• 한국기계가공학회지
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• 제11권2호
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• pp.144-151
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• 2012

Polishing is not only one of the most frequently adopted processes in modern industries, but also the most critical one to the surface quality of the products such as semi conductor wafers and LED sapphire wafers. With the required specifications for the wafer surface quality getting more and more strengthened, the manufacturers are spending huge amount of cost to renew the machine to meet the enhanced surface specifications. Surface qualities of the wafers are mostly damaged by the structural vibrations of the polishing machines. In this paper, the dynamic characteristics of a wafer polishing machine have been analyzed through the frequency response test and the computer simulation. And the supporting structure of a polishing machine has been investigated to minimize the vibration transmissions, to improve the stability of the machine and further to reduce the defects of the polished products. The result of the study shows that simple design modifications of the supporting structure without altering the main structure of the machine can substantially suppress the vibrations of the machine with negligible expenses.

• 영어영문학
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• 제55권1호
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• pp.25-59
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• 2009

This study explores the characteristics of Elizabeth Bishop's poetry in comparison with the two of her closest friends and poets, Marianne Moore and Robert Lowell. Bishop's reputation has dramatically changed since her death. In the 1970s she was "a writer's writer's writer," and admired by a small group of poets or critics. Since 1990s, however, there has been a great shift in the evaluation of her poetry, which is so called "The Elizabeth Bishop Phenomenon." It does not seem to be an easy task to examine what has driven the phenomenon, and why she used to be a minor poet or "the most honored yet most elusive of poets" but now she has a widespread recognition by the academy and beyond it. The "intrinsic qualities" of Bishop's poetry, however, can be one of the main reasons why it took several decades for Bishop to become a central figure in the literary canon. Looking into her "intrinsic qualities," this paper discusses Bishop's "The Fish," "Roosters" through the Moore-Bishop relationship, and reads Bishop's "Armadillo" and "The Monument" through the Lowell-Bishop relationship. It also deals with letters, interviews, Moore's "The Fish," and Lowell's "Skunk Hour" and "For the Union Dead" to show the Bishop's deep and complex relationships with the two poets, and more importantly their differences. Bishop's poetry is difficult, "elusive," and sometimes "enigmatic," not because her texts are full of difficult words to understand but because there are the subtle interchange between perception and meaning, "the dynamics of keen feeling," the unresolved patterns, and the transient vision under the seemingly transparent surface of the texts.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1996년도 특별강연 및 추계학술발표 개요집
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• pp.139-141
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• 1996

Among various welding parameters, the welding current which is inversely proportional to the tip-to-workpiece distance in GMAW is an essential parameter to monitor the GMAW process of horizontal fillet joints. For the case of weld defect such as overlap in horizontal fillet welding, therefore, the signal processing for process monitoring or automatic seam tracking should be modified by considering the weld pool surface geometry including the corresponding weld defect. In other words, the adequate signal processing algorithm is indispensible to improve the performance of the arc sensor. However, arc sensor algorithm already developed usually focus on weld seam tracing but do not considering the weld qualities. In this paper, various experiments were carried out to investigate the tendencies of the weld defects when weaving motion is added, and the experimental method based on 2$^n$ factorial design was proposed for deriving the mathematical model between the leg length and the various welding conditions. Moreover, a signal processing method based on the artificial neural network(Adaptive Resonance Theory) was proposed far discriminating the current signal of sound weld beads from that of weld beads with overlap. Finally, the algorithm for weld seam tracking combined with the mathematical modeling and the signal processing method was carried out to track the weld line in conjunction with the improvement of the weld qualities. The reliability of the proposed algorithms were evaluated through various experiments, which showed that the proposed algorithms could be effectively used for arc welding automation.

• 한국식품과학회지
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• 제23권6호
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• pp.723-731
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• 1991

레토르트 카레 소스를 생산하기 위한 최적 살균 조건을 산출하기 위하여, $3^{2}{\times}2^{1}$ 요인 실험을 통하여 살균 온도, 시간 및 방법을 변화시켜 18개 조건에 대한 살균 공정이 행하여졌다. 살균 전후의 제품에 대한 품질평가 항목은 비타민(niacin) retention, pH, 색차 및 관능 검사(맛, 색상, 점도)등 이었다. 각 살균 조건에 대한 $F_{o}$ 값도 측정되었다. 살균 후 제품의 품질은 주로 살균 온도 및 시간에 의해 영향을 받았으며, 살균 방법에 의해서는 거의 영향을 받지 않았다. 품질을 저하시키는 영향에 있어 살균 시간의 연장이 살균 온도의 상승보다 큰 영향을 나타내었는데, 이는 고온 단시간 살균의 장점을 제시해준 결과라 하겠다. 반응 표면 분석에 의해 추정된 최적 살균 범위는 $123.5^{\circ}C$, 21.5분-$127.5^{\circ}C$, 17분 부근이었다. 이 범위에서 측정된 냉점에서의 $F_{o}$ 값은 15분 정도였다.

• 한국식품조리과학회지
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• 제26권4호
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• pp.398-405
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• 2010

In this study, white bread was prepared containing 1.5, 3.0, 4.5 or 6.0% barley leaves tea powder (BLTP). The samples along with a control were then compared regarding their quality characteristics, including pH, total titratable acidity, fermentation power of dough expansion, specific volume, baking loss, moisture content, color, textural characteristics, internal surface appearances and sensory qualities, all to determine the optimal ratio of BLTP. As the BLTP content increased, the pH of the dough and bread and the lightness decreased, whereas the total titratable acidity increased. The fermentation power of dough expansion increased with a longer incubation time. The control group was evidenced by a significantly higher specific volume and baking loss than that observed in the BLTP samples. However, greenness and yellowness evidenced the opposite effect. Hardness was highest at a substitution level of 1.5% and lowest at a level of 4.5%. Fracturability and resilience were not significantly different among the samples. For the internal surface appearance, darkness and greenness increased both increased at higher BLTP content. In the sensory evaluation, color, flavor and overall acceptability were highest in the control bread samples but minimal at a substitution level of 6.0%. Softness was the highest at the 3.0% substitution level and lowest in the control bread samples. Barley leaf flavor, astringency, bitterness and off-flavor increased as the BLTP content increased. Delicious taste was not significantly different among the samples. In conclusion, the results demonstrated that 4.5% BLTP may prove quite useful as a substitute for wheat flour in the production of white bread and may provide favorable nutritional and functional properties.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제21권1호
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• pp.67-76
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• 2015

Purpose : The current tactile walking surface indicators have not been easily accessible to blind and vision-impaired people due to unexpected variation of walking environment and walking behavior of transportation poor. Moreover, those indicators frequently cause the inconvenience to transportation users' walking. Thus, this study aims to investigate the improvement of tactile walking surface indicators, by comparing and analyzing findings from the relevant research. Results from this study contribute to suggest the better standard criteria of tactile walking surface indicators for transportation users, especially blind and vision-impaired people, the handicapped, the child and the elderly and weak, providing the secure and convenient circumstance for walking. Method : This study presents the problems about the standard criteria of tactile walking surface indicators via the examination of finding from the past studies. For example, we examine all standard criteria, focusing on shapes, colors and qualities of materials used for Tactile Walking Surface Indicators. Then, the present study suggests the improvement of standard, which apply to the current walking environment practically and reasonably. Results : To improve the current condition of tactile walking surface indicators, the analysis on international and domestic standard criteria need to be conducted. Findings from these analyses helps to suggest the better criteria for the interval between projecting points of tactile walking surface indicators, effective perceived range of walking road, and the brightness contrast between tactile walking surface indicators and finishing materials. Implication : The suggested standard criteria of tactile walking surface indicators need to be tested by transportation users, and the practical instructions of establishing tactile walking surface indicators should also be developed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.735-738
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• 2000

The characteristics of wire electrical discharge machining (WEDM) are governed by many factors such as the power supply type, operating condition and electrode material. This work deals with the effect of wire electrode materials on the machining characteristics such as, metal removal rate, surface characteristics and surface roughness during WEDM A wire's thermal physical properties are melting point, electrical conductivity and vapor pressure. One of the desired qualities of wire is a low melting point and high vapor pressure to help expel the contaminants from the gap. They are determined by the mix of alloying elements (in the case of plain brass and coated wire) or the base core material(i.e. molybdenum). Experiments have been conducted regarding the choice of suitable wire electrode materials and influence of the properties of these materials on the machinability and surface characteristics in WEDM, the experimental results are presented and discussed from their metallurgical aspect. And the coating effect of various alloying elements(Au, Ag, Cu, Zn, Cr, Mn, etc.) to the Cu or 65-35 brass core on them was reviewed also. The removal rate of some coated wires are higher than that of 65-35 brass electrode wire because the wire is difficult to break due to the wire cooling effect of Zn evaporation latent heat and the Zn oxide on the surface is effective in preventing short circuit. The removal rate increases with increasing Zn content from 35, 40 and Zn coated wire

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.687-691
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• 2000

Diamond turning machines for manufacture of precision optics require deliberate diagnosis to ensure that all the machine elements are properly operating, kinematically, dynamically and thermally, to produce demanded work qualities. One effective way is to directly inspect topographical features of work surfaces that have been carefully generated with prescribed machining conditions intended to exaggerate faulty consequences of any ill-operating machine elements. In this research, a very-large-scale Phase measuring interferometric system that has been developed for years at Korea Advanced Institute of Science and Technology is used to fulfill the metrological requirements fur the surface analysis. A special stitching technique is used to extend the measuring range, which integrates all the patches that are separately sampled over the whole surface while moving the stage. Then, the measured surface profile is analyzed to releated the machine error sources. For this, zernike polynomial fitting is used together with the wavelet filter and the fourier transform. Experimental results showed that the suggested technique in this study is very effective in diagnosing actual diamond turning machines

• 반도체디스플레이기술학회지
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• 제5권3호
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• pp.5-10
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• 2006

This paper investigates cutting qualities after laser dicing and predicts the problems that can be generated by laser dicing. And through 3 point bending test, die strength is measured and the die strength after laser dicing is compared with the die strength after mechanical sawing. Laser dicing is chiefly considered as an alternative to overcome the defects of mechanical sawing such as chipping on the surface and crack on the back side. Laser micromachining is based on the thermal ablation and evaporation mechanism. As a result of laser dicing experiments, debris on the surface of wafer is observed. To eliminate the debris and protect the surface, an experiment is done using a water soluble coating material and ultrasonic. The consequence is that most of debris is removed. But there are some residues around the cutting line. Unlike mechanical sawing, chipping on the surface and crack on the back side is not observed. The cross section of cutting line by laser dicing is rough as compared with that by mechanical sawing. But micro crack can not be seen. Micro crack reduces die strength. To measure this, 3 point bending test is done. The die strength after laser dicing decreases to a half of the die strength after mechanical sawing. This means that die cracking during package assembly can occur.

• 생물환경조절학회지
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• 제9권2호
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• pp.94-100
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• 2000

자극 종류(광질, 촛불, 바람, 수온)에 따른 식물의 엽표면 전위 포텐셜의 변화가 조사되었다. 광자극시 광질 및 점.멸간격(5초, 15초, 30초)에 따른 전위포텐셜의 변화는 다르게 나타났으며, 동일한 자극일지라도 아침, 점심, 저녁시간에 따라 그 반응이 달랐다. 또한, 촛불대기, 바람, 5$^{\circ}C$의 저온수 분무 등의 자극도 엽표면 전위포텐셜의 변화를 발생시켰으며, 식물에 따라 반응 패턴이 서로 다르게 나타났다. 결국 같은 자극일지라도 식물종에 따라 엽표면 전위포텐셜의 변화가 다르게 나타났으며, 동일한 식물일지라도 자극의 종류에 따라 서로 다른 반응패턴을 보였다. 한편, 전위포텐셜의 주파수 분석에 따르면, 대부분의 자극에 대해서 10Hz 대역이 다른 주파수 대역보다 높은 값을 나타내었다.