• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.186-189
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• 2004

A thermal model of carbon spun yam is presented. The unit cell of spun carbon yam is divided into a number of volume elements and the local material properties have been given to each element. By using Finite Difference Method (FDM), temperature distribution in the unit cell can be obtained. Effective thermal conductivity of the spun carbon yam unit cell is calculated using the temperature distribution and thermal conductivities of local elements.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2482-2487
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• 2007

Numerical simulations are conducted for the analysis of a thermal mass air flow sensor with periodic heating pulses on silicon-nitride ($Si_3N_4$) thin membrane structure. This study aims to find the locations of temperature sensors on the thin membrane and the heating pulse conditions, that the higher sensitivity can be achieved, for the development of a MEMS fabricated mass air flow sensor which is driven in periodic heating pulse. The simulations, thus, focus on the membrane temperature profile according to variation of the flow velocity, heating duration time and imposed power. The flow velocity of the simulations is ranging from 3 m/s to 35 m/s, heating duration time from 1 ms to 3 ms and imposed power from 50 mW to 90 mW. The corresponding Reynolds numbers vary from 1000 to 10000.

• Journal of the Korea Fashion and Costume Design Association
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• v.19 no.2
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• pp.39-48
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• 2017

Transfer printing is a method to combine printing and dyeing technology by the use of sublimation. It is an environmentally-friendly printing method that saves costs, reduces the production processes by the omission of the washing process, and saves time by maintaining quality. Due to the development of transfer printing, a high value added printing technology is available now but color fastness to sublimation of the printing products is still low since there are few dyes that have an affinity to the fabrics and the application technology is still inadequate. Specially, in case of high concentration black dyes, eco-label type black dyes, which is a substitution for general dispersal dyes, have been developed while general dispersal black dyes are still used, creating issues such as color differences on the surface and back side of the fabrics and contamination by friction after transfer printing. There are also some restricted substances such as allergens. To address these issues, high concentration black dyes and application technology that are environmentally-friendly and that have over 16 K/S through the use of single dyes with excellent color fastness, fixation ability, and similar melting temperature were developed for this study.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1288-1293
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• 2007

The present study covers the design and analysis of a thermionic scanning electron microscope (SEM) column. The SEM column contains an electron optical system in which electrons are emitted and moved to form a focused beam, and this generates secondary electrons from the specimen surfaces, eventually making an image. The electron optical system mainly consists of a thermionic electron gun as the beam source, the lens system, the electron control unit, and the vacuum unit. In the design process, the dimension and capacity of the SEM components need to be optimally determined with the aid of finite element analyses. Considering the geometry of the filament, a three-dimensional (3D) finite element analysis is utilized. Through the analysis, the beam emission characteristics and relevant trajectories are predicted from which a systematic design of the electron optical system is enabled. The validity of the proposed 3D analysis is also discussed by comparing the directional beam spot radius. As a result, a prototype of a thermionic SEM is successfully developed with a relatively short time and low investment costs, which proves the adoptability of the proposed 3D analysis.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.1
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• pp.8-14
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• 2018

Printed circuit heat exchangers (PCHEs) are widely used with an increasing demand for industrial applications. PCHEs are capable of operating at high temperatures and pressure. We consider a PCHE as a candidate intermediate heat exchanger type for a high temperature gas-cooled reactor (HTGR). For conventional application using stainless steels, design and manufacturing of PCHEs are well established. For applications to HTGR, knowledge of longitudinal conduction and deformation of channel is required to estimate design margin. This paper analyzes the effects of longitudinal conduction and deformation of channel on thermal performance using a code internally developed for design and analysis of PCHEs. The code has a capability of two dimensional simulations. Longitudinal conduction is estimated using the code. In HTGR operating condition, about ten percent of design margin is required to compensate thermal performance. The cross-sectional images of PCHE channels are obtained using an optical microscope. The images are processed with computer image process technique. We quantify the deformation of channel with dimensional parameters. It is found that the deformation has negative effect on structural integrity. The deformation enhances thermal performance when the shape of channel is straight in laminar flow regime. It reduces thermal performance in cases of a zigzag channel and turbulent flow regime.

• The Research Journal of the Costume Culture
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• v.21 no.5
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• pp.684-698
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• 2013

Interest and desire for analogue emotion increased with the dazzling development of digital technology. Especially, as analogue emotion got grafted in the design field, analysis through various expression media is being done. This study seeks to propose design of t-shirt using unique advantage of Hangeul calligraphy that can satisfy the modern flow and pattern design's various expressions. Calligraphy is being used in various fields such as advert, package, logo, movie poster, signboard, graphic design, calligraphy and abstract painting. Formative yet effective in readability and conveying meaning as it's expressed in letters, calligraphy is a field of attention with its contribution in extending the new design area. As a method of the study, altogether 8 pieces of t-shirts were proposed through related preceding research, literary research, co-work with calligraphy author, computer graphic program, and heat transfer. As such, the t-shirt designs which were created by suggesting various design and using traditional materials like calligraphy, can be used as novel and sensual factor, where one can get a glimpse at the potential of development as traditional fashion product.

• Journal of Ocean Engineering and Technology
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• v.31 no.2
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• pp.103-110
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• 2017

The temperature of subsea pipeline, approximately as high as $100^{\circ}C$, is significantly higher than the temperature of surrounding sea water and sediment. In this reason, heat can be lost from the subsea pipeline to cause serious operation problem. Therefore it is important that the subsea pipeline must be designed to ensure that heat loss is small enough. Heat loss of unburied pipeline is higher than buried pipeline. For that purpose, trenching and backfilling system is a commonly used method for maintaining flow assurance in subsea pipeline installation. For this commonly used method, knowing thermal conductivity of backfill is essential to protect a heat loss of pipeline. This paper presents thermal conductivity of backfill soil using laboratory model test and numerical analysis for various backfill. In conclusion, it can be seen that higher the sand content of the man-made backfill sample, the higher the thermal conductivity. On the other hand, as the water content increases, the thermal conductivity becomes smaller.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.90-93
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• 2005

A thermal model of carbon spun yarn and its composite is presented. Based on voxelization method, the unit cells of spun carbon yam and its composite are divided into a number of volume elements and the local material properties have been given to each element. By using Finite Difference Method, temperature distribution in the unit cell can be obtained. Effective thermal conductivity of unit cell is calculated using the temperature distribution and thermal conductivities of local elements.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.18-23
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• 1985

전자계산기의 급격한 발달로 비선형방정식의 해가 쉽게 구해짐에 따라 이 방면의 연구가 괄목할 만한 진전이 이루어졌다. 전도(cond uction)문제도 단상은 물론 이상문제나 또는 기.백.고체의 삼 상문제로의 점점 복잡한 문제의 해도 가능하게 되었다.(1-5) 전자계산기도 그 용량이나 속도가 빨라짐에 따라 계산비용이 염가해지는 한편 해를 구하는 algorithm도 소형 computer의 적은 기 억용량으로도 쉽게 해를 구할 수 있는 program이 속속 개발되고 있는 실정이다.(6-7) 따라서 실측실험이 불가능한 영역이나 또는 가능하다 하여도 막대한 비용이 드는 경우에는 우선 수치 계산으로 그 결과를 예측하여 설계나 product improvement을 기해 보는 것이 바람직하다고 사 료되어 삼상이 공존하는 복잡한 영역의 열전달문제에 대한 수치연구 과정의 예로서 이야기 해 보고저 한다.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.338-341
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• 1997

The current consumption and the heat produced in the printhead of thermal printer are mainly governed by total printing dots and printing time for each line. Simple algorithm is proposed to optimize the performance of a thermal printhead, which use variable division according to bit-mapped data of its 1 line. And, for protecting the thermal printhead from exceeding heat, I control the heat energy of each microheater(dots) on the thermal printhead through changes in the applied pulse width.