• Title/Summary/Keyword: ${\gamma}electron$

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Detection of Radiation Degradation of LDPE by ESR Spectroscopy (전자스핀공명을 이용한 저밀도 폴리에틸렌의 방사선 열화 검지)

  • Kim Ki-Yup;Lee Chung;Ryu Boo-Hyung
    • Journal of the Korean Society of Safety
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    • v.20 no.1 s.69
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    • pp.81-86
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    • 2005
  • This study has investigated radiation degradation of low density polyethylene(LDPE). Samples were irradiated up to 800kGy using a $Co^{60}\;\gamma-ray$ at a dose rate of 5kGy/hr in the presence of air atmosphere at room temperature. After irradiation, storing for 2 weeks, free radical measurement of LDPE has established by electron spin resonance(ESR). ESR measurement showed that free radical concentration(FRC) was increased with radiation dose and decreased with the time. The radical types showed alkyl, allyl, and peroxy radical with the irradiation, these changed to peroxy radical with the time.

High Temperature Oxidation Behavior and Surface Defect in Fe-25Mn-1.5Al-0.5C Steel (Fe-25Mn-1.5Al-0.5C강의 고온 산화 거동과 표면 결함)

  • Park, Shin Hwa;Hong, Soon Taik;Kim, Tai Wung;Chung, In-Sang
    • Journal of the Korean Society for Heat Treatment
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    • v.13 no.3
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    • pp.158-162
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    • 2000
  • The high temperature oxidation behavior and the surface defect in Fe-25Mn-1.5A1-0.5C steel was investigated by XRD (X-ray Diffractin) and electron microscopy. The intra- and inter-granular oxides were formed by the selective oxidation of manganese and aluminum, which were identified to MnAl2O4 phase. Aluminum nitride (AlN) was formed in front of these oxides. The ${\gamma}$-matrix was transformed to ${\alpha}$- and ${\varepsilon}$- phases by the selective oxidation of manganese. The surface defect, micro-scab was induced by the difference of the high temperature ductility between the matrix and the inter-granular oxide.

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A Study on the Space Charge Polarity Measurement Teasurement Technology of Cross-Linked Polyethylene for Power Cable (전력케이블용 가교폴리에틸렌의 공간전하 극성측정기술에 관한 연구)

  • 국상훈;서장수;김병인;박중순
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.6 no.6
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    • pp.23-31
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    • 1992
  • Charged particle in the polymers is supposed to affect the electrical conduction and to lead them th dielectrical breakdown finally. So we measured the space charge distribution made by application of high electric field and evaluated the polarity of the charged particle affected on electrical conduction and space charge formed in the insulating materials by using temperature gradient thermally stimulated current measurement method(TG-TSC measurement). As a result, in the cross-linked polyethylene, A-peak was caused from dipole polarization, C-peak was caused from ionic space charge polarization and D-peak was injected trap hole. Also we found it crossible the evaluated the polarity of injected trap carrier and electron(or hole) of carrier trap in the cross-lined polyethylene. We found that ${\gamma}$-ray irradiated low density polyethylene had a relation to the electronic trap and we also could get the value of electric field distribution in the samples of which evaluation was available.

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A study on radiation degradation of LDPE by using ESR (ESR을 이용한 저밀도 폴리에틸렌의 방사선 열화에 관한 연구)

  • Kim, Ki-Yup;Kim, Jin-Ah;Lee, Chung;Kim, Pyeong-Jong;Ryu, Boo-Hyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.473-476
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    • 2004
  • This study has investigated radiation degradation of low density polyethylene(LDPE). Samples were irradiated using a $Co^{60}\;\gamma-ray$ and ray up to 800 kGy at a dose rate of 5 kGy/hr in the presence of air atmosphere at room temperature. After irradiation, free radical measurement of LDPE has established by electron spin resonance(ESR). Then, each sample was stored for 2 weeks. ESR measurement showed that free radical concentration(FRC) was increased with radiation dose and changed from alkyl, allyl radical to peroxy radical with time.

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Economic Scale of Radiation Application in Japan

  • Kume, Tamikazu
    • Journal of Radiation Industry
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    • v.5 no.3
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    • pp.191-196
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    • 2011
  • The economic scale of nuclear application is a good indicator to show how the radiation technology is useful and contribute to improve public welfare and living standard. Recent research in Japan shows that the economic scale of nuclear field was 4,112 B¥ for radiation application(46%) and 4,741 B¥ for nuclear energy (54%) playing a role of "two wheels of one cart" in nuclear field and the total 8,853 B¥ constitutes 1.8% of gross domestic products (GDP). The radiation application consisted of 2,295 B¥ (56%) in industry (semiconductor, sterilization, nondestructive testing, radiation processing of tires, etc.), 1,538 B¥ (37%) in medicine (therapy and diagnosis such as X-ray, nuclear medicine, computed tomography, etc.) and 279 B¥ (7%) in agriculture (mutation breeding, food irradiation, sterile insect technique, etc.). Radiation application by ${\gamma}$-ray, electron beam and ion beam is steadily increasing in Japan.

Polymeric Micelle Formation of Multiblock Copolymer Composed of Poly( $\gamma$-benzyl L-glutamate) and Poly(ethylene oxide)

  • Na, Jae Un;Jeong, Yeong Il;Jo, Jong Su
    • Bulletin of the Korean Chemical Society
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    • v.21 no.4
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    • pp.383-388
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    • 2000
  • Multiblock copolymers consisting of poly( g-benzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) as the hydrophilic part (GEG) were synthesized and characterized. GEG polymeric micelles were prepared by the dialysis technique. Particle size distributions based on intensity,volume, and number-average were 22.6 $\pm$ 11.9 nm, 23.5 $\pm$ 4.6 nm, and 23.7 $\pm$ 37 nm, respectively. It was observed that par-ticle size and size distribution of GEG polymeric micelles changed significantly with the choice of initial sol-vent. Transmission electron micrographs (TEM) showed the polymeric micelles to be spherically shaped, with sizes ranging from 20 nm to 40 nm in diameter. Fluorescence spectroscopy measurements suggested that GEG block copolymers wereassociated in water to form polymeric micelles, and the critical micelle concentrations (CMC) value of the block copolymers was 0.0094 g/L. Further evidenceof micelle formation of GEG block copolymers and limited mobility of the PBLG chain in the core ohe micelle was obtained with 1 H NMR in D2O.

The Effects of Cyclic Heat Treatment Process for Fine Microstructure of TiAl Cast Alloy (주조용 TiAl 합금의 조직 미세화를 위한 반복열처리 공정 조건에 관한 연구)

  • Kong, Man-Sik;Yang, Hyunseok
    • Journal of the Korean Society for Heat Treatment
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    • v.32 no.5
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    • pp.195-200
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    • 2019
  • For expanding the applications and workability of TiAl alloy, elongation is very important property. Fine microstructure is needed for elongation and physical properties of TiAl alloys. In this study, The effects of cyclic heat treatment process for fine microstructure of Ti-46Al-Nb-W-Cr-Si-C alloy, which was made by VAR (vacuum arc remelting) and VIM(vacuum induction melting) centrifugal casting process, was investigated. Cycle heat treatment process was very effective for recrystallization of this TiAl system, which has microstructure size of $50{\sim}100{\mu}m$ through pre-heat treatment, cyclic heat treatment in ${\alpha}+{\gamma}$ phase region and solution heat treatment respectively. Refined grain size was finally confirmed by photos of optical microscope and scanning electron microscope.

Modeling and experimental production yield of 64Cu with natCu and natCu-NPs in Tehran Research Reactor

  • Karimi, Zahra;Sadeghi, Mahdi;Ezati, Arsalan
    • Nuclear Engineering and Technology
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    • v.51 no.1
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    • pp.269-274
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    • 2019
  • $^{64}Cu$ is a favorable radionuclide in nuclear medicine applications because of its unique characteristics such as three types of decay (electron capture, ${\beta}^-$ and ${\beta}^+$) and 12.7 h half-life. Production of $^{64}Cu$ by irradiation $^{nat}Cu$ and $^{nat}CuNPs$ in Tehran Research Reactor was investigated. The characteristics of copper nanoparticles were investigated with SEM, TEM and XRD analysis. The cross section of $^{63}Cu(n,{\gamma})^{64}Cu$ reaction was done with TALYS-1.8 code. The activity value of $^{64}Cu$ was calculated with theoretical approach and MCNPX-2.6 code. The results were compared with related experimental results which showed good adaptations between them.

Change of Lacquer Surface by Radiation (방사선에 의한 옻칠표면의 변화)

  • Yoon, Guk-joung
    • Journal of Radiation Industry
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    • v.12 no.4
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    • pp.333-336
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    • 2018
  • Natural lacquer was cured at room temperature at a relative humidity of 60% at $27^{\circ}C$ to obtain a lacquer film. Photolysis of lacquer was investigated by irradiating 1~75 kGy of gamma ray to this lacquer film. No significant changes were observed in the range of 1~10 kGy radiation. As the radiation doses were increased, the white spots were increased in the scanning electron microscope photographs. The increase of the white dots of the lacquer surface shows that the lacquer is degradation by radiation. As a result of IR spectral analysis of the lacquer surface with increasing irradiation dose, there was no significant change in $3,445cm^{-1}$ hydroxide group, $2,900cm^{-1}$ hydrocarbon group, and $993cm^{-1}$ triene group. However, the $1,745cm^{-1}$ carbonyl group was found to increase, and the $1,715cm^{-1}$ unsaturated hydrocarbon group and the $1,463cm^{-1}$ methylene group showed a tendency to decrease.

Relationship between inductively coupled plasma and crystal structure, mechanical and electrical properties of MoN coatings (유도결합 플라즈마 파워에 따른 MoN 코팅막의 결정구조 및 기계·전기적 특성 변화)

  • Jang, Hoon;Chun, Sung-Yong
    • Journal of Surface Science and Engineering
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    • v.55 no.2
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    • pp.77-83
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    • 2022
  • Nanocrystalline MoN coatings were prepared by inductively coupled plasma magnetron sputtering (ICPMS) changing the plasma power from 0 W to 200 W. The properties of the coatings were analyzed by x-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, nanoindentation tester and semiconductor characterization system. As the ICP power increases, the crystal structure of the MoN coatings changed from a mixed phase of γ-Mo2N and α-Mo to a single phase γ-Mo2N. MoN coatings deposited by ICPMS at 200 W showed the most compact microstructure with the highest nanoindentation hardness of 27.1 GPa. The electrical resistivity of the coatings decreased from 691.6 μΩ cm to 325.9 μΩ cm as the ICP power increased.