• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.209-212
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• 2006

Line heating with water cooling is generally adapted process in the shipyards for the forming hull surface. The purpose of this paper is to develop a model of thermal deformation in water cooling process after the line heating. In order to simulate the cooling process, heat transfer analysis was performed by assuming the effects of water cooling as a negative heat-source. Experiment for the line heating with water cooling was performed for 9 models of plates in order to verify the cooling model. By using the suggested model for the water cooling process, it could be observed that the present method predict the plate deformations in the line heating more accurately.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.1
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• pp.89-96
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• 2015

In this paper, it is studied that kinematic analysis of a 5-axis ultrasonic inspection equipment. The equipment is comprised of three straight axes and two rotary axes. With features of ultrasonic, the transmitter and receiver of the equipment are vertical to a test surface, operating at regular intervals. To perform this well, the motions of every link should be found on the based of kinematic analysis of the equipment. We chose starting point for testing and defined relations among all links through transformation of coordinates. For double curvature-shaped test object, we generated test paths. To follow these, we found motions of all links using inverse kinematics. By using Matlab/Simulink, simulator was developed, so that we could find out desired trajectories of main axes for a scan.

• Journal of Korean Society for Quality Management
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• v.28 no.2
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• pp.57-69
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• 2000

This paper discusses the local influence approach to the linear regression models with AR(2) errors. Diagnostics for the linear regression models with AR(2) errors are proposed and developed when simultaneous perturbations of the response vector are allowed- That is, the direction of maximum curvature of local influence analysis is obtained by studying the curvature of a surface associated with the overall discrepancy measure.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.144-149
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• 2005

This study presents the method of extracting shape design data on any aspheric lens by reverse engineering. The design formula fur aspheric lenses is needed in almost all of the design, manufacture and measuring processes. The difficulty in designing the lens lies in the fact that it uses a complex formula for the aspheric surface, and many of the preliminary design values must be selected before actually inserting them into the formula. If the values could be extracted from an aspheric lens for which the structural design information is unknown and used in designing other lenses of similar characteristics, the difficulties in designing and measuring aspheric lens could be reduced. Therefore, in this study, the concept of reverse engineering was applied to demonstrate the method of extracting shape design information of aspheric lens from an arbitrary aspheric lens.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.1
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• pp.39-46
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• 2007

The objective of this paper is to examine the detection limit, growth characteristics and notch curvature radius in short crack problem. Measurement techniques such as ultrasonic method and back-face strain compliance method were adapted. The fatigue crack growth rate of the short crack is slower than that of a long crack for a notched specimen. The short crack is detected effectively by ultrasonic method. A short surface crack occurs in the middle of specimen thickness and is transient to a through crack when maximum crack depth is larger than the notch curvature radius.

• Journal of the Korean Ceramic Society
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• v.25 no.6
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• pp.665-670
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• 1988

The behavior of mechanical properties of ion exchanged glasses was investigated in this study. The used glasses were soda-lime-silica glasses that were produced by float process. The maximum values of the bending strength and the curvature depth are 45Kg/$\textrm{mm}^2$ and 8.6mm respectively treated at 45$0^{\circ}C$ for 6h, which are 4.4 times and 3.3 times higher than parent glass. In the case, the thermalshock resistance ΔT is 335$^{\circ}C$ that is 205$^{\circ}C$ higher than parent glass, which is the maximum values in this study. The maximum values of the surface microhardness is 490Kg/$\textrm{mm}^2$ in case of 43$0^{\circ}C$ for 4h. It is also found out that annealing points are increased linearly with increasing the amount of K+ ion exchange independent of treatment temperature. Furthermore, the present work shows that the ion exchange strengthened glasses are more effective than the physical tempering glasses ; the bending strength and the curvature depth are 1.8 times and twice higher respectively.

• Proceeding of KASS Symposium
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• 2006.05a
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• pp.205-213
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• 2006

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cutting pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cooing pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cutting pattern generation using geodesic line, and investigate the result of example's cutting pattern in detail.

• The Transactions of the Korea Information Processing Society
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• v.6 no.3
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• pp.758-765
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• 1999

Shape-preserving property is the important method that controls the complex free form curve/surface. Interpolation method for the existed Shape-Preservation had problems that it has needed the minimization of a curvature-related functions for calculating single-valued data. Solving this problem, in this paper, it proposed to the algorithm of generalizing C piecewise parametric cubic that has shape-preserving property for both Single-value data and Multivalue data. When there are the arbitrary tangents and two data, including shape-preserving property, this proposed method gets piecewise parametric cubic polynomial by checking the relation between the shape-preserving property and then calculates efficiently the control points using that. Also, it controls the initial shape using curvature distribution on curve segments.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.3
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• pp.245-254
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• 2000

This paper proposes a new discrete curvature error metric to generate LOD meshes. For mesh simplification, discrete curvatures are defined with geometric attributes, such as angles and areas of triangular polygonal model, and dihedral angles without any smooth approximation. They can represent characteristics of polygonal surface well. The new error metric based on them, discrete curvature error metric, increases the accuracy of simplified model by preserving the geometric information of original model and can be used as a global error metric. Also we suggest that LOD should be generated not by a simplification ratio but by an error metric. Because LOD means the degree of closeness between original and each level's simplified model. Therefore discrete curvature error metric needs relatively more computations than known other error metrics, but it can efficiently generate and control LOD meshes which preserve overall appearance of original shape and are recognizable explicitly with each level.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.8 s.145
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• pp.1168-1175
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• 2005

Clothing pressure has close relation with clothing comfort and depends on the pattern and properties of textile fabrics. Choosing a suitable clothing pressure is an essential factor for designing functional clothing such as the foundation for reshaping of a body contour or medical items for bum patient, and etc. However, it is hard to measure pressure values at the curved surface of a human body correctly. Recently, an air pack type pressure sensor, which has relatively excellent performance has been used to measure clothing pressure, however, it is still inconvenient to apply because it is a contact- type sensor. Therefore, in this paper, we suggest an indirect method that can measure clothing pressure without touching the subject by improving the equation of Kirk and Ibrahim (1966). However, confusions have been occurred when someone use the equation since the definition of parameters are somewhat vague. Furthermore, the estimated clothing pressure obtained by the previous method are quite different from the real values because this method does not consider the 3D effect of a human body and property changes of a transformed fabric. In this paper, the direction of principal stress and the radius of curvature in the principal direction were searched in the 3D image of the deformed girdle to get more accurate clothing pressure. The estimated clothing pressure was verified by comparing the result of the air pack type pressure sensor. It was found that the accuracy of the pressure estimation was improved by considering the 3D curvature of human body and the directional characteristics of textile fabrics.