• Title/Summary/Keyword: O/M ratio

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Synthesis and Characteristics of LiCoO2 Powders Prepared by SHS Process (자전연소합성법을 이용한 리튬이차전지용 양극활물질 LiCoO2의 제조 및 특성)

  • ;;;Hayk H. Nersisyan
    • Journal of the Korean Ceramic Society
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    • v.41 no.5
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    • pp.388-394
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    • 2004
  • LiCoO$_2$ as the cathode activity material for lithium secondary battery was prepared from a homogeneously mixed powder of LiNO$_3$/Co by SHS process under argon gas. The characteristics of powder including electrochemical properties were investigated according to various reaction conditions. The reaction temperature/velocity and the size of LiCoO$_2$ were controlled by Li/Co molar ratio and a cooling rate of the specimen, respectively. The maximum discharge capacity was 145 mAh/g on 1.05 Li/Co molar ratio and the relatively stable cycling characteristic with 6.4% of capacity fading was obtained after 10th charging-discharging test.

Effect of Fe2+/Fe3+ Molar Ratio on the Synthesized Magnetic Black Pigment by Hydrothermal Method (수열합성법으로 제조한 흑색 자성안료의 Fe2+/Fe3+ 몰비에 따른 특성)

  • Jung, Myung-Ho;Jang, Gun-Eik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.12
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    • pp.812-816
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    • 2017
  • $Fe_3O_4$ was prepared on the $TiO_2-coated$ natural mica substrate. The natural mica has an average particle size of $22{\mu}m$. The substrate was coated on $TiO_2$ thin films using hydrothermal synthesis at pH 1.5-2.5 at $75^{\circ}C$. The Fe precursor solution was prepared by mixing $FeSO_4$ (for $Fe^{2+}$ ion) and $FeCl_3$ (for $Fe^{3+}$ ions) with different molar ratios such as 1/2, 1/1, 2/1, 3/0, and $Fe_3O_4$ only. X-ray diffraction analysis shows that the crystal structure depends on the $FeCl_3-to-FeSO_4$ molar ratio. $Fe_3O_4$ crystal phase could be obtained at higher $FeSO_4$ contents.

Sputtering of Magnesium Oxide this film for Plasma Display Panel Application (PDP용 MgO 박막의 스퍼터 연구)

  • Choi, Young-Wook;Kim, Jee-Hyun
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1732-1734
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    • 2003
  • An MgO thin film sputtering system for the PDP (Plasma Display Panel) applications has been developed. This system was manufactured with a vertical In-Line type of 42 inch, which has the length of 520 mm and the width of 900 mm. A reactive magnetron discharge for this sputtering was generated using an unipolar pulsed power supply which has functions of constant voltage (Max. 500 V) and current (Max. 15 A) control, frequency of $10{\sim}100$ kHz and duty ratio of $10{\sim}60$ %. The experiment was conducted under various conditions : $3{\sim}10$ mTorr of pressure, the ratio of $O_2$/Ar = $0.1{\sim}0.5$, 50 % of duty and power of $0.5{\sim}1.7$ kW. From the experiment, the deposition rate of a static state and a moving state were measured to be about 45 nm/min and 6 nm m/min at the distance of 50 mm between the target and the substrate, respectively.

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The structural, optical and photocatalytic properties of $TiO_2$ thin films fabricated by do magnetron sputtering (직류 마그네트론 스퍼터링법으로 제조된 $TiO_2$ 박막의 구조적, 광학적 특성 및 광촉매 효과)

  • Lim, J.M.;Yang, H.H.;Kim, Y.J.;Park, J.Y.;Jeong, W.J.;Park, G.C.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.420-423
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    • 2003
  • [ $TiO_2$ ] thin films were fabricated by DC magnetron sputtering system at by controlling deposition times, ratios of $Ar:O_2$ partial presser ratio and substrate conditions. And the surface, cross-section morphology, microstructure, and composition ratio of the films were analyzed by FE-SEM, TEM and XPS. Besides, the optical absorption and transmittance of the $TiO_2$ films were measured by a UV-VIS-NIR Spectrophotometer, and photocatalytic properties were studied by G C Analyzer & Data Analysis system. As the result, when $TiO_2$ thin film was made at deposition time of 120[min] and $Ar:O_2$ ratio of 60:40, the best structural and optical properties among many thin films could be accepted. The best results of properties were as follows: thickness; $360{\sim}370[nm]$, grain size; 40[m], gap between two peak binding energy, $5.8{\pm}0.05[eV]$ ($2p_{3/2}$ peak and $2p_{1/2}$ peak of Ti was show at $458.3{\pm}0.05[eV]$ and $464.1{\pm}0.05[eV]$ respectively), binding energy; $530{\pm}0.05\;[eV]$, opticalenergy band gap; 3.4[eV].

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A rounding algorithm for altemate machine scheduling (대안기계 스케쥴링 문제에 대한 라운딩 알고리듬)

  • Hwang, Hak-Jin
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2006.11a
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    • pp.147-157
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    • 2006
  • In this paper we consider alternate m machine scheduling problem in which each job having at most two eligible machines should be assigned with the objective of makespan minimization. For this problem, we propose a $O(m2^m)$ time rounding algorithm with performance ratio at most 1.5. For a little general problem where each job can be processed at most three machines, we prove that there cannot exist a polynomial time algorithm with performance ratio less than 1.5.

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The Non-Linear Characteristics of ZnO Devices. (ZnO 소자의 비직선 특성)

  • Hong, Kyung-Jin;Chon, Kyung-Nam;Cho, Jae-Cheol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05a
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    • pp.43-46
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    • 2001
  • The ZnO devices using semiconductor properties, to include $MnO_2$, $Y_2O_3$ and other material, was fabricated by $Sb_2O_3$ mol ratio from 1 to 4 [mol%]. The non-linearity factor was calculated by setting current to be $1[mA/cm^2]$ and $10[mA/cm^2]$. The spinel structure was fonned by $Sb_2O_3$ addition and it was depressed the ZnO grain formation. The grain growing was controlled by spinel structure that has improved the non-linearity factors. The breakdown voltage characteristics of semiconductor devices to increase with $Sb_2O_3$ was increased in voltage-current. The non-linearity value of ZnO semiconductor devices was 45 over.

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The effect of dissolved oxygen and initial complextation of Cu(II) and EDTA on photooxidation of Cu(II)-EDTA by TiO2 (TiO2 광측매를 이용한 Cu(II)-EDTA의 산화에서 용존산소와 Cu(II)와 EDTA 초기 당량의 영향)

  • 정흥호;성기웅;조영현;이영석;최상원
    • Journal of Environmental Science International
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    • v.11 no.1
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    • pp.85-91
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    • 2002
  • The effects of initial concentration of dissolved oxygen content, Cu(II) and EDTA in an aqueous Cu(II)-EDTA solution on $TiO_2$ photo-oxidation of EDTA were investigated using $TiO_2$ (Degussa P-25) and UV irradiation at $20{\circ}C$. In the presence of dissolved oxygen and/or Cu(II) the photo-oxidation rates of EDTA were enhanced. The rates linearly increased in the range of initial Cu(II) concentration below 1.79 mM, while abode this concentration those were kept constant. The trend or the EDTA photo-oxidation rates appeared to be akin to the Langmuir-Hinshelwood equation farm and the k values calculated were 0.05 mM/min for the free-EDTA system, and 0.17 mM/min far the Cu(II)-EDTA system. These meant the aqueous EDTA decomposition was enhanced due to weakening of the intra-molecular bond strength of EDTA by complexation with Cu(II) added. It was concluded the decomposition of aqueous EDTA by $TiO_2$ photo-oxidation was maximum in the presence of dissolved oxygen supplied by air purging and of Cu(II) with its concentration for 1:1 Cu(II)-EDTA complexation ratio.

Influences of Glass Texturing on Efficiency of Dye-Sensitized Solar Cells

  • Lee, Yong Min;Nam, Sang-Hun;Boo, Jin-Hyo
    • Applied Science and Convergence Technology
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    • v.24 no.6
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    • pp.289-292
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    • 2015
  • The etching processes of glass in aqueous hydrofluoric acid (HF) solutions were used to improve the current density of solar cell. In this study, the textured glass substrate has been etched by solution and the $TiO_2$ thin films have been prepared on this textured glass. After the $TiO_2$ film deposition the surface has been etched by HF under different concentration and the etched $TiO_2$ thin films had a longer electron lifetime and higher haze ratio as well as light scattering, resulting in 1.7 times increment of dye-sensitized solar-cell(DSSC) efficiency. Increases in the surface root-mean-square roughness of glass substrates from 80 nm to 1774 nm enhanced haze ratio in above 300 nm wavelength. In particular, haze ratio of etched $TiO_2$ films on textured glass showed gradually increasing tendency at 550 nm wavelength by increasing of HF concentration up to 10M, suggesting a formation of crater with various sizes on its surface.

Microstructure and Electrical Properties of Pb[(Mg,Mn)Nb]O3-Pb(Zr,Ti)O3 Piezoelectric Ceramics

  • Kim, Jin-Ho;Kim, Jong-Hwa;Baik, Seung-Woo
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.5
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    • pp.202-209
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    • 2005
  • Phase evolution, microstructure and the electrical properties such as $k_p$ and $Q_m$ of $Pb(Mg_{1/3}Nb_{2/3})O_3[PMN]-Pb(Mn_{1/3}Nb_{2/3})O3[PM'N]-PbZrO_3[PZ]-PbTiO_3[PT]$ quaternary system were investigated within the compositional ranges $0{\leq}y{\leq}0.125$, y+z=0.125, and $0.39{\leq}x{\leq}0.54$ of the formula $Pb_{0.97}Sr_{0.03}[Mg_{1/3}Nb_{2/3})_y\;(Mn_{1/3}Nb_{2/3})_z\;(Zr_{x}Ti_{1-x})_{1-(y+z)}]O_3$. In the case of increasing Mn/(Mg+Mn) ratio for a fixed Zr/Ti ratio of 47.5/52.5, phase relation remained unchanged but the grain size drastically decreased, and the electrical properties changed as following: both $k_P$ and $Q_m$ reached the peak values at $Mn/(Mg+Mn)\cong0.3l7$ and gradually decreased; $\varepsilon33^T$ showed a monotonic decrease; P-E hysteresis loop gradually changed to asymmetrical one, and $E_i$ increased in correspondence. With increasing Zr/Ti ratio for a fixed Mn/(Mg+Mn) ratio of 0.317, on the contrary, the cell parameter $(\alpha^2c)^{1/3}$ gradually increased, and tetragonal-rhombohedral morphotropic phase boundary appeared in the range of $51/49{\leq}Zr/Ti{\leq}54/46$. the meantime, the grain size substantially increased, and the electrical properties changed as following: $k_P$ and $\varepsilon33^T$ reached peak values at Zr/Ti=51/49 and 48/52, respectively, and then gradually decreased; change of $Q_m$ was adverse to $k_P$; both $E_C\;and\;E_i$ considerably decreased while $P_S$ moderately increased. For the system 0.125(PMN+PM'N)-0.875PZT studied, the composition Mn/(Mg+Mn)=0.3l7 and Zr/Ti=51/49 revealed some promising electrical properties for piezoelectric transformer application such as $k_P=0.58,\;Q_m\cong1000$, and $\varepsilon^T_{33}=970$, as well as dense and fine-grained microstructure.

Development of a Hydrogen Peroxide Sensor Based on Palladium and Copper Electroplated Laser Induced Graphene Electrode (PdCu를 전기 도금한 레이저 유도 그래핀 전극 기반의 과산화수소 측정 센서 개발)

  • Park, Daehan;Han, Ji-Hoon;Kim, Taeheon;Pak, Jungho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.12
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    • pp.1626-1632
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    • 2018
  • In this paper, we describe the fabrication and characterization of a hydrogen peroxide ($H_2O_2$) sensor based on palladium and copper (PdCu) electroplated laser induced graphene (LIG) electrodes. $CO_2$ laser was used to form LIG electrodes on a PI film. This fabrication method allows simple control of the LIG electrode size and shape. The PdCu was electrochemically deposited on the LIG electrodes to improve the electrocatalytic reaction with $H_2O_2$. The electrochemical performance of this sensor was evaluated in terms of selectivity, sensitivity, and linearity. The physical characterization of this sensor was conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which confirmed that PdCu was formed on the laser induced graphene electrode. In order to increase the sensor sensitivity, the Pd:Cu ratio of the electroplated PdCu was varied to five different values and the condition of highest amperometric current at an identical of $H_2O_2$ concentration was chosen among them. The resulting amperometric current was highest when the ratio of Pd:Cu was 7:3 and this Pd;Cu ratio was employed in the sensor fabrication. The fabricated PdCu/LIG electrode based $H_2O_2$ sensor exhibited a sensitivity of $139.4{\mu}A/mM{\cdot}cm^2$, a broad linear range between 0 mM and 16 mM of $H_2O_2$ concentrations at applied potential of -0.15 V, and high reproducibility (RSD = 2.6%). The selectivity of the fabricated sensors was also evaluated by applying ascorbic acid, glucose, and lactose separately onto the sensor in order to see if the sensor ourput is affected by one of them and the sensor output was not affected. In conclusion, the proposed PdCu/LIG electrode based $H_2O_2$ sensor seems to be suitable $H_2O_2$ sensor in various applications.