• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.311-314
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• 2004

The housing of the fuel injector supports the rod, the niddle valve and the solenoid. Based on the procedure of process design, in this paper, the forming operation is designed by the rigid-plastic finite element method. The metal flow during the forming of the fuel injector housing is axisymmetric until the final forming process. The response surface method has been performed to reduce the under-fill and the maximum effective strain. From the results of RSM, the second order regression model of equation is calculated by the least square method and used to determine the optimal values of design variables by simultaneously considering the responses. It is noted that upper under-fill is affected by the design variables of the $2^{nd}$ forming process and lower under-fill is affected by the design variables of the 1st forming process.

• ETRI Journal
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• v.30 no.4
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• pp.535-545
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• 2008

This paper introduces a systematic top-down and bottom-up design methodology to assist the designer in the implementation of continuous-time (CT) cascade sigma-delta (${\Sigma}{\Delta}$) modulators. The salient features of this methodology are (a) flexible behavioral modeling for optimum accuracy-efficiency trade-offs at different stages of the top-down synthesis process, (b) direct synthesis in the continuous-time domain for minimum circuit complexity and sensitivity, (c) mixed knowledge-based and optimization-based architectural exploration and specification transmission for enhanced circuit performance, and (d) use of Pareto-optimal fronts of building blocks to reduce re-design iterations. The applicability of this methodology will be illustrated via the design of a 12-bit 20 MHz CT ${\Sigma}{\Delta}$ modulator in a 1.2 V 130 nm CMOS technology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.105-110
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• 2007

In this paper, a microstripline-type linear amplitude equalizer is implemented to achieve the linearity of the slope of the amplitude over $6{\sim}18$ GHz with resistors inserted between their immediate pairs of a TX-line and a stub. The values of resistors and stubs are explored to have the optimal linear slope and return loss performance. Experiments reveal the slope of around 9 dB variation and return loss of less than 10 dB desired over $6{\sim}18$ GHz and validate the design methodology.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.4
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• pp.293-299
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• 2015

Various centrifugal compressors are currently used extensively in industrial fields, where the design requirements are more complicated. This makes it more difficult to determine the optimal design point of a centrifugal compressor. Traditionally, the efficiency is an important factor for optimization. In this study, the weight of the compressor was also considered. The aim of this study was to present the design tendency considering the stage efficiency and weight. In addition, this study suggested possibility of a selection of compressor design objectives at an early design stage based on the optimization results. Only a vaneless diffuser was considered in this case. The Kriging method was used with sample points from 1D design program data. The optimal points were determined in a substitute design space.

• Journal of Pharmaceutical Investigation
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• v.33 no.3
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• pp.163-169
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• 2003

In order to develop a film-forming transdermal drug delivery system, polyurethane (PU) based on poly(ethylene glycol) and poly(tetramethylene oxide) was synthesized and characterized. The synthesized PU was blended with Gantrez ES 225 (GT) to improve the adhesion property of film-forming agent to the skin. When film-forming gel formulation containing 3% ketoprofen (KP) was applied, transparent thin film was obtained within 5 minutes and adhered to the skin for 8 hours. In vitro percutaneous absortion studies were performed to determine the rate of ketoprofen absorption through guinea pig skin. A prominent effect of limonene on the skin permeability of ketoprofen was observed among the various skin permeation enhancers investigated. Considering mechanica properties of film and skin permeability of ketoprofen, 2% of limonene was optimal content in the film forming transdermal formulation.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.86-90
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• 2018

Standards related to express the non-flatness of a wafer are reviewed and discussed, for example, bow, warp, and sori. Novel wafer warpage measurement method is proposed for 3D stacked IC application. The new way measures heat transfer from a heater to a wafer, which is a function of the contact area between these two surfaces and in turn, this contact area depends on the wafer warpage. Measurement options such as heating from room temperature and cooling from high temperature were experimentally examined. The heating method was found to be sensitive to environmental conditions. The cooling technique showed more robust and repeatable results and the further investigation for the optimal cooling condition is underway.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1572-1579
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• 2009

In this dissertation ultra-broadband power amplifier(UPA) was designed and fabricated using negative feedback technique. UPA was made of pre-amplifier, drive amplifier and power amplifier. Negative feedback technique was used to achieve ultra-broadband performance. Designed power amplifier has 30dB gain and 2W output power. The load-pull data of power amplifier for optimal power matching was extracted from the measured S-parameter. Fabricated PCB material, permittivity is 4.6 and thickness is 0.8mm, is FR4 and UPA was fabricated 3 modules for comparison of the simulated and measured results. Size of the fabricated pre-amplifier and drive amplifier module is 40mm'50mm'16mm. And from the experimental results, gain of the pre-amplifier module is 9.87dB at 2GHz and flatness is 0.63dB. Experimental result of the drive amplifier module is 10.97dB at 2GHz and flatness of that is 0.26dB. Test result of the power amplifier module is 10.71dB at 2GHz and flatness is 0.72dB. Total size of the power amplifier is 45mm'134mm'16mm. According to the test results, gain of the UPA is 28.98dB at 2GHz and flatness is 1.68dB. Output power was 32.098dBm at 2GHz, 32.154dBm at 1GHz and 31.273dBm at 100MHz.

• The Research Journal of the Costume Culture
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• v.30 no.3
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• pp.403-413
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• 2022

The purpose of this study was to develop a 3D mesh-type impact protection pad with excellent motion adaptability and functionality by applying 3D printing technology. The hexagonal 3D mesh, which constitutes the basic structure of the pad, comprises two types: small and large. The bridge connecting the basic units was designed as the I-type, V-type, IV-type, and VV-type. After evaluating the characteristics of the bridge, it was found that the V-type bridge had the highest flexibility and tensile elongation. The hip joint pad and knee pad were completed by combining the hexagonal 3D mesh structure with the optimal bridge design. The impact protection pad was printed using a fused deposition modeling-type 3D printer with a filament made of thermoplastic polyurethane material, and the protection pad's performance was evaluated. When an impact force of approximately 6,500N was applied to the pad, the force attenuation percentage was 78%, and when an impact force of approximately 8,000N was applied, the force attenuation percentage was 75%. Through these results, it was confirmed that the 3D-printed impact protection pad with a hexagonal 3D mesh structure connected by a V-shaped bridge developed in this study can adapt to changes in the body surface according to movement and provides excellent impact protection performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.288-296
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• 1992

This paper describes an improved 2D QPS(quadrature polar separable) filter design and its applications to texture processing. The filter kernel pair consists of the product of a radial weighting function based on the finite PSS (prolate spheroidal sequences) and an exponential at tenuation function for the orientational angle. It is quadrature and polar separable in the frequency domain. It is near optimal in the energy loss because we let the orientational angle function approximate the radial weighting function. The filter frequency characteristics is easy to control as it depends only upon the design specifications such as the bandwidth, the directional angle, the attenuation constant, and the shift constant of the central frequency. Some applications of the filter in texture processing, such as the generation of the texture image, the estimation of orientation angles, and the segmentations for the synthetic texture image, are considered. The result shows that the filter with the wide bandwidth can be used for the generation of discrimination of the strong orientational textures and the segmentation results are good.

• Journal of the Korea Fashion and Costume Design Association
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• v.26 no.3
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• pp.129-143
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• 2024

This study aims to develop yoga wear for active senior women aged 50-60 who engage in social activities based on time and economic availability. With the rapid growth of the elderly population, active seniors have become prominent consumers, showing a keen interest in cultural and sports activities, particularly yoga, which suits their physical structure and characteristics. Despite the increased interest in home training and healthcare post-pandemic, research on active senior's athleisure wear remains insufficient compared to younger demographics. This study conducted a literature review to understand the characteristics of active seniors and their needs for yoga wear, followed by a survey of 24 women aged 50 and above who practice yoga. The survey was conducted to assess yoga participation, current yoga wear usage, and design preferences. Results indicated that most respondents practiced yoga for less than a year, primarily for health and stress relief. While 65.2% were aware of specialized yoga brands, only 50% wore them, citing high prices and size mismatches as barriers. Functionality was the most critical factor affecting yoga wear purchase decisions, followed by design, material, and color/pattern preferences. Preferred top designs included V-neck, crew neck, and cowl neck with three-quarter sleeves, while leggings with a full-band waist were favored for bottoms. The study highlights the need for affordable, functional, and size-diverse yoga wear for active senior women, suggesting that modern, sophisticated designs are more appealing to this demographic. These findings provide essential guidelines for developing yoga wear that meets the specific needs of active senior women. As a result, this research has suggested three different yoga wear designs for active seinor women, using 3D Clo.