• Clean Technology
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• v.21 no.1
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• pp.68-75
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• 2015

In this study, we investigated the structure and properties of a highly heat conductive metal-ceramic core-shell CoAl₂O₄@Al micro-composite for heterogeneous catalysts support. The CoAl₂O₄@Al was prepared by hydrothermal surface oxidation of Al metal powder, which resulted in the structure with a high heat conductive Al metal core encapsulated by a high surface area CoAl₂O₄ shell. For comparison, CoAl₂O₄ was also prepared by co-precipitation method and also utilized for a catalyst support. Rh catalysts supported on CoAl₂O₄@Al and CoAl₂O₄ were prepared by incipient wetness impregnation and characterized by N₂ adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), CO chemisorption, and temperature-programmed reduction (TPR). The properties of catalysts were investigated for glycerol steam reforming reaction for hydrogen production at 550 ℃. Rh/CoAl₂O₄@Al exhibited about 2.8 times higher glycerol conversion turnover frequency (TOF) than Rh/CoAl₂O₄ due to facilitated heat transport through the core-shell structure. The CoAl₂O₄@Al and CoAl₂O₄ also showed some catalytic activities due to a partial reduction of Co on the support, and a higher catalytic activity was also found on the CoAl₂O₄@Al core-shell than CoAl₂O₄. These catalysts, however, displayed deactivation on the reaction stream due to carbon deposition on the catalysts surface.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.3
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• pp.207-216
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• 2010

Objective: This study was performed to clarify the role of HomeoboxA (HOXA) and its related signaling molecules in the decidualization of primary cultured endometrial cells. Methods: Human endometrial tissues were obtained by curettage of hysterectomy specimens from patients with conditions other than endometrial diseases. Tissues were minced and digested with Trypsin-EDTA for 20 min, $37^{\circ}C$. Cells were cultured with DMEM/F12 medium in $37^{\circ}C$, 5% $CO_2$ incubator for 24 hrs. Cells were treated with HOXA10 siRNA and added transforming growth factor (TGF)-${\beta}1$ (10 ng/mL) for 48 hrs to induces decidualization in vitro. Reverse transcription polymerase chain reaction analysis was accomplished to observe the expression of HOXA10, prolactin, cyclooxygenase (COX)-2, peroxisome proliferatoractivated receptor (PPAR)-$\gamma$, and wingless-type MMTV integration site family (Wnt). Results: HOXA10 expression was increased (1.8 fold vs. non-treated control) in TGF-${\beta}1$ treated cells. Decidualization marker, prolactin, was significantly increased in TGF-${\beta}1$ treated cells compared with HOXA10 siRNA treated cells. Endometrial cell differentiation marker, COX-2 was down-regulated by HOXA10 siRNA even if cells were treated with TGF-${\beta}1$. Wnt4 was down-regulated by treated with HOXA10 siRNA, this expression patters was not changed by TGF-${\beta}1$. Expression of PPAR-$\gamma$ was down regulated by TGF-${\beta}1$ in regardless of HOXA10 siRNA treatment. Conclusion: TGF-${\beta}1$ which is induced by progesterone in endometrial epithelial cells may induces stromal cell decidualization via HOXA10 and Wnt signaling cascade.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.357-365
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• 2016

The effects of elevated atmospheric $CO_2$ on photosynthesis and growth of Chinese cabbage (Brassica campestris subsp. napus var. pekinensis) were investigated to predict productivity in highland cropping in an environment where $CO_2$ levels are increasing. Vegetative growth, based on fresh weight of the aerial part, and leaf characteristics (number, area, length, and width) of Chinese cabbage grown for 5 weeks, increased significantly under elevated $CO_2$ ($800{\mu}mol{\cdot}mol^{-1}$) compared to ambient $CO_2$ ($400{\mu}mol{\cdot}mol^{-1}$). The photosynthetic rate (A), stomatal conductance ($g_s$), and water use efficiency (WUE) increased, although the transpiration rate (E) decreased, under elevated atmospheric $CO_2$. The photosynthetic light-response parameters, the maximum photosynthetic rate ($A_{max}$) and apparent quantum yield (${\varphi}$), were higher at elevated $CO_2$ than at ambient $CO_2$, while the light compensation point ($Q_{comp}$) was lower at elevated $CO_2$. In particular, the maximum photosynthetic rate ($A_{max}$) was higher at elevated $CO_2$ by 2.2-fold than at ambient $CO_2$. However, the photosynthetic $CO_2$-response parameters such as light respiration rate ($R_p$), maximum Rubisco carboxylation efficiency ($V_{cmax}$), and $CO_2$ compensation point (CCP) were less responsive to elevated $CO_2$ relative to the light-response parameters. The photochemical efficiency parameters ($F_v/F_m$, $F_v/F_o$) of PSII were not significantly affected by elevated $CO_2$, suggesting that elevated atmospheric $CO_2$ will not reduce the photosynthetic efficiency of Chinese cabbage in highland cropping. The optimal temperature for photosynthesis shifted significantly by about $2^{\circ}C$ under elevated $CO_2$. Above the optimal temperature, the photosynthetic rate (A) decreased and the dark respiration rate ($R_d$) increased as the temperature increased. These findings indicate that future increases in $CO_2$ will favor the growth of Chinese cabbage on highland cropping, and its productivity will increase due to the increase in photosynthetic affinity for light rather than $CO_2$.

• Restorative Dentistry and Endodontics
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• v.34 no.5
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• pp.450-459
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• 2009

The aim of this study was to measure the initial dynamic modulus changes of light cured composites using a custom made rheometer. The custom made rheometer consisted of 3 parts: (1) a measurement unit of parallel plates made of glass rods, (2) an oscillating shear strain generator with a DC motor and a crank mechanism, (3) a stress measurement device using an electromagnetic torque sensor. This instrument could measure a maximum torque of 2Ncm, and the switch of the light-curing unit was synchronized with the rheometer. Six commercial composite resins [Z-100 (Z1), Z-250 (Z2), Z-350 (Z3), DenFil (DF), Tetric Ceram (TC), and Clearfil AP-X (CF)] were investigated. A dynamic oscillating shear test was undertaken with the rheometer. A certain volume ($14.2\;mm^3$) of composite was loaded between the parallel plates, which were made of glass rods (3 mm in diameter). An oscillating shear strain with a frequency of 6 Hz and amplitude of 0.00579 rad was applied to the specimen and the resultant stress was measured. Data acquisition started simultaneously with light curing, and the changes in visco-elasticity of composites were recorded for 10 seconds. The measurements were repeated 5 times for each composite at $25{\pm}0.5^{\circ}C$. Complex shear modulus G*, storage shear modulus G', loss shear modulus G" were calculated from the measured strain-stress curves. Time to reach the complex modulus G* of 10 MPa was determined. The G* and time to reach the G* of 10 MPa of composites were analyzed with One-way ANOVA and Tukey's test ($\alpha$ = 0.05). The results were as follows. 1. The custom made rheometer in this study reliably measured the initial visco-elastic modulus changes of composites during 10 seconds of light curing. 2. In all composites, the development of complex shear modulus G* had a latent period for $1{\sim}2$ seconds immediately after the start of light curing, and then increased rapidly during 10 seconds. 3. In all composites, the storage shear modulus G" increased steeper than the loss shear modulus G" during 10 seconds of light curing. 4. The complex shear modulus of Z1 was the highest, followed by CF, Z2, Z3, TC and DF the lowest. 5. Z1 was the fastest and DF was the slowest in the time to reach the complex shear modulus of 10 MPa.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.299-303
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• 2008

A thermally cross-linkable polymer, poly[(2,5-dimethoxy-1,4-phenylenevinylene)-alt-(1,4-phenylenevinylene)] (Cross-PPV), was synthesized by the Heck coupling reaction. In order for the polymer to be cross-linkable, 20 mol% excess divinylbenzene was added. The chemical structure of Cross-PPV and thermally crosslinked Cross-PPV were confirmed by FT-IR spectroscopy. From the FT-IR, UV-Vis, and PL spectral data, thermally crosslinked Cross-PPV was insoluble in common organic solvents. The HOMO and LUMO energy level of thermally cross-linked Cross-PPV were estimated -5.11 and -2.56 eV, respectively, which were determined by the cyclic voltammetry and UV-Vis spectroscopy. From the energy level data, one can easily notice that thermally crosslinked Cross-PPV can be used for hole injection layer effectively. Bilayer structured device (ITO/crosslinked Cross-PPV/PM-PPV/Al) was fabricated using poly(1,4-phenylenevinylene-(4-dicyanomethylene-4H-pyran)-2,6-vinylene-1,4-phenylenevinylene-2,5-bis(dodecyloxy)-1,4-phenylenevinylene (PM-PPV) as the emitting layer, which have HOMO and LUMO energy levels of -5.44 eV and -3.48 eV, respectively. The bilayered device had much enhanced the maximum efficiency (0.024 cd/A) and luminescence ($45cd/m^2$) than those of a single layer device (ITO/PM-PPV/Al, 0.003 cd/A, $3cd/m^2$). The enhanced performance originated from that fact that cross-linked Cross-PPV facilitatse the hole injection to the emissive layer and the injected hole and electron from ITO and Al are recombined in emitting layer (PM-PPV) effectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.149-162
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• 2000

Coenzyme Q10 is found in all tissues including skin and it is the well-known coenzyme for mitochondrial enzymes. The electron and proton transfer functions of the quinone ring are of fundamental importance for the oxidative phosphorylation pathway to generate energy in the cells. Coenzyme Q10 has been studied as a potent antioxidant molecule in the skin. It is involved in the skin's response to UVR irradiation. The concentration of this antioxidant in UVR exposed skin is higher than in non-exposed skin. However, recent studies have also shown that coenzyme Q10 is one of the first antioxidants to be depleted when skin is UVR-irradiated. This indicates that coenzyme Q10 is primarily involved in defense mechanisms of the skin. Therefore, we questioned whether coenzyme Q10 shows reulatory effect of melanogenesis. Here we report that coenzyme Q10 inhibits melanin neosynthesis of normal human melanocytes grown in culture, and lightens UVB-induced hyperpigmentation of the guinea pig skin in vivo. We treated human melanocytes with 0.05mM to 0.5mM of coenzyme Q10 for a total of two days. This inhibited melanin neosynthesis of cultured human melanocytes dose-dependently. The inhibitory effect of coenzyme Q10 was as effective as kojic acid or vitamin C on cultured human melanocytes. CoQ10 didn't have direct inhibitory effect on tyrosinase activity in in vitro tyrosine hydroxylase activity To further clarify the effect of coenzyme Q10 on the melanogenesis, we established UVB-induced hyperpigmentation on the shaved backs of brownish guinea pigs. The UVB intensity was 500mJ/$\textrm{cm}^2$ and the total energy dose was 1,500 mJ/$\textrm{cm}^2$. The animals were exposed to UVB radiation one times a week for three consecutive weeks. Coenzyme Q10, kojic acid, Arbutin, vitamin C(1% in vehicle) or vehicle alone as a control were then topically applied daily to the hyperpigmented areas twelve times per week far four successive weeks. The lightening effect was evaluated by visual scoring, chromameter and immunohistochemistry. Coenzyme Q10 had lightening effect on the UVB-induced hyperpigmentation without any other side effects, whereas another compounds showed weak lightening efficacies. Therefore, these results suggest that coenzyme Q10 may be useful for solving physiological hyperpigmenting problems for cosmetic purposes.

• Journal of Life Science
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• v.28 no.12
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• pp.1406-1415
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• 2018

Based on the antioxidative effects in organic solvent fractions obtained from the main methanolic extract of Houttuynia cordata Thunb, the cytoprotective effects by oxidative-stress were here analyzed. Regarding the antioxidant activity of organic solvent fractions, the electron-donating ability of DPPH increased in a dose-dependent manner, and $ED_{50}$ exhibited the highest concentration at $175{\mu}g/ml$ in the Hc-EtOAc fraction. The cell viability of Hc-EtOAc fractions on $H_2O_2$-induced HaCaT cell death ($IC_{50}$) increased in a concentration-dependent manner and a visible cell survival rate of 74% was observed at a concentration of $100{\mu}g/ml$. Meanwhile, the gene expression patterns in HaCaT cells treated with $100{\mu}g/ml$ of the Hc-EtOAc fraction for 6 and 24 hr were identified with microarray analysis. The genes involved in signal transduction, cell division, antioxidant activity, and epithelial cell proliferation were found to be 2-fold up-regulated genes in HaCaT cells following the Hc-EtOAc fraction treatment. Especially, proinflammatory cytokines (IL1B, TNF, and IL6) were identified as involved in antioxidant activity based on the expression patterns of the HaCaT cells, and pathway analysis indicated that TLR4 might be considered an upstream regulator of these genes. In order to verify the activity of IL1B, TNF, and IL6, qRT-PCR showed that the expression increased more than 2 times in HaCaT cells treated with at least $100{\mu}g/ml$ of the Hc-EtOAc fraction. The activity of the upstream regulator TLR4 protein was also increased by the Hc-EtOAc fraction. As a result, the antioxidative activity of the Hc-EtOAc fraction is predicted to pass from TLR4 through cytokines such as IL1B, TNF, and IL6.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.479-487
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• 2018

The purpose of this study is to analyze photochemical activity of nursery seedlings under drought stress, using chlorophyll fluorescence reaction analysis. Young nursery seedlings of tomato (Lycopersicon esculentum Mill.) and cucumber (Cucumis sativa L.), were grown under drought stress for 8 days. Analysis of chlorophyll fluorescence reaction (OJIP) and parameters, were performed to evaluate photochemical fluctuation in nursery seedlings under drought stress. Chlorophyll fluorescence reaction analysis showed maximal recorded fluorescence (P) decreased from the 5 day after treatment in tomato seedlings, while an amount of chlorophyll fluorescence increased at the J-I step. Thus, physiological activity was reduced. In cucumber seedlings, maximal recorded fluorescence (P) and maximal variable fluorescence ($F_V$) lowered from the 4 day after treatment, and chlorophyll fluorescence intensity of J-I step increased. Chlorophyll fluorescence parameter analysis showed electron transfer efficiency of PSII and PSI were significantly inhibited with decreasing $ET2_O/RC$ and $RE1_O/RC$ from the 5 day after treatment, in tomato seedlings and from the 4 day after treatment, in cucumber seedlings. $ET2_O/RC$ and $PI_{ABS}$ significantly changed. In conclusion, 6 indices such as $F_V/F_M$, $DI_O/RC$, $ET2_O/RC$, $RE1_O/RC$, $PI_{ABS}$ and $PI_{TOTAL}ABS$ were selected for determining drought stress in nursery seedlings. Drought stress factor index (DFI) was used to evaluate whether the crop was healthy or not, under drought stress. Cucumber seedlings were less resistant to drought stress than tomato seedlings, in the process of drought stress.

• The Korean Journal of Archival Studies
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• no.54
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• pp.179-210
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• 2017

By redefining the concept of history, my colleagues and I have reformed our department in terms of curriculum and faculty members. This paper is a report of some of the conclusions that we have obtained from this procedure. Despite a long relationship, two disciplines do not seem to match or complement each other in the Korean education system. We believe that this is due to the fact that the Department of Korean History has focused on "national history (NH)." By conferring a privilege on NH, persons, families, societies, regions, and others were removed from NH. To make matters worse, a biased view that history is just an interpretation has prevailed, and the empiricism of history was weakened, which brought about an indifference in keeping records and archives. In East Asia, "history" means both modern history and archives. The concern about the authenticity of records did not come from H. Jenkinson or L. Duranti, and not even from the electronic environment or the Public Records Act of 1998. Key concepts such as records, documents-archives, manuscripts, authenticity, compilation-appraisal, arrangement, and description are different from their signifiant but are same or similar to their $signifi{\acute{e}}$. In case of "provenance" and "original order," they are used in education and practice in the traditional archives. History includes the recording, archiving, and the story or historiography of an event. In this context, the Department of Korean History should contain a more archives-oriented curriculum and select an archival-trained faculty. On the other hand, the department has accumulated long-term experience with appraisal and description of records; thus, archival science should absorb the criticism of the material. History will be shaken without the help of archives, while archives will lose their root without history. We are at the point in which we need to be reminded why we want to be a historian or an archivist, and for this, the more colleagues, the better.

• Journal of The Korean Association For Science Education
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• v.40 no.6
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• pp.595-609
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• 2020

The purpose of this study is to analyze the experiences of teachers who participated in the development of online science class videos in the context of covid-19, their perception of online science class, and the characteristics of the online science class content developed by teachers. A survey and interviews were conducted with ten elementary school teachers who made online science class videos themselves. Also the characteristics of the online science class were investigated by analyzing the online science class video produced by the participants. As a result, participants in the study recognized the lack of production time, difficulty in filming and editing, concerns over misconceptions, the problem of solving copyrights for existing materials, and the burden of external disclosure. Although it was a teacher who had experience producing online science class video contents, no research participants actively answered the merits of online science class. On the other hand, the study participants cited that the shortcomings of online science classes were that students had fewer opportunities for inquiry and lack of communication or interaction. In particular, these shortcomings were thought to have a great influence on the quality of online science classes, especially in making inquiry classes difficult. Some teachers took a negative view that online science classes could not completely replace face-to-face classes. However, if multiple teachers are presented with supplementary teaching activities that complement the content-based online teaching method, the method of combining online science classes and face-to-face classes is not. Through the analysis of the contents of the online science class, the introduction and arrangement steps of the online science class were similar to the process of the face-to-face science class, but the inquiry step and the conceptual explanation step showed a big difference from the face-to-face science class.