• Computers and Concrete
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• 제21권2호
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• pp.199-207
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• 2018

With the development of concrete technology, producing concrete products that have the ability to flow under their own weights and do not need internal or external vibrations is an important achievement. In this study, assessments are made on using travertine, marble and limestone rock flours in self-compacting lightweight concrete (SCLC). In fact, the effects of these powders on plastic and hardened phases of SCLC are studied. To address this issue, concrete mixtures with water to cementitious materials ratios of 0.42 and 0.45 were used. These mixtures were made with 0 and 10% silica fume (SF) replacement levels by cement weight. To achieve lightweight concrete, lightweight expanded clay aggregate (Leca) with the bulk density of about $520kg/m^3 $was utilized. Also two kinds of water were consumed involving tap water and magnetic water (MW) for investigating the possible interaction of MW and rock flour type. In this study, 12 mixtures were studied, and their specific weights were in the range of $1660-1692kg/m^3$. To study the mixtures in plastic phase, tests such as slump flow, J-ring, V-funnel and U-box were performed. By using marble and travertine powders instead of limestone flour, the plastic viscosities and rheology were not changed considerably and they remained in the range of regulations. Moreover, SCLC showed better compressive strength with travertine, and then with marble rock flours compared to limestone powders. According to the results of the conducted study, MW showed better performance in both fresh and hardened phases in all the mixes, and there was no interaction between MW and rock flour type.

• Journal of the Korean School Mathematics Society
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• 제20권4호
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• pp.405-422
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• 2017

Nim games were divided into three stages : one file, two files and three files game, and inquiry activities were conducted for middle school mathematically gifted students. In the first stage, students easily found a winning strategy through deductive reasoning. In the second stage, students found a winning strategy with deductive reasoning or inductive reasoning, but found an error in inductive reasoning. In the third stage, no students found a winning strategy with deductive reasoning and errors were found in the induction reasoning process. It is found that the tendency to unconditionally generalize the pattern that is formed in the finite number of cases is the cause of the error. As a result of visually presenting the binary boxes to students, students were able to easily identify the pattern of victory and defeat, recognize the winning strategy through game activities, and some students could reach a stage of justifying the winning strategy.

• Advances in concrete construction
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• 제6권4호
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• pp.323-344
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• 2018

The study herein reports the impact of Steel Fiber (SF) and Ground Granulated Blast Furnaces slag (GGBFS) content on the fresh and hardened properties of fly ash (FA) based Self-Compacting Geopolymer Concrete (SCGC). Two series of self-compacting geopolymer concrete (SCGC) were formulated with a constant binder content of $450kg/m^3$ and at an alkaline-to-binder (a/b) ratio of 0.50. Fly ash (FA) was substituted with GGBFS with the replacement levels being 0%, 25%, 50%, 75%, and 100% by weight in each SCGC series. Steel fiber (SF) wasn't employed in the assembly of the initial concrete series whereas, within the second concrete series, an SF combination was achieved by a constant additional level of 1% by volume. Fresh properties of mixtures were through an experiment investigated in terms of slump flow diameter, T50 slump flow time, V-funnel flow time, and L-box height ratio. Moreover, the mechanical performance of the SCGCs was evaluated in terms of compressive strength, splitting tensile strength, and fracture toughness. Furthermore, a statistical analysis was applied in order to judge the importance of the experimental parameters, like GGBFS and SF contents. The experimental results indicated that the incorporation of SF had no vital impact on the fresh characteristics of the SCGC mixtures whereas GGBFS aggravated them. However, the incorporation of GGBFS was considerably improved the mechanical properties of SCGCs. Moreover, the incorporation of SF with the total different quantity of GGBFS replacement has considerably increased the mechanical properties of SCGCs, by close to (65%) for the splitting strength and (200%) for compressive strength.

• Journal of the Korean Institute of Landscape Architecture
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• 제38권5_2호
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• pp.186-193
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• 2010

The purpose of this study was to survey the citizens for their satisfaction with the outdoor landscape lighting in Gyeongju Historic Areas registered as UNESCO World Cultural Heritage in November 2000 and thereupon, provide for some basic data useful to the design of the outdoor landscape lighting for the cultural properties. As a result of examining the conditions of the outdoor landscape lighting in Wolseong Zone of Anapji, Banwolseong, Dongbu Sajeokji, Cheomseongdae and Gyerim, there were found 391 lighting fixtures of 12 types in Anapji, 138 lightings of 4 types in Banwolseong, 38 lightings of 6 types in Cheomseongdae, 28 lightings of 3 types in Dongbu Sajeokji and 54 lightings of 5 types in Gyerim. As a result of analyzing citizens' satisfaction with the outdoor landscape lighting, it was found that citizens were satisfied more or less with the nightscape image changed by the outdoor landscape lighting; their satisfaction scored 3.836 on average for Anapji on a 5-point Likert type scale, 3.516 for Banwolseong, 3.446 for Dongbu Sajeokji, 3.650 for Cheomseongdae and 3.479 for Gyerim. However, citizens' satisfaction with the originality of the nightscape was generally low: 3.055 for Anapji, 2.914 for Cheomseongdae, 2.877 for Banwolseong, 2.847 for Gyerim and 2.665 for Dongbu Sajeokji. On the other hand, since most of the lighting fixtures were installed as inserted lights or floodlights, the color tones of light source were relatively highly distinctive, but the peripheral spaces around the cultural properties were rather dark, which means that citizens were feeling inconvenient more or less for using the amenities such as bench or waste box. All in all, their satisfaction with the outdoor landscape at the sample zone at night scored 2.981, lower than the normal level.

• Cartoon and Animation Studies
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• 통권37호
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• pp.25-44
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• 2014

In the past 5 years, Chinese film market has witnessed a great development, with the film and animation box hitting records highs. At the same time, TV contents become more and more diverse, and the widespread use of smart phones makes Internet the new popular media today. On this occasion, domestic animation production is growing year by year because of people's growing demand for animation. And the volume of introduced foreign animations is growing as well. But under the same conditions, domestic animation shows obvious lack of competiveness. Chinese traditional stories have rich contents, providing a large amount of animation material. But most animations based on theses contents cannot arouse audiences' interests. This paper mainly analyzes the development situation of traditional story-based Chinese animation whose content is single and low-aged, and then put forward a new solution for Chinese animation development, which is, adding horror elements to traditional stories. And finally, through analyzing four horror animations , this paper further discusses the implementation possibility of this idea.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제39권12호
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• pp.1207-1212
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• 2015

A vibro ripper utilizes high-frequency vibration for rock fragmentation. This concept is different from those used by other existing breakers. The gearbox-shank welded joint of a vibro ripper is a very important part. Because it delivers the vibromotive force to the tooth, it is important to predict its soundness. This study was conducted to predict the fatigue life under welding conditions. The shank materials were Hardox-Hituf and AR400, and the filler metals were CSF-71T and CSF-81T. Fatigue tests were conducted under each set of conditions. P-S-N curves are presented based on the statistical testing method recommended by JSME-S002, and a comparison is made of the results under each set of conditions. The life was estimated using a P-S-N curve.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제20권9호
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• pp.1778-1784
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• 2016

we improved the performance by parallelizing lane detection algorithms. Lane detection, as a intellectual assisting system, helps drivers make an alarm sound or revise the handle in response of lane departure. Four kinds of algorithms are implemented in order as following, Gaussian filtering algorithm so as to remove the interferences, gray conversion algorithm to simplify images, sobel edge detection algorithm to find out the regions of lanes, and hough transform algorithm to detect straight lines. Among parallelized methods, the data level parallelism algorithm is easy to design, yet still problem with the bottleneck. The high-speed data level parallelism is suggested to reduce this bottleneck, which resulted in noticeable performance improvement. In the result of applying actual road video of black-box on our parallel algorithm, the measurement, in the case of single-core, is approximately 30 Frames/sec. Furthermore, in the case of octa-core parallelism, the data level performance is approximately 100 Frames/sec and the highest performance comes close to 150 Frames/sec.

• Journal of Oral Medicine and Pain
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• 제41권3호
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• pp.85-90
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• 2016

Purpose: The aim of this study was to develop an automated software to extract tooth and pulpal area from sectional cone-beam computed tomography (CBCT) images, which can guarantee more reproducible, objective and time-saving way to measure pulp/tooth volume ratio. Methods: The software program was developed using MATLAB (MathWorks). To determine the optimal threshold for the region of interest (ROI) extraction, user interface to adjust the threshold for extraction algorithm was added. Default threshold was determined after several trials to make the outline of extracted ROI fitting to the tooth and pulpal outlines. To test the effect of starting point location selected initially in the pulpal area on the final result, pulp/tooth volume ratio was calculated 5 times with different 5 starting points. Results: Navigation interface is composed of image loading, zoom-in, zoom-out, and move tool. ROI extraction process can be shown by check in the option box. Default threshold is adjusted for the extracted tooth area to cover whole tooth including dentin, cementum, and enamel. Of course, the result can be corrected, if necessary, by the examiner as well as by changing the threshold of density of hard tissue. Extracted tooth and pulp area are reconstructed three-dimensional (3D) and pulp/tooth volume ratio is calculated by voxel counting on reconstructed model. The difference between the pulp/tooth volume ratio results from the 5 different extraction starting points was not significant. Conclusions: In further studies based on a large-scale sample, the most proper threshold to present the most significant relationship between age and pulp/tooth volume ratio and the tooth correlated with age the most will be explored. If the software can be improved to use whole CBCT data set rather than just sectional images and to detect pulp canal in the original 3D images generated by CBCT software itself, it will be more promising in practical uses.

• Journal of Soil and Groundwater Environment
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• 제24권6호
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• pp.9-15
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• 2019

Soil dust emitted from large scale construction sites in urban areas has posed a significant health threats to local residents by exacerbating air quality. Water-spraying (moistening) is commonly practiced to lower the dust emission in construction sites, but its long term effectiveness is highly questionable. In this study, the utility of starch and PVA(polyvinyl alcohol) was investigated in suppression of the soil dust emissions in construction sites in Seoul areas. The efficiency of the two suppressants was tested with test soil sample in a lab-scale wind tunnel box under different concentrations of suppressants and soil textures. Starch and PVA showed the superior ability to suppress soil dust emission as compared to moistening, resulting in PM₁₀ and PM_2.5 lower than the daily limit values of 30 and 15 ㎍/㎥ respectively. PVA showed higher suppression capability than starch for all conditions. The test soils mixed with suppressants also showed dramatically enhanced aggregate stability compared to the non-treated soil.

• Journal of Applied Reliability
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• 제14권4호
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• pp.213-219
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• 2014

Wind turbine, which is attracting part of the renewable energy and is researching continuously, is going to be large size for high efficiency. There is a yaw system rotating the nacelle, weighted about 600 tons, to be perpendicular with the wind direction blowing in the large wind turbine. The wind turbine is focusing on the reliability improvement because working environment effect is bigger than any other points and specially, the reliability improvement of the yaw drive is required by the customer because it is the key component of the wind turbine. Because of this, the establishment of criteria for yaw drive is required because yaw drive system is the part of the wind turbine closely related with ensuring the reliability. So, this study did the failure analysis of the yaw drive system, which is consisted with 10 sets of yaw drives through researching and analyzing the site conditions. Also this study designed the life test method based on the failure analysis and working condition of the yaw drive. To design the accelerated life test of the yaw drive, this study reviewed the torque, lubrication condition, and frequency of use and etc. Finally, this selected the torque as the acceleration factor which is affected mainly to the system and also, the test equipment was developed based on the requirement of the life and performance test.