• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2153-2166
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• 2017

Web apps have a problem that they cause same data to be repetitively retrieved, processed, and displayed when web browsers load different web pages. To resolve the problem, this paper presents and evaluates a new method for restructuring of Java web apps. This approach dynamically analyzes Java web apps from the MVC (Model-View-Controller) architecture point of view and identifies redundant data by using the composite view pattern. Then the input apps are restructured in order not to load the redundant data when users make requests for new pages. This restructuring generates new web apps that conform to the MVC architecture and improve the performance of input web apps. The experimental results showed that when compared to legacy web apps, the restructured apps' response time was reduced on desktop PCs and mobile devices by 38% and 55%, respectively. In addition, case studies using open-source web apps showed the applicability of the proposed approach.

• Structural Monitoring and Maintenance
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• v.5 no.2
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• pp.243-260
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• 2018

Detection of damages in fibre reinforced plastic (FRP) composite structures is important from the safety and serviceability point of view. Usually, damage is realized as a local reduction of stiffness and if dynamic responses of the structure are sensitive enough to such changes in stiffness, then a well posed inverse problem can provide an efficient solution to the damage detection problem. Usually, such inverse problems are solved within the framework of pattern recognition. Support Vector Machine (SVM) Algorithm is one such methodology, which minimizes the weighted differences between the experimentally observed dynamic responses and those computed using the finite element model- by optimizing appropriately chosen parameters, such as stiffness. A damage detection strategy is hereby proposed using SVM which perform stepwise by first locating and then determining the severity of the damage. The SVM algorithm uses simulations of only a limited number of damage scenarios and trains the algorithm in such a way so as to detect damages at unknown locations by recognizing the pattern of changes in dynamic responses. A rectangular fiber reinforced plastic composite plate has been investigated both numerically and experimentally to observe the efficiency of the SVM algorithm for damage detection. Experimentally determined modal responses, such as natural frequencies and mode shapes are used as observable parameters. The results are encouraging since a high percentage of damage cases have been successfully determined using the proposed algorithm.

• KIEAE Journal
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• v.10 no.1
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• pp.97-107
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• 2010

Although aspiration towards quality of life and holistic health has been growing faster in our modern society and the affordance of health in built environment has been more acknowledged, there has been hardly any development on built environment planning and design theory that can be comfortably and confidently used in creating built environment to promote holistic health. Thereby, this study sets out to experimently formulate a composite theory that explains the relationship between health and built environment. The main methodology of this study is literature review and analysis. Theories that have been applied in other similar fields were chosen to be analyzed by health related perspectives and graft those theories onto holistic health viewpoints to compose a comprehensive theory. Selected theories that were considered useful to be analyzed were Lawton's Environment Press Theory, Carp & Carp's Complementary & Congruence Theory, Valins' Activity-based Design Criteria Theory, Atchley's Continuity Theory, Murtha & Lee's User Benefit Criteria Theory, and Alexander's Pattern Language Theory. Characteristics of these theories were compared by their abstractness and concreteness, and the range of application, and analyzed by a holistic health perspective. Then, these theories were comprehensively structuralized and synthesized as a built environment for health theory. This study has its significance in providing a base to develop healthy built environment research further as it introduced a conceptual framework which explains spatial elements in the health functionality point of view.

• Advanced Composite Materials
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• v.17 no.3
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• pp.225-233
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• 2008

The analysis in this paper is focused on the pattern of mixing of filaments over a cross-section of hybrid yarns according to different combinations of reinforcement and matrix filament yarns through microscopic view. The volume content of filament in hybrid yarn cross-section was maintained at 50% for both reinforcement and matrix, and the hybrid yarns count at 600 tex throughout the experiments. It was observed from the experiments that diameters of reinforcement and matrix filaments have strong effects particularly on the pattern of mixing of filaments over a cross-section of hybrid yarns such that the hybrid yarns with more or less equal diameters of reinforcement and matrix filaments showed considerably even distributions over the hybrid yarn cross-section. This paper also investigates the possibility of hybridizing carbon/aramid, carbon/glass and aramid/glass matrices through the commingling process. In the experiment, several process parameters were selected and they include pressure, yarn oversupply-rate and different nozzle types. As a result of these experiments, it was concluded that the hybridized materials show better performance than individual reinforced filament yarns in terms of mechanical properties. For small tensile forces, the carbon/glass/matrix combination turned out to be good enough for general purpose applications.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.292-295
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• 2004

Recently, polymer-clay hybrid materials have received considerable attention from both a fundamental research and application point of view. This organ-inorganic hybrid, which contains a nanoscale dispersion of the layered silicates, is a material with greatly improved thermal and mechanical characteristics. Two classes of nanocomposites were synthesized using an unsaturated polyester resin as the matrix and sodium montmorillonite as well as an organically modified montmorillonite as the reinforcing agents. X -ray diffraction pattern of the composites showed that the interlayer spacing of the modified montmorillonite were exfoliated in polymer matrix. The mechanical properties also supported these findings, since in general, tensile strength, modulus with modified montmorillonite were higher than the corresponding properties of the composites with unmodified montmorillonite. Adding organically modified clay improved the tensile strength of unsaturated polyester by $22\%$ and the tensile modulus of unsaturated polyester was also improved by $34\%$.

• Fire Science and Engineering
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• v.27 no.2
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• pp.25-30
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• 2013

'Heaundae Woosin Building' fire was the case that a fire breaking out on the $4^{th}$ floor spread out the $38^{th}$ floor which is a top story and the penthouse was destroyed by fire. After this fire, the fire safety for high rise buildings has been on the rise and several new laws and regulations related in the buildings were created. The study is to analyze Heaundae officetel building case using FDS which is one of the CFD programs for fire. The methodology of this study is to analyze the case comparing with fire spread and route from a virtual fire simulation and related articles and a video clip of actual scene fire. This study shows that a fire spreading on top of levels spent approximately 30 minutes and, which is similar to the actual fire case. Also the pattern of spread has similarity with the case. However, even if the actual fire case shows the fire pattern was "V shape", the smoke-view presents the fire dose not spread horizontally as much as the real fire case. The result shows uncertainty of the modeling based on many grids and a limitation of putting interior finish input sources and the direction of the wind might cause the difference. Also, to analyze factors influencing on a vertical fire, another fire modeling is performed by in condition of modeling environment considering concrete interior finish between buildings and no wind. The result presents the fire spread in smoke-view does not spread vertically as much as the actual case.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.465-469
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• 2008

Mobile phone becomes composite product which the high technological multimedia functions of a Digital camera, MP3, MP4, Blue-tooth, DMB over basic functions of a calling and 3M3. By the view of user, many functions give a heavy burden rather than supporting convenient function itself because it is complex for user to use it. We want to evaluate how users feel using mobile phone according to age, comparing use frequency and necessity. So survey is tried to figure out the difference between use frequency and necessity by dividing three groups into 20s and 30s and 50s. As a result, difference of use frequency and necessity for functions of mobile phone between 20s and 30s and 50s. And the other users have the difference. Consequently, mobile phone development according to age is necessary to satisfy user's desire, evaluating elements research of user preference. We hope this paper can contribute to mobile phone development as a basic guidance.