• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.767-772
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• 2002

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential in the seismic design to perform the accurate site-specific ground response analysis. In this paper, one-dimensional seismic characteristics of waste landfill are studied based on the vertical propagation of horizontal shear waves through the column of soil/waste. Seismic response analysis is peformed for short-period, long-period and artificial earthquake ground motions using a computer program for seismic response analysis of horizontally layered soil deposits. The computed peak ground accelerations are compared with the values calculated according to Korean seismic design guidelines. The analysis result shows that the long-period earthquake causes the largest peak ground acceleration while the artificial earthquake results in the smallest one.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.742-748
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• 2000

This paper presents a numerical method to analyze the electromechanical-coupled field in the spindle motor of a computer hard drive and investigates dynamic response due to the electromechanical excitation, i.e. unbalanced magnetic force and centrifugal force for the rotational asymmetric motor. Magnetic field is calculated from Maxwells equation and voltage equation by introducing nonlinear time-dependent finite element analysis. Mechanical motion of rotor is calculated by solving Newton-Euler equation. Electromechanical excitation and dynamic response are characterized by analyzing the free response of a rotating rotor and Fourier analysis of the excitation force and resulting vibration of a rotor. It shows that centrifugal force produces the unbalanced magnetic force even in the rotational symmetric motor. It also shows that resonance produces quite considerable vibration even when the high excitation frequency with small amplitude matches with the natural frequency of the spindle motor.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06a
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• pp.43-48
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• 1999

To clarify the motion characteristics of free-style Okinawan dance“Kachaasi”, first the subjective impression was quantitatively evaluated with semantic differential technique to cluster its types. Then, the contingency of joint rotation in shoulder, elbow and wrist joints was examined with multivariate autoregressive model. The time-series data of positions and angels of three joints were calculated according to the deforming conditions and shielding directions of the ring lights. As the results, in an excellent dancer, the motions of shoulder and elbow were highly synchronized and smoothly controlled. The low-frequency output of the shoulder and elbow were mutually interacted. Meanwhile, the wrist behaved independently of other joints' rotation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.686-691
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• 2008

This paper proposes the concept of "virtual sensor data" and its application for real time obstacle avoidance. The virtual sensor data is virtual distance which takes care of the movement of the obstacle as well as that of the robot. In practical application, the virtual sensor data is calculated from the odometry data and the range sensor data. The virtual sensor data can be used in all the methods which use distance data for collision avoidance. Since the virtual sensor data considers the movement of the robot and the obstacle, the methods utilizing the virtual sensor data results in more smooth and safer collision-free motion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.80-83
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• 2002

In this study, a single phase driven piezoelectric motor design is presented for linear motion-metal/ ceramics composite structure. Using ANSYS finite element analysis software, mode shape of free motor was obtained to clarify the working principle of this motor. And characteristics of the motor was measured. The motor is composed of a piezoelectric ceramic, a metal ring which has 4 arms, and a guider. The motor with 25.0[mm] diameter was studied by finite element analysis and experimentation too. As a result, the motor was expressed the best speed in resonance frequency. And according as voltage of the motor increase, the speed increased by ratio.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.393-396
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• 1998

To examine the influence of unsteady wake on the flow and heat transfer characteristics, an experiment has been conducted in a four-vane linear cascade. Flow and heat transfer measurements are made for the inlet Reynolds number of 66000(based on chord length and free-stream velocity). Turbulent intensity and stress were measured using hot wire anemometer, and to measure the convective heat transfer coefficients on the blade surfaces liquid crystal/gold film Intrex technique was used. The disturbance by the unsteady wake is characterized by the unresolved unsteadiness. The unsteady wake enhances the turbulent motion of flow in the cascade passage. It also promotes the boundary layer development and transition. The results show that heat transfer coefficients on the suction surface increase with increasing unresolved unsteadiness.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.120-122
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• 2004

Wearable input device that can make free-space typewriting possible is introduced. We named this device as $SCURRY^{TM}$. To measure the angular velocity of hand and the acceleration rates at the ends of fingers, we buried MEMS inertial sensors in this keyboard. We processed sensor signals to get the information on hand movement and finger-click motion. With this signal processing, apparent finger movements were depicted over the virtual keyboard shown on output device of a target computing system. In this paper, a finger-click recognition method is proposed to improve the recognition performance for finger clicking of $SCURRY^{TM}$. The proposed method is composed of three parts including feature extraction part, valid click part, and cross-talk avoidance part. The experiments were conducted to verify the effectiveness and efficiency of the proposed algorithms.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.97-104
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• 2003

This paper proposes a new parallel manipulator fur plane motion, and then discusses on the workspace and kinematical characteristics of the manipulator. The conventional planar parallel manipulators have some disadvantages which are complex non-closed type direct kinematics, workspaces containing useless voids, and concave type border tines of workspaces. The proposed planar parallel manipulator overcomes the above disadvantages, that is, the manipulator has simple closed type direct kinematics, a void-free workspace, and a convex type borderline of a workspace. This paper shows the simulation result of the workspace as well as performances indices using a homogeneous inverse Jacobian.

• Journal of the Korean Arthroscopy Society
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• v.13 no.3
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• pp.189-192
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• 2009

Although the articular cartilage is only a few milimiters thick, it has surprising stiffness to compression, exceptional ability to distribute load minimizing peak stress on subchondral bone and great durability. In many instances, it help to preserve normal joint function for more than 80 years. Varying in thickness, cell density, matrix composition, mechanical properties even within the same joint, it provides low-friction and pain free-motion. However, it lacks a blood or lymphatic supply and neurological elements are absent. It shows limited healing potential because of poor regenerative capacity.

• Advances in nano research
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• v.5 no.2
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• pp.113-126
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• 2017

This paper proposes a new nonlocal higher-order hyperbolic shear deformation beam theory (HSBT) for the static bending and vibration of nanoscale-beams. Eringen's nonlocal elasticity theory is incorporated, in order to capture small size effects. In the present model, the transverse shear stresses account for a hyperbolic distribution and satisfy the free-traction boundary conditions on the upper and bottom surfaces of the nanobeams without using shear correction factor. Employing Hamilton's principle, the nonlocal equations of motion are derived. The governing equations are solved analytically for the edges of the beam are simply supported, and the obtained results are compared, as possible, with the available solutions found in the literature. Furthermore, the influences of nonlocal coefficient, slenderness ratio on the static bending and dynamic responses of the nanobeam are examined.