• Physical Therapy Korea
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• v.13 no.4
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• pp.30-38
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• 2006

This study was to investigate the influence of cooling on muscle force and viscoelastic properties of tendon structures in themedial gastrocnemius (MG) muscle. The subject was instructed to gradually increase force (10% MVC step) from a relaxed state to MVC within 3 s. At this time, it was measured by an ultrasonographic probe was attached and that an electrode was attached to monitor EMG. The F values at 50 100% of MVC were significantly greater under the cold condition than under the non-cold condition (p<.05). The ${\Delta}F/{\Delta}L$ values at 80~100% of MVC were significantly higher under the cold condition than under the non-cold condition (p<.05). The elongation under the non-cold condition had a tendency to be greater than that under the cold condition. The results suggest that cooling results in an increase in the stiffness of tendon structures with a reduction of muscle force and elongation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.237-237
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• 2010

고효율의 열전특성을 갖는 나노 구조체 열전재료 연구의 일환으로 이종물질인 $Bi_2Te_3$-PbTe계 열전소재의 미세구조와 특성을 조사하였다. 계단식 냉각법(step cooling)를 통하여 시편을 제조 하였고, EPMA를 이용하여 시편의 미세구조를 관찰하였다. 열전소재의 상분리를 유도하기 위하여 $700^{\circ}C$에서 용융 후 3일 동안 $400^{\circ}C$로 유지시킨 후 상온까지 용융로에서 서냉하였다. EPMA를 이용하여 제조된 시편의 미세구조와 정량 분석을 하였고, 각 상의 결정구조 확인을 위하여 XRD 분석법을 이용하여 다결정의 PbTe와 $Bi_2Te_3$ 그리고 준안정상인 $PbBi_2Te_4$가 관찰 되었다. 계단식 냉각법을 통한 시편의 열전특성을 측정하였다. 이를 통하여 제조된 시편은 급속 냉각법으로 제조된 시편과 비교되었으며, 제벡계수는와 열전도도는 상온에서 각각 약 -100mV/K와 0.9W/mK로 약90%, 40%의 열전특성 향상을 확인하였다.

• Transactions of Materials Processing
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• v.11 no.7
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• pp.581-588
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• 2002

Among the processes to produce micro lens, the process using press molding is a new technology to simplify the process, but it contains many unknown variables. The press-molding process proposed in this paper was simplified into two step process, the first step is the pressing to design the preform for glass element, the second step is the annealing to reduce the residual stress. It is important to estimate the amount of shrinkage of glass gob and the residual stress during process. It Is difficult to evaluate the process variables as mentioned above through the experiment. The influences due to process variables was evaluated by using FEM parametric analysis. The results in this paper can be applicable to produce micro lens.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.8-18
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• 2006

The aim of this study is to evaluate the emission characteristics of mercury, lead, arsenic, and selenium from medium size municipal solid waste incinerators(MSWIs) in Korea. The concentrations of mercury, lead, arsenic, and selenium emitted from medium size MSWI stack were $2.67\;{\mu}g/Sm^3,\;0.38\;mg/Sm^3,\;1.33\;{\mu}g/Sm^3,\;0.28\;{\mu}g/Sm^3$, respectively. The concentration levels of mercury, lead, arsenic in flue gas from medium size MSW incinerator stacks selected were nearly detected under the Korea criteria level. Removal efficiencies of mercury, lead, arsenic, and selenium in waste heat boiler(WHE) and cooling tower(CT) were $90.36\%,\;69.76\%,\;43.04\%,\;40.64\%$, respectively. In general, the removal efficiencies of mercury and lead in WHE were higher than those of arsenic and selenium in WHE. Emission gas temperature reduction from waste heat boiler(WHB) and cooling tower(CT) can control mercury and lead of medium size MSWIs. To evaluate the relationship between mercury, lead, arsenic, selenium of fly ash and those of flue gas, it was carried out to correlation analysis of each metal concentration in the fly ash and in the flue gas from medium size MSWIs. From the correlation analysis, the coefficients of mercury, lead, arsenic, and selenium were 0.61, -0.38, 0.87, 0.28, respectively. The results of correlation analysis revealed that it should be highly positive to the correlation coefficients of mercury and arsenic in the fly ash and those of the flue gas emitted from medium size MSWIs. As it were, the concentrations of mercury and arsenic of flue gas from medium size MSWIs are high unless mercury and arsenic in fly ash are properly controlled in dust collection step in medium size MSWIs. It was also concluded that mercury, lead, arsenic, and selenium from MSWIs stacks could be controlled by waste heat boiler(WHE) and dust collecting step in medium size MSWIs.

• Bulletin of the Korean Chemical Society
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• v.21 no.3
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• pp.281-290
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• 2000

We varied recombination method of fenetic algorithm (GA), i.e., crossover step, to compare efficiency of these methods, and to find more optimum GA method. In one method (A), we select two conformations(parents) to be recombined by systematic combination of lowest energy conformations, and in the other (B), we select them in a ratio proportional to the energy of the conformation. Second variation lies in how to select crossover point. First, we select it randomly(1). Second, we select range of residues where internal energy of the molecule does not vary for more than two residues, select randomly among such regions, and we select either thr first (2a) or the second residue (2b) from the N-terminal side, or the first (2c) or the second residue (2d) from the C-terminal side in the selected region for crossover point. Third, we select longest such hregion, and select such residue(as cases 2) (3a, 3b, 3c or 3d) of the region. These methods were tested in a 2-dimensionl lattice system for 8 different sequences (the same ones used by Unger and Moult., 1993). Results show that compared to Unger and Moult's result(UM) which corresponds to B-1 case, our B-1 case performed similarly in overall. There are many cases where our new methods performed better than UM for some different sequences. When cooling factor affecting higher energy conformation to be accepted in Monte Carlo step was reduced, our B-1 and other cases performed better than UM; we found lower energy conformers, and found same energy conformers in a smaller steps. We discuss importance of cooling factor variation in Monte Carlo simulations of protein folding for different proteins. (A) method tends to find the minimum conformer faster than (B) method, and (3) method is superior or at least equal to (1) method.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.72-78
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• 2022

A vacuum brazed cooling passage for an aircraft engine controller was designed. In order to predict the total pressure loss, which is the main design factor of the cooling passage, theoretical and numerical methods for the major loss and the minor loss considering the overall shape of the cooling passage are presented. This design and evaluation method can predict the pressure loss of the complex cooling passage shape for various flow conditions at the initial design step.

• Korean Journal of Dental Materials
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• v.44 no.3
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• pp.207-216
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• 2017

The effect of cooling rate on precipitation hardening of a Pd-Cu-Ga-Zn metal-ceramic alloy during porcelain firing simulation was investigated and the following results were obtained. When the cooling rate was fast (Stage 0), the hardness of the alloy increased at each firing step and the high hardness value was maintained. When the cooling rate was slow (Stage 3), the hardness was the highest at the first stage of the firing, but the final hardness of the alloy after complete firing was lower. The increase in hardness of the specimens cooled at the cooling rate of Stage 0 after each firing step was caused by precipitation hardening. The decrease in hardness of the specimens cooled at the cooling rate of Stage 3 after each firing step was attributed to the coarsening of the spot-like precipitates formed in the matrix and plate-like precipitates. The matrix and the plate-like precipitates were composed of the $Pd_2(Cu,Ga,Zn)$ phase of CsCl-type, and the particle-like structure was composed of the Pd-rich ${\alpha}$-phase of face-centered cubic structure. Through the porcelain firing process, Cu, Ga, and Zn, which were dissolved in Pd-rich ${\alpha}$ particles, precipitated with Pd, resulting in the phase separation of the Pd-rich ${\alpha}$ particles into the Pd-rich ${\alpha}^{\prime}$ particles and ${\beta}^{\prime}$ precipitates composed of $Pd_2(Cu,Ga,Zn)$. These results suggested that the durability of the final prosthesis made of the Pd-Cu-Ga-Zn alloy can be improved when the cooling rate is fast during porcelain firing simulation.

• The Korean Journal of Food And Nutrition
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• v.33 no.4
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• pp.440-446
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• 2020

The purpose of this study was to derive the conditions for manufacturing rice porridge with optimum properties after reheating. The characteristics of rice porridge according to the soaking time, water addition rate, heating temperature, heating time, and cooling conditions were compared using the 'Samkwang' cultivar. In Step I, as the heating temperature increased, the weight change decreased and the viscosity increased, and the temperature known as the main factor of the gelatinization also appeared to affect the viscosity increase. In Step II, the viscosity and the texture properties was not significantly different as the soaking time was reduced, and 10 minutes was suitable because of due to the shortening effect of the total process time. In Step III, the residual heat was lowered by cooling after the rice porridge production, so the viscosity could be greatly reduced. Also, it was confirmed that the water addition rate of 900% and the heating temperature of 15 minutes were optimal manufacturing conditions. The next study will investigate the porridge processability of rice cultivars using these results.

• Clinical and Experimental Reproductive Medicine
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• v.28 no.1
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• pp.55-63
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• 2001

Objectives: This study was carried out to evaluate the effects of embryonic stage, cryoprotectant, and freezing-thawing method on the rates of survival and development of the cryopreserved mouse early embryo and finally to establish the cryopreservation method of surplus embryos obtained during assisted reproductive technology (ART). Materials and Methods: Two to eight cell embryos were obtained from oviducts of mated $F_1$ hybrid female mice superovulated by pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG). Two-step 1,2-propanediol (PROH), dimethylsulfoxide (DMSO) and 4-step PROH DMSO were used as cryoprotectant and dehydration and rehydration method of embryos, and slow-cooling or rapid-cooling method was used as frozen program. The survival rates of embryos were measured after thawing and rehydration, and the developmental rates of embryos were compared and observed during culturing embryos for 24, 48, 72, 96 hrs. Results: As for the survival and development rates of embryos according to embryonic stage, the survival rate of 2 cell stage in PROH and DMSO was significantly higher than 4-8 cell (64.5% versus 62.1 %,79.7% versus 73.2%) (p<0.01, p<0.01), but the development rates of 4-8 cell embryos in PROH and DMSO were significantly higher than 2 cell embryos for whole culture period (p<0.01) and the development rates of 4-8 cell embryos in PROH were significantly higher than 2 cell embryos in DMSO (p<0.01). As for the survival and development rates of embryos according to cryoprotectant, the survival rate of 2 cell embryo in DMSO was significantly higher than that in PROH (74.4% versus 64.5%) (p<0.01), whereas the development rate of embryos was not differ till 24 hrs. The developmen1 rate from morular to hatching blastocyst, however, was significantly higher in PROH than in DMSO during 48 hr (p<0.01). The survival rate of 4-8 cell embryo was 62.1% in PROH and 73.2% in DMSO. The development rates of embryo in PROH were significantly higher for whole culture periods (p<0.01, 0.05). In respect to the effect of freezing and thawing program on the survival and development rates of embryos, method of slow cooling and rapid thawing was more effective than that of rapid cooling and rapid thawing. Conclusions: The survival rate of embryo in 2 cell stage was higher than in 4-8 cell stage, and PROH appears more effective cryoprotectant than DMSO because PROH showed better development rates of embryos in 2 and 4-8 cell stage. Moreover, slow cooling and rapid thawing method was considered as the best cryopreservation program.

• Korean Journal of Animal Reproduction
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• v.11 no.3
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• pp.161-169
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• 1987

This experiment was carried out to investigate the optimal cooling rate and the plunging temperature into liquid nitrogen of the 8-cell hamster embryos. The female hamsters were induced to superovulate by intraperitoneal injection of 30 i.u. PMSG. Embryos were flushed from oviduct and uterine horn. Embryos were frozen and incubated with a modified Dulbecco's phosphate buffered saline, and equilibrated with 1.5M-dimethyl sulfoxide by a 3-step procedure. The cooling rate of samples was 1$^{\circ}C$/min from room temperature to -5$^{\circ}C$ and the samples were seeded at -5$^{\circ}C$. The plunging temperatures into liquid nitrogen were -20, -25, -30, -35, -40, -45, -50 and -55$^{\circ}C$ at 0.3$^{\circ}C$/min, 0.5$^{\circ}C$/min and 1$^{\circ}C$/min cooling rates, respectively. This mean numbers of ovulation points and recovered embryos were 59.4 and 48.4 appearing 81.6% recovery rate. The percentage of 8-cell embryos in recovered embryos was 68.2. The survival rates of embryos plunged at -45$^{\circ}C$ were 73.5% at 0.3$^{\circ}C$/min, 44.8% at 0.5$^{\circ}C$/min and 30.3% at 1$^{\circ}C$/min cooling rates, respectively. This mean numbers of ovulation points and recovered embryos were 59.4 and 48.4 appearing 81.6% recovery rate. The percentage of 8-cell embryos in recovered embryos was 68.2. The survival rates of embryos plunged at -45$^{\circ}C$ were 73.5% at 0.3$^{\circ}C$/min, 44.8% at 0.5$^{\circ}C$/min and 30.3% at 1$^{\circ}C$/min cooling rates, respectively. The survival rates at 0.3$^{\circ}C$/min were significantly high. Under the condition of 0.3$^{\circ}C$/min cooling rate, the survival rates of embryos according to the plunging temperature were 70.0% and 73.5% at -40 and -45$^{\circ}C$, and those were higher than other plunging temperatures. Under the condition of 0.5$^{\circ}C$/min and 1$^{\circ}C$/min cooling rates, the survival rates according to the plunging temperatures were lower than the cooling rate of 0.3$^{\circ}C$/min, showing the similar tendency at all the plunging temperatures. In conclusion, 8-cell hamster embryos showed the best survival rates at 0.3$^{\circ}C$/min cooling rate and -45$^{\circ}C$ plunging temperature.