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        검색결과 76

        1.
        2025.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적: 건성안은 스트레스에 의해 영향을 받을 수 있는 대표적인 안과 질환이다. 본 연구는 제8기 국민건강영양조사 (2019–2021) 원시자료를 활용하여, 직업에 의한 스트레스와 건성안 간의 관련성을 분석하고자 하였다. 방법 : 국민건강영양조사 제8기 자료 중 건성안 진단 유무와 스트레스 인지 정도에 응답한 3,781명을 대상으로, 성별, 연령, 학력 등의 일반적 특성과 건성안 진단 유무, 스트레스 인지 정도, 직업군별 건성안 유병률 간의 관계를 분석하였다. 통계적으로 p<0.050을 유의수준으로 설정하였다. 결과 : 여성에서 남성보다 건성안 유병률이 높았으며, 젊은 연령층과 고학력자에게서 유병률이 유의하게 높았 다. 스트레스 인지 수준이 높을수록 건성안 발생률도 증가하였고, 직업군별로도 유의한 차이를 보였다. 결론 : 직업에 의한 스트레스는 건성안 유병률 증가와 통계적으로 유의한 관련이 있었다. 특히 스트레스 수준이 높은 직업군에서 건성안 발생률이 높았으며, 이에 따라 직업환경 개선 및 예방 대책 마련의 필요성이 확인되었다.
        4,000원
        2.
        2025.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Aquatic exercise utilizing hot springs helps individuals with nonspecific knee pain by reducing joint stress and providing a safe environment for movement. It can improve muscle strength and balance, enhancing overall functional mobility. Objects: This study aims to examine the muscle strength of knee flexion, knee extension, dorsiflexion, and plantar flexion, as well as to investigate static and dynamic balance in middleaged females after performing hot spring aquatic exercise for 4 weeks. Methods: Twenty-two middle-aged females participated in the study. The participants performed hot spring aquatic exercise for 4 weeks. The hot spring aquatic exercise consisted of aquatic walking, aquatic stretching, aquatic side step, aquatic forward reach, aquatic squat, leg lift, and aquatic arm and leg rotation. Muscle strength was measured using microFET2, while static balance was assessed through the one-leg stance test, and dynamic balance was evaluated using the Y-balance test. This study utilized the paired t-test for statistical analysis, with a significance level set at 0.05. Results: The muscle strength of bilateral knee flexion showed a significant increase in the pre- and post-comparison (p < 0.05), and the muscle strength of bilateral knee extension also improved significantly (p < 0.05). In addition, a significant increase was observed in the muscle strength of bilateral dorsiflexion (p < 0.05). The one-leg stance test performed while supporting on the right leg showed a significant increase in the pre- and post-comparison (p < 0.05). Furthermore, the dynamic balance measurements performed while supporting on both the right and left legs demonstrated significant improvements in both legs when compared before and after the intervention (p < 0.05). Conclusion: In individuals with nonspecific knee pain, a 4-week hot spring aquatic exercise program can contribute to the improvement of lower extremity strength, as well as static and dynamic balance ability.
        4,200원
        3.
        2025.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적 : COVID-19 팬데믹 기간 동안 사회적 거리두기와 비대면 활동 증가로 인해 생활습관이 크게 변화하였다. 본 연구는 근거리 작업시간, 수면시간, 스트레스 수준의 변화가 비정시(근시, 원시, 난시) 발생에 미치는 영향을 분 석하고자 하였다. 방법 : 본 연구는 질병관리청 국민건강영양조사 제8기(2019~2021년도) 조사 중 2020년에 참여한 대상자들 중 만 40세 이상인 성인들을 대상으로 수행된 단면 연구이다. 연구 대상자는 안검진을 받은 성인 중 안과 질환이 없는 2,564명을 포함하였다. 굴절 이상은 등가구면굴절력을 기준으로 하였다. 결과 : 근거리 작업시간이 하루 4시간 이상인 그룹에서 근시 유병률이 유의하게 증가하였다. 반면, 1시간 이하 의 근거리 작업을 수행하는 그룹에서는 원시 유병률이 높았다(p<0.0001). 수면시간이 6~8시간인 그룹에서 근시 유병률이 가장 높았으며, 원시는 6시간 미만 그룹에서 높았다(p=0.0082). 스트레스 수준이 높은 그룹에서 근시 유 병률이 유의하게 증가하는 경향을 보였으나, 다중 로지스틱 회귀분석에서는 근거리 작업시간이 짧은 그룹에서 난시 유병률이 더 높은 경향을 보였으며(p<0.0001), 수면시간과 스트레스의 영향은 통계적으로 유의하지 않았다. 결론 : 본 연구 결과, 근거리 작업시간 증가가 근시 발생에 가장 큰 영향을 미치는 요인임이 확인되었으며, 수면 패턴과 스트레스 또한 비정시와 연관성을 가질 수 있음을 시사하였다. 이는 COVID-19 팬데믹과 같은 환경적 변 화가 시력 건강에 미치는 영향을 이해하고, 근시 예방 및 관리 전략을 수립하는 데 기여할 수 있다.
        4,000원
        4.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적: 본 연구는 실명을 유발하는 3대 주요 안질환의 연도별 유병률 추이를 관찰하고, 이들 질환의 인지율과 치 료율 비교와 관련 요인을 분석하고자 하였다. 방법: 질병관리청 국민건강영양조사 제8기(2019~2021년도) 조사에 참여한 대상자 중 만 40세 이상인 성인들을 대상으로 녹내장, 황반변성, 당뇨병성 망막병증의 유병률, 인지율과 치료율을 연도별로 비교하고 일반적 특성을 분 석하였다. 결과: 3대 주요 안질환의 연도별 추이를 보면 녹내장의 유병률은 매년 일정한 추이를 보이지만 당뇨망막병증의 유병률은 당뇨병 유병율과 함께 해마다 증가하고 있다. 연도별 인지율과 치료율은 다른 질환에 비해 녹내장이 높은 편이었으며, 황반변성의 인지율이 상당히 낮게 나타났다. 녹내장과 황반변성은 나이가 주요한 변수였으며, 황반변 성은 교육수준이 높아질수록 인지율과 치료율이 유의하게 높아지는 것으로 나타났다. 한편 당뇨병성 망막증의 경 우, 알코올 섭취는 인지율과 치료율을 감소시키는 것으로 나타났다. 결론: 본 연구를 통해 3대 주요 안질환의 인지율과 치료율에 대한 차이를 비교할 수 있었으며, 치료율에 미치는 다양한 요인 또한 확인할 수 있었다.
        4,000원
        5.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the effect of Distribution efficiency through the fishery production base distribution center (FPC) on the production site board facility was studied. FPC is a new distribution system for Korean fishery products that has been promoted in earnest since 2012, and in this study, the effect before and after the introduction of FPC was analyzed using the DID (Difference in Difference) model for the effect of FPC in the fishery industry. The results of analysis shows that in the case of Wando Geumil FPC, the volume and unit price of consignment sales decreased during the analysis period, which was statistically significant. In the case of Sokcho FPC, the volume of consignment sales decreased during the analysis period, which was statistically insignificant. But the unit price of consignment sales rose during the analysis period, which was statistically significant. In the case of Gyeongju FPC, the volume of consignment sales increased during the analysis period, which was statistically significant at the 90% confidence level. But the unit price of consignment sales fell during the analysis period, which was statistically significant.
        5,700원
        6.
        2014.11 구독 인증기관 무료, 개인회원 유료
        The number of CT gradually tends to increase, but radiation exposure includes higher exposure dose of patients than other test methods as the rate of 67% in the whole radiology tests. Exposure dose of patients has increased due to it and the second exposure has been done by scattered rays of other organs except for test sites. Especially, special shielding has not been done in gonad which is very sensitive to radiation in brain and chest CT. So this study tries to research the second exposure dose of the gonad and how to shield it in Chest CT which does not include it. It was intended for 20 male adults who are 30 years old and conduct chest CT. SIEMENS’s SOMATOM DEFINITION AS* was used as CT equipment. For the scanning conditions, The tube voltage is 120kv, the tube current is 90mAs, and the slice thickness is 3mm as the general chest CT conditions. CHIYODA TECHNOL CORPORATION’s FGD1000 was used as Glass dosimeter (PLD). A lead pad of 0.25mmPb was produced as the shielding board. For the research method, the shielding rate was compared by measuring exposure dose of the gonad before and after shielding and the usefulness of the shielding board was evaluated. The average exposure dose of symphysis pubica before shielding was 280.5μGy and the average exposure dose of coccyx was measured as 151.5μGy. The average exposure dose of symphysis pubica after shielding the gonad with a lead pad of 0.25mmPb was 42μGy and the average exposure dose of coccyx was measured as 41μGy.
        4,000원
        7.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2010년 구제역으로 많은 농가들이 피해를 입었으며, 발생원인과 바이러스 전파 과정에 대해서 명확한 원인과 근거를 찾을 수 없는 상태이다. 본 연구에서는 구제역의 발생에 있어서 불명확한 살처분 방지와 감염경로의 예측을 위한 지형적인 특성을 구명하고자, 2010년 경북지역을 대상으로 구제역이 발생한 농가 58개의 지형을 분류하였다. 분류요소는 농가가 위치한 고도, 경사도, 축사의 방향, 도로인접도, 마을인접도와 경사방향을 설정하여 발생농가의 지형적 자료를 각 항목에 분류하였다. 각 요소별 분류에서고도와 경사도, 하천인접도에서는 차이점을 나타내었으나, 축사방향 및 경사방향, 도로인접도, 마을인접도에서는 유사한 지형적인 특성을 보였다. 본 연구를 통하여 구제역 발생 농가만의 특수한 지형은 알수가 없었지만, 많은 변수들을 고려한 지형분류가 구제역 확산 방지와 예찰을 하기 위한 기초자료로 활용 될 수 있을 것으로 판단된다.
        4,000원
        8.
        2013.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        구제역 바이러스는 소나 돼지 등의 우제류 가축에 경구 또는 흡입 노출 등의 다양한 노출 경로를 통해 심각한 감염성을 유발하는 생물학적 유해인자로 국내 축산업 운영에 있어 막대한 경제적 손실을 초래하는 병원균들 중 하나다. 구제역 발병에 대한 사전적 예방 관리를 도모할 수 있는 조치 방안 중 하나는 공기를 통해 전파되는 구제역 바이러스 확산에 대해 수학적 모델 적용을 통해 예측된 분석 결과에 따라 설정될 수 있다. 대기 확산 모델들은 일반적으로 구제역 바이러스의 주요 전파 경로인 경구 및 접촉 감염의 노출 시나리오를 예측할 수는 없으나, 상대적으로 예측도가 높은 대기 확산 모델의 경우 공기 전파에 대한 구제역 바이러스의 위해성 관리 방안을 결정하는 데 주요 역할을 담당할 수 있는 유용가능한 수단으로 여러 나라에서 활용되어 왔다. 구제역 바이러스 전파를 억제하기 위한 엄격한 관리 방안 중 다량의 가축 살처분 방법은 축산 농가들에게 심각한 경제적 손실을 초래하여 심각한 경우 새로운 자립의 여건마저도 상실시킬 수도 있다. 반면 낮은 수준의 대응 방안은 향후 구제역 발생에 따른 추가적 피해를 근원적으로 억제할 수 없는 역학적 한계에 봉착할 수 있다. 본 연구는 구제역 바이러스의 기본 특성 및 발생 모델 적용에 따른 공기 중 전파의 감염 위험성 평가 관련 선행 문헌들을 고찰하였다. 또한 1970년대 이후 구제역 바이러스의 공기 전파 경로를 예측하기 위해 여러 나라에서 실제 활용된 다양한 대기 확산 모델들의 적용 사례 및 장/단점을 비교 분석하였다.
        4,200원
        11.
        2023.11 서비스 종료(열람 제한)
        This study explores the impact of metal doping on the surface structure of spent nuclear fuels (SNFs), particularly uranium dioxide (UO2). SNFs undergo significant microstructural changes during irradiation, affecting their physical and chemical properties. Certain elements, including actinides and lanthanides, can integrate into the UO2 lattice, leading to non-stoichiometry based on their oxidation state and environmental conditions. These modifications are closely linked to phenomena like corrosion and oxidation of UO2, making it essential to thoroughly characterize SNFs influenced by specific element doping for disposal or interim storage decisions. The research employs X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy to investigate the surface structure of UO2 samples doped with elements such as Nd3+, Gd3+, Zr4+, Th4+, and ε-particles (Mo, Ru, Pd). To manufacture these samples, UO2 powders are mixed and pelletized with the respective dopant oxide powders. The resulting pellet samples are sintered under specific conditions. The XRD analysis reveals that the lattice parameters of (U,Nd)O2, (U,Gd)O2, (U,Zr)O2, and (U,Th)O2 linearly vary with increasing doping levels, suggesting the formation of solid solutions. SEM images show that the grain size decreases with higher doping levels in (U,Gd)O2, (U,Nd)O2, and (U,Zr)O2, while the change is less pronounced in (U,Th)O2. Raman spectroscopy uncovers that U0.9Gd0.1O2-x and U0.9Nd0.1O2-x exhibit defect structures related to oxygen vacancies, induced by trivalent elements replacing U4+, distorting the UO2 lattice. In contrast, U0.9Zr0.1O2 shows no oxygen vacancy-related defects but features a distinct peak, likely indicating the formation of a ZrO8-type complex within the UO2 lattice. ε-Particle doped uranium dioxide shows minimal deviations in surface properties compared to pure UO2. This structural characterization of metal-doped and ε-particle-doped UO2 enhances our understanding of spent nuclear fuel behavior, with implications for the characterization of radioactive materials. This research provides valuable insights into how specific element doping affects the properties of SNFs, which is crucial for managing and disposing of these materials safely.
        12.
        2023.11 서비스 종료(열람 제한)
        Most of the C-14 produced is in the organic form, generated as methane (14CH4), methanol (14CH3OH), formaldehyde (14CH2O), and formic acid (14CO2H2). When analyzing C-14, it is transformed into the form of 14CO2, and its concentration is determined using LSC. Typical examples include the wet oxidation method, the combustion or Pyrolysis. The wet oxidation method uses strong acids and involves repeated operations, which generates large amounts of acid waste and secondary radioactive waste. The combustion method uses high temperatures, which requires an oxygen device. Pyrolysis also requires high temperature in a vacuum and catalysts. Catalysts are expensive because they are platinum-based. To compensate for these shortcomings, a C-14 analysis method using UV irradiation was developed. In this study, 100 mL of distilled water mixed with formic acid (CO2H2), potassium persulfate (K2S2O8), and silver nitrate (AgNO3) was irradiated with a 320-390 nm UV lamp to conduct a CO2 production reaction experiment. The UV range was measured using a photometer (UV Power puck II). The beaker was made of quartz in 150 mL size with three inlets : a temperature measurement, a sample inlet, and a collection tube connector. We changed the UV lamp used from a 450 W halogen lamp to a 100 W LED, which has a lower temperature and is safer. As a result of the experiment, CO2 bubbles were generated in the collection tube, due to the UV irradiation react, which uses oxidizer and catalysts. The maximum temperature of the solution irradiated with the LED UV lamp was less than 56°C. It confirmed the rate of bubble generation changed depending on the lamp distance, the amount of sample, oxidizer, and catalyst. In an experiment to confirm the reaction caused by heat, it was found that although a reaction occurred due to heat, the reaction was significantly lower than when using a UV lamp. The reproducibility experiment was conducted three times in total under the same conditions. It showed the same pattern. In the future, we plan to select mock samples, collect 14CO2 in Carbo- Sorb, and analyze them using LSC. The results of this research will be used as a technology to recover C-14 more safely and efficiently and will also be used to expand its application to the treatment of other wastes such as waste liquid and waste resin through simulated samples.
        13.
        2023.11 서비스 종료(열람 제한)
        Bis (2-ethylhexyl)phosphoric acid (HDEHP) is a renowned extractant, favored for its affinity to selectively remove uranium via its P=O groups. We previously synthesized HDEHP-functionalized mesoporous silica microspheres for solid-phase uranium adsorption. Herein, we investigated the kinetic and isothermal behavior of uranyl ion adsorption in mesoporous silica microspheres functionalized with phosphate groups. Adsorption experiments were conducted by equilibrating 20 mg of silica samples with 50 mL of uranium solutions, with concentrations ranging from 10 to 100 mgU L−1 for isotherms and 100 mgU L−1 for kinetics. Three distinct samples were prepared with varying HDEHP to TEOS molar ratios (x = 0.16 and 0.24) and underwent hydrothermal treatment at different temperatures, resulting in distinct textural properties. Contact times spanned from 1 to 120 hours. For x = 0.16 samples, it took around 50 and 11 hours to reach equilibrium for the hydrothermally treated samples at 343 K and 373 K, respectively. Adsorbed quantities were similar (99 and 101 mg g-1, respectively), indicating consistent functional group content. This suggests that the key factor influencing uranium adsorption kinetics is pore size of the silica. The sample treated at 373 K, with a larger pore size (22.7 nm) compared to 343 K (11.5 nm), experienced less steric hindrance, allowing uranium species to diffuse more easily through the mesopores. The data confirmed the excellent fit of pseudo-second-order kinetic model (R2 > 0.999) and closely matched the experimental value, suggesting that chemisorption governs the rate-controlling step. To gain further insights into uranium adsorption behavior, we conducted an adsorption isotherm analysis at various initial concentrations under a constant pH of 4. Both the Langmuir and Freundlich isotherm models were applied, with the Langmuir model providing a superior fit. The relatively high R2 value indicated its effectiveness in describing the adsorption process, suggesting homogenous sorbate adsorption on an energetically uniform adsorbent surface via a monolayer adsorption and constant adsorption site density, without any interaction between adsorbates on adjacent sites. Remarkably, differences in surface area did not significantly impact uranium removal efficiency. This observation strongly suggests that the adsorption capacity is primarily governed by the loading amount of HDEHP and the inner-sphere complexation with the phosphoryl group (O=P). Our silica composite exhibited an impressive adsorption capacity of 133 mg g-1, surpassing the results reported in the majority of other silica literature.
        14.
        2023.11 서비스 종료(열람 제한)
        Bisphenol-A, also known as BPA, is commonly used as a building block for epoxy and polycarbonate plastics. However, it has been recently identified as a major source of water pollution due to its release into the water from plastic products. BPA-based resins can also contaminate the water with high concentrations of BPA, which can enter the water bodies through production units and wastewater discharge. Photocatalysis, particularly the photo-Fenton process, is an effective method for wastewater treatment and degrading pollutants. Titanium dioxide (TiO2) is usually chosen based on its high photocatalytic properties and high performance. However, its wide band gap energy is a major issue for the photocatalytic process. This means that the catalyst can only exhibit high photocatalytic performance under UV-light irradiation and usually requires an acidic pH, which limits its use. In order to address the aforementioned issues, a visible-light photoactive photo-Fenton reaction has been successfully developed to degrade bisphenol A at natural pH using H2O2. The process was highly efficient, achieving complete degradation of phenol in just three hours of visible light irradiation with Cu-MOF. This environmentally friendly Fenton process has the advantage of occurring at natural pH levels with the presence of H2O2, providing a new perspective for efficient degradation. The photocatalyst was characterized using single X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV–vis diffuse reflectance spectroscopy (DRS).
        15.
        2023.05 서비스 종료(열람 제한)
        The density of molten salts is the most important property in the development of molten salt reactor (MSR). The density value measured through the experiment is also very valuable as a gold standard for the validation of the prediction models based on molecular dynamics or other computational methods. To the best of our knowledge, the experimental density data of the ternary NaCl-MgCl2- UCl3 salt system as a MSR candidate fuel salt have never been reported previously. In this study, density measurement experiment of high-temperature molten salt of NaCl-MgCl2 and NaCl-MgCl2- UCl3 was conducted using a previously-developed density measurement system based on the maximum bubble pressure (MPB) method. As a result of the experiment, the density value of 62NaCl- 18MgCl2-20UCl3 molten salt at 873 K was 2.62 g/cm3. A density prediction value of 2.65 g/cm3 at 873 K was derived from the obtained results based on the rule of additivity of molar volume method. The predictred density of 62NaCl-18MgCl2-20UCl3 was consistent with the experimental value within 1%. The density measuring system used in this study is promising for the validation of other multicomponent molten salt systems.
        16.
        2023.05 서비스 종료(열람 제한)
        Viscosity of molten salts is an essential property for the thermal hydraulic design and evaluation of molten salt reactor (MSR). Therefore, viscosity data is one of the fundamental physical property data required for safe process operation and countermeasures to severe accidents. In this study, based on our experience of developing a viscosity measurement system for high-temperature LiCl-KCl molten salt system, the viscosity of NaCl-MgCl2 and NaCl-MgCl2-UCl3 molten salts, which are considered promising salts in MSR, was measured. In order to investigate the physical properties of uranium in high-temperature NaCl-MgCl2 molten salt, a viscometer system for high-temperature viscosity measurement was specially designed. As a result of the measurement, the viscosity of the 58NaCl- 42MgCl2 molten salt was 2.73 cP at 838 K, 2.15 cP at 889 K, and 1.68 cP at 940 K. And the viscosity of 73NaCl-21MgCl2-6UCl3 molten salt was 3.79 cP at 877 K, 3.58 cP at 897 K, and 1.63 cP at 941 K. The repeatability of the measurement showed a precision of less than 3%. Although sufficientlyverified starting materials were not used, viscosity data were reported for the first time for NaCl- MgCl2-UCl3 molten salts.
        17.
        2023.05 서비스 종료(열람 제한)
        Confirmation of the thermal behavior of spent fuel is one of the important points in the management of high-level radioactive waste. This is because various fission products exist in spent nuclear fuel, and a management plan according to their behavior is required. Among the fission products, epsilon particles exist in the form of metal deposits and have a great influence on their physical and chemical properties. However, observing the thermal behavior of epsilon particles is important for understanding spent fuel behavior in thermally environment, but it is difficult to maintain a consistent thermal environment. In this work, we report the thermal behaviors study of uranium oxide with epsilon particle using in situ high temperature X-ray diffraction. We measured the variation of temperature on the size of crystalline, which is a cell parameter in the reaction process. And then, the change of lattice parameters is calculated by Rietveld refinement.
        18.
        2023.05 서비스 종료(열람 제한)
        Solubility and species distributions of radionuclides in domestic groundwater conditions are required for the safety assessment of deep underground disposal system of spent nuclear fuel (SNF). Minor actinides including Am contribute significant extents to the long-term radiotoxicity of SNF. In this study, the solubility of Am was evaluated in synthetic groundwater (Syn-DB3), which were simulated for the groundwater of the DB3 site in the KAERI Underground Research Tunnel (KURT). Geochemical modeling was performed based on the ThermoChimie_11a (2022) thermochemical database from Andra to estimate the solubility and species distributions of Am in the Syn-DB3 condition. Dissolved Am concentrations in the Syn-DB3 were experimentally measured under oversaturation conditions. Am(III) stock solution in perchlorate media was sequentially diluted in Syn-DB3 to prepare 8 μM Am(III) in Syn-DB3. The pH of the solutions was adjusted to be in the range of 6.4–10.5. A portion of the samples was transferred to quartz cells for UV-Vis absorption and time-resolved laser fluorescence spectroscopy studies and the rest were stored in centrifuge tubes. The absorption spectra of the samples were monitored over 70 days and the results suggest that Am colloidal particles were formed initially in all the samples and precipitated rapidly within two days. Over the experimental period of 236 days, small volume (10 μL) of the samples in the centrifuge tubes were periodically withdrawn after centrifugation (18000 rpm, 1 hr) for the liquid scintillation counting to measure the concentrations of Am dissolved in Syn-DB3. In the end of the experiments, pH of the samples was checked again and the final dissolved Am concentrations were determined after ultrafiltration (10 kDa) to exclude the contribution of colloidal particles. In the pH range of 8-9, which is relevant to the KURT-DB3 groundwater condition, the measured dissolved Am(III) concentrations were converged to around 10-8 M. These values are higher than the solubility of AmCO3OH:0.5H2O(s), but lower than that of AmCO3OH(am). There was no indication of transformation of the amorphous phase to the crystalline phase in our observation time window.
        19.
        2023.05 서비스 종료(열람 제한)
        Molten salts have gained significant attention as a potential medium for heat transfer or energy storage and as liquid nuclear fuel, owing to their superior thermal properties. Various fluoride- and chloride-based salts are being explored as potential liquid fuels for several types of molten salt reactors (MSRs). Among these, chloride-based salts have recently received attention in MSR development due to their high solubility in actinides, which has the potential to increase fuel burnup and reduce nuclear water production. Accurate knowledge of the thermal physical properties of molten salts, such as density, viscosity, thermal conductivity, and heat capacity, is critical for the design, licensing, and operation of MSRs. Various experimental techniques have been used to determine the thermal properties of molten salts, and more recently, computational methods such as molecular dynamics simulations have also been utilized to predict these properties. However, information on the thermal physical properties of salts containing actinides is still limited and unreliable. In this study, we analyzed the available thermal physical property database of chloride salts to develop accurate models and simulations that can predict the behavior of molten salts under various operating conditions. Furthermore, we conducted experiments to improve our understanding of the behavior of molten salts. The results of this study are expected to contribute to the development of safer and more efficient MSRs.
        20.
        2023.05 서비스 종료(열람 제한)
        Disposal of radioactive waste requires radiological characterization. Carbon-14 (C-14) is a volatile radionuclide with a long half-life, and it is one of the important radionuclides in a radioactive waste management. For the accurate liquid scintillation counter (LSC) analysis of a pure beta-emitting C-14, it should be separated from other beta emitters after extracted from the radioactive wastes since the LSC spectrum signals from C-14 overlaps with those from other beta-emitting nuclides in the extracted solutions. There have been three representative separation methods for the analysis of volatile C-14 such as acid digestion, wet oxidation, and pyrolysis. Each method has its own pros and cons. For example, the acid digestion method is easily accessible, but it involves the use of strong acids and generates large amount of secondary wastes. Moreover, it requires additional time-consuming purification steps and the skillful operators. In this study, more efficient and environment-friendly C-14 analysis method was suggested by adopting the photochemical reactions via in-situ decomposition using UV light source. As an initial step for the demonstration of the feasibility of the proposed method, instead of using radioactive C-14 standards, non-radioactive inorganic and organic standards were investigated to evaluate the recovery of carbon as a preliminary study. These standards were oxidized with chemical oxidants such as H2O2 or K2S2O8 under UV irradiations, and the generated CO2 was collected in Carbo-Sorb E solution. Recovery yield of carbon was measured based on the gravimetric method. As an advanced oxidation process, our photocatalytic oxidation will be promising as a time-saving method with less secondary wastes for the quantitative C-14 analysis in low-level radioactive wastes.
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