• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1734-1743
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• 2003

Aerosol generator using an electrically heated tube furnace is a stable apparatus to supply nanometer sized aerosols by using the evaporation and condensation processes. Using this method, we can generate highly concentrated polydisperse aerosols with relatively narrow size distribution. In this work, characteristics of particle size distribution, generated from a tube furnace, were experimentally investigated. We evaluated effects of several operation parameters on particle generation: temperature in the tube furnace, air flow rates through the tube, size of boat containing solid sodium chloride(NaCl). As the temperature increased, the geometric mean diameter increased and the total number concentration also increased. Dilution with air affected the size distribution of the particles due to coagulation. A smaller sized boat, which has small surface area to contact with air, brings smaller particles of narrow size distribution in comparison of that of a larger boat. Finally, we changed the electrical mobility diameter of aggregate sodium chloride particles by varying relative humidity of dilution air, and obtained non-aggregate sodium chloride particles, which are easy to generate exact monodisperse particles.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.717-725
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• 1996

We have developed an efficient immobilized cell separator for continuous operation of immobilized fungal cell cultures, and applied this separator to actual fermentation process for the production of cyclosporin A (CyA), a powerful immunosuppressant. In the experiments employing highly viscous polymer (carboxymethyl cellulose) solution, the decantor showed good separating performances at high solution viscosites and fast dilution rates. Air duct and cylindrical separator installed inside the decantor turned out to play key roles for the efficient separation of the immobilized cells. By installing the decantor in an immobilized perfusion reactor system (IPRS), continuous immobilized culture was stably carried out even at high dilution rate for a long period, leading to high productivities of free cells and CyA. Almost no immobilized biomass existed in effuluent stream of the IPRS, demonstrating the effectiveness of the decan- tor system for a long-term continuous fermentation. It was noteworthy that we could obtain these results despite of the unfavorable fermentation conditions, i.e., reduced density of the biosupports caused by overgrowth of cells inside the bead particles and existence of high density of suspended fungal cells (10g/l) in the fermentation broth.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.2
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• pp.115-121
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• 2005

Using a general Saccharomyces cerevisiae as a model strain, continuous ethanol fermentation was carried out in a stirred tank bioreactor with a working volume of 1,500 mL. Three different gravity media containing glucose of 120, 200 and 280 g/L, respectively, supplemented with 5 g/L yeast extract and 3 g/L peptone, were fed into the fermentor at different dilution rates. Although complete steady states developed for low gravity medium containing 120 g/L glucose, quasi-steady states and oscillations of the fermented parameters, including residual glucose, ethanol and biomass were observed when high gravity medium containing 200 g/L glucose and very high gravity medium containing 280 g/L glucose were fed at the designated dilution rate of $0.027\;h^{-1}$. The observed quasi-steady states that incorporated these steady states, quasi-steady states and oscillations were proposed as these oscillations were of relatively short periods of time and their averages fluctuated up and down almost symmetrically. The continuous kinetic models that combined both the substrate and product inhibitions were developed and correlated for these observed quasi-steady states.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.908-912
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• 2008

To achieve a higher succinic acid productivity and evaluate the industrial applicability, this study used Mannheimia succiniciproducens LPK7 (knock-out: ldhA, pflB, pta-ackA), which was recently designed to enhance the productivity of succinic acid and reduce by-product secretion. Anaerobic continuous fermentation of Mannheimia succiniciproducens LPK7 was carried out at different glucose feed concentrations and dilution rates. After extensive fermentation experiments, a succinic acid yield and productivity of 0.38 mol/mol and 1.77 g/l/h, respectively, were achieved with a glucose feed concentration of 18.0 g/l and $0.2\;h^{-1}$ dilution rate. A similar amount of succinic acid production was also produced in batch culture experiments. Therefore, these optimal conditions can be industrially applied for the continuous production of succinic acid. To examine the quantitative balance of the metabolism, a flux distribution analysis was also performed using the metabolic network model of glycolysis and the pentose phosphate pathway.

• Reproductive and Developmental Biology
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• v.28 no.3
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• pp.155-159
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• 2004

This study was carried out to investigate the general characteristics and viability of sperm after freezing and thawing and the pregnancy rates after artificial insemination with thawed semen. The rates of viable sperm after slow and rapid freezing were 87.4±3.85% and 70.8±4.45%, respectively which were significantly lower than that of fresh semen control (91.7±3.45%). The mean concentration of epididymal sperm after dilution in 1.0 ml saline and. 3.0 ml extender in a various concentrations of cryoprotectants was 124.5±48.3 x 10/sup 6/ (range of 45 x 10/sup 6/ to 280 X 10/sup 6/ /ml). There was a significant difference not in the percentage of acrosome-reacted sperm, but in the percentage of capacitated sperm, between fresh and frozen-thawed epididymal semen. When frozen-thawed after diluting with tris-buffer extender containing glycerol, DMSO and ethylene glycol with concentration of 2 to 6%, the rates of epididymal sperm exposed to different cryoprotectants ranged from 14.4±4.7% to 20.7±5.8%, 17.8±5.2% to 36.5±4.9%, and 14.4±4.6% to 18.5±5.3%, respectively which were lower compare to fresh semen control. The pregnancy rate after artificial insemination with frozen semen was 70.6%, whereas that with fresh semen was 90.0% in dogs with naturally induced estrus.

• Korean Journal of Veterinary Service
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• v.15 no.2
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• pp.174-183
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• 1992

This study was conducted to determine the serum antibodies against toxoplasma in swine from breeding-pig farm, pig farm and abattoir by latex agglutination(LA) test. LA test was carried out with commercial Toxo-MT kit (Eiken chemical co.). The results obtained were summerized as follows : 1. The cut-off titer of positive and negative reactions by Toxo-MT antigen used in this experiment was determined as the serum dilution of 1 ; 32. 2. positive rates of toxoplasma antibodies in 823 swine sera were 17.0%(140 cases) by LA test. 3. The toxoplasma antibody detection rates against 194 swine sera in breeding-pig farm, 273 swine sera in pig farm and 356 swine in abattoir were 46.9%(91 cases), 8.4%(23 cases) and 7.3% (26 cases) , respectively. 4. In LA test serum antibody titers in 823 test sera were shown as 51 cases (36.4%) in 1 : 32, 40(28.6%) in 1；64, 17(12.1%) in 1:128, 14(10.0%) in 1：256, 10(7.1%) in 1:512, 5(3.6%) in 1：1,024, and 3(2.1%) in 1 : 2,048. 5. Positive rates of toxoplasma antibodies in swine sera from each breeding-pig farm were 20.0∼61.9%.

• Korean Journal of Animal Reproduction
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• v.23 no.4
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• pp.293-301
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• 1999

This study was to examine whether Hanwoo IVM/IVF/IVC blastocyst can be successfully survived in vitro/in vivo after vitrification and one-step dilution. For vitrification, blastocysts were serially exposed in glycerol (G) and ethylene glycol(EG) mixtures［10% (v Iv) G for 5 min., 10% G plus 20% EG (v/v) for 5 min., and 25% G plus 25% EG (v/v) for 30 sec.］ which is diluted in 10% FBS added D-PBS. And then they were loaded in the straw, placed in cold nitrogen vapor for 3 min. and plunged into L$N_2$(－196$^{\circ}C$). One-step dilution within the straw was done in $25^{\circ}C$ and 36$^{\circ}C$ water for about 5 min. and 3 min., respectively. Recovered embryos after one-step dilution were cultured in cumulus cell mono-layered drop for 48 h or were transferred into recipient cows. When the embryo survival in vitro was assessed to re-expanded and hatched rates at 24 hand 48 h after one-step dilution, the results of vitrified group (85.4, 43.8%) was high, although these results were significantly lower than normal development (100.0, 63.3%) of control group, respectively (P＜0.001, P＜0.05). When in vitro survival of vitrified groups according to developmental stage was compared, the results of fast developed embryos (expanded blastocyst and early hatching blastocyst stage) were significantly higher than those of delayed developed one (early blastocyst stage) after one-step dilution (early hatching: 88.0, 48.0%: expanded: 81.1, 45.3%; early: 66.7, 14.3%) (P＜0.05). Also, in case of in vitro survival of vitrified groups according to embryo age (day 7, 8 and 9), when embryo age was younger, in vitro survival was significantly higher (day 7: 67.3, 34.5%; day 8: 76.9, 40.7%; day 9: 60.9, 23.9%)(P＜0.05). Finally, when in vivo development potential of vitrified and one-step diluted Hanwoo blastocysts was examined, 4 of 8 recipient (50%) cows became confirmed pregnant. These results demonstrated that our vitrification and one-step dilution technique can be applied easily and effectively on field trial without the equipment and embryological skills required for conservative dilution and transfer.

• Journal of Embryo Transfer
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• v.6 no.1
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• pp.13-24
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• 1991

The objective of this experiment was to study some possibilities to simplify freezing, thawing and transfer procedure of one-step straw method comparing with the conventional methods using bovine embryos. The previous work are also designed to investigate the thawing effect by development stage and its quality using the embryos. Results obtained were summarized as follows: 1. A total of 87 embryos from 14 donor cows were frozen-thawed and an average of frozen embryo/donor was 6.2. 2. The survival rates of morula stage(65.4%) were higher than those of blastocyst stage(57.l%) and vice versa in rate of morphological recovery (80% vs 95.4%). However. no significant difference was denoted between them. 3. In difference between the groups of good quality and poor quality. good quality was resulted in a significantly higher embryo survival rate(75%) and recovery rates(95%) than poor quality(P<0.0l). 4. In effects of non-permeable sugar dilution in added to l.0M glycerol. higher survival rates were orderd in sucrose. lactose, raffinose and xylose. But lactose-raffinose, sucrose-trehalose and xylose in added to 2.OM glycerol. 5. The highest survival rates were obtained by direct plunge into the liquid nitrogen with 3.OM concentration both of glycerol and trehalose. 6. The survival rates in vitro condition of one-step and direct plunge methods(75%-87.5%) were significantly higher than those of multiple steps (21.4-52.6%) in in vitro (P<0.0l). However, the results of single-step were critical in comparing to other steps of final pregnant conformation.

• Applied Biological Chemistry
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• v.37 no.4
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• pp.277-286
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• 1994

The pot experiment using $^{15}N$ isotope dilution technique was carried out to calculate the balance of nitrogen of surface applied urea in the rice-soil system. The $^{15}N$ concentration was determined by stable isotope ratio mass spcetrometer (model: VG ISO-GAS MM622). In the pots with $^{15}N$ labeled urea application at the rates of 15 and 30 kg N/10a, the percentage of nitrogen derived from fertilizer (NDFF) in rice was higher at the rate of 30 kg N/10a (average 89%) than at the rate of 15 kg N/10a (average 64%). However, the recovery as percentage of fertilizer N by rice was higher at the rate of 15 kg N/10a (65.5%) than at the rate of 30 kg N/10a (54.2%). The percentage of the fertilizer N remained in extractable inorganic N form at the rates of 15 and 30 kg N/10a were $13.5%\;(NH_4-N\;5.53%,\;NO_3-N\;7.99%)$ and $16.5%\;(NH_4-N\;7.49%,\;NO_3-N\;8.98%)$ in unplanted soil, and $2.0%\;(NH_4-N\;0.63%,\;NO_3-N\;1.32%)$ and$2.3%\;(NH_4-N\;0.87%,\;NO_3-N\;1.40%)$ in soil planted to rice, respectively. The dominant form of inorganic-N in soil after harvest was $NO_3-N$ form rather than $NH_4-N$ form regardless of urea application rate or rice cultivation. The percentage of the fertilizer N remained in organic N form at the rates of 15 and 30 kg N/10a were 65.0 and 41.8% in unplanted soil, and 23.7 and 26.9% in soil planted to rice, respectively. In conclusion, the efficiency of surface-applied urea was greater at the rate 15 kg N/10a than at the rate of 30 kg N/10a.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.4
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• pp.464-469
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• 2000

Experiments were conducted to determine the effects of soybean meal (SBM) as a source of protein and sago meal (SM) as a source of carbohydrate on in situ and in vivo digestibility of dietary components in four male goats (Kambing Katjang) and four male sheep (Malin) weighing 25-35 kg. Rumen volume, as well as rumen fluid dilution rate were also determined. The animals were housed in single pens with individual feeding and drinking troughs and each animal was fitted with a rumen fistula. They were fed two diets : chopped rice straw+200 g soybean meal (SBM), and chopped rice straw+190 g soybean meal+300 g sago meal (SBM+SM). Rice straw was offered ad libitum. The supplements were isonitrogenous (80 g crude protein/animal/d), but the proportions of dry matter (DM), organic matter (OM), crude fibre (CF), neutral detergent fibre (NDF) and acid detergent fibre (ADF) were lower in the SBM supplement (191, 165, 11, 40, 15 g/animal/d for DM, OM, CF, NDF and ADF, respectively) than in the SBM+SM supplement (445, 423, 25, 102, 38 g/animal/d for DM, OM, CF, NDF and ADF, respectively). Two animals from each species were fed either supplement in a cross-over design in two periods. Each period lasted for four weeks. In situ and in vivo digestibility studies were carried out, followed by the determination of rumen volume and rumen fluid dilution rate. The results showed that straw DM and total DM intakes of goats (average of $48.7g/kg\;W^{0.75}$, $72.7g/kg\;W^{0.75}$, respectively) were significantly (p<0.01) higher than sheep (average of $3.56g/kg\;W^{0.75}$, $61.6g/kg\;W^{0.75}$, respectively), but OM, N and GE intakes were not significantly different between the two animal species. When the effect of supplements was compared, animals fed SBM+SM supplement had significantly (p<0.001) higher DM, OM and GE intakes than animals fed SBM supplement. Potential degradabilities of rice straw DM were significantly (p<0.01) higher in goats (average of 48.8%) than in sheep (average of 46.1 %). The supplements had no significant effect on the potential degradabilities of DM, OM and NDF, but they had a significant (p<0.05) effect on the degradation rates of DM and NDF. The addition of sago meal in the diet reduced the degradation rates of DM and NDF of rice straw in the rumen. Potential degradability of DM of soybean meal was not significantly different between animal species as well as between supplements. Sago meal was highly degradable. At 24 h of incubation in the rumen, 90-95% of DM loss was observed. There was a significant interaction between animal species and supplements in the in vivo digestibility of ADF and GE. In animals fed SBM supplement, the in vivo digestibility of ADF was significantly (p<0.05) higher in goats ($50.6{\pm}4.22%$) than in sheep ($44.4{\pm}3.21%$), but digestibility of GE was significantly (p<0.05) higher in sheep ($70.2{\pm}1.93%$) than in goats ($63.0{\pm}3.07%$). The digestibility values of CP and OM were significantly (p<0.05) higher in sheep when compared to goats. Animals fed SBM+SM supplement showed significantly (p<0.05) higher DM and OM digestibility values than animals fed SBM supplement, but digestibility values of CP were significantly (p<0.05) higher in animals fed SBM supplement. Differences in in vivo digestibility values of CF and NDF were not significantly different between animal species or supplements. Water intake, rumen volume ($1/kg\;W^{0.75}$), rumen fluid dilution rate and mean retention time were similar between the two animal species. However, rumen fluid dilution rate and mean retention time was significantly (p<0.01) affected by supplements. Animals fed SBM+SM had faster rumen fluid dilution rate and consequently shorter mean retention time.