• Journal of Fisheries and Marine Sciences Education
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• v.9 no.2
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• pp.198-208
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• 1997

Recently, with rapid increase of gas demand, there occurs much interest their security of safety in the gas storage tanks and pressure vessels etc. In order to solve the problems, the occurrence of corrosion fatigue crack and the propagation behavior must be investigated. Especially the occurrence of corrosion fatigue crack and the propagation behavior in the part which has concentrated stress or defects, must be studied more carefully. In this paper, the high-tensile steel of SPV 50 which is much used for building the LPG storage tanks was tested by the use of a plane bending corrosion fatigue tester under the various marine environment and in the air. These experiments were carried out to investigate the surface crack propagation behavior, the value of experimental constant for Paris' rule(da/dN=$C(K)^m$), the crack depth propagation rate and the accelerative factor of the surface crack propagation rate. The main results obtained are as follows ; 1) As the specific resistances of marine environment decreases, the exponential value of slope m of Paris' rule(da/dN=$C(K)^m$) decreases and the value of intercept C increases. 2) The surface crack propagation rate and the crack depth propagation rate are delayed, as the specific resistances of marine environment is increased. 3) The accelerative factor of the surface crack propagation rate by corrosion fatigue is higher, according as the stress intensity factor range ${\Delta}K_A$ is small.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.862-868
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• 2012

Based on the recently derived general expression for the rates of diffusion-controlled reactions, we calculate the rates of dismutation of the superoxide anion radical catalyzed by Cu/Zn superoxide dismutases (SOD). This is the first attempt to calculate the absolute rates of diffusion-controlled enzyme reactions based on the atomiclevel molecular dynamics simulations. All solvent molecules are included explicitly and the effects of the structural flexibility of enzyme, especially those of side chain motions near the active site, are included in the present calculation. In addition, the actual mobility of the substrate molecule is taken into account, which may change as the molecule approaches the active site of enzyme from the bulk solution. The absolute value of the rate constant for the wild type SOD reaction obtained from MD simulation is shown to be in good agreement with the experimental value. The calculated reactivity of a mutant SOD is also in agreement with the experimental result.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.88-93
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• 1987

Chitosan ($\beta$-D-glucosaminan) is chemically prepared from chitin (N-acetyl-$\beta$- D-glucosaminan) which is an unutilized natural resource. We now report on the suitability of the chitosan matrix for use as vehicles for the controlled release of drugs. Salicylic acid and aspirin were used as model drugs in this study. The permeation of salicylic acid in the chitosan membranes was determined in a glass diffusion cell with two compartments of equal volume. Drug release studies on the devices were conducted in a beaker containing 5% sodium hydroxide solution. Partition coefficient (Kd) value for acetate membrane (472) is much greater than that for fluoro-perchlorate chitosan membrane (282). Higher Kd value for acetate chitosan membrane appears to be inconsisstent with the bulk salicylic acid concentration. The permeability constants of fluoro-perchlorate and acetate chisotan membranes for salicylic acid were 3.139 ${\times}10^{-7}cm^2$ min up to 60 min and that of 30% aspirin in the devices was 4.739${\times}10^{-7}cm^2$sec upto 60 min. As the loading dose of aspirin in a chitosan device increased, water up-take of chitosan device increased, but in case of salicylic acid it decreased. The release rate increased with increase in the molecular volume of the drugs. Thses result suggest that the release mechanism may be controlled mainly by diffusion through pores.

• Preventive Nutrition and Food Science
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• v.10 no.4
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• pp.333-339
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• 2005

Three lactobacillus strains, two from infant feces, and one from cow's milk, were selected among 172 isolates, from multiple sources, for further study based on the antimicrobial activities against six strains of pathogenic bacteria and identified as Lactobacillus acidophilus. The strains revealed a wide scope of spectrum against pathogenic bacteria. Viable Lactobacillus acidophilus KH-l cell counts at pH 2.0 were slightly decreased to $1.42\times10^7$ CFU/mL from $4.18\times10^7$ CFU/mL, while remaining at $3.42\times10^7$ CFU/mL at pH 4.0 with the survival rate of $33.97\%\;and\;81.82\%$, respectively. At the concentration of $0.1\%$ oxgall, L acidophilus KH-l kept growing up to $3.12\times10^7$ CFU/mL with a mean growth rate constant (k) of 0.25, and cell number was slightly decreased to $1.21\times10^7$ CFU/mL (k=0.19) with $0.3\%$ oxgall, but remained at $7.6\times10^6$ CFU/mL (k=0.17) with $0.5\%$ oxgall. L. acidophilus KH-l had a $D_{60}$ value of 7.14, with viable cell numbers $1.4\times10^5$ CFU/mL after heat treatment at $60^{\circ}C$ for 30 minutes. Stability of L acidophilus KH-l at $-20^{\circ}C$ was significantly higher, when the strain was cultivated under the optimum growth temperature $(54.41\%\;and\;54.35\%)$ than at the temperature $(13.53\%)$.

• Journal of Advanced Navigation Technology
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• v.21 no.3
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• pp.220-229
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• 2017

In this paper, To take advantage a variety of DC power as the boost DC-DC converter design specifications through the inductor L and capacitor C through PSPICE to calculate the best estimate of the value. Boost DC-DC converter with a switch device using IRF840 and reverse recovery time Schottky diodes with excellent with constant current controller using D10SC6M and resistance can be configured to considering the Power LED Module was driven by the production. Converter's switching frequency is 50 kHz, the first Duty Rate was made to increase gradually depending on the value of the detection were, 10 % in the output voltage. As a result, the simulated Boost Power LED driver characteristics is in comparison with the design specifications, 5% or less as the error was approximated. Finally, when input 15 V were offered, a stable output 24 V were obtained. and Dimming Control through the adjustment of brightness and current consumption were possible.

• The Korean Journal of Nuclear Medicine
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• v.3 no.1
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• pp.1-12
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• 1969

Liver functions in diffuse parenchymal liver disease such as cirrhosis of the liver depend largely on the effective hepatic blood flow rather than on the individual cell functions. Clinical methods of measuring the hepatic blood flow were developed recently by the application of colloidal disappearance rate. In order to correlate the radiogold disappearance rate to conventional biochemical liver function tests, 21 normal subjects and 80 cases of cirrhosis of the liver were studied with both methods. The results are summarized as following: 1. The validity of external counting method to measure the blood disappearance rate of colloidal radiogold was confirmed by in vitro counting of the serial blood samples. 2. The blood disappearance rate of collidal radiogold was essentially the same. as the liver uptake rate of colloidal radiogold in normal and cirrhotic subjects with various degrees of functional disturbance. And it seemed there was no serious extrahepatic removal of the colloidal radiogold. 3. The disappearance rate of colloidal radiogold was not significantly changed by the posture change, but was enhanced by ingestion of 500 ml of water. 4. The disappearance rate of colloidal radiogold was not influenced by single dose of Telepaque, while BSP retention was increased after Telepaque. 5. The mean disappearance half time of colloidal radiogold in normal subjects was $2.49{\pm}0.391$(S.D.) minutes. The mean normal disappearance rate constant (K value) was $0.285{\pm}0.0428$(S.D.)/minute. 6. The colloidal radiogold disappearance half time was abnormally prolonged (over 3.2 min.) in $87.7{\pm}3.68$(S.D.) % of cirrhotic subjects. 7. In patients of liver cirrhosis the blood disappearance rate of colloidal radiogold correlated well to serum albumin and globulin levels and BSP retention which were considered to reflect functions of hepatic parenchymal cells. There was, however, no correlation between colloidal disappearance rate and thymol turbidity test, serum glutamic pyruvic transaminase, and serm alkaline phosphatase activities. The latters were considered to be associated with the activity of liver disease.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.2
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• pp.173-180
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• 1996

4-probe resistivity measurement technique was used to study kinetics of hydrogen absorption-desorption on Pd film($520{\AA}$ thick) at room temperature upto 1 bar. Kinetics data are fitted well to 1st order kinetics equation in ${\alpha}$ and ${\alpha}^{\prime}$ phases. In ${\alpha}+{\alpha}^{\prime}$ phase, absorption kinetics was very complicated, but it could be explained partially with nucleation and growth process. Ln(dR/dt) vs. time plot gives rate constant k value(R is resistance of sample, t is time). k value for absorption is $4^{-6}{\times}10^{-4}/sec$ in ${\alpha}$ phase. k is increasing upto $4^{\times}10^{-2}/sec$ as hydrogen pressure increasing in ${\alpha}^{\prime}$ phase. k is proportional to ln(Pop/Peq), where Peq is equilibrium plateau pressure and Pop is the opposing pressure. In contrast to bulk sample k value was decreasing with increasing number of A-D cycling in ${\alpha}^{\prime}$ phase absorption.

• Environmental Engineering Research
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• v.25 no.2
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• pp.243-250
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• 2020

A down-flow hanging sponge (DHS) bioreactor was operated for the treatment of domestic wastewater. The Stover-Kincannon model was applied for kinetic evaluation of the reactor performance during the operational period. As a result, the coefficient of determination (R²) for straight lines of effluent concentration from the experimental data and from the predictive data of BOD₅; NH₄⁺-N; and TN were 0.9727; 0.9883; and 0.9934, respectively. The calculation of saturation value constant (Umax - g L^-1 d^-1) and maximum utilization rate constant (KB - g L-1 d-1) were 56.818 and 75.034 for BOD₅; 2.960 and 4.713 for NH₄⁺-N; 2.810 and 8.37 for TN, respectively. The study suggests that Stover-Kincannon model can be used for effective evaluation of kinetic removal of BOD₅; NH₄⁺-N; and TN from domestic wastewater treated in a DHS bioreactor.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.4
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• pp.119-126
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• 1996

Influence factors and efficiency characteristics for treatment of wastewater containing phenol were studied with using Pseudomonas sp. B3. It took 130 hours to remove phenol, when only activated sludge of terminal disposal palnt of sewage was innoculated in batch culture, but it was required just 36 hours, when bacteria degrading phenol and activated sludge were simultaneously innoculated. If only phenol an carbon source was used, it necessary 36 hours for biodegradation of phenol, while glucose was added to medium, it took 73 hours. It was revealed as excellent effluent and SVI, when the F/M ratio, COD and phenol concentration were 53mg/l and 1.2mg/l, respectively, and optimum F/M ratio was revealed 0.31. The reactor were seriously shocked as reducing hydraulic retention time at constant phenol concentration more than increasing phenol concentration at constant hydraulic retention time, when volumetric loading rate was increased to $0.8kg\;phenol/m^3{\codt}d$ from $1.6kg\;phenol/m^3{\codt}d$. And also the effluent phenol concentration was 34mg/l after starting 12 hours of shocking and reactor was recovered as steady state after 65 hours of changing in the former test. Although the effluent phenol concentration was maximum value with 12mg/l after starting 20 hours of shocking and reactor was recovered as steady state after 54 hours of changing in the later test.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.63-68
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• 2019

Dielectric and piezoelectric properties of PIN-PMN-PT piezoelectric single crystals with variation of temperature and compressive stress were investigated. The crystal phase of the single crystal was changed from the ferroelectric rhombohedral structure to tetragonal structure in the 110℃ region and from the tetragonal structure to the paraelectric cubic structure in the 190℃ region. The piezoelectric constant and relative dielectric constant were calculated from the rate of change of polarization and displacement with the application of electric field, which was similar to the value measured from the instrument. As the compressive stress applied to the sample increased, the piezoelectric constant d₃₃ and relative dielectric constant values tended to increase. When the compressive stress applied to the sample at 5℃ was 60 MPa, the d₃₃ was calculated as 4,500 pC/N. At 60℃, the relative dielectric constant of 62000 was calculated when the compressive stress applied to the sample was 40 MPa. The increase in piezoelectric constant and relative dielectric constant when the compressive stress increased could be attributed to the phase transition from the rhombohedral structure to orthorhombic.