• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.525-528
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• 2006

This paper considers the vehicle dispatching problem in the automated material handling system (AMHS) of a large scale semiconductor fabrication line, which consists of 18 bays, 468 equipments and uses more than 130 overhead hoist transporters (OHT). We propose an assignment problem based vehicle dispatching approach to take advantage of simultaneous vehicle reassignment based on up-to-date system status. The proposed approach compares fsvorably with the shortest travel distance first rule and with the reassignment based rule which was recently proposed by the authors, in the number of vehicles required and the average lead time.

• 제어로봇시스템학회논문지
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• 제15권12호
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• pp.1240-1245
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• 2009

The throughput characteristics of the cluster tool with dual blade robot are analyzed. Using equipment's cycle time chart of the equipment, simple analytic form of the throughput is derived. Then, several important throughput characteristics are analyzed by the throughput formula. First, utilization of the process chamber and the robot are maximized by assigning the equipment to the process whose processing time is near the critical process time. Second, rule for selecting optimal number of process chambers is suggested. It is desirable to select a single process chamber plus a single robot structure for relatively short time process and multi process chambers plus a single robot, namely cluster tool for relatively long time process. Third, throughput variation between equipments due to the wafer transfer time variation is analyzed, especially for the process whose processing time is less than critical process time. And the throughput and the wafer transfer time of the equipments in our fabrication line are measured and compared to the analysis.

• Preventive Nutrition and Food Science
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• 제2권4호
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• pp.285-290
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• 1997

Previously, a 50% aqueous methanol extract of Galla rhois was shown to be the most potent tyrosinase inhibition activity with an {TEX}$IC_{50}${/TEX}(the concentration causing 50% inhibition of tyrosinase activity) of 0.2mg/ml of 205 crude drug extracts. To isolate tyrosinase inhibitors, the methanol extract was evaporated to a small volume in vacuo, and then partitioned stepwise with benzene and ethyl acetate(EtOAc). the EtOAc fraction was solubilized in 10% MeOH solution, and then fractionated successively by Diaion HP-20 and Sephadex LH-20 column chromatography, and preparative HPLC. Three phenolic compounds were isolated, and characterized as gallic acid(GA), methyl gallate(MG) and 1,2,3,4,6-penta-O-galloyl-$\beta$-D-glucose(PGG) by UV, IR, {TEX}${1}^H${/TEX}-&{TEX}${13}^C${/TEX}-NMR, and FAB-MS spectroscopy, PGG({TEX}$IC_{50}${/TEX}=50$\mu\textrm{g}$/ml) showed a considerable inhibitory effect against mushroom tyrosinase, while GA({TEX}$IC_{50}${/TEX}=1.6mg/ml) and MG({TEX}$IC_{50}${/TEX}=234$\mu\textrm{g}$/ml) did not show an appreciable effect. Meanwhile, MG inhibited greatly melanogenesis in a murine melanocyte cell line, Mel-Ab. MG and PGG showed typical noncompetitive inhibition patterns against mushroom tyrosinase. These results suggest that PGG and MG may be potentially useful as either anti-browning or anti-melanogenic agents in foods and cosmetics.

• 한국식품영양과학회지
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• 제30권4호
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• pp.732-738
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• 2001

두충잎에서 인간대장암에세포 HCT-116에 세포증식 억제효과를 나타내는 성분을 silica gel column chromatography TLC로 분리하고 HPLC로 정제한 다음 UV-visual spectro-photometer에 의한 흡수 spectra 특성 HPLC에 의한 retention time과 분리패턴 및 FAB/MS로 분자량을 잠정적으로 동정한 결과 TLC 상에서 분리된 Rf 0.19 band 의 화합물은 chlorophyll a에서 $Mg^{2+}$이 제거된 pheophytin a로 Rf 0.25 band의 화합물은 pyropheophytin a로 확인되었다. 동정된 화합물들의 암세포 억제작용을 확인하기 위해 두충잎의 petroleum ether extract column chromatography로 분리한 분획물 및 TLC에서 분리된 각 band들의 cytotoxic activity을 in vitro에서 HCT-116 cancer cell을 사용하여 측정한 결과 모든 시료에서 암세포 증식억제 현상을 보였으며 특히 Rf 0.19와 Rf 0.25 band에서 분리된 화합물들에서 강하게 나타났다. 이 결과로 볼 때 두충잎에서 분리한 클로로필 유도체는 인간대장암세포인 HCT-116 cell에 대해 강한 항암작용이 있는 것으로 생각된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.464-464
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• 2010

A few years ago, for maintaining high stability and production yield of production equipment in a semiconductor fab, on-line monitoring of wafers is required, so that semiconductor manufacturers are investigating a software based process controlling scheme known as virtual metrology (VM). As semiconductor technology develops, the cost of fabrication tool/facility has reached its budget limit, and reducing metrology cost can obviously help to keep semiconductor manufacturing cost. By virtue of prediction, VM enables wafer-level control (or even down to site level), reduces within-lot variability, and increases process capability, $C_{pk}$. In this research, we have practiced VM on $SiO_2$ etch rate with optical emission spectroscopy(OES) data acquired in-situ while the process parameters are simultaneously correlated. To build process model of $SiO_2$ via, we first performed a series of etch runs according to the statistically designed experiment, called design of experiments (DOE). OES data are automatically logged with etch rate, and some OES spectra that correlated with $SiO_2$ etch rate is selected. Once the feature of OES data is selected, the preprocessed OES spectra is then used for in-situ sensor based VM modeling. ICP-RIE using 葰.56MHz, manufactured by Plasmart, Ltd. is employed in this experiment, and single fiber-optic attached for in-situ OES data acquisition. Before applying statistical feature selection, empirical feature selection of OES data is initially performed in order not to fall in a statistical misleading, which causes from random noise or large variation of insignificantly correlated responses with process itself. The accuracy of the proposed VM is still need to be developed in order to successfully replace the existing metrology, but it is no doubt that VM can support engineering decision of "go or not go" in the consecutive processing step.