검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 14

        1.
        2023.11 구독 인증기관·개인회원 무료
        Domestic commercial low- and intermediate-level radioactive waste storage containers are manufactured using 1.2 mm thick cold-rolled steel sheets, and the outer surface is coated with a thin layer of primer of 10~36 μm. However, the outer surface of the primer of the container may be damaged due to physical friction, such as acceleration, resonance, and vibration during transportation. As a result, exposed steel surfaces undergo accelerated corrosion, reducing the overall durability of the container. The integrity of storage containers is directly related to the safety of workers. Therefore, the development of storage containers with enhanced durability is necessary. This paper provides an analysis of mechanical properties related to the durability of WC (tungsten carbide)-based coating materials for developing low- and intermediate-level radioactive waste storage containers. Three different WC-based coating specimens with varied composition ratios were prepared using HVOF (high-velocity oxy-fuel) technique. These different specimens (namely WC-85, WC-73, and WC-66) were uniformly deposited on cold-rolled steel surfaces ensuring a constant thickness of 250 μm. In this work, the mechanical properties of the three different WCbased coaitng materials evaluated from the viewpoints of microstructure, hardness, adheision force between substrate and coating material, and wear resistance. The cross-sectional SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) images revealed that elements W (tungsten), C (carbon), Ni (nickel), and Cr (chromium) were uniformly distributed within the each coating layers which was approximately 250 μm thick. The average hardness values of HWC-85 and HWC-73 were found to be 1,091 Hv (Vickers Hardness) and 1,083 Hv, respectively, while the HWC-66 exhibited relatively lower hardness value of 883 Hv. This indicates that a higher WC content results in increased hardness. Adhesion force between and substrates and coating materials exceeded 60 MPa for all specimens, however, there were no significant differences observed based on the tungsten carbide content. Furthermore, a taber-type abrasion tester was used for conducting abrasion resistance tests under specific conditions including an H-18 load weight at 1,000 g with rotational speed set at 60 RPM. The abrasion resistance tests were performed under ambient temperatures (RT: 23±2°C) as well as relative humidity levels (RH: 50±10%). Currently, the ongoing abrasion resistance tests will include some results in this study.
        2.
        2023.11 구독 인증기관·개인회원 무료
        This study focuses on the development of coatings designed for storage containers used in the management of radioactive waste. The primary objective is to enhance the shielding performance of these containers against either gamma or neutron radiation. Shielding against these types of radiation is essential to ensure the safety of personnel and the environment. In this study, tungsten and boron cabide coating specimens were manufactured using the HVOF (High-Velocity Oxy Fuel) technuqe. These coatings act as an additional layer of protection for the storage containers, effectively absorbing and attenuating gamma and neutron radiation. The fabricated tungsten and boron carbide coating specimens were evaluated using two different testing methods. The first experiment evaluates the effectiveness of a radiation shielding coating on cold-rolled steel surfaces, achieved by applying a mixture of WC (Tungsten Carbide) powders. WC-based coating specimens, featuring different ratios, were prepared and preliminarily assessed for their radiation shielding capabilities. In the gamma-ray shielding test, Cs-137 was utilized as the radiation source. The coating thickness remained constant at 250 μm. Based on the test results, the attenuation ratio and shielding rate for each coated specimen were calculated. It was observed that the gammaray shielding rate exhibited relatively higher shielding performance as the WC content increased. This observation aligns with our findings from the gamma-ray shielding test and underscores the potential benefits of increasing the tungsten content in the coating. In the second experiment, a neutron shielding material was created by applying a 100 μm-thick layer of B4C (Boron Carbide) onto 316SS. The thermal neutron (AmBe) shielding test results demonstrated an approximate shielding rate of 27%. The thermal neutron shielding rate was confirmed to exceed 99.9% in the 1.5 cm thick SiC+B4C bulk plate. This indicates a significant reduction in required volume. This study establishes that these coatings enhance the gamma-ray and neutron shielding effectiveness of storage containers designed for managing radioactive waste. In the future, we plan to conduct a comparative evaluation of the radiation shielding properties to optimize the coating conditions and ensure optimal shielding effectiveness.
        5.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the properties of the pitches. As the hydrogen pressure increased, the C/H ratio decreased, and the solubility in n-hexane increased. The mesophase pitch with entirely anisotropic domains of flow texture exhibited good meltspinnability. The mesophase carbon fibers obtained from the catalytically hydrogenated petroleum residue showed moderate mechanical properties.
        4,000원
        6.
        2005.06 구독 인증기관 무료, 개인회원 유료
        Cloned calves derived from somatic cell nuclear transfer (SCNT) have been frequently lost by sudden death at 1 to 3 month following healthy birth. To address whether placental anomalies are responsible for the sudden death of cloned calves, we compared protein patterns of 2 placentae derived from SCNT of Korean Native calves died suddenly at two months after birth and those of 2 normal placentae obtained from AI fetuses. Placental proteins were separated using 2-Dimensional gel electrophoresis. Approximately 800 spots were detected in placental 2-D gel stained with coomassie-blue. Then, image analysis of Malanie III (Swiss Institute for Bioinformatics) was performed to detect variations in protein spots between normal and SCNT placentae. In the comparison of normal and SCNT samples, 8 spots were identified to be up-regulated proteins and 24 spots to be down-regulated proteins in SCNT placentae, among which proteins were high mobility group protein HMG1, apolipoprotein A-1 precursor, bactenecin 1, tropomyosin beta chain, H+-transporting ATPase, carbonic anhydrase II, peroxiredoxin 2, tyrosine-rich acidic matrix protein, serum albumin precursor and cathepsin D. These results suggested that the sudden death of cloned calves might be related to abnormal protein expression in placenta.
        4,000원
        8.
        2016.05 서비스 종료(열람 제한)
        Background : For increasing saponin content of ginseng cultivated in shaded plastic house, this study was performed to investigate growth characteristics and saponin content of ginseng (Panax ginseng C.A. Mayer) according to foliar spray of germanium and water-soluble silicates processing. Methods and Results : Used a native species in this study is violet-stem variant that most commonly cultivated in ginseng’s farms. 1-year-old violet-stem variant was transplanted on March 24, 2015 and planting distance was 11 × 20 cm. Shading material of plastic house was used blue-white shading vinyl. The processing method of inorganic dissolved matter is as follows, we were diluted with germanium and water-soluble silicates to 500-fold, 1000-fold and investigated after foliar spray twice a month from May to September. The growth characteristics in above-ground part of 2-year-old ginseng was a good in the inorganic matters treatment compared to the control treatment, the difference of above-ground growth characteristics between the inorganic dissolved matters treatments was not significant. The growth characteristics in under-ground part of 2-year-old ginseng was a good in the inorganic matter treatments and root weight per plant in the 500-fold dilution of germanium was 12.4 g that increased by 29 % compared to the control (9.6 g). Crude saponin content of under-ground part was higher generally in inorganic matter treatments compared to the control (11.53 ㎎/g). In the 1000-fold dilution of water-soluble silicate and germanium (50:50), crude saponin content was the highest in 12.91 ㎎/g. Crude saponin content of above-ground part was higher generally in inorganic matter treatments compared to the control (61.76 ㎎/g). In the 1000-fold dilution of water-soluble silicate and germanium (50:50), crude saponin content was the highest in 65.69 ㎎/g. Conclusion : From the above results, we concluded that germanium and water-soluble silicates could be useful matters in promoting growth characteristics and saponin content of ginseng (Panax ginseng C.A. Mayer).
        9.
        2016.05 서비스 종료(열람 제한)
        Background : This study was performed to set proper soil moisture tension for promoting seed emergence and yield of ginseng when direct seeding cultivation of ginseng was carried out in shaded plastic house. Methods and Results : The test cultivars were used Cheonpung, Yeonpung, Geumpung and seeds were sown on November 20, 2013. Irrigation starting point was set to 30, 40, 50 kPa and irrigation breakpoint was set to 20 kPa. Ginseng was cultivated in clay loam soil and shading material of plastic house were used blue-white shading vinyl. The emergence rate of 3-year-old ginseng cultivars in accordance with soil moisture tension indicated Cheonpung 97.0%, Yeonpung 95.0%, Geumpung 95.3% in each 50 kPa, 50 kPa, 30 kPa. In general, emergence rate of ginseng was higher tendency in 50 kPa (93.3∼97.0%). The average absolute soil moisture content during the growing season indicated a moisture content of 19.3% (30 kPa), 17.9% (40 kPa), 16.2% (50 kPa). Looking at the growth characteristics in above-ground part of 3-year-old ginseng cultivars according to soil moisture tension, Yeonpung, Cheonpung and Geumpung were good growth tendency in each 30kPa, 40kPa, 50kPa. On the other hand, looking at the growth characteristics in underground part of 3-year-old ginseng cultivars according to soil moisture tension, Cheonpung, Geumpung and Yeonpung were good growth tendency in each 30kPa, 40kPa, 50kPa. Yield per 10a was indicated that Yeonpung was the highest in the 50kPa to 456kg. Yield per 10a of Cheonpung and Geumpung indicated 347kg, 263kg in each 30kPa, 50kPa. Conclusion : From the above results, we concluded that ginseng(Panax ginseng C.A. Mayer) seems to be a difference of growth characteristics according to soil moisture tension. Therefore, it is need to manage soil moisture for each ginseng cultivars
        10.
        2015.06 서비스 종료(열람 제한)
        A 31-year-old woman was transferred because of dyspnea that occurred immediately after cesarean section. Initial echocar-diography showed akinesia in apex to mid left ventricular (LV) wall with severe LV systolic dysfunction, which was pre-sumed to be stress-induced cardiomyopathy. Because the patient developed cardiogenic shock, we initially planned on inser-tion of an intra-aortic balloon pump. However, due to aggravation of cardiogenic shock and pulmonary edema, we had to resort to extracorporeal membrane oxygenation (ECMO) for cardiopulmonary support. In addition, an LV pigtail catheter was applied for decompressing the LV. Finally, she was successfully weaned from ECMO after recovery of LV function.
        11.
        2015.06 서비스 종료(열람 제한)
        Mannitol is commonly used to reduce intracranial and intraocular pressures and to prevent dialysis-disequilibrium syndrome. However, intravenous mannitol infusion in various cases has the potential to result in acute kidney injury (AKI). We present a case of mannitol-induced AKI that developed after low dose mannitol infusion and resulted in recovery after hemodialysis. A 66-year-old woman was admitted to the hospital with a diagnosis of left middle cerebral artery infarction. On hospital day 5, cerebral edema was observed on a follow-up MRI. D-mannitol 35 g was given intravenously every 8 hours. Four days later, serum creatinine levels were elevated from 1.2 mg/dL to 3.5 mg/dL. The serum osmolal gap was found to be 52.4 mosm/kg H2O and urine output was reduced from 2.78 mL/kg/h to 0.69 mL/kg/h over three days. Hemodialysis over 2 hours was performed and renal function subsequently improved to baseline function. A potential risk of AKI exists even with low dose mannitol infusion in patients with advanced age, underlying renal impairment, and concomitant use of nephrotoxic agents. Mannitol-induced AKI may be rapidly reversed by short-term hemodialysis.
        12.
        2013.03 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 감태 효소 추출물과 그것의 폴리페놀 추출물의 화장품 원료로서의 효능을 알아보기 위하여 항산화, 항당화, 미백, 항염 효과와 관련된 실험을 실시하였다. 감태 효소 추출물과 폴리페놀 추출물은 강력한 라디컬 소거능을 가지고 있으며 BSA/Glucose 시스템에서 최종당화생성물의 형성을 저해하는 항당화 활성과 타이로시네이즈 저해를 통한 우수한 미백력을 가지고 있음을 확인하였다. 또한 두 추출물 모두 세포 내에서 PGE2와 NO 생성 저해를 통한 항염 효과를 나타내었다. 이러한 결과를 종합해 볼 때, 감태 효소 추출물과 그 폴리페놀추출물은 화장품 원료로서의 응용 가능성이 있을 것으로 사료된다.
        13.
        2012.12 KCI 등재 서비스 종료(열람 제한)
        Compared to wide ranges of genetic variation of natural populations, very limited Miscanthus cultivar has been released. This study was the first report on the development of Miscanthus cultivar by means of radiation breeding. Seeds of M. sinensis were initially exposed to gamma rays of 250 Gy for 24 h, generated from a 60Co gamma-irradiator. The irradiated seeds were sown and then the highly tiller-producing mutants were selected for this study. Biomass-related parameters including tiller number, plant height, stem diameter, and leaf number were measured. Ploidy level and internal transcribed spacer (ITS) were investigated to characterize the mutants compared to wild type (WT) Miscanthus. Plant height and tiller number were negatively related, where multi-tillering mutants were relatively short after 4 month growth. However stem diameter and leaf number were greater in mutants. All the materials used in this study were diploid, implying that the mutants with greater tiller numbers and stem diameter were not likely related to polyploidization. Based on the sequence of ITS regions, the mutants demonstrated base changes from the gamma irradiation where G+C content (%) was decreased in the ITS1, but increased in ITS2 when compared to WT sequence. ITS2 region was more variable than in ITS1 in the mutants, which collectively allows identification of the mutants from WT. Those mutants having enhanced tillers and allelic variations might be used as breeding materials for enhanced biomass-producing Miscanthus cultivars.
        14.
        2004.06 KCI 등재 서비스 종료(열람 제한)
        This experiment was conducted to investigate the variation of nitrogen use efficiency, nitrogen uptake efficiency, physiological utilization efficiency and their relationships with growth characteristics in the 28 Korean rice cultivars. Nitrogen use efficiency of 28 rice cultivars was 47.74, nitrogen uptake efficiency was 0.71, and physiological utilization efficiency was 68.76 in average. Nitrogen use efficiency of rice cultivars had low variation ranged from 44.09 to 51.91, but nitrogen uptake efficiency were relatively high variation from 0.51 to 0.90, and physiological utilization efficiency was from 51.71 to 94.26. The high efficient group in nitrogen uptake efficiency whose value was calculated above 0.80 included Daeanbyeo, Seojinbyeo, Ansungbyeo, Dongjinbyeo, and Hwaanbyeo, while the low efficient group with below 0.60 was Kwanganbyeo, Sampyeongbyeo, Soorabyeo, and Hwasungbyeo. Hwasungbyeo, Sampyeongbyeo, Soorabyeo for physiological utilization efficiency were more efficient cultivars, while Daeanbyeo, Seojinbyeo, Ansungbyeo were less efficient cultivars. Nitrogen uptake efficiency had positive correlation coefficients between dry matter weight of plant (0.842** ), leaf area index (0.761** ), and leaf nitrogen content (0.599** ), respectively. Therefore, the dry matter weight of rice plant and leaf area index was important characters to evaluate nitrogen uptake efficiency in rice cultivars. Also, more efficient cultivar in nitrogen uptake had higher chlorophyll meter value, which was appeared dark green color.