• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.23.1-23.1
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• 2008

A space shuttle with a Prototype Synchrotron Radiation Detector (PSRD) was launched in 2001. PSRD was set in the Endeavour payloads and got data for 12 days. The purpose of PSRD is to measure synchrotron photons which are created by high energy charged particles near earth. Synchrotron photons are confused with background photons. We studied how to separate synchrotron photons from backgrounds.

• 환경생물
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• 제35권4호
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• pp.622-630
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• 2017

본 연구에서는 다양한 온도(5, 10, 15 and $20^{\circ}C$), 조도(5, 10, 20 and $40{\mu}mol\;photons\;m^{-2}\;s^{-1}$) 및 광주기(14 : 10, 12 : 12 and 10 : 14 h L : D) 조건에서 미역 배우체의 분리, 재생 및 성숙 조건을 파악하였다. 암배우체 단편은 $15^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D) 조건에서 빠른 생장을 보인 반면 수배우체는 $15^{\circ}C$, $5{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 14 : 10 h (L:D) 조건에서 빠른 생장을 보여 차이를 나타냈다. 암수배우체의 최적 성숙 조건은 각각 $5^{\circ}C$, $20{\sim}40{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D) 조건과 $15^{\circ}C$, $40{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10 : 14 h (L: D) 조건이었다. 본 연구 결과 확인된 미역 유리배우체의 재생과 성숙 조건은 미역의 형질개선과 교잡 육종 등을 위한 기초자료로 활용될 수 있다.

• 환경생물
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• 제36권4호
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• pp.576-583
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• 2018

본 연구에서는 다양한 온도(5, 10, 15, 20, $25^{\circ}C$), 조도(10, 20, 40, 60, $80{\mu}mol\;photons\;m^{-2}\;s^{-1}$) 및 광주기(10:14, 12:12, 14:10 h L:D) 조건에서 개다시마 유리배우체 단편의 생장 및 성숙 유도조건을 파악하였다. 암배우체 단편의 생장은 $20^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10:14 h (L:D) 조건에서 빠른 생장을 보인 반면 수배우체는 $15^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 14:10 h (L:D) 조건에서 빠른 생장을 보여 차이를 나타내었다. 암배우체의 최적 성숙조건은 $15^{\circ}C$, $40{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 14:10 h (L:D) 조건에서 가장 빠른 성숙을 보인 반면 수배우체는 $10^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10:14 h (L:D) 조건에서 빠른 성숙을 보여 차이를 나타내었다. 본 연구 결과 확인된 개다시마 유리배우체 단편의 생장 및 성숙조건은 개다시마의 자원조성 및 대량양식 기반조성의 기초자료로 활용될 수 있다.

• 한국컴퓨터그래픽스학회논문지
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• 제16권3호
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• pp.41-48
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• 2010

포톤 매핑은 대표적인 전역 조명 방법으로써 광원에서 많은 수의 포톤을 방출하여 이를 이용해 사실적인 렌더링을 수행한다. 하지만 매우 많은 수의 포톤을 추적하기 때문에 실시간 렌더링이 힘들고 많은 양의 메모리를 사용하는 문제가 있다. 이러한 문제를 개선한 방법이 점진적 포톤 매핑이다. 기존의 점진적 포톤 매핑은 먼저 광선 추적법을 통해 각 광선과 물체와의 충돌 위치를 찾는다. 다음으로 포톤 추적 단계에서는 반복적으로 적은 수의 포톤을 방출하고, 충돌 위치를 중심으로 하며 고정된 반지름을 가지는 구 안에 들어오는 포톤으로 포톤의 밝기를 누적한다. 이 방법은 포톤 매핑보다 자원을 적게 소모하지만, 방출된 포톤이 임의의 방향으로 진행하기 때문에 충분한 포톤을 확보하고 부드러운 영상을 렌더링하기 위해 많은 시간이 필요하다. 이를 보완하기 위해 본 논문에서는 포톤 탐사 단계를 추가하여 구 안에 들어오는 포톤들의 분포를 계산하고 그에 따라 구의 반지름을 조절하는 방법을 제안한다. 또한 래디언스 추정 과정에 콘 필터를 적용하여 영상을 선명히 렌더링한다.

• 천문학회보
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• 제46권2호
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• pp.40.1-40.1
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• 2021

Hydrogen is the most abundant element in the universe, which is, in the cosmological context, attributed to its simplest structure consisting of a proton and an electron. Hydrogen interacts with an electromagnetic wave in astrophysical environments. Rayleigh scattering refers to elastic scattering, where the frequencies of the incident and scattered photons are the same. Rayleigh and resonance scattering is a critical role study Lyman Alpha objects in the early universe. The scattering causes the frequency and spatial diffusion of Lyα. In the case of Raman scattering, the energies of the incident and scattered photons are different. The photons near Lyβ convert to the optical photons near Hα through Raman scattering. The photon scattered by atomic hydrogen can carry both of the properties of the H I region and the emission region. I adopt a Monte Carlo approach to investigate the formation of the various spectral line features through Rayleigh and Raman scattering in highly thick media of atomic hydrogen. In this thesis, I present my works on radiative transfer involving the scattering processes between far UV photon and atomic hydrogen. I introduce scattering processes with atomic hydrogen and the spectral, spatial, and polarized information originating from the scattering.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1633-1637
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• 2019

While considering the photon attenuation coefficient (${\mu}$) and its related parameters for photons shielding, it is necessary to account for its transmitted and reflected photons energy spectra and dose contribution. Monte Carlo simulation was used to study the efficiency of clay ($1.99g\;cm^{-3}$) as a shielding material below 150 keV photon. Am-241 gamma source and an X-ray of 150 kVp were calculated. The calculated value of ${\mu}$ for Am-241 is higher within 5.61% compared to theoretical value for a single-energy photon. The calculated half-value layer (HVL) is 0.9335 cm, which is lower than that of ordinary concrete for X-ray of 150 kVp. A thickness of 2 cm clay was adequate to attenuate 90% and 85% of the incident photons from Am-241 and X-ray of 150 kVp, respectively. The same thickness of 2 cm could shield the gamma source dose rate of Am-241 (1 MBq) down to $0.0528{\mu}Sv/hr$. For X-ray of 150 kVp, photons below 60 keV were significantly decreased with 2 cm clay and a dose rate reduction by ~80%. The contribution of reflected photons and dose from the clay is negligible for both sources.

• 한국재료학회지
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• 제32권10호
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• pp.419-424
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• 2022

Halide perovskite solar cells (PSCs) have improved rapidly over the past few years, and research on the optoelectrical properties of halide perovskite thin films has grown as well. Among the characterization techniques, photoluminescence (PL), a method of collecting emitted photons to evaluate the properties of materials, is widely applied to evaluate improvements in the performance of PSCs. However, since only photons emitted from the film in the escape cone are included, the photons collected in PL are a small fraction of the total photons emitted from the film. Unlike PSCs power conversion efficiency, PL measuring methods have not been standardized, and have been evaluated in a variety of ways. Thus, an in-depth study is needed of the methods used to evaluate materials using PL spectra. In this study, we examined the PL spectra of the perovskite light harvesting layer with different measurement protocols and analyzed the features. As the incident angle changed, different spectra were observed, indicating that the PL emission spectrum can depend on the measuring method, not the material. We found the intensity and energy of the PL spectra changes were due to the path of the emitted photons. Also, we found that the PL of halide perovskite thin films generally contains limited information. To solve this problem, the emitted photons should be collected using an integrating sphere. The results of this study suggest that the emission spectrum of halide perovskite films should be carefully interpreted in accordance with PL measuring method, since PL data is mostly affected by the method.

• 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.

• 한국수산과학회지
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• 제49권2호
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• pp.190-197
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• 2016

We examined for differences in the growth and fertility of microscopic stages between Costaria costata and Undaria pinnatifida in crossed temperature×irradiance (12, 17, 22℃×20, 60 μmol photons m^–2s^–1) and daylength×irradiance (8, 12, 16, 24 h×20, 60 μmol photons m^–2s^–1) experimental designs. After 13 days in culture, maximum gametophyte growths of the two species were obtained under the following combinations of factors: 17℃×60 μmol photons m^–2s^–1 and 24 h daylength×60 μmol photons m^–2s^–1. C. costata gametophytes produced sporophytes about 6 days earlier than those of U. pinnatifida. Sporophyte densities were highest in the 12 h daylength×60 μmol photons m^–2s^–1 combination after 20 days in C. costata (9.7 plants mm^–2) and 26 days in U. pinnatifida (9.1 plants mm^–2). However, optimal growth conditions for the microscopic sporophytes differed between species: 17℃×60 μmol photons m^–2 s^–1 for C. costata, 12℃×60 μmol photons m^–2 s^–1 for U. pinnatifida. Thus, C. costata gametophytes grew faster and produced sporophytes earlier than those of U. pinnatifida, even though the haploid gametophytes of the two species responded similarly to environmental conditions. Optimal growth temperatures for the microscopic sporophytes also differed between species.

• Asian Pacific Journal of Cancer Prevention
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• 제16권17호
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• pp.7785-7788
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• 2015

Utilization of high energy photons (>10MV) with an optimal weight using a mixed energy technique is a practical way to generate a homogenous dose distribution while maintaining adequate target coverage in intact breast radiotherapy. This study represents a model for estimation of this optimal weight for day to day clinical usage. For this purpose, treatment planning computed tomography scans of thirty-three consecutive early stage breast cancer patients following breast conservation surgery were analyzed. After delineation of the breast clinical target volume (CTV) and placing opposed wedge paired isocenteric tangential portals, dosimeteric calculations were conducted and dose volume histograms (DVHs) were generated, first with pure 6MV photons and then these calculations were repeated ten times with incorporating 18MV photons (ten percent increase in weight per step) in each individual patient. For each calculation two indexes including maximum dose in the breast CTV ($D_{max}$) and the volume of CTV which covered with 95% Isodose line ($V_{CTV,95%IDL}$) were measured according to the DVH data and then normalized values were plotted in a graph. The optimal weight of 18MV photons was defined as the intersection point of $D_{max}$ and $V_{CTV,95%IDL}$ graphs. For creating a model to predict this optimal weight multiple linear regression analysis was used based on some of the breast and tangential field parameters. The best fitting model for prediction of 18MV photons optimal weight in breast radiotherapy using mixed energy technique, incorporated chest wall separation plus central lung distance (Adjusted R2=0.776). In conclusion, this study represents a model for the estimation of optimal beam weighting in breast radiotherapy using mixed photon energy technique for routine day to day clinical usage.