• Journal of Advanced Research in Ocean Engineering
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• v.1 no.3
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• pp.148-156
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• 2015

Deck plates of ships or offshore structures would make out-of-plane distortion for their thin thickness. These distortions are usually straightened by thermal straightening such as flame heating method. After thermal straightening, the blocks are lifted and moved by cranes to assemble it at dry-dock stage. After this lifting process, out-of-plane deformation again happens frequently. And then, they continuously cause quality and accuracy problems in the final dry-dock process. So, it takes more time for repair and correction working. According to preceding research, the lifting process by cranes would offset the effect on thermal straightening. The target of this study is to develop a methodology analyzing the remaining efficiency of thermal straightening after block lifting. The development was based on the assumption of yield state at straightening region. Therefore the remaining efficiency was obtained by different stiffness slope while lifting & relieving. The efficiency formula was designed using inherent strain, and we made a table of zero-efficiency by cooling speed and class rule's steels. As a result, if the stress orthogonal to straightened line is calculated during lifting analysis by FEA, the efficiency can be obtained linearly to the values in the table. Finally, even optimized carling position can be designed by considering the regional data from series project and welding region on deck.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.2
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• pp.125-131
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• 2002

This paper presents MMIC drive and power amplifiers covering 6-18 ㎓. For simple wideband impedance matching and less sensitivity to fabrication variation, modified distributed topologies are employed in the both amplifiers. Cascade amplifiers with a self-biasing circuit through feedback resistors are used as unit gain blocks in the drive amplifier, resulting in high gain, high stability, and compact chip size. Self impedance matching and high-pass, low-pass impedance matching networks are used in the power amplifier. In measured results, the drive amplifier showed good return losses ($S_11,{\;}S_{22}{\;}<{\;}-10.5{\;}dB$), gain flatness ($S_{21}={\;}16{\;}{\pm}0.6{\;}dB$), and $P_{1dB}{\;}>{\;}22{\;}dBm$ over 6-18 GHz. The power amplifier showed $P_{1dB}{\;}>{\;}28.8{\;}dBm$ and $P_{sat}{\;}{\approx}{\;}30.0{\;}dBm$ with good small signal characteristics ($S_{11}<-10{\;}dB,{\;}S_{22}{\;}<{\;}-6{\;}dB,{\;}and{\;}S_{21}={\;}18.5{\;}{\pm}{\;}1.25{\;}dB$) over 6-18 GHz.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.113-120
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• 2005

Soil nailing system can be mentioned to a method of supporting as the shear strength of in-situ soils is increased by passive inclusions. In the general soil nailing system, facing walls are used in two kind of a lattice concrete block or a cast in placed concrete wall. A case of lattice concrete blocks is used in slow slopes greater than 1:0.7. Also, a case of a cast in placed concrete wall is used in steep slopes less than 1:0.5. The cast in placed concrete walls are constructed to 30cm thick together with a shotcrete facing. In this study, the assembling soil nailing method as a new soil nailing system is proposed. This method is constructed assembly using precast concrete panels. Therefore ability of the construction and quality of the facings can be modified than a usual soil nailing system. Also, this method can be obtained the effects that a global slope stability increase, as precast concrete panels is put on cutting face after excavating a slope.

• Textile Coloration and Finishing
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• v.26 no.2
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• pp.79-87
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• 2014

Dyeing fabric weaved with two or more kinds of fiber in different section has various dyeing interactions caused by different material properties of them. Newly developed knit fabric was used in this study. It composited by two different blocks, each block is included PET fiber and CDP fiber separately. Build-up properties with cation dyes and disperse dyes were good having average 83% of dyeing exhaustion yield on 5% o.w.f. dye concentration. As depending on dyeing methods, there were not showed direct interaction between cation dyes and disperse dyes. This result could be considered their different dyeing mechanism. Compatibility was best in S-type disperse dyes investigated their critical absorption range as $120^{\circ}C{\sim}130^{\circ}C$. Wash fastness was generally good in most dye.

• Journal of Welding and Joining
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• v.20 no.3
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• pp.109-115
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• 2002

In this study high power Nd:YAG laser welding of structural steel was investigated. For the test steel blocks of $50{\times}50{\times}200mm$ were cut and machined, and bead-on-plate weld was made on the machined surface. Argon, nitrogen, helium, dry air or mixed gases were used to find the effect of shielding conditions on the bead formation. Results demonstrated that there were Fe I rich region and Fe II rich region in the laser induced plasma column based on the spectral analysis with S-2000 field spectrometer The Fe I region was located at the root of the column near keyhole opening. On the other hand, Fe II region was found at the middle of the plasma column. In the Nd:YAG laser welding, Fe I region emitted continuum which had peak value at wave length of around 710nm, and Fe II region had the peak at 580nm. In the welding of steel by $CO_2$ laser, however, no continuum was observed. There showed two groups of strong spikes in the $CO_2$ laser welding; the first group was displayed at the wave band of 450-560nm. This spike group emitted stronger intensity of light and sharper peaks than those group at 680-800nm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1964-1969
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• 2012

This paper presents to verify the selective grounding fault protective relaying technique for the ungrounded DC traction power supply system. This system selectively blocks fault section when grounding fault occurred. In order to perform this verification, field test facilities have been installed on Oesam substation and Worldcup-Stadium substation, and field test process has been suggested. Also, selective grounding fault protective relaying components and rail voltage reduction device have been tested with the various trial examinations. In order to compare and evaluate performance of the selective grounding fault protective relaying function, field test system was modeled and the system fault simulation results were compared and evaluated with the field test result. Performance of selective grounding fault protective relaying function was evaluated with the above-mentioned process, and the fact that the system recognizes fault section irrespective of insulation between rail and ground and fault resistance from grounding fault.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.12
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• pp.1002-1010
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• 2016

This paper describes the design of a cellphone curved glass measuring device using by camera. The measuring device was composed of two camera, two backlight system, a body and so on, and the program was made for a camera calibration and noise removal, and also the program was made for height measurement of a cellphone curved glass using by subpixel algorism. And then a new technique for measuring the height of the cell phone curved glass was proposed. The characteristics test of height measurement of gage blocks and cell phone curved glasses was carried out, the error of the height measurement of gage block is less than ${\pm}0.005$ and the error of the height measurement of the cell phone curved glasses is less than ${\pm}0.005$. Thus it thought that the designed cellphone curved glass measuring device and the new technique for measuring the height was used to measure the height of the cellphone curved glass.

• Journal of the Korean Geosynthetics Society
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• v.3 no.1
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• pp.37-42
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• 2004

In the reinforced retaining wall system, non-woven geotextiles are placed at the face of reinforced earth until the facing blocks are built up. And when this system is used as temporary structure, geotextiles facings are exposed to sunlight during service lifetime. During these periods, degradation of nonwoven geotextiles are occurred by UV light. So the UV-resistance of nonwoven geotextiles must be assessed correctly, in considering of the site conditions. In this study, laboratory test and the field test have been performed to evaluate the UV resistance of non-woven geotextiles used in KOESWall system and the results are expressed in terms of tensile characteristics & SEM photographs.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.49-49
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• 2011

GNP 증가 등의 요인으로 생활수준이 향상되면서 사람들의 고급스럽고 아름다운 공간에 대한 선호도가 점점 증가하고 있으며 따라서 실내 인테리어 산업에 대한 관심이 높아지고 있다. 인테리어 산업에서 주로 사용되는 무늬목은 나무 모양이 나게 무늬를 새겨 넣어, 외양을 장식하는 얇은 합판으로 나무의 고급스러움과 아름다움으로 인해 고부가가치 상품으로 자리잡고 있으며 주로 실내인테리어장식 및 가구, 마루바닥, 건축내장재, 제재목 등의 건축 자제의 용도로 사용되고 있다. 또한 천연목재를 이용한 다양한 가공법으로 아름다운 무늬의 재현 등을 실제 이루고 있으며, 천연 목재의 색감 외 표백/염색/가공을 통한 염색무늬목 제조도 이루어지고 있는 실정이다. 무늬목 염색가공에 대한 기술이 보편화되지 않은 실정에서 고부가가치형 기술로 자리 매김 하기 위해서는 제조공정 시 보다 안정적인 작업성과 최소한의 작업 변수를 확보하는 것이 무엇보다도 중요하다. 이에 본 연구에서는 고부가가치형 무늬목의 생산성을 향상하고, 불량률의 최소화를 궁극적 목적으로 하며, 실제 침염목의 건조공정 중 최적의 함수율을 확보할 수 있는 예비건조 시스템을 개발 적용하여 시간과 에너지 절감 효과를 확보하였다. 생산 중 최대의 불량현상으로 갈라짐(건조로 발생한 응력에 의해 목리방향으로 갈라지는현상:checks)과 건조공정의 지연으로 발생하는 부패현상도 개선하였다.

• Transactions on Electrical and Electronic Materials
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• v.12 no.6
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• pp.241-244
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• 2011

An isolator transmits light in the forward direction and blocks light from passing in the reverse direction. It is regarded an essential optical component in medical, industrial, and research lasers for blocking reflection beams that cause optical damage and noise. It is also used as a communicative light intensifier to expand the lifespan of devices and enhance transmission quality. This study analyzed the characteristics of the core components in the construction of a polarization-independent isolator, namely, the walk-off polarizer and the Faraday rotator. Measurement of the extinction ratio of the resultant walk-off polarizer revealed that the ratio between the vertical and horizontal rays was 1,050:1 with a laser output of 0.032 W and 1,010:1 with a laser output of 2.68 W, thus presenting ratios similar to 1,000:1. In addition, the walk-off polarizer and Faraday rotator constructed in this study were used to compare output changes according to changes in power of input light and to check the penetration ratio. Results from the study presented variations in output value according to changes in power of input light. However, the average penetration ratio remained relatively consistent (~81.4%).