• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.669-669
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• 2013

Hierarchical N doped TiO2 nanostructured catalyst with micro, meso and macro porosity have been synthesized by a facile self-formation route using ammonia and titanium isopropoxide precursor. The samples were calcined in different calcination temperature ranging from $300^{\circ}C$ to $800^{\circ}C$ at slow heating rate ($5^{\circ}C$/min) and designated as NHPT-300 to NHPT-800. $TiO_2$ nanostructured catalyst have been characterized by physico-chemical and spectroscopy methods to explore the structural, electronic and optical properties. UV-Vis diffuse reflectance spectra confirmed the red shift and band gap narrowing due to the doping of N species in TiO2 nanoporous catalyst. Hierarchical macro porosity with fibrous channel patterning was observed (confirmed from FESEM) and well preserved even after calcination at $800^{\circ}C$, indicating the thermal stability. BET results showed that micro and mesoporosity was lost after $500^{\circ}C$ calcination. The photocatalytic activity has been evaluated for methanol oxidation to formaldehyde in visible light. The enhanced photocatalytic activity is attributed to combined synergetic effect of N doping for visible light absorption, micro and mesoporosity for increase of effective surface area and light harvestation, and hierarchical macroporous fibrous structure for multiple reflection and effective charge transfer.

• 한국추진공학회지
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• 제22권2호
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• pp.59-65
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• 2018

AP(Ammonium Perchlorate, $NH_4ClO_4$)를 포함하는 복합화약조성의 등온가열시험시, 일정 순도 이하의 AP를 사용하는 경우 "bulged"현상으로 인해 등온가열시험 결과를 얻을 수 없었다. 본 연구는 품질 혹은 순도에 따른 AP의 열적 안정성 차이에 대해 규명하기 위해 LOT 별 AP에 대해 DSC 결과를 분석하고, 그 분석결과를 등온가열시험 결과 및 ARC결과와 비교분석하였다. 또한 순도가 낮은 AP에 대해서는 재결정을 통해 포함된 불순물을 제거한 후 분석한 결과, 열적 안정성이 높아졌음을 확인하였다. DSC 고압팬을 사용하여 AP 순도를 결정하는 정량적 분석방법을 확립하였다.

• 한국식품영양과학회지
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• 제36권3호
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• pp.269-275
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• 2007

불가사리 추출물을 이용하여 생쥐 비장에 있는 면역세포 활성화 효과에 대해 실험한 결과, 다음과 같은 결과를 얻었다. 첫째, 별불가사리 추출물 중에서 B세포와 대식세포를 활성화시키는 성분은 아세톤처리로 추출할 수 있었다. 둘째, 이 성분은 농도 의존적으로 생쥐 비장세포의 증식반응을 유도하였으며, IL-6와 $IFN-{\gamma}$의 생산을 유도하였다. 셋째, 이 성분은 B세포의 증식을 유도하였으며, 이 때 면역글로불린 IgM과 IgG의 생산도 유도하였다. 넷째, 이 성분은 대식세포주의 일산화질소 생산을 유도하였으며, 또 $TNF-{\alpha}$, GM- CSF와 IL-6의 분비를 유도하였다. 이상의 실험 결과, 본 실험에서 사용한 별불가사리 추출물에는 B세포와 대식세포 같은 면역세포의 증식과 각종 사이토카인을 생산을 유도하여, 면역반응을 조절하는 성분이 포함되어 있는 것으로 생각된다.

• 생명과학회지
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• 제22권8호
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• pp.1107-1113
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• 2012

동양에서 한약 재료로 사용되는 칡(Pueraria thunbergiana)은 항산화, 항균효과 및 골다공증 치료 등의 다양한 효과가 있는 것으로 밝혀지고 있지만, 생태학적으로는 산림생태계를 파괴하는 종으로 알려져 있다. 본 연구는 칡의 면역학적 효과를 검증하여 유용한 자원으로 활용하는데 목적이 있다. 칡 추출물을 이용하여 생쥐 비장에 있는 면역세포 활성화 작용을 실험한 결과, 칡 추출물은 첫째, 농도 의존적으로 생쥐 비장세포의 증식 유도하였으며 IL-6, TNF-${\alpha}$, IL-2, IFN-${\gamma}$의 cytokine 생산을 증가시켰다. 둘째, 특히 비장세포 중 칡 추출물은 B세포를 자극하여 세포증식 및 IgM의 생산을 증가시켰다. 셋째, 대식세포주의 일산화질소 생산을 유도하였으며, 또 TNF-${\alpha}$, IL-6 및 IL-$1{\beta}$의 cytokine 분비를 유도하였다. 이상의 실험 결과, 본 실험에서 사용한 칡 추출물은 B세포와 대식세포 같은 면역세포의 증식과 각종 사이토카인을 생산을 유도하기 때문에, 면역반응을 조절하는 성분이 포함되어 있는 것으로 생각되며 특히, 아세톤 추출물이 물 추출물에 비하여 효과적이었다. 따라서 추가적인 실험을 통해, 면역반응을 조절하는 성분을 분리 정제하여 그 특성을 명확히 규명한다면, 각종 의약품이나 건강식품을 개발할 수 있는 원재료로서 칡을 이용할 수 있으며, 부수적으로 산림생태계에 복원에도 기여할 수 있을 것으로 사료된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.