• Korean Journal of Metals and Materials
• /
• v.49 no.4
• /
• pp.275-280
• /
• 2011

This paper focuses on reliability prediction of long-term creep strength for Modified 9Cr-1Mo steel (Gr. 91) which is considered as one of the structural materials of next generation reactor systems. A "Z-parameter" method was introduced to describe the magnitude of standard deviation of creep rupture data to the master curve which can be plotted by log stress vs. The larson-Miller parameter (LMP). Statistical analysis showed that the scattering of the Z-parameter for the Gr. 91 steel well followed normal distribution. Using this normal distribution of the Z-parameter, the various reliability curves for creep strength design, such as stress-time temperature parameter reliability curves (${\sigma}$-TTP-R curves), stress-rupture time-reliability curves (${\sigma}-t_{r}-R$ curves), and allowable stress-temperature- reliability curves ([${\sigma}$]-T-R curves) were reasonably drawn, and their results are discussed.

• Transactions of the KSME C: Technology and Education
• /
• v.4 no.2
• /
• pp.101-109
• /
• 2016

The material properties of heat resistant materials at power plants are affected by thermal aging as operating time is accumulated. In this study, the influence of thermal aging on yield strength, tensile strength and fracture behavior for Mod.9Cr-1Mo (ASME Grade 91) steel which is a material widely adopted for Generation IV nuclear energy system has been investigated and analyzed. Service exposed Gr.91 steel materials sampled from a piping system of an ultra-supercritical (USC) plant in Korea with accumulated operation time of 73,716 hours were used for material testing. The test results of the service exposed material specimens were compared with those of the virgin Gr.91 steel specimens. Those test data were compared with the material properties of ASME code and RCC-MRx code. Conservatisms of the material properties in the design codes have been quantified based on the comparisons of those from virgin and service exposed material specimens.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1105-1110
• /
• 2011

After pure titanium Ingot(G2) with 400mm in diameter was manufactured, the analysis of its ingredients showed that the oxygen content was 0.073wt% and the iron content was 0.03wt%, which made ASTM Gr.2 standardization satisfactory. The processed titanium ingot produced 42mm wire rod, and hot rolling of 18th phase produced 9mm wire rod. The hardness analysis of 15.8mm wire rod, which was processed in hot rolling of 10th phase from the surface to the center, resulted in almost constant value with Hv150~200. The last 9mm wire rod had a different yield strength and elongation percentage depending on the temperature as it was led in to a hot roller. However, tensile strength revealed an approximate value and made ASTM B863 standardization satisfactory.

• BMB Reports
• /
• v.46 no.9
• /
• pp.454-459
• /
• 2013

LRRK2 (leucine-rich repeat kinase 2) has been identified as a gene corresponding to PARK8, an autosomal-dominant gene for familial Parkinson's disease (PD). LRRK2 pathogenic-specific mutants induce neurotoxicity and shorten neurites. To elucidate the mechanism underlying LRRK2 expression, we constructed the LRRK2-promoter-luciferase reporter and used it for promoter analysis. We found that the glucocorticoid receptor (GR) transactivated LRRK2 in a ligand-dependent manner. Using quantitative RT-PCR and Western analysis, we further showed that treatment with dexamethasone, a synthetic GR ligand, induced LRRK2 expression at both the transcriptional and translational levels, in dopaminergic MN9D cells. Dexamethasone treatment also increased expression of ${\alpha}$-synuclein, another PD causative gene, and enhanced transactivation of the ${\alpha}$-synuclein promoter-luciferase reporter. In addition, dexamethasone treatment to MN9D cells weakly induced cytotoxicity based on an LDH assay. Because glucocorticoid hormones are secreted in response to stress, our data suggest that stress might be a related factor in the pathogenesis of PD.

• The Korea Journal of Herbology
• /
• v.23 no.3
• /
• pp.155-162
• /
• 2008

Objectives : This study was evaluated to elucidate the inhibitory potential of Bodusan (BDS) and its components, Strychnos ignatii semen (SIS) and Glycyrrhizae Radix (GR), on human aortic smooth muscle cells (HASMC) migration and production of matrix metalloproteinase (MMP)-2 and MMP-9 by $TNF-{\alpha}$ treatment. Methods : Cytotoxic activity of BDS and its components on HASMC was using 5-(3-caroboxymeth- oxyphenyl)-2H-tetra-zolium inner salt (MTS) assay. Effect of BDS, SIS and GR on $TNF-{\alpha}-induced$ HASMC migration underside of matrigel filter was stained with hematoxylin-eosin. And total number of cells that migrated to the underside of the filter was counted. MMP-2 and MMP-9 activity was evaluated by gelatin zymography assay. Results : The matrigel migration assay showed that BDS effectively inhibited the $TNF-{\alpha}-induced$ migration of HASMC. Moreover, BDS significantly inhibited MMP-9 activity. Our present study demonstrates that BDS and its components inhibits $TNF-{\alpha}-induced$ HASMC migration and MMP-9 activity. The inhibitory effect of BDS extract is more potent than that of its component herb extracts. Conclusions : These results provide evidence that BDS has multiple effects in the inhibition of HASMC migration and may offer a therapeutic approach to block HASMC migration.

• Tuberculosis and Respiratory Diseases
• /
• v.85 no.2
• /
• pp.147-154
• /
• 2022

Background: The expression of calcium signaling pathway molecules is altered in various carcinomas, which are related to the proliferation and altered characteristics of cancer cells. However, changes in calcium signaling in anti-cancer drug-resistant cells (bearing a T790M mutation in epidermal growth factor receptor [EGFR]) remain unclear. Methods: Afatinib-mediated changes in the level of store-operated Ca²⁺ entry (SOCE)-related proteins and intracellular Ca²⁺ level in non-small cell lung cancer cells with T790M mutation in the EGFR gene were analyzed using western blot and ratiometric assays, respectively. Afatinib-mediated autophagic flux was evaluated by measuring the cleavage of LC3B-II. Flow cytometry and cell proliferation assays were conducted to assess cell apoptosis and proliferation. Results: The levels of SOCE-mediating proteins (ORAI calcium release-activated calcium modulator 1 [ORAI1], stromal interaction molecule 1 [STIM1], and sarco/endoplasmic reticulum Ca²⁺ ATPase [SERCA2]) decreased after afatinib treatment in non-small cell lung cancer cells, whereas the levels of SOCE-related proteins did not change in gefitinib-resistant non-small cell lung cancer cells (PC-9/GR; bearing a T790M mutation in EGFR). Notably, the expression level of SOCE-related proteins in PC-9/GR cells was reduced also responding to afatinib in the absence of extracellular Ca²⁺. Moreover, extracellular Ca²⁺ influx through the SOCE was significantly reduced in PC-9 cells pre-treated with afatinib than in the control group. Additionally, afatinib was found to decrease the level of SOCE-related proteins through autophagic degradation, and the proliferation of PC-9GR cells was significantly inhibited by a lack of extracellular Ca²⁺. Conclusion: Extracellular Ca²⁺ plays important role in afatinib-mediated autophagic degradation of SOCE-related proteins in cells with T790M mutation in the EGFR gene and extracellular Ca²⁺ is essential for determining anti-cancer drug efficacy.

• Korean Journal of Animal Reproduction
• /
• v.25 no.2
• /
• pp.155-162
• /
• 2001

These experiments were conducted to evaluate the effects of the administration of exogenous PG $F_{2{\alpha}}$ on hormone concentrations and follicular development in early postpartum(pp) Korean native goats. 1. Plasma PG $F_{2{\alpha}}$ concentrations in PG $F_{2{\alpha}}$ treated goals showed a gradual increase from a low on day 2 (GR-1 : 10 day-treatment group: 6.35$\pm$0.5 and GR-2; 4 day-treatment group: 0.22$\pm$0.2 pg/$m\ell$, respectively) to reach a peak of 21.18$\pm$1.6 or 4.21 $\pm$0.4 pg/$m\ell$ on day 4 after treatment of PG $F_{2{\alpha}}$. 2. Plasma PG $F_{2{\alpha}}$ concentrations in GR-1 goats averaged 9.08 $\pm$1.2 pg/$m\ell$ compared with 5.44$\pm$ 1.8 pg/$m\ell$ in GR-2 goats the day before treatment of PG $F_{2{\alpha}}$. Mean PG $F_{2{\alpha}}$ concentrations thereafter remained low during the treatment period but PG $F_{2{\alpha}}$ concentrations did not differ between the two group. 3. Plasma concentrations of estradiol-17 $\beta$ (E,) in PG $F_{2{\alpha}}$ - treated group were decreased gradually until 2 days after PG $F_{2{\alpha}}$ treatment but mean $E_2$ concentrations began to increase on 3 days and were Inaximal on the 4 days after treatment. 4. Plasma lulenizing hormone (LH) concentrations in PG $F_{2{\alpha}}$ - treated goats were slightly higher than in controls but mean LH concentrations did not differ between the two treatment groups. 5. Plasma prolactin (PRL) concentrations were suppressed in both GR-1(10 day-treatment group) and GR-2(4 day-treatment group) goats compared to saline controls but mean PRL concentrations remained lower in PG $F_{2{\alpha}}$ treated animals during post-treatment period. 6. The mean number of small and medium follicles present when PG $F_{2{\alpha}}$ was administrated was similar in all does but the increase in number of large follicles($\geq$4mm) tended to be higher in PG $F_{2{\alpha}}$ treated group than controls. These results suggest that concentrations of PG $F_{2{\alpha}}$ and estradiol-17$\beta$ were positively correlared with follicular diameter. We conclude that PG $F_{2{\alpha}}$ treatment stimulates follicular development similarly in both GR-1 and GR-2 group.

• The Korean Journal of Nuclear Medicine
• /
• v.37 no.2
• /
• pp.83-93
• /
• 2003

Background: Lung-to-heart uptake ratio (LHR) in $^{201}Tl-chloride$ myocardial perfusion scan is believed to be a reliable marker for left ventricular (LV) dysfunction, but the clinical value of LHR is controversial for $^{99m}Tc-MIBI$ imaging. Furthermore, most of results suggesting lung uptake of $^{99m}Tc-MIBI$ as a potential marker for LV dysfunction used immediate post-stress images, instead of routine images acquired 1 hour after tracer injection. The goal of our study was to investigate whether LHR evaluated with routine gated $^{99m}Tc-MIBI$ imaging can reflect the degree of perfusion defect or left ventricular performance. Subjects and Methods: 241 patients underwent exercise $^{99m}Tc-MIBI$ myocardial SPECT were classified into normal myocardial perfusion (NP, n=135) and abnormal myocardial perfusion (AP, n=106) group according to the presence of perfusion defect. LHR was calculated from anterior projection image taken at 1-hour after injection. Two legions of interest (ROIs) were placed on left lung above LV and on myocardium showing the highest radioactivity. Subjects were classified by left ventricular ejection fraction (LVEF), as Gr-I: >50%, Gr-II: 36-50%, Gr-III: <36% and by summed stress score (SSS), as Gr-A: <4, Gr-B: 4-8, Gr-C: 9-13, Gr-D: >13, LHR was compared among these groups. Results: In NP group(n=135), LHR, were higher in men than women ($men:\;0.311{\pm}0.03,\;women:\;0.296{\pm}0.03,\;p<0.05$). Significant difference, in LHR were found between NP and AP groups both for men and women ($men:\;0.311{\pm}0.03\;vs\;.\;0.331{\pm}0.06,\;women:\;0.296{\pm}0.03\;vs.\;0.321{\pm}0.07.\;p<0.05$). There were weak negative correlation between LHR and LVEF (r=-0.342, p<0.05) and weak positive correlation between LHR and SSS (r=0.478, p<0.05) in men, but not in women (LVEF: r=-0.279, p=0.100, SSS: r=0.276, p=0.103). Increased LHR was defined when for more than mean + 2SD value ($men{\geq}0.38,\;women{\geq}0.37$) of the LHR of the subject with normal perfusion. Increased LHR were observed more frequently in subjects with lower LVEF (Gr-I: 11.1%, Gr-II: 27.0%, Gr-III: 35.4%, p<0.05) and higher SSS(Gr-A: 14.0%, Gr-B: 5.7%, Gr-C: 18.2%, Gr-D: 40.7%, p<0.05). Conclusions: LHRs obtained from routine $^{99m}Tc-MIBI$ gated SPECT images were weakly correlated with LVEF and perfusion defect. Although significant overlaps were observed between normal and abnormal perfusion group, LHRs could be used as an indirect marker of severe perfusion defect or reduced left ventricular function.

• Corrosion Science and Technology
• /
• v.2 no.1
• /
• pp.41-46
• /
• 2003

Flow-Accelerated Corrosion behavior concerning both activation and mass transfer process of SA106 Gr.C steel was studied using rotating cylinder electrode in room temperature alkaline solution by DC and AC electrochemical techniques. Passive film was tanned from pH 9.8 by step oxidation of ferrous product into hydroxyl compound. Corrosion potential shifted slightly upward with rotating velocity through the diffusion of cathodic species. Corrosion current density increased with rotating velocity in pH 6.98, while it soon saturated from 1000 rpm at above pH 9.8. On the other hand the limiting current increased with rotating speed regardless of pH values. It seems that activation process, which represents formation of passive film on the bare metal surface, controls the entire corrosion kinetics

• Nuclear Engineering and Technology
• /
• v.32 no.6
• /
• pp.595-604
• /
• 2000

Flow-Accelerated Corrosion Behavior of SA106 Gr.C steel in room temperature alkaline solution simulating the CANDU primary water condition was studied using Rotating Cylinder Electrode. Systems of RCE were set up and electrochemical parameters were applied at various rotating speeds. Corrosion current density decreased up to pH 10.4 then it increased rapidly at higher pH. This is due to the increasing tendency of cathodic and anodic exchange half-cell current. Corrosion potential shifted slightly upward with rotating velocity. Passive film was formed from pH 9.8 by the mechanism of step oxidation and the subsequent precipitation of ferrous species into hydroxyl compound. Above pH 10.4, the film formation process was active and the film became stable. Corrosion current density showed increment in pH 6.98 with the rotating velocity, while it soon saturated from 1000 rpm above pH 9.8. This seems that activation process which represents formation of passive film on the bare metal surface controls the entire corrosion process