• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.703-711
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• 1992

As the underground area of the metropolitan becomes denser recently, an introduction of forced cooling system is under study to maximize the carrying capacity of existing cables in tunnels. Indirect water cooling system laid within trough will probably be adopted for the next 345KV class underground power cables in this country. The system covers a distance of 1.5-3.0Km for one water cooling interval and one water cooling interval is composed of several sub-sections that have different thermal analysis conditions. Thus the distribution of temperature in each sub-section is described by different conditions in general. In this paper a method that can accurately match the temperature of the coolant in the boundary between sub-sections has been suggested. An algorithm to find the temperature distributions effectively in the thermal system has also been presented. A computer program using this method has been tested in a smaple system and the results have shown the usefulness of this program.

• Radiation Oncology Journal
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• v.4 no.2
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• pp.107-113
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• 1986

Radiation myelitis is a rather rare, but irreversible fatal complication. Etiology, pathologic change, clinical symptoms and the method of diagnosis have been studied with animal experiments and human necropsies. In spite of massive studies, pathogenesis of post-irradiation myelitis and the level of tolerance dose still remain controversial. Thoracolumbar spine of 110 hybrid mice were irradiated with orthovoltage x-ray machine. Mild capillary congestion and axonal swelling were observed in 1,000 rad irradiated specimens. Focal necrosis in 3,500 rad specimens, fragmentation of neural tissue in 4,000 rad specimens were also observed. These results suggest that 5,000 rad is not a completely safe tolerable dose which have been accepted and we cannot exclude direct radiation damage to news tissue as the causative pathology of radiation myelitis in addition to blood vessel damage.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.124-124
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• 2003

The successful development of embryos cloned by nuclear transfer (NT)have been dependent on a wide range of known factors including cell cycle of donor and recipient ooplast, oocyte quality, NT procedure and oocyte activation. The present study compared the development of cloned porcine embryos following different activation treatments. Cumulus-oocyte complexes (COCs) were aspirated from 26 mm follicles of slaughterhouse ovaries and cultured for 22 h in NCSU #23 medium supplemented with 10% porcine follicular fluid, 0.57 mM cysteine, 0.5 g/mL LH, 0.5 g/mL FSH and 10 ng/mL EGF. The COCs were further cultured for an additional 22 h in the same medium at $39{\cird}C$ in an atmosphere of 5% $CO_2$ in air, without hormonal supplements. Primary cultures of fibroblasts isolated from a female fetus on day 40 of gestation were established in DMEM + 15% FCS. For nuclear donation, cells at the 5th-6th passage were cultured in DMEM +0.5% FCS for 5 days in order to arrest the cells in G0/Gl. After enucleation, oocytes were reconstructed by transfer of donor cells and fusion with three DC pulses (1.4 KV/cm, 30 sec) in 0.28 M mannitol containing 0.01 mM $CaCl_2$ and 0.01 mM $MgCl_2$. Eggs were then divided into three treatment groups, control (without further treatment, Group 1), eggs cultured in 10 g/ml cycloheximide (CHX) for 5 h (Group 2), and eggs cultured in 1.9 mM 6-dimethylaminopurine (6-DMAP) for 5 h (Group 3). The eggs were then cultured in sets of 30 in 60 I drops of NCSU#23 supplemented with 4mg/ml BSA (essentially fatty acid free) until day 7 at $39{\circ}C$ in a humidified atmosphere of 5% $CO_2$. On day 4 the culture were fed by adding 20 I NCSU #23 supplemented with 10% FBS. Development rates into blastocysts were significantly higher (P<0.05) in Group 3 embryos compared to Group 1 controls ($27.6 \mu 2.7% vs. 20.1 \mu 4.1%$, respectively), but rates did not differ in Group 2 compared to control ($23.8 \mu 5.7%$). Total cell number in Group 3 blastocysts was however significantly higher (P<0.05) than in Groups 1 and 2 ($44.6 \mu 2.4 vs. 19.9 \mu 1.9 and 21.9 \mu 2.1$, respectively). These results suggest that 6-DMAP is more efficient than cycloheximide in the activation of electrically fused NT oocytes during in vitro production of cloned porcine embryos.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.287-298
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• 2019

The aim of the present study was to compare the germination and seedling characteristics of rice varieties grown under various flooding conditions and different temperature and oxygen levels and to identify germplasm suitable for wet direct seeding. Three anaerobic germination tolerant (AGT) genotypes (PBR, WD3, KHO) and eleven Korean rice varieties (KVs) adapted for direct seeding were evaluated for seedling performance under different temperatures (15, 18, 21, and 24℃ ) and oxygen levels (Low, Normal, High). Compared with the KVs, the AGT genotypes (especially KHO and PBR) exhibited relatively high germination and survival rates and coleoptile and radical growth rates under low temperature and low oxygen conditions, thereby indicating their suitability for wet direct seeding. Among the KVs, 'Dongan,' 'Jungan,' and 'Cheongdam' rice exhibited the highest survival rates under low temperature and low oxygen conditions. Three-way ANOVA indicated that temperature had the greater effects on seedling characteristics (43.2-78.0%) than either oxygen level (15.4-37.5%) or genotype (2.0-29.8%) did. Therefore, in direct seeding cultivation, temperature was the most important environmental factor for seedling establishment.

• Reproductive and Developmental Biology
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• v.35 no.3
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• pp.319-327
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• 2011

This study investigated whether the addition of porcine sperm cytosolic factor (SCF) at fusion/activation affects in vitro development of porcine parthenogenetic(PA) and nuclear transfer (NT) embryos. To determine the optimum concentration of SCF, control group of oocytes was activated with 0.3M mannitol (1.0 mM $CaCl_2{\cdot}2H_2O$), other three groups of oocytes were parthenogentically activated with the fusion medium (0.1mM $CaCl_2{\cdot}2H_2O$) supplemented with 100, 200 or 300 ${\mu}$g/ml SCF, respectively. Matured oocytes were activated with two electric pulses (DC) of 1.2 kv/cm for 30 ${\mu}$sec. The activated embryos were cultured in PZM-3 under 5% $CO_2$ in air at $38.5^{\circ}C$ for 6 days. Oocytes activated in the presence of SCF showed a significantly higher blastocyst rate than control (p<0.05). Apoptosis rate was significantly lower in 100 ${\mu}$g/ml SCF group than other groups (p<0.05). Cdc2 kinase activity in control and SCF treatment group of oocytes was determined using MESACUP cdc2 kinase assay kit at 1, 5, 10, 15, 30, 45 and 60 min after activation. Cdc2 kinase activity was significantly decreased (p<0.05) in SCF group than MII oocytes or control within 5 min. For NT embryo production, reconstructed oocytes were fused in the fusion medium supplemented with 0.1 mM $CaCl_2{\cdot}2H_2O$ (T1), 1.0 mM $CaCl_2{\cdot}2H_2O$ (T2) and 0.1 mM $CaCl_2{\cdot}2H_2O$ with 100 ${\mu}$g/ml SCF (T3). Fused embryos were cultured in PZM-3 under 5% $CO_2$ in air at $38.5^{\circ}C$ for 6 days. Developmental rate to blastocyst stage was significantly higher in T3 than other groups (23.0% vs. 13.5 to 15.2%) (p<0.05). Apoptosis rate was significantly lower in T3 than T1 or T2 (p<0.05). The relative abundance of Bax-${\alpha}$/Bcl-xl was significantly lower in in vivo or SCF group than that of control (p<0.05). Moreover, the expression of p53 and caspase3 mRNA was significantly lower in in vivo or SCF group than that of control (p<0.05). These results indicate that the addition of SCF at fusion/activation might improve in vitro development of porcine NT embryos through regulating cdc2 kinase level and expression of apoptosis related genes.

• Radiation Oncology Journal
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• v.25 no.3
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• pp.185-191
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• 2007

Purpose: This study was performed to investigate the effects of immune cell activation and the antitumor effect for the combination of treatment with X-irradiation and E/eutherococcus senticosus Maxim Root (ESMR) on mouse tumor cells. Materials and Methods: ESMR (250g) was extracted with 80% methanol, concentrated under decompression and lyophilized. To determine whether ESMR is able to activate the immune cells or not, the proliferation of splenocytes in vitro and the number of B cells and T cells in splenic lymphocytes in ESMR-pretreated mice were evaluated. X-irradiation was given to the mouse fibrosarcoma tumor cells (FSa II) by 250 kv X-irradiation machine. The cytotoxicity of ESMR was evaluated from its ability to reduce the clonogenecity of FSa II cells. In X-irradiation alone group, each 2, 4, 6 and 8 Gy was given to FSa II cells. In X-irradiation with ESMR group, 0.2 mg/ml of ESMR was exposed to FSa II cells for 1 hour before X-irradiation. Results: The proliferation of cultured mouse splenocytes and thymocytes were enhanced by the addition of ESMR in vitro. The number of B cells and T cells in mouse splenic lymphocytes was significantly increased in ESMR pretreated mice in vivo. In FSa II cells that received a combination of 0.2 mg/ml of ESMR with X-irradiation exposure, the survival fraction with a dose of 2, 4 and 6 Gy was $0.39{\pm}0.005$, $0.22{\pm}0.005$ and $0.06{\pm}0.007$, respectively. For FSa II cells treated with X-irradiation alone, the survival fraction with a dose of 2, 4 and 6 Gy was $0.76{\pm}0.02$, $0.47{\pm}0.008$ and $0.37{\pm}0.01$. The difference in the survival fraction of the mouse FSa II cells treated with and without ESMR was statistically significant (p<0.05). Conclusion: Treatment with ESMR increased cell viability of mouse splenocytes in vitro and especially the subpopulation of B cells and T cells in splenocytes in ESMR-pretreated mice. However, treatment with ESMR did not increase the level of Th and Tc subpopulations in the thymocytes. Treatment with the combination of ESMR and X-irradiation was more cytotoxic to mouse tumor cells than treatment with X-irradiation alone; this finding was statistically significant.

• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.65-76
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• 1989

The purpose of this study was to observe the effect on the removal of dentinal smear layer and morphological changes of reduced dentin surfaces by various dentin surface conditioners. Thirty-two healthy human premolars extracted due to periodontal or orthodontic reasons were used. The teeth were cross-sectioned to expose dentin at the middle portion of the crown with diamond rotary saw. The specimens were then divided into 8 groups. The sectioned dentin surfaces in group 1 to 4 were grinded with No. 400 grit silicone abrasive paper and those in group 5 to 8 were cut with #700 carbide bur under air-water spray. The grinded or cut dentin surfaces were conditioned with 3% $H_2O$, Dentin Conditioner(GC Inter. Corp., Japan), and Scotchprep(3M Dent Prod., U.S.A) according to manufacturer's directions. All the specimens were dried in room temperature for 48 hours, and gold-coated with Eiko ion coater(Eik-engineering Co.), and observed in Hitachi S-450 Scanning electron microscope at 15-25 KV. The following results were obtained; 1. The dentin surfaces grinded with the silicon abrasive paper were rougher in texture and heavier in amount of smear layer than those cut with the carbide bur. 2. Scrubbing of 3% $H_2O_2$ was not effective in removing dentinal smear layer. 3. 20-second conditioning of Dentin Conditioner (GC Inter. Corp) resulted in the removal of a significant amount of the smear layer without removing the tubular plugs and dissolving the peritubular dentin. 4. Scotchprep removed the smear layer very effectively. But at the same time it dissolved the peritubular dentin. 5. Irrespective of the uses of the silicon carbide abrasive paper or the carbide bur the morphological changes of dentin surfaces treated with the same conditioning agents were similar.

• Reproductive and Developmental Biology
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• v.33 no.2
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• pp.85-91
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• 2009

In this study, in vitro maturation system using fetal bovine serum (FBS) or porcine follicular fluid (pFF) was investigated to produce comparable oocytes to those derived from in vivo. Control group of oocytes was cultured in TCM 199 supplemented with 0.1% polyvinyl alcohol (PVA). Other three groups of oocytes were cultured in TCM 199 supplemented with 10% FBS, 10% pFF or 5% FBS + 5% pFF, respectively. After 44 h maturation, oocytes with the first polar body were activated with two electric pulses (DC) of 1.2 kv/cm for 30 ${\mu}sec$. Also, matured oocytes of four groups were reconstructed and fused. Reconstructed embryos were cultured in PZM-3 under 5% $CO_2$ in air at $38.5^{\circ}C$ for 6 days. The oocytes matured in the medium supplemented with FBS or/and pFF showed significantly higher maturation rates (64.0 vs. 73.9 to 85.2%). In PA embryos, cleavage rates (89.7 vs. 77.1 to 86.6%) and blastocysts rates (30.0 vs. 16.2 to 26.2%) were significantly higher in pFF group (p<0.05). In NT embryos, there was no difference among treatments in cleavage rate, but the blastocyst rates (28.5 vs. 15.5 to 24.6%) were significantly higher in pFF group (p<0.05). The apoptosis rate was significantly higher (p<0.05) in the control than other groups (10.8 vs. 4.9 to 8.2% for PA, 3.1 vs. 0.5 to 1.3% for NT). In order to select the comparable oocyte to in vivo oocytes, each group of oocytes was stained with Brilliant cresyl blue (BCB) after 42h maturation. The matured oocytes were separated according to color of cytoplasm; stained group (BCB+) and unstained group (BCB-). The oocytes matured in the presence of FBS or/and pFF showed significantly higher staining rates (70.3 to 72.7 vs. 35.1%) (p<0.05). To verify the fact that the supplementation of FBS or/and pFF can increase the maturation rates, cdc2 kinase activity, the catalytic subunit of MPF, was determined. The cdc2 kinase activity of the oocytes matured in the medium supplemented with FBS or/and pFF was significantly higher than control group (6.7 to 9.3 vs. 3.8). In conclusion, the supplementation of FBS or/and pFF can support in vitro maturation rate of porcine oocytes through the increment of cdc2 kinase activity level in the cytoplasm.

• Korean Journal of Materials Research
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• v.18 no.7
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• pp.373-378
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• 2008

$Ba(Ti,Sn)O_3$ thin films, for use as dielectrics for MLCCs, were grown from Sn doped BaTiO3 sources by e-beam evaporation. The crystalline phase, microstructure, dielectric and electrical properties of films were investigated as a function of the (Ti＋Sn)/Ba ratio. When $BaTiO_3$ sources doped with $20{\sim}50\;mol%$ of Sn were evaporated, $BaSnO_3$films were grown due to the higher vapor pressure of Ba and Sn than of Ti. However, it was possible to grow the $Ba(Ti,Sn)O_3$ thin films with {\leq}\;15\;mol%$ of Sn by co-evaporation of BTS and Ti metal sources. The (Ti＋Sn)/Ba and Sn/Ti ratio affected the microstructure and surface roughness of films and the dielectric constant increased with increasing Sn content. The dielectric constant and dissipation factor of $Ba(Ti,Sn)O_3$ thin films with {\leq}\;15\;mol%$ of Sn showed the range of 120 to 160 and $2.5{\sim}5.5%$ at 1 KHz, respectively. The leakage current density of films was order of the $10^{-9}{\sim}10^{-8}A/cm^2$ at 300 KV/cm. The research results showed that it was feasible to grow the $Ba(Ti,Sn)O_3$ thin films as dielectrics for MLCCs by an e-beam evaporation technique.

• Journal of People, Plants, and Environment
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• v.23 no.5
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• pp.545-554
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• 2020

Background and objective: Moth orchids in the vegetative stage are suitable for a multi-layer growing environment in a closed-type plant factory which can be a good alternative that can reduce production costs by reducing cultivation time and energy cost per plant. This study was conducted to find out the optimal rhizospheric environment for different irrigation methods without a potting medium and rhizospheric ventilation for the vegetative growth of young Phalaenopsis hybrid 'Blanc Rouge' (P. KV600 × P. Kang 1) and Phalaenopsis Queen Beer 'Mantefon' in a closed-type plant factory system. Methods: The one-month-old clonal micropropagules with bare roots rapped with a sponges were fixed on the holes of styrofoam plates above growth beds, and were watered using the ebb-and-flow (EBB) and aeroponic (AER) methods with Ichihashi solution (0.5 strength) once a day at 06:00 (P) or 18:00 (S), and both (PS). Rhizospheric ventilation (V) was also applied to change the temperature, relative humidity, and CO₂ concentration of the beds. Plants potted into sphagnum moss and watered once a week were used as the control group. Results: After 12 months of treatment, the growth characteristics of the EBB groups were the best among the treatment groups without a medium, but no effect of irrigation timing was observed. V reduced the temperature, relative humidity and CO₂ concentration of the beds. Whereas, EBB+V (ebb-and-flow with ventilation) improved plant growth and reduced the occurrence of disorders and withering. Especially, EBB+V showed a similar performance to the control group. Conclusion: The results indicated that the optimal irrigation method without a potting medium for producing middle-aged potted moth orchids was the EBB system with forced rhizospheric ventilation. Therefore, further studies on the optimal ventilation method and moisture control of the crown need to be carried out to develop the irrigation system without a potting medium for vertical farming in closed-type plant factories.