• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.367-370
• /
• 2003

In this paper, an efficient modeling method of wind turbine system is proposed using multi-body dynamics. This method is based on representing a wind turbine system as a multi-body system with several rigid bodies. Also, simulation software WINSIM is developed to evaluate performance of wind turbine system. Simulation results show that proposed modeling method and simulation software is efficient and reliable

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.3
• /
• pp.150-156
• /
• 1998

In this paper, a 3-DOF(Degree Of Freedom) rigid body model is developed for dynamic analysis of a hydrostatic table. The dynamic coefficients, stiffness and damping constant of each pad are calculated from the mass flow continuity condition. The validity of this model is examined in theoretical and experimental method. The dynamic behavior when mass unbalances and local variations of stiffness and damping of pads present is analyzed for real applications of hydrostatic table. Since the theoretical and experimental results show goof agreement. it can be said that the 3-DOF rigid body model is useful for the dynamic model of the table. The analysis reveals that the pitching motion is the dominant mode of vibration, It also reveals that unbalanced loads can increase amplitude of tilting motion and reduce natural frequencies and damping capacity of the hydrostatic table.

• CDE review
• /
• v.18 no.2
• /
• pp.38-46
• /
• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.890-895
• /
• 2005

This paper presents the dynamic analysis of a cantilever beam undertaking impulsive force that undergoes rigid body motion. The transient response of the beam induced by the impulsive force and the rigid body motion is calculated based on hybrid deformation variable modeling method by applying the Rayleigh-Ritz assumed mode method. The stiffness variation effect caused by the rigid body motion is considered in this modeling. The effects of the impulsive force position and the angular velocity on the transient responses of the beam are investigated through numerical studies.

• Fibers and Polymers
• /
• v.6 no.4
• /
• pp.348-354
• /
• 2005

These days consumers' various demands are accelerating research on apparel manufacturing system including automatic measurement, pattern generation, and clothing simulation. Accordingly, methods of reconstructing human body from point-clouds measured using a three dimensional scanning device are required for apparel CAD system to support these functions. In particular, we present in this study a human body reconstruction method focused on two issues, which are the decision of the number of control point for each sectional curve with error bound and the local knot removal for reducing the unusual concentration of control points. The approximation of sectional curves with error bounds as an approximation criterion leads all sectional curves to their own particular shapes apart from the number of control points. In addition, the application of the local knot removal to construction of human body sectional curves reduces the unusual concentration of control points effectively. The results may be used to produce an apparel CAD system as an automatic pattern generation system and a clothing simulation system through the low level control of NUBS or NURBS.

• International Journal of Aeronautical and Space Sciences
• /
• v.9 no.1
• /
• pp.121-128
• /
• 2008

This paper describes the modeling and autopilot design procedure of a Blended Wing-Body(BWB) UAV. The BWB UAV is a tailless design that integrates the wing and the fuselage. This configuration shows some aerodynamic advantages of lower wetted area to volume ratio and lower interference drag as compared to conventional type UAV. Also, BWB UAV may be increase payload capacity and flight range. However, despite of these benefits, this type of UAV presents several problems related to flying qualities, stability, and control. In this paper, the detailed modeling procedure of BWB UAV and stability analysis results using the linearized model at trim condition are represented. Finally, we designed the autopilot of BWB UAV based on a simple control allocation scheme and evaluated its performance through nonlinear simulation.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.1
• /
• pp.88-98
• /
• 2014

A supercavitation is modern technology that can be used to reduce the frictional resistance of the underwater vehicle. In the process of reaching the supercavity condition which cavity envelops whole vehicle body, a vehicle passes through transition phase from fully-wetted to supercaviting operation. During this phase of flight, unsteady hydrodynamic forces and moments are created by partial cavity. In this paper, analytical and numerical investigations into the dynamics of supercavitating vehicle in transition phase are presented. The ventilated cavity model is used to lead rapid supercavity condition, when the cavitation number is relatively high. Immersion depth of fins and body, which is decided by the cavity profile, is calculated to determine hydrodynamical effects on the body. Additionally, the frictional drag reduction associated by the downstream flow is considered. Numerical simulation for depth tracking control is performed to verify modeling quality using PID controller. Depth command is transformed to attitude control using double loop control structure.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.8
• /
• pp.115-125
• /
• 2003

To analyze the applications of all types of mechanical systems, general purpose analysis programs have been developed and commercialized. However, it is customary to develop and use customized programs even though they sometimes require more work than a general purpose program. A customized program is simplified to adapt to a particular application from the beginning, is designed for small computers, and developed with hardware-in-the-loop in mind so it can be applied effectively. By adding design knowledge and bundling know-how to an analysis program, analysis time can be reduced. And because an analysis has to work in conjunction with other analysis programs, a proprietary program that the user can easily modify can be useful. In this thesis, a multi-body dynamics analysis system is presented using one of the most useful programming techniques, object-oriented concept. The object-oriented concept defines a problem from the physical world as an abstract object, an abstract model. The object becomes encapsulated with the data and method. Simulation is performed using the object's interface. It is then possible for the user and the developer to modify and upgrade the program without having particular knowledge of the analysis program. The method presented in this thesis has the following advantages. Since the mechanical components of the multi-body system converts independent modeling into a class, the modification, exchange, distribution, and reuse of elements are increased. It becomes easier to employ a new analysis method and interface with other S/W and H/W systems. To employ a new analysis method, there is no need to modify elements of the main solver and the Library. In addition, information can be communicated to each object through messaging. It makes the modeling of new elements easier using inheritance. When developing a S/W for the computer simulation of physical system, it is reasonable to use object-oriented modeling. Also, for multi-body dynamics analysis, it is possible to develop a solver that is user-oriented.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.7 no.2
• /
• pp.76-81
• /
• 2007

Threshold voltage ($V_{th}$) modeling of doublegate (DG) MOSFETs was performed, for the first time, by considering barrier lowering in the short channel devices. As the gate length of DG MOSFETs scales down, the overlapped charge-sharing length ($x_h$) in the channel which is related to the barrier lowering becomes very important. A fitting parameter ${\delta}_w$ was introduced semi-empirically with the fin body width and body doping concentration for higher accuracy. The $V_{th}$ model predicted well the $V_{th}$ behavior with fin body thickness, body doping concentration, and gate length. Our compact model makes an accurate $V_{th}$ prediction of DG devices with the gate length up to 20-nm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.38 no.6
• /
• pp.725-731
• /
• 2020

In mineral resource development, resource exploration is a task to find economical minerals on the surface and underground, and the success rate is low compared to the development and production stages, and it is necessary to collect a lot of data through exploration and accurately analyze the collected information. In this study, mine spatial information was constructed using a 3D (Three-dimensional) laser scanner, and accuracy evaluation was performed to obtain a maximum deviation of 0.140 m and an average of 0.095 m in the X, Y and Z directions, and the possibility of utilizing the construction of mine geospatial information through a 3D laser scanner could be presented. In addition, the ore body modeling was performed by applying the interpolation method of the ore body section using the resource exploration results. The ore body modeling result was superimposed with the modeling result of the mine geospatial information built through the 3D laser scanner to construct the ore body modeling result based on the precise mine geospatial information. The results of ore body modeling based on mine geospatial information built through research can increase the ease of data interpretation and the accuracy of the calculated data, which will greatly increase the efficiency of work related to mineral resource development and mine damage prevention in the future.