• 디지털융복합연구
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• 제14권4호
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• pp.387-396
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• 2016

본 논문에서는 기존 연구논문과 달리 성별의 차이, 계열별 학문특성의 차이, 전형유형별 차이 등이 학업성취도에 미치는 영향을 분석하였다. 남자는 인문사회계열에서 학생부위주전형이 우수하고, 자연계열에서는 수능위주전형이 우수했다. 여자는 인문사회계는 수능과 학생부를 모두 사용하는 전형이 우수하지만 큰 차이는 없었다. 그러나, 자연계열은 수능위주전형이 우수한 것으로 나타났다. 예체능계는 뚜렷한 특징을 보이고 있지 않지만, 수능위주전형이 우수한 것으로 나타났다. 인문사회계는 남자와 여자 모두 학업성취도에서 큰 차이를 보이고 있지 않으므로 입학사정관제가 정착되고 성과를 내고 있는 것으로 나타났다. 하지만 자연계는 남자와 여자 모두 학업성취도가 수능위주전형보다 낮게 나타나고 있다. 이는 자연계열에서 중요한 과목이 수학과 과학이므로 나타나는 현상이다. 이를 해결하기 위해서는 자연계열의 입학사정관제는 수학 및 과학의 기초학업능력을 반영하여 선발되어야 하고, 또한 입학 후 수학 및 과학의 기초학업능력을 향상시킬 수 있는 추수지도 방안이 반드시 필요한 것으로 보인다.

• 정보교육학회논문지
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• 제17권2호
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• pp.177-189
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• 2013

국제학업성취도 비교 연구에 따르면 우리나라 학생들은 과학 수학교과에서 높은 수준의 학업성취결과를 나타낸 반면 학습 동기는 상대적으로 낮게 나타났다. 이에 본 연구는 엔지니어링 수업 모델을 적용한 로봇활용 STEM 융합교육 프로그램을 개발하였다. 프로그램의 주제는 4학년 과학교육과정의 한 단원이면서 학생들에게 친숙하고 로봇의 활용이 효과적인 '동물'로 정하였다. 로봇활용 STEM 프로그램은 로봇소양교육, 주제관련 교과학습, 엔지니어링 교육활동의 세 영역으로 구성되었다. 개발된 STEM 프로그램은 현장교사 14명으로부터 검토를 받았으며 연구결과 로봇 소양 유무에 상관없이 대부분의 교사가 프로그램의 목표, 내용 구성, 로봇의 활용에 대해 긍정적 반응을 나타내었다.

• Advances in concrete construction
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• 제10권4호
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• pp.289-299
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• 2020

A reliability analysis of the axial compressive load bearing capacity of postfire reinforced concrete (RC) columns strengthened with carbon fiber reinforced polymer (CFRP) sheets was presented. A 3D finite element (FE) model was built for heat transfer analysis using software ABAQUS. Based on the temperature distribution obtained from the FE analysis, the residual axial compressive load bearing capacity of RC columns was worked out using the section method. Formulas for calculating the residual axial compressive load bearing capacity of the columns after fire exposure and the axial compressive load bearing capacity of postfire columns retrofitted with CFRP sheets were developed. Then the Monte Carlo method was used to analyze the reliability of the axial compressive load bearing capacity of the RC columns retrofitted with CFRP sheets using a code developed in MATLAB. The effects of fire exposure time, load ratio, number of CFRP layers, concrete cover thickness, and longitudinal reinforcement ratio on the reliability of the axial compressive load bearing capacity of the columns after fire were investigated. The results show that within 60 minutes of fire exposure time, the reliability index of the RC columns after retrofitting with two layers of CFRPs can meet the requirements of Chinese code GB 50068 (GB 2001) for safety level II. This method is effective and accurate for the reliability analysis of the axial load bearing capacity of postfire reinforced concrete columns retrofitted with CFRP.

• Steel and Composite Structures
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• 제23권1호
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• pp.115-130
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• 2017

A new type of moment-resisting bolted connection was developed for use in composite steel- concrete construction to connect composite open section steel beams to concrete filled steel square tubular columns. The connection was made possible using anchored blind bolts along with two through bolts. It was designed to act compositely with the in-situ reinforced concrete slab to achieve an enhanced stiffness and strength. The developed connection was incorporated in the design of a medium rise (five storey) commercial building which was located in low to medium seismicity regions. The lateral load resisting system for the design building consisted of moment resisting frames in two directions. A major full scale test on a sub-assembly of a perimeter moment-resisting frame of the model building was conducted to study the system behaviour incorporating the proposed connection. The behaviour of the proposed connection and its interaction with the floor slab under cyclic loading representing the earthquake events with return periods of 500 years and 2500 years was investigated. The proposed connection was categorized as semi rigid for unbraced frames based on the classification method presented in Eurocode 3. Furthermore, the proposed connection, composite with the floor slab, successfully provided adequate lateral load resistance for the model building.

• Wind and Structures
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• 제29권6호
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• pp.405-416
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• 2019

Aerodynamic characteristic of a small scale wind turbine under the influence of an incoming uniform wind field is studied using k-ω Shear Stress Transport turbulence model. Firstly, the lift and drag characteristics of the blade section consisting of S826 airfoil is studied using 2D simulations at a Reynolds number of 1×10⁵. After that, the full turbine including the rotational effects of the blade is simulated using Multiple Reference Frames (MRF) and Sliding Mesh Interface (SMI) numerical techniques. The differences between the two techniques are quantified. It is then followed by a detailed comparison of the turbine's power/thrust output and the associated wake development at three tip speeds ratios (λ = 3, 6, 10). The phenomenon of blockage effect and spatial features of the flow are explained and linked to the turbines power output. Validation of wake profiles patterns at multiple locations downstream is also performed at each λ. The present work aims to evaluate the potential of the numerical methods in reproducing wind tunnel experimental results such that the method can be applied to full-scale turbines operating under realistic conditions in which observation data is scarce or lacking.

• Steel and Composite Structures
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• 제36권5호
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• pp.587-602
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• 2020

In recent years, the composite columns have been widely used in the structures. These columns are mainly used to construct the structures with a large span and high floor height. Concrete filled tubes (CFTs) are a type of composite column, which are popular nowadays due to their numerous benefits. The purpose of this study is to investigate such frames at elevated temperatures. The method used in this research is based on section 2.2 of Eurocode 4. First, for the verification purpose, a comparison was made between the experimental results and the numerical model of the concrete filled tube. Then a composite frame was analyzed under fire temperature with different parameters. The results showed that the failure time decreased with increasing the friction of different models. Moreover, investigation of the concrete moisture content revealed that an increase in the concrete moisture content from 3% to 10% led to extended failure time for different models. For instance, in the second frame model, the failure time has increased up to 8%.

• 한국농공학회논문집
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• 제62권1호
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• pp.61-70
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• 2020

To estimate the ventilation volume of mechanically ventilated swine farms, various regression models were applied, and errors were compared to select the regression model that can best simulate actual data. Linear regression, linear spline, polynomial regression (degrees 2 and 3), logistic curve, generalized additive model (GAM), and gompertz curve were compared. Overfitting models were excluded even when the error rate was small. The evaluation criteria were root mean square error (RMSE) and mean absolute percentage error (MAPE). The evaluation results indicated that degree 3 exhibited the lowest error rate; however, an overestimation contradiction was observed in a certain section. The logistic curve was the most stable and superior to all the models. In the estimation of ventilation volume by all of the models, the estimated ventilation volume of the logistic curve was the smallest except for the model with a large error rate and the overestimated model.

• Journal of Information Technology Applications and Management
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• 제21권3호
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• pp.65-77
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• 2014

Ubiquitous learning has aroused great interest and is becoming a new way for foreign language education in today's society. However, how to increase the learners' initiative and their community cohesion is still an issue that deserves more profound research and studies. Emotional intelligence can help to detect the learner's emotional reactions online, and therefore stimulate his interest and the willingness to participate by adjusting teaching skills and creating fun experiences in learning. This is, actually the new concept of smart education. Based on the previous research, this paper concluded a neural mechanism model for analyzing the learners' emotional characteristics in ubiquitous environment, and discussed the intelligent monitoring and automatic recognition of emotions from the learners' speech signals as well as their behavior data by multi-agent system. Finally, a framework of emotional intelligence system was proposed concerning the smart foreign language education in ubiquitous learning.

• Current Optics and Photonics
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• 제1권5호
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• pp.468-473
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• 2017

We determined the feasibility of a fishing camera system using an optical fiber as the fishing line by testing a power-over-fiber (POF) module and multimode optical fiber. Operation of the remote camera module (RCM) without the battery was preferred because the removal of the charging or battery replacement section enabled a waterproof single-body type design. The average efficiency of the photovoltaic power converter (PPC) in the tested POF module was 32.6% at 820 nm, and thus, a high-power laser of at least 1.27 W was required for operating the developed RCM with an electrical dissipation of 413 mW. Because the optical fiber was wound on a fishing reel, composite loss composed of bending and tensile loss occurred. To mitigate the composite loss, we employed a simple holder that showed an improvement in the composite loss of 0.38 dB to 0.8 dB, which was considerably better than the losses without the holder.

• Structural Engineering and Mechanics
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• 제71권6호
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• pp.713-738
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• 2019

In the paper the dynamics of the oscillating moving load acting in the interior of the hollow cylinder surrounded with elastic medium is studied within the scope of the exact field equations of 3D elastodynamics. It is assumed that the oscillating load act on the certain arc of the internal circle of the cylinder's cross section and this load moves with constant velocity along the cylinder's axis. The corresponding 3D dynamic problem is solved by employing moving coordinate system, the exponential Fourier transform and the presentation these transforms with the Fourier series. The expressions of the transforms are determined analytically, however their originals are found numerically. Under the investigations carried out in the paper the main attention is focused on the so-called "gyroscopic effect", according to which, the influence of the vibration frequency on the values of the critical velocity and interface stresses are determined. Numerical results illustrated this effect are presented and discussed. In particular, it is established how the non-axisymmetricity of the problem acts on the influence of the load oscillation on its critical velocity and on the interface stresses.