• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.150.1-150.1
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• 2014

Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

• Analytical Science and Technology
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• v.8 no.1
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• pp.1-7
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• 1995

Spectrophotometric determination of U(VI) and Th(IV) by Flow injection method is described. Chrome Azurol S forms water soluble complexes with U(VI) and Th(IV) in the presence of cethyltrimethylammonium bromide. The maximum adsorption of U(VI) and Th(IV) complexes are at 600nm with molar absorptivity of $2.3{\times}10^5Lmol^{-1}cm^{-1}$ and 611nm with molar absorptivity of $3.8{\times}10^5Lmol^{-1}cm^{-1}$ in acetate buffer medium having pH 5.0 and 5.5. The calibration curves of U(VI) and Th(IV) are linear over the range of 0.1~0.8ppm and the correlation coefficients are ca. 0.9960 and 0.9930 respectively. The detection limits(S/N) are 20ppb for U(VI) and 15ppb for Th(IV). The relative standard deviation are ${\pm}1.8%$ for U(VI) and ${\pm}2.1%$ for Th(IV). The sample throughput was ca. $50hr^{-1}$.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.2
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• pp.493-498
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• 2003

Paeoniae Radix, Glycyrrhizae Radix and Jakyakgamchotang have been used in Oriental Medicine for many centuries as a treatment for various disease. The purpose of the present study is to determine the effect of Paeoniae Radix, Glycyrrhizae Radix and Jakyakgamchotang on narepinephrine(NE) induced contraction of isolated rabbit femoral artery. Rabbits (2.0kg, female) were killed by CO₂ exposure and a segment (8-10mm) of the aortic ring from each rabbit was cut into equal segments and mounted 'in pairs' in a tissue bath. Contractile force was measured with force displacement transducers under 1.5g loading tension. The dose of NE which evoked 50% of maximal response (ED/sub 50/) was obtained from cumulative dose response curves for NE (10/sup -7/～10/sup -4/M). Contractions evoked by NE (ED/sub 50/) were inhibited significantly by Paeoniae Radix, Glycyrrhizae Radix and Jakyakgamcho-tang. The mean percent inhibition of NE induced contraction was 83.9% (p<0.01) after 150㎕/㎖ Paeoniae Radix, 101.1 %(p<0.01) after 150 ㎕/㎖, Glycyrrhizae Radix and 107.3%(p<0.01) after 150㎕/㎖ Jakyakgamcho-tang, Indomethacin slightly but significantly attenuated the inhibitory effects of Paeoniae Radix. Following treatment with indomethacin, the mean percent inhibition caused by 150㎕/㎖ Paeoniae Radix fell to 16.4% in femoral artery induced by NE contraction. Propranolol, ODQ, and L-NNA did not significantly alter the inhibitory effect of Paeoniae Radix. ODQ slightly but significantly attenuated the inhibitory effects of Glycyrrhizae Radix. Following treatment with ODQ, the mean percent inhibition caused by 150㎕/㎖ Glycyrrhizae Radix fell to 13.0% in femoral artery induced by NE contraction. Propranolol, indomethacin and L-NNA did not significantly alter the inhibitory effect of Glycyrrhizae Radix. L-NNA slightly but significantly attenuated the inhibitory effects of Jakyakgamchotang. Following treatment with L-NNA, the mean percent inhibition caused by 150㎕/㎖ Jakyakgamchotang fell to 13.8% in femoral artery induced by NE contraction. Propranolol, ODQ and indomethacin did not significantly alter the inhibitory effect of Jakyakgamcho-tang. These results indicate that Paeoniae Radix, Glycyrrhizae Radix and Jakyakgamcho-tang can relax NE induced contraction of the isolated rabbit femoral artery, and that this inhibition related to nitric oxide.

• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.229-235
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• 1992

The bioequivalence of two commercial choline magnesium trisalicylate (CMT) tablets was evaluated in 10 normal male subjects (age 21-27 yr, mean 23 yr) following single oral administrations of two products. Test product was $Trimax^{\circledR}$ tablet (Hyundai Pharm. Ind. Co., Ltd., Korea) and reference product was $Trilisate^{\circledR}$ tablet (Purdue Frederick, U.S.A.). Both products contained 500 mg salicylate. In the study, ten volunteers were administered one tablet of $Trimax^{\circledR}$ or $Trilisate^{\circledR}$ with randomized two period cross-over study. The pharmacokinetic parameters of two products were statistically compared using Student's t-test and ANOVA. When Student's t-test was applied, mean area under the curves (AUC) of $Trilisate^{\circledR}$ and $Trimax^{\circledR}$ were $388.88{\pm}74.99\; {\mu}g{\cdot}hr/ml$ and $390.63{\pm}63.02\;{\mu}g{\cdot}hr/ml$ hrlm!, respectively, which were not significantly different (p>0.05). The mean peak concentrations $(C_{max})$ and mean times to peak $(T_{max})$ of $Trilisate^{\circledR}$ and $Trimax^{\circledR}$ were $71.1{\pm}12.2$ and $72.9{\pm}10.7\;{\mu}g/ml$, and $72{\pm}33$ and $57{\pm}36min$, respectively, which were not significantly different (p>0.05). The mean terminal phase half-lives $(t_{l/2ter})$ of the two products were $2.57{\pm}0.47$ and $2.43{\pm}0.40$ hr, and also they were not significantly different (p>0.05). When ANOVA was applied, the parameters of the two products were not also significantly different each other. Based on the above results, it has been concluded that the bioavailability of $Trimax^{\circledR}$ tablet was not significantly different from that of $Trilisate^{\circledR}$ tablet.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.942-947
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• 2001

Thickness dependence of orientation on piezoelectric and electrical properties was investigated by PZT (52/48) films by diol based sol-gel method. The thickness of each layer by spinning at one time was $0.2{\mu}m$ and crack-free films could be successfully deposited on 4 inches Pt/Ti/$SiO_2$/Si substrates by 0.5 mol solutions in the range from $0.2{\mu}m$ to $3.8{\mu}m$. Excellent P-E hysteresis curves were achieved, which were attributed to the well-densified PZT films and columnar grain without pores or any defects between interlayers. The (111) preferred orientation of films were shown in the range of thickness below $1{\mu}m$. As the thickness increased, the (111) preferred orientation disappeared from $1{\mu}m$ to $3{\mu}m$ region, and the orientation of films became random above $3{\mu}m$. Dielectric constants and longitudinal piezoelectric coefficient, $d_{33}$, measured by pneumatic method were saturated around the value of about 1400 and 300 pC/N respectively above the thickness of $1{\mu}m$.

• Korean Journal of Acupuncture
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• v.18 no.1
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• pp.157-164
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• 2001

Radix Asteris has been used in Korea for many centuries as a treatment for respiratory disease. The effect of Radix Asteris on tracheal smooth muscle is not known. The purpose of the present study is to determine the effect of Radix Asteris on histamine induced tracheal smooth muscle contraction in rats and guinea pigs. Guinea pig(500g, male) and Sprague Dawley rats (250g, male) were killed by $CO_2$ exposure and a segment (8-10mm) of the thoracic trachea from each rat and guinea pig was cut into equal segments and mounted 'in pairs' in a tissue bath. Contractile force was measured with force displacement transducers under 0.5g loading tension. The dose of histamine (His) which evoked 50% of maximal response ($ED_{50}$) was obtained from cumulative dose response curves for histamine $(10^{-7}{\sim}10^{-4}M)$. Contractions evoked by His ($ED_{50}$) were inhibited significantly by Radix Asteris. In guinea pig tracheal smooth muscle, the mean percent inhibition of histamine induced contraction was 120.5% (p<0.01) after $100{\mu}l/ml$ Radix Asteris. In rat tracheal smooth muscle, the mean percent inhibition of histamine induced contraction was 135.4% (p<0.01) after $100{\mu}l/ml$ Radix Asteris. Propranolol $(10^{-7}M)$ slightly but significantly attenuated the inhibitory effects of Radix Asteris. Following treatment with propranolol, the mean percent inhibition caused by $100{\mu}l/ml$ Radix Asteris fell to 44.6% in guinea pig induced by histamine contraction and by $100{\mu}l/ml$ Radix Asteris fell to 18.7% (p<0.05) in rat induced by histamine contraction. Indomethacin and methylene blue$(10^{-7}M)$ did not significantly alter the inhibitory effect of Radix Asteris. These results indicate that Radix Asteris can relax histamine induced contraction of guinea pig and rat tracheal smooth muscle, and that this inhibition involves sympathetic effects.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.3
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• pp.153-158
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• 2011

Objective: The aim of this study was to investigate whether anti-M$\ddot{u}$llerian hormone (AMH) levels could be predict ovarian poor/hyper response and IVF cycle outcome. Methods: Between May 2010 and January 2011, serum AMH levels were evaluated with retrospective analysis. Three hundred seventy infertile women undergoing 461 IVF cycles between the ages of 20 and 42 were studied. We defined the poor response as the number of oocytes retrieved was equal or less than 3, and the hyper response as more than 25 oocytes retrieved. Serum AMH was measured by commercial enzymelinked immunoassay. Results: The number of oocytes retrieved was more correlated with the serum AMH level (r=0.781, $p$ <0.01) than serum FSH (r=-0.412, $p$ <0.01). The cut-off value of serum AMH levels for poor response was 1.05 ng/mL (receiver operating characteristic [ROC] curves/area under the curve [AUC], $ROC_{AUC}$=0.85, sensitivity 74%, specificity 87%). Hyper response cut-off value was 3.55 ng/mL $ROC_{AUC}$=0.91, sensitivity 94%, specificity 81%). When the study group was divided according to the serum AMH levels (low: <1.05 ng/mL, middle: 1.05 ng/mL - 3.55 ng/mL, high: >3.55 ng/mL), the groups showed no statistical differences in mature oocyte rates (71.6% vs. 76.5% vs. 74.8%) or fertilization rates (76.9% vs. 76.6% vs. 73.8%), but showed significant differences in clinical pregnancy rates (21.7% vs. 24.1% vs. 40.8%, $p$=0.017). Conclusion: The serum AMH level can be used to predict the number of oocytes retrieved in patients, distinguishing poor and high responders.

• Journal of Sensor Science and Technology
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• v.25 no.6
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• pp.440-446
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• 2016

This study introduces the characteristics of current-voltage (I-V) and impedance variance for $ZnO-Zn_2BiVO_6-Co_3O_4$ (ZZCo), which is sintered at $900^{\circ}C$, according to temperature changes. ZZCo varistor demonstrates dramatic improvement of non-linear coefficient, ${\alpha}=66$, with lower leakage current and higher insulating resistivity than those of ZZ ($ZnO-Zn_2BiVO_6$) from the aspect of I-V curves. While both systems are thermally stable up to $125^{\circ}C$, ZZCo represents a higher grain boundary activation energy with 1.05 eV and 0.94 eV of J-E-T and from IS & MS, respectively, than that of ZZ with 0.73 eV and 0.82 eV of J-E-T and from IS & MS, respectively, in the region above $180^{\circ}C$. It could be attributed to the formation of $V^*_o$(0.41~0.47 eV) as dominant defect in two systems, as well as the defect-induced capacitance increase from 781 pF to 1 nF in accordance with increasing temperature. On the other hand, both the grain boundary capacitances of ZZ and ZZCo are shown to decrease to 357 pF and 349 pF, respectively, while the resistances systems decreased exponentially, in accordance with increasing temperature. So, this paper suggests that the application of newly formed liquid phases as sintering additives in both $Zn_2BiVO_6$ and the ZZCo-based varistors would be helpful in developing commercialized devices such as chips, disk-type ZnO varistors in the future.

• Journal of radiological science and technology
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• v.21 no.1
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• pp.35-39
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• 1998

We analyzed image factors to determine the characteristic factors that need for intelligent replenishment system of the auto film processor. We processed the serial 300 sheets of radiographic films of chest phantom without replenishment of developing and fixation replenisher. We took the digital data by using film digitizer which scaned the films and automatically summed up the pixel values of the films. We analyzed characteristic curves, average gradients and relative speeds of individual film using densitometer and step densitometry. We also evaluated the pH of developer, fixer, and washer fluid with digital pH meter. Fixer residual rate and washing effect were measured by densitometer using the reagent methods. There was no significant reduction of the digital density numbers of the serial films without replenishment of developer and fixer. The average gradients were gradually decreased by 0.02 and relative speeds were also gradually decreased by 6.96% relative to initial standard step-densitometric measurement. The pHs of developer and fixer were reflected the inactivation of each fluid. The fixer residual rates and washing effects after processing each 25 sheets of films were in the normal range. We suggest that the digital data are not reliable due to limitation of the hardware and software of the film digitizer. We conclude that average gradient and relative speed which mean the film's contrast and sensitivity respectively are reliable factors for determining the need for the replenishment of the auto film processor. We need more study of simpler equations and programming for more intelligent replenishment system of the auto film processor.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.24-31
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• 2004

Purpose : To know the differences of proton MR spectroscopic features between recurrent rectal cancer and fibrosis in post-operative period, and to evaluate the possibility to discriminate recurrent rectal cancer from post-operative fibrosis by analysis of proton MR spectra. Materials and Methods : We evaluated the proton MR spectra from 25 soft tissue masses in perirectal area that developed in post-operative period after operation for the resection of rectal cancer. Our series included 11 cases of recurrent rectal cancer and 14 of fibrotic mass. All cases of recurrent rectal cancer and post-operative fibrosis were confirmed by biopsy. We evaluated the spectra with an attention to the differences of pattern of the curves between recurrent rectal cancer and post-operative fibrosis. The ratio of peak area of all peaks at 1.6-4.1ppm to lipid (0.9-1.6ppm) [P (1.6-4.1ppm/P (0.9-1.6ppm)] was calculated in recurrent rectal cancer and post-operative fibrosis groups, and compared the results between these groups. We also evaluated the sensitivity and specificity for discriminating recurrent rectal cancer from post-operative fibrosis by analysis of $^1H-MRS$. Results : Proton MR spectra of post-operative fibrosis showed significantly diminished amount of lipids compared with that of recurrent rectal cancer. The ratio of P (1.6-4.1ppm)/P (0.9-1.6ppm) in post-operative fibrosis was much higher than that of recurrent rectal cancer with statistical significance (p < .05) due to decreased peak area of lipids. Mean (standard deviations of P (1.6-4.1ppm)/P (0.9-1.6ppm) in post-operative fibrosis and recurrent rectal cancer group were $2.71{\pm}1.48\;and\;0.29{\pm}0.11$, respectively. With a cut-off value of 0.6 for discriminating recurrent rectal cancer from post-operative fibrosis, both the sensitivity and specificity were $100\%$ (11/11, and 14/14). Conclusion : Recurrent rectal cancer and post-operative fibrosis can be distinguished from each other by analysis of proton MR spectroscopic features, and $^1H-MRS$ can be a new method for differential diagnosis between recurrent rectal cancer and post-operative fibrosis.