• Journal of the Korea Computer Graphics Society
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• v.25 no.3
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• pp.123-131
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• 2019

In this study, we modified CT images of femoral head in consideration of anatomically meaningful structure, proposing the method to augment the training data of convolution Neural network for segmentation of femur mesh model. First, the femur mesh model is obtained from the CT image. Then divide the mesh model into meaningful parts by using cluster analysis on geometric characteristic of mesh surface. Finally, transform the segments by using an appropriate mesh deformation algorithm, then create new CT images by warping CT images accordingly. Deep learning models using the data enhancement methods of this study show better image division performance compared to data augmentation methods which have been commonly used, such as geometric conversion or color conversion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.1-11
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• 2022

In this study, an electric resistance dual-spot welding process using a copper electrode inserted in a heating electrode is suggested for the spot welding of AZ31 magnesium sheets. This spot-welding process involves two heating methods for welding at the interfacial zone between the magnesium sheets, one of which is the heating method by thermal conduction from the heating electrode heated by the welding current induced to the steel electrode, and the other heating method uses the electric resistance between the contacted surfaces of the two sheets by the welding current induced to the copper electrode. This welding process includes the welding variables, such as the current induced in the heating electrode and the copper electrode, and the outer diameters of the heating electrode. This is because the heat conducted from the heating electrode can be maintained at a higher temperature in the welding zone, which has a slow cooling effect on the nugget of the melted metal after the welding step. The pressure exerted during the pressing of the magnesium sheets by the heating electrode can be increased around the nugget zone at the spot-welding zone. Thus, it not only reduces the warping effect of the elastoplastic deformation of sheets, but also the corona bond can make it less prone to cracking at the welded zone, thereby reducing the number of nuggets expelled out of the corona bond. In conclusion, it was known that an electric resistance dual spot welding process using the copper electrode inserted in the heating electrode can improve the welding properties in the electric resistance spot welding process of AZ31 magnesium sheets.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.133-142
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• 1997

Most of the greenhouses employ the roll-up type ventilation control system. Torque required to roll-up and down might be theoretically expressed with the weight times radius of the ventilation roll; however, measured torques were two times of the theoretically estimated values. As the window film of roll-up vent is used over the periods of time, the warping and crumpling of the material caused the increase of the torque in addition to a span deformation. Therefore, this study was performed to develop an empirical torque formulae to present basic torque data and to assist the development of roll-up type ventilation control system. The empirically adjusted rolling radius (r＋a) exponentially increased at the maximum span deformation. The coefficient of rolling resistance (Cr) was about 0.7―0.8 depending upon the wrinkle status of film material.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.3 s.309
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• pp.67-75
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• 2006

Facial expressions exhibit not only facial feature motions, but also subtle changes in illumination and appearance. Since it is difficult to generate realistic facial expressions by using only geometric deformations, detailed features such as textures should also be deformed to achieve more realistic expression. The existing methods such as the expression ratio image have drawbacks, in that detailed changes of complexion by lighting can not be generated properly. In this paper, we propose a nonlinear model for skin color change and a model-based synthesis method for facial expression that can apply realistic expression details under different lighting conditions. The proposed method is composed of the following three steps; automatic extraction of facial features using active appearance model and geometric deformation of expression using warping, generation of facial expression using a model for nonlinear skin color change, and synthesis of original face with generated expression using a blending ratio that is computed by the Euclidean distance transform. Experimental results show that the proposed method generate realistic facial expressions under various lighting conditions.

• Journal of the Korean Geographical Society
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• v.49 no.2
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• pp.200-220
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• 2014

This study reexamines the old concept and reviews prevalent statements on Cenozoic vertical motions of the peninsula that have been uncritically repeated in our academia. The contents of this paper are redefinition of the notion, tilted flexure or warping, and a suggestion for a new time set and properties of the deformation, followed by a new model on its influencing factors and processes. In conclusion, the Cenozoic vertical motion of the Korean peninsula can be reified further with an epeirogenic movement of uplift in the east side-subsidence in the west side of the peninsula since the Neogene (23 Ma). However, the regional boundary for areas of uplift and subsidence is not likely in the Korean peninsula but broader farther to East China and the southern part of Russia. It can be best understood that mantle convection produced by subducting activities in the Western Pacific Subduction Zone causes the uplift and subsidence of earth surface around NE Asia. In addition, faultings in the upper lithosphere induced by in-situ plate boundary stresses accelerate regional uplift in the peninsula since the Quaternary. Controversies that are still standing such as current uplift movements along the western coast of the peninsula during the late Quaternary could be precisely discussed with future research providing detailed information on it.