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        검색결과 19

        2.
        2023.11 구독 인증기관·개인회원 무료
        The demand for transportation is increasing due to the continuous generation of radioactive wastes. Especially, considering the geographical characteristics of Korea and the location characteristics of nuclear facilities, the demand for maritime transportation is expected to increase. If a sinking accident happens during maritime transportation, radioactive materials can be released into the ocean from radioactive waste transportation containers. Radioactive materials can spread through the ocean currents and have radiological effects on humans. The effect on humans is proportional to the concentration of radioactive materials in the ocean compartment. In order to calculate the concentration of radioactive materials that constantly flow along the ocean current, it is necessary to divide the wide ocean into appropriate compartments and express the transfer processes of radioactive materials between the compartments. Accordingly, this study analyzed various ocean transfer evaluation methodologies of overseas maritime transportation risk codes. MARINRAD, POSEIDON, and LAMER codes were selected to analyze the maritime transfer evaluation methodology. MARINRAD divided the ocean into two types of compartments that water and sediment compartments. And it was assumed that radionuclides are transfered from water to water or from water to sediment. Advection, diffusion, and sedimentation were established as transfer process for radionuclides between compartments. MARINRAD use transfer parameters to evaluate transer processes by advection, diffusion, and sedimentation. Transfer parameters were affected by flow rate, sedimentation rate, sediment porosity, and etc. POSEIDON also divided the ocean into two types that water and sediment compartment, each compartments was detaily divided into three vertical sub-compartment. Advection, diffusion, resuspension, sedimentation, and bioturbation were established as transport processes for radionuclides between compartments. POSEIDON also used transfer parameters for evaluating advection, diffusion, resuspension, sedimentation, and bioturbation. Transfer parameters were affected by suspended sediment rates, sedimentation rates, vertical diffusion coefficients, bioturbation factors, porosity, and etc. LAMER only considered the water compartment. It divided the water compartment into vertical detailed compartments. Diffusion, advection and sedimentation were established as the nuclide transfer processes between the compartments. To evaluated the transfer processes of nuclides for diffusion and advection, LAMER calculated the probability with generating random position vectors for radionuclides’ locations rather than deterministic methods such as MARINRAD’s transfer parameters or POSEIDON’s transfer rates to evaluate transfer processes. The results of this study can be used as a basis for developing radioactive materials’ ocean transfer evaluation model.
        3.
        2023.05 구독 인증기관·개인회원 무료
        As nuclear power plants are operated in Korea, low and intermediate-level radioactive wastes and spent nuclear fuels are continuously generated. Due to the increase in the amount of radioactive waste generated, the demand for transportation of radioactive wastes in Korea is increasing. This can have radiological effect for public and worker, risk assessment for radioactive waste transportation should be preceded. Especially, if the radionuclides release in the ocean because of ship sinking accident, it can cause internal exposure by ingestion of aquatic foods. Thus, it is necessary to analyze process of internal exposure due to ingestion. The object of this study is to analyze internal exposure by ingestion of aquatic foods. In this study, we analyzed the process and the evaluation methodology of internal exposure caused by aquatic foods ingestion in MARINRAD, a risk assessment code for marine transport sinking accidents developed by the Sandia National Laboratory (SNL). To calculate the ingestion internal exposure dose, the ingestion concentrations of radionuclides caused by the food chain are calculated first. For this purpose, MARINRAD divide the food chain into three stages; prey, primary predator, and secondary predator. Marine species in each food chain are not specific but general to accommodate a wide variety of global consumer groups. The ingestion concentrations of radionuclides are expressed as an ingestion concentration factors. In the case of prey, the ingestion concentration factors apply the value derived from biological experiments. The predator's ingestion concentration factors are calculated by considering factors such as fraction of nuclide absorbed in gut, ingestion rate, etc. When calculating the ingestion internal exposure dose, the previously calculated ingestion concentration factor, consumption of aquatic food, and dose conversion factor for ingestion are considered. MARINRAD assume that humans consume all marine species presented in the food chain. Marine species consumption is assumed approximate and conservative values for generality. In the internal exposure evaluation by aquatic foods ingestion in this study, the ingestion concetration factor considering the food chain, the fraction of nuclide absorbed in predator’s gut, ingestion rate of predator, etc. were considered as influencing factors. In order to evaluate the risk of maritime transportation reflecting domestic characteristics, factors such as domestic food chains and ingestion rate should be considered. The result of this study can be used as basis for risk assessment for maritime transportation in Korea.
        4.
        2023.05 구독 인증기관·개인회원 무료
        After Fukushima nuclear power plant accident in 2011, Concerns about accident of spent fuel pool increase. In Korea, the time of saturation of spent fuel pool is coming, but regulatory measures and safety evaluation are insufficient when occurring spent fuel pool accident. Thus, it is necessary to review of spent fuel pool accident in foreign countries to establish regulatory measures and safety evaluation of spent fuel pool accident suitable for domestic spent fuel pool. Therefore, we reviewed spent fuel pool accident that occurred at Fukushima Unit 4, SONGS Unit 2 and PAKS. In Japan, spent fuel pool accident occurred at Fukushima NPP in 2011. Tsunami was cause of the accident. Station Black Out occurred at Fukushima NPP and Emergency Diesel Generator lost their functions due to Tsunami. As a result, Loss of cooling happened in spent fuel pool at Fukushima NPP. For Unit 4, wall of spent fuel pool in Unit 4 was damaged due to hydrogen explosive, so loss of coolant in spent fuel pool of Unit 4 occurred. After the accident, the temperature of spent fuel pool increases to 75°C, but there was no damage to the spent fuel. In USA, spent fuel pool accident occurred at SONGS Unit 2 in 2013. The debris of nearby ocean is cause of the accident. The debris entered the system through a damaged Salt Water Cooling pump suction strainer. The debris obstructed flow through the Component Cooling Water heat exchanger and operation of Salt Water Cooling. The maximum spent fuel pool temperature during this event was 25.6°C. It was a value that satisfied the technical specifications of the SONGS NPP. In Ukraine, spent fuel pool accident occurred at PAKS in 2003. Unintentionally opened valve of cleaning tank is cause of the accident. Loss of coolant occurred in spent fuel pool of PAKS. Due to loss of coolant, spent fuels were exposed to the vapor state atmosphere, and oxidation occurred in the cladding tube of the spent fuel that rose to 1,400°C. In this study, Review of spent fuel pool accident in major foreign countries was conducted as basic studies for establishing regulatory measures and safety evaluation of spent fuel pool in Korea. Causes of each accident were different by structure of spent fuel pools. Result of this study will be contributed to establish safety measures of spent fuel pool accident suitable for domestic spent fuel pool facility.
        5.
        2022.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Interest in the use of semiconductor-based photocatalyst materials for the degradation of organic pollutants in a liquid phase has grown, due to their excellent performance and response to the light source. Herein, we fabricated a NiO-SiCTiO2 ternary structured photocatalyst which had reduced bandgap energy, with strong activation under UV-light irradiation. The synthesized samples were examined using XRD, SEM, EDX, TEM, DRS, EIS techniques and photocurrent measurement. The results confirmed that the two types of metal oxides were well bonded to the SiC fiber surface. The junction of the new photocatalyst exhibited a large number of photoexcited electrons and holes. The holes tended to oxidize the water and form a hydroxyl radical, which promoted the decomposition of methylene blue. The close contact between the 2D SiC fiber and metal oxide semiconductors expanded the scope of absorption wavelength, and enhanced the usability of the ternary photocatalyst for the degradation of methylene blue. Among three synthesized samples, the NiO-SiC-TiO2 showed the best photocatalytic effect, and was considered to have excellent photoelectron transfer due to the synergy effect between the metal oxide and SiC.
        4,000원
        9.
        2012.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to identify how a self-stretching exercise program affects pain for each body area, pain relief and job satisfaction for care workers. 20 of 40 care workers with musculoskeletal symptom were randomly selected and participated a self-stretching exercise program consisting of 15 motions. The intervention was done five times or more per weeks for 8 weeks and 1 session lasted within 15 minutes. 'Musculoskeletal symptom survey table' of the Korea Occupational Safety and Health Agency(KOSHA) and JDI(Job Descriptive Index) was used for pain on the musculoskeletal symptom and job satisfaction. Survey were done twice before and after the program. The result of this study showed that self-stretching exercise program group(SSPG) relieved from pain significantly in the shoulders(p<.01) and lumbar(p<.05), comparing to the non selfstretching exercise program group(NSPG). Although no significant difference on variations in the JDI appeared in SSPG, the significant reduction appeared from the colleague relationship and organization in NSPG(p<.05). SSPG showed the significant increase on variations in JDI from the job and organization comparing to NSPG. Especially, the improvement on satisfaction for the organization was shown(p<.05). Accordingly, the self-stretching exercise program for care workers can be said to positively affect the overall pain relief and increase on the JDI.
        4,000원
        11.
        2008.10 구독 인증기관·개인회원 무료
        We analyzed a portion of mitochondrial COI gene sequences (658 bp) to investigate the genetic diversity and geographic variation of the swallowtail butterfly, Papilioxuthus L., and the cabbage butterfly, Pieris rapae (Lepidoptera: Papilionidae). P. xuthus showed a moderate level of sequence divergence (0.91% at maximum) in 15 haplotypes, whereas P. rapae showed a moderate to high level of sequence divergence (1.67% at maximum) in 30 haplotypes, compared with other relevant studies. Analyses of population genetic structure showed that most populations are not genetically differentiated in both species. The distribution pattern of both species appears to be consistent with category IV of the phylogeographic pattern sensu Avise (Avise et al. 1987): a phylogenetic continuity, an absence of regional isolation of mtDNA clones, and extensive distribution of close clones. The observed pattern of genetic diversity and geographic variation of the two butterfly species seems to reflect the abundant habitats, abundant host plants, and flying abilities in connection with the lack of historical biogeographic barriers.
        12.
        2016.10 서비스 종료(열람 제한)
        Background : Agrimonia pilosa (A. pilosa) Ledebour has been registered in The Korean Herbal Pharmacopeia (KHP). In the recent study, A. Coreana showed antioxidant and anti-inflammatory effect. However, Studies of components in Agrimonia coreana (A. Coreana) Nakai was not much. So, we compared A. pilosa and A. coreana by High performance liquid chromatography (HPLC). we perfomed Thin layer chlromatography (TLC) including the anatomical characteristics by using microscope. Methods and Results : The anatomical characteristics of A. pilosa were similar to them of A. coreana. But, fascicular fivers of A. Coreana was broader than it of A. pilosa. TLC were performed to identify the Rutin and Apigenin-7-glucuronide compound. In the extract of Agrimoniae Herba, they were identified on the spot of Rf 0.2, 0.4 in Ethyl acetate - Formic acid – Water (8 : 1 : 1). The Rutin and Apigenin-7-glucuronide were analysed by HPLC/UV with Thermo Column (5 μm, 4.6 × 250 mm, C18), the column temperature at 40 ℃ and a diode-array detector (DAD) seted at 255 nm and 338 nm. The mobile phase was composed of water and acetonitrile containing 0.1% formic acid with the flow rate 1 mL/min. All compounds showed good linearity (R2>0.999) within test ranges. Agrimoniae herba was extrated by four kinds of extraction methods: MeOH, 50% MeOH, EtOH and water. The highest extraction rate occurred, when it was treated with 50% Methanol for refluxing extraction (60min). Content of Rutin was found to be 0.07±0.00 mg/g in A. pilosa and 0.02±0.00 mg/g in A. coreana. Content of Apigenin-7-glucuronide was found to be 0.12±0.00 mg/g in A. pilosa and 0.11±0.00 mg/g in A. coreana. Conclusion : The anatomical characteristics of A. pilosa were similar to them of A. coreana. Contents of Rutin and Apigenin-7-glucuronide in A. pilosa was higher than them in A. coreana slightly. But there were observed the similar patterns of Agrimonia pilosa Ledebour and Agrimonia coreana Nakai on the finger print anelysis.
        13.
        2014.07 서비스 종료(열람 제한)
        Internode elongation is an important agronomic trait in rice that is associated with lodging, yield, and flooding adaptation. We identified a novel rice mutant line showing shortened uppermost internode among the rice Ac/Ds insertional mutant population and named it shortened uppermost internode 4 (sui4). The phenotypes of F1 plants and F2 plants from the cross of sui4 with its original variety, Dongjin, indicated that the SUI4 gene shows incomplete dominance or semidominance. Because the Ds genotypes did not co-segregate with the sui4 phenotypes, we performed mapping of this gene with 273 F2 plants from a cross between sui4 and Milyang23. Primary mapping revealed that the SUI4 locus was located between the S07012 and S07015 markers on rice chromosome 7. Further fine mapping narrowed down the location of SUI4 to the 1.1-Mbp interval of RM1253-S07015. Using re-sequencing data of this mutant along with its original variety, Dongjin, and five other varieties, we found six sui4 specific SNPs occurred within the genic region of five genes in the fine-mapped interval. Among them, one SNP is in exon, while the other five SNPs are in intron. This SNP in exon occurred in the miR172 binding site of a gene encoding AP2 domain transcription factor, which seems to interrupt suppression of this gene activity by miR172. We isolated the genomic region of this gene from sui4 and transformed the wild type variety, Dongjin. The transgenic plants showed remarkably shortened internodes, which indicates that this AP2 domain transcription factor gene is the SUI4 gene.
        14.
        2013.08 서비스 종료(열람 제한)
        The Egr family of zinc finger transcription factors is rapidly induced by various mitogens and regulates cell growth, differentiation, and apoptosis. While it is clear that loss of Egr1 leads to anovulatory infertility due to LHβ deficiency in female mice, molecular function of Egr1 in male reproduction has not been clearly investigated. Here, we demonstrate that Egr1 acts as an intrinsic transcription factor in Leydig cells to regulate their proliferation and steroidogenesis in the testis as well as an extrinsic factor for male reproduction via LHβ transcription in the pituitary. Egr1 is predominantly expressed in spermatogonia and Leydig cells in immature testes and later detected in some of these cell types in mature testes. The fertility potential of Egr1(-/-) male mice is relatively deteriorated even at 2 month-old age and aggravated with aging. The incidence of abnormalities of seminiferous tubules such as Sertoli cell only was dramatically increased with aging. The number and mean size of Leydig cells were significantly reduced in Egr1(-/-) testes. The impairment of Leydig cells is consistent with significant reduction in levels of testosterone and expression of factors critical for steroidogenesis such as StAR in Egr1(-/-) testes. Exogenous administration of hCG rapidly and transiently induced Egr1 expression in Leydig cells culture in vitro. hCG could reinstate reduced mean size of Leydig cells but not reduced number of Leydig cells and aberrantly low StAR expression, suggesting that Egr1 has critical functions for Leydig cell proliferation and their steroidgenesis. In addition, daily sperm production and in vitro fertilization (IVF) competence were significantly reduced, and apoptosis was facilitated in these mice. Furthermore, hCG administration to compensate for relatively low LH levels in Egr1(-/-) males could not restore the compromised reproductive phenotypes such as IVF competence and apoptosis in these mice. Interestingly, expression of Egr2, a member of Egr family, is significantly elevated in Egr1(-/-) Leydig cells suggesting that genetic compensation of Egr2 may alleviate phenotypic aberration of Egr1(-/-) male testes. Collectively, these results suggest that Egr1 act as an intrinsic transcription factor required for proliferation and steroidogenesis of Leydig cells to govern spermatogenesis in the testis.
        15.
        2013.07 서비스 종료(열람 제한)
        The THO/TREX complex mediates the transport of nascent mRNAs from the nucleus towards the cytoplasm in animals, and it has a role in small RNA-dependent processes in plants. Here we describe five mutant alleles of Arabidopsis thaliana THO2, whichencodes a core subunit of the plant THO/TREX complex. tho2 mutants present strong developmental defects resembling those in plants compromised in microRNA (miRNA) activity. In agreement, not only the levels of siRNAs, but also of mature miRNAs were reduced in tho2 mutants. As a consequence miRNA target mRNAs accumulated to higher levels than in wild type. Yeast two hybrid experiments showed that THO2 does not seem to interact with any of the known miRNA biogenesis components, implying a more indirect role of THOs in small RNA biogenesis. We also detected alterations in the splicing pattern of genes encoding Serine/Arginine-rich proteins in tho2 mutants, suggesting a previously unappreciated role of the THO/TREX complex in alternative splicing.