• Journal of Korea Society of Industrial Information Systems
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• v.24 no.1
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• pp.1-12
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• 2019

This paper proposes a new motion vector smoothing and motion compensation method to increase the frame rate of videos. The proposed method reduces false motion vector smoothing by improving the weight with reflecting accuracy to overcome the limitation of the conventional motion vector smoothing using the adaptively weighted vector median. Also, to improve the interpolated image quality of the conventional OBMC(Overlapped Block Motion Compensation), a scheme that divides an original block into 4 sub-blocks and then generates the interpolated frame using the reestimated motion vector for each sub-block is proposed. The simulation results prove that the proposed method can provide much better objective and subjective image quality than the conventional method.

• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.28-35
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• 2021

In this study, an image processing method for the measurement of two-phase bubbly flow is developed. Shadowgraphy images obtained by high-speed camera are used for analysis. Some bubbles are generated as single unit and others are overlapped or clustered. Single bubbles can be easily analyzed using parameters such as bubble shape, centroid, and area. But overlapped bubbles are difficult to transform clustered bubbles into segmented bubbles. Several approaches were proposed for the bubble segmentation such as Hough transform, connection point method and watershed. These methods are not enough for bubble segmentation. In order to obtain the size distribution of bubbles, we present a method of splitting overlapping bubbles using watershed and approximating them to ellipse. There is only 5% error difference between manual and automatic analysis. Furthermore, the error can be reduced down to 1.2% when a correction factor is used. The ellipse fitting algorithm developed in this study can be used to measure bubble parameters accurately by reflecting the shape of the bubbles.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.172-177
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• 2022

In general, detection robots using ultrasonic sensors are equipped with sensors to protrude outward or to contact objects. However, in the case of a screw-propelled robot that detects the inside of a reactor tendon duct, if the ultrasonic sensor protrudes to the outside, resistance due to grease is generated, and thus the propulsion efficiency is reduced. In order to increase the propulsion efficiency, the screw must be sharp, and the sharper the screw, the more difficult it is to apply a high-performance ultrasonic sensor, and the detection efficiency decreases. This paper proposes a screw shape-changing mechanism that can improve both propulsion efficiency and detection efficiency. This mechanism includes an overlapped helical ring (OHR) structure and a magnetic clutch system (MCS), and thus the shape of a screw may be changed to a compact size. As a result, the Screw-propelled robot with this mechanism can reduce the overall length by about 150 mm and change the shape of the screw faster and more accurately than a robot with a linear actuator.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.6
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• pp.6-15
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• 2009

In this paper, a new 4-way search window is designed for the high-performance 2D PE architecture in H.264 Motion Estimation(ME) to improve the memory bandwidth. While existing 2D PE architectures reuse the overlapped data of adjacent search windows scanned in 1 or 3-way, the new window utilizes the overlapped data of adjacent search windows as well as adjacent multiple scanning (window) paths to enhance the reusage of retrieved search window data. In order to scan adjacent windows and multiple paths instead of single raster and zigzag scanning of adjacent windows, bidirectional row and column window scanning results in the 4-way(up. down, left, right) search window. The proposed 4-way search window could improve the reuse of overlapped window data to reduce the redundancy access factor by 3.1, though the 1/3-way search window redundantly requires $7.7{\sim}11$ times of data retrieval. Thus, the new 4-way search window scheme enhances the memory bandwidth by $70{\sim}58%$ compared with 1/3-way search window. The 2D PE architecture in H.264 ME for 4-way search window consists of $16{\times}16$ pe array. computing the absolute difference between current and reference frames, and $5{\times}16$ reusage array, storing the overlapped data of adjacent search windows and multiple scanning paths. The reference data could be loaded upward and downward into the new 2D PE depending on scanning direction, and the reusage array is combined with the pe array rotating left as well as right to utilize the overlapped data of adjacent multiple scan paths. In experiments, the new implementation of 4-way search window on Magnachip 0.18um could deal with the HD($1280{\times}720$) video of 1 reference frame, $48{\times}48$ search area and $16{\times}16$ macroblock by 30fps at 149.25MHz.

• Korean Journal of Cognitive Science
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• v.2 no.2
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• pp.261-278
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• 1990

Two experiments were performed to test whether the perception of subjective contours occurs not only through bottom-up processes but also throught top-down processes by manipilating such cognitive factors as superimposition cues and selective attention.In the first experiment,the phenomenon of neon color spreading effect was used to investigate the effect of superimpoed Kanizsa triangles.To identify the effect of superimposition, two different colors were used,one for each overlapped Kanizsa triangle,and the subjects were asked which neon-like color they saw for the overlapped portion.Result indicates that the only neon-like color of the superimposing triangle can be perceived,which implies that super impostition cues may act upon the formation process of subjective contour as a a sort of top-down information.In the second experiment,two partially ovwelapped Kanizsa squares of which direction of superimposition were ambiguous and thus reversable depending on the observer's mental set were used to inverstigate the effect of selective attention.Subjects were instructed to pay attention only to one of the squares and report the neon- like color of the overlapped portion of them.Result shows that the subjects perceive only the neon-like color of superimposing square,which implies that such cognitive factors as selective attention may strongly influence the formation of subjective contours. In conclusion,the results of this study show that the subective contour does not depend only on bottom-up processes but also on such cognitive factors as super-imposition cues and selective attention.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.7-16
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• 2015

The transmitter of quadrature multiplexed GMSK (QM-GMSK) is composed of two quadrature multiplexed GMSK modulators. QM-GMSK has a slightly increased spectrum main lobe compared with $Q^2PSK$ or QMSK, but it has highly suppressed side lobes. As a result, practical spectrum efficiency of QM-GMSK is achieved. By replacing the baseband elementary pulses of QM-GMSK with their approximate, the squared sinusoid of half-period, offset-$Q^2PSK$($OQ^2PSK$) is obtained. The $OQ^2PSK$ signal has similar spectral properties to QM-GMSK. The transmitter of $OQ^2PSK$ can be simply implemented without the Gaussian lowpass filter, which is required in QM-GMSK transmitter. In this paper, we propose an overlapped pulse shaping in $OQ^2PSK$ with RC(raised-cosine) or SRC(squared raised-cosine) pulses of length longer than the symbol period. Power spectrum of the proposed modulation scheme exhibits further suppressed side lobes, hence enhanced spectrum efficiency is obtained. Simulation results indicate that BER performance of the proposed scheme is comparable to that of $OQ^2PSK$.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.501-509
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• 2015

Purpose: To evaluate the reliability of refractive power by comparing the marked refractive power in an automatic phoropter and actually measured spherical/cylindrical refractive power. Methods: Actual refractive power of minus spherical lens and cylindrical lens in an automatic phoropter was measured by a manual lensmeter and compared with the accuracy of marked refractive power. Furthermore, combined refractive power and spherical equivalent refractive power of two overlapped lenses were compared and evaluated with the refractive power of trial lens. Results: An error of 0.125 D and more against the marked degree was observed in 70.6% of spherical refractive power of spherical lens which is built in phoropter, and the higher error was shown with increasing refractive power. Single cylindrical refractive power of cylindrical lens is almost equivalent to the marked degree. Combined spherical refractive power was equivalent to spherical refractive power of single lens when spherical lens and cylindrical lens were overlapped in a phoropter. Thus, there was no change in spherical refractive power by lens overlapping. However, there was a great difference, which suggest the effect induced by overlapping between cylindrical refractive power and the marked degree when spherical lens and cylindrical lens were overlapped. Spherical equivalent refractive power measured by using a phoropter was lower than that estimated by trial glasses frame and marked degree. The difference was bigger with higher refractive power. Conclusions: When assessment of visual acuity is made by using an automatic phoropter for high myopes or myopic astigmatism, some difference against the marked degree may be produced and they may be overcorrected which suggests that improvement is required.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.876-884
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• 2017

The current-voltage characteristics of Silicon(Si), Germanum(Ge), and hetero tunnel field-effect transistors(TFETs) with source-overlapped gate structure was investigated using TCAD simulations in terms of tunneling. A Si-TFET with gate oxide material $SiO_2$ showed the hump effects in which line and point tunneling appear simultaneously, but one with gate oxide material $HfO_2$ showed only the line tunneling due to decreasing threshold voltage and it shows better performance than one with gate oxide material $SiO_2$. Tunneling mechanism of Ge and hetero-TFETs with gate oxide material of both $SiO_2$ and $HfO_2$ are dominated by point tunneling, and showed higher leakage currents, and Si-TFET shows better performance than Ge and hetero-TFETs in terms of SS. These simulation results of Si, Ge, and hetero-TFETs with source-overlapped gate structure can give the guideline for optimal TFET structures with non-silicon channel materials.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.47-53
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• 2018

This paper proposes a method to express an MP3 audio file by a series of color QR codes which can be printed on the paper. Moreover, the method can compress the data considerably. Firstly, an MP3 file is divided into many small files which have maximum capacity of binary file of a QR code. Secondly, the multiple files are converted to multiple black-and-white QR codes. Lastly, every three QR codes are combined into color QR codes. When combining, each of three black-and-white QR codes are regarded as red, green, blue components respectively. In this method, the areas of a color QR code where two QR codes are overlapped are expressed by the colors Cyan, Magenta and Yellow. And the areas where three components are overlapped are expressed by white color. Contrarily, the areas that no components are overlapped are expressed by white color. Experimentation result shows that an MP3 file with 8.5MB the original MP3 files are compressed with the compression rate around 15.7. This method has the advantage that can be used in the environments that the internet access is impossible.

• Korean Security Journal
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• no.61
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• pp.377-400
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• 2019

Photography is the most commonly used method of documenting the crime and incident scene as it helps maintaining chain of custody (COC) and prove integrity of the physical evidence. It can also capture phenomena as they are. However, digital images can be manipulated and lose their authenticity as admissible evidence. Thus only limited techniques can be used to enhance images, and one of them is Fourier transform. Fourier transform refers to transformation of images into frequency signals. Fast Fourier transform (FFT) is used in this study. In this experiment, we overlapped fingerprints with graph paper or other fingerprints and separated the fingerprints. Then we evaluated and compared quality of the separated fingerprints to the original fingerprints, and examined whether the two fingerprints can be identified as same fingerprints. In the case of the fingerprints on graph paper and general pattern-overlapping fingerprints, fingerprint ridges are enhanced. On the other hand, in case of separating complicated fingerprints such as core-to-core overlapping and delta-to-delta overlapping fingerprints, quality of fingerprints can be deteriorated. Quality of fingerprints is known to possibly bring negative effects on the credibility of examiners. The result of this study may be applicable to other areas using digital imaging enhancement technology.