• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.74-78
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• 2014

This paper presents a modified TEM horn that improves radiation characteristics at a low frequency region. The proposed antenna consists of an asymmetric TEM (ATEM) horn and a loop structure with an elliptical shape. The bandwidth and gain at low frequency region can be enhanced by using the ATEM horn configuration and adding a loop structure with an elliptical shape to the ATEM horn. The bandwidth of the proposed antenna is from 2.14 to over 20 GHz, whereas that of the conventional TEM horn is from 2.7 to over 20 GHz, where the dimensions of both antennas are the same except for the thickness of the loop structure. The physical and electrical dimensions of the proposed antenna are $60mm{\times}62.5mm{\times}64mm$ ($width{\times}height{\times}length$) and $0.428{\lambda}_L{\times}0.445{\lambda}_L{\times}0.456{\lambda}_L$, where ${\lambda}_L$ corresponds to the lowest frequency of the bandwidth. The realized gain of the proposed antenna is improved by 0.802 dB on average at the low frequency region (2 to 8 GHz), where the maximum gain increase is 2.932 dB when compared to a conventional TEM horn.

• Journal of Digital Convergence
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• v.15 no.10
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• pp.357-366
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• 2017

The purpose of this study was identify the factors affecting serum vitamin D deficiency in korean women. This study used the data from the 5th Korea National Health and Nutrition Examinations Survey and analyzed the demographic characteristics, health related factors and serum vitamin D in women aged 19 and over. Data were analyzed using the IBM SPSS 18.0 program. As a result, vitamin D deficiency rate in Korean women was 81.4%. There were significant differences according to age, marital status, region, type of residence, family income, education level. The risk factors of vitamin D deficiency were age, marital status, region, without walking. According to the results of this study, further studies on the vitamin D deficiency factors by age group should be conducted and the stress relieve and physical activity of women should be promoted to prevent vitamin D deficiency.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1506-1508
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• 2015

A 2D barcode region localization system for the automatic inspection of a long distance logistics objects has been developed. For the successful 2D barcode localization, variance and frequency of the pixel distribution within average 2D barcodes is modeled and the average model of 2D barcode is combined with the corner features detection to localize the final 2D barcode candidates. An automatic 2D barcode localization software was developed with the multiple features mixture method and we tested our system on real camera images of several popular 2D barcode symbologies.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.154-159
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• 1994

The magneto-optical Kerr spectra(${\lambda}=250~700nm$) of amorphous RE-Co(RE=Ce, Nd, Pr, Gd, Tb, Er, Ho) are compared with those of Y-Co films. It has been found that the Kerr rotation of RE-Co is mainly due to Co in the long wavelength region, whereas at short wavelength Ce, Pr, Nd, and Gd contribute positively, and Tb, Ho, and Er contribute negatively to the Kerr rotation of RE-Co amorphous films. In the interesting energy region(1.5~5.0 eV), the magneto-optical contribution of Pr and Nd are thought to be related with $4f{\uparrow}->5d{\uparrow}$ interband transition, and the contribution of Ce and Gd might be concerned with d->p interband transition. The magneto-optical effect of Tb in the short wavelength region might be related with $4f{\downarrow}->5d{\downarrow}$ and/or $5d{\downarrow}->4f{\downarrow}$, and that of Ho and Er can be explained by $4f{\downarrow}->5d{\downarrow}$ magneto-optical interband transition.

• Journal of computational fluids engineering
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• v.18 no.4
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• pp.47-52
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• 2013

In the present study, the turbulent flow from an annular jet is investigated by using large eddy simulation. Particularly, the effect of the ratio of the inner and outer diameters is one of the main interests of this study. The instantaneous fields presented in this paper showed that behind the jet exit the backflow region, as well known in literatures, exists, and its detailed behavior depends on the ratio of the inner and outer diameters ($D_1/D_2$). The dependence on $D_1/D_2$ is attributed to the different shear layer development according to $D_1/D_2$. At small $D_1/D_2$, the development of the outer shear layer is similar to that from the circular jet. However, with increasing $D_1/D_2$, the interaction between the outer and inner shear layers becomes strong, resulting in fast transition to turbulence.

• Journal of Biosystems Engineering
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• v.27 no.3
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• pp.227-234
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• 2002

This study was conducted to nondestructively estimate the volumetric information of peach and pit and to visualize the 3D information of internal structure from magnetic resonance imaging(MRI) data. Bruker Biospec 7T spectrometer operating at a proton reosonant frequency of 300 MHz was used for acquisition of MRI data of peach. Image processing algorithms and visualization techniques were implemented by using MATLAB (Mathworks) and Visualization Toolkit(Kitware), respectively. Thresholding algorithm and Kohonen's self organizing map(SOM) were applied to MRI data fur region segmentation. Volumetric information were estimated from segemented images and compared to the actual measurements. The average prediction errors of peach and pit volumes were 4.5%, 26.1%, respectively for the thresholding algorithm. and were 2.1%, 19.9%. respectively for the SOM. Although we couldn't get the statistically meaningful results with the limited number of samples, the average prediction errors were lower when the region segmentation was done by SOM rather than thresholding. The 3D visualization techniques such as isosurface construction and volume rendering were successfully implemented, by which we could nondestructively obtain the useful information of internal structures of peach.

• Current Optics and Photonics
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• v.1 no.3
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• pp.239-246
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• 2017

A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

• Korean Journal of Computational Design and Engineering
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• v.7 no.2
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• pp.75-80
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• 2002

This paper details a robust and efficient algorithm for point classification with respect to a polygon in 2D real number domain. The concept of tolerance makes this algorithm robust and consistent. It enables to define‘on-boundary’ , which can be interpreted as either‘in-’or‘out-’side region, and to manage rounding errors in floating point computation. Also the tolerance is used as a measure of reliability of point classifications. The proposed algorithm is based on a ray-intersection technique known as the most efficient, in which intersections between a ray originating from a given test point and the boundary of a region are counted. An odd number of intersections indicates that the point is inside region. For practical examples the algorithm is most efficient because most edges of the polygon region are processed by simple bit operations.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.333-342
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• 2001

To detect the genetic variations among infectious bursal disease (IBD) vaccine strains, the hypervariable region of VP2 gene of seven IBDV vaccine strains were amplified using reverse transcriptase/polymerase chain reation(RT/PCR). Ampllified PCR products of IBDV were cloned, sequenced, and compared with published sequences for IBDV. Vaccine strains (JOONG, HAN, B7, IB, BU2, G2, CIL) used in Korea and Korean field isolates (SH/92, K1, 310) had 81%(310 and HAN) ~ 98%(SH/92 and CIL) amino acid sequence similarity. Vaccine strains had 80%(HAN and IB) ~ 99%(JOONG and BU2) amino acid sequence similartiy. Intermediate plus vaccine strain, CIL was not substituted at positions 279(D $\rightarrow$ N) and 284(A $\rightarrow$ T), and conserved in serine-rich heptapeptide. At the two hydrophilic region, JOONG, IB and Bu2 strains had identical amino acid sequence comparing with STC strain. By phylogenetic analysis, JOONG and DAE strains were categorized in same group with BU2. The CIL and STC strains closely related but seperated from G2, HAN, B7 and IB strains.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.867-871
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• 2012

In this paper, we proposed and demonstrated a low loss $1{\times}4$ type plastic optical fiber(POF) coupler incorporating a polymer tapering waveguide region. To avoid leakage loss at the interfaces between the POF and the polymer waveguide, we employed two POF transition regions, in which the cross section of the POF is adiabatically converted from a circular to a rectangular shape without change of its cross-section area. The device was fabricated based on a injection mold made of a silicon rubber. The fabricated POF coupler showed 1.33 dB of excess loss and 2.2 dB of flatness.