• Educational Technology International
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• v.22 no.2
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• pp.255-283
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• 2021

In the early 2020, COVID-19 changed the traditional way of teaching and learning. This paper aimed to explore the impact of college students' perception of course quality on their online learning satisfaction. A total of 4,812 valid samples were extracted, and the difference analysis and hierarchical regression analysis were used to make an empirical analysis of college students' online learning satisfaction. The research results were as follows. Firstly, there was no difference in online learning satisfaction among students by gender and grade. Secondly, learning assessment, course materials, course activities and learner interaction, and course production had a significant positive impact on online learning satisfaction. Course overview and course objectives had an insignificant correlation with online learning satisfaction. Thirdly, the total effect of online learning satisfaction was as follows. Course production had the greatest effect, followed by course activities and student-student interactions, followed by course materials. It was the learning evaluation that showed the least effect. This study can provide empirical reference for college teachers on how to continuously improve online teaching and increase students' satisfaction with online learning.

• Journal of information and communication convergence engineering
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• v.21 no.2
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• pp.152-158
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• 2023

In recent years, as computer-generated imagery has been applied to more industries, realistic facial animation is one of the important research topics. The current solution for realistic facial animation is to create realistic rendered 3D characters, but the 3D characters created by traditional methods are always different from the actual characters and require high cost in terms of staff and time. Deepfake technology can achieve the effect of realistic faces and replicate facial animation. The facial details and animations are automatically done by the computer after the AI model is trained, and the AI model can be reused, thus reducing the human and time costs of realistic face animation. In addition, this study summarizes the way human face information is captured and proposes a new workflow for video to image conversion and demonstrates that the new work scheme can obtain higher quality images and exchange effects by evaluating the quality of No Reference Image Quality Assessment.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.343-344
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• 2021

최근 영상의 활용도의 증가에 따라, 비정형 영상 데이터에 대한 양이 기하급수적으로 증가하였다. 디지털 영상을 획득할 시에 처리/압축/저장/전송/재생산 등의 과정을 거치면서 왜곡을 수반하게 되며 영상의 품질을 저하시키는 요인이 된다. 영상의 품질은 활용 결과에도 큰 영향을 미치기 때문에 품질이 저하된 영상은 분류를 하는 것이 중요하다. 하지만 사람이 수신된 모든 영상에 대해서 직접 분류를 하는 것은 많은 시간과 비용이 소요된다는 문제점이 존재한다. 따라서 본 논문에서는 사람이 인지하는 주관적인 영상 품질 평가와 유사하게 품질에 대한 평가를 위한 왜곡영상의 특징정보를 검출 및 분석하는 방안에 대해서 제안한다. 본 방법은 사람이 영상을 인지할 때 가장 많이 사용되는 요소인 색상에 대한 선명도, 블러와 노이즈에 대한 특징정보를 이용한다. 검출된 특징정보를 공간 도메인으로 변환함으로써 왜곡 영상별 특성을 분석하였다. 실험을 위해서 IQA 데이터베이스인 LIVE를 이용하였으며, 원본영상 및 5가지 유형의 왜곡영상으로 구성되어 있다. 실험결과 품질이 좋은 영상과 왜곡영상에 대한 특성을 검출할 수 있었다.

• Iberoamérica
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• v.14 no.1
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• pp.57-80
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• 2012

This year(2012) marks the 30th anniversary of the Malvinas (Falkland) war. A series of talks between the British and Argentina took place over 30 years until 1982, but failed to reach a conclusion on sovereignty. Argentina claims that sovereignty of the islands was transferred to Argentina from Spain upon independence, a principle known as uti possidetis juris. But UK claims that the principle of uti possidetis juris is not accepted as a general principal of international law, and UN General Assembly resolutions calling for negotiations are flawed because they make no reference to the islanders' right to choose their own future. In this situation, a huge amount of petroleum and natural gas has discovered near the Malvinas islands. To explore such situation, this article looks into history and present condition on dispute of Malvinas sovereignty, and also analyses de-colonialism and resource nationalism related to dispute of Malvinas sovereignty.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3602-3607
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• 2024

The present work is devoted to implementation of the stilbene-based neutron spectrometer energy calibration method. The results of experiments with portable neutron generators and 238PuBe source and scattering materials with known cross sections are used for this method. It is shown that the submitted method makes it possible to carry out fast neutron spectrometry in the energy range from 1 to 15 MeV with the uncertainty of the unfolded neutron energy no more than 200 keV. Neutron spectra unfolding was carried out based on the measured spectra and a Geant4 simulated response matrix. Unfolded spectra were compared with the literature data and reference spectra.

• Journal of Environmental Health Sciences
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• v.45 no.2
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• pp.113-125
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• 2019

Objectives: Although the risk assessments for nitrogen dioxide ($NO_2$) and ozone ($O_3$) have been extensively studied, most of the existing risk assessments were limited mainly to indoor environments such as workplaces, schools, and multi-use facilities. Therefore, integrated risk assessment is needed to consider exposure in all microenvironments, including outdoors. The purpose of this study was to assess the differences in risk among sub-population groups according to time-activity patterns and reported concentrations, as well as the lifetime risk of Koreans. Methods: In this study, we estimated time-weighted average exposure concentrations of $NO_2$ and $O_3$ for preschool children, students, housewives, workers, and seniors using residential time and indoor concentrations (house, school or workplace, other), outdoors, and transport by meta-analysis method. The risk for $NO_2$ and $O_3$ were assessed by hazard quotient using reference concentrations 30 and 60 ppb, respectively. The risk assessments were conducted through 1,000,000 Monte-Carlo simulations for probabilistic analysis. Results: Preschool children, students, housewives, workers, and seniors spent 91.9, 86.0, 79.8, 82.2, and 77.3% of their day in a house, school, or workplace, respectively. The risk assessment for the lifetime of a housewife and a worker showed that 33.8 and 28.4% of hazard quotients of $NO_2$ exceed 1, respectively, and more than 99% of hazard quotient of $O_3$ were less than 1. Conclusions: The risk of $NO_2$ and $O_3$ by sub-population group and for the lifetime of housewives and workers were assessed. The risk for $NO_2$ was higher than for $O_3$ and showed a different risk by sub-population group. Both $NO_2$ and $O_3$ showed a higher risk for housewives than for workers. This study can be used as a basis for lifetime exposure and risk assessment for $NO_2$ and $O_3$.

• International Journal of Industrial Entomology and Biomaterials
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• v.3 no.1
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• pp.19-23
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• 2001

Two B. thuringiensis strains, which possess mosquitocidal activities, were isolated from Korean soil samples and named K-1205-1 and K-1381-1. Serological studies indicated that K-1205-1 and K-1381-1 belonged to B. thuringiensis subsp. kurstaki (H3a3b3c) and subsp. aizawai (H7), respectively. K-1205-1 produced typical bipyramidal parasporal inclusions, but K-1381-1 produced irregular bipyramidal shape. Total plasmid DNA patterns analysis shewed that K-1205-1 and K- 1381-1 were different from their reference strains, subsp. kurstaki and subsp. aizawai, respectively, in high molecules, whereas their crystal protein patterns showed no difference. The cry gene contents of K-1205-1 and K-1381-1 were identical with those of the reference strains. Mosquitocidal activities of crystal proteins produced by K-1205-1 and K-1381-1 were significantly high by about 40-50 folds at $LC_50$ when compared to those of subsp. kurstaki and subsp. aizawai. Finally, in southern blot analysis using cry1A-type specific probe, K-1205-1 and K-1381-1 had different bands from subsp. kurstaki and subsp. aizawai, respectively. In conclusion, our results suggest that K-1205-1 and K-1381-1 appear to be new moquitocidal B. thuringiensis strains isolated from Korean soil.

• Earthquakes and Structures
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• v.1 no.1
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• pp.109-127
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• 2010

This work aims at introducing structural sensitivity analysis capabilities into existing commercial finite element software codes for the purpose of mapping retrofit strategies for a broad group of structures including heritage-type buildings. More specifically, the first stage sensitivity analysis is implemented for the standard deterministic environment, followed by stochastic structural sensitivity analysis defined for the probabilistic environment in a subsequent, second phase. It is believed that this new generation of software that will be released by the industrial partner will address the needs of a rapidly developing specialty within the engineering design profession, namely commercial retrofit and rehabilitation activities. In congested urban areas, these activities are carried out in reference to a certain percentage of the contemporary building stock that can no longer be demolished to give room for new construction because of economical, historical or cultural reasons. Furthermore, such analysis tools are becoming essential in reference to a new generation of national codes that spell out in detail how retrofit strategies ought to be implemented. More specifically, our work focuses on identifying the minimum-cost intervention on a given structure undergoing retrofit. Finally, an additional factor that arises in earthquake-prone regions across the world is the random nature of seismic activity that further complicates the task of determining the dynamic overstress that is being induced in the building stock and the additional demands placed on the supporting structural system.

• Journal of Power Electronics
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• v.15 no.3
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• pp.730-740
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• 2015

This paper presents model reference adaptive system speed estimators based on Type-1 and Type-2 fuzzy logic controllers for the speed sensorless direct torque and flux control of an induction motor drive (IMD) using space vector pulse width modulation. A Type-1 fuzzy logic controller (T1FLC) based adaptation mechanism scheme is initially presented to achieve high performance sensorless drive in both transient as well as in steady-state conditions. However, the Type-1 fuzzy sets are certain and cannot work effectively when a higher degree of uncertainties occurs in the system, which can be caused by sudden changes in speed or different load disturbances and, process noise. Therefore, a new Type-2 FLC (T2FLC) - based adaptation mechanism scheme is proposed to better handle the higher degree of uncertainties, improve the performance, and is also robust to different load torque and sudden changes in speed conditions. The detailed performance of different adaptation mechanism schemes are performed in a MATLAB/Simulink environment with a speed sensor and sensorless modes of operation when an IMD is operates under different operating conditions, such as no-load, load, and sudden changes in speed. To validate the different control approaches, the system is also implemented on a real-time system, and adequate results are reported for its validation.

• Journal of Chest Surgery
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• v.53 no.5
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• pp.285-290
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• 2020

Background: This study was conducted to evaluate the hemodynamic performance and the incidence of prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR) using bovine pericardial valves (Carpentier-Edwards Perimount Magana and Magna Ease). Methods: In total, 216 patients (mean age, 70.0±10.5 years) who underwent AVR using stented bovine pericardial valves and had follow-up echocardiography between 3 months and 2 years (mean, 12.0±6.6 months) after surgery were enrolled. The implanted valve sizes were 19, 21, 23, and 25 mm in 32, 56, 99, and 29 patients, respectively. Results: On follow-up echocardiography, the mean transvalvular pressure gradients for the 19-mm, 21-mm, 23-mm, and 25-mm valves were 13.3±4.4, 12.6±4.2, 10.5±3.9, and 10.2±3.7 mm Hg, respectively. The effective orifice area (EOA) was 1.25±0.26, 1.54±0.31, 1.81±0.41, and 1.87±0.33 ㎠, respectively. These values were smaller than those suggested by the manufacturer for the corresponding sizes. No patients had PPM, when based on the reference EOA. However, moderate (EOA index ≤0.85 ㎠/㎡) and severe (EOA index ≤0.65 ㎠/㎡) PPM was present in 56 patients (11.8%) and 9 patients (1.9%), respectively, when using the measured values. Conclusion: Carpentier-Edwards Perimount Magna and Magna Ease bovine pericardial valves showed satisfactory hemodynamic performance with low rates of PPM, although the reference EOA could overestimate the true EOA for individual patients.