• Journal of Korea Foundry Society
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• v.18 no.5
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• pp.431-438
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• 1998

Microstructure of A356 aluminum alloys cast in the permanent mold was investigated by optical microscope and image analyzer, with particular respect to the shape and size distribution of iron intermetallics known as ${\beta}-phase$ ($Al_5FeSi$). Morphologies of the ${\beta}-phase$ was found to change gradually with the Be:Fe ratio like these. In Be-free alloys, ${\beta}-phase$ with needlelike morphology was well developed, but script phase was appeared when the Be:Fe ratio is above 0.2:1. With the Be:Fe ratios of 0.4:1-1:1, script phase as well as Be-rich phase was also observed. In case of higher Be addition, above 1:1, Be-rich phase was observed on all regions of the specimens, and increasing of the Be:Fe ratios gradually make the Be-rich phase coarse. It was also observed that the ${\beta}-phase$ with needlelike morphology was coarsened with increase of the Fe content in Be-free alloys. However, in Be-added alloys, length and number of these ${\beta}-phases$ were considerably decreased with the increased Be:Fe ratio. Beryllium addition improved tensile properties and impact toughness of the A356 aluminium alloy, due to the formation of a script phase or a Be-rich phase instead of a needlelike ${\beta}-phase$. The DSC tests indicated that the presence of Be could increase the amount of Mg which is available for $Mg_2Si$ precipitate hardening, and enhance the precipitation kinetics by lowering the ternary eutectic temperature.

• Architectural research
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• v.18 no.1
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• pp.1-12
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• 2016

This thesis explores Vitruvius and his impact upon other Renaissance architects who compare a city to a building or a building to a city, who match the city and the building into a human body, and who develop their own works. The objective of this study is to furnish an interpretation of their theory and practice through their literature and designs. In this point of view, this article takes notice of Vitruvius's six concepts coined from venustas and divides them into two parts: i.e. aesthetic quality (ordinatio, dispositio, and distributio) and technical activity (eurythmia, symmetria, and $d{\acute{e}}cor$) each. This thesis indicates that Vitruvius's successive impacts from the concepts bring about concrete design principles through proportional measurements, placing together, and hierarchic values for the former, as well as appropriate use through beautiful look, symmetrical harmony, and appropriate uses for the latter, tracking notions between a city as a house and vice versa, and either the ideas of the house or the city in the synthesis of the human body, which follows the perfect number and module based on the human body. The thesis shows that the representations of architecture and the city take place with the form of a circle and a square that express the religious belief and the cosmos, substantiating the connection between the proportions of the human body and numbers, and ultimately satisfying a concept of centrality, which is slowly extended to the enclosed plaza at the urban level from chambers, atrium, and corridors at the residence level.

• Journal of Service Research and Studies
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• v.6 no.2
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• pp.37-49
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• 2016

Due to the expandability of smartphone, the mobile application market is growing explosively. However, as happens in other digital contents markets, piracy of mobile applications is prevalent. This study investigated the effects of behavioral factors on smartphone application piracy. The research model consists of factors from the theory of planned behavior model - subjective norms, attitudes toward piracy and perceptions of behavioral control. In addition, perceived consequences, past behavior and habit was included. The past behavior of PC software piracy was a meaningful predictor of habit, and habit was found to influence significantly the smartphone piracy intention. The result also shows that perceived benefit had significant effect on attitude, but both perceived legal and technical risk were not significantly related to attitude. Implications for research and practice are discussed.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.7-17
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• 2014

This technical paper deals with development of on-board orbit generation algorithm for GEO Satellite. This paper presents the research analysis results performed in order to improve the accuracy of the existing algorithm used for generating real-time orbit information for GEO satellite. The error impact on orbit accuracy due to the orbit error sources were analyzed with the algorithm suggested by this research. As a result of the analyses, it is found that the initial orbit should be determined with an accuracy of less than 50 m and the reference position angle error for the ground station and the satellite should be maintained within ${\pm}0.0025deg$ in order to meet the orbit accuracy specification. The development of on-board flight software based on the new algorithm was accomplished and the performance verification is ongoing by using a software based performance verification tool.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.40-50
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• 2012

Face recognition is a biometric technology used to identify individuals based on facial feature information. Previous studies of face recognition used features including the eye, mouth and nose; however, there have been few studies on the effects of using other facial components, such as the eyebrows and chin, on recognition performance. We measured the recognition accuracy affected by these facial components, and compared the differences between computer-based and human-based facial recognition methods. This research is novel in the following four ways compared to previous works. First, we measured the effect of components such as the eyebrows and chin. And the accuracy of computer-based face recognition was compared to human-based face recognition according to facial components. Second, for computer-based recognition, facial components were automatically detected using the Adaboost algorithm and active appearance model (AAM), and user authentication was achieved with the face recognition algorithm based on principal component analysis (PCA). Third, we experimentally proved that the number of facial features (when including eyebrows, eye, nose, mouth, and chin) had a greater impact on the accuracy of human-based face recognition, but consistent inclusion of some feature such as chin area had more influence on the accuracy of computer-based face recognition because a computer uses the pixel values of facial images in classifying faces. Fourth, we experimentally proved that the eyebrow feature enhanced the accuracy of computer-based face recognition. However, the problem of occlusion by hair should be solved in order to use the eyebrow feature for face recognition.

• International Journal of High-Rise Buildings
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• v.2 no.1
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• pp.49-62
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• 2013

Many previous tall building fires demonstrate that despite code compliant construction fires often spread vertically and burn over multiple floors at the same time. The collapses of the WTC complex buildings in 9/11 as well as other partial collapses like the ones of the Windsor Tower in Madrid and of the Technical University of Delft building posed new questions on the stability of tall buildings in fire. These accidents have shown that local or global collapse is possible in multi-floor fires. In most of the previous work involving multi-floor fires all floors were assumed to be heated simultaneously although in reality fires travel from one floor to another. This paper extends previous research by focusing on the collapse mechanisms of tall buildings in fire and performs a parametric study using various travelling rates. The results of the study demonstrate that vertically travelling fires have beneficial impact in terms of the global structural response of tall buildings in comparison to simultaneous fires. Contrary to the beneficial effect of the travelling fires in terms of the global structural response, it was noticed that higher tensile forces were also present in the floors compared to simultaneous multi-floor case. Designers are therefore advised to consider simultaneous multi-floor fire as an upper bound scenario. However, a scenario where a travelling fire is used is also suggested to be examined, as the tensile capacity of connections may be underestimated.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.407-414
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• 2016

The movie, X-men, develops the narrative with metamorphosis as the main motif making visual effects of characters and background. The objective of this study is to suggest that the metamorphosis motif can be materialized based on the virtuality of "pataphysics" as one of the genre characteristics of superhero movies and the newly materialized virtuality can be aesthetic characteristics of metamorphosis motif movies. With the virtuality that has its own characteristics with metaphorical symbols such as satire on an absurd society out of existing traditions, pataphysics started in mid-twentieth century and has had an impact on art movements of dadaism, surrealism, pop art, and postmodernism. Analyzing the characteristics of pataphysics which were shown in these artworks, we applied it to metamorphosis scenes of the movie. As a result, we found out that it visualized the shape and aspect of inner and outer strength of a superhero with aesthetic characteristics of metamorphosis scenes and it realized the presence, hybridity, and ex-formal properties of pataphysics consisting of overlapped virtual and physical reality, with technical virtuality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4977-4983
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• 2015

The full depth excavation induces couple of technical and social problems like increase of construction cost and time for excavation and backfill, increase of public complains and delay of traffic, and so force. In order to overcome these problems, lots of laboratory tests were carried out for sewer pipeline of maintenance materials with trenchless methods. The testing materials are PVC strip and then the lab tests were followed by Korean Standard. We will treat the structure safety and pipe integrity of PVC profile more excellent than the profile have application to SPR. There is no side-effect to process and to satisfy the criteria of tensile strength, impact strength and softening temperature. The profile with resin adhesive showed no leakage of water at specific pressure.

• The Journal of Korean Association of Computer Education
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• v.23 no.3
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• pp.59-64
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• 2020

This study conducted a 15-week experiment on 236 students who took a major in engineering to find out the impact of learning through flipped learning on their academic performance. Previous flipped learning studies have largely been tested on learning motivation or learning satisfaction through questionnaires, and few have compared academic performance differences. Therefore, it is necessary to identify the increase and decrease in academic performance in the flipped learning classroom. Studies have shown significant differences that is a big difference between the academic performance of the experimental group appling flipped learning and the control group appling traditional lecture-style classes, and the academic performance of the experimental group was higher than that of the control group. This can be said to have a positive effect on academic performance. Therefore, it is hoped that the flip learning method will be expanded in all curriculums.

• Journal of radiological science and technology
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• v.16 no.1
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• pp.89-94
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• 1993

However, technical advances in ultrasono imaging have had a remarkable impact on the study of biliary system oral cholecystography is a contrast of the gallbladder which is very frequently performed even with the application of Extra Shock Wave Lithotripsy(ESWL) in clinical use. Oral GB requires a stringent preparation if it is to be fully successful and a considerable amount of time to complete all its procedures and its objects of the radiographs. 1) to obtain a firm diagnosis of the presence of gallstones. 2) to essess function of the gallbladder that is, its ability to concentrate and store bile. After a times sequence of X-ray exposures taken in various positions to show the gallbladder to be satisfactorily filled, the patient is given a fatty meal, for instances two eggs or a cup of milk. The gallbladder which is drained by the cystic duct stores and concentrates the bile and is stimulated to contrast and excrete the bile by hormone "cholecystokinin" secreted in the intestinal mucosa. To evaluate the effect of the fatty meal which caused the gallbladder to constrict and empty, and by so doing the contrast medium passes through the cystic and bile ducts which are shown in radiographs exposed from 15-30 minutes after the variety practice of fattymeal, such as soft-boiled 2 eggs, raw 2 eggs, 100g of peanuts, and 200ml of milk. If the concentration of the opaque medium in the gallbladder is adequate, then not only the size, shape and position of the gallbladder will be shown from firms taken at intervals, the rate of concentration of the opaque medium and of the emptying of gallbladder has been measured and analyzed.