• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.42-42
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• 2000

진공장비 내에서 사용되는 베어링에 있어서 그리이스나 오일은 중기압이 높아 장치내 진공도 저하뿐 아니라 처리되는 부품에 오염을 초래하게 되므로 많은 경우 진공 환경용 베어링은 전동면 또는 마찰면에 마찰계수가 매우 낮은 박막을 형성시켜 윤활을 실현한다. 진공용 베어링이 사용되는 곳은 인공위성의 안테나, 태양전지 전개 기구 및 회전부 등 우주항공 분야를 비롯하여, 상업적으로는 X-ray 발생장치, 반도체 등 전자소재 제조 장치의 구동부 및 각종 진공 증착 장치 등에 널리 사용되고 있다. 이러한 진공용 베어링은 일반 베어링의 수 천배에 달하는 고가로 그간 전량 수입에 의존하여 왔으며 근래에는 국내 전자 산업의 발전과 더불어 그 수요가 폭발적으로 증가하여 수입 비용의 부담도 크게 늘고 있다. 당사에서는 진공에서의 각종 요구특성에 대응한 베어링으로 연질금속계(Ag. Au, Pb) 황하물계(Mos2), 폴리머계(PTFE) 의 윤활 막을 코팅한 진공용 베어링을 개발하여 공급능력을 갖추었기에 이의 특징 및 용도를 소개하고자 한다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.179-185
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• 2001

High performance characteristics are required for rolling bearings and the various functions of bearing are greatly influenced by grease. Recently, higher performance is being demanded of rolling bearing greases for bearing lubrication. Four special greases with different composition such as lithium soap/ester oil, urea/ester oil, urea/ether oil and PTFE/fluorine oil were synthesized to compare the performance of these greases with that of the conventional lithium soap/mineral oil grease. The grease properties were investigated using a series of typical grease testing methods and grease life test. After the life test, the greases were charaterized by FTIR analysis and a microscope. And the iron amount in the greases was analyzed by AAS after ashing. The composition and manufacturing process determined the grease performance. The grease with a base oil of synthetic oil showed higher performance and the urea/ester oil and PTFE/fluorine oil showed about three times longer life as compared with conventional lithium grease.

• Annual Conference on Human and Language Technology
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• 1993.10a
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• pp.111-117
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• 1993

강세간 음절이 증가되는데 따른 시간의 증가비율을 알아보기 위해 남녀 및 연령으로 구분되는 4그룹을 선정하여, 증가되는 음절의 마지막 낱말이 각각 '이(V)', '도(CV)', '썽(CVC)'으로 구분되는 자료를 이용하였다. 결과적으로 나온 한국어의 강세간 음절증가에 따른 시간의 증가비율의 모습은 젊은층에서는 음절시간언어에 가까운 모습을 나타내며 이에 반해 장년층은 강세시간언어의 모습을 보여준다. 두 그룹을 하나로 통합한 결과는 음절시간언어와 강세시간 언어의 중간적 양상 즉 그리이스어와 가까운 모습으로 나타난다.

• The Korean Journal of Zoology
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• v.24 no.2
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• pp.117-121
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• 1981

우리나라 현실을 알기 위해서는 分類學의 歷史的 背景을 살필 필요가 있다. 그 역사를 Darwin 以前과 Darwin 以後로 크게 區分할 수 있다. Darwin 이전의 대표자로서 그리이스의 Aristoteles와 18세기의 Linne를 들 수 있는데 Linne는 種名의 二名法의 확립과 카테고리의 설정으로써 分類學의 發展에 크게 공헌하였고, 그의 哲學的 背景은 Aristoteles의 사상과 통하는 스콜라 哲學이었다. 그의 種의 槪念은 靜的인 것이었고, 그는 少數의 識別形質만을 重要視하였다. Darwin 이후에는 進化思想이 分類學에 절대적인 영향을 주어 학자들은 動物의 系統探求에 熱을 올리게 되었고, 種의 개념은 動的인 경우로 되었다. 또한 Linne 이후에는 動物의 新種記載가 급증하였다. 20세기에 들어와서는 自然系統分類學 生物學的 系統分類學, 數理分類學 (numerical taxonomy, 二次大戰 이후), 生化學的 技術의 도입 등 分類學에 새로운 면이 첨가되면서 種의 개념을 변천하고 種의 定義는 多樣化하였으며, 分類學上의 形質과 系統發生 究明方法이 확장되었다.

• Journal of the Korean Society of Tobacco Science
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• v.9 no.1
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• pp.11-17
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• 1987

KA 101 and Xanthi-Basma were cultivated in Korea and Greece to compare the respective responses to environment and cultivation method on their growth characteristics and some properties of harvested leaves during 1984 and 1985. The contents of clay, calcium, organic matter and pH were higher in the soil of greece than that of Korea. Sunshine hours and precipitation in Greece during harvest and curing season were 8.6 hours per day and 53.3mm compared to that of 3.8 hours per day and 320mm in Korea, respectively. The plant height, leaf size and yield decreased, and days to flower was shorter 8-11 days in greek grown plants. The dehydration and curing process in Greece was linear and rapid due to the constant daily change of temperature and relative humidity with dry weather during curing season during curing season. But those process in Korea was variable and tardy due to rainy weather. Cured leaf ratio increased with upper stalk leaves in Greece but it was rather lower at top stalk position in Korea. The harvested green leaf cultivated in Greece showed higher contents of petroleum ether extract, total nitrogen and nicotine, but lower contents of reducing sugar and lower ratio of protein nitrogen to total nitrogen than in Korea.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.99-105
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• 2000

Greases composed of base oil and thickener are widely used in the purpose of lubrication and anti-corrosion of machinery. However, greases are sometimes oxidized and decomposed by heat of friction, and produced organic acid. And the greases leaked out ordinary spot make the concrete structures weaken. In this study, the chemical effects of the greases with the concrete structures were investigated through oxidation reaction under pressure and oxygen, and evaluated by the analysis of TAN, Ca content, FT-IR and XRD of grease and cement powder after the oxidation reaction. As the results, TAN value decreased with the increase of the content of cement because of neutralization of organic acid produced by the oxidation of grease with calcium contained in the cement. The content of calcium linearly increased with the increase of cement due to calcium salt by neutralization of acid. Also, according to XRD results of the cement powder oxidized at 99 $^{\circ}C$, the diffraction peak due to calcium hydroxide decreased in comparison with that at room temperature because of the reaction of calcium and organic acid.

• Tribology and Lubricants
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• v.22 no.5
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• pp.269-275
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• 2006

Rolling bearings are classified one of the most important machine elements. The various function of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve bearing lubrication. Three urea/ether oil greases with different composition were synthesized to compare the performance of these greases. The typical grease physical properties were investigated, and life test of these greases was conducted by FE-9 grease life tester. The grease with higher content of the thickener showed higher performance. After these preliminary test, twelve greases were synthesized and evaluated the performance of dropping point and OIT value. And optimized conditions for grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) using dropping point and OIT value respectively. The optimized grease using OIT value showed longer grease life than that using dropping point. Two greases were synthesized following the optimum synthesis conditions by means of OIT value. Then grease life and other properties of these greases were investigated. These two greasaes showed longer grease life than typical urea/ether oil grease.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.123-129
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• 2004

Rolling bearings are assorted one of the most important machine elements. The various functions of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve rolling bearing lubrication. The two conditions for optimum grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) program by using dropping points and OIT values respectively. And the optimized two urea/ether oil greases were synthesized to compare the performance. The typical physical properties of grease were investigated. And life test of these greases was conducted by rolling bearing grease life tester The characteristics of the greases before and after life test were investigated using FTIR, microscope, SEM, TG/DSC, OIT and TAN meter The optimized two greases showed longer life time than typical urea/ether oil grease. The optimized grease by means of OIT value showed higher performance such as long life time. low TAN value and high oil bleeding amount in comparison with the optimized grease using dropping point.

• Tribology and Lubricants
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• v.21 no.1
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• pp.21-26
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• 2005

Rolling bearings are assorted one of the most important machine elements. The various functions of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve rolling bearing lubrication. The two conditions for optimum grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) program by using dropping points and OIT values respectively. And the optimized two urea/ether oil greases were synthesized to compare the performance. The typical physical properties of grease were investigated. And life test of these greases was conducted by rolling bearing grease life tester. The characteristics of the greases before and after life test were investigated using FTIR, microscope, SEM, TG/DSC, OIT and TAN meter. The optimized two greases showed longer life time than typical urea/ether oil grease. The optimized grease by means of OIT value showed higher performance such as long life time, low TAN value and high oil bleeding amount in comparison with the optimized grease using dropping point.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.129-138
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• 2003

Rolling bearings are classified one of the most important machine elements. The various function of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required in improve bearing lubrication. Three urea/ether oil greases with identical composition were synthesized to compare the performance of these greases according to the thickener content of grease. The typical grease physical properties were investigated. And life test of these greases was conducted by FE-9 grease life tester. The characteristics of the greases before and after life test were investigated using FT-IR, microscope, OIT and TAN meter. Large differences in the grease performance depending on the content of the thickener were observed. The grease with higher content of the hickener showed higher performance such as long life time and low TAN value. After preliminary test, twelve greases were synthesized and evaluated the performance of dropping point and OIT, then optimized two greases were selected by SSRED (Six Sigma Robust Engineering Design) using dropping point and OIT data. Characteristics of the optimized two greases were on the same level with estimated value. The optimized grease by means of OIT value showed longer grease life in comparison with optimized grease by dropping point. However two greases showed higher performance than typical urea/ether oil.