• Journal of Welding and Joining
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• v.15 no.1
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• pp.101-108
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• 1997

In repaired weldment of ASTM A-470 class 8 high pressure stream turbine rotor steel, creep rupture life was studied in relation with carbide morphology. Carbides were identified using carbide extraction replica method. A retired rotor has molybdenum rich carbide $M_2C$, lndacochea vanadium rich carbide $M_4C_3$, and chromium rich carbides $M_{23}C_6$and $M_7C_3$. Weldments ruptured at ICHAZ showed that some of carbides have been transformed into spherical types of coarsened carbides at ruptured area. Those carbides were revealed as molybdenum rich $M_6C$ carbide and they provided cavitation sites due to molybdenum depletion around $(M_6C)$ carbide. However coarsened $M_6C$ and $M_{23}C_6$ carbides were observed at ruptured area in case of ruptured at CGHAZ.

• Journal of the Korean Ceramic Society
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• v.36 no.11
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• pp.1261-1265
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• 1999

Effect of SiC particle size of the densification of Al2O3-SiC composite during pressureless sintering was investigated. Two types of SiC powders having average particle size of 0.15${\mu}{\textrm}{m}$ and 3${\mu}{\textrm}{m}$ were used. Densification rate of the specimen containing 0.15${\mu}{\textrm}{m}$ SiC particles was slower than that of the specimen containg 3${\mu}{\textrm}{m}$ SiC particles. Although the relative density of the specimen containing 0.15${\mu}{\textrm}{m}$ SiC particles was below 90% of theoretical density after sintering at 155$0^{\circ}C$ the complete closure of open pores occurred. Therefore full densification could be obtained by subsequent HIP. On the other hand in the specimen containing 3${\mu}{\textrm}{m}$ SiC particles the complete closed pore was observed at 95% of theoretical density. Such a fast pore closure in the specimen containing 0.15${\mu}{\textrm}{m}$ SiC particles is likely to occur as a result of dense reaction layer formation on the specimen surface which is attributed to the high reactivity of small size particles with sintering atmosphere.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.24-30
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• 2003

A formation and conversion of AFm phases decisively play role in the hydration, hardening and corrosion processes of various cement. In this study, the conversion of Alumino-Ferrite Monohydrates(AFm) phases under the addition of $CaCO_3,;CaCl_2;and;CaSO_4{cdot}2H_2O$was investigated by the XRD quantitative analysis. The thypical AFm phases are $M_S(monosulfoaluminate),;M_C(monocarboaluminate);and;M_{Cl}(monochloroaluminate and also Called Friedel's salts)$in this cementitious system, The conversion reaction were not occurred in $M_C-CaCO_3,;M_{Cl}-CaCO_3$ and $M_{Cl}-CaCl_2$system. However, in $M_S-CaCO_3$ system, ettringite and $monocarboaluminate(M_C)$ were formed. In $M_S-CaCl_2;system;M_S$ was transformed to Friedel's $salts(M_{Cl})$ and ettringite was formed. In the case of $CaSO_4{cdot}2H_2O$ addition, all AFm $phases(M_S,;M_C;and;M_{Cl})$ were transformed to ettringite. The order of stabilization of AFm phases under $CaCO_3,;CaCl_2;and;CaSO_4{cdot}2H_2O$ was as follows : $M_S< M_C

• Korean Journal of Microbiology
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• v.25 no.2
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• pp.94-102
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• 1987

Rat liver LDH A-cDNA has been isolated from a .lambda.gt11-rat lover cDNA library and partially characterized. The size of the isolated rat liver LDH A-cDNA if shown to be 1.6Kb and restriction enzyme sites for the rat liver LDH A-cDNA are also mapped. 682-nucleotide sequence coding for 3'-end of rat liver LDH A-cDNA has been analyzed and compared to the nucleotide sequence of the same region of rat $C_6$-glioma cell LDH A-cDNA which has been cloned from the hormonally stimulated cell cultures. The result shows that 177 nucleotide sequences coding for the C-terminal 59-amino acids are identical but 505 nucleotide sequences of 3'-nontranslated region of the two LSH A-cDNA exhibit characteristic differences in thier nucleotide sequences. Computer analysis for the folding structures for 3'-end 400 nucleotide sequences of the two LDH A-cDNA shows a possibility implying that the two LDH A-mRNAs isolated from different tissues of rats may have different half life and therefore their translational efficiency may be different. It has been previously demonstrated that isoproterenol stimulated rat $C_6$ -glioma cell cultures produce LDH A-mRNA showing 2 to 3-fold longer half life in comparison to that of noninduced LHD A-mRNA. The result therefore support for the idea that hormonally stimulated rat $C_6$-glioma cells may produce LDH A-mRNA containing different nucleotide sequences at the 3'-end nontranslated region by which the hormonally induced LDH A-mRNA could have more stable secondary mRAN structure in comparison to that of noninduced LDH A-mRNA.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.181-198
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• 1998

In order to determine the optimum pasteurization conditions by microwave heating(MWH) at $50^{\circ}C{\sim}70^{\circ}C$ for 30 minute compared with water bath heating(WBH) at $65^{\circ}C$ for 30minute during storage at $5^{\circ}C$, the chemical composition, microbiological changes and keeping quality were examined and the results were as follows: 1. The fat protein lactose, total solid contents of raw milk, at $50{\sim}70^{\circ}C$ for 30 min. in MWH and at 65 for $30^{\circ}C$ min. in WBH did not changed significantly during the storage at $5^{\circ}C$. 2. The pH and acidity for the raw milk untreated were 6.75 and 0.16%, and those of MWH heated and WBH milk wee 6.75~6.50 and 0.16%~0.19%, phosphatase test were negative at $61^{\circ}C$ for 20 min. at $62^{\circ}C$ for 15 min. at $63^{\circ}C$ for 10 min. at $64^{\circ}C$ for 5 min. at $65^{\circ}C$ for 5 min. in MWH and at $65^{\circ}C$ for 30 min. in WBH. 3. Whey protein content was $18.53mg/m{\ell}$ in raw milk untreated, however, those were decreased as the heating temperature increased. The proteolytic activity of treated milk by WBH(44%) was lower than that by MWH(94%). 4. Total bacteria counts were $2.8{\times}10^5CFU/m{\ell}$ in raw milk untreated, $2.8{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. $2.4{\times}10^3CFU/m{\ell}$ at $70^{\circ}C$ for 30 min. in MWH and $3.0{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. in WBH. Because total bacteria count did not increased in MWH at $65^{\circ}C$, $70^{\circ}C$ for 30 min. and $65^{\circ}C$ for 30 min. in WBH during the 10 days storaging, Also, total bacteria counts for treated milk were a most drastic decrease after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH. 5. Coliform bacteria counts were $2.6{\times}10^3CFU/m{\ell}$ in raw milk untreated. There were not detected at $55^{\circ}C{\sim}70^{\circ}C$ for 30 min. in MWH and at $65^{\circ}C$ for 30 min. in WBH. Coliform bacteria counts were not detected after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH. 6. Thermoduric bacteria counts were $5.2{\times}10^4CFU/m{\ell}$ in raw milk untreated, $2.0{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. $1.9{\times}10^3CFU/m{\ell}$ at $70^{\circ}C$ for 30min. in MWH and $2.2{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. in WBH. Because thermoduric bacteria counts did not increased in MWH at $65^{\circ}C$, $70^{\circ}C$ for 30 min. and $65^{\circ}C$ for 30 min. in WBH during the 10days storaging. Also, thermoduric bacteria counts were a most drastic decrease after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH. 7. Psychrotrophic bacteria counts were $2.8{\times}10^5CFU/m{\ell}$ in raw milk untreated, $2.0{\times}10^1CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. $2.0{\times}10^1CFU/m{\ell}$ at $70^{\circ}C$ for 30 min. in MWH and $3.0{\times}10^1CFU/m{\ell}$ at $65^{\circ}C$for 30 min. in WBH. Because psychrotrophic bacteria counts did not increased in MWH at $65^{\circ}C$, $70^{\circ}C$ for 30min. and $65^{\circ}C$ for 30 min. in WBH during the 10 days storaging. Also, psychrotrophic bacteria counts were a most drastic decrease after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.321-326
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• 2000

To compare germinability of primed seeds with that of water imbibed and nonprimed seeds at different temperatures, percent germination, number of days to attain 50% of the final germination percentage (T50) and mean number of days to germination (MDG) were evaluated at various temperatures ranged from $10^{\circ}C$ to $35^{\circ}C$. Primed carrot seeds in -0.50 MPa PEG 8000 showed higher percent germination at $10^{\circ}C$ or $35^{\circ}C$. Reductions in T50 and MDG values were observed at all germination temperatures when primed with the PEG. The PEG combined with 100 mM $K_3PO_4$ was not as effective as the PEG alone in improving the germinability of carrot seeds. Nonprimed lettuce seeds germinated only 2% at $30^{\circ}C$ or $35^{\circ}C$. However, priming with 50 mM $K_3PO_4$ increased germination to 40% at $30^{\circ}C$ and to 21% at $35^{\circ}C$. In contrast to the single treatment of 50mM $K_3PO_4$, priming lettuce seeds in a mixture of 50mM $K_3PO_4$ and 200 mM $KH_2PO_4$ resulted in a lower percentage of germination, but a significant greater reduction of T50 and MDG. Percent germination was increased when 200 mM $KH_2PO_4$-primed onion seeds and 100 mM $Ca(NO_3)_2$-primed Welsh onion seeds were germinated at $10^{\circ}C$ or $35^{\circ}C$. Combined treatments with $Ca(NO_3)_2$ for onion and with $KH_2PO_4$ for Welsh onion seeds did not improve percent germination, but they significantly reduced T50 and MDG.

• Journal of Sensor Science and Technology
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• v.16 no.2
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• pp.85-90
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• 2007

This paper presents the growth conditions and characteristics of polycrystalline 3C-SiC (silicon carbide) thin films for M/NEMS applications related to harsh environments. The growth of the 3C-SiC thin film on the oxided Si wafers was carried out by APCVD using HMDS (hexamethyildisilane: $Si_{2}(CH_{3})_{6})$ precursor. Each samples were analyzed by XRD (X-ray diffraction), FT-IR (fourier transformation infrared spectroscopy), RHEED (reflection high energy electron diffraction), GDS (glow discharge spectrometer), XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscope) and TEM (tunneling electro microscope). Moreover, the electrical properties of the grown 3C-SiC thin film were evaluated by Hall effect. From these results, the grown 3C-SiC thin film is very good crystalline quality, surface like mirror and low defect. Therefore, the 3C-SiC thin film is suitable for extreme environment, Bio and RF M/NEMS applications in conjunction with Si fabrication technology.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.317-322
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• 2016

While PFOS sodium salt ($C_8F_{17}SO_3Na$) was not degraded by microorganisms for 28 days, the 4 alternatives were biodegraded at the rates of 21.6% for $C_{25}F_{17}H_{32}S_3O_{13}Na_3$, 20.5% for $C_{15}F_9H_{21}S_2O_8Na_2$, 15.8% for $C_{23}F_{18}H_{28}S_2O_8Na_2$ and 6.4% for $C_{17}F_9H_{25}S_2O_8Na_2$, respectively. The acute toxicity test using Daphnia magna was conducted for 48 hours, the half effective concentration ($EC_{50}$) of PFOS sodium salt ($C_8F_{17}SO_3Na$) was evaluated in 54.5 mg/L. While the 4 alternatives did not show any effect at 500.0 mg/L. The surface tension of the PFOS salt ($C_8F_{17}SO_3Na$) is 46.2 mN/m at a concentration of 500.0 mg/L. While the surface tension of the 4 alternatives was found to be superior to PFOS sodium salt ($C_8F_{17}SO_3Na$). The surface tension of $C_{23}F_{18}H_{28}S_2O_8Na_2$ (20.9 mN/m) has the lowest, followed by $C_{15}F_9H_{21}S_2O_8Na_2$ (23.4 mN/m), $C_{17}F_9H_{25}S_2O_8Na_2$ (27.3 mN/m), $C_{25}F_{17}H_{32}S_3O_{13}Na_3$ (28.2 mN/m). The four kinds of alternatives ($C_{15}F_9H_{21}S_2O_8Na_2$, $C_{17}F_9H_{25}S_2O_8Na_2$, $C_{23}F_{18}H_{28}S_2O_8Na_2$, $C_{25}F_{17}H_{32}S_3O_{13}Na_3$) were found to be superior to PFOS sodium salt ($C_8F_{17}SO_3Na$) in terms of biodegradation, Daphnia sp. acute toxicity and surface tension, and thus they were considered applicable as PFOS alternatives. Especially biodegradation rate of $C_{15}F_9H_{21}S_2O_8Na_2$, $C_{23}F_{18}H_{28}S_2O_8Na_2$ and $C_{25}F_{17}H_{32}S_3O_{13}Na_3$ was relatively high as 15.8~21.6%, and Daphnia sp. acute toxicity and surface tension were considerably superior (surface tension 39~55%) to PFOS sodium salt. Therefore, these alternatives are considered to be available as an alternative of PFOS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.217-217
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• 2009

This paper describes the characteristics of polycrystalline 3C-SiC doubly clamped beam micro resonators. The polycrystalline 3C-SiC doubly clamped beam resonators with 60 ~ 100 ${\mu}m$ lengths, $10\;{\mu}m$ width, and $0.4\;{\mu}m$ thickness were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and their fundamental resonant frequency was measured by a laser vibrometer in vacuum at room temperature. For the 60 ~ 100 ${\mu}m$ long cantilevers, the fundamental frequency appeared at 373.4 ~ 908.1 kHz. The resonant frequencies of doubly clamped beam with lengths were higher than simulated results because of tensile stress. Therefore, polycrystalline 3C-SiC doubly clamped beam micro resonators are suitable for RF MEMS devices and bio/chemical sensor applications.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.149-156
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• 1999

Steroid hormone is known to cause the dynamic changes of mammalian uterus during reproductive cycle, which are modulated via hypothalamus-pituitary -gonad reproductive endocrine axis. Although there were so many studies about estrogenic regulation of uterine growth and differentiation. There is little information about the effect of estrogen on the expression of various transcription factors involved in gene expression. Thus the present study was designed to demonstrate E induced expression of c-fos, c-jun, hsp25 mRNA in rat uterus. Employing Northern blot analysis, we studied the temporal expressions of c-fos, c-jun, and hsp25 messenger RNAs (mRNAs) elicited by a single 17beta-estradiol (E) treatment in the uteri of bilaterally ovariectomized adult rats. c-fos, c-jun, and hsp25 mRNA levels were increased and peaked at 3h after E administration, and then c-fos and c-jun mRNA levels were rapidly decreased to basal control level while, increased hsp25 mRNA levels were sustained till 12h post E treatment. To test the estrogenic effect on the increase of c-fos, c-jun, and hsp25 mRNA levels, we also examined the effects of antiestrogen (tamoxifen). Pretreatment with tamoxifen effectively blocked the E-induced increase of c-fos, c-jun, and hsp25 mRNA levels at 3h post E treatment. Present results suggest that transient increase of c-fos and c-jun protooncogene mRNA at the early time and simultaneous expression of hsp25 mRNA contribute to the response of uterine tissues to E in adult female rats.