• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.86-86
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• 2004

• 한국항공우주학회지
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• 제34권11호
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• pp.84-91
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• 2006

최근에 인공위성용 전자소자는 우주방사선에 좀 더 강한 소자를 요구되어진다. 왜냐하면, 인공위성의 수명과 기능은 우주방사선으로부터 영향을 받기 때문이다. 또한, 과거에는 부품단위의 우주방사선 시험을 수행하지 않고 유닛 또는 서브시스템 단위의 우주방사선 시험을 수행하였다. 게다가, 발사된 인공위성이 작동오류 상태에 있을 때 그 이유를 분석하기에는 그다지 쉬운 일은 아니다. 따라서, 발사 전 부품 단위 우주방사선 시험을 수행하여 주요 소자에 대한 우주방사선에 의한 영향을 분석 할 필요가 있으며, 지상에서 데이터를 확보할 필요가 있다. 그러므로, 본 논문에서는 모든 전자소자의 기본이라 할 수 있는 금속-산화막 반도체 전계효과 트랜지스터의 총이온화선량에 대한 영향 시험을 수행하기 위한 테스트 베드를 제안한다.

• 천문학논총
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• 제30권2호
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• pp.549-552
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• 2015

The galactic magnetic field (GMF) and the intergalactic magnetic field (IGMF) affect the propagation of ultra-high energy cosmic rays (UHECRs) from the source to us. Here we examine the influences of the GMF/IGFM and the dependence of their sky distribution on galactic latitude, b. We analyze the correlation between the arrival direction (AD) of UHECRs observed by the Pierre Auger Observatory and the large-scale structure of the universe in regions of sky divided by b. Specifically, we compare the AD distribution of observed UHECRs to that of mock UHECRs generated from a source model constructed with active galactic nuclei. Our source model has the smearing angle as a free parameter that reflects the deflection angle of UHECRs from the source. The results show that larger smearing angles are required for the observed distribution of UHECRs in lower galactic latitude regions. We obtain, for instance, a $1{\sigma}$ credible interval for smearing angle of $0^{\circ}{\leq}{\theta}_s{\leq}72^{\circ}$ at high galactic latitudes, $60^{\circ}$ < $\left|{b}\right|{\leq}90^{\circ}$, and of $75^{\circ}{\leq}{\theta}_s{\leq}180^{\circ}$, $-30^{\circ}{\leq}b{\leq}30^{\circ}$, at low galactic latitudes, respectively. The results show that the influence of the GMF is stronger than that of the IGMF. In addition, we can estimate the strength of GMFs by these values; if we assume that UHECRs would have heavier nuclei, the estimated strengths of GMF are consistent with the observational value of a few ${\mu}G$. More data from the future experiments may make UHECR astronomy possible.

• Journal of Astronomy and Space Sciences
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• 제33권4호
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• pp.319-321
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• 2016

Reviewing the two MeV-GeV investigations in the field of the HESS J1745-303 performed using Fermi Large Area Telescope data, we confirmed that the emission peak comfortably coincides with 'Region A' in the TeV regime, which is the brightest part of this feature. The MeV-TeV spectrum can be precisely described by a single power-law. Also, recent investigation has shown that the MeV-GeV feature is elongated from 'Region A' toward the north-west, which is similar to the case of largescale atomic/molecular gas distribution.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1052-1060
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• 2023

The airborne radiation monitoring has been used in geophysics for more than forty years and now it also has its important role in emergency monitoring. The aircraft background and the cosmic gamma-rays contribute to the measured gamma spectrum on the aircraft board. This adverse effect should be eliminated before the data processing. The paper describes two semiparametric methods to estimate the full spectrum aircraft background and cosmic gamma-ray contribution from spectra measured at altitudes where terrestrial contribution is negligible. The methods only assume to know possible peak positions in spectra and their full width at half maximum, that can be easily obtained e.g. from terrestrial measurement. The methods were applied to real experimental data acquired on Mi-17 and Bell 412 helicopter boards. The IRIS airborne gamma-ray spectrometer, with 4×4 L NaI(Tl) crystals, produced by Pico Envirotec Inc., Canada, was used on helicopters' boards. To obtain valid estimate of the aircraft background and the cosmic contribution, the measurements over sea and large water areas were carried out. However, the satisfactory results over inland were also achieved comparing with those acquired over large water areas.

• 천문학회지
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• 제37권5호
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• pp.601-603
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• 2004

We present the results of the linear analysis for the Parker-Jeans instability in the magnetized gas disks including the effect of cosmic-ray diffusion along the magnetic field lines. We adopted an uni-formly rotating two temperature layered disk with a horizontal magnetic fields and solved the perturbed equations numerically. Fragmentation of gases takes place and filamentary structures are formed by the growth of the instability. Nagai et al. (1998) showed that the direction of filaments being formed by the Parker-Jeans instability depends on the strength of pressure outside the unperturbed gas disk. We found that at some range of external pressures the direction of filaments is also governed by the value of the diffusion coefficient of CR along the magnetic field lines k.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권1호
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• pp.100-100
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• 2004

Silicon Charge Detector is to measure the charge of incident cosmic-ray nuclei with a resolution of 0.2 charge unit for atomic number, Z=1-30 with energy range from 1 to 1000 TeV. It is one of detectors for CREAM (Cosmic Ray Energetics And Mass) experiment to test current models of source and acceleration mechanisms of ultra high energy cosmic rays. It's first flight will be with a NASA zero pressure balloon planned to be launched from McMurdo Station, Antarctica in December 2004. (omitted)

• 천문학회지
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• 제29권spc1호
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• pp.271-272
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• 1996

Assuming that particles can be accelerated to high energies via diffusive shock acceleration process at the accretion shocks formed by the infalling flow toward the clusters of galaxies, we have calculated the expected spectrum of high-energy protons from the cosmological ensemble of the cluster accretion shocks. The model with Jokipii diffusion limit could explain the observed cosmic ray spectrum near $10^{19}eV$ with reasonable parameters and models if about $10^{-4}$ of the infalling kinetic energy can be injected into the intergalactic space as the high energy particles.

• 천문학회보
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• 제41권1호
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• pp.72.4-73
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• 2016

For the development of magneto rotational instability, which drives mass accretion in protoplanetary disks, sufficient ionization degree is needed. Cosmic rays are believed to be one of the dominant ionization sources for protoplanetary disk gas. In previous studies, ionization rates are computed by considering the effect of attenuation of the cosmic ray (CR) intensity as a function of column density in an unmagnetized cloud. However, in reality particles should sweep up larger column density to reach at the midplane of disk due to their gyromotion. In this study, we investigate the propagation of CR protons in a protoplanetary disk by solving transport and energy loss equations. We discuss the change in CR intensity due to magnetic field in a protoplanetary disk.

• 천문학회보
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• 제37권2호
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• pp.72.2-72.2
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• 2012

We analyzed the properties of shock waves in galaxy clusters, by using the data of simulations for the large-scale structure of the universe with the spatial resolution of up to 25 kpc/h. In a substantial fraction of clusters, we found that strong shocks with Mach number of several or larger exist in outskirts within the virial radius. They are produced by the accretion of warm gas flowing from filaments to clusters, and generate large cosmic-ray fluxes. The cosmic rays advect into cluster cores, but may temporally induce the population inversion, that is, larger population at larger radius, suggested by recent radio and ${\gamma}$-ray observations.