• The Journal of the Korea Contents Association
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• v.16 no.10
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• pp.514-521
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• 2016

The High Efficiency Video Coding (HEVC) standard provides superior coding efficiency by utilizing highly flexible block structure and more diverse coding modes. However, rate-distortion optimization (RDO) process for the decision of optimal block size and prediction mode requires excessive computational complexity. To alleviate the computation load, this paper proposes a new moment-based fast CU size decision algorithm for intra coding in HEVC. In the proposed method, moment values are computed in each CU block to estimate the texture complexity of the block from which the decision on an additional CU splitting procedure is performed. Unlike conventional methods which are mostly variance-based approaches, the proposed method incorporates the third-order moments of the CU block in the design of the fast CU size decision algorithm, which enables an elaborate classification of CU types and thus improves the RD-performance of the fast algorithm. Experimental results show that the proposed method saves 32% encoding time with 1.1% increase of BD-rate compared to HM-10.0, and 4.2% decrease of BD-rate compared to the conventional variance-based fast algorithm.

• Journal of Biomedical Engineering Research
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• v.36 no.2
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• pp.43-47
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• 2015

Osteoarthritis is the most common chronic joint disease in the world. With its progression, cartilage thickness tends to diminish, which causes severe pain to human being. One way to examine the stage of osteoarthritis is to measure the cartilage thickness. When it comes to inter-subject study, however, it is not easy task to compare cartilage thickness since every human being has different cartilage structure. In this paper, we propose a method to assess cartilage defect using MRI inter-subject thickness comparison. First, we used manual segmentation method to build accurate atlas images and each segmented image was labeled as articular surface and bone-cartilage interface in order to measure the thickness. Secondly, each point in the bone-cartilage interface was assigned the measured thickness so that the thickness does not change after registration. We used affine transformation and SyGN to get deformation fields which were then applied to thickness images to have cartilage thickness atlas. In this way, it is possible to investigate pixel-by-pixel thickness comparison. Lastly, the atlas images were made according to their osteoarthritis grade which indicates the degree of its progression. The result atlas images were compared using the analysis of variance in order to verify the validity of our method. The result shows that a significant difference is existed among them with p < 0.001.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.10
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• pp.1382-1387
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• 2017

Objective: During the last decade, genetic evaluation of dairy cows using longitudinal data (test day milk yield or 305-day milk yield) using random regression method has been officially adopted in several countries. The objectives of this study were to estimate covariance functions for genetic and permanent environmental effects and to obtain genetic parameters of 305-day milk yield over seven parities. Methods: Data including 60,279 total 305-day milk yield of 17,309 Iranian Holstein dairy cows in 7 parities calved between 20 to 140 months between 2004 and 2011. Residual variances were modeled by homogeneous and step functions with 7 and 10 classes. Results: The results showed that a third order polynomial for additive genetic and permanent environmental effects plus a step function with 10 classes for the residual variance was the most adequate and parsimonious model to describe the covariance structure of the data. Heritability estimates obtained by this model varied from 0.17 to 0.28. The performance of this model was better than repeatability model. Moreover, 10 classes of residual variance produce the more accurate result than 7 classes or homogeneous residual effect. Conclusion: A quadratic Legendre polynomial for additive genetic and permanent environmental effects with 10 step function residual classes are sufficient to produce a parsimonious model that explained the change in 305-day milk yield over consecutive parities of Iranian Holstein cows.

• International Journal of Automotive Technology
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• v.3 no.1
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• pp.27-32
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• 2002

Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions fur passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed. It is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper which offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-offbecomes smooth when the fixed orifice size increases. Damping forces are measured with the change of the solenoid current at the different piston velocities to confirm the maximum hysteresis of 20N, linearity, and variance of damping farce. The damping farce variance is wide and continuous, and is controlled by the spoof opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.248-254
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• 1991

The demersal fishes of Asan Bay were collected by an otter trawl in August 1990 to determine optimum sample size for the analysis of community structure. A total of 17 species comprising 957 individuals and 21,840 grams in biomass was collected. Predominant species were Cynoglossus joyneri, Thrissa koreana, Hexagrammos otakii and Johnius belengerii. Coefficients of variation for fish numbers in ten replicate tows ranged from 2.2 to $385.1\%$ for four abundant species and from 52.2 to $162.0\%$ when all species were considered. The cumulative number of species increased rapidly until 4 hauls, and less than 1 species per haul in average was added thereafter. The cumulative diversity index reached nearly an asymptote value when three of samples were combined. Variance in the number of individuals diminished as the sample size increased. The ratio of variance to mean numbers (dispersion index) was not significantly different from the unity when first 4-haul samples were combined. Four of 20-minute trawl haul are proposed to be a proper sampling size for the unbiased estimation of abundance in the study area.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.12
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• pp.1112-1115
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• 2015

Recently, there have been advancements in radar related material technology, circuit design techniques and architecture design techniques. These have led to developments in radars' performance while decreasing the costs. Many studies have been carried out to apply radars to multipurpose application. In this study, a reconfigurable S-/X- band radar structure for multipurpose application is proposed and implemented. This radar measures a $51.2cm{\times}50.6cm$ target for 10 times from 2 m to 6 m range with 0.25 m distance step. The measured results show that this radar has 26.40 cm maximum range error, 5.63 cm average range error, and 0.24 cm range error variance at S-band while it has 8.53 cm maximum range error, 2.52 cm average range error, and 0.04 cm range error variance at X-band.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.713-720
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• 2018

The Signal Intelligence (SIGINT) system based on Angle-of-Arrival(AOA) estimation, interference suppression, and transmission beamforming techniques is a cutting edge technology for efficiently collecting various signal information. In this paper, we present the efficient structure of a satellite system consisted of an AOA estimator, an adaptive beamformer, a signal processing and D/B unit, and a transmission beamformer, for collecting signal information. For accurately estimating AOAs of various signals, efficiently suppressing interference or jamming signals, and efficiently transmitting the collected information or data, we employ Multiple Signal Classification (MUSIC), Minimum Variance Distortionless Response (MVDR), and Minimum Mean Square Error (MMSE) algorithms, respectively. Also, we evaluate and analysis the performance of the presented satellite system through the computer simulation.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1207-1212
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• 2018

The signal intelligence (SIGINT) technology is actively used for collecting various data, in a number of fields, including a military industry. In order to collect the signal information and data and to transmit/receive the collected data efficiently, the accurate angle-of-arrival (AOA) information is required and communication disturbance from the interference or jamming signal should be minimized. In this paper, we present the structure of an adaptive beam-forming satellite system based on the planar array antenna, for collecting and transmitting/receiving the signal information and data efficiently. The presented adaptive beam-forming system consists of an antenna in the form of a planar array, an AOA estimator based on the Multiple Signal Classification (MUSIC) algorithm, an adaptive Minimum Variance Distortionless Response (MVDR) interference canceler, a signal processing and D/B unit, and a transmission beamformer based on Minimum mean Square Error (MMSE). In addition, through the computer simulation, we evaluate and analyze the performance of the proposed system.

• Phonetics and Speech Sciences
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• v.10 no.4
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• pp.127-134
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• 2018

This study aims to explain the difficulties children with articulation and phonological disorders have in producing alveolar fricative sounds. The study will perform a comparative analysis revealing how ordinary children produce alveolar fricative sounds through five different acoustic variables, and consequently identifying objective differences, compared to children with articulation and phonological disorders. Therefore, this study compared and analyzed the differences between 10 children with articulation and phonological disorders and 10 ordinary children according to a phonation type of alveolar fricative sounds (/s/ and /$s^*$), a type of vowel (/i/, /ε/, /u/, /o/, /ɯ/, /ʌ/, /ɑ/), and a structure of syllables (CV, VCV) through acoustic variables including a central moment, skewness, kurtosis, a center of gravity and variance. That is, children with articulation and phonological disorders, when compared to ordinary children, have difficulties with concentrating an agile and momentary friction with strength when articulating alveolar fricative sounds, which uses strong energy and accompany tension. Furthermore, the values of alveolar fricative sounds of children with articulation and phonological disorders appeared to spread evenly over the average range, which means that the range of overall the standard deviation values for children with functional phonological disorders is wider than that of ordinary children. For a future study, if the mispronounced sounds relating to omission, substitution, and addition can be compared and analyzed for various target groups, it could be used effectively to help children with functional phonological disorders.

• Current Optics and Photonics
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• v.8 no.1
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• pp.38-44
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• 2024

Under the influence of atmospheric turbulence, a star's point image will shake back and forth erratically, and after exposure the originally small star point will spread into a huge spot, which will affect the ground calibration of the star sensor. To analyze the impact of atmospheric turbulence on the positioning accuracy of the star's center of mass, this paper simulates the atmospheric turbulence phase screen using a method based on a sparse spectrum. It is added to the static-star-simulation device to study the transmission characteristics of atmospheric turbulence in star-point simulation, and to analyze the changes in star points under different atmospheric refractive-index structural constants. The simulation results show that the structure function of the atmospheric turbulence phase screen simulated by the sparse spectral method has an average error of 6.8% compared to the theoretical value, while the classical Fourier-transform method can have an error of up to 23% at low frequencies. By including a simulation in which the phase screen would cause errors in the center-of-mass position of the star point, 100 consecutive images are selected and the average drift variance is obtained for each turbulence scenario; The stronger the turbulence, the larger the drift variance. This study can provide a basis for subsequent improvement of the ground-calibration accuracy of a star sensitizer, and for analyzing and evaluating the effect of atmospheric turbulence on the beam.