• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.263.2-263.2
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• 2003

There is now increasing evidence that free radicals and active oxygen species are involved in a variety of pathological events. Free radical-mediated cell damage and free radical attack on polyunsaturated fatty acids result in the formation of lipid radicals. These lipid radicals react readily with molecular oxygen to produce peroxy radicals responsible for initiating lipid peroxidation. The peroxidation of cellular membrane lipid can lead to cell necrosis and considered to ve implicated in a number of pathophysiological conditions including liver disease. (omitted)

• 청정기술
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• 제20권3호
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• pp.212-217
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• 2014

재생공정에서 황화 된 탈황흡수제의 재생을 위하여 산소는 산화제로 사용되었다. 재생공정에서 미량의 미 반응 산소는 직접 황 회수 공정으로 유입된다. 그러나, $SO_2$ 환원을 위한 반응성은 미 반응 산소의 다양한 이유에 의해서 저하된다. $SO_2$ 환원을 위한 반응성 실험을 위해 Sn-Zr계 촉매가 사용되었으며, $SO_2$와 $O_2$는 각각 5.0 vol%와 4.0 vol%로 고정하였고 $300-450^{\circ}C$와 1-20 atm에서 수행되었다. 본 연구에서는 고온건식 탈황공정의 직접 황 회수공정에 유입되는 미 반응산소에 의한 촉매반응성 저하에 미치는 영향을 조사하였다. $SO_2$ 환원으로 생성된 원소 황은 미 반응산소에 의해서 재산화되고, redox반응기구에서 Sn-Zr계 촉매의 빈 격자 산소자리가 미 반응산소에 의해서 재산화되므로 $SO_2$ 전화율은 감소되는 것으로 판단된다. 한편 환원제로써 공급된 CO는 미 반응산소에 의해서 산화되어 연소열에 의해 촉매 충전 층 온도가 상승되기도 한다. 결과적으로 충전 층의 빠른 온도상승은 활성 물질을 소결시켜 촉매의 비활성화를 초래하게 된다.

• 한국전기전자재료학회논문지
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• 제14권10호
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• pp.861-867
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• 2001

In this paper, in order to investigate the catalytic effect of the sludge exhausted from waterworks on NO$_{x}$ removal, we measure NO removal characteristics with and without sludge pellets in BaTiO$_3$-sludge packed-bed reactor of plate-plate geometry. NO initial concentration is 50 ppm balanced with air and a gas flow rate is 5ι/min. Gas temperature is changed from 25 to 10$0^{\circ}C$ to investigate the role of sludge pellet on removing active oxygen species and NO$_2$. BaTiO$_3$pellets is filled for coronal discharge at upstream of reactor and sludge pellets is filled for catalytic effect at downstream of reactor. The volume percent of sludge pellets to BaTiO$_3$pellets is changed from 0% to 100% and AC voltage is supplied to the reactor for discharging simulated gases. In the results, when sludge pellets is put at the downstream of plasma reactor, NO removal rate is slightly increased. However, NO$_2$and $O_3$ as by-products during NO removal is significantly decreased from 51ppm without sludge pellets to 5 ppm with sludge pellets and from 50 ppm without sludge pellets to 0.004ppm with sludge pellets, respectively. Therefore, NO$_{x}$(NO+NO$_2$) removal rate is increased up to 93%. It is thought that sludge pellet maybe react with active oxygen species and NO$_2$ generated by corona discharge in surface of BaTiO$_3$pellets, the then NO$_2$O$_3$as by-products are considerably decreased. When we increase gas temperature from room temperature to 10$0^{\circ}C$, NO removal rate is decreased, while NO$_2$ concentration is independent on gas temperature. These result suggest that the removal mechanism of active oxygen species and NO$_2$in sludge pellet is not absorption, but chemical reaction. Therefore we expect that sludge pellets exhausted for waterworks could be used as catalyst for NO$_{x}$ removal with high removal rate and low by-product.oduct.

• 한국환경농학회지
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• 제6권2호
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• pp.94-100
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• 1987

미토콘드리아는 가시광선의 조사에 의해 그 고유한 생화학적 기능에 저해를 받게 되며 그것은 주로 파장 영역 $350{\sim}500nm$의 청색광이 유발하는 광역학적 작용(photodynamic action)의 결과라는 가정을 입증하는 자료를 수집하였다. 미토콘드리아막에 결합되어 있는 전자전달계효소들 중에서 NADH dehydrogenase, succinate dehydrogenase, 및 cytochrome c oxidase의 광저해(photoinhibition)를 조사하였던 바, 모든 효소들이 청색광에 의해 상대적으로 심한 활성상실을 보였다. NADH dehydrogenase의 FMN과 cytochrome c oxidase의 heme group은 산소가 관여하는 photosensitizer(photodynamic sensitizer)임에 반해, succinate dehydrogenase의 FAD는 sensitizer로서의 기능을 보이지 않는 대신 Fe-S center가 산소와 무관한 photosensitizer일 것이라고 해석되었다. heme group에 들어 있는 Fe도 역시 산소와 무관한 광화학반응에 어느 정도 기여하리라고 추정되는 결과도 얻었다. 미토콘드리아 전체로 볼 때 생리적 활성저해에 가장 크게 기여하는 가시광은 산소존재 조건하의 청색광이였고, 그 저해기작에는 active oxygens가 관여되어 있다는 것을 $O_2$의 분석을 통해 확인하였다. 한편 active oxygens의 생성은 미토콘드리아막의 과산화를 초래하였으며, 역시 청색광/$O_2$조건에서 그 정도가 가장 심하였다.

• 한국결정성장학회지
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• 제34권3호
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• pp.103-107
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• 2024

본 연구에서는 NCM [Li(Ni_xCo_yMn_z)O₂] 양극활물질을 합성하기 위한 내화갑의 재료로 순수 금속 재료인 Nickel을 제안하였다. Nickel은 산화에 강하고 녹는점이 높은 금속으로 알려져 있다. 니켈은 NCM 양극활물질의 주성분 중 하나로 양극물질 합성 동안에 saggar로 부터의 오염에 대한 문제에 자유로울 것으로 기대하였다. 본 연구진은 니켈이 NCM 양극물질 합성용 내화갑으로서의 가능성을 확인하고자 하였다. 900℃에서 Ni 금속 도가니와 Ni_0.8Co_0.1Mn_0.1(OH)₂ (NCM 811) 전구체 물질을 장시간 반응시켰을 때, 시간 변화에 따른 도가니 표면 반응층 변화를 분석하였다. 900℃에서 열처리 동안에 형성된 니켈 도가니 반응층은 니켈 산화물이었으며, 양극 전구체 산화물로 부터의 산소확산과 대기 중의 산소와 반응이 동시에 이루어져서 생성된 것으로 생각된다. 산화층은 480시간 이후로 그 두께의 변화가 느려지는 것으로 보아 전구체로 부터의 산소 확산속도가 감소되는 것으로 생각된다. 480시간까지는 도가니로 부터 탈락되지 않고 결합되어 있었다. 그러나 720시간 후에는 산화층이 탈락되는 것이 확인되어 일정 시간까지만 NCM 합성용 Saggar로서 사용 가능할 것으로 생각된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.252-253
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• 2011

ZnO-based thin film transistors (TFTs) are of great interest for application in next generation flat panel displays. Most research has been based on amorphous indium-gallium-zinc-oxide (IGZO) TFTs, rather than single binary oxides, such as ZnO, due to the reproducibility, uniformity, and surface smoothness of the IGZO active channel layer. However, recently, intrinsic ZnO-TFTs have been investigated, and TFT- arrayss have been demonstrated as prototypes of flat-panel displays and electronic circuits. However, ZnO thin films have some significant problems for application as an active channel layer of TFTs; it was easy to change the electrical properties of the i-ZnO thin films under external conditions. The variable electrical properties lead to unstable TFTs device characteristics under bias stress and/or temperature. In order to obtain higher performance and more stable ZnO-based TFTs, HZO thin film was used as an active channel layer. It was expected that HZO-TFTs would have more stable electrical characteristics under gate bias stress conditions because the binding energy of Hf-O is greater than that of Zn-O. For deposition of HZO thin films, Hf would be substituted with Zn, and then Hf could be suppressed to generate oxygen vacancies. In this study, the fabrication of the oxide-based TFTs with HZO active channel layer was reported with excellent stability. Application of HZO thin films as an active channel layer improved the TFT device performance and bias stability, as compared to i-ZnO TFTs. The excellent negative bias temperature stress (NBTS) stability of the device was analyzed using the HZO and i-ZnO TFTs transfer curves acquired at a high temperature (473 K).

• 한국포장학회지
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• 제13권1호
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• pp.9-18
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• 2007

Nanocomposite has been considered as an emerging technology in developing a novel food packaging materials. Polymer nanocomposites exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased barrier properties pertaining to gases such as oxygen, carbon dioxide, and water vapor, as well as to UV rays, and increased mechanical properties such as strength, stiffness, dimensional stability, and heat resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. New packaging materials created with this technology demonstrate an increased shelf life with maintaining high quality of the product. Nanotechnology offers big benefits for packaging. Nanocomposite technology paves the way for packaging innovation in the flexible and rigid packaging applications, offering enhanced properties such as greater barrier protection, increased shelf life and lighter-weight materials.

• 한국결정성장학회지
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• 제20권2호
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• pp.80-84
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• 2010

The temperature-programmed reduction of titanium oxide ($TiO_2$) with pure $CH_4$ was used for the preparation of titanium carbide crystallites. The synthesized materials had the different surface areas, indicating that the structural properties of these materials were strong functions of two different heating rates and space velocity employed. The titanium carbide crystallites were active for $NH_3$ decomposition. Since the reactivity varied with changes in the particle size, ammonia decomposition reactivity over the titanium carbides crystallites appeared to be related to the different active species. The reactivities of titanium carbide crystallites were two and three times lower than those of the vanadium and molybdenum carbide crystallites, respectively. These results suggested that the difference in activities might be related to the degree of electron transfer between metals and carbon.

• 신재생에너지
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• 제9권1호
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• pp.51-59
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• 2013

Tantalum carbide crystallites which is to be used for $H_2$ fuel cell has been synthesized via a temperature-programmed reduction of $Ta_2O_5$ with pure $CH_4$. The resultant Ta carbide crystallites prepared using two different heating rates and space velocity exhibit the different surface areas. The $O_2$ uptake has a linear relation with surface area, corresponding to an oxygen capacity of $1.36{\times}10^{13}\;O\;cm^{-2}$. Tantalum carbide crystallites are very active for hydrogen production form ammonia decomposition reaction. Tantalum carbides are as much as two orders of magnitude more active than Pt/C catalyst (Engelhard). The highest activity has been observed at a ratio of $C_1/Ta^{{\delta}+}=0.85$, suggesting the presence of electron transfer between metals and carbon in metal carbides.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.174-174
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• 2012

The nature of feed gas is essential for the active species formed in the nonthermal plasma jets, which would induce various biological phenomena. We investigated the different physiological effects of atmospheric pressure soft-plasma jets on Esherichia coli and blood cells according to the feed gas. Cell death rate, growth curve, membrane molecular changes and induced genes were examined. The relationship between cellular reactions and active species generated by discharge will be discussed.