• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.8 s.99
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• pp.835-841
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• 2005

In this paper, a novel sized-reduced CPW(Coplanar Waveguide) balun is proposed. It has a crossing structure between signal line and ground planes of CPW transmission line for the $180^{\circ}$ phase inversion. The$3{\lambda}/4$ CPW transmission line is reduced to ${\lambda}/4$ in physical length while the electrical length is preserved to $270^{\circ}$ by the $180^{\circ}$ phase inverting structure, while the previous balun by Lim et at. has a long $3{\lambda}/4$ transmission section to from the Wilkinson divider structure having out of phase between output ports. In addition, the measured data which show the crossing structure has the wanted $180^{\circ}$ phase change is presented in this work.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.623-636
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• 2012

Roundabout is an intersection that allows vehicles to pass through the intersection by circulating the circular traffic island at the center of the intersection. In this study, a comparative analysis was conducted on roundabout at five locations in order to deduce the operational result and financial effect of roundabout and signal intersection. As for the operational result, it was found that roundabout showed improvement effect in the average delay per vehicle compared to that of signal intersection by minimum of 65.6% and maximum of 91.77%. it was found that roundabout showed financial cost-saving effect in the traffic congestion cost compared to that of signal operation by minimum of 58.59% and maximum of 81.69% per year. It can be known from these analysis results that roundabout has significant operational effects under certain amount of traffic volume by allowing vehicles to pass through the intersection in a continuous way without much waiting time and stoppage from signal control.

• Korean Journal of Remote Sensing
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• v.34 no.5
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• pp.777-786
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• 2018

GF (Guided Filtering) is a representative image processing technique to effectively remove noise while preserving edge information in the digital image. In this paper, we proposed a unsupervised change detection method for the KOMPSAT-3 satellite image using the GF and evaluated its performance. In order to utilize GF for the unsupervised change detection, cross-sharpened images were generated based on GF, and CVA (Change Vector Analysis) was applied to the generated cross-sharpened images to extract the changed area in the multitemporal satellite imagery. Experimental results using KOMPSAT-3 satellite images showed that the proposed method can be effectively used to detect changed regions compared with CVA results based on existing cross-sharpened images.

• Journal of Korean Society of Transportation
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• v.27 no.3
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• pp.91-102
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• 2009

A traffic accident prediction model developed using various design variables(road design variables, geometric variables, and traffic environmental variables) is one of the most important factors to safety design evaluation system for roads. However, statistical accident models have a crucial problem not applicable for all intersections. To make up this problem, this study developed AMFs(Accident Modification Factors) through statistical modeling methods, historical accident databases, judgment from traffic experts, and literature review by considering design variable's characteristics, traffic accident rates, and traffic accident frequency. AMFs developed in this study include exclusive left-turn lane, exclusive right-turn lane, sight distance, and intersection angle. Predictabilities of the developed AMFs and the existing accident prediction models are compared with real accident historical data. The results showed that performances of the developed AMFs are superior to the existing statistical accident prediction models. These findings show that AMFs should be considered as a important process to develop safety design evaluation algorithms. Additionally, AMFs could be used as an index that can judge the impact of corresponding design variables on accidents in rural intersections.

• The KIPS Transactions:PartB
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• v.11B no.1
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• pp.7-12
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• 2004

This thesis studies about thinning compensation and the removal of pseudo minutiae using ridge trace. As for the process of thinning compensation, first, it removes unnecessary pixel when 8-neighbor connection sum among the pixels with the crossing count number 6 is not 3. Second, it deals with repeatedly until there is no pixel to remove while tracing the ridge, beginning with the pixel equivalent to the ridge and the pixel with the crossing count number 2 among the 8 pixels around the pixels with the crossing count number 6. When the thinning compensation is finished, it extracts substitute minutiae to use the crossing count number and the 8-neighbor connection sum. Among the extracted substitute minutiaes, it extracts the real minutiae to utilize the pseudo minutiae removal algorithm again. It compares with the existing method for the performance evaluation of proposal method. By the experimental results, The proposal method indicated that a degree of thinning is excellent and a lot of minutiaes were removed.

• Journal of Korean Society of Transportation
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• v.19 no.2
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• pp.21-28
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• 2001

This study is to estimate the through car equivalent for left-turn movement according to left turn radius in the signalized intersection. The saturation flow rate for left-turn movement in 92' KHCM(Korea Highway Capacity Manual) is the same as that for through movement in the signalized intersection where the left turn radius is over 20m. This study uses Duncan 'Test's Test in order to find out the saturated position for queued vehicle in the signalized intersection. It found that the saturated flow rate of left-turn movement in the signalized intersection is less than that of through movement where the left-turn radius is less than 20m. It found that the through car equivalents for left-turn movement according to left-turn radius(8m-20m) are between 1.05 and 1.14.

• Journal of Satellite, Information and Communications
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• v.8 no.3
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• pp.52-57
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• 2013

This paper describes the color comparison analysis of flame in each standard color model in order to propose the optimal color model for image processing based flame detection algorithm. Histogram intersection values were used to analyze the separation characteristics between color of flame and color of non-flame in each standard color model which are RGB, YCbCr, CIE Lab, HSV. Histogram intersection value in each color model and components is evaluated for objective comparison. The analyzed result shows that YCbCr color model is the most suitable for flame detection by average HI value of 0.0575. Among the 12 components of standard color models, each Cb, R, Cr component has respectively HI value of 0.0433, 0.0526, 0.0567 and they have shown the best flame separation characteristics.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.2
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• pp.177-185
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• 2010

Ray-object intersection is an important element in ray tracing that takes up a substantial amount of computing time. In general, such spatial data structure as kd-tree has been frequently used for static scenes to accelerate the intersection computation. Recently, a few variants of kd-tree traversal have been proposed suitable for the GPU that has a relatively restricted computing architecture compared to the CPU. In this article, we propose yet another two implementation techniques that can improve those previous ones. First, we present a cached stack method that is aimed to reduce the costly global memory access time needed when the stack is allocated to global memory. Secondly, we present a rope-with-short-stack method that eases the substantial memory requirement, often necessary for the previous rope method. In order to show the effectiveness of our techniques, we compare their performances with those of the previous GPU traversal methods. The experimental results will provide prospective GPU ray tracer developers with valuable information, helping them choose a proper kd-tree traversal method.

• Communications of Mathematical Education
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• v.25 no.4
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• pp.629-639
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• 2011

Currently science and technology are changing so fast and college mathematics becomes more and more important. But the downturn of freshmen's scholastic performance has been intensified and this phenomenon leads to serious problems in managing college curriculums. During the recent years at a middle level engineering college, many freshmen had a lot of difficulties in their mathematics courses. In consequence, many of them had hard time to survive at their major curriculums. In this point of view, we analyse the situation of mathematical scholastic ability among engineering majored freshmen through the research on the actual state of mathematical background, mathematical scholastic ability test, college mathematics scores, and scholastic aptitude test scores. We study the relation between the mathematics score of scholastic aptitude test for the college entrance and mathematical scholastic ability of freshmen of a middle level engineering college. From this study we conclude that the essential reasons for the above situations are the curriculum of middle school mathematics and the system of scholastic aptitude test and the entrance examination of university. In order for improving mathematical accomplishment. we give suggestions such as a learning ability improvement program in mathematics.

• Journal of the Korean Data and Information Science Society
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• v.27 no.5
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• pp.1263-1272
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• 2016

Product array approach which is used in the Taguchi parameter design has a number of advantages by considering the noise factor. However, a disadvantage of this method is that it requires an excessively large number of experiments. So combined array approach have been proposed to reduce the number of experiments. Taguchi has used the signal-to-noise ratio to find the optimum conditions in the Taguchi parameter design. In analyzing the data from the parameter design various problems tends occur by using an SN. In this paper, we propose an alternative solution for reducing the number of experiments without depending on the signal-to-noise ratio to overcome the shortcomings of the parameter design. Two examples illustrate this procedure in the two different experimental design (product array, combined array) approaches.