• International Journal of Concrete Structures and Materials
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• 제7권3호
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• pp.225-238
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• 2013

In this study, a two-layer feed-forward neural network was constructed and applied to determine a mapping associating mix design and testing factors of cement-nano silica (NS)-rice husk ash ternary blended concrete samples with their performance in conductance to the water absorption properties. To generate data for the neural network model (NNM), a total of 174 field cores from 58 different mixes at three ages were tested in the laboratory for each of percentage, velocity and coefficient of water absorption and mix volumetric properties. The significant factors (six items) that affect the permeability properties of ternary blended concrete were identified by experimental studies which were: (1) percentage of cement; (2) content of rice husk ash; (3) percentage of 15 nm of $SiO_2$ particles; (4) content of NS particles with average size of 80 nm; (5) effect of curing medium and (6) curing time. The mentioned significant factors were then used to define the domain of a neural network which was trained based on the Levenberg-Marquardt back propagation algorithm using Matlab software. Excellent agreement was observed between simulation and laboratory data. It is believed that the novel developed NNM with three outputs will be a useful tool in the study of the permeability properties of ternary blended concrete and its maintenance.

• 예술인문사회 융합 멀티미디어 논문지
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• 제6권5호
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• pp.173-185
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• 2016

복수학위/교환학생 프로그램의 활성화로 강좌의 교수진과 학생들이 글로벌화되고 있다. 그동안 기존의 오프라인 위주의 강좌에서 벗어나 온라인 강좌나 블렌디드 학습 기반 강좌가 연구개발 되어 왔다. 하지만 기존의 연구는 대학 내에 국한되어 있어 복수학위나 교환학생 프로그램에 대한 고려는 이루어지지 않고 있다. 글로벌 강좌를 개발하고 운영하기 위해서는 비용이나 효율성 측면에서 여러 가지 어려움이 수반된다. 이를 효과적으로 해결하기 위한 방안으로 온/오프라인을 융합한 블렌디드 글로벌 강좌의 운영이 필요하며 이에 대한 연구가 시급하다. 이를 위해 본 연구에서는 블렌디드 글로벌 강좌 모형을 제시 개발하였다. 해외 석학 중심의 글로벌 강좌 개설 및 운영을 위해 블렌디드 러닝 방법을 반영하여 개설 시기와 온/오프라인 상호 유기적 관계에 따라 크게 8가지로 유형을 고안하고 이들 유형 간의 상호 비교 분석을 하였다. 본 연구에서 제안하는 블렌디드 글로벌 강좌는 글로벌시대에 적합한 인재를 대학에서 양성하는 데 적용할 수 있을 것이다.

• 한국IT서비스학회지
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• 제10권3호
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• pp.61-76
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• 2011

The purpose of this paper was to design and implement effective learning model for internet ethics education, following the learning principle and procedure of PBL(Problem-Based Learning) which is one of the constructivism teaching-learning theories(, and to apply it). In this learning model, online learning and face-to-face classes were systematically combined for achieving the teaching-learning goals and the main module for online learning run on Moodle, an open source LMS(Learning Management System). It is possible for learner to participate actively in creation of micro-contents and reorganize contents using various SNS(Social Network Service). The learner can achieve the learner-oriented learning and select micro-contents in order to reorganize the personalized learning contents to take advantage of SNS among learners. To examine educational effectiveness of the proposed learning model, an experimental study was conducted through the education content and method to the subjects of two classes in the second-grade of university located in OO city. 60 students(treatment group=30, control group=30) participated in the experiment. The result statistically verified that the proposed learning method is more effective in cultivating consciousness of internet ethics than the face-to-face PBL learning method. The results of this paper also showed that a lecture using blended learning is efficient in achieving learning performance and that learners responded positively(, which are indicating that the higher effectiveness of learning would be expected) by forming connectedness among learners using SNS. The results of this paper showed that a lecture using blended learning is effectiveness in achieving learning performance and that learners responded positively, which are indicating that the higher effectiveness of learning would be expected by forming connectedness among learners using SNS.

• 한국문헌정보학회지
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• 제55권2호
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• pp.179-200
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• 2021

본 연구는 학교도서관의 블렌디드 러닝을 활용한 자유학기제 독서동아리와 연계 프로그램을 중심으로 운영에 관한 사례를 분석하는 데 있다. 이에 본 연구에서는 블렌디드 기반의 학교도서관 운영에 대한 연구모형을 설계하였으며, 자유학기제 연계 프로그램의 참여자를 대상으로 학교도서관 독서동아리 활동에 대해 사례를 분석하였다. 분석 결과, 첫째, 연구모형의 관련변인에 대한 안정성, 일관성 및 예측가능성 신뢰도 검증의 모든 영역에서 신뢰수준을 만족하였다. 둘째, 블렌디드 활동과 진로탐색 및 진로설계 활동의 상관관계분석에서 유의한 관계가 검증되었다. 셋째, 블렌디드 러닝의 활동과 진로탐색 및 진로설계 활동 영역에서 비대면 활동에 유의한 정적인 영향이 나타나, 자유학기제 독서동아리 연계 프로그램은 비대면 활동에서 긍정적인 효과가 높은 것으로 검증되었다. 마지막으로 학교도서관 독서동아리 지원의 지자체 연계 프로그램을 제시하고, 학교도서관의 블렌디드 러닝에 관한 운영을 제안하였다.

• 컴퓨터교육학회논문지
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• 제11권6호
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• pp.11-27
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• 2008

컴퓨터 실습수업에서 웹기반 학습을 도입하여 효과적이라는 연구결과가 많이 있지만 웹기반 학습은 교수자와의 정의적 교류를 통한 인간적 피드백의 부족과 웹기반 학습에 적응하지 못하는 학습자가 발생할 수 있다는 문제점들이 있다. 본 논문에서는 수준별 학습을 위해 웹기반 학습을 도입하고, 웹기반 학습의 문제점 보완과 학자자간 학업성취도 격차를 좁히기 위해 동료교수법을 결합한 혼합학습의 효과를 밝혔다. 실험적인 목적을 위해 고등학교 학습자를 두 그룹으로 나누고, 엑셀 교수-학습 시스템을 개발하여 이를 두 그룹 모두에 적용해 웹기반 수준별 기본학습을 선행하도록 하였다. 선행학습 후 실습문제 해결을 위해 웹기반 학습과 동료교수법을 비교집단과 실험집단에 각각 적용하였다. SPSS에 의해 분석된 학업성취도 평가 결과는 웹기반 선행학습과 동료교수법을 결합한 혼합학습이 하업성취도 향상에 긍정적인 효과가 있었다는 것을 보여주었다. 특히 혼합학습을 적용한 실험집단의 중 하위권 학습자들이 학업성취도에 있어 많은 향상을 보이며 상위권 학습자들과 격차를 좁힌 것이 실험집단의 전체 학업성취도 향상에 주요원인으로 분석되었다.

• Journal of the Korean Statistical Society
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• 제24권2호
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• pp.349-360
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• 1995

This paper deals with the robustness properties of the minimum disparity estimation in linear regression models. The estimators defined as statistical quantities whcih minimize the blended weight Hellinger distance between a weighted kernel density estimator of the residuals and a smoothed model density of the residuals. It is shown that if the weights of the density estimator are appropriately chosen, the estimates of the regression parameters are robust.

• Computers and Concrete
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• 제13권1호
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• pp.97-115
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• 2014

Silica fume is a by-product of induction arc furnaces and has long been used as a mineral admixture to produce high-strength, high-performance concrete. Due to the pozzolanic reaction between calcium hydroxide and silica fume, compared with that of Portland cement, the hydration of concrete containing silica fume is much more complex. In this paper, by considering the production of calcium hydroxide in cement hydration and its consumption in the pozzolanic reaction, a numerical model is proposed to simulate the hydration of concrete containing silica fume. The heat evolution rate of silica fume concrete is determined from the contribution of cement hydration and the pozzolanic reaction. Furthermore, the temperature distribution and temperature history in hardening blended concrete are evaluated based on the degree of hydration of the cement and the mineral admixtures. The proposed model is verified through experimental data on concrete with different water-to-cement ratios and mineral admixture substitution ratios.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2014년도 춘계 종합학술대회 논문집
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• pp.399-400
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• 2014

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권6호
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• pp.693-704
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• 2017

Blended-Wing-Body Underwater Glider (BWBUG), which has excellent hydrodynamic performance, is a new kind of underwater glider in recent years. In the shape optimization of BWBUG, the lift to drag ratio is often used as the optimization target. However this results in lose of internal space. In this paper, the energy reserve is defined as the direct proportional function of the internal space of BWBUG. A motion model, which relates gliding range to steady gliding motion parameters as well as energy consumption, is established by analyzing the steady-state gliding motion. The maximum gliding range is used as the optimization target instead of the lift to drag ratio to optimizing the shape of BWBUG. The result of optimization shows that the maximum gliding range of initial design is increased by 32.1% though an Efficient Global Optimization (EGO) process.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권6호
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• pp.995-1006
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• 2015

Underwater glider, as a new kind of autonomous underwater vehicles, has many merits such as long-range, extended-duration and low costs. The shape of underwater glider is an important factor in determining the hydrodynamic efficiency. In this paper, a high lift to drag ratio configuration, the Blended-Wing-Body (BWB), is used to design a small civilian under water glider. In the parametric geometric model of the BWB underwater glider, the planform is defined with Bezier curve and linear line, and the section is defined with symmetrical airfoil NACA 0012. Computational investigations are carried out to study the hydrodynamic performance of the glider using the commercial Computational Fluid Dynamics (CFD) code Fluent. The Kriging-based genetic algorithm, called Efficient Global Optimization (EGO), is applied to hydrodynamic design optimization. The result demonstrates that the BWB underwater glider has excellent hydrodynamic performance, and the lift to drag ratio of initial design is increased by 7% in the EGO process.