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        검색결과 371

        41.
        2022.05 구독 인증기관·개인회원 무료
        Polyoxometalates (POMs) are nanoclusters composed of transition metals with high oxidation states. Owing to their redox properties and structural diversity, POMs have been applied to broad fields, such as catalysis, materials, and medicine. Among various fields of application, POMs play an important role in radiochemistry. POMs can form complexes with tri- and tetravalent lanthanides and actinides (radioactive elements), which may be good sequestrators or agents for separating nuclear wastes. Among the most prominent POM structures, Anderson-type POMs with a general formula of [Hy(XO6)M6O18]n− (y=0–6, n=2–8, M=addenda atom, X=heteroatom) represent one of the basic topological structures of the POM family. An important feature of Anderson type POMs is incorporating a large number of various heteroatoms with different size and oxidation states, which can lead to tune chemical properties. Interestingly, no example of Anderson type POMs with early transition metal ions in the heteroatom site has been reported to date. Herein, we discovered that the Anderson POM Na2K6Ti0.92W6.08O24·12H2O, which consists of pure inorganic framework built from a central Ti core supported by six WO6 inorganic scaffold, and the crystal structure was confirmed and refined using single-crystal X-ray diffraction (SC-XRD). In addition, structural characterizations, including, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Inductively coupled plasma-optical emission spectroscopy (ICP-OES) were performed.
        42.
        2022.05 구독 인증기관·개인회원 무료
        Efficient capture and storage of radioactive iodine (consisting of two isotopes: 129I and 131I), produced or released from nuclear activities, are of paramount importance for sustainable development of nuclear energy due to their volatility and long half-life. Therefore, it is very important to develop new adsorbents for efficient utilization of radioactive iodine from nuclear waste. Various methods and materials are used for I2 capturing and removing, including MOFs due to their high porosity and fast adsorption kinetics, which are rightfully considered effective sorbents for removing I2. Metal–organic frameworks (MOFs) are porous crystalline materials which have diverse pore geometry and unique physicochemical properties, have attracted enormous attention for use in gas storage, separation and catalysis. The ability of MOFs to adsorb volatile products at room temperature can significantly improve the cost-effectiveness of the utilization process. This work describes the synthesis and characterization of three new metal-organic frameworks based on pyrazine (pyz), 44’bipyridine (bpy), 1,2 -bis(4 - pyridyl) – ethane (bpe) and copper (II) hexafluorozironate, as potential adsorbents for I2 capture. All of these three MOFs exhibit a two - dimensional (2D) crystal structure consisting from infinity non-crossing linear chains. The crystal structure of [Cu(pyz)2(ZrF6)2(H2O)2], [Cu(bpy)4(H2O)2ZrF6] and [Cu(bpe)4(H2O)2ZrF6] were characterized using powder X-ray diffraction (PXRD), single crystal X-ray diffraction (SC-XRD). Comparative characteristics of synthesized MOFs, including Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were also performed. The I2 sorption experiments were examined by UV-vis spectroscopy.
        43.
        2022.05 구독 인증기관·개인회원 무료
        Some Spent Fuel Pools (SFPs) will be full of Spent Nuclear Fuels (SNFs) within several years. Because of this reason, transporting the SNF from SFP to interim storage facilities or permanent disposal facilities should be considered. There are two ways to transport the SNF from a site to other site, one is the land transportation with truck or train, and the other is the maritime transportation with ship. The maritime transportation has some advantages compared with the land transportation. The maritime transportation method uses safer route which is far from populated area than land transportation method, and transport more weight than land transportation method. However, the cask should be loaded into the ship for the maritime transportation, and there is a possibility of a drop accident of the cask onto the ship. Therefore, it is necessary to evaluate the structural integrity of the cask and ship for the drop accident during the loading process. To evaluate the structural integrity of the cask and ship, it is necessary to determine the analysis conditions that caused the greatest damage in the drop accident. There may be various conditions such as the drop angle of the cask, the initial falling speed, the drop position onto the ship, the size of the ship, etc. This study set the drop angle of the cask and the drop position onto the ship as the simulation variables, which have high possibility to occur during cask drop. However, the others are excluded since they are controllable by worker. In this paper, various drop angle (0, 15, 30, 45, and 70 degree) of the cask were simulated to define the greatest damage condition. KORAD-21 cask model was used for Finite Element Analysis (FEA), and FEA was performed to simulate a horizontal drop (1 m drop). The strain-hardening material properties for the deck were used as HT36 steel. The Cowper-Symonds constitutive model for HT36 was used to consider the strain rate effect. A Tie-down structure for supporting the cask was modeled with the cask model which contained inner structures like canister, basket, etc. Structural integrity of the cask and tie-down structure were evaluated using the von-Mises stress and equivalent plastic strain (PEEQ), and one of the ship deck was evaluated using deflection of ship deck and equivalent plastic strain. Compared with each cask drop angle conditions, 45 degree of the cask drop angle showed the highest deflection and PEEQ values, but did not exceed ultimate strain of HT36. In the ship deck, the corner of deck showed the highest PEEQ value in all simulation cases. As the result, the 45 degree of the cask drop angle condition results was more conservative than other conditions, and the corners of deck failure was able to evaluate ship safety.
        52.
        2021.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present an updated version of the multilayer spectral inversion (MLSI) recently proposed as a technique to infer the physical parameters of plasmas in the solar chromosphere from a strong absorption line. In the original MLSI, the absorption pro le was constant over each layer of the chromosphere, whereas the source function was allowed to vary with optical depth. In our updated MLSI, the absorption pro le is allowed to vary with optical depth in each layer and kept continuous at the interface of two adjacent layers. We also propose a new set of physical requirements for the parameters useful in the constrained model tting. We apply this updated MLSI to two sets of Hα and Ca ii line spectral data taken by the Fast Imaging Solar Spectrograph (FISS) from a quiet region and an active region, respectively. We nd that the new version of the MLSI satisfactorily ts most of the observed line pro les of various features, including a network feature, an internetwork feature, a mottle feature in a quiet region, and a plage feature, a superpenumbral bril, an umbral feature, and a fast down ow feature in an active region. The MLSI can also yield physically reasonable estimates of hydrogen temperature and nonthermal speed as well as Doppler velocities at different atmospheric levels. We conclude that the MLSI is a very useful tool to analyze the Hα line and the Ca ii 8542 line spectral daya, and will promote the investigation of physical processes occurring in the solar photosphere and chromosphere.
        5,100원
        55.
        2021.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The overestimation and underestimation of the radioactivity concentration of difficult-to-measure radionuclides can occur during the implementation of the scaling factor (SF) method because of the uncertainties associated with sampling, radiochemical analysis, and application of SFs. Strict regulations ensure that the SF method as an indirect method does not underestimate the radioactivity of nuclear wastes; however, there are no clear regulatory guidelines regarding the overestimation. This has been leading to the misuse of the SF methodology by stakeholders such as waste disposal licensees and regulatory bodies. Previous studies have reported instances of overestimation in statistical implementation of the SF methodology. The analysis of the two most popular linear models of the SF methodology showed that severe overestimation may occur and radioactivity concentration data must be dealt with care. Since one major source of overestimation is the use of minimum detectable activity (MDA) values as true activity values, a comparative study of instrumental techniques that could reduce the MDAs was also conducted. Thermal ionization mass spectrometry was recommended as a suitable candidate for the trace level analysis of long-lived beta-emitters such as iodine-129. Additionally, the current status of the United States and Korea was reviewed from the perspective of overestimation.
        5,500원
        56.
        2021.09 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        Naturally occurring left ventricular hyperplasia is a rare but lethal disease. There are very few reports of this cardiac disease in captive nonhuman primates. In a colony of Macaca mulatta (Rhesus monkey) at California National Primate Research Center, a large number of rhesus macaques were diagnosed by autopsy with naturally occurring left ventricular hypertrophy without obvious underlying diseases over a 22-year period. The confirmatory diagnosis of ventricular hypertrophy was based on findings of notable left ventricular concentric hypertrophy with reduced left ventricular lumen, which is very similar to human ventricular hypertrophy cases. This report discusses an 11-year-old Macaca fascicularis monkey (Cynomolgus monkey, crab-eating macaque), weighing 2.95 kg, that was presented for enrollment in a pharmacokinetic (PK) study. During the PK experiment, the monkey died following a sudden decrease in percutaneous oxygen saturation and heart rate. Gross and histological examinations of the heart were performed. On gross pathology, the left ventricular wall was thickened, and the chamber lumen was reduced. In histopathological examination using hematoxylin- eosin and Masson-trichrome stains, fibrosis and myocyte disarray were not observed, but an increased cell density, compared to the normal heart, was confirmed. The autopsy results confirmed left ventricular hyperplasia as the major cause of death.
        4,000원
        57.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of the study is to assess morphological and chromosomal comparison of Mini type Phalanopsis ‘KS Little Gem’ and four domestic market available cultivars (‘Queen Beer’, ‘Tony Pink’, ‘Vaviche’ and ‘Rorens’). ‘KS Little Gem’ had the highest number of leaves (14.9), while the other four types had fewer than ten. The longest leaf length was 21.5㎝ for ‘Tony Pink’, followed by 16.2㎝, 18.0㎝ and 17.5㎝ for ‘Queen Beer’, ‘Rorens’ and ‘Vaviche’ respectively. The length and width of the petals of ‘KS Little Gem’ were 29.5㎜ and 25.6㎜ respectively indicating a round shape flower compared to other cultivars. When the flower lifespan of ‘KS Little Gem’ was compared to four cultivars of the domestic market, it was found that it had a 123-day shelf life, which was twice longer than that of the four cultivars. According to chromosome analysis ‘KS Little Gem’, ‘Rorens’, ‘Tony Pink,' and ‘Vaviche’ were tetraploid (2n = 4x = 76) while ‘Queen Beer’ was diploid (2n = 2x = 38). The estimated DNA content of ‘KS Little Gem’, ‘Rorens’, ‘Tony Pink’ and ‘Vaviche’ had 4918.4, 4794.2, 4705.2 and 4964.3 Mbp respectively, which were roughly double than that of P. cornu-cervi (control, 2n = 2x = 38). However, ‘Queen Beer’, had an estimated DNA content of 2802.2Mbp, similar to that of P. cornu-cervi. The morphological features, genome size and chromosomal data reported in these studies can be used by breeders to create more efficient Phalaenopsis breeding programs.
        4,000원
        58.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Phalaenopsis ‘KS Little Gem’ is a new cultivar with superior ornamental qualities. Newly produced cultivars are often studied to determine the optimum growing conditions, as production management practices vary within species. We focused on the effects of temperature and fertilizer application on the growth and carbohydrate content of ‘KS Little Gem’ plantlets. Two-month-old plantlets were subjected to different temperatures (20, 25, and 30°C) and fertilizer rates (0.33, 0.5, and 1 g・L-1) inside a growth chamber. Data were collected from leaves and roots regarding their growth, fresh weight, sugar content, and starch content. The results revealed that temperature significantly affected leaves and roots parameters, fresh weight, and carbohydrate content of the plantlets. However, fertilizer rates alone showed no significant effects on the growth and carbohydrate content of plantlets. The highest leaf and root growth, root fresh weight, and leaf carbohydrate content were observed in plantlets subjected to 25°C. In addition, ‘KS Little Gem’ plants grown under 30°C had significantly inhibited growth and reduced carbohydrate content in both the leaves and roots.
        4,000원
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