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        검색결과 25

        1.
        2023.05 구독 인증기관·개인회원 무료
        LILW disposal repository in Gyeongju, South Korea is considered with a concrete mixture that uses Ordinary Portland Cement (OPC) partially substituted with supplementary cementitious materials (SCMs). The degradation of cementitious materials that result from chemical and physical attacks is a major concern in the safety of radioactive waste disposal. We present a reactive transport model utilized as one of the geochemical simulation approaches for the timescales of concern that range from hundreds to thousands of years. The purpose of this study is to investigate the sensitivity of parameters in concrete disposal systems and to evaluate the influence of various assumptions on the chemical degradation of the systems using a reactive transport model. A reactive transport model in the concrete disposal vault was developed to evaluate the behavior of engineered barriers composed of cementitious materials. The sensitivity analysis was performed using reactive transport models through the coupling between COMSOL and PHREEQC. The databases selected for the analysis are the Thermochimie database presented by ANDRA. Among many variables considered, two variables that can highly affect chemical degradation were selected for detailed sensitivity analysis for dealing with uncertainties. This is important because the chemical degradation mechanism is generally sensitive to precipitation and diffusion coefficient. The first factor is precipitation, which might be the most important factor in chemical degradation because it acts as a calcium leaching of cementitious materials in a disposal system in a highly alkaline environment, increasing the porosity of the system. To predict the change in annual precipitation, the measurement of the precipitation observatory station in the nearest area of Gyeongju for the past 80 years was collected. The second factor is the diffusion coefficient, which plays an essential role in the durability of the concrete disposal system, promoting the decalcification of cementitious minerals, accelerating system degradation, and increasing the porosity of its system, thereby facilitating the migration of radionuclides. The diffusion coefficient values used in studies similar to this work were calculated and evaluated using the box-and-whisker method. The results of the sensitivity analyses for the reactive transport model in the concrete disposal system will be presented. The sensitivity cases show that the results obtained are much more sensitive to changes in transport parameters.
        3.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Airborne bacteria are expected to float in the mushroom cultivation house, as it is a special environment with high humidity and high temperatures. Their concentration and diversity in the indoor air of the cultivation house could effect the health of farmers and the quality of mushrooms. To examine whether microbiota of airborne bacteria change from year to year, we measured the indoor temperature, humidity, and airborne bacterial concentration from mushroom cultivation houses located in six regions in Korea from 2020 to 2021, and isolated and identified airborne bacteria. The surveyed data were compared and the bacterial diversity of the 1st year and the 2nd year were determined. Based on the average temperature and humidity data surveyed, it can be seen that the temperature and humidity environment in the cultivation houses is such that bacteria can easily reproduce. It was observed that the temperature inside the cultivation houses tends to be higher or lower depending on the season and correlates with the temperature outside the cultivation houses. In the first year survey, 32 species of 20 genera were identified, and in the second year survey, bacteria belonging to 29 species of 22 genera were identified. Among them, the most detected species were all species belonging to the genus Bacillus. There were only three species (Bacillus altitudinis, Brevibacterium frigoritolerans, and Staphylococcus epidermidis) that were continuously isolated in common. Our results showed that the species of floating bacteria greatly vary from year to year even for the same cultivation houses.
        4,000원
        4.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study was aimed to estimate the effect of ensiling period and bacterial inoculants on chemical compositions and fermentation characteristics on rye silage harvested at delayed stage. Rye (Secale cereale L.) was harvested after 20 days of heading stage (29.4% dry matter, DM). The harvested rye forage was applied with different inoculants following: applications of distilled water (CON), Lactobacillus brevis (LBB), Leuconostoc holzapfelii (LCH), or mixture of LBB and LCH at 1:1 ratio (MIX). Each forage was ensiled into 20 L mini bucket silo (5 kg) for 50 (E50D) and 100 (E100D) days in triplicates. The E50D silages had higher in vitro digestibilities of DM (IVDMD, p<0.001) and neutral detergent fiber (IVNDFD, p=0.013), and lactate (p=0.009), and acetate (p=0.011) than those of E100D, but lower pH, lactic acid bacteria (LAB), and yeast. By inoculant application, LCH had highest IVDMD and IVNDFD (p<0.05), while MIX had highest lactate and lowest pH (p<0.05). The CON and LCH in E50D had highest LAB and yeast (p<0.05), whereas LBB in E100D had lowest (p<0.05). Therefore, this study concluded that LCH application improved the nutrient digesbility (IVDMD and IVNDFD) of lignified rye silage, and longer ensiling period for 100 days enhanced the fermentation characteristics of silage compared to ensiling for 50 days.
        4,000원
        6.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to estimate the effect of different cutting lengths on fermentation characteristics and aerobic stability of whole crop rice (WCR) silage. The WCR was harvested at the yellow ripe stage (43.7%, DM), and then cut at 5 (R05), 10 (R10), and 20 cm (R20) of the theoretical length of cut with no cut WCR (R60). Each forage was ensiled into 20 L mini bucket silo (5 kg) for 150 days in quadruplicates. The cutting lengths were not affected the chemical compositions of WCR silage (p > 0.05). The pH (p < 0.001) and concentration of ammonia-N (p = 0.022) in WCR silage were increased linearly with the increase of cutting length. The concentration of lactate had quadratic effect (p = 0.007), which was highest in R20 silage (p < 0.05). The concentration of acetate was increased linearly (p = 0.014), but the concentration of butyrate was decreased linearly (p = 0.033). The lactic acid bacteria count was decreased linearly (p = 0.017), and yeast count had quadratic effect (p = 0.009), which was the highest in R20 silage (p < 0.05). Aerobic stability had strong quadratic effect (p < 0.001), which was the highest in R20 silage (p < 0.05). In conclusion, R60 silage had highest pH by a linear increase of ammonia-N concentration and led to low aerobic stability. While R20 silage had the lowest pH by high lactate concentration and led to high aerobic stability.
        4,000원
        7.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Human and material resource planning is one representative example of Operations Research. Resource planning is important not only in civilian settings but also in military ones. In the Air Force, flight scheduling is one of the primary issues that must be addressed by the personnel who are connected to flight missions. However, although the topic is of great importance, relatively few studies have attempted to resolve the problem on a scientific basis. Each flight squadron has its own scheduling officers who manually draw up the flight schedules each day. While mistakes may not occur while drafting schedules, officers may experience difficulties in systematically adjusting to them. To increase efficiency in this context, this study proposes a mathematical model based on a binary variable. This model automatically drafts flight schedules considering pilot’s mission efficiency. Furthermore, it also recommends that schedules be drawn up monthly and updated weekly, rather than being drafted from scratch each day. This will enable easier control when taking the various relevant factors into account. The model incorporates several parameters, such as matching of the main pilots and co-pilots, turn around time, availability of pilots and aircraft, monthly requirements of each flight mission, and maximum/minimum number of sorties that would be flown per week. The optimal solution to this model demonstrated an average improvement of nearly 47% compared with other feasible solutions.
        4,000원
        10.
        2019.04 구독 인증기관·개인회원 무료
        In this study, we developed ten microsatellite markers specific to L. angelina using the Illumina NextSeq 500 platform. Forty-three individuals of L. angelina collected from three localities in South Korea were genotyped to validate these markers and to preliminarily assess population genetic characteristics. The observed number of alleles, observed heterozygosity (HO), and expected heterozygosity (HE) at a locus ranged from 4–13, 0.211–0.950, and 0.659–0.871 in the population with the largest sample size (20 individuals), respectively, thereby validating the suitability of the markers for population analyses. Our preliminarily assessment of the population genetic characteristics indicates the presence of inbreeding in all populations, an isolation of the most geographically distant population (Seocheon), and lower HO than HE. The microsatellite markers developed in this study will be useful for studying the population genetics of L. angelina collected from additional sites in South Korea and from other regions. †These authors contributed equally to this paper.
        11.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objectives of this study was to evaluate the degradability and digestibility of crude protein (CP), rumen undegradable protein (RUP), and individual amino acids (AA) on six by-product feedstuffs (BPF) (rice bran, RB; wheat bran, WB; corn gluten feed, CGF; tofu residue, TR; spent mushroom substrate from Pleurotus ostreatus, SMSP; brewers grain, BG) as ruminants feed. Three Hanwoo steers (40 months old, 520 ± 20.20 kg of body weight) fitted with a permanent rumen cannula and T-shaped duodenal cannula were used to examine of the BPF using in situ nylon bag and mobile bag technique. The bran CGF (19.2%) and food-processing residue BG (19.7%) had the highest CP contents than other feeds. The RUP value of bran RB (39.7%) and food-processing residues SMSP (81.1%) were higher than other feeds. The intestinal digestion of CP was higher in bran RB (44.2%) and food-processing residues BG (40.5%) than other feeds. In addition, intestinal digestion of Met was higher in bran RB (55.7%) and food-processing residues BG (44.0%) than other feeds. Overall, these results suggest that RB and BG might be useful as main raw ingredients in feed for ruminants. Our results can be used as baseline data for ruminant ration formulation.
        4,000원
        12.
        2018.05 구독 인증기관·개인회원 무료
        In the United States and Europe, new environmentally friendly asphalt pavement has been researched as an alternative to traditional hot asphalt pavement. After the Paris Convention of 2015, policies should be found to reduce carbon dioxide. In the field of asphalt pavement, new methods are needed to reduce carbon dioxide from the traditional hot asphalt pavement. In Korea, waste asphalt is growing and natural aggregate is running dry. So the government is implementing policies to increase the use of waste resources. So, it created a new asphalt pavement method to reduce CO2 and use waste asphalt. It is a cold recycled asphalt pavement. Emulsified asphalt has a balance of dispersibility, stability, and adhesive between water, aggregates, and asphalt. But, the physical properties of emulsified asphalt can be degraded compared to traditional hot asphalt pavement. So there are limitations in actual use. The study compared the softening point, elastic recovery, and penetration properties of asphalt mix compounds by using latex in emulsified asphalt. In particular, cations latex was used for the emulsified asphalt, which could further improve the physical properties.
        13.
        2018.04 구독 인증기관·개인회원 무료
        The effects of cold storage temperature and exposure duration on immature stages of spotted-wing drosophila (SWD) Drosophila suzukii (Diptera: Drosophilidae) on ‘Campbell Early’ grapes were examined to establish a phytosanitary control method. The immature stages (eggs, larvae and pupae) of SWD were all dead after a 6-day cold treatment at 1°C and 8-day cold treatment at 1.5 and 2°C. Small-scale tests using pupae, which were the most-cold tolerant stage, confirmed the validity of the selected temperature and exposure durations. Conversely, the 8- and 10-day at 1°C treatments showed 100% mortality, suggesting that these treatments can guarantee quarantine security against infestations of SWD on exported ‘Campbell Early’ grapes.
        14.
        2016.10 구독 인증기관·개인회원 무료
        The number of reported mitochondrial genomes (mitogenomes) from the monotypic Lasiocampoidea has been limited until recently. In this study, we sequenced the complete mitogenome of the lappet moth, Kunugia undans (Lepidoptera: Lasiocampidae), and compared it to those of other lasiocampid species and macroheteroceran superfamilies (59 species in six superfamilies). The 15,570-bp long K. undans genome had the typical set of genes found in animal mitogenomes, with the exception of one additional trnR that are located between trnA and trnN loci. Considering that the two trnR copies are located in tandem with proper secondary structures and identical anticodons, a gene duplication event might be responsible for the presence of the two tRNAs. In summary, the general mitogenome characteristics of Lasiocampoidea did not differ greatly from the remaining macroheteroceran superfamilies, but it did exhibit some unique features.
        15.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The mechanical properties and microstructures of Aluminum 6056 alloys were investigated for their use in the fabrication of a piton block. The EN-AW6056 alloys exhibited a tensile strength of 375 MPa for a solution treatment temperature of 550 oC for 2 h followed by an aging treatment at 190 oC for 4 h. The microstructures of the heat treated specimen showed that the Mg2Si phase with a size of 3~5 um was dispersed throughout the aluminum matrix when the heat treatment was done. Moreover, in order to identify the forgeability of the specimen, upsetting tests were done. For up to 80 % of the upsetting ratio, the specimen maintained its original shape, and at above 80 % of the upsetting ratio, the specimen underwent crack development. The specimen was successfully forged without any defects with the examined material conditions. The material conditions together with the forging conditions are discussed in terms of the microstructures and mechanical properties.
        4,000원
        16.
        2015.10 구독 인증기관·개인회원 무료
        The spotted-wing drosophila (SWD), Drosophila suzukii (Diptera: Drosophilidae), originally distributed across a few Asian countries, including South Korea, has invaded North America and Europe, but is absent from Australia. In order to export the South Korean grape cultivar Campbell Early to Australia, its potential to serve as oviposition and development medium for SWD must first be determined. In this study, we determined the oviposition and development potential of SWD on Campbell Early, after elucidating the SWD life cycle and establishing an artificial diet-based mass-culturing system. An investigation of the life cycle under five temperature regimes (16, 19, 22, 25, and 28°C) showed that the durations of the egg, larval, and adult stages were shorten when temperature was increased from 16, 19, 22, 25, and 28°C, but pupal duration was shortest at 25°C and extended again at 28°C. A test of oviposition and development potential of SWD on Campbell Early grape clusters showed oviposition of 30.8 ± 6.8 eggs per cluster of injured grapes and 157.7 ± 16.2 eggs on a culture dish of artificial diet. However, in a similar experiment using uninjured grape clusters, only a single egg was deposited on the grape skin, which soon dried. In light of these results, newly harvested grapes left at vineyards during daily harvests are unlikely to serve as an oviposition and development medium for SWD, as long as the grapes remain uninjured.
        17.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to investigate the association between carotid artery calcification (CAC) on panoramic radiograph and intima-media thickeness (IMT) measured on ultrasound. Panoramic radiographs which were taken from dental patients aged 50 years and older who visited for dental treatment were screened for the presence of CAC. The study group was composed of seven patients (four males and three females, average age 74.4±4.2 yrs) with CAC detected on panoramic radiographs, and the control group eleven patients (seven males and four females, average age 64.5±10.1 yrs) without CAC. All the patients underwent carotid ultrasonography to measure carotid IMT. The IMT was compared between the groups by nonparametric analysis of covariance (ANCOVA). The range of IMT of the study group was 1.10~2.0 mm, while that of the control group 0.60~1.10 mm. The mean of IMT was 1.50±0.34 mm in the study group and 0.85±0.14 mm in the control group, and there was statistically significant difference between the two groups (p<.01). In conclusion, CAC detected on panoramic radiograph might have an association with atherosclerosis
        4,000원
        19.
        2012.03 구독 인증기관 무료, 개인회원 유료
        Experiments were conducted in order to assess the healing effect of bee venom (BV) cream on full-thickness skin wounds in rabbits. BV cream was compared with silver sulfadiazine (SS) as a topical medicament against a control on experimentally created full-thickness wounds. Two wounds measuring 2 × 2 cm were created bilaterally (four wounds/rabbit) on the dorsolateral aspect of the trunk of seven New Zealand white rabbits. Wound treatments were evenly distributed on four sites, using a Latin square design. The contact layer of wounds was treated with physiological saline (control), SS cream, and BV cream over a period of 28 days. Assessment of wound healing was based on scab hardness, wound exudates, wound area, unepithelialized granulation tissue, and histopathological findings. Topical application of BV and SS creams to wounds resulted in reduced inflammation, debridement of necrotic tissue, and promoted granulation and epithelialization. Wound healing was faster, with statistical significance in BV and SS treatments, compared to the control (P<0.05). Treatment with BV evoked an anti-inflammation effect in a rabbit model. BV cream produced a wound healing effect similar to that of commercially available SS cream. Anti-inflammation effect as a topical treatment with BV cream appears to be better than that with SS cream. These results suggest that topical application of BV cream may be an alternative treatment for full-thickness skin wounds.
        4,000원
        20.
        2010.12 구독 인증기관 무료, 개인회원 유료
        A nine-month-old male Pekingese weighing 5.7 kg was admitted to the Veterinary Medical Center at Chungbuk National University with a history of acute nonambulatory tetraparesis after minor trauma. A diagnosis of atlantoaxial instability with a dens axis fracture was based on examination of survey spinal radiographs and was confirmed during surgery. A modified ventral fixation technique using cortical screws was used for stabilization of the atlantoaxial joint. Serial evaluation based on radiographic and neurologic assessment was performed eight weeks after surgery. Symptoms of tetraparesis disappeared gradually, and arthrodesis of the atlantoaxial joint using a ventral fixation technique has maintained stable fixation.
        4,000원
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