• 한국수소및신에너지학회논문집
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• 제35권1호
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• pp.14-26
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• 2024

Global efforts continue with the goal of transition to a "carbon neutral (net zero)" society with zero carbon emissions by 2050. For this purpose, the technology of water electrolysis is being developed, which can store electricity generated from renewable energies in large quantities and over a long period of time as hydrogen. Recently, various research and large-scale projects on 'green hydrogen', which has no carbon emissions, are being conducted. In this paper, a comparison of water electrolysis technologies was carried out and, based on data provided by the International Energy Agency (IEA), large-scale water electrolysis demonstration projects were analyzed by classifying them by technology, power supply, country and end user. It is expected that through the analysis of large-scale water electrolysis demonstration projects, research directions and road maps can be provided for the development/implementation of commercial projects in the future.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1216-1225
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• 2014

Biofilm-related infections of Candida albicans are a frequent cause of morbidity and mortality in hospitalized patients, especially those with immunocompromised status. Options of the antifungal drugs available for successful treatment of drug-resistant biofilms are very few, and as such, new strategies need to be explored against them. The aim of this study was to evaluate the efficacy of phenylpropanoids of plant origin against planktonic cells, important virulence factors, and biofilm forms of C. albicans. Standard susceptibility testing protocol was used to evaluate the activities of 13 phenylpropanoids against planktonic growth. Their effects on adhesion and yeast-to-hyphae morphogenesis were studied in microplate-based methodologies. An in vitro biofilm model analyzed the phenylpropanoid-mediated prevention of biofilm development and mature biofilms using XTT-metabolic assay, crystal violet assay, and light microscopy. Six molecules exhibited fungistatic activity at ${\leq}0.5mg/ml$, of which four were fungicidal at low concentrations. Seven phenylpropanoids inhibited yeast-to-hyphae transition at low concentrations (0.031-0.5 mg/ml), whereas adhesion to the solid substrate was prevented in the range of 0.5-2 mg/ml. Treatment with ${\leq}0.5mg/ml$ concentrations of at least six small molecules resulted in significant (p < 0.05) inhibition of biofilm formation by C. albicans. Mature biofilms that are highly resistant to antifungal drugs were susceptible to low concentrations of 4 of the 13 molecules. This study revealed phenylpropanoids of plant origin as promising candidates to devise preventive strategies against drug-resistant biofilms of C. albicans.

• 통합자연과학논문집
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• 제4권2호
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• pp.113-120
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• 2011

Brassinosteroids (BRs) are plant steroid hormones that play essential roles in growth and development. Mutations in BR-signaling pathways cause defective in growth and development like dwarfism, male sterility, abnormal vascular development and photomorphogenesis. Transition from vegetative to reproductive growth is a critical phase change in the development of a flowering plant. In a screen of activation-tagged Arabidopsis, we identified a mutant named abz126 that displayed longer hypocotyls when grown in the dark on MS media containing brassinazole (Brz), an inhibitor of BRs biosynthesis. We have cloned the mutant locus using adapter ligation PCR walking and identified that a single T-DNA had been integrated into the ninth exon of the GIGANTEA (GI) gene, involved in controling flowering time. This insertion resulted in loss-of-function of the GI gene and caused the following phenotypes: long petioles, tall plant height, many rosette leaves and late flowering. RT-PCR assays on abz126 mutant showed that the T-DNA insertion in GIGANTEA led to the loss of mRNA expression of the GI gene. In the hormone dose response assay, abz126 mutant showed: 1) an insensitivity to paclobutrazole (PAC), 2) an altered response with 6-benzylaminopurine (BAP) and 3) insensitive to Brassinolide (BL). Based on these results, we propose that the late flowering and tall phenotypes displayed by the abz126 mutant are caused by a loss-of-function of the GI gene associated with brassinosteroid hormone signaling.

• 한국가스학회지
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• 제2권1호
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• pp.74-82
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• 1998

공정플랜트 설비 고온요소의 재질열화 정도를 평가하기 위해서 사용되는 방법 중 입계 부식법은 시험절차가 간단하고 실제 플랜트에서의 적용이 용이하여 안전 및 수명진단시에 많이 이용되어 왔다. 본 논문에서는 오랜 기간 고온에서 사용된 화학플랜트 및 정유플랜트의 실기 요소에 입계부식법을 적용하여 재질의 고온에서의 장시간 노출에 의한 인성열화도를 평가한 결과를 제시하였다. 실제 요소의 열화도 측정변수로서는 입계부식법으로 측정한 격자절단비 ($N_i/N_o$)를 사용했으며, 이로부터 인성열화도를 예측하였다. 인성열화도는 소형펀치 시험법으로 측정된 $({\Delta}DBTT)_{sp}$값으로 표현하였다. 격자절단비는 표면을 나이탈 부식했을 때의 격자수에 대한 피크린산으로 5분 부식했을 때의 격자수의 비율로 정의된다. 또한, 실험실에서 열처리된 시편으로부터 측정된 격자절단비와 Larson Miller Parameter와의 상관관계를 사용하여, 장시간 가동한 공정플랜트 요소에서 측정된 격자절단비로 잔여수명을 평가할 때의 고려사항에 대해 논의하였다.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1098-1108
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• 2019

Korea's first commercial nuclear power plant at Kori site was permanently shut down in 2017 and is currently in transition stage. Preparatory activities for decommissioning such as historical site assessment, characterization, and dismantling design are being actively carried out for successful D&D (Dismantling and Decontamination) at Kori site. The ultimate goal of decommissioning will be to ensure the safety of workers and residents that may arise during the decommissioning of nuclear facilities and, thereby finally returning the site to its original status in accordance with the release criteria. Upon completion of decommissioning, the resident's safety at a site released will be assessed from the evaluation of dose caused by radionuclides expected to be present or detected at the site. Although the U.S. commercial nuclear power plants with decommissioning experience use different site release criteria, most of them are 0.25 mSv/y. In Korea, both the unrestricted and restricted release criteria have been set to 0.1 mSv/y by the Nuclear Safety and Security Commission. However, since the dose is difficult to measure, measurable concentration guideline levels for residual radionuclides that result in dose equivalent to the site release criteria should be derived. For this derivation, site reuse scenario, selection of potential radionuclides, and systematic methodology should be developed in planning stage of Kori site decommissioning. In this paper, for calculation of a preliminary site-specific Derived Concentration Guideline Levels (DCGLs) for the Nuclear Power Plant site, a novel approach has been developed which can fully reflect practical reuse plans of the Kori site by taking into account multiple site reuse scenarios sequentially, thereby striking a remarkable distinction with conventional approaches which considers only a single site scenario.

• 대한토목학회논문집
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• 제42권6호
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• pp.775-786
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• 2022

원자력발전소 구조물을 포함하여 플랜트 구조물에서는 사용 중 설비보강을 위하여 벽체 및 슬래브에 관통부를 신설하는 경우가 빈번히 발생하고 있으며, 관통부 설치작업 중에 철근이 절단되는 사례가 일부 발생하고 있다. 이 관통부들은 설계 또는 건설 단계에서 고려된 것이 아니므로 설치 중 발생한 철근의 절단은 사실상 구조물의 손상이기 때문에, 관통부 주변 응력 전이범위 또는 유효폭을 고려한 구조물의 건전성 평가가 필요하다. 본 연구에서는 가동중인 원자력발전소 벽식 건물의 전단벽에 관통부를 신설할 경우에 발생하는 철근 절단의 영향을 평가하기 위하여 다양한 비선형 해석과 정적 가력 실험을 수행하였다. 그리고 관통부 신설과 철근의 절단으로 인한 벽체의 강성저하와 관통부 주변 철근의 응력 및 변형률 분포를 평가하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.210-215
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• 2001

The ferritic 2.25CrMo steel has been used for high temperature structure applications such as turbine rotors, boilers and pressure vessels in fossil plant and petroleum chemical facilities. However, this steel is known to result in aging degradation due to temper embrittlement, carbide induced brittleness and softening of matrix after long time exposure to high temperature. This research investigated the microstructural and mechanical changes after artificial degradation treatment and evaluated the degree of degradation by several nondestructive methods. The decrease of electrical resistivity and increase of magnetic Barkhausen noise(RMS voltage) with increasing aging time were observed. The change of electrical resistivity and Barkhausen noise showed a good correlation with the ductile-brittle transition temperature.

• 한국환경과학회지
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• 제12권1호
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• pp.15-22
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• 2003

Fifteen major naturally populated habitats around the Mt. Halla, Jeju province for wild Cornus kousa are mostly located on the southeast side of the mountains at 850-1,550m in altitude at sea level and are in half sunney areas. More than 40.0% of the naturally populated area of Cornus kousa are edge of forest areas and 53.3% populate on the steep slope of the mountain in 0-5℃. The direction of the slop for about 40.0% of total populated areas is southeast. In the naturally populated areas, total of 64 taxa dividing into 42 families, 59 genera 56 species and 8 varieties have been shown, mostly Hydrangea petiolaris, Rubus oldhamii, Ilex crenata, Sasa quelpaertensis, Ligustrum obtusifolium. It is suggested that these areas are secondary forest in a typical deciduous forest in Mt. Halla where the second transition had been progressed after forest damage or environmental stress. The index of species diversity of plant groups in these areas is 1.286-4.238 based on the Shannon-Wiener's method.

• 한국안전학회지
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• 제10권4호
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• pp.60-67
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• 1995

Ocassionally, many chemical plants experienced unexpected shutdown and suffered serious economic loss caused by boiler accidents due to mis-operations during the start-up or shutdown. A strategy to prevent such accidents is proposed here by using the form of frame for the recognition of all needed conditions, i.e., the states of the boiler, hazardous or dangerous conditions, each level conditions, transition network and heuristic knowledge of human operators. The expert system based on this strategy is considered to be an available method to predict all of the hazardous conditions in boiler plants.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.810-812
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• 1998

Analog I&C hardwares in most of nuclear power plants in operation are aging since they were installed 1950's or 1960's. Thus, the replacement of such systems with digital computer-based systems is currently a new trend in nuclear area. This paper will discuss such transition occurring in nuclear I&C area, Comparative study on the digital technique adopted in leading nuclear industries. Its advantage and performance evaluation will be illustrated as well.