• Title/Summary/Keyword: Chemical characteristics

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Synthesis and Optical Characteristics of Green Emitting $(Y,Gd)Al_3(BO_3)_4$:Tb Phosphor for PDP application

  • Han, B.Y.;Shin, H.H.;Yoo, J.S.;Kim, C.K.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08b
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    • pp.1352-1355
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    • 2007
  • An new green phosphor, $(Y,Gd)Al_3(BO_3)_4$:Tb was synthesized by flux assisted solid reaction and its VUV excitation and emission characteristics were examined. The luminance of $(Y,Gd)Al_3(BO_3)_4$:Tb at 147 nm excitation was higher than that of $YBO_3:Tb$, while keeping the spectra and decay time of Tb ion same as those of $YBO_3:Tb$.

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Pervaporation Separation of Water/Ethanol Mixtures through PBMA/anionic PAA IPN Membrane

  • Jin, Young-Sub;Kim, Sung-Chul
    • Proceedings of the Membrane Society of Korea Conference
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    • 1996.10a
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    • pp.86-87
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    • 1996
  • IPN (Interpenetrating Polymer Network) is a mixture of two or more crosslinked polymers with physically interlocked network structures between the component polymers. IPN can be classified as an alloy of thermosets and has the characteristics of thermosets such as the thermal resistance and chemical resistance and also has the characteristics of polymer alloys with enhanced impact resistance and amphoteric properties. The physical interlocking during the synthesis restricts the phase separation of the component polymer with chemical pinning process, thus the control of morphology is possible through variations of the reaction temperature and pressure, catalyst concentration and crosslinking agent concentration. Finely dispersed domain structure can be obtained through IPN synthesis of polymer components with gross immiscibility. In membrane applications, particularly for the separation of liquid mixtures, crosslinked polymer component with specific affinity to the permeate is needed. With the presence of the permeant-inert polymer component, the mechanical strength and the selectivity of the membranes are enhanced by restricting the swelling of the transporting polymer component networks.

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Characteristics and Fabrication of Vertical Type Organic Light Emitting Transistors

  • Oh, Se-Young;Kim, Hee-Jeong;Lee, Ji-Young;Ryu, Seung-Hoon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1440-1442
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    • 2005
  • We have fabricated vertical type organic thin film transistors (OTFTs) using organic semiconductor materials such as F16CuPc, NTCDA, PTCDI C-8 and C60. The layers of OTFT were fabricated by vacuum evaporation technique and spin casting method onto the Indium Tin Oxide (ITO) coated glass. I-V characteristics and on-off ratios of the fabricated OTFTs were investigated. In addition, we have fabricated light emitting transistor using MEH-PPV and then investigated EL electroluminescent properties.

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Hydrophobic Modification of Fiber Surface by Plasma Polymerizafon of Perfluoropropene (Perfluoropropene의 플리즈마중합에 의한 섬유의 소수성 표면개질)

  • Seo, Eun-Deock;Kang, Young-Reep;Lim, Hak-Sang
    • Textile Coloration and Finishing
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    • v.3 no.4
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    • pp.22-28
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    • 1991
  • Perfluoropropene was plasma polymerized in the form of thin film on PET fabrics to give hydrophobic and barrier properties without affecting air permeability. Changes in surface characteristics were detected by application of ESCA, IR, SEM and contact anglemeter. The surface properties was changed markedly to be water and stain repellent although the effect was not much sensitive to the differences of chemical components of the thin films formed at different experimental conditions. The protective barrier characteristics of the thin film was also applicable to suppress the amounts of dyes extracted from fabrics in laundering.

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Physico-chemical characteristics of mangrove soil in Gulf of Kachchh, Gujarat, India

  • Rajal, Patel;Lamb, Christian;Roshan, Bhagat;Kamboj, R.D.;Harshad, Salvi
    • Advances in environmental research
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    • v.8 no.1
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    • pp.39-54
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    • 2019
  • This paper presents comprehensive scientific details about mangrove soil in Gulf of Kachchh, Gujarat. A total of ten sites were studied during November, 2011 to December, 2014 in order to know the physico-chemical characteristics of mangrove soil. The results indicated that the soil in GoK had silty loam texture. Other physico-chemical parameters ranged as; pH: 7.39-7.61, Bulk Density: 0.30 g/㎤-0.54 g/㎤, Particle Density: 1.26 g/㎤-1.76 g/㎤, Organic Carbon: 0.70%-1.13%, Organic Matter: 1.01%-1.74% and Moisture Content: 33.45%-56.38%. The paper would be useful to the stakeholders, coastal managers and scientific communities to know the mangrove soil conditions of Gulf of Kachchh for management and planning for conservation of mangrove ecosystem.

Synthesis of spherical phosphors (Y,Gd)$BO_3$:Eu from Precursors in Polymeric Form by Aerosol Pyrolysis

  • Jeoung, Byung-Woo;Yoo, Won-Tae;Hong, Gun-Young;Yoo, Jae-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.788-791
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    • 2002
  • The phosphors of high luminous efficiency for PDP application must have high purity, single phase, and dense surface. In this work, the polymeric reaction was applied to preparation of spherical phosphor by aerosol pyrolysis in order to enhance mechanical and optical characteristics. The red phosphor of (Y,Gd)$BO_3$:Eu was prepared from polymeric precursor, in which citric acid and ethylene glycol were used as ion carriers, i.e monomers. For enhancing the luminescence intensity and mechanical characteristics. optimum synthesizing condition were investigated through concentration of monomers, synthetic temperature. doped activator concentrations, and annealing process. The phosphors synthesized with monomers showed quite different morphology from those without monomers. It was observed that polymeric precursor made an effect on particle formation mechanism and status of particles surface. The resultant spherical phosphors show the comparable luminescent properties to the commercial product (product by Nichia co.). Also, they were observed to have the rigid surface.

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Studies on the Characteristics of the Catalyst Layer of the PEMFC Electrode (고분자전해질용 연료전지의 전극 촉매중 특성에 관한 연구)

  • Sridhar, Parthasarathi;Ihm, Jae-Wook;Yu, Hyung-Kyun;Ryu, Ho-Jin
    • Journal of the Korean Electrochemical Society
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    • v.6 no.1
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    • pp.65-67
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    • 2003
  • The present paper highlights on the need to understand the correlation of the characteristics of the catalyst layer with the performance of the polymer electrolyte membrane fuel cell (PEMFC). This paper deals with the correlation of the platinum loading in the catalyst layer and the performance of the polymer electrolyte membrane fuel cell and also the correlation of the required hydrophilicity/hydrophobicity in the catalyst layer to get the optimum performance under given operating conditions.

Characteristics of Electroantennogram Parameters for the Detection of Odorants

  • Yun, Eung-Sik;Ko, Hwi-Jin;Sun, Jong-Hwan;Park, Tai-Hyun
    • Journal of Microbiology and Biotechnology
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    • v.10 no.6
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    • pp.885-888
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    • 2000
  • Electroantennogram(EAG) can be applied to detect odorants since insects have highly specialized olfactory receptors inside their antennae. The characteristics of EAG parameters were investigated for the quantitative measurement of a general odorant using ammonia as a model odorant. The antennae of male silkworm moth, Bombyx mori, were used for the EAG. The electical signal curves generated from a pair of antennae originating from the same silkworm moth were never identical; however, they exhibited a typical type I or type II characteristic curve pattern for every pair of antennae. The correlation between the EAG parameters and the ammonia concentration was analyzed for the type I and type II antennae. The stability of each parameter was also investigated for each type of antenna. The results show the possibility of the quantitative measurement of general odorants using the EAG technique.

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Preparation and Electrochemical Characteristics of CNFs/DAAQ Electrode for Energy Storage

  • Kim Hong-Il;Kim Han-Joo;Choi Weon-Kyung;Osaka Testuya;Park Soo-Gil
    • KIEE International Transactions on Electrophysics and Applications
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    • v.5C no.4
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    • pp.171-175
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    • 2005
  • A new type of supercapacitor was constructed by using carbon nanofibers (CNFs) and DAAQ (l,5-diaminoanthraquinone) oligomer. DAAQ was deposited on the carbon nanofibers by chemical polymerization with ammonium peroxodisulfate (($NH_4)_2S_2O_8$) as oxidant in the 0.1 M $H_2SO_4$. Polymerization reaction was carried out with constant sonication. From the analysis, it is clear that surface of carbon nanofibers was quite uniformly coated with DAAQ. The performance characteristics of the supercapacitors have been evaluated using Cyclic Voltammetry. CNFs/DAAQ based composite electrode showed relatively good electrochemical behaviors in acidic electrolyte system. CNFs/DAAQ composite electrode showed relatively good capacitance (7 Ah/kg) compared to conventional capacitors in the range of $-0.4\~0.4$.

Influence of Surface Treatment of Polyimide Film on Adhesion Enhancement between Polyimide and Metal Films

  • Park, Soo-Jin;Lee, Eun-Jung;Kwon, Soo-Han
    • Bulletin of the Korean Chemical Society
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    • v.28 no.2
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    • pp.188-192
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    • 2007
  • In this work, the effects of chemical treatment of polyimide films were studied by FT-IR, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angles. The adhesion characteristics of the films were also investigated in the peel strengths of polyimide/aluminum films. The increases of surface functional groups of KOH-treated polyimide films were greatly correlated with the polar component of surface free energy. The peel strength of polyimides to metal substrate was also greatly enhanced by increasing the KOH treatment time, which can be attributed to the formation of polar functional groups on the polyimide surfaces, resulting in enhancement of the work of adhesion between polymer film and metal plate.