• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.863-870
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• 2022

DLG (Dosimetric Leaf Gap) and transmission factor are important parameters of MLC modeling in treatment planning system. In this study, DLG and transmission factor of HD-MLC were measured using detector with different measuring volumes, and the accuracy of the treatment plans was evaluated according to the DLG values. DLG was measured using the dynamic sweeping gap method with Semiflux3D and MicroDiamond detectors. Then, 10 radiation treatment plans were generated to optimize the DLG value and compared with the measurement results. Photon energies 6, 8, 10 MV, the DLG measured by Semiflux3D were 0.76, 0.83, and 0.85 mm, and DLG measured by MicroDiamond were 0.78, 0.86, and 0.9 mm. All plans were measured by portal dosimetry and analyzed using Gamma Evaluation. In the 6 MV photon beams, the average gamma passing rate were 94.3% and 98.4% for DLG 0.78 mm and 1.15 mm. In the 10 MV photon beam, the average gamma passing rate were 91.2% and 97.6% for DLG 0.9 mm and 1.25 mm. HD-MLC needs accurate modeling in the treatment planning system. DLG could be used measured data using small volume detector. However, for better radiation therapy, DLG should be optimized at the commissioning stage of LINAC.

• Journal of Radiation Industry
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• v.6 no.2
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• pp.139-145
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• 2012

Gold nanoparticles (GNPs) have led to the development of a new field in the diagnosis and treatment of diseases such as cancer. An efficient synthesis of gold nanoparticles within the range of 8~57 nm was established by ${\gamma}-ray$ irradiation. The good point of a radiation-based method is the production of gold nanoparticles with a higher concentration and narrower size distribution compared with conventional methods. The size of gold nanoparticles was controlled using two methods. : (i) varying the ${\gamma}-ray$ irradiation dose of 10 to 25 kGy and (ii) varying the concentration of $HAuCl_4$ solution from 4 to 40 mM. In addition, the GNPs were radiolabeled using $[^{125}I]NaI$ in a simple and fast manner with high yields. The produced gold nanoparticles were characterized using a transmission electron microscopy (TEM), a UV-visible spectrophotometer, and a radio-TLC imaging scanner. From these results, these radiolabeled GNPs can be applicable for a radioisotope tag of biomolecules.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.278-284
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• 2023

The synthetic B₂O₃-As₂O₃ glass ceramic are prepared to investigate the physical properties and the radiation shielding capabilities with the variation of concentration of the As₂O₃ with 10, 20, 30, and 40%, respectively. XRD analyses are performed on the fabricated glass-ceramic and depicted the improvement of crystallinity by adding As₂O₃. The radiation shielding properties are studied for the B₂O₃-As₂O₃ glass ceramic. The values of linear attenuation coefficient (LAC) are varied with the variation of incident photon gamma energy (23.1-103 keV). The LAC values enhanced from 12.19 cm^-1-37.75 cm^-1 by raising the As₂O₃ concentration from 10 to 40 mol% at low gamma energy (23.1 keV) for BAs10 and BAs40, respectively. Among the shielding parameters, the half-value layer, transmission factor, and radiation protection efficiency are estimated. Furthermore, the fabricated samples of glass ceramic have low manufacturing costs and good shielding features compared to the previous work. It can be concluded the B₂O₃-As₂O₃ glass ceramic is appropriate to apply in X-ray or low-energy gamma-ray shielding applications.

• The Journal of the Acoustical Society of Korea
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• v.34 no.5
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• pp.335-342
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• 2015

Phononic crystals are composite materials consisting of a periodic arrangement of scattering inclusions in a host material. One of the most important properties of phononic crystals is the existence of band gaps, i.e., ranges of frequencies at which acoustic waves cannot propagate through the structure. The present study aims to investigate theoretically and experimentally the acoustic band structures in two-dimensional (2D) phononic crystals consisting of periodic square arrays of stainless steel solid cylinders with a diameter of 1 mm and a lattice constant of 1.5 mm in water. The theoretical dispersion relation that depicts the relationship between the frequency and the wave vector was calculated along the ${\Gamma}X$ direction of the first Brillouin zone using the finite element method to predict the band structures in the 2D phononic crystals. The transmission and the reflection coefficients were measured in the 2D phononic crystals with 1, 3, 5, 7, and 9 layers of stainless steel cylinders stacked in the perpendicular direction to propagation at normal incidence. The theoretical dispersion relation exhibited five band gaps at frequencies below 2 MHz, the first gap appearing around a frequency of 0.5 MHz. The location and the width of the band gaps experimentally observed in the transmission and the reflection coefficients appeared to coincide well with those determined from the theoretical dispersion relation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.6
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• pp.15-23
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• 2011

Driving directly in front of the driver of a vehicle driving in front of the vehicle and it is commonly known is affected. Responding to the car in front of the driver and the vehicle in front, and these follow the model is known as Three-Car-Following Model. Platoon vehicles to follow behind the driver's visibility is affected by the a tinted vehicle, and Parameters of the model is estimated to be affected also. In this study, in Three-Car-Followng Model parameters were estimated. and the parameter values differ about whether and how analysis was performed by the level of Visible Light Transmission Percentage. RTK GPS receiving data through field experiment analyzed based on sensitivity of three car by Visible Light Transmission Percentage and ${\gamma}$. And With statistical verification of driving directly in front of the driver in front of the vehicle and that the moving vehicle is influenced also confirmed. Also Visible Light Transmission Percentage is lowered, the vehicle in front of the driver's behavior showed sensitive reactions. In the further need to research for influence analysis of traffic flow capacity by the level of VLT.

• Journal of Veterinary Science
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• v.23 no.3
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• pp.37.1-37.8
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• 2022

Background: Avian pathogenic Escherichia coli (APEC) causes colibacillosis, resulting in significant economic losses in the poultry industry. Objectives: In this study, the molecular characteristics of two extended-spectrum beta-lactamase (ESBL)-producing APEC isolates were compared with previously reported ESBL-producing E. coli isolates. Methods: The molecular characteristics of E. coli isolates and the genetic environments of the ESBL genes were investigated using whole genome sequencing. Results: The two ESBL-producing APEC were classified into the phylogenetic groups C and B1 and ST410 and ST162, respectively. Moreover, the ESBL genes of the two isolates were harbored in different Inc plasmids. The EC1809182 strain, harboring the bla_CTX-M-55 gene on the plasmid, exhibited extensive homology to IncFIB (98.4%) and IncFIC(FII) (95.8%). The EC1809191 strain, harboring the bla_CTX-M-1 gene, was homologous to IncI1-I (Gamma) (99.3%). All chromosomes carried the multidrug transporter, mdf(A) gene. Mobile genetic elements, adjacent to CTX-M genes, facilitated the dissemination of genes in the two isolates, analogous to other ESBL-producing E. coli isolates. Conclusions: This study clarifies the transmission dynamics of CTX-M genes and supports strengthened surveillance to prevent the transmission of the antimicrobial-resistant genes to humans via the food chain.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.499-508
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• 2000

The purposes of this study were to evaluate the validity of 2 kinds of digital radiography techniques in evaluating the radiopacity comparison of restorative materials and to determine the relative radiopacities of several kinds of compomer and flow able resin using these techniques. After taking radiographs of an aluminum step wedge, con-elation of optical density calibration curves were evaluated between conventional radiography with transmission densitometer and CD-Dent digital radiography (storage phosphor system) and between conventional one and RVG$^{(R)}$ digital radiography (CCD system). Compomers such as Dyract$^{(R)}$ AP, Compoglass$^{(R)}$, and Dyract flow$^{(R)}$, and flowable resins such as Ultraseal-XT$^{(R)}$ plus$^{TM}$, Revolution$^{TM}$, Aeliteflo$^{TM}$ and Tetric-flow$^{(R)}$ were used. Five specimens of 5mm in diameter and 2 mm thick were fabricated with each material. Radiopacities of the materials were measured using the above radiographic techniques and compared. The results were as follows: 1. When the optical density calibration curves were compared, conventional radiography and both CD-Dent and RVG$^{(R)}$ digital radiographies showed very high inverse correlations (${\gamma}$=-0.95, ${\gamma}$=-0.98 ; p<0.05). 2. All the tested restorative materials showed levels of radiopacity the same as or greater than that of dentin (p<0.05), Radiopacities of Dyract$^{(R)}$ AP, Compoglass$^{(R)}$, and Tetric flow$^{(R)}$ were greater than those of Revolution$^{TM}$, Aeliteflo$^{TM}$, or dentin (p<0.05). 3. Radiopacities of Dyract$^{(R)}$ AP, Compoglass$^{(R)}$, and Tetric flow$^{(R)}$ were shown to be greater than that of enamel when conventional radiography and CD-Dent digital radiography were used (p<0.05). Radiopacity of Dyract flow$^{(R)}$ was shown to be greater than that of Enamel when conventional radiography was used (p<0.05).

• Progress in Medical Physics
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• v.9 no.3
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• pp.155-162
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• 1998

Ho-l66 was produced by neutron reaction in a reactor at the Korea Atomic Energy Institute (Taejon, Korea). Ho-l66 emits a high energy beta particles with a maximum energy of 1.85 MeV and small proportion of gamma rays (80 keV). Therefore, the radiation absorbed dose estimation could be based on the in-vivo quantification of the activity in tumors from the gamma camera images. Approximately 1 mCi of Ho-l66 in solution was mixed into the flood phantom and planar scintigraphic images were acquired with and without patient interposed between the phantom and scintillation camera. Transmission factor over an area of interest was calculated from the ratio of counts in selected regions of the two images described above. A dual-head gamma camera(Multispect2, Siemens, Hoffman Estates, IL, USA) equipped with medium energy collimators was utilized for imaging(80 keV${\pm}$10%). Fifty-nine year old female patient with hepatoma was enrolled into the therapeutic protocol after the informed consent obtained. Thirty millicuries(110MBq) of Ho-166-CHICO was injected into the right hepatic arterial branch supplying hepatoma. When the injection was completed, anterior and posterior scintigraphic views of the chest and pelvic regions were obtained for 3 successive days. Regions of interest (ROIs) were drawn over the organs in both the anterior and posterior views. The activity in those ROIs was estimated from geometric mean, calibration factor and transmission factors. Absorbed dose was calculated using the Marinelli formula and Medical Internal Radiation Dose (MIRD) schema. Tumor dose of the patient treated with 1110 MBq(30 mCi) Ho-l66 was calculated to be 179.7 Gy. Dose distribution to normal liver, spleen, lung and bone was 9.1, 10.3, 3.9, 5.0 % of the tumor dose respectively. In conclusion, tumor dose and absorbed dose to surrounding structures were calculated by daily external imaging after the Ho-l66 therapy for hepatoma. In order to limit the thresholding dose to each surrounding organ, absorbed dose calculation provides useful information.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.1
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• pp.67-72
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• 2012

In this paper, we present an image enhancement method for atmospherically degraded images using atmospheric light and transmission based on color analysis. We first generate a normalized image using maximum value of each RGB color channel. Then, each atmospheric light is estimated from RGB color channel respectively by calculating reflectance of an image. We also, generate a transmission using gamma coefficients from the Y channel of the image. We can significantly enhance the visibility of an image by using the estimated atmospheric light and the transmission. The proposed algorithm can remove atmospheric degradation components better than existing techniques because the color prevents color distortion which is common problem of existing techniques. Experimental results demonstrate that the proposed algorithm can improve visibility be removing fog, smoke, and dust.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.564-567
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• 2012

Optical fibers are going to be used for telecommunication, image fibers, sensors under irradiation in nuclear power plants and various irradiation facilities. Especially, Temperature detection sensors using Raman light scattering, temperature or strain sensors using fiber gratings, magnet-optical sensors using photo-magnetic effect, are already commercialized. However, When fibers are exposed to ionizing radiation, color centers are formed in fibers which reduces their light transmission, and it is limited in applying under radiation environments. In this study, $Co^{60}$ gamma-ray induced optical attenuation on Ge-doped single mode(SM) fiber has been measured. Gamma-ray is irradiated for 4hours at the dose rate of 0.5kGy/hr, 2kGy/hr, 8kGy/hr. Consequently, gamma-ray induced loss based on radiation effects in Ge-doped SM fiber occur precisely. Furthermore, dose rate effect that the higher dose rate in the same total dose, the more increase loss of optical fiber and annealing effect that the higher the loss after irradiation, the more increase the recovery rate of the loss are observed in the fiber. This results plan to make use of bases in the study of the radiation-hardened optical fiber.