• Journal of Embryo Transfer
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• v.26 no.1
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• pp.65-70
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• 2011

This study was conducted to investigate the survival rate of AndroMed and Tris-egg yolk extender for cryopreservation of Korean Native Bull Semen (Chick Cow). Semen was collected from a Korean Native Bull Semen over 3 year's old. The semen was diluted 1:1 by AndroMed and Tris-egg yolk extender. The pellet was diluted to final sperm concentration of $5{\times}10^7$ cell/ml by doubling in every 10 minutes at $4^{\circ}C$ cold chamber. The semen was equilibrated for 1 hrs at cold chamber and packed to 0.5 ml straw. The semen straws were located above 5 cm of liquid nitrogen for 5 minutes. And then the frozen straw was plunged to LN2. The presented straws were examined the viability and motility after thawed at $37^{\circ}C$ water bath. The survival rates was significantly higher (p<0.05) in Tris-egg yolk extender than AndroMed extender ($89.7{\pm}19.8$ vs. $73.4{\pm}11.2$). However, motility was no significant differences ($78.4{\pm}18.7$ vs. $67.9{\pm}14.6$). Survival rate in time of equilibration between visual and CASA program had higher in 2 h ($86.33{\pm}9.4$ vs. $92.32{\pm}12.4$) than in 5 h ($78.20{\pm}7.8$ vs. $88.28{\pm}13.1$) 15 h ($65.24{\pm}6.6$ vs. $76.48{\pm}17.3$) 20 h ($56.26{\pm}4.6$ vs. $67.73{\pm}18.4$). The development rates to cleavage was higher in Tris-egg yolk extender than AndroMed extender (82.2% vs. 81.7%). Similarly, the development rates to blastocyst was significantly higher (p<0.05) in Tris-egg yolk extender than AndroMed extender (42.3% vs. 29.6%). In conclusion, the obvious impact of this study will be its practical application to improve viability and fertilizing ability of cryopreserved spermatozoa used for in vitro fertilization (IVF) and AI, Which in turn will be beneficial to animal genetic resources conservation.

• Journal of Embryo Transfer
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• v.13 no.3
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• pp.313-321
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• 1998

This study was conducted to investigate the effects of equilibration and dilution methods on the survival rate of vitrified IVM-IVF bovine blastocysts. Vitrification solution was composed with 20% glycerol, 20% ethylene glycol, 3/8 M sucrose and 3/8 M dextrose in D-PBS supplemented with 20% FBS (GESD). Embryos were equilibrated in 1 of 3 methods: 3-step (El), 2-step (E2), or 1-step (E3), and after loading into 0.25-ml straws, were plunged into liquid nitrogen. After warming in water bath at 2$0^{\circ}C$, cryoprotectants were diluted in 1 of 3 methods: 1) D1(VS+1/2 M sucrose, 1/2 M sucrose and l/4 M sucrose), 2) D2 (1/2 M sucrose and 1/4 M sucrose), or 3) D3(1/2 M sucrose only). All procedures except warming were conducted at room temperature. Survival and hatching rates of blastocysts and expanded blastocysts following equilibration methods were 50 and 83.6%, and 27.8 and 67.3%, respectively in El, which were significantly higher (P〈0.01) than those of E2 (16.7 and 23.2%, and 7.4 and 12.5%, respectively) and 23 (0 and 3.7%, and 0 and 0%, respectively). Survival and hatching rates of expanded blastocysts were significantly (P〈0.01) higher than those of blastocysts in El. Survival rates of blastocysts and expanded blastocysts following dilution methods were 52% and 80.6% in D2, which were significantly higher (P〈0.05) than those of D1 (29.6 and 48.3%) and D3 (47.2 and 63.8%). Hatching rates of blastocysts were similar in D1, D2 and D3, however in expanded blastocysts, that of D2(61.3%) was significantly higher (P〈0.01) than that of D1(34.5%). Survival rates of expanded blastocysts in D1 and D2, and hatching rates in D2 and D3 were significantly higher(P〈0.01) than those of blastocysts. These results indicate that the viability of vitrified blastocysts was improved by the several steps of equilibration, and by 2-steps dilution after warming, independently of their stage of development. The results also indicated that the expanded blastocysts are more profitable to vitrification than blastocysts.

• Journal of Embryo Transfer
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• v.21 no.3
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• pp.263-271
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• 2006

The purpose of this study was undertaken to compare ability of frozen-thawed sperm characteristics between two strains (miniature pig and Duroc). The semen was collected by gloved-hand method into a pre-warmed ($37^{\circ}C$) thermos bottle. The semen was diluted with same volume extender and added to LEY solution for freezing. The diluted semen was placed in 0.5 ml straws, and freezing was initiated by exposing the straws to liquid nitrogen ($LN_2$) vapours for 10 min before placing them into $LN_2$ for cryopreservation. The frozen-semen straw were thawed at 20, 37 and $50^{\circ}C$ for 1 min, 45 sec and 10 sec within water-bath. The semen sample were evaluated at 0, 3, 6, 9, and 12 h after incubation at $37^{\circ}C$ for analysis of sperm ability. Abnormality of spermatozoa in miniature pig was significantly (p<0.05) higher than that in Duroc at 0, 9 and 12 h of post-thawing incubation after frozen-thawing. The percentage of F-patterned spermatozoa in miniature pig was significantly (p<0.05) lower, while the percentage of AR (acrosome reacted spermatozoa) pattern was higher in the miniature than in the Duroc. On the other hand, there was no significant difference in the viability of spermatozoa thawed at different temperature ($20^{\circ}C\;and\;37^{\circ}C$) between two species, but the viability in miniature pig was higher (p<0.05) than in Duroc when sperm was thawed at $50^{\circ}C$. In conclusion, this study suggest that suitable freezing method for miniature pig semen is required for increasing post-thawing viability and fertilization capacity.

• Journal of Embryo Transfer
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• v.18 no.1
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• pp.61-68
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• 2003

Considerable attention has been focused on the cryopreservation of semen and estrus induction in dog, as consequence of poor productivity caused by long anestrus period, in order to enhance the productivity of youngs and to preserve the breeds. The objectives of this study were to improve reproductive efficiency of artificial insemination with fresh- and frozen-semen following estrus induction in dog. Fifty infertilie dogs (age 2~3 years) were selected fur the study and divided into three different estrus induction treatment groups. Group 1 : dogs (n=15) were given clomifene (0.1 mg/kg) orally f3r five days at 12 hr intervals. Croup 2: dogs (n=15) were given bromocriptine (50 $\mu$g/kg) orally for five days at 12 hr intervals, followed by single injection intravenously of 500 IU GnRH (Croup 3, n=20) when pro-estrus occurred. After being treated, the dogs were evaluated fur the rates of estrus induction and time interval lapses from treatment to beginning of the pro-estrus. The rates of pregnancy in estrus inducted dogs mated naturally compared to those inseminated artificially with ejaculated fresh semen and frozen-thawed semen. Estrus detection was performed using the method of vaginal smear and confirmed by the plasma progesterone assay. Pregnancy was confirmed by ultrasonograpy on day 25, 35 and 55 post insemination. The ejaculated semen was exposed to a mixture of Tris extender with cryoprotectant (Trisma, 81 mM; TES, 209 mM; citric acid, 6 mM; glucose, 5 mM; glycerol, 8%) and cryopreserved gradually by slow-cooling at 17 co above the surface of liquid nitrogen (L$N_2$) for 23 min. The use of fresh semen, the pregnancy rates were observed 66.6, 66.6, 75.0 and 83.3% in natural estrus, clomifene induced, bromocriptine induced and a combination of GnRH and bromocriptine, respectively. The use of frozen-thawed semen, the pregnancy rates were observed 66.6, 33.3, 50.0 and 60.0% in natural estrus, clomifene induced, bromocriptine induced and a combination of GnRH and bromocriptine, respectively. No difference was observed in the number of offspring produced among natural estrus and treated groups inseminated with fresh or frozen-thawed semen. In conclusion, there was no significant differences in the pregnancy rate of dogs between group treated with a combination of GnRH and bromocriptine and group treated clomifene or bromocriptine only. However, frozen-thawed semen can be used successfully fur artificial insemination in dog.

• Journal of Animal Science and Technology
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• v.48 no.6
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• pp.797-804
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• 2006

The present study was undertaken to investigate the post-thawed survivability of bovine embryo depending on different dose of ethylene glycol and sucrose. Ovaries were collected at local slaughterhouse and the cumulus-oocyte-complexes aspirated from ovaries were in vitro matured, fertilized and cultured at 39°C in an atmosphere of 5% CO2 incubator. For conventional slow-freezing, d 7 or 8 expanded blastocysts were collected. Embryos were equilibrated in 1.5 M and 1.8 M ethylene glycol(EG) with 0.1 M and 0.3 M sucrose in Dulbecco's phosphate-buffered saline(D-PBS) supplemented with 0.5% bovine serum albumin. Embryos were then loaded individually into 0.25ml-straw and placed directly into cooling chamber of programmable freezer precooled to 󰠏7°C, after 2 min, the straw was seeded, maintained at 󰠏7°C for 8 min, and then cooled to 󰠏35°C at 0.3°C/min, plunged and stored in liquid nitrogen for at least 3 days. For thawing, the straw containing embryos were warmed in air for 10 sec and exposed to 37°C water for 20 sec. Straws were then removed from 37°C water. Rates of blastocyst survive and hatching were evaluated at 24 to 72 h post-warming. No difference of the survivability was shown between 1.5 M and 1.8 M EG (71 and 70%, respectively). Addition of 0.1 M sucrose to 1.5 M and 1.8 M ethylene glycol in the freezing solution did not differ significantly embryo survival (74 and 77%, respectively), whereas survival rates was higher(89%) in freezing solution contained 0.3M sucrose to 1.8M EG compared with 0.3M sucrose to 1.5M EG group(71%). However, there was no difference in the overall total cell number between the two groups (122±1.8 vs 131±1.4, respectively). In conclusion, the results suggest that 0.3 M sucrose in 1.8 M EG may be optimal condition for freezing and thawing methods with in vitro produced embryos and may be applied to on-farm conditions for embryo transfer.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.253-261
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• 2005

Catalytic wet oxidation of ppm levels of trichloroethylene (TCE) in water has been conducted using $TiO_2$-supported cobalt oxides at a given temperature and weight hourly space velocity. 5% $CoO_x/TiO_2$ might be the most promising catalyst for the wet oxidation at $36^{\circ}C$ although it exhibited a transient behavior in time on-stream activity. Not only could the bare support be inactive for the wet decomposition reaction, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. Characterization of the $CoO_x$ catalyst by acquiring XPS spectra of both fresh and used Co surfaces gave different surface spectral features of each $CoO_x$. Co $2p_{3/2}$ binding energy of Co species exposed predominantly onto the outermost surface of the fresh catalyst appeared at 781.3 eV, which is very similar to the chemical states of $CoTiO_x$ such as $Co_2TiO_4$ and $CoTiO_3$. The spent catalyst possessed a 780.3 eV main peak with a satellite structure at 795.8 eV. Based on XPS spectra of reference Co compound, the TCE-exposed Co surfaces could be assigned to be in the form of mainly $Co_3O_4$. XRD measurements indicated that the phase structure of Co species in 5% $CoO_x/TiO_2$ catalyst even before reaction is quite comparable to the diffraction lines of external $Co_3O_4$ standard. A model structure of $CoO_x$ present on titania surfaces would be $Co_3O_4$, encapsulated in thin-film $CoTiO_x$ species consisting of $Co_2TiO_4$ and $CoTiO_3$, which may be active for the decomposition of TCE in a flow of water.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.39-42
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• 1999

Perfluoropolymers represent the ultimate resistance to hostile chemical environments and high service temperature, attributed to the presence of fluorine in the polymer backbone, i.e. to the high bond energy of C-F and C-C bonds of fluorocarbons. Copolymers of Tetrafluoroethylene (TEE) and 2, 2, 4Trifluoro-5Trifluorometoxy- 1, 3Dioxole (TTD), commercially known as HYFLON AD, are amorphous perfluoropolymers with glass transition temperature (Tg)higher than room temperature, showing a thermal decomposition temperature exceeding 40$0^{\circ}C$. These polymer systems are highly soluble in fluorinated solvents, with low solution viscosities. This property allows the preparation of self-supported and composite membranes with desired membrane thickness. Symmetric and asymmetric perfluoropolymer membranes, made with HYFLON AD, have been prepared and evaluated. Porous and not porous symmetric membranes have been obtained by solvent evaporation with various processing conditions. Asymmetric membranes have been prepared by th wet phase inversion method. Measure of contact angle to distilled water have been carried out. Figure 1 compares experimental results with those of other commercial membranes. Contact angles of about 120$^{\circ}$for our amorphous perfluoropolymer membranes demonstrate that they posses a high hydrophobic character. Measure of contact angles to hexandecane have been also carried out to evaluate the organophobic character. Rsults are reported in Figure 2. The observed strong organophobicity leads to excellent fouling resistance and inertness. Porous membranes with pore size between 30 and 80 nanometers have shown no permeation to water at pressures as high as 10 bars. However high permeation to gases, such as O2, N2 and CO2, and no selectivities were observed. Considering the porous structure of the membrane, this behavior was expected. In consideration of the above properties, possible useful uses in th field of gas- liquid separations are envisaged for these membranes. A particularly promising application is in the field of membrane contactors, equipments in which membranes are used to improve mass transfer coefficients in respect to traditional extraction and absorption processes. Gas permeation properties have been evaluated for asymmetric membranes and composite symmetric ones. Experimental permselectivity values, obtained at different pressure differences, to various single gases are reported in Tab. 1, 2 and 3. Experimental data have been compared with literature data obtained with membranes made with different amorphous perfluoropolymer systems, such as copolymers of Perfluoro2, 2dimethyl dioxole (PDD) and Tetrafluorethylene, commercialized by the Du Pont Company with the trade name of Teflon AF. An interesting linear relationship between permeability and the glass transition temperature of the polymer constituting the membrane has been observed. Results are descussed in terms of polymer chain structure, which affects the presence of voids at molecular scale and their size distribution. Molecular Dyanmics studies are in progress in order to support the understanding of these results. A modified Theodoru- Suter method provided by the Amorphous Cell module of InsightII/Discover was used to determine the chain packing. A completely amorphous polymer box of about 3.5 nm was considered. Last but not least the use of amorphous perfluoropolymer membranes appears to be ideal when separation processes have to be performed in hostile environments, i.e. high temperatures and aggressive non-aqueous media, such as chemicals and solvents. In these cases Hyflon AD membranes can exploit the outstanding resistance of perfluoropolymers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.