• Journal of Life Science
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• v.22 no.9
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• pp.1137-1144
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• 2012

Inflammation is a host defense mechanism that is activated in response to harmful substances or pathogens. However, an excessive inflammatory response is a problem in itself. Macrophages secrete inflammatory mediators such as nitric oxide (NO) or cytokines through various pathways such as the nuclear factor kappa B (NF-${\kappa}B$)-activated pathway after recognizing pathogen-like lipopolysaccharides (LPSs). In this study, anti-inflammatory effects of Eupatorium chinensis var. simplicifolium (EUC) extracts were investigated using LPS-stimulated RAW 264.7 macrophages. The EUC root extract significantly reduced NO production, inducible nitric oxide synthase (iNOS) expression, and cyclooxygenase-2 expression in a concentration-dependent manner. In addition, the EUC root extract reduced phosphorylation of mitogen-activated protein kinases and protein kinase B, which is upstream of NF-${\kappa}B$. The EUC root extract also reduced the degradation of inhibitory kappa B. These results indicate that EUC root extract exerts anti-inflammatory effects, which are mediated by inhibition of iNOS expression and the NF-${\kappa}B$ pathway.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.296-302
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• 2006

The kinetics of the thermal-oxidative decomposition of waste polyurethane (PU) according to oxygen concentration has been studied using a non-isothermal thermogravimetric technique at several heating rates from 10 to $50^{\circ}C/min$. A kinetic model accounting for the effects of the oxygen concentration by the differential and integral method based on Arrhenius equation was proposed to describe the thermal-oxidative decomposition of waste PU. To obtain the information on the kinetic parameters such as activation energy, reaction order, and pre-exponential factor, the thermogravimetric analysis curves and its derivatives have been analyzed using the kinetic analysis method proposed in this work. From this work, it was found that reaction orders for oxygen concentration had a negative sign, and activation energy decreased as the oxygen concentration increased. It was also found that the kinetic parameters obtained from the integral method using the single heating rate experiments varied with heating rates. Therefore, it is thought that the differential method using the multiple heating rate experiments more effectively represents the thermal-oxidative decomposition of waste polyurethane.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.13-18
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• 2024

To develop flexible electrode materials for wearable devices, we investigated the electrochemical characteristics of carbon fibers tow according to pretreatment. And an electrochemical non-enzymatic sensor was fabricated using glucose as a target. The carbon fibers tow was pretreated through desizing and activation processes, and activation was performed in two ways: chemical oxidation and electrochemical oxidation. Surface morphology of carbon fibers tow samples was observed by SEM and their electrochemical characteristics and sensing performance were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. Carbon fibers tow samples showed improved electrochemical properties such as reduced R_et, ΔE_p, and increased I_p through pretreatment. And similar electrochemical properties were obtained with both activation methods. We selected electrochemically activated carbon fibers tow as the final electrode material for application of electrochemical sensor. The non-enzymatic glucose sensor based on this electrode has an enhanced sensitivity of 0.744 A/mM (in a linear range of 0.09899~3.75423 mM) and 0.330 mA/mM (3.75423~50 mM), respectively. Through this study, the possibility of using carbon fibers tow was confirmed as an electrode material. It is expected to be used as basic research for development of high-performance flexible electrode materials.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.112-117
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• 2004

Volatile organic compounds (VOCs) are low calorific value gases (LCVG) emitted from chemical processes such as painting booth, dye works and drying processes etc. Characteristics of VOCs are low calorific values less than 150kcal/㎥, high activation energy for ignition and low energy output. These characteristics usually make combustion unstable and its treatment processes needs high-energy consumption. The cyclone combustion system is suitable for LCVG burning because it can recirculate energy through a high swirling flow to supply the activation energy for ignition, increases energy density In make a combustion temperature higher than usual swirl combustor and also increases mixing intensity. This research was conducted to develop optimized cyclone combustion system for thermal oxidation of VOCs. This research was executed to establish the effect of swirl number with respect to the combustion temperature and composition of exhausted gas in the specific combustor design.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.522-526
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• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

• The Korean Journal of Food And Nutrition
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• v.14 no.3
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• pp.193-198
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• 2001

고정화 inulinase를 이용하여 inulin으로부터 fruc-tose 시럽을 연속적으로 생산하기 위하여 Bacillus sphaericus 188-1이 생성하는 inulinase를 부분 정제한후 5시간 NaIO$_4$로 산화시킨 cellulose에 고정화시킨 다음 이들의 성질을 조사하였다. 산화 cellulose에 고정화시킨 inulinase의 활성은 g당 47 Unit 이었고 고정화수율과 활성수율은 각각 41%와 39%이었다. 고정화시킨 inulinase의 작용 최적온도와 pH는 각각 5$0^{\circ}C$, pH 9.0이었고 5$0^{\circ}C$, pH 8.0~10.0에서 비교적 안정 하였다 고정화시킨 inulinas의 활성은 K+, Ca2+, Mn2+과 Hg2+에 의하여 활성화 되었으며 EDTA(10mM)에 의하여 심하게 저해되었다.

• Journal of Ginseng Research
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• v.33 no.1
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• pp.1-7
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• 2009

Clinical and animal studies have shown that free radical overload is an important cause for a variety of diseases. Although ginseng has been recognized as antioxidant, how it modulates anti-oxidative process at the molecular level remains unknown. Free radical production is induced by tumor necrosis factor-$\alpha$ (TNF-$\alpha$) under the stress condition, and (TNF-$\alpha$) release is activated by TNF-$\alpha$-converting enzyme (TACE). Since TACE inhibitor is also well known for anti-inflammatory agent, ginseng seems to show anti-oxidative activity by repressing TACE pathway. Further studies on signal transduction would be warranted to elucidate molecular action mechanisms of ginseng on anti-oxidation and anti-inflammation.

• Journal of the Korean Chemical Society
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• v.18 no.2
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• pp.117-125
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• 1974

The catalytic reaction between carbon monoxide and oxygen was investigated in the presence of catalysts which were specially treated by applying an annealing method at different monoxide and oxygen and at reaction temperatures in the region of partial pressures of carbon $40^{\circ}C$ to $95^{\circ}C$. The oxidation rate is highest on NiO annealed at low temperature in vacuum. The data has been correlated with the first order kinetics, and the activation energies from the Arrhenius equation are found to be 4Kcal/mole in the region of the experimental temperatures. The excess oxygen in NiO obtained from the decomposition of $NiCO_3$does not cause activation at $95^{\circ}C$. But NiO catalysts annealed again in vacuum display activation even at $40^{\circ}C$. The quantity of the excess oxygen in NiO surfaces seems to be the controlling factor in determining the rates of oxidation of carbon monoxide.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.294-300
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• 2013

In this study, major parameter of partial nitritation was investigated for the stable operation. In order to establish partial nitritation system, prevailing parameters such as temperature, BA (bicarbonate alkalinity) and pH were evaluated. As a result, it is inferred that appropriate bicarbonate alkalinity ratio (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) drives stable 50% partial nitritation at $32^{\circ}C$ and ambient temperature, respectively. Alkalinity ratio was proposed as new strategy for 50% partial nitritation without pH control in both temperature regimes. Because of the results, it was added amound of BA required only for 50% nitritation to inhibit nitratation. The effluent $NO_2{^-}-N/NH_4{^+}-N$ ratio reached almost 100% when initial bicarbonate alkalinity ratios (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) were 6.8 (R1) and 6.7 (R2), respectively. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) results demonstrated that AOB was the dominant nitrifying bacteria and NOB was negligible after adopting process control.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.206.2-206.2
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• 2015

최근 비정질 산화물 반도체 thin film transistor(TFT)는 차세대 투명 디스플레이로 많은 관심을 받고 있으며 활발한 연구가 진행되고 있다. 산화물 반도체 TFT는 기존의 비정질 실리콘 반도체에 비하여 큰 on/off 전류비, 높은 이동도 그리고 낮은 구동전압으로 인하여 차세대 투명 디스플레이 산업에 적용 가능하다는 장점이 있다. 한편 기존의 sputter나 evaporator를 이용한 증착 방식은 우수한 막의 특성에도 불구하고 많은 시간과 제작비용이 든다는 단점을 가지고 있다. 따라서 본 연구에서는 별도의 고진공 시스템이 필요하지 않을 뿐만 아니라 대면적화에도 유리한 용액공정 방식을 이용하여 박막 트렌지스터를 제작하였으며 thermal 열처리와 microwave 열처리 방식에 따른 전기적 특성을 비교 및 분석하고 각 열처리 방식의 열처리 온도 및 조건을 최적화 하였다. 제작된 박막 트렌지스터는 p-type bulk silicon 위에 산화막이 100 nm 형성된 기판에 spin coater을 이용하여 Al-Zn-Sn-O 박막을 형성하였다. 연속해서 photolithography 공정과 BOE (30:1) 습식 식각 과정을 이용해 활성화 영역을 형성하여 소자를 제작하였다. 제작 된 소자는 Pseudo-MOS FET구조이며, 프로브 탐침을 증착 된 채널층 표면에 직접 접촉시켜 소스와 드레인 역할을 대체하여 동작시킬 수 있어 전기적 특성평가가 용이하다는 장점을 가지고 있다. 그 결과, microwave를 통해 열처리한 소자는 100oC 이하의 낮은 열처리 온도에도 불구하고 furnace를 이용하여 열처리한 소자와 비교하여 subthreshold swing(SS), Ion/off ratio, field-effectmobility 등이 개선되는 것을 확인하였다. 따라서, microwave 열처리 공정은 향후 저온 공정을 요구하는 MOSFET 제작 시의 훌륭한 대안으로 사용 될 것으로 기대된다.