• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.910-914
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• 2010

A novel synthetic route has been developed to prepare $\alpha$-cobalt hydroxide with intercalated nitrate anions. It was successfully synthesized by $\gamma$-ray irradiation under simple conditions, i.e., air atmosphere, without base. Under $\gamma$-ray irradiation, it leads to the formation of layered cobalt hydroxynitrate compounds which have small crystalline size and have the role of a generator of hydroxyl anion. Structural and morphological characterizations were performed by using power X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). The component and thermal stability of the sample were respectively measured by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, and thermal analyses, including thermogravimetry (TG) and differential thermal analysis (DTA).

• Nuclear Engineering and Technology
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• v.7 no.2
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• pp.85-94
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• 1975

The n-type germanium crystals have been irradiated by $^{60}$ Co gamma-ray with 647 Mrad at room temperature for compensation. The Ge(${\gamma}$) detectors were fabricated from the gamma-ray irradiated germanium single crystals. The detector characteristics of the Ge (${\gamma}$) detectors were comparable to those of thin Ge(Li) detectors and high purity germanium detectors. The thermal stability of the Ge (${\gamma}$) detector showed a feasibility for ambient temperature storage.

• Journal of Astronomy and Space Sciences
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• v.29 no.1
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• pp.51-55
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• 2012

A few high-mass X-ray binaries-consisting of an OB star plus compact companion-have been observed by Fermi and ground-based Cerenkov telescopes like High Energy Stereoscopic System (HESS) to be sources of very high energy (VHE; up to 30 TeV) ${\gamma}$-rays. This paper focuses on the prominent ${\gamma}$-ray source, LS 5039, which consists of a massive O6.5V star in a 3.9-day-period, mildly elliptical ($e{\approx}0.24$) orbit with its companion, assumed here to be an unmagnetized compact object (e.g., black hole). Using three dimensional smoothed particle hydrodynamics simulations of the Bondi-Hoyle accretion of the O-star wind onto the companion, we find that the orbital phase variation of the accretion follows very closely the simple Bondi-Hoyle-Lyttleton (BHL) rate for the local radius and wind speed. Moreover, a simple model, wherein intrinsic emission of ${\gamma}$-rays is assumed to track this accretion rate, reproduces quite well Fermi observations of the phase variation of ${\gamma}$-rays in the energy range 0.1-10 GeV. However for the VHE (0.1-30 TeV) radiation observed by the HESS Cerenkov telescope, it is important to account also for photon-photon interactions between the ${\gamma}$-rays and the stellar optical/UV radiation, which effectively attenuates much of the strong emission near periastron. When this is included, we find that this simple BHL accretion model also quite naturally fits the HESS light curve, thus making it a strong alternative to the pulsar-wind-shock models commonly invoked to explain such VHE ${\gamma}$-ray emission in massive-star binaries.

• Journal of Radiation Industry
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• v.7 no.1
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• pp.45-49
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• 2013

In tissue engineering application, a fibrous structure of scaffolds has been issued as an alternative system to regulate cell survival and tissue regeneration, and electrospinning technique has been popularly used to generate fibrous meshes or sheets mimicking the structure of native extracellular matrix (ECM). However, recent strategy in the scaffold development is expanded to provide the structural property as well as a biological property of native ECM, a variety of surface modification techniques have been used to introduce biological property. In this study, we developed biomimetic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nano- and micro-fibrous scaffolds as a unique platform with structural and biological properties with native ECM using electrospinning method and gamma-ray irradiation. Surface morphology of the scaffolds was observed by scanning electron microscopy, and alteration of surface property was evaluated with toluidine blue O staining, water contact angle measurement and ATR-FTIR analysis.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.183-190
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• 2001

The activity concentration of primordial radionuclides i.e., $^{238}U$ series, $^{232}Th$ series and $^{40}K$, in soil samples collected from Udagamandalam environment, have been measured by employing NaI (Tl) Gamma ray Spectrometer. The absorbed gamma dose rate has also been simultaneously measured by using both Environmental Radiation Dosimeter at each soil sampling location (ambient gamma dose) as well as from the gamma dose derived from the activity concentration of the primordial radionuclides. The results of activity concentration of each radio nuclides in soil, absorbed dose rate in air due to soil activity and possible cosmic radiation at each location along with human effective dose equivalent for Udagamandalam environment are presented and discussed.

• Nuclear Engineering and Technology
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• v.42 no.3
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• pp.313-318
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• 2010

Alnine pellets were installed in a nuclear power plant for one or two operation cycles and measured by electron spin resonance (ESR) spectrometers for dosimetry. Dose and "x/y ratio", i.e., satellite peak over main center peak ratio, were measured for the returned alanine dosimeters from the nuclear power plant and compared to the values of reference alanine dosimeters exposed only to gamma rays. The variation of the x/y ratio change depended on the population of radicals from each radiation component with different LET. The gamma dose in a mixed radiation field was estimated by an additive gamma ray irradiation experiment and the measured dose rate at specified locations in the containment building.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3398-3402
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• 2022

We fabricated a 15 m long position-sensitive plastic scintillation optical fiber (PSOF) detector consisting of a PSOF, two photomultiplier tubes, four fast amplifiers, and a digitizer. A single PSOF was used as a sensing part to estimate the gamma-ray source position, and ¹³⁷Cs, an uncollimated solid-disk-type radioactive isotope, was used as a gamma-ray emitter. To improve the sensitivity, accuracy, and measurement time of a PSOF detector compared to those of previous studies, the performance of the amplifier was optimized, and the digital signal processing (DSP) was newly designed in this study. Moreover, we could measure very low dose rates of gamma-rays with high sensitivity and accuracy in a very short time using our proposed PSOF detector. The results of this study indicate that it is possible to accurately and quickly locate the position of a very low dose rate gamma-ray source in a wide range of contaminated areas using the proposed position-sensitive PSOF detector.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.4
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• pp.47-53
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• 1997

We fabricated gamma radiation detector using high resistive p-Cd$_{80}$Zn$_{20}$Te grown by high pressure bridgman method and forming au thin film electrode by chemically electroless deposition method. The device of Au/Cd$_{80}$Zn$_{20}$Te/Au is a typical MIM structure. The characteristic of current-voltage showed good linearity to 3kV/cm but it depend on the square of electric field over 3kV/cm. As the results of rutherford backscattering spectroscope(RBS) and auger spectroscope on the Au/Cd$_{80}$Zn$_{20}$Te, Au penetrated to the surface of Cd$_{80}$Zn$_{20}$Te detector absorbed slightly high energy radiation like a few hundred keV and showed good performance to detect low energy gamma ray.mma ray.

• Environmental Analysis Health and Toxicology
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• v.16 no.1
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• pp.17-20
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• 2001

The alkaline comet assay, employing a single-cell gel electrophoresis(SCGE), is a rapid, simple and sensitive technique for visualizing and measuring DNA damage leading to strand breakage in individual mammalian cells. The protecting effect of pretreatment with vitamin C and cysteine on the DNA damage of gamma ray was investigated in mice splenic lymphocytes. Vitamin C and cysteine were administered orally for five consecutive days before irradiation. Four week old ICR male mice were irradiated wish 3.5Gy of γ-radiation and were sacrificed 3 days later. Spleens were taken for DNA damage examination by Comet assay and the tail moments of DNA single -strand breaks in tole splenic lymphocytes were evaluated. The results show that pretreatment with vitamin C and cysteine were effective in protecting against DNA damage by gamma ray. Administration of antioxidants like vitamin C and cysteine to mice before irradiation was effective in reducing the tail moment of splenic lymphocytes DNA.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.247-252
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• 2010

The present study has been performed to select the osmotic tolerant lines using polyethylene glycol (PEG 6000) through an in vitro and in vivo mutagensis with a gamma-ray. During the screening, we selected three mutant lines that seemed to confer elevated osmotic tolerance in high concentrations of PEG 6000. Fruits of these mutants (Os-HK101, Os-HK102 and Os-HK103) were increased to sugar concentration, L-glutamine acid, vitamin C content and lycopine content than those of the wild type. Also the chlorophyll contents were few decreased more in the three mutant lines than the WT plants. Our results suggest that the Os-HK101 is characterized as osmotic stress tolerance considering the sugar concentration and lycopine content. It is expected that the result of this study can be used for breeding more competitive species with respect to contents in sugar or functional chemicals from the selected osmotic resistant lines.