• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1297-1301
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• 1997

Generally, singularity analysis of 6-DOF parallerl manipulators is very difficult and, as result, velocity relation has many uncertainties. In this paper, an alternative method using the local structurizatioin method(LSM) for the analysis of singular configuraions is presented. With LSM, the velocity relation can be represented in a simple form, and the result is totally equivalent to the conventional velocity relation. The velocity relation suggested in this paper gives a closed-form solution of singularities.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1013-1016
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• 1995

This paper deals with dynamics and control of a PRP6-DOF parallel manipulator. Dynamic modeling includes the effect of inertia of all links in the mechanism to increase modeling accuracy. Kinematic analysis about forward and inverse kinematics is also explained. Using Lagrange-D' Alambert method we get equations of motions in a link space which fully represent 6DOF motions of the manipulator.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.217-220
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• 1996

In this paper, a fully geometrical method for the determination of the workspace of a 6-DOF parallel manipulator is presented using the concept of 4-bar linkage. The reachable and dexterous can be determined from the proposed algorithm. In order to evaluate the workspace, each leg is considered as an open chain, and two kinematic constraints are developed. The proposed method is verified by simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.8
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• pp.619-626
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• 2017

In this work, the effect of attitude angle variation on drag coefficients of hemisphere in a Mach 6 flow has been investigated. Experiments were conducted in a shock tunnel and a free-falling technique was used to minimize flow disturbance by a sting. For attitude and drag coefficient measurements of a free-falling hemisphere, a free-falling technique based on a releasing mechanism with a stair-typed module and an electromagnet was developed. A shadowgraph technique was used for flow visualization using a high-speed camera.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.977-985
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• 2011

Airborne separation assurance is a key requirement for Free Flight Airspace operations, This paper study the feasibility of airborne separation assurance for free flight Airspaces operations by evaluating the efficiency measurement models. Three qualitatively different methods are utilized; one based Ground and Air conflict probability model, other based Dynamic Density model. the other based Direct operating cost model. The evaluation is Direct Operating Cost model and Two metrics are utilized for the efficiency measurements; airborne separation assurance performed quite well in the Free Flight evaluation; (1) 2 scenario of the conflict situations are resolved; (2) The MD-80 flight peformed separation assurance and efficiency, Not only appling for geometric method algorithm is more efficiently than potential method, but also the most efficiently geometric combined method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1607-1613
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• 2008

We investigated the miniaturized free electron laser(FEL) module based on microcolumn. The miniaturized FEL is composed of two parts: electron generation part and radiation emission part. The radiation emission part, called wiggler, consists of a grid plate. While the electrons are passing through the wiggler, electron trajectory shows sinusoidal curve caused by the periodically applied voltage on the grid, and then it give rise to radiation emission. We analyzed the wiggler parameters, grid width, depth, period, applied voltage and the pair wiggler space using 2-D simulation tool.

• Journal of the Korean Geographical Society
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• v.40 no.6 s.111
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• pp.671-693
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• 2005

This paper is to explore critically environmentalism, especially in terms of environmental justice, suggested or implied in theory of liberalism which has been the ideological foundation of contemporary society. It begins with a brief look at liberal perspective in a broad sense, then interprets in-depth the classical liberalism of J. Locke, libertarianism (esp. R. Nozick) and utilitarianism (including cost-benefit analysis) from the environmental point of view. And finally it considers liberal pluralism and other alternative theories of pluralism, especially communitarianism (esp M. Walzer), postmodern pluralism (esp. I. Young), and cultural pluralism (esp. C. Taylor) in order to overcome limitations of liberal environmentalism and to find out some clues for theory of environmental justice. In conclusion, this paper argues that we need to transfer from liberalism (including liberal pluralism) to critical pluralism in oder to develop a proper understanding of environmental problems and to conceptualize a desirable theory of environmental justice.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.19-29
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• 2006

In this study, numerical simulation of airframes separating from a missile system has been preformed. For the time-accurate trajectory simulation, six D.O.F equations of motion of multiply connected bodies were derived and these equations have been coupled with the unstructured overset mesh technique for the treatment of independent mesh blocks moving with each body component. Applications were made for the simulation of the airframe separation at missile angles of attack of 0 and 5 degrees. It was demonstrated that the present method is efficient and robust for the prediction of unsteady time-accurate flow fields involving multiple bodies in relative motion.

• Journal of Korea Game Society
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• v.10 no.6
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• pp.57-65
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• 2010

In this paper, mobility performance indices are proposed which may be used to estimate characteristics of output velocity space in six-degree-of-freedom parallel mechanism. In order for manipulability and condition number to not suffer from lack of the physical meaning due to dimensional inhomogeneity, output space is partitioned into translational velocity space and rotational velocity space, respectively. In each space, mobility ellipsoids corresponding to unit input space are defined and two types of mobility performance in translational velocity spaces indices are derived. Two types of mobility performance in rotational velocity spaces indices are derived.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.45-56
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• 1999

This paper presents a method for designing an autopilot of the BTT missile using 2DOF Wiener-Hopf control technique to improve tracking performance. Linear controllers are designed based on the linearized models which are obtained from the nonlinear missile dynamic equations at various operating points. The gain scheduling technique is used to implement the final autopilot. A simulation on the flight of missiles is carried out through the use of 6DOF equation program including exact nonlinear equations of the missile and the variations of aerodynamic variables in order to check applicability of the suggested method in real situation.