• Title/Summary/Keyword: Radiation medium

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Performance Evaluation of a Fiber-Optic Cerenkov Radiation Sensor System Using a Simulated Spent Fuel Assembly (사용후핵연료 집합체 모사장치를 이용한 광섬유 체렌코프 방사선 센서 시스템의 성능평가)

  • Shin, Sang Hun;Yoo, Wook Jae;Jang, Kyoung Won;Cho, Seunghyun;Park, Byung Gi;Lee, Bongsoo
    • Journal of Sensor Science and Technology
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    • v.23 no.4
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    • pp.245-250
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    • 2014
  • 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.

Radiation Shielding to Minimize Image Information Loss (영상 정보 손실을 최소화하는 방사선 차폐체 연구)

  • Su-han Jang;Sang-Hyeun Park;Myeong-Sik Ju
    • Journal of the Korean Society of Radiology
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    • v.17 no.3
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    • pp.449-457
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    • 2023
  • Shielding for reducing exposure dose can make the diagnosis limited. The purpose of this study is to increase the efficiency of radiation protection and minimize the loss of image information by producing the shielding made of the water and the contrast medium which has different proportion and finding out the ideal proportion of them. Each shielding materials were made of water and water-soluble iodine contrast medium with the different proportion. The attenuation rate of absorbed dose was evaluated by the shielding materials in the plastic contents for measuring the efficiency of the radiation protection. As a result, the higher ratio of the contrast medium, the more efficient it is for radiation attenuation. The anatomical structure was observed most properly in case of the solution with 20 ml of the contrast medium and most difficultly in case of more than 60 ml of the contrast medium. In case of the signal intensity between skeleton and gas, the difference of average value had a significant as p < 0.001. Shielding with contrast medium attenuates less than the conventional shielding but in the examination for the sensitive part to radiation, it can be used to minimize the loss of the image information and reduce the exposure dose.

A Study of Image Quality and Exposed Dose by Field Size Changing on CBCT (CBCT 촬영 시 조사야 조절에 따른 영상의 최적화 및 피폭선량에 관한 고찰)

  • Bang, Seung Jae;Kim, Young Yeon;Jeong, Il Seon;Kim, Jeong Soo;Kim, Young Gon
    • The Journal of Korean Society for Radiation Therapy
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    • v.25 no.2
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    • pp.175-180
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    • 2013
  • Purpose: Modern radiation therapy technique such as IGRT has become a routine clinical practice on LINAC for decrease patient's set-up error. CBCT can be used to adjust patient set-up error and treat patient more accurately. The Purpose of this study is to evaluate field size of CBCT for improving Image quality and suggest reference date of CBCT field size. Materials and Methods: Image date were acquired using KV CBCT and Catphan phantom (Half fan and full fan mode were scanned from 2 ~16 cm, at intervals of 2 cm). Field size were categorized by Small field size (2 cm, 4 cm), Medium field size (8 cm, 10 cm), Large field size (more than 14 cm) and evaluate. To estimated the CTDi using CTDi phantom and Ion chamber. Results: CT number linearity of Small and Large field size are greater than Medium field size. Spatial resolution are not significantly different without Small field size. But half fan mode is more different than full fan mode. In full fan, except Medium field size, all field size exceed recommendation for HU uniformity. But half pan has stability for all field except Small field size. CTDi makes radical sign function graph in Medium field size. Conclusion: The worst result was given by Small field size for Image quality and practically. Medium field size can be useful to prevent patient from radiation exposure and give better Image quality. So this study recommends that Medium field size (8~10 cm) is more suitable for CBCT.

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Study on Stable Fly Eradication by :Sterile-Male Technique. 1) Mass Rearing of the Stable Fly. Stemoxys calcitrans L. (웅성불임기술을 이용한 쇠파리 구제에 관한 연구 1) 쇠파리의 인공대량사육에 관하여)

  • Chung K. H.;Ryu J.;Kim Y. R.;Kwon S. H.;Park J. D.;Kang T. S.
    • Korean journal of applied entomology
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    • v.12 no.1
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    • pp.41-46
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    • 1973
  • 1) The optimum temperature for mass rearing of stable fly was $26^{\circ}C$ centigrade. Number of days required for stage of development at $26^{\circ}C$ were 6.8 days for larval stage, 5.3 days for pupla stage, 10.4 days for preovipositionla stage, and 30 days for adult stage respectively. 3) The pupation rate, emergence rate and sex ratio were $80.7\%,\;84.3\%$ and 1 : 1, respectively. 3) The average weight of pupae was 14.5mg, and the standard medium showed better result in larvae rearing than wheat bran medium. 4) The optimum number of eggs for inoculation on 125gr medium was approximately 310. 5) Optimum size of resting place was determined as $2inch^2/adult$ when it reared in a rectangular cage.

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Effects of Radiation on Conjugate Natural Convection from a Vertical Plate Fin (수직 평판휜으로부터의 복합자연대류에 미치는 복사효과)

  • 김경훈;김세웅
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.2
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    • pp.382-390
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    • 1992
  • The problem of natural convection from a vertical fin is solved by coupling the thermal diffusion equation in the fin to the constitutive equations of the ambient medium involving the radiation of the medium. The analysis is accomplished by employing an integral method. The governing equations for the problem are solved by shooting method based on the Runge-Kutta Scheme at Pr= 0.7. For the range of values of the fin parameter and the radiation-conduction parameter in the analysis, the numerical results show that the radiation effects play an important role in the heat transfer and enhance the heat transfer.

SORET AND ELECTROMAGNETIC RADIATION EFFECT OF MHD MICRO POLAR FLUID PAST A POROUS MEDIUM IN THE PRESENCE OF CHEMICAL REACTION

  • SHEEBA JULIET S.;VIDHYA, M.
    • Journal of applied mathematics & informatics
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    • v.41 no.5
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    • pp.1085-1102
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    • 2023
  • In this study the magneto hydrodynamic (MHD) micro polar fluid flow of a viscous incompressible fluid past a porous medium in the presence of chemical reaction is considered. This work is devoted to investigate the Soret effect and Electromagnetic radiation effect and analyze analytically. In the energy equation the applied magnetic field strength and in the concentration equation the Soret effect are incorporated. The basic PDE (partial differential equations) are reduced to ODE (ordinary differential equations) using non dimensional variables. Then the analytical solution of the dimensionless equations are found using perturbation technique. The features of the fluid flow parameters are analyzed, discussed and explained graphically. The graphical solutions are found using MATLAB R2019b. Skin friction coefficient at the wall, Couple stress coefficient at the plate and the local surface heat flux are also thoroughly examined. Overall, this study sheds light on the complex interplay between physical parameters in the behavior of MHD micro-polar fluid past a porous medium in the presence of chemical reaction.

The Cell Cycle Dependence and Radiation-induced Apoptosis in SCK Mammary Adenocarcinoma Cell Line (SCK선암 세포주에서 방사선에 의한 Apoptosis와 세포 주기)

  • Lee Hyung Sik;Park Hong Kyu;Hur Won Joo;Seo Su Yeong;Lee Sang Hwa;Jung Min Ho;Park Heon Joo;Song Chang Won
    • Radiation Oncology Journal
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    • v.16 no.2
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    • pp.91-98
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    • 1998
  • Purpose : The relationship between environmental PH on the radiation induced-apoptosis in SCK mammary adenocarcinoma cells and cell cycle dependence was investigated. Material and Methods : Mammary adenocarcinoma cells of A/J mice(SCK cells) in exponential growth phase were irradiated with a $l37^Cs$ irradiator at room temperature. The cells were irradiated 1 hour after the media was replaced with fresh media at a different pHs. After incubation at $37^{\circ}C$ for 0-48 h, the extent of apoptosis was determined using agarose gel electrophoresis and flow cytometry. The progression of cells through the cell cycle after irradiation in different pHs was also determined with flow cytometry. Bssults : The induction of apoptosis by irradiation in pH 6.6 medium was markedly less than that in pH 7.5 medium. When the cells were irradiated and maintained in pH 7.5 medium, the percentage of cells in $G_2/M$ phase rapidly increased to about $70\%$ at 12 h after an exposure to 120y and returned to control level by 36 h. The percentage of cells in G1 phase decreased as the percentage of cells in $G_2/M$ increased. On the other hand, in pH 6.6 medium the percentage of cells in G2/M phases gradually increased to about $45\%$ at 24 h after 12Gy irradiation and then slowly recessed and consequently, as much as $30-35\%$ of the cells were still in the Ga/M phase 48 h after irradiation. The percentage of cells in G1 phase then increased as the Ga/M arrest began to recede. The radiation-induced Ga/M arrest in PH 0.0 medium lasted markedly longer than that in pH 7.5 medium. Conclusion : Radiation-induced apoptosis in SCK tumor cells are reversely suppressed in an acidic environment. Radiation-induced Ga/M arrest is prolonged in an acidic environment indicating that the suppression of radiation-induced apoptosis and prolongation of radiation-induced Ga/M arrest in an acidic environment are related.

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The Premixed Flame in a Radiatively Active Porous Medium (복사열전달을 동반하는 다공성 매질내의 예혼합 화염)

  • 김정수;백승욱
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.2
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    • pp.265-270
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    • 1989
  • The present study considers the thermal structure variation in a porous medium caused by changing the most important radiative property of porous medium, absorption coefficient, as well as altering the physical dimension of porous medium and the equivalence ratio of premixed gas mixture. The radiation model was introduced as an unsteady differential form using the two-flux gray radiation model. The role of the conductive heat transfer through both gas phase and porous medium was found to be almost insignificant compared with that of the radiative heat transfer. The reaction zone shifted upstream and the flame thickness decreased as either the geometrical length of porous medium increased or the absorption coefficient decreased.

Influence of Intravenous Contrast Medium on Dose Calculation Using CT in Treatment Planning for Oesophageal Cancer

  • Li, Hong-Sheng;Chen, Jin-Hu;Zhang, Wei;Shang, Dong-Ping;Li, Bao-Sheng;Sun, Tao;Lin, Xiu-Tong;Yin, Yong
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.3
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    • pp.1609-1614
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    • 2013
  • Objective: To evaluate the effect of intravenous contrast on dose calculation in radiation treatment planning for oesophageal cancer. Methods: A total of 22 intravein-contrasted patients with oesophageal cancer were included. The Hounsfield unit (HU) value of the enhanced blood stream in thoracic great vessels and heart was overridden with 45 HU to simulate the non-contrast CT image, and 145 HU, 245 HU, 345 HU, and 445 HU to model the different contrast-enhanced scenarios. 1000 HU and -1000 HU were used to evaluate two non-physiologic extreme scenarios. Variation in dose distribution of the different scenarios was calculated to quantify the effect of contrast enhancement. Results: In the contrast-enhanced scenarios, the mean variation in dose for planning target volume (PTV) was less than 1.0%, and those for the total lung and spinal cord were less than 0.5%. When the HU value of the blood stream exceeded 245 the average variation exceeded 1.0% for the heart V40. In the non-physiologic extreme scenarios, the dose variation of PTV was less than 1.0%, while the dose calculations of the organs at risk were greater than 2.0%. Conclusions: The use of contrast agent does not significantly influence dose calculation of PTV, lung and spinal cord. However, it does have influence on dose accuracy for heart.

Radiation-Laminar Free Convection in a Square Duct with Specular Reflection by Absorbing-Emitting Medium

  • Byun, Ki-Hong;Im, Moon-Hyuk
    • Journal of Mechanical Science and Technology
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    • v.16 no.10
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    • pp.1346-1354
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    • 2002
  • The purpose of this work is to study the effects of specularly reflecting wall under the combined radiative and laminar free convective heat transfer in an infinite square duct. An absorbing and emitting gray medium is enclosed by the opaque and diffusely emitting walls. The walls may reflect diffusely or specularly. Boussinesq approximation is used for the buoyancy term. The radiative heat transfer is evaluated using the direct discrete ordinates method. The parameters under considerations are Rayleigh number, conduction to radiation parameter, optical thickness, wall emissivity and reflection mode. The differences caused by the reflection mode on the stream line, and temperature distribution and wall heat fluxes are studied. Some differences are observed for the categories mentioned above if the order of the conduction to radiation parameter is less than order of 10$\^$-3/ fer the range of Rayleigh number studied. The differences at the side wall heat flux distributions are observed as long as the medium is optically thin. As the top wall emissivity decreases, the differences between these two modes are increased. As the optical thickness decreases at the fixed wall emissivity, the differences also increase. The difference of the streamlines or the temperature contours is not as distinct as the side wall heat flux distributions. The specular reflection may alter the fluid motion.