiments.