• 한국재료학회지
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• 제21권9호
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• pp.520-524
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• 2011

Porous W with controlled pore characteristics was fabricated by a freeze-drying process. $WO_3$ powder and camphene were used as the source materials of W and sublimable vehicles, respectively. Camphene slurries with $WO_3$ contents of 10 and 15 vol% were prepared by milling at $50^{\circ}C$ with a small amount of oligomeric polyester dispersant. Freezing of a slurry was done in a Teflon cylinder attached to a copper bottom plate cooled at $-25^{\circ}C$ while the growth direction of the camphene was unidirectionally controlled. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at $800^{\circ}C$ for 30 min and sintered in a furnace at $900^{\circ}C$ for 1 h under a hydrogen atmosphere. Microstructural observation revealed that all of the sintered samples were composed of only W phase and showed large pores which were aligned parallel to the camphene growth direction. The porosity and pore size increased with increasing camphene content. The difference in the pore characteristics depending on the slurry concentration may be explained by the degree of powder rearrangement in the slurry. The results strongly suggest that a porous metal with the required pore characteristics can be successfully fabricated by a freeze-drying process using metal oxide powders.

• 한국식품영양과학회지
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• 제44권10호
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• pp.1583-1587
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• 2015

본 연구에서는 어린감과 성숙감의 탄닌 함량 및 담즙산과의 결합능력을 비교 조사하였다. 또한 사람의 장내 세포인 Caco-2 cell에 어린감과 성숙감 추출물을 처리한 후 고농도의 DCA로 자극시켜 생성되는 NO의 수준과 TEER의 차이를 확인하였다. 탄닌 함량과 담즙산의 결합능력은 성숙감에 비해 어린감에서 유의적으로 높은 것으로 나타났으며 어린감 산성 에탄올 추출물에서 유의적으로 가장 높은 탄닌 함량 및 담즙산 결합능력을 보였다. NO 생성 억제능으로 확인한 염증반응에서도 어린감 산성 에탄올 추출물이 유의적으로 가장 높은 효과를 보였으며 DCA에 의해 유도된 장세포 간극의 느슨함을 유의하게 막아줄 수 있음이 확인되었다. 본 연구 결과를 토대로 어린감의 산성 에탄올 추출물은 고지방 식사를 통해 고농도로 축적되는 담즙산에 의해 형성된 유해한 장내 환경을 건강하게 유지시켜줄 수 있는 기능성 소재로 개발할 가능성이 있음이 확인되었다.

• 한국응용과학기술학회지
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• 제22권4호
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• pp.315-322
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• 2005

We investigated the electrochemical properties for Langmuir-Blodgett (LB) films mixed with 4-octyl-4'-(5-carboxylpentamethyleneoxy)azobenzene (denoted as 8A5H) and $phospholipid(L-{\alpha}-dimyristoylphosphatidylcholine$, denoted as DMPC). LB films of 8A5H monolayer and 8A5H-DMPC were deposited by using the Langmuir-Blodgett method on the indium tin oxide(ITO) glass. The electrochemical properties measured by using cyclic voltammetry with a three_electrode system, an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode at various concentrations(0.1, 0.5, and 1.0mol/L) of $NaClO_4$ solution. A measuring range was reduced from initial potential to -1350mV, continuously oxidized to 1650mV and measured to the initial point. The scan rates were 50, 100, 150 and 200mV/s, respectively. As a result, LB films of 8A5H monolayer appeared irreversible process caused by only the oxidation current from the cyclic voltammogram and LB films of 8A5H-DMPC mixture were found to be caused by a reversible oxidation-reduction process.

• 센서학회지
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• 제24권1호
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• pp.41-46
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• 2015

In this work, pure hierarchical ZnO structure was prepared using a simple hydrothermal method, and Ag nanoparticles doped hierarchical ZnO structure was synthesized uniformly through photochemical route. The reduced graphene oxide (rGO) has been synthesized by typical Hummer's method and reduced by hydrazine. Prepared Ag/ZnO nanostructures are uniformly dispersed on the surface of rGO sheets using ultrasonication process. The synthesized samples were characterized by SEM, TEM, EDS, XRD and PL spectra. The average size of prepared ZnO microspheres was around $2{\sim}3{\mu}m$ and showed highly uniform. The average size of doped-Ag nanoparticles was 50 nm and decorated into ZnO/rGO network. The $C_2H_2$ gas sensing properties of as-prepared products were investigated using resistivity-type gas sensor. Ag/ZnO-rGO based sensors exhibited good performances for $C_2H_2$ gas in comparison with the Ag/ZnO. The $C_2H_2$ sensor based on Ag/ZnO-rGO had linear response property from 3~1000 ppm of $C_2H_2$ concentration at working temperature of $200^{\circ}C$. The response values with 100 ppm $C_2H_2$ at $200^{\circ}C$ were 22% and 78% for Ag/ZnO and Ag/ZnO-rGO, respectively. In additions, the sensor still shows high sensitivity and quick response/recovery to $C_2H_2$ under high relative humidity conditions. Moreover, the device shows excellent selectivity towards to $C_2H_2$ gas at optimal working temperature of $200^{\circ}C$.

• 대한한방내과학회지
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• 제24권1호
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• pp.113-122
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• 2003

Objective : The aim of this study was to evaluate the efficacy of Gagamchunggan-tang on anti-inflammation reaction with lipopolysaccharide (LPS)-induced HepG2 cell. Method : We examined the effects of the Gagamchunggan-tang, a traditional drug for liver inflammation, on the process of lipopolysaccharide(LPS)-induced nuclear factor-${\kappa}Bp65(NF-{\kappa}Bp65)$ activation in HepG2 cell. SDS-PAGE, Western blotting, Immunofluorescence staining were studied. Results : Immunoblot analysis showed that the level of nucleic $NF-{\kappa}Bp65$ was rapidly up-regulated and cytosolic inhibitory $I-{\kappa}B{\alpha}$ was down-regulated by LPS challenge. While Gagamchunggan-tang inhibited an increase of $NF-{\kappa}Bp65$ and degradation of $I-{\kappa}B{\alpha}$ in HepG2 cell. Besides LPS-induced expression of a group of genes, such as tumor necrosis factor-${\alpha}(TNF-{\alpha})$, inducible nitric oxide synthase(iNOS) and cyclooxygenase-2 (COX-2), are repressed by Gagamchunggan-tang. It may be concluded that Gagamchunggan-tang attenuates the progress of LPS-induced inflammation by reduction of $NF-{\kappa}Bp65$ activation. Conclusion : The Gagamchunggan-tang would be useful as a therapeutic agent for endotoxin-induced liver disease.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.285-285
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• 2010

Zinc oxide (ZnO) is a direct band gap semiconductor with 3.37 eV, which has in a hexagonal wurtzite structure. ZnO is a good candidate for a photocatalyst because it has physical and chemical stability, high oxidative properties, and absorbs of ultraviolet light. During ZnO is irradiated by UV light, redox (reduction and oxidation) reactions will occur on the ZnO surface, generating the radicals O2- and OH. These two powerful oxidizing agents have been proven to be effective in decomposition of harmful organic materials, converting them into CO2 and H2O. Therefore, we assume that oxygen on the surface of ZnO is a very important factor in the photocatalytic activities of ZnO nanoparticles. Recently, ZnO nanoparticles are studied in various application fields by many researchers. Photocatalyst research is progressing much in various application fields. But the ZnO nanoparticles have disadvantage that is unstable in water in comparison titanium dioxide (TiO2). The Zn(OH)2 was formed at the ZnO surface and ZnO become inactive as a photocatalyst when ZnO is present in the solution. Therefore, we prepared synthesized ZnO nanoaprticles that were immersed in the water and dried in the oven. After that, we measured photocatalytic activities of prepared samples and find the cause of their phtocatalytic activity changes. The characterization of ZnO nanoparticles were analyzed by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and BET test. Also we defined the photocatalytic activity of ZnO nanoparticles using UV-VIS Spectroscopy. And we explained changing of photocatalytic activity after the water treatment using X-ray Photoelectron Spectroscopy (XPS).

• Natural Product Sciences
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• 제22권3호
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• pp.193-200
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• 2016

This study describes the anti-inflammatory, anti-oxidant, and melanogenesis inhibition activities of methanol extract and various organic solvent fractions of Arecae Pericarpium. We examined the inhibition of lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells, 1,1-diphenyl-2-picrylhydrazine (DPPH) scavenging activity, mushroom tyrosinase inhibition activity and melanin contents. The study showed that, among all tested fractions, methylene chloride fraction showed the strongest inhibition of LPS-induced NO production in RAW 264.7 cells ($IC_{50}$ value $8.89{\mu}g/mL$) and DPPH radical scavenging activity ($EC_{50}$ value $21.39{\mu}g/mL$). Methylene chloride and ethyl acetate fractions similarly inhibited mushroom tyrosinase activity. Methanol extract exhibited strongest reduction of melanin content in B16F10 melanoma cells. Based on the bioactivity assay results, methylene chloride and ethyl acetate fractions were further separated. Eight phenolic compounds were isolated, which are dimeric syringol (1), catechol (2), 4-hydroxybenzaldehyde (3), vanillin (4), 4-hydroxyacetophenone (5), apocynin (6), protocatechuic acid (7) and 4-hydroxybenzoic acid (8). Among the isolated compounds tested, catechol showed the strongest inhibition of LPS-induced NO production in RAW 264.7 cells. Catechol also showed the concentration-dependent NF-${\kappa}B$ inhibition activity. Arecae Pericarpium might have potentials to be developed as anti-inflammatory agent or dermatological product for skin-whitening agent.

• 생약학회지
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• 제46권4호
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• pp.334-341
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• 2015

HAE series (HAE 01 - 06), are the mixtures of medicinal plants; Lonicerae Folium et Caulis (Lonicera japonica), Scutellariae Radix (Scutellaria baicalensis), Adenophorae Radix (Adenophora triphylla var. japonica), Polygonati Oddorati Rhizoma (Polygonatum odoratum var. pluriflorum), Platycodi Radix (Platycodon grandiflorum), Liriopis seu Ophiopogonis Tuber (Liriope platyphylla). HAE 06 showed the significant antitussive effect in HAE series. HAE 04, 05, and 06 increased the effect of expectorant measured by secretion of phenol red in rats. All tested HAE series were observed to have the anti-oxidant activity determined by the scavenging activity. HAE 01, 03 and 06 were significantly reduced the production of nitric oxide (NO) and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) increased by LPS. HAE 06 was selected based on the results and done further experiments. HAE 06 inhibited the number of coughing induced by citric acid in dose dependent manner. HAE 06 effectively increased the effect of expectorant. HAE 06 exhibited anti-inflammatory effects by inhibiting the production of NO and TNF-${\alpha}$. In addition, HAE 06 significantly suppressed inducible Cyclooxygenase-2 (COX-2). Especially HAE 06 has the highest effect in alleviating the respiratory symptoms. Moreover, the enhancement antioxidant activity and reduction inflammation partly were attributed to it. HAE 06 may become the promising candidate for the treatment of respiratory symptom in the future.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.490-490
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• 2011

Graphene, hexagonal network of carbon atoms forming a one-atom thick planar sheet, has been emerged as a fascinating material for future nanoelectronics. Huge attention has been captured by its extraordinary electronic properties, such as bipolar conductance, half integer quantum Hall effect at room temperature, ballistic transport over ${\sim}0.4{\mu}m$ length and extremely high carrier mobility at room temperature. Several approaches have been developed to produce graphene, such as micromechanical cleavage of highly ordered pyrolytic graphite using adhesive tape, chemical reduction of exfoliated graphite oxide, epitaxial growth of graphene on SiC and single crystalline metal substrate, and chemical vapor deposition (CVD) synthesis. In particular, direct synthesis of graphene using metal catalytic substrate in CVD process provides a new way to large-scale production of graphene film for realization of graphene-based electronics. In this method, metal catalytic substrates including Ni and Cu have been used for CVD synthesis of graphene. There are two proposed mechanism of graphene synthesis: carbon diffusion and precipitation for graphene synthesized on Ni, and surface adsorption for graphene synthesized on Cu, namely, self-limiting growth mechanism, which can be divided by difference of carbon solubility of the metals. Here we present that large area, uniform, and layer controllable graphene synthesized on Cu catalytic substrate is achieved by acetylene-assisted CVD. The number of graphene layer can be simply controlled by adjusting acetylene injection time, verified by Raman spectroscopy. Structural features and full details of mechanism for the growth of layer controllable graphene on Cu were systematically explored by transmission electron microscopy, atomic force microscopy, and secondary ion mass spectroscopy.

• 한국진공학회지
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• 제7권1호
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• pp.11-16
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• 1998

본 연구에서는 GaAs의 selenium보호막형성 효과를 관찰하기 위하여 $Na_2$Se/NH$_4$OH 용액을 제조하고 X-선 광전자 분광기(X-ray photoelectron spectroscopy)와 photoluminescence(PL)를 이용하여 표면처리된 GaAs의 처리직후 및 대기중 노출에 따른 화학적 결합특성 및 광학적 특성을 관찰하였다. 용액처리 직후, 표면에는 As-Se결합이 형성 되었으며 Se는 한가지 산화상태인 -2가로 존재함이 관찰되었다. 또한 세정처리후의 표면보 다 Se용액처리 이후에 PL의 피이크 세기가 크게 증가됨으로부터 Se 용액처리가 GaAs의 표면상태밀도를 효과적으로 감소시킬 수 있음을 확인할 수 있었다. 그러나 처리 직후 공기 중 노출없이 관찰한 GaAs표면에서 산화막이 국부적으로 관찰되었으며 이렇게 처리과정중 생성된 산화막은 대기중 노출에 따라 산화막 성장을 유도하고 표면처리 효과를 저하시키는 주요인으로 작용함을 알 수 있었다. 이는 Se용액처리된 GaAs표면의 PL강도가 대기중 노출 에 따라 감소하며 세정처리후 GaAs표면의 PL강도와 유사한 값을 나타냄으로 부터도 확인 할 수 있었다.