• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.329-336
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• 2014

Purpose : To evaluate the dose on a contralateral breast and the usefulness of shielding according to the distance between the contralateral breast and the side of the beam by breast size when patients who got breast implant receive radiation therapy. Materials and Methods : We equipped 200 cc, 300 cc, 400 cc, and 500 cc breast model on the human phantom (Rando-phantom), acquired CT images (philips 16channel, Netherlands) and established the radiation treatment plan, 180 cGy per day on the left breast (EclipseTM ver10.0.42, Varian Medical Systems, USA) by size. We set up each points, A, B, C, and D on the right(contralateral) breast model for measurement by size and by the distance from the beam and attached MOSFET at each points. The 6 MV, 10 MV and 15 MV X-ray were irradiated to the left(target) breast model and we measured exposure dose of contralateral breast model using MOSFET. Also, at the same condition, we acquired the dose value after shielding using only Pb 2 mm and bolus 3 mm under the Pb 2 mm together. Results : As the breast model is bigger from 200 cc to 500 cc, The surface of the contralateral breast is closer to the beam. As a result, from 200 cc to 500 cc, on 180 cGy basis, the measurement value of the scattered ray inclined by 3.22 ~ 4.17% at A point, 4.06 ~ 6.22% at B point, 0.4~0.5% at C point, and was under 0.4% at D point. As the X-ray energy is higher, from 6 MV to 15 MV, on 180 cGy basis, the measurement value of the scattered ray inclined by 4.06~5% at A point, 2.85~4.94% at B point, 0.74~1.65% at C point, and was under 0.4% at D point. As using Pb 2 mm for shield, scattered ray declined by average 9.74% at A and B point, 2.8% at C point, and is under 1% at D point. As using Pb 2 mm and bolus together for shield, scattered ray declined by average 9.76% at A and B point, 2.2% at C point, and is under 1% at D point. Conclusion : Commonly, in case of patients who got breast implant, there is a distance difference by breast size between the contralateral breast and the side of beam. As the distance is closer to the beam, the scattered ray inclined. At the same size of the breast, as the X-ray energy is higher, the exposure dose by scattered ray tends to incline. As a result, as low as possible energy wihtin the plan dose is good for reducing the exposure dose.

• Progress in Medical Physics
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• v.26 no.4
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• pp.193-200
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• 2015

The aim of this study is to present commissioning results of the ViewRay system. We verified safety functions of the ViewRay system. For imaging system, we acquired signal to noise ratio (SNR) and image uniformity. In addition, we checked spatial integrity of the image. Couch movement accuracy and coincidence of isocenters (radiation therapy system, imaging system and virtual isocneter) was verified. Accuracy of MLC positioing was checked. We performed reference dosimetry according to American Association of Physicists in Medicine (AAPM) Task Group 51 (TG-51) in water phantom for head 1 and 3. The deviations between measurements and calculation of percent depth dose (PDD) and output factor were evaluated. Finally, we performed gamma evaluations with a total of 8 IMRT plans as an end-to-end (E2E) test of the system. Every safety system of ViewRay operated properly. The values of SNR and Uniformity met the tolerance level. Every point within 10 cm and 17.5 cm radii about the isocenter showed deviations less than 1 mm and 2 mm, respectively. The average couch movement errors in transverse (x), longitudinal (y) and vertical (z) directions were 0.2 mm, 0.1 mm and 0.2 mm, respectively. The deviations between radiation isocenter and virtual isocenter in x, y and z directions were 0 mm, 0 mm and 0.3 mm, respectively. Those between virtual isocenter and imaging isocenter were 0.6 mm, 0.5 mm and 0.2 mm, respectively. The average MLC positioning errors were less than 0.6 mm. The deviations of output, PDDs between mesured vs. BJR supplement 25, PDDs between measured and calculated and output factors of each head were less than 0.5%, 1%, 1% and 2%, respectively. For E2E test, average gamma passing rate with 3%/3 mm criterion was $99.9%{\pm}0.1%$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.291-303
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• 2020

The Kori-Unit 1 nuclear power plant, which is scheduled to be decommissioned after permanent shutdown, is expected to generate large amounts of various types of radioactive waste during the decommissioning process. Among these, nuclear reactors and internal structures have high levels of radioactivity and the dismantled structure must have the proper size and weight on the primary side. During decommissioning, it is important to prepare an appropriate and efficient disposal method through analysis of the disposal status and the legal restrictions on wastes generated from the reactors and internal structures. Nuclear reactors and internal structures generate radioactive wastes of various levels, such as medium, very low, and clearance. A radiation evaluation indicates that wastes in the clearance level are generated in the reactor head and upper head insulation. In this study, a clearance waste safety evaluation was conducted using the RESRAD-RECYCLE code, which is a safety evaluation code, based on the activation evaluation results for the clearance level wastes. The clearance scenario for the target radioactive waste was selected and the maximum individual and collective exposure doses at the time of clearance were calculated to determine whether the clearance criteria limit prescribed by the Nuclear Safety Act was satisfied. The evaluation results indicated that the doses were significantly low, and the clearance criteria were satisfied. Based on the safety assessment results, an appropriate metal recycle and disposal method were suggested for clearance, which are the subject of the deregulation of internal structures of nuclear power plant.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.21-29
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• 2005

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality in February, 1995. Recently, ten years after the initial operation of the HANARO, one of the two primary cooling pumps was decontaminated for overhaul maintenance in 2004. Before decontamination exposure doserate and surface contamination level of primary cooling pump measured at 4 points. After final decontamination exposure doserate and surface contamination level of primary cooling pump remeasured by same method done before. It is easy to decontaminate the out side exposed surfaces of the pump, but it is difficult to approach the inside surface due to double volute installed in the casing. Therefore, a new decontamination facility has been developed to solve this problem. A concentrated de-contaminant (DX-300) is rotated in the closed pump casing by the impeller actuated by a temporary motor. Nuclide particles are removed by the emulsification effect of the de-contaminant and the surface contaminants are chemically removed from the pump by the corrosion and dissolution effect. The inside surfaces of the primary cooling pump have been decontaminated by using the facility. As results, the contamination level of the inside surfaces was maintained below the surface contamination limit.

• Food Science and Preservation
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• v.20 no.1
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• pp.97-103
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• 2013

The effects of gamma irradiation at medium dose levels on commercial starches (corn starch/CS, sweet potato starch/SS, and potato starch/PS) were investigated in terms of its color and lipid oxidation. The CS, SS, and PS samples were irradiated at 0, 1.5, 3, 4.5 and 6 kGy by a Co-60 gamma irradiator and used for measuring Hunter's colors and TBA value. Irradiation doses applied did not cause apparent changes in Hunter color parameters between the control and irradiated groups. But, the decrease in lightness (L value) for CS and the increase in both redness (a value) for SS and yellowness (b value) for PS were observed, respectively, thereby resulting in slight increase in overall color difference (${\Delta}E$) upon irradiation. Browning intensity observed with the naked eye for gelatinized starches by irradiation doses was also gradually increased along with irradiation dose, which was more remarkable in SS. The thiobarbituric acid (TBA) values of samples showed a dose-dependant increase with ${\geq}0.9964$ of $R^2$ (p<0.05).

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.755-762
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• 2023

The reliability of measuring instruments is essential in measuring cosmic radiation. To demonstrate this importance, this study measured and compared the amount of cosmic radiation using Liulin and TEPC, operated in South Korea, on a flight between Incheon, South Korea and LA, the US. In addition, since prior analysis based on a prediction program is necessary in advance to check the dose of cosmic radiation, this study utilized KREAM developed in Korea and the CARI-6M developed by the FAA to acquire the predicted value. As a result of the verification, the reliability of the two devices falls within the acceptable level of 20%, proving the reliability. Moreover, the differences between the values acquired by each prediction program were only subtle. Nevertheless, the analysis demonstrated that the prediction value obtained by the programs and the measured value had significant differences. Therefore, additional correction of the discrepancies or continuous research for such is required to match the predicted values are similar to the actual measured values.

• The Journal of Engineering Geology
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• v.15 no.2 s.42
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• pp.213-227
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• 2005

This study aims to assess the problems with investigation method and to suggest the complementary solutions by comparing the predicted data from surface investigation with the outcome data from underground cavern. In the study area, one(NE-1) of 6 fracture zones predicted during the surface investigation was only confirmed in underground caverns. Therefore, it is necessary to improve the confidence level for prediction. In this study, the fracture classification criteria was quantitatively suggested on the basis of the BHTV images of NE-1 fracture zone. The major orientation of background fractures in rock mass was changed at the depth of the storage cavern, the length and intensity were decreased. These characteristics result in the deviation of predieted predicted fracture properties and generate the investigation bias depending on the bore hole directions and investigated scales. The evaluation of hydraulic connectivity in the surface investigation stage needs to be analyze by the groundwater pressures and hydrochemical properties from the monitoring bore hole(s) equipped with a double completion or multi-packer system during the test bore hole is pumping or injecting. The hydraulic conductivities in geometric mean measured in the underground caverns are 2-3 times lower than those from the surface and furthermore the horizontal hydraulic conductivity in geometric mean is six times lower than the vertical one. To improve confidence level of the hydraulic conductivity, the orientation of test hole should be considered during the analysis of the hydraulic conductivity and the methodology of hydro-testing and interpretation should be based on the characteristics of rock mass and investigation purposes.

• Journal of Chest Surgery
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• v.38 no.7 s.252
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• pp.489-495
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• 2005

In the surgical treatment of aortic dissection, aortic arch replacement under total circulatory arrest is often performed after careful inspection to determine the severity of disease progression. Under circulatory arrest, antegrade or retrograde cerebral perfusion is required for brain protection. Recently, antegrade cerebral perfusion has been used more, because of the limitation of retrograde cerebral perfusion. This study is to compare these two methods especially in the respect to neurological complications. Material and Method: Forty patients with aortic dissection involving aortic arch from May 2000 to May 2004 were enrolled in this study, and the methods of operation, clinical recovery, and neurological complications were retrospectively reviewed. Result: In the ACP (antegrade cerebral perfusion) group, axillary artery cannulation was performed in 10 out of 15 cases. In the RCP (retrograde cerebral perfusion) group, femoral artery Cannulation was performed in 24 out of 25 cases. The average esophageal and rectal temperature under total circulatory arrest was $17.2^{\circ}C\;and\;22.8^{\circ}C$ in the group A, and $16.0^{\circ}C\;and\;19.7^{\circ}C$ in the group B, respectively. Higher temperature in the ACP group may have brought the shorter operation and cardiopulmonary bypass time. However, the length of period for postoperative clinical recovery and admission duration did not show any statistically significant differences. Eleven out of the total 15 cases in the ACP group and thirteen out of the total 25 cases in the RCP group showed neurological complication but did not show statistically significant difference. In each group, there were 5 cases with permanent neurological complications. All 5 cases in the ACP group showed some improvements that enabled routine exercise. However all 5 cases in RCP group did not show significant improvements. Conclusion: The Antegrade, cerebral perfusion, which maintains orthordromic circulation, brings moderate degree of hypothermia and, therefore, shortens the operation time and cardiopulmonary bypass time. We concluded that Antegrade cerebral perfusion is safe and can be used widely under total circulatory arrest.

• Radiation Oncology Journal
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• v.13 no.4
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• pp.331-338
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• 1995

Purpose : To evaluate our clinical experience with the combination of teletherapy and intraluminal brachytherapy in patients with unresectable or inoperable esophageal cancers. Materials and Methods : From Nov 1989 to Mar 1993, twenty patients with esophageal cancer were treated with radical radiotherapy and intraluminal brachytherapy at Yonsei Cancer Center. All patients had squamous histolgy and stage distribution was as follows: stage II, 4($20{\%}$)patients; III, 15 ($75{\%}$)patients; IV, 1($5{\%}$)patients. A dose of S-12Gy/1-3weeks with intraluminal brachytherapy (3-5Gy/fraction) to 5mm from the outside of the esophageal tube using high dose rate Iridium-192 remotely afterloading brachytherapy machine was given 2 weeks after a total dose of 59-64Gy with external radiotherapy. Induction chemotherapy using cisplatin and 5-FU was performed in 13 patients with median 3 cycles(1-6 cycles), Response rate, local control rate, survival and complications were analysed retrospectively. Results : Two-year overall survival rate and median survival were $15.8{\%}$ and 13.5 months. Response rates were as follows complete remission(CR) 5($25{\%}$): partial remission a(PRa) 7($35{\%}$): partial remission b(PRb) 7($35{\%}$), no response(NR) 1($5{\%}$). Patterns of failure were as follows; local failure 13($65{\%}$), local and distant failure 3($15{\%}$), distant failure 0($0{\%}$). Ultimate local control rate was $20{\%}$. Treatment related complications included esophageal ulcer in two patients and esophageal stricture in one. Conclusion : Though poor local conrol rate, median survival was improved as compared with previous results of radiation therapy alone(8months) and chemoradiation combined treatment(11 months) in Yonsei Cancer Center High-dose-rate intraluminal brachytherapy following external irradiation is an effective treatment modality with acceptable toxicity in esophageal cancer.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.145-151
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• 2013

Purpose: In this study, we analyzed how the dose change by field size effects on atomic number of shielding materials while using 6 MeV election beam. Materials and Methods: The parallel plate chamber is mounted in $25{\times}25cm^2$ the phantom such that the entrance window of the detector is flush with the phantom surface. phantom was covered laterally with aluminum, copper and lead which thickness have 5% of allowable transmission and then the doses were measured in field size $6{\times}6$, $10{\times}10$ and $20{\times}20cm^2$ respectively. 100 cGy was irradiated using 6 MeV electron beam and SSD (Source Surface Distance) was 100 cm with $10{\times}10cm^2$ field size. To calculate the photon flux, electron flux and Energy deposition produced after pass materals respectively, MCNPX code was used. Results: The results according to the various shielding materials which have 5% of allowable transmission are as in the following. Thickness change rate with field size of $6{\times}6cm^2$ and $20{\times}20cm^2$ that compared to the field size of $10{\times}10cm^2$ found to be +0.06% and -0.06% with aluminum, +0.13% and -0.1% with copper, -1.53% and +1.92% with lead respectively. Compare to the field size $10{\times}10cm^2$, energy deposition for $6{\times}6cm^2$ and $20{\times}20cm^2$ had -4.3% and +4.85% respectively without shielding material. With aluminum it had -0.87% and +6.93% respectively and with lead it had -4.16% and +5.57% respectively. When it comes to photon flux with $6{\times}6cm^2$ and $20{\times}20cm^2$ of field sizes the chance -8.95% and +15.92% without shielding material respectively, with aluminum the number -15.56% and +16.06% respectively and with copper the chance -12.27% and +15.53% respectively, with lead the number +12.36% and -19.81% respectively. In case of electron flux in the same condition, the number -3.92% and +4.55% respectively without shielding material respectively, with aluminum the number +0.59% and +6.87% respectively, with copper the number -1.59% and +3.86% respectively, with lead the chance -5.15% and +4.00% respectively. Conclusion: In this study, we found that the required thickness of the shielding materials got thinner with low atomic number substance as the irradiation field is increasing. On the other hand, with high atomic number substance the required thickness had increased. In addition, bremsstrahlung radiation have an influence on low atomic number materials and high atomic number materials are effected by scattered electrons.