• Title/Summary/Keyword: Cho O

Search Result 5,106, Processing Time 0.05 seconds

Ketyl radical formation of excited 1, 8-naphthalimides in protic polar solvent

  • Cho, Dae Won;Cho, Dae Won;Park, Hea Jung;Yoon, Ung Chan;Lee, Myoung Hee;Im, Chan
    • Rapid Communication in Photoscience
    • /
    • v.1 no.2
    • /
    • pp.35-37
    • /
    • 2012
  • Photoinduced electron-transfer process of 1,8-naphthalimide-linker-trimethylsilane (NI-O3-TMS, O3 = 3,6,9-trioxaundecyl) and NI-O3 has been investigated using the transient absorption measurements in $CH_3CN$ and $CH_3CN/H_2O$. The excitation of NI-O3-TMS in $CH_3CN$ produced the NI radical anion ($NI^{{\cdot}-}$) with a transient absorption band around 413 nm, via the intermolecular electron-transfer between NI moieties in the excited singlet state. In contrast, in a protic polar solvent mixture of $CH_3CN/H_2O$, a proton abstraction process occurred from $NI^{{\cdot}-}$ to generate the NI ketyl radical ($NIH^{\cdot}$), which showed a transient absorption band around 405 nm. The decay time constants of $NIH^{\cdot}$ were quite long compared to those of $NI^{{\cdot}-}$ in $CH_3CN$.

A study on ZnO varistor Design Prevented from Thermal Explosion (열폭주 방지 ZnO 배리스터 설계에 대한 연구)

  • Jung, Tae-Hun;Shin, Hee-Sang;Cho, Sung-Min;Choi, Sung-Wook;Kim, Jae-Chul
    • Proceedings of the KIEE Conference
    • /
    • 2009.07a
    • /
    • pp.1453_1454
    • /
    • 2009
  • This paper examines the characteristics of ZnO varistor to prevent from thermal explosion. We carry out performance evaluation of electrical characteristics on ZnO varistor. we will develop ZnO varistor Prevented from thermal explosion using test result of this paper.

  • PDF

Evaluation of the MgO Protective Layer Deposited by Oxygen Ion-Beam-Assisted-Deposition Method in ac PDPs

  • Li, Zhao-Hui;Cho, Eou-Sik;Hong, Seong-Jae;Kwon, Sang-Jik
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2007.08b
    • /
    • pp.1372-1375
    • /
    • 2007
  • MgO thin films were deposited by $O^+$ IBAD method and results showed assisting oxygen ion beam energy plays a significant role in characteristics of MgO thin films. The lowest firing inception voltage, the highest brightness and the highest luminous efficiency were obtained when oxygen ion beam energy was 300 eV.

  • PDF

Memory Characteristics of MOS Capacitors Embedded with Ge Nanocrystals in $HfO_2$ Layers by Ion Implantation

  • Lee, Hye-Ryoung;Choi, Sam-Jong;Cho, Kyoung-Ah;Kim, Sang-Sig
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2006.11a
    • /
    • pp.147-148
    • /
    • 2006
  • Ge nanocrystals(NCs)-embedded MOS capacitors are charactenzed in this work using capacitance-voltage measurement. High-k dielectrics $HfO_2$ are employed for the gate material m the MOS capacitors, and the C-V curves obtained from $O_2-$ and $NH_3$-annealed $HfO_2$ films are analyzed.

  • PDF

Anti-Ulcer Effect of $Apigenin-7-O-{\beta}-D-Glucuronide$ Isolated from Chrysanthemum morifolium Ramataelle (단국화로부터 분리한 $Apigenin-7-O-{\beta}-D-Glucuronide$의 항궤양 효과)

  • Yoon, Won-Ho;Cho, Choa-Hyung;Lee, Keyong-Ho
    • Korean Journal of Pharmacognosy
    • /
    • v.36 no.3 s.142
    • /
    • pp.171-176
    • /
    • 2005
  • A known flavonoid compound, $apigenin-7-O-{\beta}-D-glucuronide$, was isolated from the flowers of Chrysanthemum morifolium. Isolated compound, $apigenin-7-O-{\beta}-D-glucuronide$ showed strong anti-ulceric activity in rats.

Modified sorbitol MacConkey agar for the rapid isolation of Escherichia coli O157:H7

  • Jung, Byeong-yeal;Jung, Suk-chan;Lee, Na-kyung;Cho, Seong-kun;Cho, Dong-hee;Her, Moon;Yoon, Yong-dhuk;Kim, Bong-hwan
    • Korean Journal of Veterinary Research
    • /
    • v.39 no.4
    • /
    • pp.765-771
    • /
    • 1999
  • Unlike most Escherichia coli strains, E coli O157 : H7 didn't ferment sorbitol within 24h of incubation and showed a negative reaction for $\beta$-glucuronidase. We developed a new medium for the rapid isolation of E coli O157 : H7 using sorbitol MacConkey agar with cefixime, potassium tellurite and 4-methylumbelliferyl-${\beta}$-D-glucuronide (MUG) as a primary plating medium. The addition of $20{\mu}g/ml$ of vancomycin in enrichment broth for E coli O157 : H7 inhibited lots of Gram positive bacteria. Three strains (10.3%) of 29 non-O157 E coli strains and 3 strains (8.3%) of 36 Salmonella spp were inhibited at the $0.05{\mu}g/ml$ of cefixime and 23 strains (79.3%) of 29 non-O157 E coli strains and 12 strains (33.3%) of 36 Salmonella spp were inhibited at the $2.0{\mu}g/ml$ of potassium tellurite. But none of the E coli O157 : H7 was affected at these concentration. The addition of MUG at $100{\mu}g/ml$ level to sorbitol MacConkey agar with cefixime and potassium tellurite (CTM-SMAC) aided in the rapid isolation of E coli O157 : H7 from samples by checking sorbitol-negative and $\beta$-glucuronidase negative phenotypes simultaneously. In conclusion, inoculation of a positive in the O157 screening test from enrichment broth on CTM-SMAC appeared to be a rapid, cost-effective and sensitive method for the isolation of E coli O157 : H7.

  • PDF

The effect of initial Pd catalyst oxidation stale on CH$_4$sensitivity of SnO$_2$thin film sensor (Pd 촉매의 부분 산화 조절을 이용한 SnO$_2$박막 센서의 CH$_4$감도 변화 연구)

  • Choi, W. K.;Cho, J.;Cho, J. S.;Song, J. H.;Jung, H. J.;Koh, S. K.
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.6 no.2
    • /
    • pp.45-49
    • /
    • 1999
  • A flammable gas sensor based on the $SnO_2$thin film deposited by the reactive ion assisted deposition was fabricated and ultra-thin Pd layer as catalyst was adsorbed at surface by ion beam sputtering. The initial oxidation states of Pd catalyst were controlled to investigate the role of Pd in the sensing process of inflammale gas sensor through annealing in air and vacuum respectively. The Pd catalyst existing in pure metallic state showed the sensitivity higher than that of PdO. The result might be closely related to the fact that PdO as a surface acceptor would receive electrons via Pd sub-channel from $SnO_2$, and thus which reduces the sensitivity and delay the response time.

  • PDF

The Application of TiO2 Hollow Spheres on Dye-sensitized Solar Cells

  • Cho, H. J.;Jung, D.
    • Bulletin of the Korean Chemical Society
    • /
    • v.32 no.12
    • /
    • pp.4382-4386
    • /
    • 2011
  • $TiO_2$ hollow spheres were fabricated by using $SiO_2$ as an inorganic template. Spherical $SiO_2$ particles were coated by $TiO_2$ through the nucleation process, and then the core $SiO_2$ part was eliminated by using HF solution. Finally, $TiO_2$ hollow spheres were obtained. The size of the $TiO_2$ hollow spheres was about 300-400 nm and the thickness of the hollow wall was about 20-30 nm. The hollow has several holes whose diameters were within 100-200 nm. Dye-sensitized solar cells fabricated by using the $TiO_2$ hollow spheres were characterized. The solar conversion efficiency of the cell was 8.45% when $TiO_2$ hollow spheres were used as a scattering material, while it was 4.59% when $TiO_2$ hollow spheres were used as a normal electrode material.

[ LiCoO2 ] Thin Film Deposited by Bias Sputtering Method I. Electrochemical Characteristics (바이어스 스퍼터링 법으로 제조된 LiCoO2박막 I. 전기화학적 특성)

  • Lee, Y.J.;Park, H.Y.;Cho, W.I.;Cho, B.W.;Kim, K.B.
    • Journal of the Korean Electrochemical Society
    • /
    • v.6 no.4
    • /
    • pp.261-265
    • /
    • 2003
  • The heat treatment process of thin film microbatteries manufacturing processes has several Problems. This study, without heat treatment, considered the characteristics of $LiCoO_2$ thin films deposited by bais sputtering method inducing the structural change of the thin film. The properties of deposited $LiCoO_2$ thin films such as crystal structure, morphology, and discharge capacity were observed by various analysis methods. Among $LiCoO_2$ thin films deposited by substrate bias $voltage(V_b)$, the one deposited by substrate bias voltage of -50V had the highest initial discharge capacity of about $60{\mu}Ah/cm^2{\mu}m.$ We confirmed that $LiCoO_2$ thin film could be used as cathode material of lithium thin film microbatteries without annealing.