• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.149-156
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• 1995

This paper suggests a new experimental system and protocol of mechanical analysis for arterial cross-section research. So far, most methods of arterial studies have been focused on the deformation measurement in longitudinal and circumferential direction. The deformation in radial direction has been theoretically assumed by Poisson's ratio and/or the incompressibility of arterial wall. Also, the radial gradient of strains are neglected. In fact, the radial deformation and radial gradient of strains against blood pressure are important to be observed in the pathological point of view of artery. Proposed experimental system and protocol are to measure the deformation of cross-sectional artery. Also, this method enables to measure the deformation of anterior, posterior, and side site of cross-sectional area. It is meaningful to correlate the mechanically experimented data with pathological data of athroscIerotic artery.

• Journal of the Korea Computer Industry Society
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• v.4 no.12
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• pp.953-964
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• 2003

In the block matching algorithm, search patterns of different shapes or sizes and the distribution of motion vectors have a large impact on both the searching speed and the image quality. In this paper, we propose a new fast block matching algorithm using the cross pattern and the flat-hexagon search pattern. Our algorithm first finds the motion vectors that are close to the center of search window using the cross pattern, and then lastly finds the other motion vectors that are not close to the center of search window using the flat-hexagon search pattern. Through experiments, compared with the hexagon-based search algorithm(HEXBS), the proposed cross pattern and flat-hexagonal pattern search algorithm(CFHPS ) improves about 0.2-6.2% in terms of average number of search point per motion vector estimation and improves about 0.02-0.31dB in terms of PSNR(Peak Signal to Noise Ratio).

• Journal of the Korean Geophysical Society
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• v.1 no.1
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• pp.51-58
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• 1998

A numerical program has been developed to model 2-D resistivity responses for a pole-pole array configuration in cross-hole resistivity measurements. Apparent resistivity and secondary potential were computed using the program for a cylindrical inhomogeneity in an uniform host medium excited by a point source of current in a borehole. Surprisingly apparent resistivity in the receiver hole turns out to be lower than the one of surrounding medium regardless of the conductivity of cylindrical inhomogeneity. Using only cross-hole data, therefore, it is impossible to interpret the conductivity of inhomogeneity. To overcome this problem, 3-D measurement and interpretation are necessary. If 3-D data acquisition is impossible, inline data should be used to get the information about the conductivity of inhomogeneity.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3597-3601
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• 2013

The reactions of bis(Y-aryl) chlorothiophosphates (1) with substituted anilines and deuterated anilines are investigated kinetically in acetonitrile at $55.0^{\circ}C$. The Hammett plots for substituent Y variations in the substrates show biphasic concave upwards with a break point at Y = H. The cross-interaction constants (${\rho}_{XY}$) are positive for both electron-donating and electron-withdrawing Y substituents. The kinetic results of 1 are compared with those of Y-aryl phenyl chlorothiophosphates (2). The cross-interaction between Y and Y, due to additional substituent Y, is significant enough to result in the change of the sign of ${\rho}_{XY}$ from negative with 2 to positive with 1. The effect of the cross-interaction between Y and Y on the rate changes from negative role with electron-donating Y substituents to positive role with electron-withdrawing Y substituents, resulting in biphasic concave upward free energy correlation with Y. A stepwise mechanism with a rate-limiting leaving group departure from the intermediate involving a predominant frontside attack hydrogen bonded, four-center-type transition state is proposed based on the positive sign of ${\rho}_{XY}$ and primary normal deuterium kinetic isotope effects.

• The KIPS Transactions:PartB
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• v.10B no.7
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• pp.811-814
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• 2003

In this paper, we propose a fast block-matching motion estimation method using the cross pattern and the hexagonal pattern. For the block-matching motion estimation method, full search finds the best motion estimation, but it requires huge search time because it has to check every search point within the search window. The proposed method makes use of the fact that most of motion vectors lie near the center of block. The proposed method first uses the cross pattern to search near the center of block, and then uses the hexagonal pattern to search larger motion vectors. Experimental results show that our method is better than recently proposed search algorithms in terms of mean-square error performance and required search time.

• International Journal of High-Rise Buildings
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• v.2 no.3
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• pp.229-244
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• 2013

Twenty six pressure models of high rise buildings with various cross-sections including twisted models were tested in a boundary layer wind tunnel. The cross-sections were triangular, square, pentagon, hexagon, octagon, dodecagon, circular, and clover. This study investigates variations in peak pressures, and effects of various cross-sections and twist angles on peak pressures. To study the effects of various configurations and twist angles on peak pressures in detail, maximum positive and minimum negative peak pressures at each measurement point of the building for all wind directions are presented and discussed. The results show that peak pressures greatly depend on building cross-section and twist angle.

• Structural Engineering and Mechanics
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• v.71 no.2
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• pp.153-163
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• 2019

Longitudinal fracture behavior of non-linear elastic beam configurations is studied in terms of the strain energy release rate. It is assumed that the beams exhibit continuous material inhomogeneity along the width as well as along the height of the crosssection. The Ramberg-Osgood stress-strain relation is used for describing the non-linear mechanical behavior of the inhomogeneous material. A solution to strain energy release rate is derived that holds for inhomogeneous beams of arbitrary cross-section under combination of axial force and bending moments. Besides, the solution may be applied at any law of continuous distribution of the modulus of elasticity in the beam cross-section. The longitudinal crack may be located arbitrary along the beam height. The solution is used to investigate a longitudinal crack in a beam configuration of rectangular cross-section under four-point bending. The crack is located symmetrically with respect to the beam mid-span. It is assumed that the modulus of elasticity varies continuously according a cosine law in the beam cross-section. The longitudinal fracture behavior of the inhomogeneous beam is studied also by applying the J-integral approach for verification of the non-linear solution to the strain energy release rate derived in the present paper. Effects of material inhomogeneity, crack location along the beam height and non-linear mechanical behavior of the material on the longitudinal fracture behavior are evaluated. Thus, the solution derived in the present paper can be used in engineering design of inhomogeneous non-linear elastic structural members to assess the influence of various material and geometrical parameters on longitudinal fracture.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.47.2-47.2
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• 2021

Focusing on both small separations and baryonic acoustic oscillation scales, the cosmic evolution of the clustering properties of peak, void, wall, and filament-type critical points is measured using two-point correlation functions in ΛCDM dark matter simulations as a function of their relative rarity. A qualitative comparison to the corresponding theory for Gaussian random fields allows us to understand the following observed features: (i) the appearance of an exclusion zone at small separation, whose size depends both on rarity and signature (i.e. the number of negative eigenvalues) of the critical points involved; (ii) the amplification of the baryonic acoustic oscillation bump with rarity and its reversal for cross-correlations involving negatively biased critical points; (iii) the orientation-dependent small-separation divergence of the cross-correlations of peaks and filaments (respectively voids and walls) that reflects the relative loci of such points in the filament's (respectively wall's) eigenframe. The (cross-) correlations involving the most non-linear critical points (peaks, voids) display significant variation with redshift, while those involving less non-linear critical points seem mostly insensitive to redshift evolution, which should prove advantageous to model. The ratios of distances to the maxima of the peak-to-wall and peak-to-void over that of the peak-to-filament cross-correlation are ~2-√~2 and ~3-√~3WJ, respectively, which could be interpreted as the cosmic crystal being on average close to a cubic lattice. The insensitivity to redshift evolution suggests that the absolute and relative clustering of critical points could become a topologically robust alternative to standard clustering techniques when analysing upcoming surveys such as Euclid or Large Synoptic Survey Telescope (LSST).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.421-430
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• 2006

In this paper, we propose a practical implementation of network-adaptive HD(high definition) MPEG-2 video streaming with a cross-layered channel monitoring(CLM) over the IEEE 802.11a WLAN(wireless local area network). For wireless channel monitoring, AP(access point) periodically measures the MAC(medium access control) layer transmission information and sends the monitoring information to a streaming server. This makes that the streaming server reacts more quickly as well as efficiently to the fluctuated wireless channel than that of the end-to-end monitoring(E2EM) scheme for the video adaptation. The streaming sewer dynamically performs the priority-based frame dropping to adjust the video sending rate according to the measured wireless channel condition. For this purpose, our streaming system nicely provides frame-based prioritized packetization by using a real-time stream parsing module. Various evaluation results over an IEEE 802.11a WLAM testbed are provided to verify the intended QoS adaptation capability The experimental results show that the proposed system can effectively mitigate the quality degradation of video streaming caused by the fluctuations of time-varying wireless channel condition.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.301-308
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• 2013

In this paper, an accuracy analysis of parallel method based on non-overlapping domain decomposition method is carried out. In this approach, proposed by Tak et al.(2013), the decomposed subdomains do not overlap each other and the connection between adjacent subdomains is determined via simple connective finite element named interfacial element. This approach has two main advantages. The first is that a direct method such as gauss elimination is available even in a singular problem because the singular stiffness matrix from floating domain can be converted to invertible matrix by assembling the interfacial element. The second is that computational time and storage can be reduced in comparison with the traditional finite element tearing and interconnect(FETI) method. The accuracy of analysis using proposed method, on the other hand, is inclined to decrease at cross points on which more than three subdomains are interconnected. Thus, in this paper, an accuracy analysis for a novel non-overlapping domain decomposition method with a variety of subdomain numbers which are interconnected at cross point is carried out. The cause of accuracy degradation is also analyze and establishment of countermeasure is discussed.