• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.331-341
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• 1995

The purpose of this study was to aid in the prediction of tumor cell tolerance to radiotherapy and/or chemotherapy. For this study, cell surviving curves were obtained for murine melanoma Bl6 cell line using semiautomated M1T assay. 2,4,6,8, 10Gy were irradiated at a dose rate of 210cGy/min using /sup 60/Co Irradiator ALOORADO 8. After irradiatior, B16 cell lines(2.5×10⁴ cells/ml) were exposed to bleomycin and cisplatin at concentration of 0.2㎍/㎖, 2㎍/㎖ and 20㎍/㎖ for I hour respectively. The viable cells were determined for each radiation dose and/or each concentration of drug. And they were compared to control values. The obtained results were as follows : 1. There was significant difference of surviving fraction at 4, 6, 8, 10Gy on B16 cell line(P<0.05). 2. There was significant difference of cytotoxicity between bleomycin and cisplatin at concentration of 0.2㎍/㎖ and 2㎍/㎖(P<0.05) on B16 cell line, but there was no significant difference of cytotoxicity at concentration of 20㎍/㎖ on B16 cell line. 3. There was significant difference of cytotoxicity of bleomycin after irradiation of 2Gy and 10Gy on B16 cell line(P<0.01). 4. There was significant difference of cytotoxicity of cisplatin at concentration of 20㎍/㎖ after irradiation on B16 cell line.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.343-362
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• 1995

The purpose of this study was to investigate chronic radiation effects on the basal cell of the rat tongue epithelium according to different irradiation timing. Forty-two female rats were devided into 5 experimental groups according to different irradiation timing and were irradiated single dose of 396cGy by MK cell irradiator using Cs-137. Experimental rats were sacrificed at the 2nd week, 4th week and 6th week after birth. The specimens were examined with light microscope and transmission electron microscope. The following results were obtained. 1. The first changes after irraditation were vacuoles. The vacuoles were chiefly observed in the cytoplasm, perinuclei area, and nuclei. 2. The most severe degenerative changes in the basal cell layer were observed in all experimental groups. ; cellular disarrangement, vacuole formation, widening of intercellular space, enlarged mitochondria & rER, and chromatin clumping were seen. 3. The cellular degenerative changes were most severe at the 4th week after birth in all experimental group, and the basal cell hyperplasia was seen at the 6th week in the most of experimental groups 4. The experimental groups 3 and 4 show more severe and more prolonged cellular degeneration than experimental groups 1 and 2, which were irradiated in pregnancy, and experimental group 5, which was irradiated after tongue maturation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.26 no.2
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• pp.45-63
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• 1996

In attempt to determine radiation effect on the mandibular condyle of the growing rat, 27 white female rats (Sprague-Dawley) were divided into 3 groups and irradiated respectively 5Gy, 10Gy, 20Gy using MK Cell Irradiator. Mandibular condyles from rats on the day of 1, 7, 14 after the irradiation day were obtained, sectioned sagittally and examined by light microscopy, and thereafter middle portion through anteroposterior direction on the sagittal plane was selected to examine the ultrastructural change by transmission electron microscopy. The obtained results are followings. 1. In the proliferative zone some cells showed little organelles in case of 5Gy irradiation, in addition the number of degenerative cells increased and in case of 10Gy irradiation, and in case of 20 Gy irradiation total number of cells decreased. 2. In the hypertrophic zone, narrowing of width and partial disorder in hypertrophic process were noted in case of 5 Gy irradiation, and more prominent narrowing of width and more irregular disorder in hypertrophic process in case of both 10Gy and 20Gy irradiation. 3. In the upper hypertrophic zone some chondrocytes seemed to be dying and the polarity of nuclei could not be seen, if any. 4. The periodic observation showed the severest change at day 7 and the signs of recovery at day 14 after irradiation.

• Textile Coloration and Finishing
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• v.24 no.4
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• pp.281-287
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• 2012

Poly(phenylene sulfide) films containing acetophenone as a photoinitiator were photocrosslinked under UV irradiation using a continuous UV irradiator. The gel fraction of the irradiated PPS in 1-Chloro naphthalene reached 94.7% with increasing UV energy and the photoinitiator concentration in the film upto $200J/cm^2$ and 12wt% respectively. Solid state $^1C$ NMR analysis suggested that the crosslinking occurred between the phenylene chains in PPS, indicating that the acetophenone may the phenylene hydrogens and subsequently adjacent polymer radicals could be recombined to form the crosslinked structure. The crosslinking improved the thermal behavior of PPS such as loss of $T_g$ and $T_c$, higher melting point and lower melting enthalphy as well as significantly higher peak pyrolysis temperature as much as $63.5^{\circ}C$. Surprisingly the tensile toughness of the most crosslinked PPS increased by 842%, resulting from the substantial enhancements in tensile modulus, strength and strain as much as 76%, 236% and 240% respectively. Also dynamic mechanical measurement indicated that the distance between crosslinks in the crosslinked PPS reached 85.3 g/mol corresponing to a crosslink density of 0.012 mol/g.

• Radiation Oncology Journal
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• v.3 no.1
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• pp.1-8
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• 1985

To determine the dose·survival and repair characteristics of the jejunal crypt cells, experimental study was carried out using total 70 mice. Single or split irradiations of 1,100 to 2,200 rad were delivered to whole bodies of $C_{57}$ BL mice, using a cesium 137 animal irradiator and those mice were sacrificed after 90 hours. The number of regenerating crypts per jejunal circumference was counted by a jejunal crypt cell assay technique and dose·response curve was measured. The results were as follows : 1. The average number of jejunal crypts per circumference in control group was 140. In a single irradiation group, the number of regenerated jejunal crypts was, 125, 56, 2 in each subgroup of 1,100 rad, 1,400 rad and 1,800 rad respectively. In split irraiation group, it was 105,44,2 in each subgroup of 1,400rad 1,800rad and 2,200rad respectively. 2. Mean lethal dose of mouse jejunal crypt cell was 167 and 169 rad respectively in a single and split irradiation. 3. Repair dose of sublethal damage was 280 rad. 4. Sublethal damage was completely repaired within 4 hours between the split dose of irradiation.

• Journal of Radiation Industry
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• v.4 no.4
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• pp.347-352
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• 2010

In this study, we addressed a novel nanosized curdlan-silica complex, which is curdlan bound to silica, for the development of a sustain-releasing micro element fertilizer formulation. The complex was obtained as follow steps; First, Curdlan polymer, sodium silicate ($Na_2SiO_3$) and isopropyl alcohol were dissolved in DDW. Next the resultant solution was irradiated by $^{60}Co$ gamma-irradiator (150 TBq of capacity; ACEL, Canada). Then $MgSO_4$ was treated with the resultant solution. The obtained colloidal solution was dried by freeze dryer. Finally, we obtained a novel nanosized curdlan-silica formulation containing $MgSO_4$ from the colloidal solution. The morphology of the complex was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanosized curdlan-silica complex has a particle size ranging from 20 to 80 nm and high stability. Our results suggested that the nano-complex can be applicable to use in various sustain-releasing formulation for pesticide delivery system (PDS).

• Journal of Radiation Industry
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• v.5 no.4
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• pp.305-311
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• 2011

We introduced a novel sustainable slow-releasing agrochemical formulation, a biopolymer bound to silica, for controlling plant diseases. The formulation was obtained through the following process. Curdlan, sodium silicate ($Na_2SiO_3$) and isopropyl alcohol were dissolved in DDW (Deionized-distilled water). The resultant solution was then irradiated using a $^{60}Co$ ${\gamma}$-irradiator (150 TBq of capacity; ACEL, Canada) at KAERI. The resultant solution was treated with phosphorous acid ($H_3PO_3$). Finally, we obtained a novel biopolymer-silica microsized formulation containing phosphorous acid ($H_3PO_3$) from the solution. The morphology of the complex was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM images revealed that the curdlan-silica formulation has a particle size ranging from 1 to $3{\mu}m$ with high stability. We also detected that $H_3PO_3$ was distributed within the formulation through energy dispersive X-ray spectroscopy (EDX) analysis. $H_3PO_3$ was sustain-released from the formulation in water. Based on our results, it seems effectively that one or two applications of the formulation during a cropping season will assist in controlling various plant diseases.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3383-3387
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• 2023

A new dyed polyvinyl alcohol (PVA) film dosimeter based on 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MMT) tetrazolium dye is proposed in this study for measuring high gamma radiation dose. Gamma cell irradiator that contains Co-60 gamma-ray source was used to expose the novel MMT-PVA films to different doses up to 25 kGy. The changed in optical property of irradiated and unirradiated films were characterized by UV-Vis spectrophotometer. The results show that the dose sensitive and the linear range of irradiated films were increased considerably with increase of MMT concentration from 1 to 5 mM. The dose response of dyed PVA film changed substantially with changing relative humidity (12-74%) as well as irradiation temperature (10-40 ℃). The absorbance of the unirradiated films does not change up to 10 days in dark while a significant increase in their absorbance was reported for similar films under fluorescent light. The irradiated dosimeters that kept in dark showed a perfect stability for 54 days. It was found that no obvious impact of dose rate on the irradiated MMT-PVA film dosimeters.

• Preventive Nutrition and Food Science
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• v.1 no.2
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• pp.262-268
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• 1996

In Korea, the health authorities and food industry emphasize the need of sanitary food production, which in mainly resulted from the recent growing of consumer's interest in the safety of food. For the reason, development of a new alternative technology to chemicals, currently used for decontamination and disinfestation, has become and urgent task in the domestic and worldwide food industry. Furthermore, the improvement of quality and manufacturing process of processed food is a requisite for winning the competition in export fields. Irradiation technology being practically applicable in the food industry has been well established on the basis of more than 40 years of R&D work in the fields of the increasing availability of food-stuffs, sanitary food production and quarantine treatment in the food trade. The wholesomeness of irradiation foods has been officially approved in 38 countries, of which 30 countries are commercially utilizing food irradiation technology. The first commercial irradiator in Korea(18.5PBq:500k{TEX}$Ci^{60}${/TEX} Co, max. cap; 4MCi) was established at Yeoju-gur, Kyung Ki-do with the technical assistance of Korea Atomic Energy Research Institute in June 1987. As of 1996, thirteen irradiated food groups (over 25 items)have been domestically approved for human consumption and an industrial irradiation facility is also available. However, the domestically approved for human consumption and an industrial irradiation facility is also available. However, the promotion of consumer acceptance to toward ir-radiated foods is considered as a confronted subject to be studied for a commercial utilization.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.27 no.2
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• pp.91-103
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• 1997

The purpose of this study was to aid in the prediction of tumor cell tolerance to radiotherapy and/or chemotherapy. For this study, cell surviving curves were obtained for human epidermoid carcinoma A-253 cell line using semiautomated MTT assay. 2,4,6,8,10 Gy were irradiated at a dose rate of 210 cGy/min using /sup 60/Co Irradiator ALDORADO 8. After irradiation, A-253 cell lines(2×10⁴cells/mil were exposed to bleomycin or cisplatin for 1 hour. The viable cells were determined for each radiation dose with/without 2 /lg/mi of drug at the 3rd day. And they were compared to control values. The results were obtained as follows : 1. The surviving curve with gentle slope was obtained after irradiation of 2, 4, 6, 8, 10 Gy on A-253 cell line. 2. The cytotoxicity of bleomycin or cisplatin at the concentration of 2㎍/ml was great on A-253 cell line. But, there was no significant difference between the cytotoxicity of bleomycin and that of cisplatin. 3. There were significant differences of surviving fractions after irradiation with 2㎍/mi of bleomycin compared with irradiation only on A-253 cell line. 4. There were significant differences of surviving fractions after irradiation with 2㎍/ml of cisplatin compared with irradiation only on A-253 cell line. 5. There were no significant differences of surviving fractions between the groups of irradiation with bleomycin and the groups of irradiation with cisplatin on A-253 cell line.