• Genomics & Informatics
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• v.8 no.3
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• pp.150-158
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• 2010

Genome-wise association studies (GWASs) have become popular approaches to identify genetic variants associated with human biological traits. In this study, we applied Structural Equation Models (SEMs) in order to model complex relationships between genetic networks and traits as risk factors. SEMs allow us to achieve a better understanding of biological mechanisms through identifying greater numbers of genes and pathways that are associated with a set of traits and the relationship among them. For efficient SEM analysis for GWASs, we developed a procedure, comprised of four stages. In the first stage, we conducted single-SNP analysis using regression models, where age, sex, and recruited area were included as adjusting covariates. In the second stage, Fisher's combination test was conducted for each gene to detect significant genes using p-values obtained from the single-SNP analysis. In the third stage, Fisher's exact test was adopted to determine which biological pathways were enriched with significant SNPs. Finally, based on a pathway that was associated with the four traits in common, a SEM was fit to model a causal relationship among the genetic factors and traits. We applied our SEM model to GWAS data with four central obesity related traits: suprailiac and subscapular measures for upper body fat, BMI, and hypertension. Study subjects were collected from two Korean cohort regions. After quality control, 327,872 SNPs for 8842 individuals were included in the analysis. After comparing two SEMs, we concluded that suprailiac and subscapular measures may indirectly affect hypertension susceptibility by influencing BMI. In conclusion, our analysis demonstrates that SEMs provide a better understanding of biological mechanisms by identifying greater numbers of genes and pathways.

• Journal of Conservation Science
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• v.34 no.1
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• pp.31-37
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• 2018

It was estimated that wooden warehouses excavated from Bongseon-ri site in Seocheon were built around the 5th century according to the soil layers and construction methods of earthen structures. In order to identify the exact date, three wooden materials (BSMG 01, 06, and 12) from wooden warehouses were analyzed through radiocarbon dating using wiggle match. The outermost ring of BSMG 01 produced a radiocarbon date (95.4% confidence interval) of AD 431~551, BSMG 06 produced a date of AD 460~570, and BSMG 12 produced dates of either AD 240~430 or AD 490~510. The common age of the three wooden materials was identified as AD 490-510 and coincided with the original estimated archaeological age. Therefore, this study proved the accuracy of radiocarbon dating using wiggle match.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.4
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• pp.8-16
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• 2009

An experimental study was carried out to investigate aerodynamic characteristics on reduced frequency of flapping wings. The half span of the wing is 28cm, and the mean chord length of wing is 10cm. In flight, the Reynolds Number range of birds is about $10^4$, and the reduced frequency during a level flight is 0.25. The experimental variables of present study were set to have similar conditions with the bird flight's one. The freestream velocities in a wind tunnel were 2.50, 3.75 and $5.00^m/s$, and the corresponding Reynolds numbers were $1.7{\times}10^4$, $2.5{\times}10^4$ and $3.3{\times}10^4$, respectively. The wing beat frequencies of an experimental model were 2, 3 and 4Hz, and the corresponding reduced frequency was decided between 0.1 and 0.5. Aerodynamic forces of an experimental flapping model were measured by using 2 axis load-cell. Inertial forces measured in a vacuum chamber were removed from measuring forces in the wind tunnel in order to acquire pure aerodynamic forces. Hall sensors and laser trigger were used to make sure the exact position of wings during the flapping motion. Results show that the ratio of downstroke in a wing beat cycle is increased as a wing beat frequency increases. The instantaneous lift coefficient is the maximum value at the end of downstroke of flapping wing model. It is found that a critical reduced frequency with large lift coefficient is existed near k=0.25.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.62-69
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• 2002

As Graphic Information is a intuitive, simple and definite media to transfer information to human, It is widely used and deserved as a information exchange and store media. But the graphic information is so abstract that a human may misunderstand that's real meaning. So In order to transfer a Exact information to a human, a additional picture and description is needed. So, in this paper, A authoring system is suggested that it can be able to give a additional information at each region in graphic information, and to structurize relations between each region and to give linking information between each region using XML Linking Notation. In this paper, An suggested authoring system is implemented to support a authoring facility which is to display graphical information of CGM(Computer Graphic Metafile) and BMP, and to define structural information by selecting each region of graphics image on screen directly, and to save that structural information and linking information with XML Linking notation, and to support a browsing facility which to find hot spot using a structurized graphic information and then to show a proper graph.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2107-2112
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• 2016

This paper is designed to develop a Gimbal control stabilizer for drones Gimbal system control for drone for 3D image to make sure clean image in the shaking and wavering environments of drone system. The stabilizer is made of tools which support camera modules and IMU(Inertial Measurement Unit) sensor modules follow exact angles, which can brock vibrations outside of the camera modules. It is difficult for the camera modules to get clean image, because of irregular movements and various vibrations produced by flying drones. Moreover, a general PID controller used for the movements of rolling, pitching and yawing in order to control the various vibrations of various frequencies needs often to readjust PID control parameters. Therefore, this paper aims to conduct the Intelligent-PID controller as well as design the Gimbal control stabilizer to get clean images and to improve irregular movements and various vibrations problems referenced above.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.556-565
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• 2009

Automated visual grading system of lumber needs correct input image. In order to create a correct image of domestic red pine lumber 3.6 m long feeding on a conveyer, part images were captured using area sensor and template matching algorithm was applied to merge part images. Two kinds of template matching algorithms and six kinds of template sizes were adopted in this operation. Feature extracted method appeared to have more excellent image merging performance than fixed template method. Error length was attributed to a decline of similarity related by difference of partial brightness on a part image, specific pattern and template size. The mismatch part was repetitively generated at the long grain. The best size of template for image merging was $100{\times}100$ pixels. In a further study, assignment of exact template size, preprocessing of image merging for reduction of brightness difference will be needed to improve image merging.

• Kyungpook Mathematical Journal
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• v.28 no.2
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• pp.185-196
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• 1988

We study existence of polynomial integrating factors and solutions F(x, y)=c of first order nonlinear differential equations. We characterize the homogeneous case, and give algorithms for finding existence of and a basis for polynomial solutions of linear difference and differential equations and rational solutions or linear differential equations with polynomial coefficients. We relate singularities to nature of the solution. Solution of differential equations in closed form to some degree might be called more an art than a science: The investigator can try a number of methods and for a number of classes of equations these methods always work. In particular integrating factors are tricky to find. An analogous but simpler situation exists for integrating inclosed form, where for instance there exists a criterion for when an exponential integral can be found in closed form. In this paper we make a beginning in several directions on these problems, for 2 variable ordinary differential equations. The case of exact differentials reduces immediately to quadrature. The next step is perhaps that of a polynomial integrating factor, our main study. Here we are able to provide necessary conditions based on related homogeneous equations which probably suffice to decide existence in most cases. As part of our investigations we provide complete algorithms for existence of and finding a basis for polynomial solutions of linear differential and difference equations with polynomial coefficients, also rational solutions for such differential equations. Our goal would be a method for decidability of whether any differential equation Mdx+Mdy=0 with polynomial M, N has algebraic solutions(or an undecidability proof). We reduce the question of all solutions algebraic to singularities but have not yet found a definite procedure to find their type. We begin with general results on the set of all polynomial solutions and integrating factors. Consider a differential equation Mdx+Ndy where M, N are nonreal polynomials in x, y with no common factor. When does there exist an integrating factor u which is (i) polynomial (ii) rational? In case (i) the solution F(x, y)=c will be a polynomial. We assume all functions here are complex analytic polynomial in some open set.

• Journal of Korea Water Resources Association
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• v.51 no.10
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• pp.895-903
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• 2018

There are a large number of weirs installed in rivers of Korea, and these characteristics are not common in other countries. When the flow passes through a structure such as a weir, discontinuous flow occurs. In terms of numerical simulation, it affects the numerical instability due to the balance between the flow term and the source term. In order to solve these problems, many researchers used empirical formulas or numerical scheme simplification. Recently, researches have been conducted to use more accurate numerical scheme. K-River was developed to reflect the characteristics of domestic rivers and calculate the discontinuous flow more accurately. For the verification of K-River, 1) numerical experiment simulations with a bump in the bed, 2) laboratory experiment of hydraulic jump simulation, 3) real river were performed. K-River verified its applicability by simulating results similar to the exact solution and observed value in all simulations.

• Korean Journal of Organic Agriculture
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• v.7 no.2
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• pp.125-151
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• 1999

After the release of facts that the high nitrate contents in vegetables by Korean organic farming, organic farmers were recommended by Korean Organic Farmer Association to apply 20t/ha compost while they applied before as much as they could, sometimes even more than 100t/ha. This study was aimed to check the safety of Korean organic product in terms of nitrate content. Current nitrate content in leaf and root vegetables by 3 different farming systems(organic farming, conventional farming, greenhouse farming) were monitored and furthermore it was compared with previously published another data in Korea to find out any changes among the monitored years(1993-1999). Current nitrate content in chinese cabbage, lettuce and kale became less compare to those of the beginning of monitoring, and especially those cultivated organic farming got the lowest value while previous organic vegetables at beginning of 90's showed the higher value than those cultivated in greenhouse. This decrease in organic vegetables was affected by less application rate of organic fertilizer than before at 20t/ha. But the nitrate level by organic farming was still higher compare to those cultivated by conventional farming in open field, since currently monitored organic vegetables were cultivated basically in greenhouse condition. It shows the organic farmer the necessity of transfer their farming site and condition from greenhouse to open field in order to decrease of its high level of nitrate caused long-term application and slow release characteristics of organic fertilizer. It was concluded the adoption of soil nitrate test to recommend a organic farmer the exact application rate for need of crop growth. Additionally the mechanism of lower nitrate accumulation in rice and fruit vegetables were also discussed in the paper.

• Journal of Fashion Business
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• v.12 no.3
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• pp.99-115
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• 2008

International exchange gets active in nations with the increase of Internet use and heading toward digital age. Thus the communication conveying image of nations effectively plays an important role in an international society. Sports events are regarded as important international exchange events and good opportunities for public relations of one's own country and taken as tools of planting good images in other nations. This study surveyed the concept and history of uniform through the documents and previous studies in order to find the aesthetic characteristics of sportswear uniform applying the image of national ensign and investigates the origin and start time in Korea of selected 6 sports items. As a result of finding the expression way of ensign image and drawing the aesthetic characteristics by analyzing the use and variation of ensign colors, the use of colors other than ensign and reflection of ensign form in collected 60 sports uniforms, this study could draw the symbolical beauty, beauty of variation and beauty of brevity. First, symbolical beauty is the aesthetic characteristics expressing uniforms by using the pattern ensign symbolizes and ensign colors themselves or enlarging a part of ensign. Second, beauty of variation is the aesthetic characteristics creating geometrical new patterns in uniform through the distortion and exaggeration of ensign shape, or transforming the colors themselves of ensign. Third, beauty of brevity is the aesthetic characteristics using other colors only as decorative factor while applying the main colors of ensign to the most part of uniform, or unifying the uniforms with only one color of ensign. As a result of survey, the proportion of the symbolical beauty was highest in summer season and beauty of brevity and beauty of variation followed and the proportion of beauty of variation was highest and the symbolical beauty and beauty of brevity followed after that in winter season. This study found the way of expressing image of one's own country in sports uniform through this article, expecting the exact recognition on sports uniform and the diversity of sports uniform design in which the images of the nation are expressed more variously.