• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.507-514
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• 2023

The purpose of this study is to find a formula that can easily calculate the effective photon energy in the X-ray beam of mammography. The tube voltage measured for each set tube voltage was obtained using the X2 MAM Sensor. The mass attenuation coefficient for aluminum of the aluminum filter was obtained from the half value layer measurement from each measured tube voltage X-ray beam. The mass attenuation coefficient of aluminum obtained from each measured tube voltage X-ray beam was corresponded to the mass attenuation coefficient of aluminum for each photon energy obtained from NIST. The photon energy corresponding to the matching mass attenuation coefficient was determined as the effective photon energy. The formula for calculating the determined effective photon energy was obtained by polynomial matching of the effective photon energy for each tube voltage in the Origin pro 2019b statistical program as y = 28.98968-1.91738x + 0.07786x2-0.000946717x3. Here, x is the measuring tube voltage and y is the effective photon energy. The calculation formula of the effective photon energy of the mammography X-ray beam obtained in this study is considered to be very useful in obtaining the interaction coefficient between the X-ray beam and a certain substance in clinical practice.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.42-42
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• 2010

We have characterized the previously undescribed parameters for engineering the electrical properties of single-walled carbon nanotube (SWCNT) films for technological applications. The surface tension of the top coating passivation material and matching coefficients of thermal expansion for the substrate and carbon nanotube network are two crucial parameters for the fabrication of reliable and highly conductive single-walled carbon nanotube network thin films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.278-278
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• 2010

We have characterized the previously undescribed parameters for engineering the electrical properties of single-walled carbon nanotube (SWCNT) films for technological applications. The surface tension of the top coating passivation material and matching coefficients of thermal expansion for the substrate and carbon nanotube network are two crucial parameters for the fabrication of reliable and highly conductive single-walled carbon nanotube network thin films.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.506-509
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• 2008

Mathematical models have been developed to calculate hydrodynamic characteristics of perforated-wall structures. Most of the models separate the fluid regions into front and back of the wall, assume the solution in each region, and calculate the solution by using the matching condition at the wall. The matching condition involves the permeability parameter, which can be calculated by the methods proposed by Mei et al. or Sollitt and Cross. In this study, we compare these two methods. The former is advantageous because all the related variables are known, but it gives wrong result in the limit of long waves, i.e. zero transmission and perfect reflection of very long waves. In deep water, the latter predicts smaller transmission and larger reflection than the former, and vice versa in shallow water. In the latter method, the friction coefficient decreases as the wall thickness or the porosity of the wall increases.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.430-432
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• 2010

We verified through a noncritical phase-matched second-harmonic generation experiment that the periodically-poled $LiNbO_3$ (PPLN) had a large effective nonlinear optical coefficient, demonstrating that the QPM grating was uniform throughout the entire length of PPLN. The quasi-phase matching temperature was $193.4^{\circ}C$. The maximum SHG output power at the fundamental power of 2.0 W was found to be 18.0 mW; generated second-harmonic beam was found to have no photorefractive effect.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4D
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• pp.687-693
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• 2006

Image co-registration is the process of overlaying two images of the same scene, one of which represents a reference image, while the other is geometrically transformed to the one. In order to improve efficiency and effectiveness of the co-registration approach, the author proposed a pre-qualified area matching algorithm which is composed of feature extraction with canny operator and area matching algorithm with cross correlation coefficient. For refining matching points, outlier detection using studentized residual was used and iteratively removes outliers at the level of three standard deviation. Throughout the pre-qualification and the refining processes, the computation time was significantly improved and the registration accuracy is enhanced. A prototype of the proposed algorithm was implemented and the performance test of 3 Landsat images of Korea. showed: (1) average RMSE error of the approach was 0.435 pixel; (2) the average number of matching points was over 25,573; (3) the average processing time was 4.2 min per image with a regular workstation equipped with a 3 GHz Intel Pentium 4 CPU and 1 Gbytes Ram. The proposed approach achieved robustness, full automation, and time efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.105-108
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• 2003

In the framework of universal multimedia access, one challenge for video transmission (communication) is to deliver video content through heterogeneous network channels matching the diversity of client devices. As one of the many adaptation methods, media transcoding is commonly considered. Particularly, FD (Frame Dropping)/CD Coefficient Dropping) transcoding is used due to the low computational complexity and simple implementation. In this scheme, CD is simply implemented by truncating the high frequency AC DCT coefficient bits. But, the CD error tends to be propagated within single GOV. In this paper, we derive the distortion relationships between CD error and propagation error, and investigate the error characteristics by computer simulations. The CD error characteristics can be effectively used in the FD/CD transcoding scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.661-668
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• 2012

A coaxial-cable impedance transformer that can be used in high power and wideband frequency range is an arbitrary impedance transformation ratio by an additional coaxial cable. The coaxial-cable impedance transformer to be 50-${\Omega}$ to 25-${\Omega}$ impedance transformation ratio is easily operated an wideband power divider by connecting two 50-${\Omega}$ lines at 25-${\Omega}$ impedance point. This wideband power divider has a poor output matching characteristic and a poor isolation characteristic between two output ports. In this paper, it proposes a coaxial-cable power divider to be a good output matching and isolation characteristics as it uses the singly terminated filter design theory. The odd-mode operation characteristic of the suggested power divider to use singly terminated low pass filter coefficient due to matching order and ripple value is examined by ADS program. And, it fabricates and measures the operation characteristic of 2-way power divider with 2nd-order and 4th-order matching circuit.

• Journal of Korea Multimedia Society
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• v.16 no.12
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• pp.1376-1384
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• 2013

In this paper, we propose an automaticdetection method of foreign bodies through template matching in industrial CT volume data. Our method is composed of three main steps. First,Indown-sampling data, the product region is separated from background after noise reduction and initial foreign-body candidates are extracted using mean and standard deviation of the product region. Then foreign-body candidates are extracted using K-means clustering. Second, the foreign body with different intensity of product region is detected using template matching. At this time, the template matching is performed by evaluating SSD orjoint entropy according to the size of detected foreign-body candidates. Third, to improve thedetection rate of foreign body in original volume data, final foreign bodiesare detected using percolation method. For the performance evaluation of our method, industrial CT volume data and simulation data are used. Then visual inspection and accuracy assessment are performed and processing time is measured. For accuracy assessment, density-based detection method is used as comparative method and Dice's coefficient is measured.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.79-84
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• 2019

This paper compare the performance of CM-MMA (Constellation Matching-MMA) and RMMA (Region-based MMA) blind equalization algorithm for improve the QoS by minimizing the intersymbol interference that is occurred in nonlinear communication channel when transmitting the QAM signal. In the tap coefficient update for adaptive, CM-MMA use the error of nonconstant modulus signal adding the current MMA cost fuction and constellation matching error terms of sinusoidal power function, and the RMMA use the error by transfoms the nonconstant modulus signal of equalizer output constellation to 4-QAM constant modulus signal. They has different equalization performance by these error signal, it were compared in this paper by simulation, and performance index such as output signal constellation of equalizer, residual isi, maximum distortion, SER curves are applied for this. As a result of computer simulation, the RMMA has more better performance in the every performance index, convergence speed, residual value, noise robustness compared to CM-MMA.