• Journal of Power System Engineering
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• v.22 no.1
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• pp.48-55
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• 2018

It has recently been reported that methanol fuel has been used in the product carrier with established duel fuel engine, which has been greatly reducing emissions of $CO_2$, NOx and SOx from the engine. However, to use methanol alone as fuel oil in a general diesel engine, design modification of cylinder head is needed because the ignition aid device or the duel fuel injection system is needed. On the other hand, only if the mixer is installed on the fuel oil supply line, diesel oil - methanol blending oil can be used as fuel oil for the diesel engine, but there is a problem of the phase separation when two fuels are mixed. In this study, diesel oil and methanol were blended compulsorily in preventing the phase separation with installing agitators and a fuel oil boost pump on fuel line of a test engine. Also, cylinder pressure and fuel consumption quantity were measured according to engine load and methanol blending ratio, and indicated mean effective pressure, heat release rate and combustion temperature obtained from the single zone combustion model were analyzed to investigate the effects of latent heat of vaporization of methanol on combustion stability and characteristics. As a result, the combustion stability and characteristics of 10% methanol blending oil are closest to the those of diesel oil, and it could be used as fuel oil in existing diesel engines without deterioration of engine performance and combustion characteristics.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.87-94
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• 2014

In solid mechanics, the peridynamics theory has provided a suitable framework for material failure and damage propagation simulation. Peridynamics is computationally expensive since it is required to solve enormous nonlocal interactions based upon integro-differential equations. Thus, multiscale coupling methods with other local models are of interest for efficient and accurate implementations of peridynamics. In this study, peridynamic models are restricted to regions where discontinuities or stress concentrations are present. In the domains characterized by smooth displacements, classical local models can be employed. We introduce a recently developed blending scheme to concurrently couple bond-based peridynamic models and the Navier equation of classical elasticity. We demonstrate numerically that the proposed blended model is suitable for point loads and static fracture, suggesting an alternative framework for cases where peridynamic models are too expensive, while classical local models are not accurate enough.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.55-67
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• 2020

The common practice to predict the characteristic structural load effects (LEs) in long reference periods is to employ the extreme value theory (EVT) for building limit distributions. However, most applications ignore that LEs are driven by multiple loading events and thus do not have the identical distribution, a prerequisite for EVT. In this study, we propose the composite extreme value modeling approach using clustering to (a) cluster initial blended samples into finite identical distributed subsamples using the finite mixture model, expectation-maximization algorithm, and the Akaike information criterion; (b) combine limit distributions of subsamples into a composite prediction equation using the generalized Pareto distribution based on a joint threshold. The proposed approach was validated both through numerical examples with known solutions and engineering applications of bridge traffic LEs on a long-span bridge. The results indicate that a joint threshold largely benefits the composite extreme value modeling, many appropriate tail approaching models can be used, and the equation form is simply the sum of the weighted models. In numerical examples, the proposed approach using clustering generated accurate extrema prediction of any reference period compared with the known solutions, whereas the common practice of employing EVT without clustering on the mixture data showed large deviations. Real-world bridge traffic LEs are driven by multi-events and present multipeak distributions, and the proposed approach is more capable of capturing the tendency of tailed LEs than the conventional approach. The proposed approach is expected to have wide applications to general problems such as samples that are driven by multiple events and that do not have the identical distribution.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.3 s.303
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• pp.63-72
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• 2005

In this paper, we propose a deformation technique based on Radial Basis Function (RBF) and a blending technique combining the deformed facial component with the original face for a Virtual Aesthetic Surgery (VAS) system. The deformation technique needs the smoothness and the accuracy to deform the fluid facial components and also needs the locality not to affect or distort the rest of the facial components besides the deformation region. To satisfy these deformation characteristics, The VAS System computes the degree of deformation of lattice cells using RBF based on a Free-Form Deformation (FFD) model. The deformation error is compensated by the coefficients of mapping function, which is recursively solved by the Singular Value Decomposition (SVD) technique using SSE (Sum of Squared Error) between the deformed control points and target control points on base curves. The deformed facial component is blended with an original face using a blending ratio that is computed by the Euclidean distance transform. An experimental result shows that the proposed deformation and blending techniques are very efficient in terms of accuracy and distortion.

• Convergence Security Journal
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• v.11 no.1
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• pp.39-48
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• 2011

QoS(Quality of Service) is defined "The collective effect of service performance which determines the degree of satisfaction of a user of the service" by ITU-T Rec. E.800. The final goal of information system is to secure the performance efficiency within the required time. The security QoS framework is the modeling of the QoS measurement metrics, the measurement time schedule, instrument, method of measurement and the series of methodology about analysis of the result of measurement. This paper relates to implementing issue and performance measuring about blended mechanism between networking technology and security technology. We got more effectiveness in overall network security, when applying and composing amalgamated security mechanism between network technology and security technology. In this paper, we suggest techniques being used on infrastructure system and also offers a security QoS methodology as a model of more effective way. Methodology proposed in this research has proven that it is possible to measure response time through the scheduled method.

• Journal of The Korean Association of Information Education
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• v.25 no.4
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• pp.621-632
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• 2021

This study is about development and application of a curriculum to implement physical computing education in an online environment for pre-service teachers. First, a 15-week software and physical computing curriculum was designed according to the ADDIE instructional design model. As a tool that can be used online, education was conducted on a program using various sensors using Pocket Code, an EPL based on a smartphone. As a result of the application of the program, Personal efficacy, Pedagogical knowledge, Technology teaching content knowledge, Result expectation, and Student belief were all significantly improved. In the software attitude part, Software interest and Software value part increased significantly, and the Perception of software engineers did not change. In general, in the case of physical computing, it is difficult to execute in an online environment because it involves a lot of manipulation activity. Through various studies that can continue education in a non-face-to-face environment or a blended environment in the post-corona era, it is hoped that it will be possible to provide a high-quality curriculum to pre-service teachers in charge of future education.

• Journal of Korean Society of Disaster and Security
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• v.11 no.2
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• pp.75-82
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• 2018

The purpose of this study is designed to apply the model of the problem-based learning in the class of Disaster Psychology and then analyze the experiences that its students felt. The participants in this research are 56 undergraduates. The class of Disaster Psychology was conducted with blended learning using lecture and PBL. The PBL problem should be solved just for 3 weeks. The data collected after the class is an analysis of the PBL problem, log on group activities, personal reflection diary, Group evaluation. Then, each data should be collected and analyzed quantitatively through the repetitive comparison, and the triangle-measurement. The findings suggest that there is a remarkable educational learning experience in seven categories: acquire expertise, confidence, practical problem-solving skill, communication ability, roles of calling, efficacy, change in perspective. This study introduces a case of PBL course development and expects subsequent applications and research.

• Journal of The Korean Association of Information Education
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• v.25 no.3
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• pp.579-590
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• 2021

This study examined the mediating effect of learning engagement in the relationship between self-regulation, teaching presence and computational thinking in online SW education. To verify the research problem, a blended learning model adopted SW liberal course at A Women's University located in Seoul, which 94 students were enrolled in, was selected. The results of this study and the implications are as follows: First, it was found that learning engagement mediated the relationship between self-regulation and computational thinking. Second, it was found that learning engagement mediated the relationship between teaching presence and computational thinking. This study suggested a plan to improve learners' active engagement and self-regulation strategy in online SW education. In addition, it is significant that this study considered a method for learners to perceive teaching presence in online learning environment.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.83-91
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• 2020

The purpose of this study is to develop creativity-based creative convergence subjects for nursing students. For the purpose of this study, the procedures are conducted that the needs analysis, setting educational goals, segmentation of educational goals, selection of educational contents and organization by F. Bobbitt's curriculum development model and the creative convergence subject was developed through the verification process of the validity of experts. Through a theoretical review, the contents of education in creative convergence subjects consisted of converging with other areas, focusing on creativity. It was presented as a liberal arts subject with two credits, and as an educational method, an online class utilizing blended learning and offline classes centered on activities by teams were presented. In addition, the curriculum was divided into understanding, application, synthesis, and deepening so that students could understand the concept of creative convergence thinking and apply it through thinking techniques and strategies, and finally improve their creative convergence thinking abilities through team projects.

• Journal of Practical Engineering Education
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• v.14 no.1
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• pp.109-118
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• 2022

The purpose of this study is to derive implications for establishing vocational training education policies in Korea by investigating COVID-19 countermeasures in the United States, Germany, Switzerland, Australia, the United Kingdom, and Singapore, which are representative vocational education training countries. The implications derived from the survey of leading countries in vocational education training are as follows. First, in order to respond to COVID-19, face-to-face vocational education training was quickly converted to online education. Second, the system was strengthened to overcome the crisis of the apprenticeship system, especially the British and Australian governments established a special budget for the apprenticeship system. Third, due to COVID-19, blended learning has become a new standard education model, accelerating the digitalization of vocational education training. Finally, leading countries in vocational education training are promoting the development of the edutech industry to support online education. This provides important implications for the direction of change in vocational education training in South Korea.