• Journal of Astronomy and Space Sciences
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• 제18권2호
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• pp.163-173
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• 2001

본 논문에서는 아리랑 2호가 운용될 궤도의 우주방사능 환경 및 single event 영향(SEE)에 관하여 분석하였다. 위성체 외부 및 내부 방사능 환경으로서 지구 자기장 내부에 포획되어 활동하는 포획된 양자, 태양 및 태양계 외부에서 전달되는 SEP(solar energetic particle) 및 GCR(galactic cosmic ray)고 에너지 입자에 대하여 양자와 중이 온으로 구분하여 그들의 스펙트럼을 분석하였다. 아리랑 2호 전자소자로 사용 예정인 Intel 계열 80386 마이크로 프로세서 CPU에 대한 SEU 및 SEL발생률을 추정하였다. 분석결과, 정상적인 조건에서 포획된 양자나 고 에너지 양자에 의한 SEU 영향은 아리랑 2호 위성이 운용되는 3년동안 발생하지 않을 것으로 추정된다. 반면에, GCR 중이온에 의한 SEU 발생은 운용 중에 수차례 발생할 수 있는 것으로 추정되었다. 아리랑 2호는 탑재 소프트웨어의 프로세서 CPU오류 감지기능을 이용하여 SEU발생에 대처할 수 있는 시스템 레벨의 설계를 반영하고 있다.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.315-319
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• 2001

It is shown, that both cosmic radiation (external source) and natural radioactive gases (inner source) are sources of neutrons near the Earth crust. Correlation between the Earth crust dynamics and variations of thermal and slow neutron flux near the Earth surface is studied. It is shown, that variations of neutron flux near the Earth crust can be used for short-term predicting of natural hazards.

• 천문학회보
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• 제43권1호
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• pp.38.1-38.1
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• 2018

With upcoming high-quality data from surveys such as eBOSS or DESI, improving the theoretical modeling and gaining a deeper understanding of the effects of neutrinos and dark radiation on structure formation at small scales are necessary, to obtain robust constraints free from systematic biases. Using a novel suite of hydrodynamical simulations that incorporate dark matter, baryons, massive neutrinos, and dark radiation, we present a detailed study of their impact on Lyman-Alpha forest observables. In particular, we accurately measure the tomographic evolution of the shape and amplitude of the small-scale matter and flux power spectra and search for unique signatures along with preferred scales where a neutrino mass detection may be feasible. We then investigate the thermal state of the intergalactic medium (IGM) through the temperature-density relation. Our results indicate that the IGM at z ~ 3 provides the best sensitivity to active and sterile neutrinos.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2005년도 한국우주과학회보 제14권1호
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• pp.143-147
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• 2005

우주시스템 연구실에서 개발 중인 HAUSAT-2의 우주방사능 환경은 포획된 양자와 전자, 태양양성자이다. 본 논문에서는 우주방사능 환경에 대해 임무기간동안의 총 피폭량을 계산하였고, 총 피폭량에 대해 HAUSAT-2에서 사용하는 부품들의 부품의 우주방사능 허용레벨 분류과정을 통해 사용가능성을 검증하였다. 또한 단일사건 발생확률을 계산하여 단일사건 발생에 대비하는 시스템을 설계에 반영하였다.

• 한국환경보건학회지
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• 제46권1호
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• pp.96-102
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• 2020

Objectives: This study identified factors impacting radiation knowledge among aircrew, who are affected by cosmic radiation exposure due to their occupational environment. Methods: In September 2019 we conducted an online survey of aircrew through a Google link. We evaluated the level of radiation knowledge using a ten-item (10 points) questionnaire. The following exploratory variables were evaluated in relationship with the level of radiation knowledge using univariable linear regression models: sex, age, duration of employment, position level, company, marriage, education level, personal/family history of disease, and the number of times acquiring information on radiation through various channels (internet searching, watching television, reading newspaper, conversation about radiation with aircrew/non-aircrew, in-house training). With a p of 0.2 in univariable models, we built a multivariable linear regression model using a stepwise selection method. Results: The average radiation knowledge score of the 356 respondents was 7.22. Univariable linear regression analysis showed that radiation knowledge of the aircrew was associated with their company, position level, age, and number of conversations with other aircrew members. Our multivariable model showed that the radiation knowledge level of aircrew decreased as they had more conversations about radiation with other aircrew members and as their age increased. Conclusions: Korean air crew showed a lower level of radiation knowledge as their age and the number of conversations with colleagues increased. The study suggests that more education is needed in order for aircrew to gain accurate radiation knowledge.

• Journal of Astronomy and Space Sciences
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• 제10권2호
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• pp.103-112
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• 1993

The KITSAT-1 was successfully launched on August 11, 1992, into a near circular, 1300-km-high orbit with an $66^{\circ}$inclination. The satellite carries a solid state detector module to measure the high energy particle flux originating mostly from the inner radiation belt. We describe here the objectives of the experiment, the detector structure, and the preliminary result.

• 천문학논총
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• 제7권1호
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• pp.19-23
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• 1992

We investigated the "tilting" of the Universe, i.e., a non-Doppler origin of the dipole moment of the cosmic background radiation (CBR). Superhorizon-sized isocurvature, rotational and true vacuum bubble perturbations are considered. We show that the more natural way of the "tilting" the Universe is via the true vacuum bubble perturbation. Nevertheless, due to the small filling fraction of the bubbles of viable extended inflationary models, we find that the probability of the real occurrence in the Universe is quite insignificant.

• 천문학회보
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• 제42권2호
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• pp.55.2-55.2
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• 2017

We present a numerical code for the random scattering histories of Lyman alpha photons in the intergalactic medium. The numerical code calculates the radiative transfer under generic three dimensional density, ionization fraction, and peculiar velocity fields based on N-body + radiation transfer simulations of the epoch of reionization. The code is tested with models having analytical solutions, which have idealized geometry and simplified velocity fields. The emergent line profiles can give constraints to the ionization structure around Lyman alpha sources in the early universe.

• 천문학회보
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• 제35권2호
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• pp.42.2-42.2
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• 2010

The possibility of detection of deviation from Gaussian distribution of primordial perturbations in the Cosmic Microwave Background (CMB) Radiation is very important because it can shed light on how the perturbations were created in the very early universe. We study the effect of the primordal non-Gaussianity on topological observables called Minkowski Functionals, which are functions of the temperature fluctuation field, and show that they carry distinct signatures of different types of non-Gaussianities. Then, we constrain the non-Gaussianity parameters by comparing the theoretical predictions of the Minkowski Functionals with measurements from observational data from WMAP.

• 천문학논총
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• 제22권4호
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• pp.113-132
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• 2007

On the framework of stochastic gravitational wave background(SGWB) by compact binary systems, we studied the strain spectra of SGWB produced by cosmological cataclysmic variables(CV). For this we reviewed the empirical properties of CVs by using newly published CV catalogue and calculated the cosmological densities of CVs considering the galaxy luminosity function and cosmic stellar birth rate function. Assuming the secular evolution of CVs, we calculated the time scale of CV gravitational wave(GW) radiation and derived formulae for the strain spectra of SGWB by cosmological CVs.