• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2014.11a
• /
• pp.237-238
• /
• 2014

비정질 투명 전도성 산화물의 전기적 특성을 개선하기 위해 불순물 도입을 통한 연구가 많이 진행되고 있다. 하지만 50 nm의 박막 두께에서는 물론, 얇은 박막 두께에 맞춰 극미량의 Sn 첨가를 통한 4성분계 IZO에 대한 연구는 보고된 바 없다. 본 연구에서는 DC 마그네트론 스퍼터링 법을 이용하여 Sn을 미량 도핑 한 50 nm IZO 박막을 제조하였으며, 후열처리 전후의 전기적, 기계적, 광학성 특성을 비교 분석 하였다. Sn이 미량 도핑 되었을 때 전기적 특성이 개선되었고, 이러한 현상은 후열처리 온도에 따라 뚜렷하게 관찰되었다. 이것은 불순물 Sn이 전기적으로 활성화되었기 때문이라고 생각된다.

• Journal of the Korean Ceramic Society
• /
• v.40 no.1
• /
• pp.11-17
• /
• 2003

The effect of$ZrO_2$addition on the microstructure and electrical properties of Ni-Mn oxide NTC thermistors was studied. Major phases present in the sintered bodies of $Ni_{1.0}Mn_{2-x}Zr_xO_4$ were the solid solutions of Ni-Mn-Zr oxides with a cubic spinel structure and the $ZrO_2$ with a tetragonal structure. The $ZrO_2$ was formed by the partial decomposition or incomplete formation of the Ni-Mn-Zr oxides during sintering. With increasing the amount of added $ZrO_2$, the $ZrO_2$ phase increased. The relationship between log resistivity (log p) and the reciprocal of absolute temperature (1/T) of the NTC thermistors prepared was linear, indicative of NTC characteristics. The resistivity, B constant and activation energy of the thermistors increased with increasing $ZrO_2$ content.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.41 no.1
• /
• pp.9-20
• /
• 2015

Ultraviolet radiation (UV) is a major cause of skin photoaging, and effective UV protecting agents are needed for the skin health and beauty. This study was undertaken to examine the effects of Bambusae caulis in Taeniam extract (BCTE) on UVB-induced cell death, oxidative stress and matrix metalloproteinase 1 (MMP1) expression in cell-based assays. HaCaT human keratinocytes were exposed to UVB in the presence of BCTE at different concentrations and resulting changes in cell viability and biochemical events were determined. The results showed that BCTE enhanced the viabilities of UVB-exposed cells, and attenuated apoptotic events such as cleavage of procaspase 3 to its active form, and the increase of Bax to Bcl-2 ratios. BCTE also attenuated the reactive oxygen generation and lipid peroxidation in cells exposed to UVB. Additionally, it attenuated the expression of matrix metalloproteinase 1 and the phosphorylation of c-Jun N-terminal kinase stimulated by UVB. Conclusively, the present study demonstrated that BCTE pro tected skin cells from the UVB-induced cell death, oxidative stress and MMP1 expression, suggesting its potential use as a cosmetic ingredient mitigating some features of the skin photoaging.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.4
• /
• pp.411-420
• /
• 2018

This study presents a revised crackling core model for the description of $UO_2$ sphere oxidation in air atmosphere. For close reproduction of the sigmoid behavior exhibited in $UO_2$ to $U_3O_8$ conversion, the fragmentation effect contributing to the increased reactive surface area and the concept of variable grain conversion time were considered in the model development. Under the assumptions of two-step successive reaction of $UO_2{\rightarrow}U_3O_7{\rightarrow}U_3O_8$ and final grain conversion time equivalent to ten times the initial grain conversion time, the revised model showed good agreement with the experimental data measured at 599 - 674 K and a lowest deviation when compared with Nucleation and Growth model and AutoCatalytic Reaction model. The evaluated activation energy at 100% conversion to $U_3O_8$, $57.6kJ{\cdot}mol^{-1}$, was found to be closer to the experimentally extrapolated value than to the value determined in AutoCatalytic Reaction model, $48.6kJ{\cdot}mol^{-1}$.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.11a
• /
• pp.203-208
• /
• 2004

We are living now under the bad air pollition contained the many plus(+)ion produed by the exhaust gases from automobil and Industrial plant. To be refreshe those air pollution. We developed the funtional lighting fixture which emit the lighting, negative(-)ion and Infraredray. The negative(-)ion and Infraredray refresh the air pollition and will arise nature healing power lot the human body and activate the body cell, and makes the good blood circulation and then we had the experiment to the Biological effect by the funtional lighting fixture.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.8
• /
• pp.4723-4728
• /
• 2014

In this study, a thermoelectric module (TEM) and a diesel engine were modeled using 1-D commercial software AMESim, and the performance of the TEM was evaluated when the engine was operated under the NEDC driving cycle. The goal of TEM modeling was to investigate not only the waste heat recovery (WHR) rate and energy converting efficiency, but also the heat transfer rate by taking the materials characteristics into account. In addition, a diesel oxidation catalyst (DOC) was designed, and it was found that the waste heat recovery with TEM affects the activation of DOC and alters engine exhaust composition. The simulation indicated that the WHR using TEM is beneficial for decreasing the fuel consumption of vehicles, but the reduction in the exhaust temperature affects the activation of DOC, resulting in an approximately 14% increase in CO and HC emissions. Therefore, the effect of waste heat recovery on the automotive emission characteristics must be considered in the development of automotive engine WHR systems.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.10
• /
• pp.731-738
• /
• 2011

In this study AOPs of $O_3/UV$ radiation, $O_3/Mg(OH)_2/UV$ radiation and $O_3/MgO/UV$ radiation system for phenol treatment in aqueous solution was performed in a laboratory scale circulating batch reacter. Flow rate of ozone 1.0 L/min, ozone concentrations $150{\pm}10mg/L$ was maintained constantly at the above-mentioned oxidation processes. During the oxidation processes the $COD_{Cr}$ and TOC was measured in the composition. The pseudo first-order rate constants of the processes was $5.12{\times}10^{-5}$, $1.19{\times}10^{-4}$ and $1.79{\times}10^{-4}sec^{-1}$, and the activation energy was 3.03, 1.79 and $2.32kcal{\cdot}mol^{-1}$ at $20^{\circ}C$, respectively. It was found that both $Mg(OH)_2$ and MgO had remarkable accelerations on degradation of phenol and removal of COD in water. On this basis, $O_3/MgO/UV$ system is an effective and feasible routes for catalytic ozonation of phenol in water.

• Korean Journal of Microbiology
• /
• v.24 no.2
• /
• pp.133-140
• /
• 1986

Extracts of CO-autotrophically grown cells of Acinetobacter sp. 1 were shown to use thionin, methylene blue, or 2,6-dichlorophenol-indophenol, but not NAD, NADP, FAD, or FMN, as electron acceptors for the oxidation of CO under strictly anaerobic conditions. The CO dehydrogenase (CO-DH) in the thes bacterium was found to be an inducible enzyme. The enzyme activity was determined by an assay based on the CO-dependent reduction of thionin. Maximal reaction rates were found at pH 7.5 and $60^{\circ}C$, and the Arrhenius plot revealed an activation energy of 6.1 kcal/mol(25.5kJ/mol). THe $K_m$ m/ for CO was $154{\mu}M$. Known metalchelating agents tested had no effects on the CO-DH activity. No divalent cations tested affect the enzyme activity significantly escept $Cu^{2+}$ which suppressed the activity completely. The enzyme was inhibited by glucose and succinate. The same extracts catalyzed oxidation of hydrogen gas and formate with thionin as electron acceptor. The CO-DH of Acinetobacter sp. 1 was to have no immunological relationship with that of Pseudomonas carboxydohydrogena.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.236-236
• /
• 2010

알루미늄 자체에 대한 질화 기술의 어려움 때문에 현재까지는 AlN 분말을 이용한 소결 공정을 통하여 주요 부품의 제작이 되어 왔으며. Al 질화 기술보다는 아노다이징과 같은 표면 산화 공정 또는 도금과 같은 기술이 선호되어 왔다. 알루미늄 질화 기술이 잘 사용되지 않았던 이유는 알루미늄 표면에 2 5 nm 두께로 존재하는 치밀한 산화층의 높은 안정성 때문에 질화반응이 어렵기 때문이다. 이 알루미늄 산화물의 안정성은 질화물에 비교하여 5 배까지 높으며, 이런 경향은 온도가 높아짐에 따라 더욱 커지기 때문이다. 특히, 알루미늄의 낮은 기계적 물성을 향상시키기 위해서는 충분히 깊은 두께로 형성되어야 할 필요성이 높으나 알루미늄에 대한 질소의 고용도가 거의 없고 확산 계수가 매우 낮기 때문에 충분히 두꺼운 질화층의 형성이 어렵기 때문이다. 결국, 알루미늄 질화가 가능하기 위해서는 표면의 산화층을 없애야 하며, 알루미늄이 AlN이 되려는 속도는 $Al_2O_3$를 만드려는 속도보다 매우 느리므로, 잔존 산소량을 최소화 할 필요성이 있어서 고진공 분위기에서 처리되어야 한다. 일반적으로 알루미늄 질화를 위해서는 $10^{-6}\;torr$ 이하의 고진공도의 챔버가 필요하며 고순도의 반응 가스를 사용하여야 한다. 그러나 이러한 고진공하에서는 낮은 이온밀도 때문에 신속질화가 기존의 공정시간인 20시간동안, AlN층이 5um이하로 형성되었다. 본 연구에서, 알루미늄의 질화에 있어서, 표면층에 높은 전류를 걸어주어, 용융상태로 만들어주는 것이 좋다는 연구 결과를 얻었으며, 이를 토대로 신속질화를 위하여 전류밀도(전력량)에 따라 알루미늄 질화층의 형성 정도를 연구하였다. SEM, EDS, XRD등을 통해 Al의 표면에 플라즈마 질화를 통해 Al에 질소의 함유량이 증가하는 것을 확인하였으며 광학현미경을 통해 질화층의 두께와 표면조직을 확인하였다. Al 시편의 표면을 효과적으로 활성화할 수 있는 $400^{\circ}C$ 이상의 온도에서 전류밀도(전력량)와 시간의 변화에 따라 질화층이 효과적으로 형성되는 조건과 시간에 따라 두께가 증가하는 경향을 확인할 수 있었다. 이러한 신속 질화 공정을 통해 2시간 이내의 질화를 통해 40um이상의 AlN층을 형성할 수 있었다.

• Journal of Applied Biological Chemistry
• /
• v.65 no.4
• /
• pp.239-245
• /
• 2022

Although normal activation of platelets is important in the process of hemostasis, excessive or abnormal activation of platelets can lead to cardiovascular diseases. Therefore, the discovery of novel substances capable of regulating or inhibiting platelet activation may be helpful in the prevention and treatment of cardiovascular diseases. Artemether is a derivative of artemisinin, known as an active ingredient of Artemisia annua, which has been reported to be effective in treating malaria, and is known to function through antioxidant and metabolic enzyme inhibition. However, the role of artemether in platelet activation and aggregation and the mechanism of action of artemether in collagen-induced human platelets are not known until now. This study investigated the effects of artemether on platelet activation and thrombus formation induced by collagen. As a result, cAMP level was significantly increased by artemether, and VASP and IP3R, substrates of cAMP-dependent kinase, were phosphorylated. IP3R phosphorylation by Artemether inhibited Ca²⁺ recruitment into the cytoplasm, and phosphorylated VASP inhibited fibrinogen binding by inactivating αIIb/β3 located on the platelet membrane. Consequently, artemether inhibited thrombin-induced fibrin clot formation. Therefore, we propose that artemether can act as an effective prophylactic and therapeutic agent for cardiovascular diseases caused by excessive platelet activation and thrombus formation.