• 한국안전학회지
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• 제24권6호
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• pp.1-6
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• 2009

This study describes a construction procedure of 3D virtual space using the NGIS data and its application to simulation. 3D space topography is modeled by using DEM consisted with triangular regular network. The elevations of nodal points of DEM are calculated through the interpolation with contour line and elevation points from the NGIS. Also, data for 2D roads and their environments, such as trees, lamps, and traffic signals, were extracted from the NGIS and projected on the DEM surfaces to get 3D virtual space. To give a reality to 3D virtual space and accelerate its graphic speed, data were converted into the directX format. It is believed that the virtual space constructed in this work can be applicable to the ubiqutous because DEM data can be converted to the AutoCAD format and ASCII code.

• 대한인간공학회지
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• 제16권2호
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• pp.101-122
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• 1997

Our recent work on virtual environments and virtual displays is reviewed, including our efforts to establish the Virtual Environment Research, Interactive Technology, And Simulation (VERITAS) facility and our research on spatial hearing. VERITAS is a state-of -the-art multisensory facility, built around the ${CAVE}^{TM}$ technology. High-quality 3D audio is included and haptic interfaces are planned. The facility will support technical and non-technical users working in a wide variety of application areas. Our own research emphasizes the importance of auditory stimulation in virtual environments and complex display systems. Experiments on auditory-aided visual target acquistion, sensory conflict, sound localization in noise, and loxalization of speech stimuli are discussed.

• 콘크리트학회논문집
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• 제11권5호
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• pp.79-88
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• 1999

The purpose of this paper is to develop a mathematical expression for computing crack angles based on reinforcement volumes in the longitudinal and transverse directions, member end-fixity and length-to-width aspect ratio. For this a reinforced concrete beam-column element is assumed to possess a series of potential crack planes represented by a number of differential truss elements. Depending on the boundary condition, a constant angle truss or a variable angle truss is employed to model the cracked structural concrete member. The truss models are then analyzed using the virtual work method of analysis to relate forces and deformations. Rigorous and simplified solution schemes are presented. An equation to estimate the theoretical crack angle is derived by considering the energy minimization on the virtual work done over both the shear and flexural components the energy minimization on the virtual work done over both the shear and flexural components of truss models. The crack angle in this study is defined as the steepest one among fan-shaped angles measured from the longitudinal axis of the member to the diagonal crack. The theoretical crack angle predictions are validated against experimentally observed crack angle reported by previous researchers in the literature. Good agreement between theory and experiment is obtained.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2630-2637
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• 2020

The structure design of divertor Multi-Functional Maintenance Platform (MFMP) actuated by hydraulic system for China Fusion Engineering Test Reactor (CFETR) was introduced in this paper. The model of MFMP was established according to maintenance requirements. In this paper, Newton-Euler method and the improved virtual work principle were used, the equivalent driving force of each actuator was obtained through the equivalent Jacobian inverse matrix derived from velocity relationship among the components. The accuracy of the model was verified by ADAMS simulation. The stability control of the heavy-duty components driven by hydraulic cylinders based on Newton-Euler method and improved virtual work principle was established.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2676-2681
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• 2003

The Haptic Exploration Laboratory at The Johns Hopkins University is currently exploring many problems related to haptics (force and tactile information) in human-machine systems. We divide our work into two main areas: virtual environments and robot-assisted manipulation systems. Our interest in virtual environments focuses on reality-based modeling, in which measurements of the static and dynamic properties of actual objects are taken in order to produce realistic virtual environments. Thus, we must develop methods for acquiring data from real objects and populating pre-defined models. We also seek to create systems that can provide active manipulation assistance to the operator through haptic, visual, and audio cues. These systems may be teleoperated systems, which allow human users to operate in environments that would normally be inaccessible due to hazards, distance, or scale. Alternatively, cooperative manipulation systems allow a user and a robot to share a tool, allowing the user to guide or override the robot directly if necessary. Haptics in human-machine systems can have many applications, such as undersea and space operations, training for pilots and surgeons, and manufacturing. We focus much of our work on medical applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권9호
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• pp.4144-4165
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• 2018

Software-defined networking (SDN) has emerged as a promising technology for network programmability and experiments. In this work, we focus on virtual network embedding in multiple controllers SDN network. In SDN virtualization environment, virtual SDN networks (vSDNs) operate on the shared substrate network and managed by their each controller, the placement and load of controllers affect vSDN embedding process. We consider controller placement, vSDN embedding, controller adjustment as a joint problem, together considering different quality of service (QoS) requirement for users, formulate the problem into mathematical models to minimize the average time delay of control paths, the load imbalance degree of controllers and embedding cost. We propose a heuristic method which places controllers and partitions control domains according to substrate SDN network, embeds different QoS constraint vSDN requests by corresponding algorithms, and migrates switches between control domains to realize load balance of controllers. The simulation results show that the proposed method can satisfy different QoS requirement of tenants, keep load balance between controllers, and work well in the acceptance ratio and revenue to cost ratio for vSDN embedding.

• 한국전자통신학회논문지
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• 제10권10호
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• pp.1101-1108
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• 2015

본 논문은 망 분리 가상 컴퓨터 환경 제공 방법 및 시스템을 제공한다. 본 가상 컴퓨터 환경 제공 방법은 가상 기능 수행을 위해 필요한 가상 자원 요청을 생성하는 단계 및 가상 자원 등록 요청을 네트워크 프로토콜 포맷으로 변환하여 네트워크를 통해 전송하는 단계를 포함한다. 이로 인해, 등록 처리 절차가 조합형 망 분리 가상 컴퓨팅 자원 할당과 임의 시간 동안 가상 컴퓨터를 사용하기 위해서, 서버와 클라이언트 또는 휴대폰 사이에서 가능해졌다. 언제든, 인터넷에 접속해 내 컴퓨터와 동일한 환경에서 업무를 처리 할 수 있게 된다.

• 한국멀티미디어학회논문지
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• 제12권1호
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• pp.130-138
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• 2009

컴퓨터와 함께 많은 시간을 보내는 현대인들 중에는 바탕화면과 화면보호기로 마음의 편안함을 주는 자연풍경이나 가상수족관 등을 설정하는 사용자들이 증가하고 있다. 가상수족관은 임의의 가상 해저환경에서 자유롭게 행동하는 여러 종류의 물고기를 만들고, 동작을 분석하여, 물고기들의 애니메이션 작업을 수행함으로써 만들어진다. 본 논문에서는 유체의 형태변화를 실시간으로 표현하는 유체 애니메이션 기법과 가상물고기의 다양한 속성에 따라 상호작용을 할 수 있는 Smart Fish기술을 이용하여 활용가치가 높은 실감형 가상수족관을 구축하는 방법을 제안했다. 본 논문에서 제안하는 방법은 다양한 해저환경을 표현하는 가상수족관, 수족관 화면 보호기, 물고기 육성 게임 등에 활용되어질 수 있다.

• 인터넷정보학회논문지
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• 제19권5호
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• pp.123-131
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• 2018

A virtual team consists of various members with a range of professional skills. An IT virtual team can confer such advantages as improving creativity and solving problems in e-business. However, virtual teams are less cohesive than off-line based teams, at least partly because they do not meet face-to-face to solve problems. If the cohesion of the members in a team is weak, overall performance can decrease. Therefore, this study seeks to understand the specific types of leadership needed to increase the cohesiveness of the members in a virtual team. Leadership is the most important factor for the successful operation of a virtual team. Leaders engage members with goals, and motivate them by creating positive relationships. This study describes the idealized influence of transformational leadership in which a leader directly engages members in a goal, and the role of participative goal setting in which members set their own goals. In addition, this research demonstrates the benefits of a positive attitude of a leader towards their team members and the influence of leader-member exchanges. If the cohesion of virtual teams is improved through specific leadership, the team members will be more committed to their teams and work, and the team's performance will improve. Furthermore, the successful operation of virtual teams will provide an opportunity for companies in e-business to gain a competitive advantage in the contemporary environment, where creativity is important.

• 대한기계학회논문집
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• 제1권3호
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• pp.125-130
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• 1977

This is a dimensionless analysis of interior ballistics for the design of gun tube. One of the characteristics of this analysis is to ues the .ETA.$_{j}$ number which means a relative quantity of virtual work to the kimetic energy of projectile at the muzzle. In order to apply the concept of virtual work, it is assumed that the projectile is moved from the beginning to the end of bore under constant pressure of the certain travel distance of projectile. The principle of the analysis is induced from the Le Duc equation, which expresses velocity as a function of projectile travel and is based on the translation of a hyperbolic curve. From this non-dimensional analysis, the optimum design parameters of pressure in the bore, velocity and acceleration of projectile can be obtained from the table of figure without computation. This method was verified by the experimental work.k.