• 한국항공운항학회지
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• 제26권2호
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• pp.91-97
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• 2018

High-energy charged particles are comprised of galactic cosmic rays and solar energetic particles which are mainly originated from the supernova explosion, active galactic nuclei, and the Sun. These primary charged particles which have sufficient energy to penetrate the Earth's magnetic field collide with the Earth's upper atmosphere, that is $N_2$ and $O_2$, and create secondary particles and ionizing radiation. The ionizing radiation can be measured at commercial flight altitude. So it is recommended to manage radiation dose of aircrew as workers under radiation environment to protect their health and safety. However, it is hard to deploy radiation measurement instrument to commercial aircrafts and monitor radiation dose continuously. So the numerical model calculation is performed to assess radiation exposure at flight altitude. In this paper, we present comparison result between measurement data recorded on several flights and estimation data calculated using model and examine the characteristics of the radiation environment in the atmosphere.

• 한국방사선학회논문지
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• 제17권3호
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• pp.367-373
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• 2023

비행시 승무원이나 승객은 우주방사선과 공기나 비행기 기체와 반응하여 발생한 2차 산란선 등에 의해 피폭을 받게 된다. 항공기 승무원의 경우 우주기상 환경 시뮬레이션을 이용하여 계산된 피폭선량으로 방사선 안전관리를 적용받고 있다. 하지만, 태양활동이나 고도, 비행경로 등에 따라 피폭선량이 가변적이어서 계산법보다는 항로별 측정하는 것이 권고되고 있다. 본 연구에서는 범용 Si 센서와 다중채널파고분석기를 이용하여 우주방사선 선량을 측정할 수 있는 선량계를 개발하였다. 선량계산은 미우주항공국의 우주방사선 측정장비인 CRaTER(Cosmic Ray Telescope for the Effects of Radiation)의 알고리즘을 적용하였다. 표준교정시설에서 Cs-137 662 keV 감마선으로 에너지 및 선량교정을 시행하였으며, 실험 범위에서 선량률 의존성이 없음을 확인하였다. 제작된 선량계를 이용하여 2023년 5월 두바이 인천 구간의 국제선에서 직접 선량을 측정한 결과 국내 우주방사선 선량평가코드(KREAM; Korean Radiation Exposure Assessment Model for Aviation Route Dose)로 계산된 결과와 12% 이내로 비슷하게 나타났으며, 고도와 위도가 높아짐에 따라 계산 결과와 동일하게 선량이 증가하는 것을 확인하였다. 좀 더 많은 실증적 검증 실험이 요구되는 제한점은 있지만, 항공기 내 또는 개인 피폭선량 모니터링에 가성비가 우수한 선량계로 충분한 활용 가능성을 확인하였다.

• 천문학회보
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• 제46권2호
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• pp.72.2-72.2
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• 2021

Cosmic reionization imprints its history on the sky map of the cosmic microwave background (CMB) polarization. Even though mild, the signature of the reionization history during its early phase (z>15) can also impact the CMB polarization. We forecast the observational capability of the LiteBIRD(Lite(Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection), a truly cosmic-variance limited apparatus. We focus on the capability for such an apparatus to probe the partial optical depth of the CMB photons during z>15. We show that LiteBIRD is able to probe this quantity with a modest to high significance, enabling one to tell how efficient the cosmic reionization and star formation were at z>15.

• Journal of Photoscience
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• 제9권2호
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• pp.170-173
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• 2002

Space is full of energetic events emitting high-energy radiations which may be fatal to all living things unless protected. The present paper briefly describes high-energy photons and particles incident on Earth surface and their common properties toward living things. Role of radiation played in evolution of life and earth environment will be presented.

• Journal of Radiation Protection and Research
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• 제14권2호
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• pp.51-62
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• 1989

The high efficiency moderated-type neutron spectrometer and doseequivalent counter were developed for the measurement of low level environmental neutrons. By using these detectors, the neutron energy spectra and dose equivalent rates due to skyshine effect were measured in the environment surrounding the accelerator facilities and also the altitude variation of cosmic ray neutrons in the aircraft flying over Japan.

• 천문학회지
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• 제48권1호
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• pp.9-20
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• 2015

We study the evolution of the energy spectrum of cosmic-ray electrons accelerated at spherically expanding shocks with low Mach numbers and the ensuing spectral signatures imprinted in radio synchrotron emission. Time-dependent simulations of diffusive shock acceleration (DSA) of electrons in the test-particle limit have been performed for spherical shocks with parameters relevant for typical shocks in the intracluster medium. The electron and radiation spectra at the shock location can be described properly by the test-particle DSA predictions with instantaneous shock parameters. However, the volume integrated spectra of both electrons and radiation deviate significantly from the test-particle power-laws, because the shock compression ratio and the flux of injected electrons at the shock gradually decrease as the shock slows down in time. So one needs to be cautious about interpreting observed radio spectra of evolving shocks based on simple DSA models in the test-particle regime.

• 전자통신동향분석
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• 제37권2호
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• pp.21-29
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• 2022

Cosmic radiation environments having extremely high-energy particles and photons cause severe malfunctions of electrical components in space and terrestrial regions. In this study, we revisit basic knowledge on radiation effects in ICT electrical devices, such as single event effect, total ionizing dose, and displacement damage. To avoid such soft errors and system failures, we introduce essential technical approaches from the perspectives of materials, layouts, circuits, and systems, including current research trends. By considering several techniques and Space EEE part standards, we suggest possible directions that can invoke New Space Era technology.

• 천문학회보
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• 제35권1호
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• pp.83.2-83.2
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• 2010

During the formation of cosmic web, collisionless shock waves are produced around and inside the substructures. In these shock waves electrons and ions are accelerated to such high energies that they can produce gamma rays in several ways. Many authors have studied the contribution of shock-induced radiation to the cosmic gamma-ray background. However not all the important physical processes are included in their calculation. By considering more complete physical process, we re-investigate the problem. In our model, the energy distribution of the cosmic rays (CRs) are calculated by widely accepted diffusive shock acceleration model, both primary and secondary CR electrons are included, both inverse Compton scattering and bremsstrahlung process are considered. The difference of the results are discussed.

• 천문학회보
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• 제33권1호
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• pp.86.1-86.1
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• 2008

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 춘계공동학술발표회요약집
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• pp.421.1-421
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• 2002