• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.61-70
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• 2002

Direct electron beam irradiation experiments on artificially contaminated soil by polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were performed to evaluate applicability of direct electron beam irradiation process for contaminated soil remediation. The removal efficiency of PAHs was about 97 % at 600 kGy and PCBs about 70 % at 800 kGy. PAHs were removed 27 % more, compared to PCBs although the absorbed dose was as low as 200 kGy. The contaminants decomposition was due predominantly to direct interaction of high-energy electrons and the target compounds rather than due to oxidation/reduction reaction by reactive intermediates. Radiolysis of electron beam may be able to decontaminate contaminated soil by toxic and recalcitrant organic compounds like as PAHs and PCBs effectively, but it may be economically uncompetitive. Thus, developments of post-treatment process of conventional site remediation technologies may be more practical and economical than direct radiolysis.

• Journal of the Korean Society of Radiology
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• v.10 no.6
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• pp.427-433
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• 2016

Recently increased use of high energy x-ray in radiation therapy, so therapeutic efficiency of tumors that located deep part also increased. However, photoneutron is problem which is generated caused by photoneuclear reaction. Photoneutron is continually required management because of that is more harmful than photon. In this regard, the study utilizing simulation of the Monte Carlo method is actively progress about photoneutron but measure is deficient. So this study was analyzed the correlation between the measured photon and photoneutron by radiation measurement device. As a result, photons were reduced when distance is farther and field size is smaller. But photoneutron were increased when field size is smaller and increased to a certain distance then reduced.

• Polymer(Korea)
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• v.29 no.1
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• pp.91-95
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• 2005

The PVA hydrogels were prepared by the chemical and irradiation method to improve the heat resistance of these hydrogels at the high temperature. The physical properties such as the gel content, the degree of swelling and the gel strength for the synthesized hydrogels were examined. Gel content increased as the chemical reaction time and the irradiation dose increased, and gel content of the hydrogels were higher when the two-steps of chemical and irradiation method were used rather than only the chemical method. Gel strength increased as the chemical reaction time increased, and as the irradiation dose decreased. The hydrogels prepared by the chemical reaction for 5 hours and the two-steps had the heat resistance at the high temperature.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.79-85
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• 2003

This study was intended to estimate Hp(10) recommended by the ICRU using the $CaSO_4:Dy,P$ element developed in the KAERI. For the estimation of Hp(10), TL response should be compensated properly through the energy range using filter materials since $CaSO_4:Dy,P$ is of severe photon energy dependent response. Various experiments and computations using Monte Carlo Code were carried out for designing filter satisfying the performance requirements of the ISO related to TL dosimeter. Under the completed filter, the relative response of $CaSO_4:Dy,P$ showed $0.75{\sim}1.0$ for photons in the range of $20{\sim}662keV$. Especially it was possible to reduce the thickness of front filter and simplify the filter combination with rear filter of larger diameter and to considerably improve angular dependence by introducing taper to the filler.

• Nuclear Engineering and Technology
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• v.5 no.3
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• pp.223-233
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• 1973

Thirty two different kinds of domestic plastic films for use in measuring high gamma-ray dose have been collected and their dosimetric characteristics investigated with the help of a Co-60 gamma radiation source. Among them a rigid polyvinyl chloride(PVC) film of 0.06mm in thickness which is manufactured by Lucky Chemical Co., Korea, seem to be the most suitable one for this purpose. The relation between optical density at 3100$\AA$ and radiation exposure in this PVC film was linear in the range of 0.6$\times$10$^{6}$ R to 1.3$\times$10$^{7}$ R, and also the film showed a good reproducibility within 9% under the standard experimental condition. The effect of absorbed dose, oxygen content of surrounding atmosphere and irradiation temperature have also been studied for this film. It appeared to have a good property in the dosimetrical point of view.

• The Journal of the Korea Contents Association
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• v.15 no.12
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• pp.347-354
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• 2015

Hypofractionated radiotherapy prescribes high dose once. Due to this there's a bad point that patients are exposed much dose in normal organ. But recently the study making up for a limit is continuing. Cause of preference of this kind of development of therapy technic and high-energy photon beam, patients can be exposed to additional radiation. Because photoneutron is created by photonuclear reaction. So, in this study I measured photoneutron and analyzed by DVH amounts of radiation from the treatment plan that was used to acute, metastatic pelvis cancer patients who was treated by hypofractionated radiotherapy applied IMRT. As a result, incidence of photoneutron based on the hypofractionated radiotherapy was not a big difference in proportion to the dose fractionation. Protective effects of normal organ by hypofractionated radiotherapy applying IMRT is relatively high compared to 3D CRT but also photoneutron was in created. So a proper treatment plan and a best therapy should be considerated.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.87-95
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• 2003

The fabrication process and the structure of PIN semiconductor detectors have been designed optimally by simulation for doping concentration and width of p+ layer, impurities re-contribution due to annealing and the current distribution due to guard ring at the sliced edges. The characteristics to radiation response has been also simulated in terms of Monte Carlo Method. The device has been fabricated on n type, $400\;{\Omega}cm$, orientation <100>, Floating-Zone silicon wafer using the simulation results. The leakage current density of $0.7nA/cm^2/100{\mu}m$ is achieved by this process. The good linearity of radiation response to Cs-137 was kept within the exposure ranges between 5 mR/h and 25 R/h. This proposed process could be applied for fabricating a PIN semiconductor detector for measuring individual dose.

• Radiation Oncology Journal
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• v.12 no.1
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• pp.1-8
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• 1994

When cells are exposed to low doses of a mutagenic or clastogenic agents. they often become less sensitive to the effects of a higher dose administered subsequently. Such adaptive responses were first described in Escherichia coli and mammalian cells to low doses of an alkylating agent. Since most of the studies have been carried out with human lymphocytes, it is urgently necessary to study this effect in different cellular systems. Its relation with inherent cellular radiosensitivity and underlying mechanism also remain to be answered. In this study, adaptive response by 1 cGy of gamma rays was investigated in three human lymphoblastoid cell lines which were derived from ataxia telangiectasia homozygote, ataxia telangiectasia heterozygote, and normal individual. Experiments were carried out by delivering 1 cGy followed by 50 cGy of gamma radiation and chromatid breaks were scored as an endpoint. The results indicate that prior exposure to 1 cGy of gamma rays reduces the number of chromatid breaks induced by subsequent higher dose (50 cGy), The expression of this adaptive response was similar among three cell lines despite of their different radiosensitivity. When 3-aminobenzamide, an inhibitor of poly (ADP-ribose) polymerase, was added after 50 cGy, adaptive responses were abolished in all the tested cell lines. Therefore it is suggested that the adaptive response can be observed in human lymphoblastoid cell lines, which was first documented through this study. The expression of adaptive response was similar among the cell lines regardless of their radiosensitivity. The elimination of the adaptive response by 3-aminobenzamide is consistent with the proposal that this adaptive response is the result of the induction of a certain chromosomal repair mechanism.

• Radiation Oncology Journal
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• v.19 no.4
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• pp.301-305
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• 2001

Purpose : This study was peformed for the evaluation of the feasibility and toxicity of hypofractionated radiation therapy for early glottic cancer Methods and Materials : From February 1999 to February 2000, 20 patients with Histologically confirmed Stage I, II glottic cancer were enrolled into this study. There were 18 males and 2 females, the median age of the patients was 59 years. The distribution of stage distribution was as fellows; T1aN0-16 patients, T1bN0-1 patient, T2N0-3 patients. Eighteen patients underwent laryngomicroscopic biopsy only, and two patients underwent laser cordectomy. All patients received radical radiation therapy (2.5 Gy per fraction, 24 fractions, total 60 Gy). Median duration of treatment was 36 days (range $31\~45\;days$). Results : Radiation therapy were well tolerated. Most common acute reactions were odynophagia and hoarseness, and these reactions resolved after radiation therapy. There were one case of RTOG grade 3 odynophagia $(5\%)$, six cases of grade 3 hoarseness $(30\%)$. Response of radiation therapy was evaluated one month after completion of treatment. All patients revealed complete response. During follow up, total three cases of treatment failure were detected. two cases were local recurrence in 10 and 13 months of radiation therapy and one case was local recurrence and distant metastasis in 2 months of radiation therapy. Conclusion : This hypofractionated radiation therapy schedule was feasible and effective for control of early glottic cancer But longer follow up time would be required to assess the long-term disease control and the late complication by shortening radiation therapy duration.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.43-49
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• 2005

A few studies have shown that the function of fusiform face area is selectively involved in the perception of faces including a race difference. We investigated the neural substrates of the face-selective region called fusiform face area in the ventral occipital-temporal cortex and same-race memory superiority in the fusiform face area by the event-related fMRI. In our fMRI study, subjects (Oriental-Korean) performed the implicit distinction of the race while they consciously made familiar-judgments, regardless of whether they considered a face as Oriental-Korean or European-American. For race distinction as an implicit task, the fusiform face areas (FFA) and the right parahippocampal gyrus had a greater response to the presentation of Oriental-Korean faces than for the European-American faces, but in the conscious race distinction between Oriental-Korean and European-American faces, there was no significant difference observed in the FFA. These results suggest that different activation in the fusiform regions and right parahippocampal gyrus resulting from superiority of same-race memory could have implicitly taken place by the physiological processes of face recognition.