• 한국정밀공학회지
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• 제22권12호
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• pp.100-107
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• 2005

The present work covers a new ray tracing scheme of an injection-molded plastic lens linked with finite element analysis fur injection molding processes. The traditional ray tracing schemes have been based on the assumption that optical property of the lens is homogeneous throughout the entire volume. However, this assumption is quite unrealistic for injection-molded plastic lenses since material properties vary at every point due to injection molding effects. In order to consider non-homogeneous property of a lens, a modified ray tracing method is proposed in connection with finite element analysis of injection molding. Through the analysis of the injection molding process, the distribution of refractive indices can be obtained. This information is then utilized in the proposed ray tracing scheme based on finite element meshes so as to take into account variation of the refractive indices. The effect of mold temperature is also investigated through finite element analysis, and the relevant optical quality is evaluated through the proposed ray tracing simulation.

• Journal of Plant Biology
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• 제13권2호
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• pp.15-20
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• 1970

The treatment of X-ray was manipulated with the large focus of X-ray which was produced the capacity of 90 kilovoltage and 30 milliamphere in the distance of 50 centimeter. The germination of each gruop irradiated with X-ray for 5, 6, and 7 seconds was more delayed in the growth of carrot seed than those of the control group. However the germination of each group irradiated with X-ray for 2, 3, and 4 seconds was rather accelerated than those of the control group. The irradiation of ultraviolet light was carried out in the distance of 20 centimeter by Toshiba germidicial lamp which appeared the wavelength of 2537A$^{\circ}$. The germination of each group irradiated with ultraviolet light for 9, 15, 20, and 40 minutes was more delayed than those of the control group, but the germination of carrot seed was accelerated by adequate dosage of ultraviolet light. Consuquently it was suggested for the author that the inhibited substance contained in carrot seed would be certain fatty substance, becasue the germination of carrot seed was more accelerated by the treatment of acetone than those of X-ray and ultraviolet light.

• 대한방사선기술학회지:방사선기술과학
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• 제30권3호
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• pp.245-250
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• 2007

진단용 방사선발생장치에서의 X선 에너지와 $^{99m}Tc$-MDP, $^{18}F$-FDG의 감마선 에너지 대한 apron 0.25, 0.5 mmPb에 대한 차폐율을 측정하였다. X선 에너지는 관전압 $40{\sim}120\;kVp$ 범위 내에서 부가여과판 0, 2 mmAl을 사용 한 경우에 실효에너지가 $26.2{\sim}45.6\;keV$로 측정되었으며, 이때 apron 0.5 mmPb은 0.25 mmPb보다 최대 선질에서 5.5% 정도 차폐율이 증가하였다. 또한 두 종류의 apron은 직접선과 공간선량률에 대하여 90% 이상의 높은 차폐율을 나타내었다. 그리고 $^{99m}Tc$-MDP의 140 keV에서 0.25, 0.5 mmPb apron을 사용할 경우 $30{\sim}53%$ 정도의 차폐효과가 있었으며, $^{18}F$-FDG의 511 keV의 높은 에너지에서는 $1.3{\sim}3.6%$로 apron의 차폐효과가 매우 적었다.

• 방사선산업학회지
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• 제9권1호
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• pp.1-7
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• 2015

The trend of x-ray image sensor has been evolved from an amorphous silicon sensor to a crystal silicon sensor. A crystal silicon X-ray sensor, meaning a X-ray CIS (CMOS image sensor), is consisted of three transistors (Trs), i.e., a Reset Transistor, a Source Follower and a Select Transistor, and a photodiode. They are highly sensitive to radiation exposure. As the frequency of exposure to radiation increases, the quality of the imaging device dramatically decreases. The most well known effects of a X-ray CIS due to the radiation damage are increments in the reset voltage and dark currents. In this study, a pixel array of a X-ray CIS was made of $20{\times}20pixels$ and this pixel array was exposed to a high radiation dose. The radiation source was Co-60 and the total radiation dose was increased from 1 to 9 kGy with a step of 1 kGy. We irradiated the small pixel array to get the increments data of the reset voltage and the dark currents. Also, we simulated the radiation effects of the pixel by MCNP (Monte Carlo N-Particle) simulation. From the comparison of actual data and simulation data, the most affected location could be determined and the cause of the increments of the reset voltage and dark current could be found.

• 지구물리와물리탐사
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• 제11권4호
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• pp.361-367
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• 2008

파선추적법을 이용하여 지진연구나 탄성파 탐사자료처리 또는 해석을 위해 합성탄성파기록을 작성하는 경우, 가장 다루기 힘들고 실수를 유발하기 쉬운 일 가운데 하나가 추적하고자하는 파선들의 전파경로를 하나하나 지정해주는 것이다. 주어진 음원으로부터 수진기에 도달하는 무수히 많은 파 중에서 중요한 위상들에 대한 파선경로를 누락하거나, 잘못 지정하는 경우에 해석상의 커다란 오류를 가져올 수 있기 때문에 파선추적법에서 이는 아주 중요한 문제이다. 본 연구에서는 이와 같은 문제점을 해결하기 위해 음원이나 수진기가 지표상 또는 임의의 지층 내에 위치한 경우에도 주어진 모델에 대해 음원과 수진점을 잇는 모든 전파경로를 빠짐없이 체계적으로 생성해주는 알고리즘을 개발하였다. 본 연구에서 개발된 알고리즘은 탄성파탐사 자료해석 시 다중반사파 특성파악, 다중반사파 제거연구 및 지진분야에서는 코다 파(coda wave) 특성연구, 분지에서의 지진파 증폭효과 연구, 모드 변환된 다중반사파의 위상식별 등에 효과적으로 이용될 수 있을 것이다.

• 천문학회보
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• 제38권2호
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• pp.96.1-96.1
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• 2013

A Forbush decrease(FD) is a depression of cosmic ray intensity observed by ground-based neutron monitors(NMs). The cosmic ray intensity is thought to be modulated by the heliospheric magnetic structures including the interplanetary coronal mass ejection(ICME) surrounding the Earth. The different magnitude of the decreasing in intensity at each NM was explained only by the geomagnetic cutoff rigidity of NM station. However, sometimes NMs of the almost same rigidity in northern and southern hemispheres observe the asymmetric intensity depression magnitudes of FD events. Thus, in this study we intend to see the effects on cosmic ray intensity depression rate of FD event recorded at different NMs due to different ICME propagation direction as an additional parameter in the model explaining the cosmic ray modulation. Fortunately, since 2006 the coronagraphs of twin spacecraft of the STEREO mission allow us to infer the propagation direction of ICME associated with the FD event in 3-dimension with respect to the Earth. We confirm that the asymmetric cosmic ray decreasing modulations of FD events are determined by the propagation directions of the associated ICMEs.

• Natural Product Sciences
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• 제19권2호
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• pp.127-136
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• 2013

Ionizing radiation, including that evoked by gamma (${\gamma}$)-rays, induces oxidative stress through the generation of reactive oxygen species, resulting in apoptosis, or programmed cell death. This study aimed to elucidate the radioprotective effects of hyperoside (quercetin-3-O-galactoside) against ${\gamma}$-ray radiation-induced apoptosis in Chinese hamster lung fibroblasts, V79-4 and demonstrated that the compound reduced levels of intracellular reactive oxygen species in ${\gamma}$-ray-irradiated cells. Hyperoside also protected irradiated cells against DNA damage (evidenced by pronounced DNA tails and elevated phospho-histone H2AX and 8-oxoguanine content) and membrane lipid peroxidation. Furthermore, hyperoside prevented the ${\gamma}$-ray-provoked reduction in cell viability via the inhibition of apoptosis through the increased levels of Bcl-2, the decreased levels of Bax and cytosolic cytochrome c, and the decrease of the active caspase 9 and caspase 3 expression. Taken together, these results suggest that hyperoside defend cells against ${\gamma}$-ray radiation-induced apoptosis by inhibiting oxidative stress.

• Journal of Plant Biology
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• 제5권1호
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• pp.1-6
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• 1962

1) Germination rate was rather irregular than decreasing as increasing dose of radiation and there were no differences between Kyong-Sam and Chuong-Bang of Chinese cabbage. 2) In R1 generation, abnormal leaves from seedling of irradiated seeds were observed. These were more apparent in X-ray irradiation than in thermal neutron. 3) Seedling height was inhibited with increasing dose of X-ray and thermal neutrons. Growth inhibition was more remarkable in X-ray than in thermal neutron. Kyong-Sam demonstrated more sensitivity than Chyong-Bang in both X-ray and thermal neutron. 4) Seedling height produced from seeds subjected to thermal neutrons showed small variation around its mean value, while in X-irradiation there was a greater deviaton from the mean value. 5) Fertility was decreased as increasing with dose, while the frequency of abortive pollen was increased. There were variability of the fertility and frequency of abortive pollen among plants or branches of a plant. 6) The mutants were obtained more in thermal neutron irradiation than in X-ray. The types of mutations obtained in Chinese radish of R2 generation were abnormal leaf, densely glowing leaf, degeneration in growing point and dwarf. The maximum frequency of phenotypic mutations was abnormal leaf mutation.

• 방사선산업학회지
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• 제6권1호
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• pp.17-21
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• 2012

The effects of gamma ray or electron beam irradiation on herbaceous medicinal plants were investigated in terms of the composition of volatile constituents using the aerial parts or leaves of Artemisia princeps Pamp. cv. Ganghwayakssuk and Artemisia argyi cvs. Namhaeyakssuk and Hwanghaessuk. The composition of volatile constituents in leaves was clearly distinguishable among the three Artemisia cultivars. However, the relative proportions of the major volatile constituents such as 1,8-cineole, ${\alpha}$-pinene, camphene, santolina triene, and artemesia triene, were similarly changed in two or three cultivars by gamma ray or electron beam irradiation. In particular, the proportion of 1,8-cineole was increased up to 1.29- to 1.71-fold in the three cultivars after irradiation with gamma ray. These results suggest that gamma ray or electron beam irradiation can be applied to modulate the composition of volatile constituents in the leaves of Artemisia plants.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3401-3408
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• 2023

In this study, we used the Monte Carlo N-Particle program to simulate the gamma-ray spectra obtained from plastic scintillators holes filled with bismuth nanoparticles. We confirmed that the incorporation of bismuth nanoparticles into a plastic scintillator enhances its performance for gamma-ray spectroscopy using the subtraction method. The subtracted energy spectra obtained from the bismuth-nanoparticle-incorporated and the original plastic scintillator exhibit a distinct energy peak that does not appear in the corresponding original spectra. We varied the diameter and depth of the bismuth-filled holes to determine the optimal hole design for gamma-ray spectroscopy using the subtraction method. We evaluated the energy resolutions of the energy peaks in the gamma-ray spectra to estimate the effects of the bismuth nanoparticles and determine their optimum volume in the plastic scintillator. In addition, we calculated the peak-to-total ratio of the energy spectrum to evaluate the energy measuring limit of the bismuth nanoparticle-containing plastic scintillator using the subtraction method.