• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.830-834
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• 2004

In this study, lead-free pirzoelectric ceramics were investigated for pressure sensor applications as a function of the amount of ${La}_2{O}_3$ addition at $Bi(Na, K)Ti{O}_3-SrTi{O}_3$system. With increasing the amount of addition, the density and dielectric constant increased up to 0.9 wt% ${La}_2{O}_3$ addition and decreased above 0.9 wt% ${La}_2{O}_3$addition. Electromechanical coupling factor( $K_{P}$) showed the maximum value at 0.2 wt% ${La}_2{O}_3$addition and decreased above 0.2 wt% ${La}_2{O}_3$ addition. Electromechanical coupling $factor{(K)}_P$, density, dielectric constant$(\varepsilon_\Gamma)$, piezoelectric constant$(d_33)$ and curie temperature$(T_C)$ showed optimum value of 0.40, 5.75 g/㎤, 768, 215 pC/N and 320 $^{\circ}C$ at 0.2 wt%${La}_2{O}_3$addition, respectively.

• The Korean Journal of Food And Nutrition
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• v.30 no.1
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• pp.105-111
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• 2017

This study was performed to provide fundamental data on the convenience foods purchase according to the food-related lifestyle. The subject was 250 Chinese students in South Korea region through a self-administered questionnaire. A factor analysis extracted five comprising food-related lifestyle, which we named health seeking (factor 1), taste seeking (factor 2), easy seeking (factor 3), popularity seeking (factor 4) and safety seeking (factor 5). According to the results of the reliability analysis, the food-related lifestyle showed an average of 3.16 and 0.813 for Cronbach's alpha coefficient. There were significant differences for the selection of convenience foods according to health seeking (p<0.05). Also, the popularity seeking and easy seeking lifestyle factors showed significant differences for the reason the purchase criteria of convenience food (p<0.05). There was not significant differences in convenience foods of selection criteria according to health seeking, taste seeking, easy seeking, popularity seeking and safety seeking types (p<0.05). A significant positive result of the internal characteristics of convenience foods purchase (p<0.05) was shown for the health seeking and taste seeking. A significant positive result of the external characteristics of convenience food purchase (p<0.05) was shown for the health seeking, taste seeking and safety seeking. In the correlation between convenience food purchase factors, the correlation coefficient of nutrition and ingredients are highest with 0.46, 0.445 in cooking and price, 0.441 in ingredients and expiry date, 0.383 in brand and price, 0.361 in taste and easy. In conclusion, this study presented the desirable direction of convenience food consumption in Chinese students.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.147-162
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• 2021

The problem of predicting a ship's form factor and associated scale effects has been subject to many investigations in recent years. In this study, an attempt is made to investigate whether the form factor is influenced by a change in the ship's speed by numerically modelling a geosim series of the KCS hull form by means of a RANS solver. The turbulence dependence of the problem is also studied by altering the closure model among three widely used approaches (the k-𝜔, k-𝜔 SST, and k-𝜀 models). The results show that at very low speeds (Froude numbers in the range of 0.02-0.06) the numerical model predicts changes in the form factor of a ship between 10% and 20%, depending on the turbulence model and scale factor choices. As the speed is increased further, the form factor exhibits little change, usually in the range of 1% or less. Simulations where the Reynolds number is changed by approximately two orders of magnitude, achieved by altering the value of viscosity, confirmed that the form factor can be considered Froude-dependent only for low speeds, predicting essentially identical values when high speed cases are considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.959-962
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• 2001

In this study, the piezoelectric and dielectric properties and Temperature stability of resonant frequency with MnO$_2$doped 0.36Pb(Sc$_{1}$2/Nb$_{1}$2/)O$_3$- 0.25Pb(Ni$_{1}$3/Nb$_{2}$3/)O$_3$-0.39PbTiO$_3$(hereafter PSNNT) were investigated. The tetagonality of crystal structure was developed with increasing MnO$_2$additive content. With increasing MnO$_2$additive content, the electromechanical coupling factor and quality factor were increased. Electromechanical coupling k$_{p}$ and quality factor Q$_{m}$ at MnO$_2$doped with 2.0mol% were showed highest value of 55.6% and 252. In the case of specimen for MnO$_2$doped with 2mol%, temperature dependance of resonant frequency had a good properties.ies.

• Journal of IKEEE
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• v.22 no.2
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• pp.384-392
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• 2018

A multiple-output LDO regulator is a good choice in terms of the efficiency in embedded systems requiring various supply voltages. A small feedback factor in LDO incurs the long settling time, resulting in large ripples in the time-multiplexing strategy. A new proposed topology enhances the settling time, and hence the ripples by incorporating the constant feedback factor with different reference voltages. The simulation results of a prototype design in a standard $0.35{\mu}m$ CMOS process verify that the proposed strategy enhances the settling time and ripple characteristic by more than doubled than a conventional circuit using the feedback factor of less than 0.4.

• Transactions on Electrical and Electronic Materials
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• v.11 no.3
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• pp.126-129
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• 2010

(1-X) $(Na_{0.5}K_{0.5})NbO_3-X$ $K_4CuNb_8O_{23}$ (NKN-X KCN) ceramics were produced using the conventional solid state sintering method, and their sinterability and electric properties were investigated. The density, dielectric constant (${\varepsilon}_r$), piezoelectric constant $d_{33}$, electromechanical coupling factor $k_p$ and mechanical quality factor $Q_m$ value of the NKN ceramics depended upon the KCN content and the sintering temperature. In particular, the KCN addition to the NKN greatly improved the mechanical quality factor $Q_m$ value. The ceramic with X = 2.0 mol% sintered at $1,150^{\circ}C$ possesses the optimum properties (${\varepsilon}_r=241$, $d_{33}=78$, $k_p=0.34$ and $Q_m=1,121$). These results indicate that the ceramic is a promising candidate material for applications in lead free piezoelectric transformer and filter materials.

• Journal of the Korean Ceramic Society
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• v.42 no.10 s.281
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• pp.698-702
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• 2005

Dielectric and Piezoelectric properties of complex perovskite 0.92Pb($Zr_{1/2}Ti_{1/2})O_{3}-(0.08-x)Pb(Cu_{1/3}Nb_{2/3})O_{3}-xPb(Mn_{1/3}Nb_{2/3})O_{3}(0{\leq}x{\leq}0.080$) (PZT-PCN-PMN) system were investigated as a function of PMN content. With the increase of PMN content of the sintered specimens, tetragonal phase was coexisted with rhombohedral phase, the dielectric constant was decreased, mechanical quality factor ($Q_{m}$) was inceased, and optimal sintering temperature was increased up to 1050$^{\circ}C$. For the composition of x = 0.064 sintered at 1050$^{\circ}C$ for 2 h, 1939 of maximum mechanical quality factor ($Q_{m}$), 57$\%$ of electromechanical coupling factor ($k_{p}$), and 1100$^{\circ}C$ of dielectric constant, 0.37$\% $ of dielectric loss (tan $\delta$) were obtained.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.152-156
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• 2004

The dielectric and piezoelectric properties of 0.36Pb($Sc_{1/2}Nb_{1/2}$)$O_{3}$-0.25Pb($Ni_{1/3}Nb_{2/3}$)$O_{3}$-0.39Pb$TiO_{3}$ (hereafter PSNNT) at the morphotropic phase boundary (MPB) composition were investigated with $0{\sim}2.5$ mot% $MnO_{2}$ doping. Bulk density, dielectric loss and tetragonality of crystal structure were all improved with increasing $MnO_{2}$ additive content. With increasing $MnO_{2}$ additive content, the electromechanical coupling factor and quality factor were also increased: Electromechanical coupling $k_{p}$ and quality factor $Q_{m}$ at 2.0 mol% $MnO_{2}$ doping with were showed highest values of 55.6 % and 252, respectively.

• Advances in pediatric surgery
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• v.12 no.2
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• pp.202-212
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• 2006

The prognostic factors for extrahepatic biliary atresia (EHBA) after Kasai portoenterostomy include the patient's age at portoenterostomy (age), size of bile duct in theporta hepatis (size), clearance of jaundice after operation (clearance) and the surgeon's experience. The aim of this study is to examine the most significant prognostic factor of EHBA after Kasai portoenterostomy. This retrospective study was done in 51 cases of EHBA that received Kasai portoenterostomy by one pediatric surgeon. For the statistical analysis, Kaplan-Meier method, Logrank test and Cox regression test were used. A p value of less than 0.05 was considered to be significant. Fifteen patients were regarded as dead in this study, including nine cases of liver transplantation. There was no significant difference of survival to age. The age is also not a significant risk factor for survival in this study (Cox Regression test; p = 0.63). There was no significant difference in survival in relation to the size of bile duct. However, bile duct size was a significant risk factor for survival (Cox Regression test; p = 0.002). There was a significant difference in relation to survival and clearance (Kaplan-Meier method; p = 0.02). The clearing was also a significant risk factor for survival (Cox Regression test; p = 0.001). The clearance of jaundice is the most significant prognostic factor of EHBA after Kasai portoenterostomy.

• Biomedical Science Letters
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• v.8 no.4
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• pp.229-234
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• 2002

Chlorella is rich in chlorella growth factor (CGF). A review of the literature has described that CGF improves the capability of a Th1-based immunity, anticancer, antioxidant antibacterial activity, growth promotion, wound healing and so on, but has not studied the effect for the metabolism and the proliferation of human skin keratinocyte. The aim of this study was to examine the effect of metabolism and the proliferation of human skin keratinocyte in vitro. CGF was extracted with an autoclaving method which is a modified hot-water extraction method from dried chlorella and conformed by means of absorbance 0.22 at 260 nm. We have measured the extracellular acidification rate (ECAR) of the CGF by Cytosensor$^{\circledR}$ Microphysiometer and evaluated responsiveness depending upon the dosage on the HaCaT cell. The ECAR for the concentrations of 0.15, 1.5, 15, 150 $\mu\textrm{g}$/ml of CGF increased as a 103.6, 128.2, 149.0 and 423.9%, respectively compared to control (0.0 $\mu\textrm{g}$/ml, 100% ECAR). The ECAR for ErbBl tyrosine kinase inhibited by 4-anilinoquinazolines, $C_{16}$H$_{14}$BrN$_3$O$_2$.HCl on tile HaCaT cells with the amounts of 10 $\mu\textrm{g}$/ml of the CCF compared with 100 $\mu\textrm{g}$/ml of rhEGF. The conclusion of the study is that CGF might increase human epidermal keratinocyte proliferation through the interaction between the epidermal growth factor receptor and itself.