• Journal of Radiation Protection and Research
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• v.28 no.1
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• pp.19-24
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• 2003

The self-attenuation factor for an $^{198}Au$ sample and the 0.412 MeV gamma-ray penetration ratio in the circular Al-cover of the radiation detector have been determined using an analytical solution and MCNP code. The results show that the self-attenuation factors obtained from the analytical solution coincide with those of MCNP code for all but the Au sample with the relatively larger radius. Then the maximum difference between the two methods appears to be 9 % in the Au sample of 1.5 mm radius. It also is revealed that the analytical solutions of the 0.412 MeV gamma-ray penetration ratio in the Al-cover of 7.62 cm radius are consistent with those of the MCNP code within the standard deviation.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.64-64
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• 1991

The interaction of high-intensity, focused, nanosecond laser light with matter results in the production of high-temperature plasma, which in turn emits an intense pulse of x rays. The x-ray spectrum consists of strong line components of several keV photon energy and broad continuum. Such an x-ray source provides many advantages over conventional ones for many applications. Pulse nature of the x-ray emission is well-suited for studying transient phenomena and for imaging living biological specimen. Recent experiments have also shown that the laser plasma x ray may be used for x ray lithography. These studies and other applications will be discussed in detail.

• Journal of the Korean Chemical Society
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• v.56 no.2
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• pp.217-227
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• 2012

Syntheses of some novel oxomolybdenum(V) and dioxomolybdenum(VI) complexes with an azo dye methoxyphenolazoantipyrine (HL) derived from 4-aminoantipyrine and 2-methoxyphenol are reported. The complexes have been characterized by elemental analyses, molar conductance, magnetic susceptibility data, IR, UV-Vis, $^1H$ NMR, EPR and FAB mass spectral studies. The physicochemical studies and spectral data indicate that HL acts as a bidentate chelating ligand. The complexes have the general formulae [$MoO(HL)XCl_2$] and [$MoO_2(HL)XCl$],where X=Cl, NCS or $NO_3$. All the complexes are found to have distorted octahedral geometry. Structural and morphological characterization of the complexes [$MoO(HL)Cl_3$](1) and [$MoO_2(HL)Cl_2$](4) before and after gamma ray irradiation,was performed by X-ray diffraction and scanning electron microscopy( SEM).The ligand and the complexes were screened for their possible antimicrobial activities.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.30-33
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• 1999

본 연구에서는 Pt/f4-SiC Schottky barrier diodes(SBDs)의 소자 성능향상과 미세구조와의 상관관계를 규명하였다. 다른 열처리 온도구간에 따른 금속/SiC 계면의 미세구조 평가는 X-ray scattering법을 사용하여 분석하였다. 소자의 역 방향 특성은 열처리 온도가 증가함에 따라 저하되었다. As-deposited와 $850^{\circ}C$ 온도에서 열처리된 소자의 최대 항복전압은 각각 1300 V와 626 V 이었다. 그러나, 소자의 순방향 특성은 열처리 온도가 증가함에 따라 향상되었다. X-ray scattering법으로 >$650^{\circ}C$ 이상의 열처리 온도에서는 Pt/SiC 계면에서 Pt-silicides가 형성되었고, 이러한 Silicides의 형성이 Pt/SiC 계면의 평활도를 증가시킨 원인이 됨을 보였다. SBDs의 순방향 특성은 열처리 과정동안 Pt/SiC 계면에서 형성된 silicides의 결정성에 강하게 의존함을 알 수 있었다.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.216-223
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• 2017

In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and $10^{th}$ value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

• Journal of the Korean Magnetics Society
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• v.21 no.6
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• pp.198-203
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• 2011

The electronic structure of ferrimagnetic spinel oxide of $FeV_2O_4$ has been investigated by employing soft x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD). The Fe 2p and V 2p XAS spectra show that the valence states of Fe and V ions are ${\sim}Fe^{2.3+}$ mixed-valent states and ${\sim}V^{3+}$ states, respectively. In Fe 2p XMCD spectra, finite XMCD signals are observed for divalent $Fe^{2+}$ states only, but not for $Fe^{3+}$ states. This finding indicates that the magnetic moments of $Fe^{2+}$ ions are ordered ferromagnetically but that those of $Fe^{3+}$ ions are cancelled, implying that $Fe^{2+}$ ions play an important role in determining magnetic properties of $FeV_2O_4$.

• Journal of radiological science and technology
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• v.42 no.3
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• pp.175-180
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• 2019

In this study, we have researched the effectiveness of silicone pad. A distribution of scatter ray in mammography was evaluated using Monte-Carlo (MC) simulation technique and then a silicone pad was applied to remove the scatter ray for improving image quality. Molybdenum target and Molybdenum filter combination made a difference of 59.8% to a number of photon at 17.5 keV. On the other hand, Tungsten target and Rhodium filter showed a variation of 24.5% at 20 keV. Mean 68 of SNR was increased in Selenia and mean 1.04 of SNR was raised in Senographe. Silicone pad was significantly effective to reduce the scatter ray that was generated by primary X-ray. It can decrease an absorption rate of scatter ray to patient body and whilst it improve the image quality from increasing SNR.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1661-1663
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• 2002

• 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.