• Clinical and Experimental Reproductive Medicine
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• v.28 no.3
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• pp.191-198
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• 2001

Objective : This study was conducted to examine the effect of vitrification on the survival and in vitro development of mice 1-cell zygotes. Method: Effects of exposure to vitrification solution and vitrification, with different concentrations of the cryoprotectant solution, were examined. The 1-cell zygotes were also subjected to a slow freezing-thawing method to compare with vitrification method. Solution composed of ethylene glycol (6.0 M, 5.0 M, 4.0 M) and sucrose (1.0 M) were used as cryopropectant. The experiments employed the method loading the embryos on electron microscope grids. Results: I. The effects of exposure in vitrification solution. 1-cell zygotes were non-toxic at all concentrations of the vitrification solution showing the survival rate between 88.1% and 97.5%. Development into 2-cell was more successful in the higher concentrations of the vitrification solution. Therefore, higher concentrations of the vitirification solution do not seem to cause any problems in vitrification procedure. II. The effects of vitrification method. 1-cell zygotes showed the survival rate between 78.8% and 92.4%. The lowest and the highest survival rate was observed in the 6.0 M and 4.0 M vitrification solution, respectively. 2-cell development rates varied from 77.6% to 91.3%. Blastocyst development rate was shown highest in 5.0 M and the lowest in 4.0 M solution. Therefore, the highest 2-cell and blastocyst development rate was observed in 5.0 M solution. III. Comparison of vitrification and slow freezing-thawing method on 1-cell zygotes. This experiment showed that 1-cell zygotes had the highest survival and development rates in 5.0 M vitrification solution. Vitrified group of 1-cell zygotes, in the 5.0 M vitrification solution, were compared with the group processed in slow freezing-thawing method. The development rate into 2-cell and blastocyst as well as the survival rate were higher in the vitrified group than in the slowly freezed group. Conclusion: 1. The results demonstrate that the best cryoprotectant is a 5.0 M vitrification solution for 1-cell zygotes. 2. Vitrification method significantly increases the survival rate of the 1-cell zygote and its development into 2-cell and blastocyst. Equilibration and exposure time during the vitrification was remarkerbly short in this experiment. Total time, from the exposure to vitirification solution to storage in the liquid nitrogen, was taken only 90 seconds. In contrast, the slow freezing-thawing method have taken more than four hours. Taken together, we presume that the overall time used for the procedure contributes to the results as an important parameter. 3. The loading of 1-cell zygotes on the EM grid is technically more simple and takes less time than the straw or cryo vial method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.103-110
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• 2022

The purpose of this study is to experimentally evaluate the stiffness and strength reduction according to the reinforcing bar details of the vertically divided reinforced concrete shear walls. To confirm the effect of reducing strength and stiffness according to vertical division, four real-scale specimens were fabricated and repeated lateral loading tests were performed. As a result of the experiment, it was confirmed that the strength and stiffness were decreased according to the vertical division. In particular, as the stiffness reduction rate is greater than the strength reduction rate, it is expected that safety against extreme strength can be secured when the load is redistributed according to vertical division. As a result of checking the crack pattern, a diagonal crack occurred in the wall subjected to compression control among the divided walls. It was confirmed that two neutral axes occurred after division, and the reversed strain distribution appeared in the upper part, showing the double curvature pattern. In future studies, it is necessary to evaluate the stiffness reduction rate considering the effective height of the wall, to evaluate additional variables such as wall aspect ratio, and to conduct analytical studies on various walls using finite element analysis.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.380-391
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• 2014

In this study, the scale effect on the performance of the podded propeller of tractor type is investigated. Turbulent flow computations are carried out for Reynolds numbers increasing progressively from model scale to full scale using the CFD analysis. The result of the flow calculation for model scale Reynolds numbers agrees well with that of the experiment of a large cavitation tunnel. The existing numerical analysis indicates that the performance of the podded propeller blades is mainly influenced by the advance coefficient and relatively little by the Reynolds number. However, the drag of pod housing with propeller in operation is different from that of pod housing without propeller due to the acceleration and swirl of propeller slipstream which is altered by propeller loading as well as the pressure recovery and friction according to Reynolds number, which suggests that the pod housing drag under the condition of propeller in operation is the key factor of the scale effect on the performance between model and full scale podded propellers. The so called 'drag ratio', which is the ratio of pod housing drag to total thrust of podded propeller, increases as the advance coefficient increases due to accelerated flow in the slipstream of the podded propeller. However, the increasing rate of the drag ratio reduces continuously as the Reynolds number increases from model to full scale progressively. The contribution of hydrodynamic forces, which acts on the parts composed of the pod housing with propeller operating in various loading conditions, to the thrust and the torque of the total propeller unit are presented for a range of Reynolds numbers from model to full scales.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.130-139
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• 2000

Serial basic tests were conducted for the determination of fundamental kinetics and for the actual application of kinetic parameter to food waste digestion with precise measurement of methane production under a thermophilic condition. The effects of food particle size, sodium ion concentration, and volatile solid (VS) loading rate on the anaerobic thermophilic food waste digestion process were investigated. Results of serial test for the determination of fundamental kinetic coefficients showed the value of k (maximum substrate utilization rate coefficient) and KS (half-saturation coefficient) as $0.24hr^{-1}$ and $700mg/{\ell}$, respectively, for non-inhibiting organic loading range. No inhibition effect was shown until $5g/{\ell}$ of sodium ion concentration was applied to a serum bottle reactor. However, the volume of methane gas was decreased gradually when the concentrations of more than $5g/{\ell}$ of sodium ion applied. All sizes of food waste particle showed the same constants (A : 0.45) but the maximum substrate utilization rate constant ($k_{HA}$) was inversely proportional to particle size. As an average particle size increased from 1.02 mm to 2.14 mm, $k_{HA}$ decreased from $0.0033hr^{-1}$ to $0.0015hr^{-1}$. The result reveals that particle size is one of the most important factors in anaerobic food waste digestion. There was no inhibition effect of sodium ion when VS loading rate was $30g/{\ell}$. And maximum injection concentration of VS loading rate was determined about $40g/{\ell}$.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.122-130
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• 2012

Adhesive bend and shear tests of micro-sized bonded component have been performed to clarify the relationship between effects of heat-treatment on the adhesive strength and the bonded specimen shape using Weibull analysis. Multiple micro-sized SU-8 columns with four different diameters were fabricated on a Si substrate under the same fabrication condition. Heat-treatment can improve both of the adhesive bend and shear strength. The improvement rate of the adhesive shear strength is much larger than that of the adhesive bend strength, because the residual stress, which must change by heat-treatment, should effect more strongly on the shear loading. In case of bend type test, the adhesive bend strength in the smaller diameters (50 and $75\;{\mu}m$) widely vary, because the critical size of the natural defect (micro-crack) should vary more widely in the smaller diameters. In contrast, in case of shear type test, the adhesive shear strengths in each diameter of the columns little vary. This suggests that the size of the natural defects may not strongly influence on the adhesive shear strength. All the result suggests that both of the adhesive bend and shear strengths should be complicatedly affected by heat-treatment and the bonded columnar diameter.

• Asian Journal of Atmospheric Environment
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• v.11 no.3
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• pp.176-183
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• 2017

Although it is well known that rain plays an important role in capturing air pollutants, its quantitative evaluation has not been done enough. In this study, the effect of raindrop size on pollutant scavenging was investigated by clarifying the chemical nature of individual size-resolved raindrops and their residual particles. Raindrops as a function of their size were collected using the raindrop collector devised by our oneself in previous study (Ma et al., 2000) during high atmospheric loading for $PM_{2.5}$. Elemental analyses of solid residues and individual residual particles in raindrops were subsequently analyzed by Particle Induced X-ray Emission (PIXE) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX), respectively. The raindrop number concentration ($m^{-2}h^{-1}$) tended to drastically decrease as the drop size goes up. Particle scavenging rate, $R_{sca.}$ (%), based on the actual measurement values were 38.7, 69.5, and 80.8% for the particles with 0.3-0.5, 0.5-1.0, and $1.0-2.0{\mu}m$ diameter, respectively. S, Ca, Si, and Al ranked relatively high concentration in raindrops, especially small ones. Most of the element showed a continuous decrease in concentration with increasing raindrop diameter. The source profile by factor analysis for the components of residual particles indicated that the rainfall plays a valuable role in scavenging natural as well as artificial particles from the dirty atmosphere.

• Membrane Journal
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• v.6 no.2
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• pp.109-116
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• 1996

This work is a fundamental study for applying hybrid process coupling adsorption with microfiltration to waste-water treatment. Phenol was separated by adsorption on powdered activated carbon, adsorbed phenol with activated carbon was separated by microfiltration. As the particle size in suspension increased, filtration resistance decreased, and effect of particle concentration on resistance was less pronounced. The rate of uptake was greatly dependent on the degree of phenol loading. For a smaller amounts of activated carbon, the change of permeate concentration before break point and phenol loading with time were steeper than in the case of large amounts. Permeate concentration before break point decreased with decreasing particle size, this could be due to the increase of outer surface of particle and film mass transfer coefficient.

• Macromolecular Research
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• v.10 no.5
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• pp.246-252
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• 2002

In order to the development of the delivery device of long-acting local anesthetics for postoperative analgesia and control of chronic pain of cancer patient, fentnyl-loaded poly (L-lactide-co-glycolido) (PLGA, molecular weight, 5,000 g/mole; 50 : 50 mole ratio by lactide to glycolide) microspheres (FMS) were studied. FMS were prepared by an emulsion solvent-evaporation method. The influence of several preparation parameters such as initial drug loading, PLGA concentration, emulsifier concentration, oil phase volume, and fabrication temperature has been investigated on the fentanyl release profiles. Generally, the drug showed the biphasic release patterns, with an initial diffusion followed by a lag period before the onset of the degradation phase, but there was no lag time in our system. Fentanyl was slowly released from FMS over 10 days in vitro with a quasi-zero order property. The release rate increased with increasing drug loading as well as decreasing polymer concentration with relatively small initial burst effect. From the results, FMS may be a good formulation to deliver the anesthetic for the treatment of chronic pain.

• Biomolecules & Therapeutics
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• v.9 no.4
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• pp.298-306
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• 2001

To develop a novel transdermal delivery system of loxoprofen (LP), a potent antiinflammatory and analgesic agent, the effects of vehicle composition and drug loading dose on the skin permeation property were investigated. And in vivo skin absorption property studied by analysing the $C_{max}$ and AUC was investigated after applying the developed plaster systems on rabbit back skin. Addition of isopropyl myristate (IPM) and IPM-diethylene glycol monoethyl ether (DGME) cosolvent in the plaster showed higher permeation rates than those from propylene glycol laurate-DGME cosolvent systems. As the concentration of LP in the plaster increased from 0.56 mg/$\textrm{cm}^2$ to 1.19 mg/$\textrm{cm}^2$, the drug release and skin permeation rates increased linearly. At loading dose of 1.19 mg/$\textrm{cm}^2$, the flux reached 35.6 $\mu$g/$\textrm{cm}^2$/hr. New LP plasters showed a good adhesive property onto skin, and showed no crystal formation. The AU $C_{0-24hr}$ and $C_{max}$ after dermal application of LP plaster (60 mg/70 $\textrm{cm}^2$) were found to be 6951$\pm$230 ng.hr/ml and 400$\pm$44 ng/ml, respectively. And the plasma concentration maintained above 300 ng/ml up to 24 hr period. In the carrageenan-induced rat paw edema test, LP plaster showed similar inhibition rate with marketed ketoprofen (Ketoto $p^{R}$) plaster.aster.r.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.46-54
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• 1998

In this paper, the erect of notch geometries on dynamic stress concentration was investigated by using the dynamic photoelasticity and the drop weight loading system Dynamic stress fields arisen by elastic wave through the loading system around various types of notch geometries were captured by using $10^6/sec$ frame rate Cranz-Shardin camera system with 12 photographic frames. We found that dynamic stress concentrations around the notch tip and comer were highly dependent on the change in notch geometries. The elders of dynamic stress singularity ware determined with respect to varying geometries of notches and we explained dynamic stress concentration in terms of the orders of dynamic stress singularity.