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        검색결과 22

        2.
        2023.05 구독 인증기관·개인회원 무료
        A variety of microorganisms are contained in the groundwater and surrounding environment at the depth of a deep geological repository, and could adversely affect the integrity and/or safety of the facility under certain thermal, hydraulic and chemical conditions. In particular, microbial activity (in the buffer and backfill) around the canister can cause corrosion of the canister through sulfide production by sulfate-reducing bacteria (SRB), and subsequently promote radionuclide release through the corroded part. Namely, this phenomenon is important in a perspective of performance assessment since it will have an impact on the post-closure exposure dose in the biosphere by accelerating radionuclide leakage into the near-field due to deterioration of the canister integrity In Finland, the performance assessment on microbial activity in buffer, backfill, and plug was performed for the licensing. However, in Korea, researches relevant to microbial activity are only in the early stage as of now. Accordingly, in this study, we draw initial considerations for the performance assessment on the phenomenon in the domestic facility based on review results for the methodology carried out as part of operating license application (i.e. SC-OLA). Studies on the performance assessment of microbial activity in Finland were mainly performed: (a) to investigate complex interactions among microorganisms in the repository by analyzing both indigenous and exogenous microorganisms through drilling, geological and geochemical analysis, (b) to identify microbial interactions at the buffer, backfill, and host rock interface for specific microorganisms that may affect activity of other microorganisms and integrity of the repository, (c) to analyze canister corrosion caused by microbial activity, particularly sulfide production by SRB, and (d) to characterize microbial illitization of montmorillonite that could affect permeability, hydraulic conductivity, and structural integrity of the repository. From reviewing studies above, it is judged that studies labelled as (b) through (d) are applicable to the performance assessment of microbial activity for the domestic facility regardless of specific conditions in Korea. However, for study labelled as (a), the following data on reflecting domestic conditions should be additionally obtained: (1) radionuclide inventory and temperature in spent nuclear fuel, (2) swelling pressure and organic carbon content of bentonite, and (3) size, shape, and gas composition of pores in bentonite. Results of this study could be directly applied to the design and performance assessment for buffer and backfill components, provided that input data specific to the domestic disposal facility is prepared for the assessment required.
        3.
        2023.05 구독 인증기관·개인회원 무료
        In the engineered barrier system of deep geological disposal repository, complex physicochemical phenomena occur throughout the entire disposal time, consequently impacting the safety function. The bentonite buffer, a significant component of the engineered barrier system, can be geochemically altered due to the changes in host rock groundwater, temperature, and redox condition. Such changes may have direct or indirect effects on radionuclide migration in case of canister failure. Therefore, a modeling tool that accounts for coupled thermal-hydraulic-mechanical-chemical (THMC) processes is necessary for the safety assessment. To this end, the Korea Atomic Energy Research Institute (KAERI) has developed the APro, a modeling interface for conducting safety assessment of deep geological disposal repository. The APro considers coupled THMC processes that influence radionuclide migration. Here, the solute transport considering thermal and hydraulic processes are calculated using the COMSOL multi-physics, while geochemical reactions are carried out in PHREEQC. The two software are coupled using a sequential non-iterative operator splitting approach, and transport of non-water H, non-water O, and charge were additionally considered to enhance the coupling model stability. Finally, the applicability of APro to simulate long-term geochemical evolution of bentonite was demonstrated through benchmark studies to evaluate the effects of mineral precipitation/dissolution, temperature, redox, and seawater intrusion.
        6.
        2019.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        국내 고준위 방사성폐기물 심층처분시스템에 대한 프로세스 기반의 종합성능평가체계(APro) 개발을 위하여 사용자 편의성이 향상된 모델링 인터페이스를 구축하였다. APro의 모델링 인터페이스는 프로그래밍 언어인 MATLAB을 이용하여 구축되었고, 다중물리현상 모사가 가능한 COMSOL과 지화학반응 계산이 가능한 PHREEQC를 계산 엔진으로 활용하여 연산 자분리 방식을 적용하였다. APro는 모델링 영역을 기존의 정형화된 처분시스템으로 제한함으로써 모델의 자유도는 낮지만, 사용자 편의성을 향상시켰다. 처분시스템에서 고려되는 주요 현상들을 모듈화하였고, 이를“Default process”와 다수의“Alternative process”로 구분하여 사용자가 선택할 수 있도록 함으로써 모델의 유연성을 높였다. APro는 크게 입력자료 부분과 계산실행 부분으로 구성된다. 기본 입력자료는 하나의 EXCEL 파일에 일정한 포맷으로 정리되고, 계산실행 부분은 MATLAB을 이용하여 코딩되었다. 최종적인 전체 계산 결과는 독립적인 COMSOL 파일 형태로 생성되도록 하여 COMSOL을 이용한 계산 결과의 후처리가 가능하도록 하였다.
        4,000원
        7.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Le but de cette étude est de suggérer un échantillon d’ensembles d’outils de test pour évaluer l’évaluation basée sur les performances des tâches dans l’enseignement intégratif de la langue et de la culture françaises. À cette fin, cette étude a analysé les caractéristiques de l’évaluation basée sur la performance des tâches, la compétence communicative de Hymes, Canale, Swain et, Bachman et la compétence culturelle. En outre, cette étude a examiné les compétences de l’apprenant/utilisateur fournies par le Cadre européen commun de référence. Les résultats montrent: 1) les critères d’évaluation: compétence linguistique(connaissance du système linguistique, compétence du discours, compétence sociolinguistique), compétence culturelle(connaissance culturelle, attitude, compétence), compétence d’exécution de la tâche(connaissance procédurale, compétence d’exécution, compétence stratégique), 2) sous-catégorie et construction, et 3) auto-évaluation et évaluation par les pairs.
        5,200원
        10.
        2018.07 구독 인증기관·개인회원 무료
        Export diversification – the extent to which the firm seizes export sales opportunities across different nations and/or geographic regions – is a critical element of export marketing strategy. Yet, knowledge of the export performance consequences of export diversification is lacking. Underpinned by contingency and resource dependence theories, we examine the export diversification-export performance relationship as well as critical contingencies of this link. Based on a sample of UK exporters we find that firms gain the highest export performance benefits when they simultaneously increase national and regional export diversification. Our results also show that the export diversification-export performance link is weaker when firms operate in markets that are very in dynamism. Additionally, the relationship between export diversification and performance is stronger when both resource sharing and interfunctional coordination are high. Such contextual factors provide a better understanding of the diversification-performance relationship.
        12.
        2018.04 구독 인증기관·개인회원 무료
        A parametric study was carried out to gain an insight about structural performances considering abnormal behavior effects in high strength steel pipe strut system. Six load cases were considered as undesirable deflections of strut structures, which are basic load combination, excessive excavation situations, impact loading effects, additional overburden loads, load combinations, and 50% reduction of strut length. Subsequent simulation results present various influences of parameters on structural performances of the strut system. Based on the results, we propose methods to prevent unusual behaviors of pipe-type strut structures made of high strength steels.
        13.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The current practice in car headlight visibility performance evaluation is based on the luminous intensity and illuminance of headlight. Such practice can be inappropriate from a visibility point of view where visibility indicates abilities to perceive an object ahead on the road. This study aimed at evaluating the appropriateness of current headlight evaluation methodMETHODS: This study measured the luminance of object and road surface at unlit roadways. The variables were measured by vehicle type and by headlight lamp type. Based on the measurements, the distance where drivers can perceive an object ahead was calculated and then compared against such distance obtained by conventional visibility performance evaluation.RESULTS: The evaluation method based on illuminance of headlight is not appropriate when viewed from the visibility concept that is based on object-perceivable distance. Further, the results indicated a shorter object-perceiving distance even when road surface luminance is higher, thereby suggesting that illuminance of headlight and luminance of road surface are not the representative indices of nighttime visibility.CONCLUSIONS : Considering that this study utilized limited vehicle types and that road surface (background) luminance can vary depending on the characteristics of the given road surface, it would likely go too far to argue that this study’s visibility performance evaluation results can get generalized to other conditions. Regardless, there is little doubt that the current performance evaluation criterion which is based on illuminance, is unreasonable. There should be future endeavors on the current subject which will need to explore study conditions further, under which more experiments should be conducted and effective methodologies developed for evaluating automotive headlight visibility performance. Needs are recognized particularly in the development of headlight visibility performance evaluation methodology which will take into account road surface (background) luminance and luminance contrast from various perspectives as the former indicates the driver’s perception of the front road alignment and the latter being indicative of object perception performance.
        4,000원
        16.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구는 제7차 교육과정의 취지에 맞는 수준별 수업을 내실 있게 운영하기 위해서 시작하였다. 사교 육의 팽창으로 많은 학생들이 단순 문제 풀이식이나 반복 학습의 영향으로 이론에만 익숙할 뿐, 각 단원 의 학습 목표나 본질을 이해하지 못하는 경우가 적지 않다. 문학 작품마저도 스스로 찾아 읽고, 말이나 글로 즐거움을 공유하고 쌓아나가는 경험을 하지 못하는 실정이다. 수준별 수업의 효과를 높이기 위해서는 수업 방법은 물론, 새로운 평가 방법 마련이 절실하다. 수준별 수업을 실시하더라도, 그것을 일률적인 잣대로 평가하는 것은 무의미하다고 할 수 있다. 이에 연구자는 문학 단원을 중심으로 단원의 특성과 학습자의 수준에 적합한 수행평가 프로그램을 구안하고, 각 장르별 활동을 ‘따라하기’, ‘변화주기’, ‘확장하기’의 3단계로 구분하여 학습자가 자신의 흥미나 능력에 맞는 프로그램을 선택하여 활동하도록 하였다. 문학 장르와 활동 내용에 따라 수시로 수준을 이동· 선택할 수 있도록 함으로써 활동에 대한 흥미를 고조시켰다. 또한 학습 목표에 적합한 수준별 수행평가 기준안을 마련하고, 다양한 수준별 수행평가 자료를 구안·적용함으로써 학생들의 문학 작품 감상 능력 신장 방안을 모색하게 되었다.
        4,900원
        17.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 차량 이동하중을 받는 손상된 콘크리트 슬래브교량의 강성저하를 규명하고, 복합신소재를 사용하여 보강 후 성능평가를 수행한다. 특히 마이크로 유전알고리즘에 의한 역해석에 기반하여 보강 전·후 각 요소에서의 강성변 화를 수정된 2차변수 Gaussian 분포함수를 사용하여 정식화하였다. 본 연구에서 제안한 방법은 기존의 요소기반 접 근 방식에 비하여 수치해석적인 관점에서 효율성을 갖는다. 개발한 알고리즘은 3차원 솔리드 요소를 사용하여 모델 링한 교량의 동적 거동 시뮬레이션으로부터 계측한 데이터를 사전정보로 사용하여 검증하였다. 몇 가지 수치예제는 본 연구에서 개발한 방법이 실제교량과 수치모델간의 차이로 인한 오차 및 노이즈 등으로 인한 동적 계측치 오류 등이 고려되었음에도 강성분포 추정 및 성능 평가를 효율적으로 수행함을 보여준다.
        4,000원
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