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        검색결과 11

        1.
        2022.10 구독 인증기관·개인회원 무료
        Decommissioning waste is generated at all stages during the decommissioning of nuclear facilities, and various types of radioactive waste are generated in large quantities within a short period. Concrete is a major building material for nuclear facilities. It is mixed with aggregate, sand, and cement with water by the relevant mixing ratio and dried for a certain period. Currently, the proposed treatment method for volume reduction of radioactive concrete waste was involved thermomechanical and chemical treatment sequentially. The aggregate as non-radioactive materials is separated from cement components as contaminated sources of radionuclides. However, to commercialize the process established in the laboratory, it is necessary to evaluate the scale-up potential by using the unit equipment. In this study, bench-scale testing was performed to evaluate the scale-up properties of the thermomechanical and chemical treatment process, which consisted of three stages (1: Thermomechanical treatment, 2: Chemical treatment, 3: Wastewater treatment). In the first stage, lab, bench, and pilot scale thermomechanical tests were performed to evaluate the treated coarse aggregate and fines. In the second stage, the fine particles generated by the thermomechanical treatment process, were chemically treated using dissolution equipment, after then the removal efficiency and residual of cement in the small aggregate was compared with laboratory results. The final stage, the secondary wastewater containing contaminant nuclides was treated, and the contaminant nuclides could be removed by chemical precipitation method in the scale-up reactors. Furthermore, an additional study was required on the solid-liquid separation, which connected each part of the equipment. It was conducted to optimize the separation method for the characteristics of the particles to be separated and the purpose of separation. Therefore, it is expected that the basic engineering data for commercialization was collected by this study.
        2.
        2020.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Thermal decomposition of the uranyl phosphate mineral phase meta-ankoleite (KUO2PO4·3H2O) has been considered in relation to high temperature thermal sintering for the immobilisation of a uranyl phosphate containing waste. Meta-ankoleite thermal decomposition was studied across the temperature range 25 – 1200℃ under an inert N2 atmosphere at 1 atm. It is shown that the meta-ankoleite mineral phase undergoes a double de-hydration event at 56.90 and 125.85℃. Subsequently, synthetically produced pure meta-ankoleite remains stable until at least 1150℃ exhibiting no apparent phase changes. In contrast, when present in a mixed waste the meta-ankoleite phase is not identifiable after thermal treatment indicating incorporation within the bulk waste either as an amorphous phase and/or as uranium oxide. Visual inspection of the waste post thermal treatment showed evidence of self-sintering owing to the presence of glass former materials, namely, silica (SiO2) and antimony(V) oxide (Sb2O5). Therefore, incorporation of the uranium phase into the waste as part of waste sentencing and immobilisation via high temperature sintering for the purpose of long-term disposal is deemed feasible.
        4,000원
        3.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to investigate the influence of a two-week English-language orientation program at a Korean university on first-year students’ perceptions of English. This quantitative study contributes to the local literature by documenting the changes on a preand post-course survey that measured participants’ willingness to communicate, foreign language anxiety, attitudes towards English, and perceptions of English as a global language. Key results of independent-samples t-tests indicated that student perceptions showed statistically significant changes on five of the six scales, and that the biggest influences of the program were on willingness to communicate and lessening student anxiety. The study also investigated the link between program satisfaction and experience of studying English abroad, finding that there was no relation between them. However, a one-way ANOVA and correlation analysis indicated that there was a relationship between program satisfaction and students’ self-rated proficiency, finding that the lower-proficiency students were slightly less satisfied than those rating themselves as “average” or “good” English speakers. The study concludes with recommendations for future studies and for planning English-language orientation programs in Korean universities.
        5,500원
        4.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 동백나무의 간재적 추정식을 개발하고자 하였다. 제주지역에 자생하고 있는 동백나무 200본을 표준목으로 선정하여 분석 자료로 사용하였다. 재적모델 개발을 위해 80% 자료와 모델 타당성 검정(Validation)을 위해 20% 자료를 무작위로(Randomly) 구분하여 분석하였고, 본 연구에서 제시된 최종모형의 추정된 계수는 100% 자료를 이용하였다. 동백나무에 대한 재적 모델의 적합성 검정은 결정계수(R2), 추정치의 오차(RMSE), 평균편의(MD), 절대평균편의(AMD)와 직경급별 평균편의(MD), 변동계수(CV%)를 비교 분석하였다. 본 연구 결과, 결정계수는 0.7571에서 0.9381로 나타났으며, V=aDbHc에서 결정계수가 가장 높은 것으로 나타났다. 추정치의 오차는 0.0326으로 V=aD2H에서 가장 높았으며, 반면에 0.0258로 V=aDbHc에서 가장 낮았다. 평균편의는 V=a+bD2H에서 0에 값으로 나타났으며, V=aDbHc에서 0.0012로 나타났다. 절대평균편의는 V=D2/(a+b/H)에서 0.0186으로 가장 낮았고, 0.0223으로 V=aD2H에서 가장 높게 나타났다. 변동계수는 V=aDbHc에서 30.4348로 가장 적합한 계수로 나타났다. 5개의 모델식 중 최적의 식은 V=aDbHc에서 나타났으며 V=aD2H에서 적합성이 가장 낮은 것으로 나타났다.
        4,000원
        6.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 국가산림자원조사 자료를 이용하여 충남지역에 분포하는 사유림에 대한 포괄적인 개념의 산림경영율을 지역별, 임상별, 영급별, 경급별, 주요 수종별로 구분하여 분석하고자 하였다. 충청남도 사유림에서 조사된 제 5차 국가산림자원조사 자료 고정표본점은 총 971개소이며, 사유림 내에서 포괄적인 산림시업이 이루어진 고정표본점은 총 752개소로 나타났다. 본 연구 결과에 의하면, 충청남도 전체 사유림에 대한 포괄적인 산림경영율은 약 86.37%로 나타났다. 지역별 사유림에 대한 매년 연도별 산림 경영율은 공주시에서 14.07%로 가장 높은 경영율을 보였고 반면에 홍성군이 1.14%로 가장 낮은 경영율을 보였다. 임상별 산림경영율은 활엽수림에서 33.25%로 가장 높게 나타났으며, 반면에 혼효림에서 22.87%로 가장 낮게 나타났다. 영급은 3영급(33.77%)과 4영급(37.64%)에서 가장 높은 산림경영율로 나타났으며, 경급은 소경목(43.27%), 중경목(35.18%), 대경목(1.41%)으로 갈수록 산림경영율이 감소하는 경향을 보였다. 본 연구 결과는 충남지역에 분포하는 사유림의 포괄적인 사유림경영율에 대한 기초적인 정보를 제공할 수 있을 것으로 사료된다.
        4,000원
        9.
        2014.07 서비스 종료(열람 제한)
        New QTLs were identified for high grain yield with long panicle in rice. A total of 137 F15 recombinant inbred lines (RILs) derived from a cross between Dasanbyeo (Tongil) and TR22183 (japonica), together with the parents were evaluated for 16 agronomic traits at IRRI in dry and wet seasons under different phosphorus (P) and irrigation conditions. A linkage map was constructed using 236 polymorphic markers in 384-plex Bead Xpress indica-japonica single nucleotide polymorphism (SNP) platform. P and water effects were significant in both wet and dry seasons. Both parents and RILs showed varying degree of sensitivities to scarcities in water and phosphorus in terms of panicle length. Collocating with 20 yield-related QTLs, the panicle QTLs on chromosomes 1 (pl01) ,2 (pl02), 9 (pl09), and 11 (pl11) under low P and rainfed conditions were identified. RILs with TR22183 allele at pl11 showed longer panicle length under low P input rainfed condition in dry and wet seasons. The whole-genome sequences of the two varieties are being compared to design the molecular markers for fine-mapping and candidate gene identification. Based on Nipponbare MSU 7.0 annotation, a total of 1464 genes with predicted function were identified within the four QTL regions. Candidate genes identified in other studies for QTLs under low P and water conditions, such as calmodulin and dehydrin genes, were targeted for designing molecular markers for fine-mapping and expression analysis. Pyramiding the panicle length QTLs correlating with yield QTLs will provide an opportunity of improving yield traits.
        10.
        2013.07 서비스 종료(열람 제한)
        This study aims to identify major quantitative trait loci (QTL) for yield components under low-input systems in tropical regions in rice. A total of 156 highly advanced recombinant inbred lines (RILs) have been developed from a cross between two temperate rice varieties, Dasanbyeo (Tongil-type indica) and TR22183 (japonica). Both parental lines and RILs were tested under two different regimes of irrigation and phosphorus (P) application levels. During the wet season of 2012, under mild drought conditions, TR22183 showed more vigorous root growth at 15 days after sowing than Dasanbyeo. The early root establishment of TR22183 may have contributed to the enhanced P uptake from the top soil in the early growth stage. The linkage map for DT-RILs was constructed with 312 single nucleotide polymorphism markers aided by 384-plex platform of BeadXpress high-throughput genotyping system. For the vegetative growth, major QTLs on chromsome 6 for plant height and tiller numbers were identified. For the grain yield related traits, major QTLs on chromsome 2 were closely linked to each other. On the other hand, panicle length QTLs were identified on chromsomes 2 and 9. We are currently analyzing phenotypic data and the experiment is being repeated in dry season and temperate region.