• Transactions of Materials Processing
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• v.30 no.2
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• pp.69-73
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• 2021

This paper addresses the product shape modification for spring-back reduction in the sheet metal forming process of the cabin sunroof which is applied to the construction equipment. Initially, the anisotropic material properties are measured in order to calculate the degree of spring-back by the numerical simulation of the sheet metal forming process. To reduce the spring-back of the stamped part, several design modifications are suggested according to the geometrical bead arrangement on the planar region. The degrees of spring-back are confirmed for various product designs with different use of the geometrical bead. Finally, the spring-back improvement was validated by manufacturing the tryout product with the modified die set for the optimized product shape.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.224-230
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• 2013

Laser Lift-Off (LLO) is a process that removes a GaN or AIN thin layer from a sapphire wafer to manufacture vertical-type LEDs. It consists of a light source, an attenuator, a mask, a projection lens and a beam homogenizer. In this paper, we design an attenuator and a projection lens. We use the 'ZEMAX' optical design software for analysis of depth of focus and for a projection lens design which makes $7{\times}7mm^2$ beam size by projecting a beam on a wafer. Using the 'LightTools' lighting design software, we analyze the size and uniformity of the beam projected by the projection lens on the wafer. The performance analysis found that the size of the square-shaped beam is $6.97{\times}6.96mm^2$, with 91.8 % uniformity and ${\pm}30{\mu}m$ focus depth. In addition, this study performs dielectric coating using the 'Essential Macleod' to increase the transmittance of an attenuator. As a result, for 23 layers of thin films, the transmittance total has 10-96% at angle of incidence $45-60^{\circ}$ in S-polarization.

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.115-116
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• 2006

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.3
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• pp.304-311
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• 2011

This study selects camellia flowers as a material for design development and created patterns by simplifying the image of camellia flowers and combining it with a geometrical motif. It it applied them to various fields to develop design content for fashion cultural products that were Korean, modern, and competitive. For this purpose, this paper used Adobe Illustrator CS2 to turn the camellia flower into a motif and develop it into a pattern. Based on the realistic form of camellia flower, this paper set 3 basic motifs of new formative images, using graphic elements, such as omission of a form, simplification, overlapping, repetition, and reduction, and it also developed two transformed motifs by applying a different color to each motif. This paper repetitively arranged each motif in the background of a diamond shape, a square, and a circle, and it combined each motif with the patterns of marcel, stairs, and stripes, through which it expressed the combination of the geometrical patterns and the flower patterns. Through the application of repetitive and combined patterns of each motif, the enlargement and reduction of motifs, the repetition of motifs, the combined use of motifs, and the change in colors and layout, this paper used the motifs of various fashion cultural products, such as scarves, neckties, and T-shirts.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.4
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• pp.378-385
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• 2004

Viscous-driven pumping is a very promising type in microscale applications. However, there exist a few disadvantages such as low efficiency and small volume flow rate. In the present study, a pump with tandem rotating cylinders and its optimum synthesis are proposed fur enhancing pumping performance. First, using an unstructured grid CFD method, we investigate the effects of geometrical parameters and then the performance of the pump with tandem cylinders is evaluated. Next, an optimum design synthesis tool is constructed by combining the aforementioned CFD analysis model with the mathematical optimization model, namely, Modified Method of Feasible Directions (MMFD). This technique is used to optimize the geometrical parameters of the pump, fur maximizing pumping efficiency. From the optimization results, it is believed that the present optimum synthesis is robust and has a potential fur other microfluidic device design.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2893-2912
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• 2013

The design of geometrically invariant watermarking is one of the most challenging work in digital image watermarking research area. To achieve the robustness to geometrical attacks, the inherent characteristic of an image is usually used. In this paper, a geometrically invariant image watermarking scheme using connected objects and gravity center is proposed. First, the gray-scale image is converted into the binary one, and the connected objects according to the connectedness of binary image are obtained, then the coordinates of these connected objects are mapped to the gray-scale image, and the gravity centers of those bigger objects are chosen as the feature points for watermark embedding. After that, the line between each gravity center and the center of the whole image is rotated an angle to form a sector, and finally the same version of watermark is embedded into these sectors. Because the image connectedness is topologically invariant to geometrical attacks such as scaling and rotation, and the gravity center of the connected object as feature points is very stable, the watermark synchronization is realized successfully under the geometrical distortion. The proposed scheme can extract the watermark information without using the original image or template. The simulation results show the proposed scheme has a good invisibility for watermarking application, and stronger robustness than previous feature-based watermarking schemes against geometrical attacks such as rotation, scaling and cropping, and can also resist common image processing operations including JPEG compression, adding noise, median filtering, and histogram equalization, etc.

• The Research Journal of the Costume Culture
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• v.10 no.6
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• pp.763-780
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• 2002

The aim of this research is to analyze Vionnet´s geometric features, which can be regarded as the key formative beauty among the external characteristics of her works. and to thereby establish the theory that her works emitted a time-transcending life force because they were patterns designed based on a geometrical frame of mind. To prove such argument, studies to understand the basic geometrical aspects appearing in her works will be made by taking a look at the general features of geometry, viewing Vionnet´s philosophy for designing, and examining the geometric cutting methods. The period covered in this paper will center mainly on dresses Vionnet made from her very active days in the fashion sector, 1919. till when she retired from the fashion industry, around 1939. What's outstanding about Vionnet´s geometric principle expressed in her works is the unique cutting method that acknowledges the silhouette of the human body as a cubic or three-dimensions concept, through insight of the human body, the mechanics of the materials, and geometry. Vionnet introduced a simple and elegant design by combining geometric figure cuts, such as rectan히es. quadrants, and triangles. Moreover, she created a new sewing structure that plans everything about the materials to the tiniest detail, resulting in producing a softer style With this, Vionnet showed the geometrical correlation can bring about harmony and the beauty of ideal proportion, forming the source of eternal beauty. As discussed so fu, the geometrical characteristics appearing in Vionnet´s works are marked such as spirals, zig-zag lines, asymmetries. panels, gradation, golden proportion, and the mobius-band.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.150-157
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• 2009

In the 1970's the Interior Design Associations was established and the activity of youth designers who werecalled the "first generation of Korean interior designers" were created. This study is aimed to analyze characteristics and trends of commercial interior design in the 1970's. The design methods include the documentary research and the actual proof research conducted. The frames of analysis were made by the background theories about Korean interior design, and the annual case studies were analyzed and estimated according to the design types. The design types were analyzed by the geometrical simplicity research, the romantic emotional expression, the Korean identity expression, the machine technical asthetic expression and the eclectic style with western classics. In the early 1970's, the abstract, brief, and simple expression were presented most frequently by the geometrical form and the repetition of the pattern. From the mid-1970's the romantic and emotional atmosphere of the youth culture that was popular at that time were expressed as vernacular design by the rough finishing of the natural materials such as plaster, brick, and wood floorings etc. The space such as a Korean food restaurant relates to the Korean traditional culture aims to be different through the expression by the Korean traditional patterns, furniture, and materials. In the late 1970's the metals and glass were used for the expression of the machine aesthetic form but was not popular because of the rare application. The type that revived the past western traditional form was presented by using the arch, dome, and the curved and luxurious moldings.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.347-354
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• 2004

Using an efficient adjoint variable method, we develop a unified design sensitivity analysis (DSA) method considering both steady state nonlinear heat conduction and geometrical nonlinear elasticity problems. Design sensitivity expressions with respect to thermal conductivity and Young's modulus are derived. Beside the temperature and displacement adjoint equations, another coupled one is defined regarding the obtained adjoint displacement field as the adjoint load in temperature field. The developed DSA method is shown to be very efficient and further extended to a topology design optimization method for the nonlinear weakly coupled thermo-elasticity problems using a density approach.

• Journal of the Korean Society of Costume
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• v.59 no.9
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• pp.1-15
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• 2009

This study aimed to create a new costume design suitable for publicizing our traditional patterns in the world by using the traditional patterns of Northeast Asia region. The result of this study can be summarized as follows. First, China is characterized by a strictly fixed configuration and a realistic description, Japan a simplistic modality and an abstract-geometrical pattern, and Korea a eclectic type, whole-pattern, and part-pattern. This study aimed to make the pattern by using harmoniously these characters. Second, Korea, China, and japan have many similarities concerning a symbolism and a type of pattern. In the modern fashion, they often use dragon patterns, various flower patterns like peony, plum blossom, or mum, and geometrical patterns. This study focused on expressing patterns which contain the ornamental symbolism of Oriental Look, aside from an existing symbolism, and show a traditional sentiment of Northeast Asia. The method for expressing traditional patterns usually included weaving, dyeing, embroidery, or gold foil. Although these methods have been used in all the three nations, even rubbed metal foil and patchwork have been widely used in Japan.