• Journal of Welding and Joining
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• v.10 no.1
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• pp.43-51
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• 1992

The plastic zone formed around a notch tip is important in analyzing the fracture toughness of structures and particularly weld cracks existed in the weld HAZ (heat affected zone) which produces local plastic deformation at the crack tip. Therefore, in order to analyze the fracture toughness in weld HAZ, it is necessary to investigate the new fracture toughness parameter $K_{c}$ $^{*}$ and critical plastic strain energy $W_{p}$ $^{c}$ according to the shape and size of the plastic zone. 1) If the temperature corresponding to $K_{c}$ $^{*}$=130kg-m $m^{-3}$ 2/ is determined, transition temperature $T_{tr}$ the magnitude of plastic zone size, and heat input change depending on the fracture toughness. The blunted amounts of the parent and weld HAZ show mild linear variation until .delta.=0.4mm and then increase very steeply there after. 2) The relation between the plastic strain energy( $W^{p}$ ) and transition temperature( $T_{*}$tr) in parent metal is more sensitive than that of weld HAZ. However, the plastic strain energy depends on the transition temperature, and thus the yield stress, .sigma.$_{ys}$ becomes an important parameter for plastic strain energy. 3) The critical plastic strain energy( $W_{p}$ $^{c}$ ) absorbed by the plastic zone at the notch tip indicated in case of parent metal: 60J/mm, in case of heat input(20KJ/cm): 75J/mm, in case of heat input(30KJ/cm); 50J/mmJ/mm.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1365-1372
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• 2019

The effects of Y and Ti on the microstructure stability and tensile properties of the reduced activation ferritic/martensitic steel have been investigated. The addition of Y and Ti affected the prior austenite grain size due to the pinning of the inclusions. Ti addition of 0.008 wt% to the steel was intended to promote the precipitation of nano-sized carbides with a high resistance to coarsening. 8Ti14Y exhibited a higher yield strength and a lower DBTT than the other alloys due to the fine grain size and additional precipitation hardening by (Ti, Ta)-rich MX. After thermal exposure at $550^{\circ}C$ for 1500 h, yield strength was dropped significantly in exposed 0Ti13Y. On the contrary, a lower reduction of YS was observed in 8Ti14Y. The $M_{23}C_6$ in 0Ti13Y and 8Ti14Y and MX in 25Ti14Y and 39Ti15Y coarsened seriously during ageing, which could be responsible for the reduction of the tensile properties of alloys.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.4
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• pp.325-331
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• 2000

Tumor necrosis $factor-{\alpha}\;(TNF-{\alpha})$ plays important roles in inflammatory responses. Some of tetrahydroisoquinoline (THI) compounds exhibited to inhibit iNOS expression in animal studies and RAW 264.7 cells, but the action of THI on inflammatory reaction was not fully investigated. In the present study, we examined a limited series of THIs (higenamine, YS-51 and THI-52) on the $TNF-{\alpha}$ mRNA expression in mouse peritoneal macrophages by Northern analysis. When thioglycollate-stimulated peritoneal macrophages were incubated with LPS (100 ng/ml), expression of $TNF-{\alpha}$ mRNA was evident and reached its maximum at 2.5 h, which was reduced concentration-dependently by treatment with THIs. When the $TNF-{\alpha}$ activity of macrophage-conditioned media was measured using a TNF-sensitive L929 fibroblast cell line, CCL 1, all THIs increased the cell viability in a concentration dependent manner. The concentrations of THIs used are not cytotoxic by itself when analysed by MTT. Furthermore, nitrite/nitrate level was significantly reduced by the presence of THIs in cells treated with $LPS+interferon-{\gamma}\;(IFN-{\gamma}).$ It is concluded, thus, that these results strongly indicated that THIs can suppress the $TNF-{\alpha}$ expression and reduce NO, which may be useful for the inflammatory disorders.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.207-213
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• 2019

Corrosion and mechanical behavior of the hot-rolled 0.5%Gd-0.8%B-stainless steel to develop a spent nuclear fuel storage material was studied in a simulated nuclear waste treatment condition with rolling condition. The austenite and ferrite phases of the 0.5%Gd-0.8%B-stainless steels are about 88:12. The average austenite and ferrite grain size of the plane normal to rolling, transverse and normal directions of the hot rolled specimens are about 5.08, 8.94, 19.35, 23.29, 26.00 and 18.11 [${\mu}m$], respectively. The average micro-hardness of the as-cast specimen is 200.4 Hv, whereas, that of the hot-rolled specimen are 220.1, 204.7 and 203.5 [$H_v$] for the plane normal to RD, TD and ND, respectively. The UTS, YS and elongation of the as-cast and the hot-rolled specimen are 699, 484 [MPa], 34.0%, and 654, 432 [MPa] and 33.3%, respectively. The passivity was observed both for the as-cast and the hot rolled specimens in a simulated nuclear waste solution. The corrosion potential and corrosion rate of the as-casted specimens are $-343[mV_{SHE}]$ and $3.26{\times}10^{-7}[A/cm^2]$, whereas, those of the hot rolled specimens with normal to ND, RD and TD are -630, -512 and -620 [$mV_{SHE}$] and $6.12{\times}10^{-7}$, $1.04{\times}10^{-6}$ and $6.92{\times}10^{-7}[A/cm^2]$, respectively. Corrosion tends to occur preferentially Cr and B rich area.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.1
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• pp.35-41
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• 1998

This study was carried out to investigate the development rates of human embryos co-cultured with cumulus cells to each blastocyst stage. Human zygotes were co-cultured on cumulus cell monolayer in YS medium supplemented with 20% hFF. On day 2, if patient had four or more "good" embryos (regular blastomeres without fragmentation), embryos were further cultured for 72hrs. Blastocysts on day 5 were classified into early blastocyst (ErB), early expanding blastocyst (EEB), middle expanding Blastocyst (MEB), and expanded blastocyst (EdB) on the basis of their morphological aspects of trophectoderm cells and blastocoele. Subsequently, maximum 3 of best blastocysts were transferred in 486 cycles. The results in this study were as follows: Patients who had four or more "good" embryos on day 2 were 498 persons, but patients whose embryos could not be transferred due to failure in development to the blastocyst stage on day 5 were 12 persons (2.4%). The development rate of embryos to the blastocyst stage was 58.2% (2,885/4,957) on day 5, and the rates that developed to the ErB, EEB, MEB, and EdB stage were 15.0% (743/4,957), 14.9% (739/4,957), 14.4% (714/ 4,957), and 13.9% (689/4,957), respectively. Total 1366 blastocysts were transferred in 486 cycles (mean number=2.81). The implantation rate and the ongoing implantation rate obtained by observing the number of G-sac and FHB were 29.9% (409/1,366) and 22.5% (308/1,366), respectively. The clinical pregnancy rate was 51.2% (249/486), and the ongoing pregnancy rate' was 39.1% (190/486). Among women showing ongoing pregnancy, women with singleton were 50% (95/190), women with twin were 37.9% (72/190), and women with triplet were 12.1% (23/190). Although triplet pregnancy rate in this study was high such as 12.1%, because many blastocysts with high viability were produced in our co-culture system using cumulus cells on day 5, we really believe that a multiple pregnancy except twin should not occur by selecting good embryos for maximum two blastocyst transfer. These results demonstrate that autologous cumulus cells may be used for the production of blastocysts with high developmental competence, and the use of autologous cumulus cells to be collected easily, and to be treated conveniently at OPU must be an effective means for obtaining high implantation and pregnancy rate.

• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.324-327
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• 2009

A new sprout-soybean cultivar, "Galchae" was developed at the National Institute of Crop Science (NICS) in 2008. Galchae was selected from a cross between YS1287 and Jinju#1. The preliminary, advanced, and regional yield trials to evaluate the performance of Iksan 64 were carried out from 2005 to 2008. This cultivar has a determinate growth habit with purple flower, brown pubescence, brown seed coat, brown hilum, rhomboid leaflet shape and small seed size (8.4 grams per 100 seeds). The maturity date of "Galchae" is 6 days later than the check variety, "Dawon". It has good seed quality for soybean-sprout and resistance to lodging. This cultivar has resistance to soybean mosaic virus (SMV) and necrotic symptom (SMV-N). The average yield of "Galchae" was 2.51 ton per hectare in the regional yield trials (RYT) for double cropping carried out for two years from 2007 to 2008.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.267-271
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• 2010

A new black seed coat soybean cultivar, 'Daeheug', was developed at the National Institute of Crop Science (NICS) in 2007. The breeding goal for black seed coat soybean is to develop the cultivar with large seed size, high yield, lodging tolerance, and resistance to disease such as soybean mosaic virus (SMV), and bacterial pustule. 'Daeheug' was selected from the cross between 'Daehwang' which had yellow seed coat, large seed size, and late maturity, and 'Milyang 79' which was lodging tolerant, and SMV resistant with medium seed size, black seed coat, and yellow cotyledon. The preliminary, advanced and regional yield trials for evaluation and selection of this cultivar were carried out from 2003 to 2007. It has determinate growth habit, purple flower, brown pubescence, brown pod color, black seed coat, yellow cotyledon, spherical flattened seed shape, oval leaf shape and large seed size (34.3 g/100 seeds). In maturity, 'Daeheug' was 2 days later than the check cultivar 'Ilpumgeomjeongkong'. In the seed quality such as isoflavone contents ($635{\mu}g/g$), and anthocyanin contents ($11.2m{\ell}/g$ of seed coat), 'Daeheug' was better than the check cultivar. It has good adaptability for cooking with rice in ratio of water absorption and seed hardness. Specially, it has good processability for soybean tea with 2.13 absorbance at 530 nm, scavenge activity of DPPH radical was high, and contents of total phenolics was $1,263{\mu}g/m{\ell}$. The average yield of 'Daeheug' was 2.26 ton per hectare in the regional yield trials (RYT) carried out in six locations of Korea from 2005 to 2007.