• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.939-943
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• 2004

The side and rear-side collision warning system using fuzzy control algorithms is discussed in this paper. Common rearside warning system has many problems. For example if target vehicle comes into the warning area, it must unconditionally warn. Drivers could be interrupted by it. To solve the problem, I divided measuring area into two sections. One section is blind area of vehicle and the other rear-side area. For blind area, obtained data was filtered inefficient warning signal by using relative velocity method. For rear-side area, a fuzzy logic algorithm is used to recognition of obstacles. According to our experiment relative velocity method and fuzzy logic algorithms were very efficient.

• 한국공작기계학회논문집
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• 제15권5호
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• pp.44-50
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• 2006

Cam mechanisms are one of the most popular devices for generating irregular motion and are widely used in many automatic equipments, such as textile machinery, internal combustion engines and other automatic devices. In order to obtain the positive motion of follower by rotating cam, its shape should be correctly designed and manufactured. In present paper, a CAD/CAM system is developed for shape design of disk cams using relative velocity method and NC code generation using the biarc curve interpolation. And, a disk cam is successfully manufactured by the developed CAD/CAM system. Thus, it is shown that the developed CAD/CAM system can be used for high precision cam profile CNC grinding machine.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.103-108
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• 2007

This paper presents a friction model to realize self-excited vibration of multi-body systems. The friction coefficient is modeled with a spline function in most commercial codes. Even if such a function resolves the problem of discontinuity in friction force, it cannot realize self-excited vibration phenomena. Furthermore, as the relative velocity approaches zero, the friction coefficient approaches zero with the conventional model. So, slip occurs when small force is applied to the system. To avoid these problems a new friction model is proposed in this study. With the new friction model, the self-excited vibration can be realized since the friction coefficient changes with the relative velocity. Furthermore, the slip phenomena could be reduced significantly with the proposed model.

• 한국연소학회지
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• 제1권1호
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• pp.57-64
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• 1996

The atomizing characteristics in a spray injected from a twin fluid atomization nozzle have been investigated. The Sauter mean diameters as mean diameter are compared with wavelength calculated from the instability theory. The Sauter mean diameter are measured by the Fraunhofer diffraction theory using the Malvern particle sizer. The wavelength is calculated using the mean relative velocity instead of the exit relative velocity of nozzle. Also shadowgraphy technique is used to visualize atomization phenomena. This paper gives a possibility that the mean diameter can be predicted with the wavelength obtained by the simple instability theory.

• 설비공학논문집
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• 제10권1호
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• pp.88-94
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• 1998

The thermal performance of cooling towers is affected mainly by the velocity, temperature and humidity of the entering air, In this paper, the effects of these variables are experimentally investigated for both counter-flow and cross-flow cooling towers. The cooling performance is reduced by up to 50% as the relative humidity of the entering air is increased from 40% to 80%. The higher air velocity and lower coolant flow show better cooling performance. The coolant loss rates in the present experimental conditions are in the range of 0.4 to 1.7%

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.60-63
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• 2000

In this study, efficient force reflection algorithm is developed for the Haptic Display by using a proxy concept and friction model. When there are not any contacted obstacles the proxy is following human operator's command trajectory in the 3D virtual space. But when the operator's command trajectory is locating inside of the object, the proxy is constrained by the surface of the object. Here only with the information of the proxy position and operator's command trajectory at every time step, we can calculate the reflection force and its orientation. To display the friction force between two virtual stiff material which are sliding against each other, modified Karnopp's friction model is used. In the friction model, a damping term and a Stribeck effect term are included to display the relative velocity effect and stick-slip effect at the very low relative velocity region respectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.158.2-158
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• 2001

This paper introduces the design and implementation of a signal processing system for an airborne active homing radar system. This airborne active homing radar system uses the pulse Doppler radar of high PRF (Pulse Repetition Frequency) for computation of exact relative velocity of the target. This system carries out two operations mainly. The first is to transmit and receive microwave signal through the antenna. The second is to calculate the relative velocity of the target taking advantage of the Doppler frequency signal reflected from the target and detect the angle error between a target and an antenna LOS (Line Of Sight) to make the antenna direction coincident with the target. The signal processing system has a role of the latter.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 추계학술대회 논문집
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• pp.52-56
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• 1992

A kinematically admissible velocity field for closed-die forging of spur gear is proposed. The velocity field is divided into three regions of deformation. In the analysis, the involute curve is approximated to be straight line and the upper-bound method is used to calculate energy dissipation rate. A constant frictional factor has been assumed on the contacting surfaces. The effects of root diameter relative pressure is independent of root diameter for the same number of teeth, but increases with the number of teeth on a given root diameter. In the presence of friction, relative forging pressure increases with increasing root diameter at the start of forging, but decreases with increasing root diameter in the processing of forging.

• 한국정밀공학회지
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• 제24권2호
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• pp.73-85
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• 2007

The rear lateral collision warning system using fuzzy control algorithms is discussed in this paper. Common rear lateral warning system has many problems. For example if target vehicle comes into the warning area, it must unconditionally warn. Drivers could be interrupted by it. To solve the problem, I divided measuring area into two sections. One section is blind area of vehicle and the other rear lateral area. For blind area, obtained data was filtered inefficient warning signal by using relative velocity method. For rear lateral area, a fuzzy logic algorithm is used to recognition of obstacles. According to our experiment relative velocity method and fuzzy logic algorithms were very efficient.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.235-242
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• 2003

The solids and the fluids in porous media have a relative velocity to each other. Due to physically and chemically different material properties and their relative velocity, the behavior of saturated porous media is extremely complicated. Thus, in order to describe and clarify the deformation behavior of saturated porous media, constitutive models for deformation of porous media coupling several effects such as flow of the fluids or thermodynanical change need to be developed in frame of Arbitrary Lagrangian Eulerian (ALE) description. The aim of ALE formulations is to maximize the advantages of Lagrangian and Eulerian elements, and to minimize the disadvantages. Therefore, this method is appropriate for the analysis of porous media that are considered for the behavior of the solids and the fluids. In this work, governing equations of porous media based on ALE description are obtained from governing equations in frame of updated Lagrangian description. Then, weak forms of these equations are derived using arbitrary weighting functions.