• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.2146-2150
• /
• 2004

To evaluate the variation of spring stiffness in nuclear plant operating condition, load-displacement tests ($P-{\delta}$ test) were performed using two kinds of space grid springs in high temperature and high pressure water. With increasing temperature, stiffness of each spring gradually decreased except $100{\sim}150^{\circ}C$. It is apparently showed that spring with convex shape had a relatively high stability of spring stiffness at high temperature compared with I-shaped spring. It is suggested that the variation of spring stiffness with temperature and spring shape should be considered as an important variable in the design and analysis of the fuel assembly.

• Journal of the Korean Ceramic Society
• /
• v.26 no.3
• /
• pp.395-401
• /
• 1989

The concentrations of Cu(II), Y(III) and Ba(II) ionic species in aqueous solution due to the formation of Cu2+-oxalate-complex have been theoretically calculated with respect to pH and their solubility diagrams could be obtained. It was verified from the calculation that the excess of Cu2+ and Ba2+ should be added in order to obtain oxalate coprecipitates with the molar ratio of Y : Ba : Cu=1 : 2 : 3. The exact amount of excess species has been calculated with respect to the initial concentrations of metal ions and pH.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.8
• /
• pp.1357-1363
• /
• 2003

This study was conducted to investigate the effect of chicken egg containing IgY against H. pylori in patients with gastritis. Sixty three H. pylori-infected volunteers (20∼43 year, Male Female=49 : 14) were randomized into four groups which were treated with one chicken egg containing IgY b.i.d. (IgY group; n=17) or omeprazole 20 mg b.i.d., amoxicillin 1.0 g b.i.d. and clarithromycin 500 mg b.i.d. (OAC group; n=17) or omeprazole 20 mg b.i.d., amoxicillin 1.0 g b.i.d., clarithromycin 500 mg b.i.d. and one chicken egg containing IgY b.i.d. (OAC with IgY group; n=16) for 2 weeks or lyophilized IgY 1 g b.i.d (lyophilized IgY group) for 1 month. $\Delta$$^{13}$ $CO_2$ before and after treatment, the eradication rate of H. pylori and histologic change including H. pylori density, acute and chronic inflammation activity, intestinal metaplasia and glandular atrophy by updated sydney system were evaluated. Eradication rate of OAC with IgY group (94%) was higher than IgY group (0%), lyophilized IgY group (0%) and OAC group (88%). $\Delta$$^{13}$ $CO_2$at 2 weeks after treatment in one patient of IgY group was decreased. But that was not changed in the other patients. $\Delta$$^{13}$ $CO_2$ at 1 week after treatment in 15 patients of OAC with IgY group was significantly lower than pretreatment level (p<0.05), and $\Delta$$^{13}$ $CO_2$ at 1 week and 2 week after treatment was decreased in the other patient. Acute inflammation activity at antrum was significantly decreased after treatment in IgY and lyophilized IgY group (p<0.01), H. pylori density at antrum was significantly decreased after treatment in IgY and lyophilized IgY group (p<0.05). Chronic inflammation activity at body was decreased after treatment in lyophilized IgY group. Intestinal metaplasia and glandular atrophy at antrum and body were not changed after treatment in IgY group. Mild intestinal metaplasia in one patient of lyophilized IgY group changed to normal after 1 month treatment. Gandular atrophy at antrum and body were not changed after treatment in lyophilized IgY group.

• Journal of Korean society of Dental Hygiene
• /
• v.8 no.3
• /
• pp.13-22
• /
• 2008

Objectives: The purpose of this study was to identify the correlation between calcium in soft drinks and enamel remineralization. Method: Six soft drinks were used in this study. These were calcium milk, normal milk, calcium yoghurt, normal yoghurt, calcium orange juice, and orange juice. Enamel specimens which 300- 400Vickers Hardness Number (VHN) were selected. These samples were immersed in each soft drink for 12 hours in an in vitro remineralization model. All specimens were processed for SEM image of the enamel surface. Results were analyzed by SPSS 13.0 package program. Results: Calcium milk was the most influential and normal yoghurt was the least to enamel surface. There was not significant difference according to calcium supplement in milk although the difference of enamel hardness was ${\Delta}f13.4$ in calcium milk, and ${\Delta}f4.7$ in normal milk (P>0.05). Other soft drinks showed a little change about calcium but they were insignificant. Demineralization effect was remarkably observed in calcium yoghurt ($-{\Delta}f269.1$) and this effect was confirmed by SEM images. In conclusion, calcium supplemented soft drinks had little influences to hardness of enamel surface.

• Progress in Superconductivity
• /
• v.4 no.1
• /
• pp.10-13
• /
• 2002

We report the effect of Ca doping in $YBa_2Cu_3O_{7-\delta}$ (YBCO) thin films grown on the Rolling- Assisted, Biaxially Textured Substrates (RABiTS) with the architecture of $CeO_2/YSZ/CeO_2/Ni$. Critical currents of bilayer and trilayer structures of $YBCO/Y_{0.7}Ca_{0.3}Ba_2Cu_3O_{7-\delta}$/(YCaBCO) as well as undoped YBCO for comparison have been measured in a wide range of temperatures and fields. For $6-8^{\circ}$ grain boundaries, 30% Ca-doping in bilayer structure enhances $J_c$ as high as 35%. The enhancement is larger at low temperatures and at magnetic fields. On the other hand, 30% Ca-doping in trilayer structure reduces $J_c$ as high as 60%. Combined with slightly lower $T_c$, this indicates that Ca is overdoped in this structure and degrades GBs.

• The Journal of Advanced Prosthodontics
• /
• v.3 no.2
• /
• pp.57-62
• /
• 2011

MATERIALS AND METHODS. Ceramics have a long history in fixed prosthodontics for achieving optimal esthetics and various materials have been used to improve ceramic core strength. However, there is a lack of information on how color is affected by fabrication procedure. The purpose of this study was to evaluate the effects of various dentin ceramic thicknesses and repeated firings on the color of zirconium oxide all-ceramic system (LavaTM) fabricated using CAD/CAM technology. MATERIALS AND METHODS. Thirty disc-shaped cores, 12 mm in diameter with a 1 mm thickness were fabricated from zirconium oxide based all ceramic systems ($Lava^{TM}$, 3M ESPE, St Paul, MN, USA) and divided into three groups (n = 10) according to veneering with dentin ceramic thicknesses: as 0.5, 1, or 1.5 mm. Repeated firings (3, 5, 7, or 9) were performed, and the color of the specimens was compared with the color after the initial firing. Color differences among ceramic specimens were measured using a spectrophotometer (VITA Easyshade, VITA Zahnfabrik, Bad $S{\ddot{a}}ckingen$, Germany) and data were expressed in CIELAB system coordinates. A repeated measures ANOVA and Bonferroni post hoc test were used to analyze the data (n = 10, ${\alpha}=.05$). RESULTS. $L^{\ast}a^{\ast}b^{\ast}$ values of the ceramic systems were affected by the number of firings (3, 5, 7, or 9 firings) (P<.001) and ceramic thickness (0.5, 1, or 1.5 mm) (P<.001). Significant interactions were present in $L^{\ast}a^{\ast}b^{\ast}$ values between the number of firings and ceramic thickness (P<.001). An increase in number of firings resulted in significant increase in $L^{\ast}$ values for both 0.5 mm and 1.5 mm thicknesses (P<.01, P=.013); however it decreased for 1 mm thickness (P<.01). The $a^{\ast}$ values increased for 1 mm and 1.5 mm thicknesses (P<.01), while it decreased for 0.5 mm specimens. The $b^{\ast}$ values increased significantly for all thicknesses (P<.01, P=.022). As the dentin ceramic thickness increased, significant reductions in $L^{\ast}$ values (P<.01) were recorded. There were significant increases in both $a^{\ast}$ and $b^{\ast}$ values (P<.01) as the dentin ceramic thickness increased. CONCLUSION. The number of firings and dentin ceramic thickness have a definite effect on the final color of all ceramic system tested. The mean ${\Delta}E$ value increased as the dentin ceramic thicknesses increased for zirconium-oxide based all ceramic specimens tested. However, the mean ${\Delta}E$ values were less than 3.7${\Delta}E$ units which is rated as a match in the oral environment.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.993-1000
• /
• 2006

Practical stability design method of main members of cable-stayed bridges is proposed and discussed through a design example. For this purpose, initial tensions of stay cables and axial forces of main members are firstly determined using initial shaping analysis of bridges under dead loads. And then the effective buckling length using system elastic/inelastic buckling analysis and bending moments considering $P-{\delta}-{\Delta}$ effect by second-order elastic analysis are calculated for main girder and pylon members subjected to both axial forces and moments, respectively. Particularly, load combinations of dead and live loads, in which maximum load effects due to live loads are obtained, are taken into account and effects of live loads on effective buckling lengths are investigated.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.9
• /
• pp.1227-1236
• /
• 2001

A systematic analysis is made of suboptimal control for drag reduction. The influence of the amplitude of actuation (A) and the time scale of actuation ($\Delta$t(sub)a(sup)+) is evaluated. Two wall sensing variables are employed (∂w/∂y│(sub)w and ∂p/∂z│(sub)w) with two wall actuations (${\Phi}$$_2$and ${\Phi}$$_3$). To test the suboptimal control, direct numerical simulations of turbulent channel flow at Re(sub)$\tau$=100 are performed in a spectral domain. It is found that the effect of A and $\Delta$t(sub)a(sup)+∼1. The near-wall behaviors of flow structure are analyzed to characterize the drag reduction. The size effect of the sensor/actuator is examined.

• Journal of the Korean Wood Science and Technology
• /
• v.38 no.5
• /
• pp.414-420
• /
• 2010

The effect of polymeric diphenyl methane-4,4-diisocyanate (pMDI) or 1,6-hexamethylene diisocyanate (HDI) in the UMF resin was discussed for improvement of the dry and wet shear strengths of plywood manufactured from high moisture content veneers. The curing behavior of UMF resin by pMDI or HDI content was examined by DSC and TGA, and its adhesion performance was evaluated by dry and wet shear strength tests of plywood. With the increase of pMDI content in the UMF resin, the curing temperature, reaction enthalpy (${\Delta}H$), and thermal stability consistently increased. With the increase of HDI content in the UMF resin, however, the curing temperature and reaction enthalpy (${\Delta}H$) decreased consistently and the thermal stability slightly increased in the range of 200 to $400^{\circ}C$ but decreased beyond $400^{\circ}C$. Also, the dry tensile shear strength increased up to the pMDI content of 5% and then decreased with its further addition but the wet tensile shear strength showed slight tendency to increase with the increase of pMDI content in the UMF resin. As the HDI content increased, however, the dry and wet tensile shear strengths of plywood consistently increased.

• Journal of dental hygiene science
• /
• v.12 no.4
• /
• pp.342-347
• /
• 2012

This study is a temporary crowns and the period you want to avoid the exposure of the coffee girl polymerization types is difficult given the temporary tolerance by producing resin. 1. Change of brightness ($L^*$) edge in time increases, distilled water, Americano, Cafelatte, Vanillalatte was reduced to a significant level of brightness (p<.001). The most significant decrease in brightness of the Americano, which tend to grow out of a Cafelatte, Vanillalatte, which was followed by distilled water. 2. Change of redness ($a^*$) edge in time tend to increase saturation increases, the redness value of Americano, Cafelatte, redness value was a statistically significant difference in distilled water and Vanillalatte (p<.05) was not significant. 3. Change of yellowness ($b^*$) edge in time tend to increase saturation increases, the yellowness value of Cafelatte, Vanillalatte, Americano, except for distilled water at the saturation of yellowness value were no statistically significant (p<.05). 4. Change of color difference (${\Delta}E^*$) in order of (Americano>Cafelatte>Vanillalatte) as time of immersion increases change of color difference appear and no statistically significant (p<.05). Americano, the edge, since there can be more than chrominance is 3.3 uses station than a Vanillalatte, Cafelatte and discoloration when edge in 28, since even in the one to two difficult to distinguish with the naked eye as a discoloration. It was no difference statistically in color difference (${\Delta}E^*$) value in distilled water (p>.05).