• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.998-1004
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• 2003

With starting materials of two different powder mixtures, $Al_2$(S $O_4$)$_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7) and ${\gamma}$-Al$_2$ $O_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7), whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were synthesized by using conventional and microwave heat-treatment. The effects of microwave, amount of flux and temperature on the growth of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were investigated by using X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). With increase of heat-treatment temperature and amount of flux, the size of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles increased in both conventional and microwave heat-treated samples. However, compared to the conventional heat-treated samples, whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were well grown for the microwave heat-treated samples.ted samples.

• Nuclear Engineering and Technology
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• v.4 no.4
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• pp.340-344
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• 1972

Isomeric ratios were measured for the capture of thermal neutron by $^{79}$ Br, $^{80}$ Se, $^{103}$ Rh, $^{115}$ In and $^{133}$ Cs as well as those of epi-cadmium neutron by $^{79}$ Br, $^{80}$ Se and $^{l33}$Cs. The measurements were performed by analysing decay curves obtained by ${\gamma}$-ray spectrometry after irradiation. The counting efficiency curve was determined by using the calibrated standard sources with overall uncertainties of about 1%. Isomeric ratios, given in $\sigma$ high spin/($\sigma$ high spin + $\sigma$ low spin), of $^{80, 80m}$Br, $^{81,81m}$Se, $^{014, 104m}$Rh, $^{116,116m}$In and $^{134, 134m}$Cs produced by thermal neutron activation were found to be 0.21$\pm$0.01, 0.14$\pm$0.02, 0.12$\pm$0.02, 0.69$\pm$0.07 and 0.058$\pm$0.004, respectively, Those values of $^{80, 80m}$Br, $^{81,81m}$Se, and $^{134, 134m}$Cs Produced by epi-cadmium neutron were found to be 0.19$\pm$0.02, 0.29$\pm$0.02 and 0.074$\pm$0.011, respectively. The experimental values obtained were compared with the theoretical values deduced from the statistical model. There were the general agreements between the theory and the experiment.t.

• Journal of Korean Society of Forest Science
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• v.25 no.1
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• pp.73-79
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• 1975

The Koran native economic and ornamental trees consisting 12 species of 4 gymnosperm families and 3 strains, 6 varieties and 18 species of 12 angiosperm families were irradiated by X-and ${\gamma}$-ray at three different dose rates; 1) acute, 2) semi-acute, and 3) chronic irradiation in order to know their radiosensitivities and the radition effects on mutation induction. Different materials such as seeds, cuttings, scions and plants of the above trees were used in this study, depended upon tree. Most of the materials irradiated showed a high radiosensitivity. The LD-50 of conifer trees ranged from 1.2kR to 13.2kR, averaging 5.4kR which was remarkably higher than field crops. On the other hand the LD-50 dose of hard wood trees ranged from 7.0kR to 18.5kR, averaging 12.7kR. All the tested trees were classified into several categories based upon the relative radiosensitivity of each species which was measured at the dose of LD-50. Variegation was most common among the induced mutants. The other mutations were albino, chlorophyll deficiency, deformed leaf and fruits. It was noticeable that giant-leaf bud-sport mutants were induced in Chinese chestnut (Castanea bungeana) and yellow leaf bud-sport ones appeared in oriental arborvitae (Thuja orientalis).

• Korean Journal of Breeding Science
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• v.43 no.2
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• pp.145-153
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• 2011

To develop new varieties of rapeseed (Brassica napus L.), the seeds of three varieties 'Naehan', 'Tammi', and 'Halla' were treated with proton ion beams and gamma rays (0~2,000 Gy), and then the characteristics of the mutants induced were examined up to $M_5$ generation to select the lines with fixed useful traits. In $M_5$ generation, we had selected several lines that were highly fixed for some useful traits such as plant height, maturity and flower size; one line with both earlier maturity and shorter stem than wild type, one line with only earlier maturity, two lines with shorter stem, one line with large flower, and one line with chlorophyll mutation. Among them, NP600-1-1-198-2 (induced from variety 'Naehan' was treated with proton ion beams 600 Gy) was superior for its distinction from the original variety, uniformity and stability. The unique characteristics of NP600-1-1-198-2 were dark green leaves, green stem, yellow flower, and black seed coat. Its flowering date was April 14, eight days earlier than its original variety, while seed maturity date was June 16 (five days earlier) and plant height 105 cm (shorter by 10 cm). NP600-1-1-198-2 has 52 silique per panicle, 6.2 cm silique length, 23 seeds per silique, 4.2 g per 1000 seeds and 45.9% oil content. The seed oil contained 67.8% of oleic acid, 16.7% of linoleic acid and 7.3% of linolenic acid but no erucic acid.

• Radiation Oncology Journal
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• v.2 no.1
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• pp.107-113
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• 1984

One hundred sixty one patients with the carcinoma of uterine cervix received curative radiotherapy at the Department of Therapeutic Radiology, Seoul National University Hospital between December, 1979 and December, 1982. According to FIGO classification; stage $I_a 1(0.6\%)\;1_b\;8(5.0\%),\;II_a\;31(19.3\%),\;II_b\;66(41.0\%),\;III_a\;3(1.8\;%),\;III_b\;46(28.6\%)\;and\;IV_a\;6(3.7\;%)$. The proportion of early stage cancer is too small because most of them treated by surgery. External beam whole pelvic irradiation was done first with 10MV x-ray or Co-60 gamma ray upto 4,000 or 5,000 rad for early and advanced cases, followed by one or two courses of intracavitary radiation using Fletcher-Suit Applicator loading c Cs-137. Supplementary external radiation to pelvic side wall to bring dose to 6,000 or 6,500 rads, if there is parametrial involvement or positive pelvic lymph node. Of the 161 Patients, 49 Patients were lost to follow-up but only 22 patients were lost in disease free state. And so, 86.3 percent of the patients were followed to time of recurrence or to date. The results are as follows ; 1. Locoregional control rates according to stage is: stage I $100\%,\;II_a\;90.3\;%,\;II_b\;75.8\%,\;III_a\;66.7\%,\;III_b\;58.7\%\;and\;IV_a\;16.7\%$, respectively. 2. Persistent or recurrent disease were localized in pelvic cavity in 32 of 50 patients and 6 had distant metastasis only. 3. Rectal bleeding was the most common complication and appeared mostly between 6 and 24 months after radiotherapy. Most of them had transient minor bleeding and only 2 patients needed transfusion and 1 patient needed colostomy due to rectovaginal fistula. 4. The 3 year disease free survival rate is: stage I $100\%,\;II_a\;78.0\%,\;II_b\;60.6\%,\;III_a\;66.7\;III_b\;46.3\%\;and\;IN_a\;16.7\%$, respectively.

• Progress in Medical Physics
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• v.9 no.1
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• pp.11-21
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• 1998

Circular metal electrodes were vacuum-deposited with chromium on the both sides of Teflon-FEP and PET film characteristic of electret and the physical properties of the two polymers were observed during an irradiation by gamma-ray from $\^$60/Co. With the onset of irradiation of output 25.0 cGy/min the induced current increased rapidly for 2 sec, reached a maximum, and subsequently decreased. A steady-state induced current was reached about in 60 second. The dielectric constant and conductivity of Teflon-FEP were changed from 2.15 to 18.0 and from l${\times}$l0$\^$-17/ to 1.57${\times}$10$\^$-13/ $\Omega$-$\^$-1/cm$\^$-1/, respectively. For PET the dielectric constant was changed from 3 to 18.3 and the conductivity from 10$\^$-17/ to 1.65${\times}$10$\^$-13/ $\Omega$-$\^$-1/cm$\^$-1/. The increase of the radiation-induced steady state current I$\^$c/, permittivity $\varepsilon$ and conductivity $\sigma$ with output(4.0 cGy/min, 8.5 cGy/min, 15.6 cGy/min, 19.3 cGy/min) was observed. A series of independent measurements were also performed to evaluate reproducibility and revealed less than 1% deviation in a day and 3% deviation in a long term. Charge and current showed the dependence on the interval between measurements, the smaller the interval was, the bigger the difference between initial reading and next reading was. At least in 20 minutes of next reading reached an initial value. It may indicate that the polymers were exhibiting an electret state for a while. These results can be explained by the internal polarization associated with the production of electron-hole pairs by secondary electrons, the change of conductivity and the equilibrium due to recombination etc. Heating to the sample made the reading value increase in a short time, it may be interpreted that the internal polarization was released due to heating and it contributed the number of charge carriers to increase when the samples was again irradiated. The linearity and reproducibility of the samples with the applied voltage and absorbed dose and a large amount of charge measured per unit volume compared with the other chambers give the feasibility of a radiation detector and make it possible to reduce the volume of a detector.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.61-68
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• 2007

To develop rice (Oryza sativa L.) cultivars to be planted on salt-affected sites, cell lines with enhanced proline content and resistance to growth inhibition by Azetidine-2-carboxylic acid (AZCA), a proline analogue, were screened out among calli irradiated with gamma ray of 50, 70, 90, and 120 Gy. The calli had been derived from embryo culture of the cultivar Donganbyeo. Selected AZCA resistant lines that had high proline accumulation were used as sources for selection of NaCl resistant lines. To determine an optimum concentration for selection of NaCl resistant lines, Donganbyeo seeds were initially cultured on the media containing various NaCl concentrations (0 to 2.5%) for 40 days, and 1.5% NaCl concentration was determined as the optimum concentration. One hundred sixteen salt-tolerant (ST) lines were selected from bulked 20,000 seeds of the AZCA resistant $M_{3}$ seeds in the medium containing 1.5% NaCl. The putative 33 lines ($M_{4}$ generation) considered with salt-tolerance were further analyzed for salt tolerance, amino acid and ion contents, and expression patterns of the salt tolerance-related genes. Out of the 33 lines, 7 lines were confirmed to have superior salt tolerance. Based on growth comparison of the entries, the selected mutant lines exhibited greater shoot length with average 1.5 times, root length with 1.3 times, root numbers with 1.1 times, and fresh weight with 1.5 times than control. Proline contents were increased maximum 20%, 100% and 20% in the leaf, seed and callus, respectively, of the selected lines. Compared to control, amino acid contents of the mutants were 24 to 29%, 49 to 143%, 32 to 60% higher in the leaf, seed and callus, respectively. The ratio of $Na^{+}/K^{+}$ for most of the ST-lines were lower than that of control, ranging from 1.0 to 3.8 for the leaf and 11.5 to 28.5 for the root, while the control had 3.5 and 32.9 in the leaf and root, respectively. The transcription patterns for the P5CS and NHXI genes observed by RT-PCR analysis indicated that these genes were actively expressed under salt stress. The selected mutants will be useful for the development of rice cultivar resistant to salt stress.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.247-255
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• 2021

The purpose of this study was to examine the radiation protection effect of protaetia brevitarsis larvae extracts known as antioxidant food. In this study 90 female rats were clssified in to 5 groups: NC Group, PBE Group, IR Group, PBE+IR Group and IR+PBE Group. In IR Group, 7 Gy of Co-60 gamma ray was irradiated to SD rat and protaetia brevitarsis larvae extracts were administered orally at 200 mg/kg once a day for 14 days. And then on the 1 day, 7 days, 21 days later after irradiation, changes in blood cell component, superoxide dismutase(SOD) activity, spleen index, histopathological evaluation of the ovary and uterus were observed. As a result, the PBE+IR Group (p<0.01, p<0.05) and IR+PBE Group (p<0.01, p<0.01) showed a significantly radiation protection than the IR Group in lymphocyte and red blood cell on the 21 days. It was also confirmed that SOD activity of PBE+IR Group (p<0.01) and IR+PBE Group (p<0.01) was significantly increased than the IR Group. In spleen index, PBE+IR Group (p<0.05) and IR+PBE Group (p<0.01) showed a significantly recovery than the IR Group. In histopathological observation, PBE+IR Group in the ovary and PBE+IR, IR+PBE Group in the uterus showed less inflammatory reactions of cystoplasm than the IR Group. Based on These results, It is judged that protaetia brevitarsis larvae Extracts have radiation protection effect against blood and reproductive. It is expected to be useful for research of radiation protection agent.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.194-201
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• 2015

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by $^{137}Cs$ gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity ($R^2$ > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.

• Journal of Chest Surgery
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• v.30 no.8
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• pp.739-746
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• 1997

A variety of experiments concerning the development of ideal prosthetic grafts for correcting circumferential tracheal defects have been performed. The requirements for an ideal tracheal prosthesis are impermeability to air, consistency to prevent collapse, and acceptance by the host tissue causing a minimum inflammatory reaction, allowing fibroblastic infiltration and epithelialization. The synthetic material, polyurethane(PU), is known as a biocompatible polymer with an inert component. In this study, the tracheal prosthesis was made from microporous PU(30 micrometer in diameter) coated with gelatin and reinforced with isoplastic rings. This procedure provides the prosthesis with a compression strength. The out side diame er of the prosthesis was 20 mm with a length of 30 mm. The gelatin used in the study was obtained from pig skin and immobilized and cross-linked by irradiation(60 Co gamma ray) to promote host tissue incorporation and render the prosthesis epithelization after implantation. Animal experiments using 10 mongrel dogs were performed to compare three kinds of prosthesis; gelatin coated polyurethane graft, uncoated polyurethane graft, and prosthesisf pericadium complex graft. After 6 weeks of implantation, the epithelialization of implants was seen on the gelatin-coated and prosthesisfpericadium complex grafts. Implanted prosthesis were complicated by airway obstruction due to anastomosis granuloma. Early tracheal stenosis was found in the uncoated graft group. Two kind of anastomosis techniques were tested on the gelatin-coated prosthesis. Everted anastomosis resulted severe granuloma than the inverted anastomosis. In the prosthesislpericadium complex graft, bacteria and inflammation at a anastomotic site was found. Based on these results, gelatin coated porous polyurethane trachea prosthesis is biocompatible and may be useful in clinical application with further investigation.