• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1499-1512
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• 2000

The dynamic explicit finite element method and the static implicit finite element method are applied effectively to analyze total auto-body panel stamping processes, which include the forming stage , the trimming stage and the spring-back stage.\The explicit time integration method has better merits in the forming stage including highly complicated three-dimensional contact conditions. On the contrary, the implicit time integration method is better for analyzing spring-back since the complicated contact conditions are removed and the computing time to get the final static state is short. In this work, brief descriptions of the formulation and the factor study are presented. Further, the simulated results for the total auto-body panel stamping processes are shown and discussed. The formability and the weld line movement in stamping with Tailor Welded Blanks were investigated through QTR-OTR-FRT.

• Economic and Environmental Geology
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• v.23 no.1
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• pp.81-86
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• 1990

Palemagnetic study on the Deadong Super Group in the Mungyong area has been carried out to obtain the direction of NRM and virtual geomagnetic pole(VGP), and to investigate geomagnetic stratigraphy and geotectonic evolution. Twenty eight core specimens from five sites in Dangog and Bongmyongsan Formations yield magnetically stable results by thermal demagnetization test. Mean declination and inclination of Dangog and Bongmyongsan formations are $52.4^{\circ}E$ and $-57.3^{\circ}$, respectively, which indicate reversal polarity. VGP is located at $1.2^{\circ}N$ in latitude and $269.4^{\circ}E$ in longitude, which is quite different from those of other contemporary formations in China. This suggests that the study area has suffered from differnt tectonic movement caused by Daebo Orogeny occurred in the Korean Peninsula during post-Daedong and pre-Kyongsang Systems. As compared VGP of Daedong Super Group in the Mungyong area with wordwide Mesozoic paleomagnetic polarity stratigraphy, it is correlated with the reverse Epoch in the Graham normal interval. This suggests that the time of formations of Dangog and Bongmyongsan is in the age of 190-195 my.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.16-23
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• 2009

Driving simulators are useful tools not only to test the components of future cars but also to evaluate the telematics service and HMI (Human-Machine Interface). However driving simulators cannot be implemented to test and evaluate the telematics service system because the GPS (Global Positioning System) which contains basic functional support for the telematics module do not work in the VR (virtual reality) environment. This paper presents a method to implement telematics service to a driving simulator by developing the GPS simulator which is able to emulate GPS satellite signals consist of NMEA-0183 protocol and RS232C communication standards. It is expected that the driving simulator with the GPS simulator can be used to study HMI and human-factor evaluations of the commercial telematics system to realize the HiLES (Human-in-the-Loop Evaluation System).

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.283-290
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• 2007

A bi-modal tram has been developed to offer an advanced transportation service compared with existing vehicles. The All-Wheel-Steering system is applied to the bi-modal tram to satisfy the required steering performance because the bi-modal tram has extended length and articulated mechanism. An ECU for the steering system is essential to steer wheels on 2nd and 3rd axles by the specific AWS algorithm with the prescribed driving condition. The Hardware-In-the-Loop Simulation(HILS) system is planned for the purpose of evaluating the steering system of the bi-modal tram. There are kinematic links with the hydraulic actuator to steer wheels on each 2nd and 3rd axles and also same steering mechanism as the actual vehicle is in the HILS system. Controlling the movement of hydraulic actuator which reflects the lateral steering reaction force on each wheel is the key to realize the HILS system, but the reaction force is continuously changed according to various driving conditions. Therefore, the simulation through the multi-body dynamics model is used to obtain the required forces.

• Fashion & Textile Research Journal
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• v.11 no.2
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• pp.308-314
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• 2009

In creating an avatar, consumers can find out for themselves their own sizes to be entered. Also, putting in a face creation main-page menu option enables clients to make up their faces and match them to their bodies. Through this process when purchasing clothes through the internet consumers can enter their own body sizes and create avatars that are identical to their body shape. The uniqueness of developed prototype is that it creates an avatar similar to one's body shape according to body size inputs and demonstrates visually to customers the on-line comfort test which was only available off-line traditionally. The avatar follows the movement of mouse from left to right which enables 3 dimensional visualization. Through maximizing the visual effect this research focuses on enabling consumers to feel subjective parts as if they are off-line. This study seeks to provide a type of prototype of an online shopping mall that meets the demand of the consumers using the 3D avatar.

• Journal of Mechanical Science and Technology
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• v.18 no.1
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• pp.132-144
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• 2004

This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the velocity of the robots. To implement the concept to avoid collision among multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the relative distance. These repulsive force and attractive force are added to form the driving force for robot motion. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, since the usual potential field method initiates avoidance motion later than the proposed method, it sometimes fails preventing collision or causes hasty motion to avoid other robots. The proposed method works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning method for multiple robots to do a collaborative job.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.45-52
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• 2001

This paper presents a study on the position tracking control of a robot system on the uncertain elastic base. The elastic bathe is a nonholonomic system but it can be changed into holonomic system, which is much easier to analyze, by modeling an elastic base as a virtual robot that has passive joints. Also, Jacobian operators, which represent the overall robot system including base movement, are defined and applied to the changed model. However, because base movements are not known, the exact Jacobian operators can＇t be estimated. The control algorithm proposed is that uses only Jacobians of a real robot as approximate Jacobian operators. Therefore the approximate Jacobian operators compensate the measured errors from external sensors. The proposed control strategy is evaluated by the simulation and experiment of a single-axis robot system on the elastic base.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.10 s.115
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• pp.1082-1089
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• 2006

In this study, advanced computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling Independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Wavier-stokes equations with one equation Spalart-Allmaras and two-equation SST ${\kappa}-{\varepsilon}$ turbulence models are solved for unsteady flow problems and also relative moving and vibration effects of the rotor cascade are fully considered. A coupled implicit time marching scheme based on the Newmark integration method is used for computing the governing equations of fluid-structure interaction problems. Detailed vibration responses for different flow conditions are presented and then vibration characteristics are physically investigated in the time domain as computational virtual tests.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.5
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• pp.445-450
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• 2005

In this paper, we suggest an integrated tactile display system that provides kinesthetic force, pressure distribution, vibration and slip/stretch. The system consists of two parts: a 2 DOF force feedback device for kinesthetic display and a tactile feedback device for displaying the normal stimulation to the skin and the skin slip/stretch. Psychophysical experiments measure the effects of fingerpad selection, the direction of finger movements and the texture width on tactile sensitivity. We also investigate the characteristics of lateral finger movement while subjects perceive different textures. From the experimental results, the principal parameters for designing a tactile display are suggested. A tactile display device, using eight piezoelectric bimorphs and a linear actuator, Is implemented and attached to a 2 DOF translational force feedback device to simultaneously simulate the texture and stiffness of the object. As a result, we find out that the capability of the suggested device is sufficient to display physical quantities to display the texture.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.4 s.304
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• pp.127-132
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• 2005

The curve of motion indicated to waveform of the fast movement of human extracted using virtual reality or the quantity of time fluctuation of the electromagnetic signal as the quantity of electric fluctuation of the atmosphere is complex. It is important to decide exactly the signal property as the inflection point for the observation signal. When the signal is mixed by noise signal, the traditional method is difficult to detect the inflection point. In this paper the noisy signal is eliminated by wavelet thresholding method and the filter using natural observation theorem is applied. It shows that the inflection point of the signal waveform can be detected exactly.