• Journal of the Korean Society for Heat Treatment
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• v.11 no.3
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• pp.159-167
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• 1998

In this study, friction-wear test was carried out on the carburized layer depth of a mechanical structure steel SNCM carburized with RX and LPG for 7hrs at $930^{\circ}C$ and also the wear properties of wear loss, wear rate, coefficient of friction, friction force and friction temperature were investigated. The wear properties for carburized layer of SNCM were tested on dry condition at the room temperature by the thrust load of 49~245N range at sliding speed of 0.2m/sec and the sliding speed of 0.2~1.0m/sec range at thrust load of 98N. Wear loss on the depth of carburizing layer was increased with increasing of thrust load and sliding speed, and with decreasing of hardness. The condition of worn surfaces were showed mild wear at less than the thrust load of 98N and sliding speed of 0.6m/sec but were showed severe wear at more than 98N and 0.6m/sec. The friction load and temperature were increased with increasing of thrust load but with increasing sliding speed was appeared minimum at 0.6m/sec. With increasing thrust load the wear rate was increased and the coefficient of friction was decreased, but with increasing sliding speed the wear rate and the coefficient of friction were decreased in 0.2~0.6m/sec and increased in 0.6~1.0m/sec, therefore 0.6m/sec in this testing is a transition velocity.

• Korean Journal of Animal Reproduction
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• v.14 no.2
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• pp.133-140
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• 1990

This study was conducted to develop a simple and efficient technique for fusing 2-cell mouse embryos to obtain tertraploid embryos. Various concentration of PEG and exposure times were compared in order to determine the best condition for fusion and subsequent of fused embryos. The results obtained were follows ; 1. The incidence of fusion induction treated with 40% PEG(70.8%) and 45%(62.7%) for 60 sec. exposure were higher than those of 40% and 45% PEG for 30 sec., 90 sec., or 120 sec. exposure group. Also, the highest incidence of fusion induction(76.9%) was achieved with 120 sec. exposure at 50% PEG concentration. 2. Fused embryos after PEG treatment were cleavaged 2-to 4-cell, 8-cell, morula and blastocyst at 20-24 hr., 30-34., 44-52 hr., respectively, and were not different from those obtained fleshly. 3. The high proportions of the embryos developed to blastocysts after blastomere fusion with 40% PEG for 60 sec., 45% PEG for 60 sec. and 50% for 120 sec. were 66.7%(42/63), 69.0%(29/42) and 32.0%(16/50), respectively, this trend indicated that the fusion rate was similar to the incidence of fused embryos forming blastocysts. 4. The cell number of blastocyst developed from fused embryos(18.7 2.6) was samller than that of untreated embryos(48.9 1.69)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.66-70
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• 2010

The performance of 75 ton liquid rocket engine combustion chamber for a space launch vehicle was predicted through firing tests at low pressure. In low pressure tests of 75 ton LRE combustor chamber, the combustion characteristic velocity of 1750 m/sec and the specific impulse of 240 sec were obtained which are higher than the low pressure performance of 30ton combustion chamber. The combustion characteristic velocity of 1770 m/sec and the specific impulse of 278 sec at design point for 75 ton LRE combustion chamber were predicted by using the low/high pressure performance correlation of 30ton LRE combustion chamber.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.156-164
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• 2005

The aim of this study was to analyze the isokinetic strength of ankle, lumbar and shoulder in fin swimmers. For this study, 7 male fin swimmers and 7 men general swimmers were selected. Isokinetic strength of ankle, lumbar and shoulder were measured by Biodex System 3,000. Statistical techniques for data analysis were a descriptive statistics and t-test. The results of this study were as following; The first, significant difference between two groups in right and left plantar flexion of ankle at $30^{\circ}/sec\;and\;180^{\circ}/sec$. But no significant difference was found between right and left in two groups. The second, significant difference between two groups in right dorsiflexion of ankle at $30^{\circ}/sec$. The third, significant difference between two groups in extension of lumbar at $60^{\circ}/sec$. The fourth, significant difference between two groups in right flexing of shoulder at $60^{\circ}/sec$ and $180^{\circ}/sec$. As result of this conclusion, the isokinetic strength of ankle and lumbar in fin swimming group showed significantly higher than non-fin swimming group.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.31-39
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• 2007

The purpose of this study was to observe the kinematic pattern of elite women 100m hurdler race from start to finish and analyze how the change of horizontal velocity makes an influence on the athletes' performance. The analysis was based on the performance of Korean elite 100m hurdler A and international elite hurdlers B and C. Following results were drawn from the analyzation of elite 100m hurdlers' technical characteristics; During the race, hurdler A made more than 8 m/s of horizontal velocity at the 3rd, 4th, 6th, and the 7th hurdle. The horizontal velocity peaked at the 4th hurdle with 8.23 m/s. On the other hand, hurdler B and hurdler C maintained more than 8 m/s of horizontal velocity from the 2nd hurdle through the 10th hurdle. Hurdler B's fastest horizontal velocity was 8.67 m/s from the 6th to the 7th hurdle and hurdler C's fastest horizontal velocity was 8.85 m/s from the 5th to the 8th hurdle. From the start line to the 3rd hurdle, the times achieved by hurdlers A, B, and C were 4.90 sec, 4.65 sec, and 4.52 sec. In the middle of the race, which is from the 4th hurdle to the 7th hurdle, hurdlers A, B, and C ran in 9.10 sec, 8.60 sec, and 8.38 sec. And the latter part of the race to the 10th hurdle, the times hurdlers A, B, and C hit were 12.32 sec, 11.66 sec, and 11.32 sec. To the finish line, it took 1.15 sec for hurdler A, 1.1 sec for B, and 1.06 sec for C. Hence, to set the record of sub-13 sec, hurdler A should improve her acceleration from the start line to the 1st hurdle with the speed more than 5.4 m/s and should maintain more than 8 m/s of horizontal velocity from the 2nd hurdle through the 10th hurdle. In addition, hurdler A should improve her speed endurance to minimize the deceleration of horizontal velocity from the 4th hurdle to the final hurdle. If hurdler A could shorten 0.05 sec of time in each hurdle section, she would be able to set the record under 13 seconds.

• Journal of Chest Surgery
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• v.30 no.9
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• pp.914-919
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• 1997

We analyzed the changes of pulmonary function after decortication i 33 patients with chronic empyema thoracis. In 11 patients of them, scintigraphic lung perfusion scan were performed. The results are as follows; 1, Forced expiratory volume in one second(FEVI) increased from 2.30 L/sec to 2.65 L/sec after decorticati on (p = 0.008) . 2. In patients under 20 years-old, PEV 1 increased significantly(p=0.001). 3. In patients who had tuberculosis empyema thoracis, FEVI increased significantly(p=0.008). The post-operative FEVI increased significantly 24 months later(p=0.013). 4. Te post-operative FEV1 increased significantly 24 months later(p=0013). 5. Perfusion and FEV1 of diseased lung changed from 21.5% to 26.9%(p=0.046) and 0.56 L/sec to 0.78 L/sec(p=0.071) after decortication respectively and perfusion of non-diseased lung changed 78.4% to 72.9% after decortication(p=0.042).

• BMB Reports
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• v.44 no.11
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• pp.719-724
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• 2011

The $Sec61{\alpha}$ subunit is the core subunit of the protein conducting channel which is required for protein translocation in eukaryotes and prokaryotes. In this study, we cloned a $Sec61{\alpha}$ subunit from Penicillium ochrochloron ($PoSec61{\alpha}$). Sequence and 3D structural model analysis showed that $PoSec61{\alpha}$ conserved the typical characteristics of eukaryotic and prokaryotic $Sec61{\alpha}$ subunit homologues. The pore ring known as the constriction point of the channel is formed by seven hydrophobic amino acids. Two methionine residues from transmembrane ${\alpha}$-helice 7 (TM7) contribute to the pore ring formation and projected notably to the pore area and narrowed the pore compared with the superposed residues at the corresponding positions in the crystal structures or the 3D models of the $Sec61{\alpha}$ subunit homologues in archaea or other eukaryotes, respectively. Results reported herein indicate that the pore ring residues differ among $Sec61{\alpha}$ subunit homologues and two hydrophobic residues in the TM7 contribute to the pore ring formation.

• Korea-Australia Rheology Journal
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• v.17 no.3
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• pp.125-130
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• 2005

Coalescence process of binary immiscible fluid mixtures having bimodal size distributions, prepared by mixing two pre-sheared samples at different shear rates, ${\gamma}_{pre1}\;and\;{\gamma}_{pre2}$, under shear flow at a final shear rate, ${\gamma}_f$, are examined by transient shear stress measurements and microscopic observations in comparison with the results for simply pre-sheared samples having narrow size distributions (unimodal distribution samples). Component fluids are a silicone oil (PDMS) and a hydrocarbon-formaldehyde resin (Genelite) and their viscosities are 14.1 and 21.0 $pa{\cdot}sec$ at room temperature $(ca.\;20^{\circ}C)$, respectively. The weight ratio of PDMS: Genelite was 7:3. Three cases, $({\gamma}_{pre1}=7.2sec^{-1},\;{\gamma}_{pre2}=12.0sec^{-1}\;and\;{\gamma}_f=2.4sec^{-1}),\;({\gamma}_{pre1}=0.8sec^{-1},\;{\gamma}_{pre2}=4.0sec^{-1}\;and\;{\gamma}_f=2.4sec^{-1}),\;and\;({\gamma}_{pre1}=7.2sec^{-1},\;{\gamma}_{pre2}=12.0^sec^{-1}\;and\;{\gamma}_f=7.2sec^{-1})$ the first case, transient shear stress did not show any significant difference but domains larger than the initial state are observed at short times. In the latter cases, there exist undershoot of shear stress, reflecting existence of deformed large domains, which is confirmed by the direct observation. It is concluded that coalescence between large and small domains more frequently occur than coalescence between the domains with similar size in the bimodal distribution samples.

• Natural Product Sciences
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• v.8 no.2
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• pp.44-47
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• 2002

The effects of Eurycoma longifolia Jack on masculine copulatory behaviour were studied in the middle aged male Sprague-Dawley rats, 9 months old and retired breeders after dosing them with 500 mg/kg twice daily for 10 days prior to test. The test lasted for 30 minutes after a 20 minute adaptation period, was carried out on the 11th day during the dark phase of the light-dark cycle (2000-0700 hours) and in subdued light, using a modified copulation cage but with the presence of a piece of mirror of appropriate size to facilitate observation. Results showed that the mean values of EL-1, EL-2 and EL-3 of the control middle aged male rats were 103.20 sec, 91.21 sec and 80.00 sec but were significantly (p<0.05) increased to 118.40-120.20 sec, 101.24-171.28 sec and 100.42-110.21 sec respectively in the methanol-chloroform, methanol-butanol-water and methanol-butanol treated middle aged male rats. However, further results also showed that PEI-1 and PEI-2 of the control middle aged male rats were 182.30 sec and 257.2 sec but were significantly (p<0.05) decreased to 100.42-121.31 sec and 40.21-132.31 sec respectively in the methanol-chloroform-butanol-water and methanol-butanol treated middle aged male rats. In conclusion, this study showed that although E. longifolia Jack continued to enhance the sexual activity of the middle aged male rats by extending the duration of coitus and decreasing the refractory period between the different series of copulation, but to a smaller degree as compared to sexually active, adult male rats (Ang and Sim, 1997).

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.41-46
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• 2008

To estimate the finger dose absorbed by $^{99m}Tc$ injection, simulations are carried out to calculate the dose equivalent of each finger per second with radioactivity of 370 MBq, based on the GEANT4 simulator. For the $^{99m}Tc$ source of the volume of 0.4mL and the radioactivity of 370 MBq, we obtained the dose equivalent of the right thumb ($0.29\;{\mu}Sv{\cdot}sec^{-1}$), the right index finger ($1.19\;{\mu}Sv{\cdot}sec^{-1}$), the right middle finger ($1.07\;{\mu}Sv{\cdot}sec^{-1}$), the left thumb ($4.36\;{\mu}Sv{\cdot}sec^{-1}$), and the left index finger ($3.37\;{\mu}Sv{\cdot}sec^{-1}$), respectively. This simulation results may serve as a useful data in the prediction of finger dose absorbed by $^{99m}Tc$ injection.