• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.448-451
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• 2008

Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were used to rocket nozzle flow, those were coupled with the methods of computational fluid dynamics code. For a design of high temperature rocket nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be an efficient design tool for predicting maximum thermodynamic performance of the nozzle. Frozen fluid analysis presents the minimum performance of the nozzle because of no consideration for the energy recovery. On the other hand, the case of chemical-equilibrium analysis is able to forecast the maximum performance of the nozzle due to consideration for the energy recovery that is produced for the fast reaction velocity compared with velocity of moving fluid. In this study, using the chemical equilibrium flow analysis code that is combined the modified frozen-equilibrium and the chemical-equilibrium. In order to understand the thermochemical characteristic components and the accompanying energy recovery, shifting-equilibrium flow analysis was carried out for the 30 $ton_f$-class KARI liquid rocket engine nozzle together with frozen flow. The performance evaluation based on the 30 $ton_f$-class KARI LRE nozzle flow analyses will provide an understanding of the thermochemical process in the nozzle and performances of nozzle.

• Reproductive and Developmental Biology
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• v.35 no.3
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• pp.329-334
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• 2011

This study was conducted to establish a freezing method of miniature pig spermatozoa. The semen 더aculated from PWG M-type miniature pig was collected by gloved-hand method. The semen was diluted with same volume extender (m-Modena B). The frozen solution used frozen solution of four different (LEY, TCG, BF-5 and m-Modena+egg yolk) for find optimal frozen solution in miniature pig sperm. The diluted semen for frozen rate assay was added to LEY solution (solution I: 11% lactose+egg yolk; solution II: solution I+glycerol+OEP), and frozen depending on freezing rate by the three different freezing methods (A: until $5^{\circ}C$ for 1 hrs, holding at $-102^{\circ}C$ for 10 min; B: until $5^{\circ}C$ for 2 hrs, holding at $-102^{\circ}C$ for 10 min; C: until $5^{\circ}C$ for 3 hrs, holding at -80 and $-102^{\circ}C$ for 10 min). Semen cooled until $5^{\circ}C$ was added with glycerol 1, 3 and 5%, and take a equilibrium time for 0, 10 and 30min. Frozen-thawed sperm were evaluated for viability, acrosomal status and morphological abnormality. The results of frozen-thawed sperm ability by frozen solution, viability was higher in LEY solution compared to other three different frozen solution. AR pattern of LEY solution were lower than other three different frozen solution. The results of freezing rate, viability was higher in B method compared to other methods (p<0.05). Acrosomal statute was intacted in A and B methods than C method. The experiment for glycerol condition was showed that sperm viability was higher in extender with 1% and 3% glycerol and equilibrium time of 0 min. The acrosome damage was lower in extender with 1% glycerol and equilibrium time of 10 min than other conditions. In conclusion, the optimal conditions for cryopreservation of miniature pig spermatozoa obtained in LEY frozen solution, cooling rate of 1~2 hrs, 1~3% glycerol concentrations and glycerol equilibrium time of 0~10 min.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.90-98
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• 2001

Characteristics of high temperature rocket nozzle flow is discussed along with the aspects of computational analysis. Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were discussed, those were coupled with the methods of computational fluid dynamics code. A chemical equilibrium code developed for the analysis of general hydrocarbon fuel was coupled with three approaches of nozzle flow analysis. The approaches were used for the performance prediction of KSR-III Rocket, and compared with the theoretical results from NASA CEA (Chemical Equilibrium with Applications) code.

• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.40-45
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• 1996

This paper discribes the viscous interaction of Hypersonic Wedge Flows using Roe FDS and AUSM+. For this purpose we developed the frozen and the equilibrium code and numerically simulated the viscous interaction by changing the surface temperature and the mach number. We used curve fitting data in NASA Reference Publication 1181, 1260 to calculate equilibrium properties. We compare the equilibrium flow with the frozen flow. We conclude that the mach number and the surface temperature are significant parameters, as the surface temperature and the mach number increase the viscous interaction becomes stronger, and we must consider high-temperature effects in hypersonic flow

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.105-109
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• 2007

Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were used to rocket nozzle flow, those were coupled with the methods of computational fluid dynamics code. For a design of high temperature rocket nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be an efficient design tool for predicting maximum thermodynamic performance of the nozzle. In this study, shifting-equilibrium flow analysis was carried out for the 30 $ton_f$-class KARl liquid rocket engine nozzle together with frozen flow. The performance evaluation based on the 30 $ton_f$-class KARl LRE nozzle flow analyses will provide an understanding of the thermochemical process in the nozzle and performances of nozzle.

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.144-148
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• 2001

Characteristics of high temperature rocket nozzle flow is discussed along with the aspects of computational analysis. Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were discussed those were coupled with the methods of computational fluid dynamics. A chemical equilibrium code developed for the analysis of general hydrocarbon fuel was coupled with three approaches of nozzle flow analysis, and a test was made for a bell nozzle at typical operation condition. As a results, the characteristics of the approaches were discussed in aspects of rocket performance, thermal analysis and computational efficiency.

• Korean Journal of Veterinary Research
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• v.32 no.1
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• pp.143-151
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• 1992

Sixty Four fresh and 142 frozen embryos of dairy cattle were transferred to synchronized dairy, beef or Korean Native Cattle nonsurgically at National Animal Breeding Institute from 1985 to 1990. The results obtained were as follows ; 1. The pregnancy rate of fresh embryos(39.1%) was higher than that of frozen embryos(32.4%) and average pregnancy rate was 34.5%. 2. The pregnancy rate of grade 1 embryos was higher than that of grade 2 embryos for both fresh(41.3% vs 33.3%) and frozen embryos(35.4% vs 25.6%). 3. The pregnancy rate according to development stage of fresh embryos was increased with maturity as 29.2%, 33.3%, 50.0% and 54.5% for morula, early blastocyst, blastocyst and expanded blastocyst, respectively. For frozen embryos, the pregnancy rate of blastocyst(44.4%) was higher than those of morula(31.3%) and early blastocyst(28.0%). 4. The pregnancy rate according go recipient-donor synchrony for fresh embryos was higher when the recipients exhibited estrus 1 day earlier than the donors(43.8%) than when the recipients exhibited estrus 1 day later than the donors(38.1%) or when the recipients and donors exhibited estrus at the same time(37.0%). For forzen embryos, the pregnancy rate was decreased when the recipients and donors exhibited estrus at the same time(37.9%), when the recipients exhibited estrus 1 day later than the donors(32.0%) and when the recipients exhibited estrus 1 day earlier than the donors(23.5%), in sequence. 5. The pregnancy rate of heifers was higher than that of cows for both fresh(50.5% vs 37.9%) and frozen embryos(39.7% vs 25.7%). 6. The pregnancy rate according to recipient breed for fresh embryos was higher in dairy cattle(42.1%) and beef cattle(40.%) than in Korean Native Cattle(33.3%). For frozen embryos, the pregnancy rate was decreased beef cattle(39.1%), dairy cattle(30.3%) and Korean Native Cattle(14.3%), in sequence. 7. The pregnancy rate according to equilibrium steps of glycerol and freezing rate was higher when transferred after 3-steps equilibrium and freezing by the rate of $0.3^{\circ}C$/min from $-6^{\circ}C$ to $-35^{\circ}C$ and $0.1^{\circ}C$/min to $-38^{\circ}C$(39.4%) than when transferred after 6-steps equilibrium and freezing by the rate of $0.5^{\circ}C/min$ from $-6^{\circ}C$ to $-30^{\circ}C$(30.3%).

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.3
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• pp.9-15
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• 2008

Nozzle flow analyses of $30\;ton_f$-class KARI liquid rocket engine for high altitude propulsion are carried out using a chemically frozen and equilibrium flow analysis code developed previously. It is considered that the combined frozen- and shifting- equilibrium analysis is cost-effective regarding the convergence characteristics and modeling uncertainties, though the non-equilibrium analysis is most reliable approach. A dependable performance prediction could be attainable through the present analyses that account for the recombination process and thermal and kinetic energy recovery during the expansion process with viscous effects.

• The Journal of Fisheries Business Administration
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• v.40 no.2
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• pp.105-126
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• 2009

This study applies the cointegration theory to analyse the causality of the prices between imported fisheries and domestic fisheries in distribution channel. We've focused on the prices of import, wholesale and retail about the frozen Alaska pollack, hairtail and croaker which take up high portion and are popular among most of the consumers. In process of analysis, the unit root test was adopted to find the stability of time series data prior to the cointegration test. If the time series data was found as stable one in unit root test, we should analyse the VAR model. If unstable, the cointegratioin test was adopeted to find the long-run equilibrium relationship between the data. When the long-run equilibrium relationship was found among the price of the import, wholesale and retail price, the VECM model was adoped. If not, the differenced VAR model was adopted. The main findings of this study could be summarized as follows ; First, according to the result of the analysis on VAR model, time series data of frozen Alaska pollack was found as stable and has causality relationship and close effect was existing among the import, wholesale and retail price. Second, the data of frozen hairtail was found as an unstable one in unit root test and the result of cointegration test showed the long-run equilibrium relationship at lag 1. From the results of VECM model, we could find that the coefficient of error correction is effective, and the sign is negative(-). It means that the existence of adjustment tendency to long-run equilibrium after a short-run deviation. But the short-run causality of the prices were not found except the price of wholesale. Third, according to the results of differenced VAR model, data from frozen croaker did not have the stability and long-run equilibrium. Moreover, it was found that the import price has a weak causality on the retail price. Because of having difficulties in collecting data, the result of this paper could not explain the relationship among the prices of import, wholesale and retail perfectly. However, it more or less contributed to a long-lasted debate on the direction of causality of price-setting in academic research and provided a useful guide for the policy makers in charge of the price-setting of fisheries products as well.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.85-96
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• 2003

For a design of rocket engine nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be used as an efficient design tool for predicting maximum thermodynamic performance of the nozzle. 10 this study, a chemical equilibrium flow analysis code was developed for the design of hydrocarbon fueled rocket engines. 10 oder to understand the thermochemical characteristics occurring in a nozzle through the expansion process, such as recombination of chemical components and the accompanying energy recovery, chemical equilibrium flow analysis was carried out for the KSR-III rocket engine nozzles together with frozen flow and non-equilibrium flow analyses. The performance evaluation based on the present KSR-III nozzle flow analyses has provided an understanding of the thermochemical process in the nozzle and additionally, it has confirmed that the newly designed nozzle shape modified to have a reduced exit area ratio is an adequate design for obtaining an increased ground thrust.