• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.817-824
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• 2016

In this paper, a modified elliptical lens antenna design is proposed to improve the performance of 100 GHz mini-lens antennas used in the ECEI(Electron Cyclotron Emission Imaging) module at KSTAR. A hemispherical lens is added on the bottom plate of the conventional elliptic lens antenna, and a 100 GHz dipole antenna is located on the end point of the hemispherical lens. Using geometrical optics, antenna radiated EM fields are designed to be totally reflected from the inner surface of the hemispherical lens, and thereby the antenna patterns are more focused toward the main beam. The validity of the proposed design is confirmed by the 3D EM simulator. The modified elliptical lens antenna provides 23.8 dB maximum gain, which is 2.2 dB gain improvement as compared with the conventional elliptic lens. Also, the side love levels of E- and H-planes are decreased by 2.6 dB and 3.4 dB, respectively.

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.10a
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• pp.58.2-58
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• 2001

• Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.67-72
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• 2015

Recently, along with the improvements of geometry modeling methods using sketch-based interface, there have been a lot of developments in research about generating surface model from 3D curves. However, surfacing a 3D curve network remains an ambiguous problem due to the lack of geometric information. In this paper, we propose a new algorithm for estimating the normal vectors of the 3D curves which accord closely with user intent. Bending energy is defined by utilizing RMF(Rotation-Minimizing Frame) of 3D curve, and we estimated this minimal energy frame as the one that accords design intent. The proposed algorithm is demonstrated with surface model creation of various curve networks. The algorithm of estimating geometric information in 3D curves which is proposed in this paper can be utilized to extract new information in the sketch-based modeling process. Also, a new framework of 3D modeling can be expected through the fusion between curve network and surface creating algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.4
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• pp.293-298
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• 2017

In this study, we developed a 3D chocolate printer and studied the conditions needed for chocolate printing. Because chocolate is a mixture of cocoa mass, cocoa butter and sugar particles, its properties vary with temperature, and care is required in melting and extrusion. A chocolate supply unit is composed of a heating block and a syringe pump. It is integrated with a 3-axis linear robot. In order to be more accurate than the existing 3D chocolate printer is, the system was configured so that the printing line width became $430{\mu}m$. Printing performance was studied according to various parameters. The condition needed for printing lines with a stable width was discovered by the experimental design method and has been confirmed by a 2D line test. These 3D printing experiments showed that it was possible to build a 3D shape with an inclination angle of up to $45^{\circ}$ without support. Further, chocolate printing of a 3D shape has been successfully verified with the developed system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.765-776
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• 2001

In this paper, a shaped offset gregorian antenna is electrically designed for Ku band FSS antennas of the domestic communications and broadcasting satellite which will be launched in the near future. For this, a design procedure for shaped offset gregorian antennas is described in detail, and a satellite antenna is designed by using the described design procedure. The radiation characteristics of the designed antenna are evaluated and compared with the design goals. The designed antenna is found to have 1.2$^{\circ}C$ beamwidth, 38.57 dBi EOC gain, and 43.19 dBi gain at Tx frequency 12.25 GHz and 1.08$^{\circ}$ beamwidth, 38.12 dBi EOC gain, and 44.11 dBi gain at Rx frequency 14.0 GHz. And also, side lobe levels and cross-polarization levels are less than -30 dB and -33 dB, respectively. From these results the designed antenna is found to be able to use for the domestic satellite FSS antennas.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1632-1652
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• 2011

This paper considers the object tracking problem in three dimensional (3-D) space when the azimuth and elevation of the object are available from the passive acoustic sensor. The particle filtering technique can be directly applied to estimate the 3-D object location, but we propose to decompose the 3-D particle filter into the three planes' particle filters, which are individually designed for the 2-D bearings-only tracking problems. 2-D bearing information is derived from the azimuth and elevation of the object to be used for the 2-D particle filter. Two estimates of three planes' particle filters are selected based on the characterization of the acoustic sensor operation in a noisy environment. The Cramer-Rao Lower Bound of the proposed 2-D particle filter-based algorithm is derived and compared against the algorithm that is based on the direct 3-D particle filter.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.2
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• pp.86-93
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• 2004

The DCT algorithm needs an efficient hardware architecture to compute inner product. The conventional design method, like ROM-based DA(Distributed Arithmetic), has large hardware complexity. Because of this reason, a CSHM(Computation Sharing Multiplication) was proposed for implementing inner product by Park. However, the Park's CSHM has inefficient hardware architecture in the precomputer and select units. Therefore it degrades the performance of the multiplier. In this paper, we presents the optimization design method for inner product using CSHM algorithm and applied it to implementation of 1-D DCT processor. The experimental results show that the proposed multiplier is more efficient than Park's when hardware architectures and logic synthesis results were compared. The designed 1-D DCT processor by using proposed design method is more high performance than typical methods.

• Fashion & Textile Research Journal
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• v.25 no.2
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• pp.139-152
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• 2023

Despite efforts to apply 3D print (3DP) technology in the field of fashion and endless discussions about the possibility of future development, in reality, it is difficult to utilize 3DP technology in fashion for reasons related to material, technology, and cost constraints. The purpose of this study was to supplement the limitations of 3DP technology in order to promote its utilization in fashion and simultaneously find a solution to achieve aesthetic satisfaction in the design method. Specifically, through the development of fashion products with a 3DP polymer-fabric structure to which the parametric design methodology has been applied, this study explored the possibility of practical application and proposes a new 3DP fashion design method. The 3DP polymer-fabric developed as a result of the research was stably adhered to the fabric. Additionally, the study confirmed the possibility of making 3DP clothes that are amenable to the wearer's activities, as it was verified that cutting and sewing tailored to the human body's curvature and structure can be performed. The design process using the 3DP polymer-fabric presented in this study is meaningful in that it suggests a solution to complement the limitations of modern technology in connection with designers' creativity. Moreover, the design process presented in this study is expected to contribute to the commercialization and generalization of 3DP by providing practical help to allow fashion experts to utilize 3DP technology.

• Korean Journal of Computational Design and Engineering
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• v.11 no.4
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• pp.303-314
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• 2006

The exchange of CAD (Computer Aided Design) models between different CAD systems and to downstream applications such as manufacturing has become very important to modem industry. One serious current issue is that the process cannot automatically import existing 3-D solid models in a variety of commercial CAD formats into the process without manually re-mastering the model in current standard including "SIEP AP(Application Protocol) 203 Edition 1" To fully integrate technical data from the design agency to the shop floor, design intent and validated 3D geometry of feature based parametric CAD model should be brought into the standardized processes. To overcome this limitation, AP203 Edition 2 (Ed.2) and its related STEP parts such as Part55, Part108, Part109, Part111 and Part112 are starting to be available to handle this problem. The features in Part111 are harmonized with the machining features available in AP224. This paper is focused on two mapping technologies: CAD to Part111 mapping and Pat111 to AP224 mapping including case studios and it will provide the guideline about what should be done next in the AP203 Ed.2 to AP224 mapping. The final goal of this project is to integrate technical data from CAD to AP224 based manufacturing information through AP203 Ed.2.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.961-966
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• 2003

In recent, the design of diaphragm which is representative disturbed region in PSC box girder bridge have been performed according to the empirical method or beam theory. But, these methods couldn't be described the behavior of the end diaphragm, and placed reinforcements accurately. As the compressive stress transferred by the web concentrated on the lower parts of diaphragm, it was demonstrated that the basic assumption of 2-D strut-and-tie model for the diaphragm that the compressive stress acts on the upper parts of the diaphragm is wrong. Meanwhile, in this research, after analyzing the variables of end diaphragm, the 2-D strut-and-tie models appropriate to each cases are proposed. And, the problems of 2-D strut-and-tie model were analyzed, so 3-D strut-and-tie model is proposed as well. There is no codes which include the demonstration of safety of 3-D strut-and-tie model. Hence, for nodes, the stresses at the elements which included the singular node in strut-and-tie model were investigated using the finite element analysis. And, the stress states of strut has one direction, so effective stresses were considered at the stage, dimensioning of the model. From the results, 3-D strut-and-tie model could predict the behavior of end diaphragm accurately, and design of reinforcement could be performed economically.