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        검색결과 862

        21.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Roridin E, a constituent of Podostroma cornu-damae, has excellent medicinal properties and exhibits powerful anticancer effects. However, being a poisonous mushroom, P. cornu-damae is difficult to find in its natural environment. Therefore, only a limited amount of roridin E is isolated from P. cornu-damae. We isolated roridin E from mycelial culture medium of P. cornu-damae and examined its effects on five breast cancer cell lines. The purity of the isolated roridin E was 96%. It exhibited anticancer effects on all five breast cancer cell lines, with an IC50 of at least 0.0006 mg/L. To the best of our knowledge, this is the first report on the investigation of effects of roridin E isolated from the mycelium of P. cornu-damae mushrooms on five breast cancer cell lines. However, safety issues should be investigated and addressed in future studies before roridin E is used in clinical settings.
        4,000원
        22.
        2023.05 구독 인증기관·개인회원 무료
        Nuclear weapon generates huge amount of radioactive fallout which is extremely dangerous. The fallout gradually falls to the ground and then covers every surface in city and nature. A hydrogel decontamination medium has been developed to clean the surface polluted by the fallout. The hydrogel is soluble in water so the used hydrogel can be simply removed from the surface by washing. However, significant amount of waste water, containing the radioactive fallout, is generated with this process. In this respect, it is necessary to secure alternative technical options for the used hydrogel recovery. In this study, a steam-suction process was suggested for the used hydrogel recovery. Contaminated stainless steel surface, with fixed simulated fallout particles, was prepared for test. The simulated fallout particles were obtained by high-temperature treatment of a mixture of natural soil, used concrete, and Fe2O3. The hydrogel, composed of poly-vinyl alcohol and borax, was spread onto the contaminated stainless steel surface. The hydrogel was soft at first and it gradually becomes rigid with time. The used hydrogel was recovered by suction with a simultaneous steam spraying to soften the rigid gel. As a result, the clean surface of the stainless steel without the simulated fallout particles was obtained, showing the feasibility of this technique for the used hydrogel recovery.
        23.
        2023.05 구독 인증기관·개인회원 무료
        When the recycling technology of spent nuclear fuels (SNF) for future nuclear reactor systems and the treatment technology of SNF for disposing of in a disposal site use a molten salt such as LiCl-KCl eutectic as a processing medium one of the essential unit processes is a distillation process that remove the salt component mixed with fission products recovered. Especially, in case of Pyro-SFR recycling system the recovered nuclear fuel materials such as U, TRU and some of rare earths come from main three processes (electro-refining, electro-winning, and drawdown processes) for recycling of SNF. These recovered fuel materials contain large portion of molten salt or liquid cadmium which requires removal of them by distillation. In spent nuclear fuels discharged from PWR the portion of composing element is as follows. Uranium is about 95%, other actinides such as transuranic elements (TRU; Np, Pu, Am, Cm) is about 1%, the rare earths (lanthanides) is about 1%, and the other elements is about 3%. For example, americium (Am) in the recovered fuel materials has a problem that the reported loss of Am inevitably occurs during the vacuum salt distillation operation. A new segregation method of AMM (actinide metal mixture)–salt system is based on the difference in melting point of the actinide elements. It is possible to apply this segregation method to recovering other actinides from AMM with accompanied salt because of relatively large amount and lower melting point of a specific element in other actinides avoiding vacuum salt distillation. This new segregation method successfully tested using a surrogate element such as aluminum due to its similar melting point with a specific element. The segregation principle is solid-liquid separation, thus the solidified actinides mixture ingot can take out of a molten salt medium.
        24.
        2023.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aims to present a method to evaluate the relative risk of failure due to liquefaction of domestic small to medium-sized earthfill dams with a height of less than 15 m, which has little information on geotechnical properties. Based on the results of previous researches, a series of methods and procedures for estimating the probability of dam failure due to liquefaction, which calculates the probability of liquefaction occurrence of the dam body, the amount of settlement at the dam crest according to the estimation of the residual strength of the dam after liquefaction, the overtopping depth determined from the amount of settlement at the dam crest, and the probability of failure of the dam due to overtopping was explicitly presented. To this end, representative properties essential for estimating the probability of failure due to the liquefaction of small to medium-sized earthfill dams were presented. Since it is almost impossible to directly determine these representative properties for each of the target dams because it is almost impossible to obtain geotechnical property information, they were estimated and determined from the results of field and laboratory tests conducted on existing small to medium-sized earthfill dams in previous researches. The method and procedure presented in this study were applied to 12 earthfill dams on a trial basis, and the liquefaction failure probability was calculated. The analysis of the calculation results confirmed that the representative properties were reasonable and that the overall evaluation procedure and method were effective.
        4,000원
        29.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For practical applications of graphene sheets in a variety of fields, mass production of high-quality graphene sheets is necessary. Herein, we reported a cost-effective, green, and simple approach to synthesizing mass production exfoliated graphene (EG) flakes employing electrochemical exfoliation of pencil graphite in neutral aqueous electrolytes. Pencil graphite cores of different grades were applied as anode and cathode electrodes and exposed to the electrolyte solution at a different voltage. Several parameters were examined and optimized, including pencil grade (2,4,6,8 B), applied voltage (10, 15, 20, 30 V), different inorganic electrolytes ((NH4)2SO4, Na2SO4, NaNO3, NaCl, and CH3COONa), and the concentration of electrolytes. The optimal condition was chosen by considering the mass of produced graphene and the conductivity of the graphene solution. The optimal conditions were as follow: pencil grade: 6B; applied voltage: 10 V; electrolyte type: Na2SO4; electrolyte concentration: 0.1 M. Under these conditions, the production yield was > 95% within 3 h and 9 min. The EG was characterized by utilizing FT-IR, XRD, Raman spectroscopy, FE-SEM, Cyclic Voltammetry, and Electrochemical Impedance Spectroscopy (EIS). Characterization indicates that the synthesized EG had an XRD peak at 2θ = 26.6° and an ID/ IG ratio of 0.36. Furthermore, the EG showed good conductivity when tested by cyclic voltammetry and EIS whereas the R2 values were 985.8 and 76.3 Ω for bare GCE and EG/GCE, respectively. In addition, EG effectively removed cadmium (Cd(II)) with an adsorption level of 8.72 mg/g. The results from this study suggest that EG can be scaled up and commercialized in an environmentally friendly and low-cost manner, especially in low-income countries, and using it to rectify metal ions.
        4,200원
        30.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 중소병원간호사가 급격하게 변화하는 의료환경에 유연하게 대처할 수 있도록 업무 스트레스 및 회복탄력성, 간호업무성과를 파악하고 영향요인을 확인하기 위한 서술적 조사연구이다. 연구 대상자는 S지역에 소재하는 4개 중소병원에서 근무하는 간호사 219명이었으며, 구조화된 설문지를 이용하 여 조사하였다. 수집된 자료는 기술통계, t-test, ANOVA, Pearson’s 상관관계 분석 및 다중회귀분석을 이 용하여 분석하였다. 중소병원 간호사의 업무 스트레스와 간호업무성과는 음의 상관관계(r=-0.150, p<.05), 업무 스트레스와 회복탄력성은 양의 상관관계(r=0.160, p<.05). 간호업무성과는 회복탄력성과 양의 상관관 계를 보였다(r=0.351, p<.01). 간호업무성과에 영향을 미치는 변수는 회복탄력성(β=.231, p<.01)이였으며, 설명력은 17.4%로 나타났다(Adj.R2=0.174, p<.001). 따라서 간호사의 간호업무성과를 향상시키기 위해서 는 회복탄력성을 증가시킬 필요가 있으며, 이를 위해서는 간호사 개인의 역량에 맞는 다양한 교육 프로그 램을 개발하여 적용할 필요가 있겠다.
        4,600원
        31.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As the 4th industrial revolution emerges, the implementation of smart factories are essential in the manufacturing industry. However, 80% of small and medium-sized enterprises that have introduced smart factories remain at the basic level. In addition, in root industries such as injection molding, PLC and HMI software are used to implement functions that simply show operation data aggregated by facilities in real time. This has limitations for managers to make decisions related to product production other than viewing data. This study presents a method for upgrading the level of smart factories to suit the reality of small and medium-sized enterprises. By monitoring the data collected from the facility, it is possible to determine whether there is an abnormal situation by proposing an appropriate algorithm for meaningful decision-making, and an alarm sounds when the process is out of control. In this study, the function of HMI has been expanded to check the failure frequency rate, facility time operation rate, average time between failures, and average time between failures based on facility operation signals. For the injection molding industry, an HMI prototype including the extended function proposed in this study was implemented. This is expected to provide a foundation for SMEs that do not have sufficient IT capabilities to advance to the middle level of smart factories without making large investments.
        4,000원
        32.
        2022.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper examined the effects of online English-medium instruction (EMI) on high school students’ performing English face threatening speech acts, by assessing indirect expressions and token agreement (agreement plus but). Participants completed an English placement test and English pretest and posttest through a Google survey. English proficiency, required for study participation was measured using the English placement test. An English pretest and posttest measured English pragmatic performance. The students were given approximately four weeks to complete eight online lectures. The experimental group completed eight online lectures which taught five face threatening speech acts, based on formal situations in the United States. The control group completed eight online lectures about worldwide cultures. The experimental group showed a significant improvement in the English posttest compared with the control group, based on improvements observed in the use of indirect expressions and token agreement. A difference between groups using indirect expressions was observed in an unfamiliar person scenario but not in a familiar person scenario.
        6,400원
        33.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to replace the imported Chinese complete medium for Lentinula edodes with a newly-developed complete medium that is suitable for export as well. Three media compositions that supported fast mycelium growth and higher density, compared to that in the control, were chosen. Culture in the T13 medium reduced the incubation period for ‘Nongjingo’ by 12 days and for ‘Cham-aram’ by 10 days, compared to that required for the control; in addition, the number of days required for browning was greatly reduced for both varieties. The quantity of each mixed medium was increased according to the composition from the 1st to the 5th cycle by 5.9% for ‘Nongjingo’ and 12.6% for ‘Cham-aram’ in T13, compared to that in the control. A mixed medium comprising oak sawdust + Douglas fir sawdust + corn flour (40:40:20, v/v) was selected as the most suitable complete medium.
        4,000원
        34.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The home hydroponic system used in this experiment supplied the nutrient solution using the ebb and flow-type system, and the supply time, interval, and water levels of the nutrient solutions were fixed. This experiment was conducted to find a more favorable growth medium for plant growth in the hydroponic system. The medium used in the experiment was of two types, phenolic foam and rockwool, and the heights were 28 and 38 mm, respectively. As for the the multipurpose nutrient solutions (GNU1 and GNU2) were prepared in the lab. The composition of the GNU1 and GNU2 was the same, and there was a difference between 100 and 70% in ion concentrations. The plants used were Ssamchoo (Brassica lee ssp. namai) and Romaine lettuce (Lactuca sativa L. var. longiflora). First, in the physicochemical measurements of the empty medium, change in the pH and EC of the distilled water passing through the medium was less in the rockwool than in the phenolic foam. This indicates that there is less change in the chemical properties of the nutrient solution due to the medium when rockwool is used. After hydroponic culture of Ssamchoo and Romaine lettuce, the medium showed more residual salts in Romaine lettuce. Both Ssamchoo and Romaine lettuce showed less salt accumulation in rockwool. The emergence rate was significantly higher in rockwool for both species. The lower height of the medium, the faster the emergence was. Ssamchoo displayed significantly higher fresh weight (124.7%), shoot length (107.6%), and leaf width (107.9%) when grown in GNU1, but there were no significant differences as affected by the medium. However, in Romaine lettuce, the type and height of the medium resulted in significant differences. The fresh weight of Romaine lettuce was significantly higher in rockwool (119.6%) than in phenolic foam, and significantly higher at 38 (114.6%) than 28 mm. Although there is a difference depending on the species, rockwool is more suitable for the ebb and flow-type system than phenolic foam, and the height of 38 is more advantageous than 28 mm.
        4,200원
        36.
        2022.10 구독 인증기관·개인회원 무료
        Organic waste generated by small and medium-sized (S&M-sized) metal decontamination in NPP decommissioning. To lower the concentration of these organic substances for a level acceptable at the disposal site, the project of “Development of Treatment Process of Organic Decontamination Liquid Wastes from Decommissioning of Nuclear Power Plants” is being carried out. The conditioning and treatment process of organic liquid waste was designed. Also, the literature was investigated to make simulated organic liquid waste, and the composition of these waste was analyzed and compared. As the decontamination agent, organic acids such as EDTA, oxalic acid, citric acid are used. The sum of the concentrations of these organic materials was set to a maximum value of 1,000 ppm. The major metal ions of the decontamination liquid waste estimated are 59Fe, 51Cr, 54Mn, 63Ni, and the concentrations are respectively 527, 163, 161, 159 ppm. Additional major metal ions are 60Co, 58Co, 137Cs. 58Co is replaced by 60Co because it has the same chemical properties as 60Co. Unlike the HLW, the contamination level of S&M-sized metal in primary system was quite low, so 60Co is set to 2,000 Bq/g. Considering the contribution of fission and gamma ray dose constant, 137Cs was estimated to 360 Bq/g. Also, suspended solids of decontamination liquid waste were set at 500 ppm. Under these assumptions, the simulated organic liquid waste was made, and then organic substances and metal ions were analyzed with TOC analyzer and ICP-OES. The TOC analysis value was expected to 392 ppm in consideration of the equivalent organic quantity. the test result was 302 ppm. Some of organics appears to have been decomposed by acid. The values of metal ions (Fe3+, Cr3+, Mn2+, Ni2+) analyzed by ICP-OES are 139, 4, 152, 158 ppm, respectively. A large amount of Cr3+ and Fe3+ were expected to exist as ions, but they existed in the form of suspended solid. Mn2+ and Ni2+ came out similar to the expected values. The designed conditioning and treatment process is largely divided into pretreatment, conditioning, and decomposition processes. After collecting in the primary liquid waste storage tank, large particulate impurities and suspensions are removed through a pretreatment process. In the conditioning process, treated liquid waste passes through UF/RO membrane system, and pure water is discharged to the environment after monitoring. Concentrated water is decomposed in the electrochemical catalyst decomposition process, then this water secondarily passes through the RO membrane system and then discharged to the environment after monitoring. Through an additional experiment, the conditioning and treatment process will be verified.
        39.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to suggest a plan to improve the level of acceptance of related technologies and the transition to smart factories of small and medium-sized manufacturing enterprises by using ‘technology readiness’ and ‘integrated technology acceptance model’. To this end, the research hypothesis was verified by collecting questionnaire data from 130 small and medium- sized manufacturing companies in Korea and conducting path analysis. First, optimism affects performance expectations, social influence, and facilitation conditions, innovation affects performance expectations, effort expectations, and social influence, discomfort affects performance expectations, social influence, and facilitation conditions, and anxiety affects effort expectations, social influence and facilitation conditions. has been proven to affect Finally, performance expectations, effort expectations, social influence, and facilitation conditions were verified to have a significant positive effect on the intention to accept technology.
        5,100원
        40.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the growth and antioxidant activity of Pleurotus ostreatus mycelia grown in medium supplemented with Aronia. The diameter and dry weight of the mycelia were increased in the medium supplemented with Aronia compared with the untreated medium. The total polyphenol content of mycelia grown in medium supplemented with Aronia and untreated medium was 6.54 mg GAE/g and 5.77 mg GAE/g, respectively. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of mycelia grown in medium supplemented with Aronia and untreated medium was 61.81% and 49.65%, respectively. Moreover, the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity of mycelia grown in medium supplemented with Aronia and untreated medium was 59.83% and 52.66%, respectively. These results confirmed that P. ostreatus mycelial growth and antioxidant activity were increased when Aronia was added to the culture medium.
        4,000원
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