• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
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• pp.59-62
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• 1999

• 한국자동차공학회논문집
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• 제3권3호
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• pp.79-89
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• 1995

Rattle noise occurs at manual transmission as idling and driving of a automotive. It can be solved by torsional characteristics of a clutch disc. A clutch disc consist of a region of pre-damper and main-damper. Rattle noise is affected by pre-damper and main-damper equipped for a torsional spring and friction washer. Pre-damper range covers noise radiating from manual transmission when engine is idling and main-damper range covers noise when engine is driving. The aim of this reserch is to clear transmission rattle noise by way of torsional characteristics of a clutch disc. The experiment is carried out as idling and driving of a automobile equipped for 1.5L MPI engine, dry single-disc type clutch and manual transmission. In this study, the results show for a vibration of manual transmission as idling and driving can be cleared by a clutch disc of Pre-damper type.

• Journal of Korean Neurosurgical Society
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• 제39권6호
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• pp.432-437
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• 2006

Objective : In order to establish the index of degeneration, the authors performed a histochemical study with Safranin-O staining and investigated the occurrence of apoptosis in the human intervertebral disc. Methods : Eighteen intervertebral disc specimens surgically extracted from the patients and two additional specimens from the autopsied cases were stained with Safranin-O for proteoglycan according to a standard protocol. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate- biotin nick end labeling[TUNEL] was used to detect the fragmented DNA known to be associated with apoptotic cell death and classification scheme was formulated for categorization of the degree of Safranin-O staining [normal, moderate reduction, faint] by modification of Makin's histological-histochemical grading. The Kruskal-Wallis H test and Chi-square test were used for statistical analysis. Results : The statistical results showed a significant difference in the mean age between "normal" Safranin-O staining group and the others [19.3 versus 55, 43.4, p=0021]. However, there was no statistically significant correlation between Safranin-O staining and MR grading of disc degeneration. Only six of eighteen surgical specimens and none in autopsies showed positive apoptotic cells in TUNEL staining. Conclusion : The determination of the degree of degeneration in surgically obtained disc tissue per se by histochemical staining or by the degree of apoptosis that corresponds to its morphologic change was not feasible.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.258-265
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• 2000

This study is to develop a Fe-based disc brake tinning with sponge structure for passenger car of 150km/h train and to concept design with 3 groove type for brake disc reducing hot hair-crack and certainly friction coeifficient. The developping brake linning would be to presumption of thermal stress Max.5.53k9/m0 of the 3 groove type. and It is stable friction coeifficient and wear rate on the Full Scale Brake dynamometer. So 3 groove type must be reduced to hot stress between Brake disc and Linning and Friction temperature is reduced about 20$^{\circ}C$

• 한국식품조리과학회지
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• 제27권4호
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• pp.17-26
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• 2011

본 연구는 지유 에탄올 추출물의 항균 및 항돌연변이 활성을 측정하여 새로운 기능성 소재로서의 기초자료를 얻고자 실시하였다. E. coli, E. coli O157:H7, P. aeruginosa, S. Typhimurium, L. monocytogenes, B. cereus, S. aureus의 7가지 주요 식품위해성 세균에 대한 항균활성을 검증하기 위해 paper disc diffusion assay 및 최소저해농도를 측정하였으며 24시간 동안 균의 생육억제도를 측정하였다. Paper disc assay 결과 E. coli와 E. coli O157:H7을 제외한 5가지 균에 대한 지유 에탄올 추출물의 뚜렷한 clear zone이 확인되었다. Micro-well dilution법으로 확인한 최소저해농도의 범위는 E. coli와 E. coli O157:H7을 제외한 5가지 균에 대해서 0.625~2.5 mg/mL로 나타났으며 생육억제도 실험결과도 최소 저해농도 결과와 일치하였다. Salmonella Typhimurium TA100을 이용한 Ames test 결과, 5 mg/plate의 농도에서 직접 돌연변이원인 sodium azide와 4-NQO에 대한 지유 에탄올 추출물의 항돌연변이 활성이 각각 72.42와 89.85%로 나타나 지유 에탄올 추출물의 우수한 항돌연변이 활성을 확인하였다. 본 연구를 통해 지유 에탄올 추출물이 주요 식품위해성 세균들에 대한 우수한 항균성과 직접돌연변이원에 대한 높은 항돌연변이 활성을 나타내어 천연물 유래 생리활성 소재로 이용될 수 있는 가능성을 보여주었다.

• Tribology and Lubricants
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• 제30권1호
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• pp.29-35
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• 2014

The temperature-dependent tribological properties of brake discs for a train were examined in this study. The discs were produced using heat-resistant alloy steel, which showed different thermal conductivity after the heat treatments. A commercial brake friction material was used to evaluate the friction effectiveness, and the friction tests were carried out using a 1/5 scale dynamometer under various initial braking temperature conditions. The results showed that the tribological property of the disc was strongly affected by the heat treatment schedule. At low temperatures (below $250^{\circ}C$), the friction coefficient increased as a function of disc temperature, indicating that frictional heat increased the adhesion between the disc and pad. In addition, fade was observed at high temperatures (above $250^{\circ}C$); it was pronounced in the case of the disc with low thermal conductivity. The different fade resistances observed in the discs with different heat treatment schedules appear to be influenced by microstructural changes such as carbide redistribution occurring during the heat treatments, which affected the thermal conductivity.

• 생명과학회지
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• 제7권2호
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• pp.112-118
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• 1997

Gallic acid로부터 pyrogallol로 전환하는 균주를 토양에서 분리 동정하여 얻는 Pseudomonas sp. KS-96의 균체를 회전원판 반응조에 고정화시킨 후 연속전환을 시도하여 다음과 같은 결과를 얻었다. Gallate decarboxylase의 활성은 배양 24시간에서 가장 좋았다. 반응조의 원판에 gallic acid가 함유된 액체 배양액을 시간당 20m${\ell}$씩 공급하면서 균체막의 두께가 steady state에 도달할때까지 공급하였다. 균체를 고정화 시킨 후 시간 경과에 따른 전환율은 18시간부터 36시간에서 전환율이 높았다. 균체 고정화 후에 gallic acid를 15g/${\ell}$ 함유하는 기질을 시간당 30m${\ell}$씩 주입했을 때 pyrogallol의 전환율이 가장 좋았으며 회전원판 반응조에 의한 연속적 전환은 6일에서 8일까지가 각각 81%, 80%로서 가장 높았다.

• Tribology and Lubricants
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• 제30권3호
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• pp.177-182
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• 2014

To stop a high speed train running at the speed of 300 km/h, the disc brake for the train should be able to dissipate enormous kinetic energy of the train into frictional heat energy. Sintered pin-type metals are mostly used for friction materials of high speed brake pads. A pad comprises several friction pins, and the topology, length, flexibility, composition, etc. have a great influence on the tribological properties of the disc brake. In this study, the topology of the friction pins in a pad was our main concern. We presented the optimization of the topology of a railcar brake pad with nine-pin-type friction materials by thermo-mechanical contact analysis. We modeled the brake pad with/without a back plate. To simulate a continuous braking, the pad or friction materials were rotated at constant velocity on the friction surface of the disc. We varied the positions of the nine friction materials to compare the temperature distributions on the disc surface. In a non-optimized brake pad, the distance between two neighboring friction materials in the radial direction from the rotational center of the disc was not equal. In an optimized pad, the distance between two neighboring friction materials in the radial direction was equal. The temperature distribution on the disc surface fluctuated more for the former than the latter. Optimizing the pad reduced the maximum temperature of the brake disc by more than 10%.

• Korean Journal of Mathematics
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• 제27권4호
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• pp.1027-1041
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• 2019

In this paper, we present a Schwarz lemma at the boundary for analytic functions at the unit disc, which generalizes classical Schwarz lemma for bounded analytic functions. For new inequalities, the results of Jack's lemma and Hankel determinant were used. We will get a sharp upper bound for Hankel determinant H₂(1). Also, in a class of analytic functions on the unit disc, assuming the existence of angular limit on the boundary point, the estimations below of the modulus of angular derivative have been obtained.

• 한국식품조리과학회지
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• 제28권1호
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• pp.9-15
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• 2012

This study analyzed the antibacterial activity of a Rubus coreanum (Bokbunja) ethanol extract. The antimicrobial activity was determined by disc diffusion, minimum inhibitory concentration (MIC), and growth inhibition methods with seven kinds of bacteria related to foodborne illness (Bacillus cereus, Escherichia coli, Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhimurium). In the results, disc diffusions of the ethanol extract from R. coreanum (9.8-17.5 mm at $4,000{\mu}g/disc$) clearly showed the antimicrobial activity of the extract against all tested microorganisms. Rubus coreanum promoted an inhibitory effect as follows: E. coli O157:H7 > P. aeruginosa > L. monocytogenes > E. coli > S. aureus > B. cereus ${\geq}$ S. typhimurium. In the MIC test, R. coreanum showed high antimicrobial effect against L. monocytogenes at 500 ppm. Moreover, the R. coreanum ethanol extract showed strong growth inhibition against microorganisms, similar to the MIC results. These results show that a R. coreanum ethanol extract has powerful antimicrobial activity against all tested microorganisms, suggesting that R. coreanum will be useful as a potential natural preservative.