스마트칩 카드을 이용한 광 자극 발광 특성 연구

박상원(Sang-Won Park),유세종(Se-Jong Yoo) 대한방사선과학회(구 대한방사선기술학회) 2019 방사선기술과학 Vol.42 No.5

Radiation is used for various purposes such as cancer therapy, research of industrial and drugs. However, in case of radiation accidents such as terrorism, collapsing nuclear plant by natural disasters like Fukushima in 2011, very high radiation does expose to human and could lead to death. For this reason, many people are concerning about radiation exposures. Therefore, assessment and research of retrospective radiation dose to human by various path is an necessary task to be continuously developed. Radiation exposure for workers in radiation fields can be generally measured using a personal exposure dosimeter such as TLD, OSLD. However, general people can’t be measured radiation doses when they are exposed to radiation. And even if radiation fields workers, when they do not in possession personal dosimeter, they also can’t be measured exposure dose immediately. In this study, we conduct retrospective research on reconstruction of dose after exposure by using smart chip card of personal items through Optically Stimulated Luminescence (OSL). The OSL signal of smart chip card shows linear response from 0.06 Gy to 15 Gy and results of fading rate 45 %, 48% for 24 and 48 hours due to the natural emission of radiation in sample, respectively. The minimum detectable limit (MDD) was 0.38 mGy. This values are expected to use as correction values for reconstruction of exposure dose.

Development and Characterization of the Integrated Fiber-optic Sensor for Remote Detection of Alpha Radiation

박찬희,문주현,서범경 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.9

In this study, we developed and characterized an integrated fiber-optic sensor for the remotedetection of alpha radiation emitted from radioactive contamination in areas relatively inaccessibleby radiation workers. The fiber-optic sensor consisted of an epoxy-resin supporter and a sensingprobe attached to it. The epoxy-resin supporter to hold the optical fiber tightly was fabricated byusing epoxy-resin and a small amount of hardener. The sensing probe was fabricated by mixingepoxy-resin with inorganic scintillator ZnS(Ag) powder and solidifying the mixture. Then, thesensing probe was attached to the epoxy-resin supporter. As a light guide, an optical fiber, whichwas also compatible with the epoxy-resin, was used. The optical fiber was submerged in the epoxyresinsupporter before solidification to make it in an integral form to minimize the loss of scintillationlight due to incomplete connections between them. The four assembled fiber-optic sensors withsensing probes whose density thicknesses of ZnS(Ag) were 10, 15, 20 and 25 mg/cm2, respectively,were evaluated in terms of the total counts of alpha radiation to determine the optimum densitythickness of ZnS(Ag). From the evaluation, a density thickness of 15 mg/cm2 was found to be thebest for detecting alpha radiation.

사용후핵연료 집합체 모사장치를 이용한 광섬유 체렌코프 방사선 센서 시스템의 성능평가

신상훈 ( Sang Hun Shin ),유욱재 ( Wook Jae Yoo ),장경원 ( Kyoung Won Jang ),조승현 ( Seung Hyun Cho ),박병기 ( Byung Gi Park ),이봉수 ( Bong Soo Lee ) 한국센서학회 2014 센서학회지 Vol.23 No.4

When the charged particle travels in transparent medium with a velocity greater than that of light in the same medium, the electromagnetic field close to the particle polarizes the medium along its path, and then the electrons in the atoms follow the waveform of the pulse which is called as Cerenkov light or radiation. This type of radiation can be easily observed in a spent fuel storage pit. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, simulated spent fuel assembly and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the intensities of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, we measured the longitudinal distribution of gamma rays emitted from the Ir-192 isotope by using the fiber-optic Cerenkov radiation sensor system and simulated spent fuel assembly.

Rationale and Definition of The Criteria of The Efficiency of The Biological Activity of Optical Radiation on Animal Organism.

Chervinsky, Leonid S. Korea FoodHealth Convergence Association 2018 식품보건융합연구 (KJFHC) Vol.4 No.3

In today's technological development of human society more and more influence on the lives of biological organisms different electromagnetic radiation. Therefore, the study and analysis of the mechanisms of their effects is an urgent task. The purpose of research - the study of the primary mechanisms of interaction of photons of optical radiation with the structures of biological objects, using the laws of quantum mechanics and biophysics. Photobiological basis of the mechanism of action of EMR optical range is the energy absorption of light quanta (photons) by atoms and molecules of biological structures (law Grotgus-Draper), which resulted in the formation of electronically excited states of these molecules with the transfer of photon energy (internal photoeffect). This is accompanied by electrolytic dissociation and ionization of biological molecules. The degree of manifestation of photobiological effects in the body depends on the intensity of the optical radiation, which is inversely proportional to the square of the distance from the source to the irradiated surface. Accordingly, in practice, determine not the intensity and irradiation dose at a certain distance from the source of exposure by the exposure time.

Usefulness of a Small-Field Digital Mammographic Imaging System Using Parabolic Polycapillary Optics as a Diagnostic Imaging Tool: a Preliminary Study

천권수,박정곤,박성훈,강성훈,김혜원,손현화,김혜원,김헌수,윤권하 대한영상의학회 2009 Korean Journal of Radiology Vol.10 No.6

Objective: To evaluate the efficacy for spatial resolution and radiation dose of a small-field digital mammographic imaging system using parabolic polycapillary optics. Materials and Methods: We developed a small-field digital mammographic imaging system composed of a CCD (charge coupled device) detector and an Xray source coupled with parabolic polycapillary optics. The spatial resolution and radiation dose according to various filters were evaluated for a small-field digital mammographic imaging system. The images of a test standard phantom and breast cancer tissue sample were obtained. Results: The small-field digital mammographic imaging system had spatial resolutions of 12 lp/mm with molybdenum and rhodium filters with a 25-μm thickness. With a thicker molybdenum filter (100 μm thick), the system had a higher spatial resolution of 11 lp/mm and contrast of 0.48. The radiation dose for a rhodium filter with a 25-μm thickness was 0.13 mGy within a 10-mm-diameter local field. A larger field image greater than 10 mm in diameter could be obtained by scanning an object. On the small-field mammographic imaging system, microcalcifications of breast cancer tissue were clearly observed. Conclusion: A small-field digital mammographic imaging system with parabolic polycapillary optics may be a useful diagnostic tool for providing high-resolution imaging with a low radiation dose for examination of local volumes of breast tissue. Objective: To evaluate the efficacy for spatial resolution and radiation dose of a small-field digital mammographic imaging system using parabolic polycapillary optics. Materials and Methods: We developed a small-field digital mammographic imaging system composed of a CCD (charge coupled device) detector and an Xray source coupled with parabolic polycapillary optics. The spatial resolution and radiation dose according to various filters were evaluated for a small-field digital mammographic imaging system. The images of a test standard phantom and breast cancer tissue sample were obtained. Results: The small-field digital mammographic imaging system had spatial resolutions of 12 lp/mm with molybdenum and rhodium filters with a 25-μm thickness. With a thicker molybdenum filter (100 μm thick), the system had a higher spatial resolution of 11 lp/mm and contrast of 0.48. The radiation dose for a rhodium filter with a 25-μm thickness was 0.13 mGy within a 10-mm-diameter local field. A larger field image greater than 10 mm in diameter could be obtained by scanning an object. On the small-field mammographic imaging system, microcalcifications of breast cancer tissue were clearly observed. Conclusion: A small-field digital mammographic imaging system with parabolic polycapillary optics may be a useful diagnostic tool for providing high-resolution imaging with a low radiation dose for examination of local volumes of breast tissue.

Development of a Liquid-Crystal-Based Real-Time Radiation Dosimeter Based on Electro Optical Light Modulation

허예지,Kyotae Kim,Sang Hee Nam,Sung-Kwang Park,Si Cheul Noh,Sang Sick Kang,Ji-Koon Park 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.5

This study evaluates the feasibility of a radiation dosimeter that can monitor radiation exposure in real time based on the electro optical modulation of a liquid crystal (LC) cell and the photoconductor cadmium sulfide (CdS). Cadmium sulfide (CdS) is often used in photosensors because of its high reproducibility and sensitivity to light and radiation. As basic research, the electro optical features of a LC cell and a novel CdS photosensor were analyzed from the viewpoint of fabricating a radiation dosimeter. Based on the results, the feasibility of such a detection device was studied by analyzing the efficiency of its electro optical light modulation. The measurement results suggested that the detection system had high resolution and very good reproducibility, with CdS showing excellent Xray detection efficiency. The results suggest that noise reduction can be achieved by incorporating an LC, given its static electric features. The results of this study could help realize real-time portable radiation dosimeter systems based on optical modulation and using a CdS photosensor.

Gamma-Ray Irradiation-Induced Optical Attenuation in Co/Fe Co-Doped Alumino-Silicate Optical Fiber for Dosimeter Application

Youngwoong Kim,Seongmin Ju,Seongmook Jeong,Jong-Yeol Kim,Nam-Ho Lee,Hyun-Kyu Jung,Won-Taek Han IEEE 2014 Journal of Lightwave Technology Vol.32 No.22

<P>Dose dependence of radiation-induced optical attenuation (RIA) at 1310 nm of the Co/Fe co-doped alumino-silicate optical fiber was investigated under gamma-ray irradiation at dose rates from 6.7 to 78.3 Gy/min. From the measured RIA, radiation dose sensitivity (ΔRIA/ΔDose) and rate of RIA change with irradiation time (ΔRIA/ΔTime) at the different dose rates were estimated. RIAs at various wavelengths (800 to 1600 nm) of the optical fiber were also measured and the RIA characteristics at 800 and 1310 nm under discrete gamma-ray irradiation were investigated. The measured RIA of the Co/Fe co-doped fiber showed very high dose sensitivity regardless of the dose rates and the ΔRIA/ΔTime was found to show linear response with respect to the dose rate. The significantly large RIA was attributed to Co, Fe, and Al-related defects in the fiber core which were formed by the irradiation, and it became larger at shorter wavelength. The high radiation dose sensitivity, linear response of the ΔRIA/ΔTime with respect to dose rate, and the high reproducibility of the dose dependence of RIA under the discrete irradiation clearly indicate that the Co/Fe co-doped fiber is able to provide highly accurate information of not only total accumulated dose but also dose rate of the radiation with irradiation time.</P>

Optical Tunneling Mediated Sub-Skin-Depth High Emissivity Tungsten Radiators

Cho, Jin-Woo,Lee, Kyung-Jun,Lee, Tae-Il,Kim, Young-Bin,Choi, Dae-Geun,Nam, Youngsuk,Kim, Sun-Kyung American Chemical Society 2019 NANO LETTERS Vol.19 No.10

<P>Tailoring the spectrum of thermal radiation at high temperatures is a central issue in the study of thermal radiation harnessed energy resources. Although bulk metals with periodic cavities incorporated into their surfaces provide high emissivity, they require a complicated micron metal etch, thereby precluding reliable, continuous operation. Here, we report thermally stable, highly emissive, ultrathin (<20 nm) tungsten (W) radiators that were prepared in a scalable and cost-effective route. Alumina/W/alumina multiwalled, submicron cavity arrays were fabricated sequentially using nanoimprinting lithography, thin film deposition, and calcination processes. To highlight the practical importance of high-temperature radiators, we developed a thermophotovoltaic (TPV) system equipped with fabricated W radiators and low-bandgap GaSb photovoltaic cells. The TPV system produced electric power reliably during repeated temperature cycling between 500 and 1200 K; the power density at 1200 K was fixed to be approximately 1.0 W/cm<SUP>2</SUP>. The temperature-dependent electric power was quantitatively reproduced using a one-dimensional energy conversion model. The symmetric configuration of alumina/W/alumina multiwall together with the presence of a void inside each cavity alleviated thermal stress, which was responsible for the stable TPV performance. The short-current-density (<I>J</I><SUB>SC</SUB>) of developed TPV system was augmented significantly by decreasing the W thickness below its skin depth. A 17 nm thick W radiator yielded a 32% enhancement in <I>J</I><SUB>SC</SUB> compared to a 123 nm thick W radiator. Electromagnetic analysis indicated that subskin-depth W cavity arrays led to suppressed surface reflection due to the mitigated screening effect of free electrons, thereby enhancing the absorption of light within each W wall. Such optical tunneling-mediated absorption or radiation was valid for any metal material and morphology (e.g., planar or patterned).</P> [FIG OMISSION]</BR>

Fundamental Research on a Cerenkov Radiation Sensor Based on Optical Glass for Detecting Beta-rays

김재석,장경원,신상헌,전다영,홍성한,심혁인,김선근,유욱재,이봉수,문주현,박병기 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.1

In this study, a Cerenkov radiation sensor for detecting low-energy beta-particles was fabricatedusing various Cerenkov radiators such as an aerogel and CaF2-, SiO2-, and Al2O3-based opticalglasses. Because the Cerenkov threshold energy (CTE) is determined by the refractive index ofthe Cerenkov radiator, the intensity of Cerenkov radiation varies according to the refractive indicesof the Cerenkov radiators. Therefore, we measured the intensities of Cerenkov radiation inducedby beta-particles generated from a radioactive isotope as a function of the refractive indices of theCerenkov radiators. Also, the electron fluxes were calculated for various Cerenkov radiators byusing a Monte Carlo N-Particle extended transport code (MCNPX) to determine the relationshipbetween the intensities of the Cerenkov radiation and the electron fluxes.

대전 지역 UV-A 자외선 복사량을 이용한 GK-2A와 HIMAWARI 위성의 구름 광학 두께 비교

이동규,김창기,염성수,김현구,강용혁 한국태양에너지학회 2023 한국태양에너지학회 논문집 Vol.43 No.3

Cloud optical thickness, also known as cloud optical depth, is an indicator that quantitatively shows the attenuation effect of solar radiance by clouds in the atmosphere and is calculated through statistical models or the radiative transfer model of each satellite using its observation data and ancillary data. Therefore, even for observations performed at the same location and time, the retrieved COT differ from satellite to satellite. Thus, this study aims to verify the retrieved COT of the GK-2A and HIMAWARI satellites, which are Korean and Japanese geostationary satellites, respectively, covering the Korean Peninsula. To verify the COT data, the method used by Qin et al. (2019) was used, where the COT was indirectly verified by calculating downward radiation using satellite-retrieved data such as COT, cloud phase, and cloud top pressure as parameters and comparing this with ground-observed radiation. In this study, a radiative transfer model, libRadtran 2.0.4, was used to calculate UV-A radiation and compare it with observed data in Daejeon as the true value for the cloud phase retrieved from each satellite. When comparing the COT from both satellites directly, the values from HIMAWARI tended to be larger than the data from GK-2A. A comparison of the UV-A radiation shows that the observed values are seemingly larger than the satellite results,indicating that both satellites may overestimate the cloud optical depth. Additionally, when both satellites were estimated to have the same cloud phase, HIMAWARI showed better parameters for RMSE and MAE, whereas GK-2A was better when GK-2A and HIMAWARI had different cloud phase estimates. By comparing the freezing level from the vertical profile and the cloud top height from each satellite, the actual cloud phase was estimated, which showed that GK-2A had better performance in estimating cloud phases.