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        검색결과 33

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Bellows expansion joints enhance the displacement performance of piping systems owing to their unique geometrical features. However, structural uncertainties such as wall thinning in convolutions, a byproduct of the manufacturing process, can impair their structural integrity. This study addresses such issues by conducting a global sensitivity analysis to assess the impact of these uncertainties on the performance of bellows expansion joints under monotonic loading. Global sensitivity analysis, which examines main and nth order interaction effects, is computationally expensive. To mitigate this, we employed a surrogate model-based approach using an artificial neural network. This model demonstrated robust prediction capabilities, as evidenced by metrics such as the coefficient of determination. The sensitivity indices of the main effect for the 2-ply and 3-ply bellows at the sixth convolution were 0.3340 and 0.3233, respectively. The sensitivity index of the sixth convolution was larger than that of other convolutions because the maximum deformation of the bellows expansion joint under monotonic bending load occurs around it. Interestingly, the sensitivity index for the interaction effect was negligible (0.01%) compared to the main effect, suggesting minimal activity between uncertainty factors across convolutions. Notably, bellows expansion joints under repetitive loading exhibit more complex behaviors, with the initial leakage typically occurring at the convolution. Therefore, future studies should focus on the structural uncertainties of bellows expansion joints under cyclic loading and employ a surrogate model for comprehensive global sensitivity analysis.
        4,000원
        2.
        2022.05 구독 인증기관·개인회원 무료
        To obtain confidence in the safety of disposal facilities for radioactive waste, it is essential to quantitatively evaluate the performance of the waste disposal facilities by using safety assessment models. Thus, safety assessment models require uncertainty management as a key part of the confidencebuilding process. In application to the numerical modelling, the global sensitivity analysis is widely employed for dealing with parametric and conceptual uncertainties. In particular, the parametric uncertainty can be effectively reduced by minimizing the uncertainty of critical parameters in the safety assessment model. In this paper, the numerical model of each step disposal facility (Silo, Near surface, and Trench type) at Wolsong Low and Immediate Level Waste (LILW) Disposal Center is designed by using a two-dimensional finite element code (COMSOL Multiphysics). In order to determine the critical parameters for non-adsorbed nuclides such as H-3, C-14, Tc-99, we introduced the variance-based sensitivity analysis methodology of the global sensitivity analysis. In the case of Silo type, the density of waste is highly sensitive to the total leakage quantity of all nuclides. Additionally, the initial nuclide concentration of H-3 was identified as another important parameter of H-3. On the other hands, the mass transport coefficient showed a high contribution in C-14 and Tc-99. In other types of disposal facilities, the leaking properties of H-3 are significantly affected by the amount of infiltration water. However, C-14 and Tc-99 were found to be more sensitive to the density of waste.
        3.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The multi-layered heat source model is a model that can cover most of existing studies and can be defined with a simple formula. Based on the methodology performed in previous studies, the welding heat source was found through experiments and FEM under the welding power conditions of three cases and the parameters of the welding heat source were analyzed according to the welding power. In this study, parameters of fiber laser welding heat source according to welding power were searched through optimization algorithm and finite element analysis, and the correlation was analyzed. It was confirmed that the concentration of the welding heat source in the 1st layer was high regardless of the welding power, and it was confirmed that the concentration of the welding heat source in the 5th layer (last layer) increased as the welding power increased. This reflects the shape of the weld bead that appears during actual fiber laser welding, and it was confirmed that this study represents the actual phenomenon.
        4,000원
        4.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a welding heat source model was presented and verified during fiber laser welding. The multi-layered heat source model is a model that can cover most of existing studies and can be defined with a simple formula. It consists of a total of 12 parameters, and an optimization algorithm was used to find them. As optimization algorithms, adaptive simulated annealing, multi island genetic algorithm, and Hooke-Jeeves technique were applied for comparative analysis. The parameters were found by comparing the temperature distribution when the STS304L was bead on plate welding and the temperature distribution derived through finite element analysis, and all three models were able to derive a model with similar trends. However, there was a deviation between parameters, which was attributed to the many variables. It is expected that a more clear welding heat source model can be derived in subsequent studies by giving a guide to the relational expression and range between variables and increasing the temperature measurement point, which is the target value.
        4,000원
        5.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Welding is the most widely used technology for manufacturing in the automobile, and shipbuilding industries. Fiber laser welding is rapidly introduced into the field to minimize welding distortion and fast welding speed. Although it is advantageous to use finite element analysis to predict welding distortion and find optimized welding conditions, there are various heat source model for fiber laser welding. In this study, a welding heat source was proposed using a multi-layered heat source model that encompasses most of the existing various welding heat source models: conical shape, curved model, exponential model, conical-cylindrical model, and conical-conical model. A case study was performed through finite element analysis using the radius of each layer and the ratio of heat energy of the layer as variables, and the variables were found by comparing them with the actual experimental results. For case study, by applying Adaptive simulated annealing, one of the global optimization algorithms, we were able to find the heat source model more efficiently.
        4,000원
        6.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        예비유아교사의 글로벌 마인드는 미래사회의 글로벌리더인 유아와 그 가족뿐 만 아니라 미래의 글로벌 시민교육의 측면에서 매우 중요하다. 본 연구는 포괄 적이고 광범위한 글로벌 마인드의 개념에 대한 교직인성관련 구성요인을 탐색 하고, 교직인성교육을 실행하였다. 예비유아교사의 글로벌 마인드 함양을 위해 J지역 예비유아교사 175명을 대상으로 6개요인 28문항을 구성하였다. 프로그램 실행 결과, 사전-사후 비교 및 학년별 비교에서 통계적으로 유의한 차이를 나타내었다(p< .05). 예비유아교사의 글로벌 마인드 함양과정은 미래에 사라질 직업이라는 불안감 과 두려움으로 나타났으나, 다름은 다양함으로, 두려움은 호기심으로, 회피적인 성향은 다가서려는 노력으로, 낯설음은 새로움으로 변화과정을 나타내었다. 교직인성과 관련해 포괄적인 개념을 모두 반영하지 못한 제한점이 있으나, 예비유아교사의 글로벌 마인드 함양을 위한 교육모형을 제시한 점에서 의의를 찾아볼 수 있다.
        6,700원
        7.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 교육부의 개정교육과정(2015)에서 제시한 교육목표인 창의융합형 인재와 제 4차 산업혁명에 따라 요구되는 글로벌 인재는 그 맥을 같이한다고 보고, 이러한 인재를 ‘글로벌 영리더’로 재개념화한 다음, 그 육성을 효과적으로 지 원하기 위한 모델-도구-프로그램을 개발·체계화하기 위해 3가지 연구문제를 설정하고 수행하였다. 첫째, 코칭접근을 통해 창의융합형 인재육성을 지원하는 마음의 길(MW : Mind Way) 코칭모델을 개발하는 것으로, 교육부에서 제시한 6가지 일반 역량을 재개념화하여 심성, 본성, 적성, 감수성, 창조성, 사회성의 6개 발달영역에서 통합적 탁월성(excellence)이 발휘될 수 있도록 통섭(consilience)적 접근을 통해 본 연구자에 의해 기 개발된 WISE 모델과 통합·개발하였다. 둘째, MW 코칭모델을 구성하는 요소 중 핵심요소에 해당하는 ‘심성’의 상태를 파악하기 위한 도구인 멋진 마음의 길(W-MW : Wonderful Mind Way)을 개발·타당화하는 것으로, ‘조하리의 창(Johari’s window)’을 원용하여 52가지 형용사로 구성된 도구를 개발하였다. 셋째, MW 코칭모델에 기반한 프로그램을 구성하는 것으로, 일반 아동‧청소 년을 위한 Grace & Force 프로그램과 크리스천 아동‧청소년을 위한 Grace & Force-CE 프로그램의 틀을 제시하였다. 본 연구의 결과를 바탕으로 하여 후속연구(2)에서는 Grace & Force 및 Grace & Force-CE 프로그램의 효과를 M-MW 도구를 사용하여 분석함으로써 MW 코칭모델의 이론적 타당성과 실천적 효과성을 확인할 수 있을 것이다.
        7,000원
        8.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The estimation of heat source model is very important for heat transfer analysis with finite element method. Part I of this study used adaptive simulated annealing which is one of the global optimization algorithm for anticipating the parameters of the Goldak model. Although the analysis with 3D model which depicted the real situation produced the correct answer, that took too much time with moving heat source model based on Fortran and Abaqus. This research suggests the procedure which can reduce time with maintaining quality of analysis. The lead time with 2D model is reduced by 90% comparing that of 3D model, the temperature distribution is similar to each other. That is based on the saturation of heat transfer among the direction of heat source movement. Adaptive simulated annealing with 2D model can be used to estimate more proper heat source model and which could enhance to reduce the resources and time for experiments.
        4,000원
        11.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Anticipation of welding deformation with finite element method is a very interested topic in the industries, adequate heat source model is essential for concluding reasonable results. This study is related to estimate the parameters of Goldak heat source model, and global optimization algorithm is applied to this research. The heat affected zone (HAZ) boundary line of bead on plate (BOP) welding is used as the target, parameters of heat sources are used as the variables. Adaptive simulated annealing is applied and the optimal result is obtained out of 1,000 candidates. The convergence of finite element method and the global optimization is meaningful for estimation of welding deformation, which could enhance to reduce the resources and time for experiments.
        4,000원
        12.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Biogeochemical processes play an important role in ocean environments and can affect the entire Earth’s climate system. Using an ocean-biogeochemistry model (NEMO-TOPAZ), we investigated the effects of changes in albedo and wind stress caused by phytoplankton in the equatorial Pacific. The simulated ocean temperature showed a slight decrease when the solar reflectance of the regions where phytoplankton were present increased. Phytoplankton also decreased the El Niño-Southern Oscillation (ENSO) amplitude by decreasing the influence of trade winds due to their biological enhancement of upper-ocean turbulent viscosity. Consequently, the cold sea surface temperature bias in the equatorial Pacific and overestimation of the ENSO amplitude were slightly reduced in our model simulations. Further sensitivity tests suggested the necessity of improving the phytoplankton-related equation and optimal coefficients. Our results highlight the effects of altered albedo and wind stress due to phytoplankton on the climate system.
        4,600원
        13.
        2017.06 구독 인증기관 무료, 개인회원 유료
        As the fourth industry revolution is starting, most of the fields including education are rapidly being changed. In parituclar, research on IT or SW fusion in each field is being performed. This paper discusses novel approaches to improve previous education services through IT fusion. First, I propose a way to converge IT into global education, which focuses on students of the college of education who are interested in becoming teachers. Due to internationalization demands in the field of education, the necessity of global education is increasing rapidly. However, a general consensus of the definition and model for global education is not clear yet and the actual performance falls short of our expectations owing to high cost, low effectiveness, and lack of persistence in the process of global education. To overcome the limits of global education and develop an efficient education system, this research suggests an IT-fusion-based education system for training global teachers. Second, it is difficult for an instructor to grasp instantly how much learners understand learning content in class in a typical education environment. In case of a class, which consists of possibly dozens of students at various levels ; trying to understand degree and learning achievement of the learners in a broad spectrum, depending on the learning contents. Therefore, it is almost impossible for an instructor to let all of the learners reach a specific learning objective. In this paper, I propose an approach that enables the arbitrary rate of learners, who reach a learning goal, to be set by an instructor. I describe an instruction support system combined with an instant response system, dynamic formative evaluation scheme, and confidence level. I expect that this approach can make an instructor set the ratio of learners, who reach the learning objective, as the instructor wants, and brings about effective instruction. Third, this study proposes a new learning model for improving problem solving and programming skills. To solve a real world problem using IT, problem solving and programming skills are important. In this study, I describe a learning model that can help to improve problem solving and programming skills, based on computational thinking. The feature of the learning model proposed is to offer learners challenges and spur interest by presenting the questions into learning games of an intercompetition type after developing the questions that improve problem solving and programming skills. Another feature is to present the questions about algorithms and programming in various forms and generate them dynamically. Especially, by providing an inter-competition game type, due to increase of competition between learners, learners will feel relatively less difficulty in problem solving and programming, and enable them to naturally improve problem solving abilities and programming skills through the competition.
        4,000원
        14.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구에서는 지표 관측 자료와 위성 자료 그리고 GWNU 단층 복사 모델을 이용하여 맑은 상태의 전천 일사 량을 계산하였으며, 전운량에 따라 관측 및 모델의 일사량 값을 비교 분석하였다. 연구 자료는 2012년 강릉원주대학교 복사 관측소의 전천 일사량, 기온, 기압, 습도, 에어로졸 등의 관측 자료와 OMI 센서의 오존전량 자료 그리고 구름의 유무 및 전운량을 판단하기 위하여 자동 전운량 장비인 Skyview 자료를 이용하였다. 전운량이 0 할인 맑은 날의 경우 관측 값과 모델 값이 0.98로 높은 상관계수를 나타내었으나 RMSE가 36.62Wm−2로 비교적 높게 나타났다. 이는 Skyview 장비가 얇은 구름이나 박무 및 연무 등의 기상상태를 판단하지 못하였기 때문이다. 흐린 날의 경우 구름의 영 향을 보정하기 위해 전운량과 두 값의 차에 대한 비율을 이용한 회귀식을 복사 모델에 적용하였으며, 장비의 오탐지를 제외한 경우 상관계수가 0.92로 높은 상관성을 보였으나 RMSE가 99.50 Wm−2으로 높은 값을 보였다. 더 정확한 분석 을 위해서는 직달 성분의 차폐 유무 및 구름 광학 두께를 포함한 다양한 구름 요소의 추가적인 분석이 요구된다. 이 연구결과는 분 또는 시간에 따른 일사량을 산출하여 일사량이 관측되지 않는 지역에서 유용하게 사용될 수 있다.
        4,300원
        15.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        기존 구조물의 모델 업데이팅 기법은 주로 진동 계측을 통해 얻은 전역적 구조 응답-모달 파라미터-를 이용한다. 모달 파라미터를 이용하여 업데이트된 모델은 전역적 구조 응답을 잘 추정할 수 있지만, 부재 레벨의 안전성 평가를 위한 국부적 응답 예측에는 어려움이 있다. 구조물 내 구조 부재들의 변형률 계측을 통해 응력을 추정하고, 안전성 평가가 이루어진다. 따라서, 본 연구는 모달 파라미터 이외에 로컬 구조 부재들에 가하는 해머 가력을 통해 계측한 변형률을 추가적으로 모델 업데이팅에 이용한다. 본 연구가 제안하는 모델 업데이팅에서 목적함수는 전역적/국부적 계측 응답과 모델의 응답간의 차로 설정되며 NSGA-II를 이용하여 이를 최소화된다. 업데이트 모델에서 예측하는 변형률 응답은 철골조의 안전성 평가에 활용된다. 제안한 기법은 철골 프레임에 대한 시뮬레이션과 해머 가력 실험을 통해 검증된다.
        4,000원
        17.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, due to the instability of the domestic market, global competition is intensifying in the current situation of global capacity building of SMEs for the purpose of developing a diagnostic indicator placed on the purpose. In this model, the results of applying several companies overall global innovation pilot enterprises and non-rated global innovative companies awarded significant difference between the score and the ability to believe the show. Non-global innovation companies, the relative firm size factor and R&D investment and patent number of factors are lacking appeared shone This is a common small business nature of the majority of companies small and R&D investment, the absolute amount is insufficient to reflect that, but the global innovator in the case of firm size and the relatively large amount of investment that never shows.
        4,000원
        18.
        2012.12 구독 인증기관 무료, 개인회원 유료
        During the past decades, the island city of Jeju, through considerable multi- sectoral efforts, has grown to be a shining example of an environmental hub model. The origin of Jeju’s growth as a global environmental hub can be traced primarily to two major characteristics: 1. The willingness of the people of Jeju to share their island’s vibrant cultural heritage and unique natural beauty with the rest of the world, and 2. The tireless endeavors of Jeju Special Self-GoverningProvince to manage Jeju’s environment, and share its environmental best practices to urban centers across the world. These endeavors are expressed as the principal of policy that conservation is prior to development. In order to achieve its goal of a World Environmental Hub status, Jeju Special Self- Governing Province is promoting 1) institutional strategies, 2) supplementation of its existing master plan, and 3) restructuration of existing social system. The first includes the promotion of this project on a joint base with IUCN and the Ministry of Environment of the Republic of Korea, establishment of head office of world environmental hub promotion in Jeju Governmental organization, and enactment of world environmental hub special law by the National Assembly of the Republic of Korea. The second is considering collaborations with the members of IUCN commissions, domestic experts, and consultants who will be recruited from overseas. The third is for improving the effectiveness and efficiency of the master plan through the restructuring of exiting socio-economic system to a new one focusing on maximizing the eco-efficiency and environ- mentally friendly behavior.
        4,200원
        19.
        2011.05 구독 인증기관·개인회원 무료
        Light brown apple moth, Epiphyas postvittana, is a significant horticultural pest native to Australia, and currently with a limited global distribution. However it can tolerate very heterogeneous climatic and vegetation conditions and has recently invaded California with considerable consequences for US international and domestic trade. By comparing the climatic conditions of its native (Australia) and long-established (New Zealand) ranges to the rest of the world using CLIMEX, it was suggested that E. postvittana has potential to establish mainly in countries in Central and South America, southern Africa, west Europe and South-east Asia. However, the predicted global distribution of E. postvittana using a new multiple-species-distribution model system suggested that there are additional climatically suitable areas around the world where this species could potentially survive and establish. Our study provides basic but important information for further assessment of the establishment capacity of this species in new habitats, wihch will provide the knowledge required to make science-based decisions in biosecurity.
        20.
        2008.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,600원
        1 2