• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1737-1743
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• 2013

This paper proposes the range and velocity of the object estimation method using a moving camera. Structure and motion (SaM) estimation is to estimate the Euclidean geometry of the object as well as the relative motion between the camera and object. Unlike the previous works, the proposed estimation method can relax the camera and object motion constraints. To this end, we arrange the dynamics of moving camera-moving object relative motion model in an appropriate form such that the nonlinear observer can be employed for the SaM estimation. Through both simulations and experiments we have confirmed the validity of the proposed estimation algorithm.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.478-481
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• 2009

As a first step for aerodynamic analysis of vertical axis wind turbine, dynamic stall characteristics of airfoil was investigated. Dynamic stall of wind turbine airfoil is caused by severe variation of angle of attack and relative velocity of flow around airfoil. Angle of attack and relative velocity can be expressed with tip speed ratio. Variation of angle of attack is strongly dependent on the tip speed ratio. For tip speed ratio, 1.4 and free stream velocity, 15m/s, dynamic stall characteristics of wind turbine airfoil is compared with those of oscillating airfoil having same angle of attack variation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.920-924
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• 2002

This paper presents the reverse design of a cam mechanism using NURBS(Nonuniform Rational B-spline curve). Cam is very difficult to make the accurate shape on the design and the manufacture. Because the cam shape is commonly made in order to move in special functions. The reverse design can be used to check accuracy between the designed data and the manufactured data of the cam shape and also reproduce the cam without the design data. The reverse design procedures consist of motion analysis and curve fitting. The motion analysis is used the central difference method and the relative velocity method to find the displacement and velocity. The curve fitting is used NURBS to develope the whole curve. The central difference method is derived in the 3 dimensional space.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.109-118
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• 2005

A functional suspension model is proposed as a kinematic describing function of the suspension that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center and steering rack displacement. The relative velocity and acceleration of the wheel is represented in terms of first and second derivatives of the kinematic describing function. The system equations of motion for the full vehicle dynamic model are systematically derived by using velocity transformation method of multi-body dynamics. The comparison of field test results and simulation results of the ADAMS/Car demonstrates the validity of the proposed functional suspension modeling method. This model is suitable for real-time vehicle dynamics analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.185-191
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• 2001

In many papers, the powertrain system generally has been madeled as one-dimensional torque model. One-dimensional powertrain model may calculate the torque correctly but it does not consider the non-rotational degrees-of-freedom of the powertrain components and the interaction of these degrees-of-freedom with the vehicle body frame and suspension. To consider the non-rotational degrees of freedom, the differential is modeled as a three-dimensional rigid body in this paper. A constant velocity joint is newly formulated and a relative constraint is also formulated to model the motion transfer due to gear ratio of the differential. Implementing the proposed powertrain system in the multibody model, more detail dynamic responses can be obtained. Obtained outputs such as reaction torques on the constant velocity joint and reaction forces on the rack can be useful data in the design of a powertrain.

• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.45-51
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• 2005

The solar shading height for the cultivation of plants is a very important factor because it has an effect on the variations of the solar energy. In this study, the solar shadings were built in Daegu region to investigate the optimum thermal conditions for the cultivation of plants and to provide the basic data. The thermal environment factors (dry bulb temperature, relative humidity, air velocity) were then measured and analyzed. It is found that the heights of the solar shadings have an uniform effect on the thermal environment for the cultivation of plants: the higher the heights of the solar shadings the higher temperature was obtained. But surprisingly this trend was not found for the relative humidity and the air velocity.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.1
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• pp.65-70
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• 2001

During the summer season, it is very hot and humid in Korea. So the humidity is an important factor regarding the environmental control function of building envelops. The purpose of this research is to measure and analyze the characteristics of such environmental factors as relative humidity, dry bulb temperature and air velocity varies both in the clay and cement envelop structures using granite dome models during the summer time. The interior relative humidity of the clay model is constant regardless of exterior humidity although a little range of variation is shown in comparison to the cement model.

• Particle and aerosol research
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• v.14 no.2
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• pp.35-40
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• 2018

Vertical particle size distribution, total particle concentration, wind velocity, temperature and humidity measurement was performed with a drone. The drone was equipped with a wind sensor, house-made optical particle count(Hy-OPC), condensation particle counter(Hy-CPC), GPS, Temperature, Relative Humidity, Pressure and communication system. Base on the wind velocity and the particle size vertical distribution measurement with drone, the particle mass flux was calculated. The vertical particle distribution showed that the particle number concentration was very strongly correlated with the relative humidity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.898-902
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• 1999

During summer season, the weather condition of Korea is hot and humid. So humidity elements are very important relating to building envelope condition. The purpose of this investigation is to measure and analyze characteristics of summer's environmental elements such as relative humidity, dry bulb temperature and air velocity in the clay/cement envelope materials using a granite dome model. According to the variation of exterior humidity, the state of interior relative humidity for clay model has an equal tendency, although a little range of variation is shown in comparison to the cement model.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.26-37
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• 1994

A kinematically admissible velocity field for the numerical analysis of closed-die forging process 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 frictional factor has been assumed on the contacting surfaces. The effects of root diameter, number of teeth, and friction factor are determined on the relative forging pressure. The frictionless 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, the relative forging presure increasing root diameter at the start of forging, but decreases with increasing root diameter in the processing of forging.