• Korean Journal of Materials Research
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• v.19 no.8
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• pp.421-426
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• 2009

We report on the capacitively coupled O2 plasma etching of PMMA and polycarbonate (PC) with a diffusion pump. Plasma process variables were process pressure and CCP power at 5 sccm $O_2$ gas flow rate. Characterization was done in order to analyze etch rate, etch selectivity, surface roughness, and morphology using stylus surface profilometry and scanning electron microscopy. Self bias decreased with increase of process pressure in the range of 25$\sim$180 mTorr. We found an important result for optimum pressure for the highest etch rate of PMMA and PC, which was 60 mTorr. PMMA and PC had etch rates of 0.46 and 0.28 ${\mu}m$/min under pressure conditions, respectively. More specifically, etch rates of the materials increased when the pressure changed from 25 mTorr to 60 mTorr. However, they reduced when the pressure increased further after 60 mTorr. RMS roughnesses of the etched surfaces were in the range of 2.2$\sim$2.9 nm. Etch selectivity of PMMA to a photoresist was $\sim$1.5:1 and that of PC was $\sim$0.9:1. Etch rate constant was about 0.04 ${\mu}m$/minW and 0.02 ${\mu}m$/minW for PMMA and PC, respectively, with the CCP power change at 5 sccm $O_2$ and 40 mTorr process pressure. PC had more erosion on the etched sidewall than PMMA did. The OES data showed that the intensity of the oxygen atomic peak (777.196 nm) proportionally increased with the CCP power.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.12
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• pp.1753-1757
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• 2012

A new liquid chromatographic tandem mass spectrometric (LC-MS/MS) assay for the quantification of ginsenoside Rb1 in human plasma was developed and validated. The separation was performed on a Agilent C18 column ($4.6mm{\times}150mm$, particle size 5 ${\mu}m$) with a gradient elution of 0.1% formic acid in water and 0.1% formic acid in methanol and a flow rate of 0.9 mL/min. The analyte was determined using electrospray positive ionization mass spectrometry in the multiple reaction monitoring (MRM) mode (m/z 1131.714${\rightarrow}$365.303). Human plasma samples were extracted with acetone : water (50:50) by the liquid-liquid extraction method. The method was linear over the dynamic range of 10~500 ng/mL with a correlation coefficient of r=0.9995. The intra-and inter-day precision over the concentration range of ginsenoside Rb1 was lower than 5.8% (correlation of variance, CV), and the accuracy was between 96.0~104.6%. This LC-MS/MS assay of ginsenoside Rb1 in human plasma is applicable for quantification in a pharmacokinetic study.

• The Korean Journal of Physiology
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• v.21 no.2
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• pp.211-223
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• 1987

Head-down tilt (HDT) at $-6^{\circ}$ has been commonly used as the experimental model in both man and animals to induce the blood shift toward the head or central protion of the body, demonstrating similar physiological effect encountered in the weightlessness in the orbital flight. There are few reports about the physiological response upon the cardiovascular regulatory system or the tolerance to the $(-6^{\circ})$ HDT within a relatively short period less than 1 hour. Therefore, the purpose of this study way to observe the effects of $-6^{\circ}$ HDT on cardiovascular system within 30 minutes and to evaluate early regulatory mechanism for simulated hypogravity. Ten mongrel dogs weighing 8-12 kg were anesthetized with the infusion of 1% ${\alpha}-chloralose$ (100 mg/kg) intravenously, and the postural changes were performed from the supine to the $-6^{\circ}$ head-down Position, then from the head-down to the supine (SUP), and each posture was maintained for 30 minutes. Blood flow $({\dot{Q}})$ through common carotid and femoral arteries were determined by the electromagnetic flowmeter. Mean arterial pressure (MAP), heart rate (HR), respiratory rate , and pH, $P_{O_2}$, $P_{CO_2}$ and hematocrit (Hct) of arterial and venous blood were also measured. The peripheral vascular resistance was calculated by dividing respective MAP values by ${\dot{Q}}$ through both sides of common carotid or femoral arteries. The concentration of plasma epinephrine and norepinephrine was determined by Peuler & Johnson's radioenzymatic method. The results are summarized as follows: In the initial 5 minutes in $-6^{\circ}$ HDT, HR was significantly (p<0.05) increased and MAP slightly decreased. Although ${\dot{Q}}$ and carotid peripheral artery resistance were not significantly changed, ${\dot{Q}}$ through femoral artery was diminished and femoral peripheral artery resistance was elevated. In the SUP, the initial changes of MAP and HR were increased (p<0.05), but those of ${\dot{Q}}$ and peripheral vascular resistance through both common carotid and femoral arteries were not significant. After 10 minutes of each postural change in both HDT and SUP, MAP was maintained almost equal to that of the level of pretilting control. During 60 minutes of both postural changes of HDT and SUP, $P_{O_2}$ and Hct were not changed significantly. However pH tended to increase slowly and $P_{CO_2}$ was gradually decreased. The pH and $P_{CO_2}$ seemed to be related to the increased respiratory rate. Plasma epinephrine concentration was not changed significantly and plasma norepinephrine concentration was slightly decreased in the course of HDT and also at 10 minutes of SUP. However these concentration changes were statistically insignificant. From these results, it may be concluded that the effect of $-6^{\circ}$ HDT for 30 minutes on the cardiovascular system and plasma catecholamine levels of the dog is minimum and it is suggestive that the cardiovascular regulatory mechanism, possibly mediated by so called gravity receptors including baroreceptor and volume receptor, has been properly and adequately operated.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.229-237
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• 2003

The purpose of this study was to compare the effect of exposure time on the polymerization of surface and 2 mm below the surface of light-cured restorative materials cured with three different light sources; conventional halogen light curing unit(XL 3000, 3M, U.S.A.), plasma arc light curing unit(Flipo, LOKKI, France) and light emitting diode(LED) light curing unit(Elipar Free light, 3M, U.S.A.) and compare the uniformity of polymerization from the center to the periphery of resin surfaces according to polymerization diameter cure with three different light sources. From the experiment, the following results were obtained. 1. In Z-100, Plasma arc light exposure time of 6 to 9 seconds and LED light exposure time of 40 to 60 seconds produced microhardness values similar to those produced with 40 second exposure to a conventional halogen light(p>0.05). 2. In Tetric Flow, Plasma arc light exposure time of 9 seconds and LED light exposure time of 40 to 60 seconds produced microhardness values similar to those produced with 40 second exposure to a conventional halogen light(p>0.05). 3. In Dyract AP, Plasma arc light exposure time of 6 to 9 seconds and LED light exposure time of 20 to 40 seconds produced microhardness values similar to those produced with 40second exposure to a conventional halogen light(p>0.05). 4. In Fuji II LC, Plasma arc light exposure time of 9 seconds and LED light exposure time of 20 to 60 seconds produced microhardness values similar to those produced with 40second exposure to a conventional halogen light(p>0.05). 5. Except Fuji II LC, microhardness was decreased from the center to the periphery in all light sources(p<0.05).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.250-251
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• 2009

For the fabrication of a multilevel resist (MLR) based on a very thin amorphous carbon (a-C) layer an $Si_{3}N_{4}$ hard-mask layer, the selective etching of the $Si_{3}N_{4}$ layer using physical-vapor-deposited (PVD) a-C mask was investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in $CH_{2}F_{2}/H_{2}/Ar$ plasmas : HF/LF powr ratio ($P_{HF}/P_{LF}$), and $CH_{2}F_{2}$ and $H_2$ flow rates. It was found that infinitely high etch selectivities of the $Si_{3}N_{4}$ layers to the PVD a-C on both the blanket and patterned wafers could be obtained for certain gas flow conditions. The $H_2$ and $CH_{2}F_{2}$ flow ratio was found to play a critical role in determining the process window for infinite $Si_{3}N_{4}$/PVDa-C etch selectivity, due to the change in the degree of polymerization. Etching of ArF PR/BARC/$SiO_x$/PVDa-C/$Si_{3}N_{4}$ MLR structure supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the $Si_{3}N_{4}$ layer.

• Journal of the Semiconductor & Display Technology
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• v.8 no.3
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• pp.19-23
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• 2009

We have studied dielectric characteristics of low-k interlayer dielectric materials was fabricated by plasma enhanced chemical vapor deposition (PECVD). BTMSM precursor was introduced with the flow rates from 24 sccm to 32 sccm by 2 sccm step in the constant flow rate of 60 sccm $O_2$. Then, SiOCH thin film deposited at room temperature was annealed at temperature of $400^{\circ}C$ and $500^{\circ}C$ for 30 minutes in vacuum. The vibrational groups of SiOCH thin films were analyzed by FT/IR absorption lines, and the dielectric constant of the low-k SiOCH thin films were obtained by measuring C-V characteristic curves. With the result that FTIR analysis, as BTMSM flow rate increase, relative carbon content of SiOCH thin film increased from 29.5% to 32.2%, and increased by 32.8% in 26 sccm specimen after $500^{\circ}C$ annealing. Dielectric constant was lowest by 2.32 in 26 sccm specimen, and decreased more by 2.05 after $500^{\circ}C$ annealing. Also, leakage current is lowest by $8.7{\times}10^{-9}A/cm^2$ in this specimen. In the result, shift phenomenon of chemical bond appeared in SiOCH thin film that BTMSM flow rate is deposited by 26 sccms, and relative carbon content was highest in this specimen and dielectric constant also was lowest value

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.423-429
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• 2009

The purpose of this study is to investigate the optimal condition for the hydrogen-rich gas production and the CO removal by reforming of gliding arc plasma reforming system using biogas. The parametric screening studies were carried out according to changes of steam feed amount, catalyst bed temperature in water gas reactor and catalyst bed temperature, input air flow rate in preferential oxidation reactor. The standard condition is as follows. The steam/carbon ratio, catalyst bed temperature, total gas flow rate, input electric power and biogas composition rate ($CH_4$ : $CO_2$) were fixed 3, $700^{\circ}C$, 16 L/min, 2.4 kW and 6 : 4, respectively. The results are as follow, HTS optimum operating conditions were S/C ratio of 3 and reactor temperature of $500^{\circ}C$. LTS were S/C ratio of 2.9 and temperature of $300^{\circ}C$. Also, PROX I optimum conditions were input air flow rate of 300 mL/min and reactor temperature of $190^{\circ}C$. PROX II were 200 mL/min and $190^{\circ}C$ respectively. After having passed through each reactor, the results were as follows: 55% of $H_{2}$ yield, 0% of CO selectivity, 99% of $CH_4$ conversion rate, 27% of $CO_2$ conversion rate, respectively.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.317-340
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• 1993

This study was designed 1) to compare the distributions of periapical inflammatory cells and 2) to identify lymphocytes and compare the lymphocyte distribution with T lymphocyte subpopulation and then 3) to examine the distribution of cycling cell in human dental periapical lesions. From each of the twenty-five human dental periapical lesions observed one small portion was fixed, embeded in paraffin, sectioned serially and stained with HE. The periapical inflammatory cells were counted to obtain the relative concentration of lymphocyte, plasma cell, macrophage and neutrophil. The large part of each lesion was analysed using Flow cytometer and monoclonal antibodies to obtain the relative concentration of T lymphocyte, B lymphocyte, T'helper cell and T suppressor/cytotoxic cell. In addition to that, seven human dental periapical lesions were examined with DNA analysis to observe the distribution of cycling cell. Following results were obtained: 1. 24 cases of the 32 periapical lesions examined were diagnosed as periapical granuloma and the remaining 8 cases as periapical cyst. Lymphocytes comprised 42.1% of total inflammatory cells in periapical granuloma and 41.8% in periapical cyst. Corresponding percentages for macrophages were 33.8% and 30.3%; for plasma cells, 15.9% and 19.0%; for neutrophils, 8.2% and 8.8%. 2. All of the periapical lesions examined had T lymphocyte, B lymphocyte, T helper cell, T suppressor/cytotoxic cell. And in all cases, T lymphocytes were observed predominantly more than B lymphocytes. 3. In 2 cases of the control group only T lymphocytes were found, and in the remaining 2 cases T lymphocytes were observed predominantly. 4. T helper cells were observed predominantly more than T suppressor/cytotoxic cells in all cases of perapical granulomas. 5. T suppressor/cytotoxic cells were observed predominantly more than T helper cells in 4 cases of periapical cysts (total 5 cases were examined) and only in one case T helper cells were more than T suppressor/cytotoxic cells. 6. In control group, T helper cells were predominant in 2 cases and T helper cells were equivalent to T suppressor/cytotoxic cells in one case. In remaining one case T suppressor/cytotoxic cells were predominant. 7. As the result of DNA analysis, the average proliferating indices of the various groups examined were measured as follows: in the control group 5.45%, in periapical granuloma 6.64%, in periapical cyst 10.1%. The highest index was observed in periapical cyst.

• Analytical Science and Technology
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• v.21 no.4
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• pp.316-325
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• 2008

An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with flow injection-hydride generation system was used for the determination of trace arsenic in seawater sample. The accuracy in this method was verified by the analysis of certified reference materials (CRM) of seawater (CASS-4, NASS-5). The analytical results agreed with certified value within the range of uncertainty. The expanded uncertainties for CASS-4 and NASS-5 in this experiment were ranged from 6.2% to 6.8% obtained from repeated analyses of the CRMs (n=5). The detection limit of $As^+$ (m/z=74.9216) in this method was confirmed about 0.01 ug/kg. Linearity obtained from calibration curve of arsenic was excellent ($R^2=1$). The detection at $As^+$ (m/z=74.9216) and $AsO^+$ (m/z=90.9165) by using oxygen reaction gas in DRC mode was compared. Sensitivity at $AsO^+$ (m/z=90.9165) was decreased about 25-fold, but the analytical results are the same that at $As^+$ (m/z=74.9216).

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.10
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• pp.1445-1452
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• 2002

The present experiment was carried out to study the utilization of substrates in the mammary gland of crossbred Holstein Friesian during feeding on different types of roughage. Sixteen pregnant crossbred Holstein heifers consisted of two breed types of eight animals each; Holstein Friesian${\times}$Red Sindhi (50:50=50%HF) and Holstein Friesian${\times}$Red Sindhi (87.5:12.5=87.5%HF). Animals were divided into four groups of the same breed type in each group which were fed with either rice straw treated with 5% urea or pangola hay (Digitaria decumbens) as the source of roughage throughout the experiments. Four consecutive experimental periods were carried out in late pregnancy (20-23 days before parturition), early lactation (30 days postpartum), mid-lactation (120 days postpartum) and late lactation (210 days postpartum). Measurement of mammary blood flow in combining with measurement of AV difference was performed for the mammary uptake of substrates. In the period of lactation, udder blood flow was nearly three times higher than that of late pregnant period (p<0.05) in both 50%HF and 87.5%HF feeding on either hay or urea treated rice straw. During mid- and late lactation of both groups of 87.5%HF animals, mammary blood flow and milk yield showed decrease when compared to those during the early lactating period while the trends for persistency were apparent in both groups of 50%HF animals throughout experimental periods. The mean arterial plasma concentrations of glucose, acetate, $\beta$-hydroxybutyrate and free glycerol in each group remained constant throughout experimental periods. During late pregnancy in all groups, the AV difference and extraction ratio of glucose, $\beta$-hydroxybutyrate and triacylglycerol across the mammary gland markedly lowered (p<0.05), which coincided with a lower net uptake by the mammary gland in comparison to the early lactating period. The mean arterial plasma concentration, AV difference and extraction ratio for acetate showed no significant differences between late pregnancy and the early lactating period. The AV difference of free glycerol showed apparent release from mammary tissue during late pregnancy in all groups. In mid- and late lactation, the mammary uptake for glucose, acetate and $\beta$-hydroxybutyrate in both groups of 87.5%HF animals showed apparent decrease as compared to that in the early lactating period, whereas no appearances were observed in 50%HF animals feeding either hay or urea treated rice straw. The mean arterial plasma concentrations for free fatty acid (FFA) and triacylglycerol (C16 to C18) were higher in late pregnancy than in early lactation in both types of crossbred animals. The values of AV difference and the net uptake by the mammary gland for FFA were variable during late pregnancy and lactating periods in all groups. There were no significant differences for AV difference, extraction ratio and net uptake of triacylglycerol during lactation advance in both groups of 50%HF and 87.5%HF animals feeding either hay or urea treated rice straw. These results suggest that the adaptations to either hay or urea treated rice straw by the mammary gland of crossbred HF animals allow for an adequate nutrient supply during pregnancy and lactation. There is no difference in the mode of mammary uptake of substrates in the same crossbred animals in response to feeding hay or urea treated rice straw. The differences in utilizing nutrients by the mammary gland for milk production between 87.5%HF and 50%HF animals would be dependent on changes in both intra-mammary factors and extra-mammary factors.