• 대한전기학회논문지:시스템및제어부문D
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• 제53권5호
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• pp.309-314
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• 2004

In the established virtual-reality system, although it is possible to transact a faculty of sensation and graphic in a single PC, virtual object forcibly treated with rigid body for the reason of the huge amount of calculation, and the number of polygon is restricted. Furthermore, there is some difficulty in the financial aspect and a program field, because the existing virtual-reality system needs at least two workstations or super computers. In this study, the new force-reflecting algorithm called as "Proxy" and a finite element method of Hyperion are applied to this system in order to transact in real-time. Consequently, though the number of polygon, which brings about an obstacle is increased in the real-time graphic transaction, this system makes it possible to transact in the real-time, not being influenced by the size of the virtual object.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.220-226
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• 1996

This paper describes the force display system which presents feel information to the operator through manipulating a virtual tool with a master arm in the simulated environment. The movement of a tool grasped by the operator, which is modeled as a circle or a square is displayed in the graphic screen of a computer. When the tool contacts with the virtual environment, the operator is forced to feel contact and the feature of the virtual environment through torque control of the master arm. Contact situations are modeled as close as to the reality considering the friction, and multiple contacts. Several experients are conducted and the effectiveness of the developed system is confirmed.

• 한국지능시스템학회논문지
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• 제15권4호
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• pp.498-504
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• 2005

본 논문에서는 퍼지 로직을 이용한 수중 로봇의 충돌 회피를 제안하였다. VFF(Virtual Force Field) 방법은 이동 로봇 분야에서 널리 사용하고 있는 충돌 회피 알고리즘이다. 본 논문에서는 이를 수중 로봇의 자율 항해를 위한 형태로 변형시킨 Modified Virtual Force Field(MVFF)를 제시하였다. 보다 정교한 알고리즘을 위해서 퍼지 로직을 이용한 MVFF를 구성하였고, 이를 수중 로봇의 경로 유지와 충돌 회피에 적용하였다 퍼지 로직은 수중 로봇의 자율 항해 동안 직면하게 되는 다양한 상황들을 다루었다. 제안한 충돌 회피 알고리즘은 다수개의 고정 장애물에 대해서 좋은 성능을 제시하였다. 시뮬레이션 결과를 통해 제안된 방법이 수중 로봇의 충돌 회피에 효과적으로 적용될 수 있음을 보였다.

• 산업경영시스템학회지
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• 제37권4호
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• pp.212-217
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• 2014

Recently, Korea Air Force has been facing a lot of problems in its pilot training system such as training time shortage due to the expensive gas price, noise pollution and difficulties in finding airspace for training. To tackle these problems, a new training system (called L-V training system) using both aircraft and its simulator has been suggested. In the system, a data link is established between aircraft and simulator to exchange their flight information. Using the flight information of simulator, aircraft can perform various air missions with or against imaginary aircraft (i.e., simulator). For this system, it is crucially important that fair fighting condition has to be guaranteed between aircraft and simulator. In this paper, we suggested an approach to impose a maneuvering restriction to simulator in order to provide fair fighting condition between aircraft and simulator.

• 로봇학회논문지
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• 제8권3호
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• pp.186-196
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• 2013

Since its introduction (e.g., [4, 6]), virtual coupling technique has been de facto way to connect a haptic device with a virtual proxy for haptic rendering and control. However, because of the single dependence on spring-damper feedback action, this virtual coupling suffers from the degraded transparency particularly during contact tasks when large device/proxy-forces are involved. In this paper, we propose a novel virtual coupling technique, which, by utilizing passive decomposition, reduces device-proxy position deviation even during the contact tasks while also scaling down (or up) the apparent inertia of the coordinated device-proxy. By doing so, we can significantly improve transparency between multiple degree of freedom (possibly nonlinear) haptic device and virtual proxy. In other to use passive decomposition, disturbance observer of [3] is adopted to estimate human force with some dead-zone modification to avoid "winding-up" force estimation in the presence of device torque saturation. Some preliminary experimental results are also given to illustrate efficacy of the proposed technique.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.51.4-51
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• 2002

$\textbullet$ A noval haptic mouse system is developed for human computer interface. $\textbullet$ Five bar mechanism is adapted for 2 dof force feedback with virtual environment. $\textbullet$ Double prismatic joint type mechanism is adapted to reflect 1 dof grabbing force feedback. $\textbullet$ Cable driven mechansim is used for actuation to reduce backlash and endow backdrivability. $\textbullet$ Virtual wall perception experiment is conducted to obtain force specification for haptic mouse. $\textbullet$ Average mouse workspace is measured using magnetic position tracker.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권4호
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• pp.137-145
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• 2001

The magnetic force calculation methods, the Maxwell＇s stress tensor method, virtual work method, and nodal force method, are reviewed and the equivalence of them are theoretically proved. The methods are applied to the magnetic force calculation of 2D linear and nonlinear problems, and 3D nonlinear problem. As the results, the convergence of the methods as the number of elements increases, accuracy of the methods, and integral path dependence of the methods are discussed. Finally some recommendations on the usage of the methods, including the determination of the integral path, are given.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1513-1518
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• 1996

A force reflecting hand controller can be used to provide more realistic information to the operator of a teleoperation system such as kinesthetic feedback from a slave robot. In this paper, a new design concept of a force reflecting 6-DOF hand controller utilizing the kinematic structure of a Stewart Platform is presented. Based on the optimal design technique of a Stewart Platform, a force reflecting hand controller has been designed and constructed to verify the technical feasibility of proposed design concept. In order to provide an operator with kinesthetic feedback information, a force mapping algorithm based on a reciprocal product of screws has been introduced. Finally, the technical feasibility of the design concept has been demonstrated through some of experimental results of the device under virtual environment on a real-time graphic system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.2892-2913
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• 2016

Network virtualization promises to play a dominant role in shaping the future Internet by overcoming the Internet ossification problem. However, due to the injecting of additional virtualization layers into the network architecture, several new security risks are introduced by the network virtualization. Although traditional protection mechanisms can help in virtualized environment, they are not guaranteed to be successful and may incur high security overheads. By performing the virtual network (VN) embedding in a security-aware way, the risks exposed to both the virtual and substrate networks can be minimized, and the additional techniques adopted to enhance the security of the networks can be reduced. Unfortunately, existing embedding algorithms largely ignore the widespread security risks, making their applicability in a realistic environment rather doubtful. In this paper, we attempt to address the security risks by integrating the security factors into the VN embedding. We first abstract the security requirements and the protection mechanisms as numerical concept of security demands and security levels, and the corresponding security constraints are introduced into the VN embedding. Based on the abstraction, we develop three security-risky modes to model various levels of risky conditions in the virtualized environment, aiming at enabling a more flexible VN embedding. Then, we present a mixed integer linear programming formulation for the VN embedding problem in different security-risky modes. Moreover, we design three heuristic embedding algorithms to solve this problem, which are all based on the same proposed node-ranking approach to quantify the embedding potential of each substrate node and adopt the k-shortest path algorithm to map virtual links. Simulation results demonstrate the effectiveness and efficiency of our algorithms.

• 한국멀티미디어학회논문지
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• 제5권6호
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• pp.646-654
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• 2002

인간의 촉각감지 기능은 주위환경에 대한 중요한 정보를 제공하여 준다. 촉각 정보는 우리의 신체와 외부세계와의 접촉에 따른 위치 정보와 물체를 인지하고 조작하기 위한 감각적 정보 뿐 아니라 위험 여부까지 판단할 수 있는 정보를 제공해 준다. 그러나 촉각은 시각과 청각에 비해 상대적으로 덜 중요한 감각으로 인식되어져 왔으나, 가상현실과 컴퓨터 게임에 있어서는 중요한 역할을 수행할 수 있다. 촉각을 통해 플레이어가 가상 세계의 물체에게 직접 영향을 줄 수도 있고 받을 수도 있는 적극적인 인간 감각이기 때문이다. 본 논문에서는 인간의 촉각의 특성을 조사하고 이를 응용하기 위한 힘 감지 센서를 사용한 연구방법을 제시한다. 또한 실제적인 게임적용을 위하여 간단한 힘 모델링과 구조체 형식을 제안한다. 그 결과 센서 출력을 분석하여 힘의 분포, 크기, 중심을 구하고 이 정보를 응용하여 특정부위에 대한 작용, 반작용을 구현 할 수 있다. 본 결과는 컴퓨터 게임과 가상현실에서 촉각 감지와 응용을 위한 기본 자료로 활용될 수 있다.