• Polymer(Korea)
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• v.27 no.4
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• pp.313-322
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• 2003

The morphology of poly(ethylene terephthalate) (PET)/poly(m-xylene adipamide) (MXD-6) blends, which was prepared by adding compatibilizer and interchange reaction agent, was investigated. The morphological change in the stretched blend films was also studied. The stretched film showed a dispersed MXD-6 fibril. This fibril became finer with increasing draw ratio (DR). The addition of compatibilizer and interchange reaction agent had no effect on the improvement of interfacial adhesion but caused a defect between the continuous phase and the dispersed phase, leading to the formation of irregular fibril. The change in the superstructure of blends with composition and draw ratio was examined with light scattering (LS). The H$\sub$v/ LS patterns showed a double-cross type pattern consisting of a broad rod-like pattern and a sharp cross streak. On the basis of the model calculation of the H$\sub$v/ pattern, it was found that the appearance of the double-cross type pattern was attributed to the stacking of crystals oriented along the draw direction. The crystals were gradually oriented to the stretching direction with draw ratio. As a result, the high level of orientation was obtained fur the sample of draw ratio is 6.0.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.99-108
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• 2008

For video compression, we have to consider two performance factors that are the search speed and coded video's quality. In this paper, we propose an enhanced fast block matching algorithm using the spatial correlation of the video sequence and the center-biased characteristic of motion vectors(MV). The proposed algorithm first finds a predicted motion vector from the adjacent macro blocks of the current frame and determines an exact motion vector using the cross pattern and a flat hexagon search pattern. From the performance evaluations, we can see that our algorithm outperforms both the hexagon-based search(HEXBS) and the cross-hexagon search(CHS) algorithms in terms of the search speed and coded video's quality. Using our algorithm, we can improve the search speed by up to 31%, and also increase the PSNR(Peak Signal Noise Ratio) by at most 0.5 dB, thereby improving the video quality.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.95-98
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• 1989

A new associative memory model using the SDF filter, one of the multiple filter for pattern recognition, is suggested in this paper. The SDF filter characteristics such as pattern classification lets the memorized patterns have orthogonal characteristics one another, so that enhances the associative memory's retrieval ability to the original pattern. The computer simulation shows that this new model is very useful in case that the imput patterns are seriously distorted and the cross-correlation between the memorized patterns is very high.

• Wind and Structures
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• v.30 no.5
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• pp.525-532
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• 2020

This work numerically investigates the effects of Reynolds number Re_D (= 100 - 150), cross-sectional aspect ratio AR = ( 0.25 -1.0), and attack angle α (= 0° - 90°) on the forces, Strouhal number, and wake of an elliptical cylinder, where Re_D is based on the freestream velocity and cylinder cross-section height normal to the freestream flow, AR is the ratio of the minor axis to the major axis of the elliptical cylinder, and α is the angle between the cylinder major axis and the incoming flow. At Re_D = 100, two distinct wake structures are identified, namely 'Steady wake' (pattern I) and 'Karman wake followed by a steady wake (pattern II)' when AR and α are varied in the ranges specified. When Re_D is increased to 150, an additional wake pattern, 'Karman wake followed by secondary wake (pattern III)' materializes. Pattern I is characterized by two steady bubbles forming behind the cylinder. Pattern II features Karman vortex street immediately behind the cylinder, with the vortex street transmuting to two steady shear layers downstream. Inflection angle α_i = 32°, 37.5° and 45° are identified for AR = 0.25, 0.5 and 0.75, respectively, where the wake asymmetry is the greatest. The α_i effectively distinguishes the dependence on α and AR of force and vortex shedding frequency at either Re_D. In Pattern III, the Karman street forming behind the cylinder is modified to a secondary vortex street. At a given AR and α, Re_D = 150 renders higher fluctuating lift and Strouhal number than Re_D = 100.

• Fashion & Textile Research Journal
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• v.17 no.3
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• pp.447-461
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• 2015

The purpose of this study is to develop a torso pattern that is highly representative for the proper body shape of women in their thirties. Size data of the women with age of 30 through 39 from the database of Size Korea 2004 were used for the study. In order to develop a master pattern which will be used as the benchmark for grading of research group, 4 existing torso block drafting methods were compared based on the data gathered and the block with the highest evaluation score was utilized as a reference point. For the analysis, data was divided into four types, only the data of 138 subjects which were evaluated at least by four or more experts as valid were used for the study. The major results can be summarized as follow. The women of bust girth of 91cm and height of 160cm which was turned out to be representative type of research group were used as standard measurement for the purpose of reflecting not only curve length of the 3D analysis measurement but also the difference between front and back thickness to the pattern. Dart locations were set based on front and back torso ease, shoulder area revisions, front sagging length 1.5cm and cross section crevice length analysis. According to the experts' appearance evaluation of the pattern was found to be better than the control pattern which was regarded as the best among 4 patterns created based on existing torso block drafting methods.

• Journal of Advanced Navigation Technology
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• v.16 no.3
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• pp.426-432
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• 2012

In this paper, we investigate the signal to noise ratio (SNR) estimation performance of Cross quadrature amplitude modulation (QAM), which is being used for asymmetric digital subscriber line (ADSL), very high bit rate digital subscriber line (VDSL), and digital video broadcasting - cable (DVB-C), and has been found to be useful in adaptive modulation and blind equalization. At first, the symbol error rate (SER) performance of Cross QAM is analyzed in Rayleigh fading channel. Then we suggest error vector magnitude (EVM) based SNR estimation utilizing the selected constellation points having different types of decision region from one another, and verify that SNR estimation performance of each points have different performance pattern through simulation. From the simulation results, it has been found that when suggested selected constellation points are used for SNR estimation in Cross QAM, estimation performance is enhanced in additive white Gaussian noise (AWGN) channel or Ricean fading channel.

• Journal of Family Resource Management and Policy Review
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• v.2 no.1
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• pp.1-14
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• 1998

The purpose of this study was to examine patterns ofmoney management and control of family finances. The data for this study were collected from 311 wives who were currently employed in professional, managerial, and clerical occupation living or employed in Seoul. Frequency, percentage and cross-tab analysis were used to analyze the data. The results were as follows: 1) money management patterns were classified into six types; wife-management pattern, wife-management/husband-alienation pattern, wife-management/husband-involvement patter, joint management pattern, joint/separate mixed pattern, and multi management pattern. Among them wife-mannagement pattern was used most frequencly by the couples. 2) Four family finance control patterns were found and named by joint control, wife control, husband control, and self control. The joint control pattern was found to be the most prevalent one. 3) Money management patterns influenced how family finances were controled.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.233-240
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• 2007

In this paper, the broadband cross monopole antenna is presented and the radiation characteristics are investigated. The presented broadband cross monopole antenna is composed of the cross monopole element and the folded short stub, which has a excellent band characteristics more than the existing cross monopole antenna. To conform the broadband characteristics of the presented antenna, the experimental antenna is designed, fabricated, and its radiation characteristics are measured in $1.75\sim2.655\;GHz$. It is shown that the designed antenna has the nondirectional pattern in the horizontal plane, the directional pattern in the vertical plane, VSWR less than 1.5, and gain in $2.17\sim4.87\;dBi$. From these results, the presented antenna is conformed as a broadband indoor antenna which can be used for PCS, WCDMA, Wibro, and satellite DMB band.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.165-166
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• 2006

Surface pattern of tribological applications is an attractive technology of engineered surface. Therefore, friction reduction is considered to be necessary for improved efficiency of machines. This study investigated the effect of friction property fur angles of micro-scale crosshatch grooved surface pattern on bearing steel flat mated with pin-on-disk. We obtain sample which can be fabricated by photolithography process. We discuss friction property depend on an angle of cross-hatch grooved pattern. We can verify the lubrication mechanism as a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter under the lubrication condition. It was found that the friction coefficient was related to angle of crosshatch on surface, even when surface pattern was the same density.

• Wind and Structures
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• v.26 no.5
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• pp.267-277
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• 2018

Numerical simulations are performed of a long flexible cylinder undergoing vortex-induced vibration at a Reynolds number of 500. The cylinder is pinned at both ends, having an aspect ratio of 100 (cylinder length to cylinder diameter) and a mass ratio of 4.2 (structural mass to displaced fluid mass). Temporal and spatial information on the cross-flow (CF) and in-line (IL) vibrations is extracted. High modal vibrations up to the $6^{th}$ in the CF direction and the $11^{th}$ in the IL direction are observed. Both the CF and IL vibrations feature a multi-mode mixed pattern. Mode competition is observed. The $2^{nd}$ mode with a low frequency dominates the IL vibration and its existence is attributed to a wave group propagating back and forth along the span. Distributions of fluid force coefficients are correlated to those of the CF and IL vibrations along the span. Histograms of the x'-y motion phase difference are evaluated from the total simulation time and a complete vibration cycle representing the standing or travelling wave pattern. Correlations between the phase difference and the vibrations are discussed. Vortex structures behind the cylinder show an interwoven near-wake pattern when the standing wave pattern dominates, but an oblique near-wake pattern when the travelling wave pattern prevails.