• Journal of radiological science and technology
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• v.46 no.1
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• pp.23-28
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• 2023

The purpose of this study is to see the radiation protection effect of the oral injected Dendranthema zawadskii var. latilobum (Maxim.) Kitam. extracts on the small intestine and uterus of female SD Rat as a natural radiation protection agent. The experimental group was divided into four groups: Normal Control group (NC group), Injected Dendranthema zawadskii var. latilobum (Maxim.) Kitam. extracts group (DZ group), irradiated group after injecting Dendranthema zawadskii var. latilobum (Maxim.) Kitam. extracts (DZ+IR group). The whole body of SD Rat was irradiated with gamma-ray 10Gy, and the administration of oral Dendranthema zawadskii var. latilobum (Maxim.) Kitam. Extract was 2 cc (71.56 mg/day/kg) once a day for 2 weeks. For this study, chages in blood cell levels, SOD assay, small intestine and uterus were observed. In the 21st white blood cell level, the DZ+IR group recovered to a normal level, and the IR group didn't. The IR group villus length was lower than other groups on Day 1. IR group was partially recovered, and DZ+IR group was recovered like the NC group on Day 21. In the case of the first-day endometrium, the IR group was thin and the boundary was cloudy, and the DZ+IR group was thicker and the boundary was clearer than the IR group. Day 21 IR group still did not recover, and DZ+IR group recovered like NC group. This is believed to have radiation protection effects in the blood cells and small intestine and uterus of the irradiated female SD Rat, and is expected to be useful for the study of natural radiation protection materials.

• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.237-247
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• 1993

Activity ratio of two radioactive primary fission products which had sufficiently different half-lives was expressed as functions of cooling time and irradiation histories in which average burnup, irradiation time, cycle interval time and the dominant fissile material of the spent fuel were included. The gamma-ray spectra of 36 samples from 6 spent PWR fuel assemblies irradiated in Kori unit-1 reactor were obtained by a spectrometric system equipped with a high purity germanium gamma-ray detector. Activity ratio $^{l44}$Ce $^{l37}$Cs, analyzed from each spectrum, was used for the calculation of cooling time. The results show that the radioactive fission products $^{l44}$Ce and $^{l37}$Cs are considered as useful monitors for cooling time determination because the estimated cooling time by detection of activity ratio $^{l44}$Ce $^{l37}$Cs agreed well with the operator declared cooling time within relative difference of $\pm$5 % despite the low counting rate of the gamma-ray of $^{l44}$Ce (about 10$^{-3}$ count per second). For the samples with several different irradiation histories, the determined cooling time by modeled irradiation history showed good agreement with that by known irradiation history within time difference of $\pm$0.5 year. From this result, it would be expected to be possible to estimate reliably the cooling time of spent nuclear fuel without the exact information about irradiation history. The feasibility study on identification of and/or sorting out spent nuclear fuel by applying the technique for cooling time determination was also performed and the result shows that the detection of activity ratio $^{l44}$Ce $^{l37}$Cs by gamma-ray spectrometry would be usefully applicable to certify spent nuclear fuel for the purpose of safeguards and management in a facility in which the samples dismantled or cut from spent fuel assemblies are treated, such as the post irradiation examination facility.mination facility.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.305-313
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• 2015

After Fukushima Daiichi nuclear disaster in 2011, study and maintenance of monitoring systems have been made at home and abroad. As concerns about radioactive contamination of water have increased in Korea, update of maintenance of managing radioactive materials in water is being made mainly by Ministry of Environment. In this study, we analysed current state of monitoring system modification in Japan, the country directly involved and neighboring country. According to the result, Japan modified the legislations first. Then Ministry of Education, Culture, Sports, Science and Technology (MEXT) provides theoretical background of radiological monitoring. And Ministry of the Environment actually watches state of water pollution in public waters and underground water. Finally related agencies like local government are monitoring current state of radioactive contamination in water environment. By region, local monitoring stations share the investigation of the whole country. Also, additional monitoring is running around nuclear facilities. After Fukushima disaster, monitoring for area near Fukushima is added. Among the reference levels, management target value of drinking water and tap water is 10 Bq/kg, and those of public water and underground water are 1 Bq/L. Measuring intervals varied from every hour to once a year, regularly or irregularly depending on the investigation. The main measuring items are air dose rate, gross ${\alpha}$, gross ${\beta}$, ${\gamma}$ radionuclide, Cs-134, Cs-137, Sr-89, Sr-90, I-131, and so on. In comparison, regulations about general public water in Korea need to be modified, while those about area near nuclear facility and drinking water are organized well. In future, therefore, domestic system would be expected to be modified with making reference to the guidelines like WHO's one. As good case of applying international guideline to domestic environment, Japanese system could be a reference when general standard of radioactivity in public water is made in Korea.

• Advances in concrete construction
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• v.17 no.3
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• pp.151-158
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• 2024

The calculation of the natural frequencies versus Young's modulus of carbon nanotubes with modified continuum shell is the subject of current research. When designing these tubes, it is important to understand their frequencies because excessive vibrations might cause fatigue. These tubes are designed and built to meet specific needs and have been suitably modified to investigate their vibratory response. There are numerous uses for carbon nanotube free vibration analysis in the mechanical sciences. The fundamental frequency with Young's modulus for clamped-free and simply supported end conditions, which is connected to the carbon nanotubes, is calculated theoretically for chiral single carbon nanotubes. When Young's modulus rises, so does the frequency curve pattern. Young's modulus influences the single-walled carbon nanotube's dynamic response by simulating it as a modified continuum shell. The Young's modulus of chiral tube and the value of frequency increased as the chiral tube's index increased. The results are checked against past studies to ensure the problem's validity and are determined to be accurate.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.3
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• pp.179-189
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• 2014

Pyroprocessing has been developed for the purpose of resolving the current spent nuclear fuel management issue and enhancing the recycle of valuable resources. An electrolytic reduction of the pyroprocessing is a process to reduce oxides into metals using LiCl as an electrolyte and requires a post-treatment process due to the inclusion of residual salt in porous metal products. A vacuum distillation has been adopted for various molten salt systems and could be applied to the post-treatment process of the electrolytic reduction. The residual salt in the metal products includes LiCl, alkali chlorides, and alkaline earth chlorides. In this paper, vapor pressures of chlorides have been estimated and the composition changes on the residual liquid during the vacuum distillation process have been calculated. A model combining a material balance and vapor-liquid equilibrium relations has been proposed under a constant vapor discharging flow rate and liquid composition changes have been calculated using the vapor pressures with respect to a dimensionless time. The behaviors have been compared with temperature and molten salt composition changes to simulate the process condition variation. The distillation of the residual salt has been dominated by LiCl which is the main component of the salt and CsCl of which vapor pressure is higher than that of LiCl would be readily removed. RbCl exhibits similar vapor pressure with LiCl and maintains its composition. However, $SrCl_2$ and $BaCl_2$ of which vapor pressures are much lower than that of LiCl are concentrated with time and expected to be possibly precipitated during the distillation when the initial compositions are increased.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.359-367
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• 2016

Background: As new legislation has come into force implementing radiation safety management for the use of naturally occurring radioactive materials (NORM), it is necessary to establish a rapid and accurate measurement technique. Measurement of $^{238}U$ and $^{232}Th$ using conventional methods encounter the most significant difficulties for pretreatment (e.g., purification, speciation, and dilution/enrichment) or require time-consuming processes. Therefore, in this study, the applicability of ED-XRF as a non-destructive and rapid screening method was validated for raw materials and by-product samples. Materials and Methods: A series of experiments was conducted to test the applicability for rapid screening of XRF measurement to determine activity of $^{238}U$ and $^{232}Th$ based on certified reference materials (e.g., soil, rock, phosphorus rock, bauxite, zircon, and coal ash) and NORM samples commercially used in Korea. Statistical methods were used to compare the analytical results of ED-XRF to those of certified values of certified reference materials (CRM) and inductively coupled plasma mass spectrometry (ICP-MS). Results and Discussion: Results of the XRF measurement for $^{238}U$ and $^{232}Th$ showed under 20% relative error and standard deviation. The results of the U-test were statistically significant except for the case of U in coal fly ash samples. In addition, analytical results of $^{238}U$ and $^{232}Th$ in the raw material and by-product samples using XRF and the analytical results of those using ICP-MS ($R^2{\geq}0.95$) were consistent with each other. Thus, the analytical results rapidly derived using ED-XRF were fairly reliable. Conclusion: Based on the validation results, it can be concluded that the ED-XRF analysis may be applied to rapid screening of radioactivities ($^{238}U$ and $^{232}Th$) in NORM samples.

• Journal of radiological science and technology
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• v.38 no.2
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• pp.163-170
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• 2015

The interest of the people in the radioactive contamination of the water has increased significantly and the study about analysis and management of radioactive materials are being actively conducted. And monitoring spots have been expanded to the range of public water as well as drinking water by publishing the rule of drinking water quality standards and examination in the Environmental Enforcement Ordinance No. 553 of Korea. In this study, US EPA was investigated as the foreign advanced cases and the way that is appropriate for the Korea was sought by analyzing investigate radionuclide, interval and management. As a result, in the selection part of investigate radionuclide, geological survey, status of nuclear power plants and the presence of the use of artificial radionuclides of the Korea should be investigated and additionally after the selection of a few radionuclides, the systems should be extended to cover all possible radionuclides by considering radioactive pollution levels in humans may be exposed due to the annual drinking water. In the part of the investigate interval, the concept(MCL, DL) should be set up for preventing concentration detection of above MCL and it needs to the maintenance and management. For example, when the concentration is more than MCL, it should be investigated on a quarterly and when the concentration is lower than MCL, it should be investigated to each different interval and management. And the US EPA divided the management area and make the roadmap for managing drinking water. The each classified area has been organized to match the state budget and labor force and the individual data have been managed effectively by HPGe, the NaI, TLD and so on.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.1
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• pp.25-31
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• 2017

The objective of this study is to find the failure factors of venture companies. We analyze 210 troubled venture companies, all of which have been under guarantee from the Korea Technology Finance Corporation over the last three years. Methods of analysis for failure factors are as follows. First, we categorize the failure factors into the four different types based on growth and profitability indicators in the financial statements of targeted venture companies. Then we analyzed the failure factors of the subject companies based on the troubled guarantee reports made by the Korea Technology Finance Corporation. If a venture company under its guarantee program falls into insolvency, the Korea Technology Finance Corporation make the troubled guarantee report to find out the failure factors and evaluate the recovery potentials. We identify 374 failure factors of venture companies through the analysis. The most prominent among them are deteriorating of business environments (79 factors) and decreasing or withdrawing orders from major suppliers (54 factors) due to bankruptcies or change in business plans. They are followed by slowing collection of accounts receivable (31 factors), dropping or frozen product price (24 factors) due to intensifying competition and escalating pressures from major suppliers, rising raw material costs both at home and abroad (21 factors). In addition, the nuclear power plant disaster in Japan, shut-down of the Kaesong Industrial Complex and subsequent lawsuits, delay in technology development projects, high cost-low efficiency management structure, etc., are also revealed as new factors causing trouble for venture companies.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.700-708
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• 2013

Pyroprocessing has been developed for the purpose of resolving the current spent nuclear fuel management issue and enhancing the recycle of valuable resources. Pyroprocessing has been developed with the dry technologies which are performed under high temperature conditions excluding any aqueous processes. Pyro-processes which are based on the electrochemical principles require pretreatment processes and a voloxidation process is considered as a pretreatment step for an electrolytic reduction process. Various kinds of gas conditions are applicable to the voloxidation process and the understanding of Cs behavior during the process is of importance for the analyses of waste characteristics and heat load on the overall pyroprocessing. In this study, the changes of chemical compounds with the gas conditions were calculated by analyzing gas-solid reaction behavior based on the chemical equilibria on a Cs-Te-O system. $Cs_2TeO_3$ and $Cs_2TeO_4$ were selected after a Tpp diagram analysis and it was confirmed that they are relatively stable under oxidizing atmospheres while it was shown that Cs and Te would be removed by volatilization under reducing atmosphere at a high temperature. This work provided basic data for predicting Cs behavior during the voloxidation process at which compounds are chemically distributed as the first stage in the pyroprocessing and it is expected that the results would be used for setting up material balances and related purposes.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.1-6
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• 2017

Reported some level of bacteria in areas that are well made contact in Radiology imaging room evaluate the importance of cleanliness in the hospital management of equipment to check for the presence of pathogenic bacteria. Gwang-ju and Jeol-la city and medium-sized hospitals in the material with a cotton swab and rub evenly Radiology selection cassette, a handle, Apron of the imaging apparatus having the most contact with patients from July 2016 to August 2016 as a target in place and special studios 6, and saline solution will placed in a test tube containing. The swab sample was diluted 1,000 times, you can see the bacteria and the intestinal bacterial selective medium Trypticase Soy Agar (TSA), Muller-Hinton Agar (MHA), Eosin-Methylene Blue (EMB), ENDO(BD, NJ, USA) then incubated smear to. In the incubator (incubator, SANYO, Japan) was observed after incubation of bacteria and counting the total number of bacteria also Colonies (colony) suspected intestinal bacteria were isolated and cultured on KIA medium (BD, NJ, USA). As a result, it was found that this came Gram positive Coccus A hospital handle the F hospital, from the C Gram positive Coccus cassette and handle the F hospital. The striking yellow coloring Staphylococcus aureus 110 agar (STA 110) in the medium sample, but it is suspected staphylococcal Coccus to the final identification in the laboratory is not a single specimen of the two samples from Gram positive Coccus biochemical identification Identification Kit is an API could not, it was thought to be non-Staphylococcus aureus was cultured on blood agar suggesting that (BAP) blood of dance. Dynamic tests were conducted biochemical API kit of the two samples were identified from Gram positive Coccus bacteria Escherichia coli (E. coli) is F hospital cassette was confirmed Eenterobacter cloaca in A hospital possession. Did not aggregate O-26, O-111, O-157 and the serum test was conducted in the laboratory from the E. coli F cassette hospital.