• Journal of the Institute of Convergence Signal Processing
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• v.20 no.3
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• pp.171-176
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• 2019

Drones are highly utilized because they can efficiently acquire long-distance videos. In drone operation, the speed, which is the magnitude of the velocity, can be set, but the moving direction cannot be set, so accurate information about the drone's movement should be estimated. In this paper, we estimate the velocity of the drone moving at a constant speed and direction. In order to estimate the drone's velocity, the displacement of the target frame to minimize the sum of absolute difference (SAD) of the reference frame and the target frame is obtained. The ground truth of the drone's velocity is calculated using the position of a certain matching point over all frames. In the experiments, a video was obtained from the drone moving at a constant speed at a height of 150 meters. The root mean squared error (RMSE) of the estimated velocities in x and y directions and the RMSE of the speed were obtained showing the reliability of the proposed method.

• Clinical and Experimental Pediatrics
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• v.49 no.11
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• pp.1202-1210
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• 2006

Purpose : A quantitative and easily measured Doppler index of combined systolic and diastolic ventricular myocardial performance (Tei index) was recently proposed as a potentially useful predictor of global myocardial performance. However, presence of heart rate fluctuation makes it unreliable. Therefore, the modified Tei index was introduced by using tissue Doppler imaging (TDI) which enables measuring contraction and relaxation velocities from myocardium simultaneously. The purpose of this study was to investigate the effectiveness of the modified Tei index in the evaluation of global cardiac function. Methods : Forty eight patients in the acute phase of Kawasaki disease (KD) were studied. These patients were divided into two groups according to the modified Tei index. TDI and conventional echocardiography were performed. Systolic velocity, systolic displacement, E' velocity, E' displacement, A' velocity and A' displacement were measured at the base, mid-septum and the apex of the interventricular septum. Ejection fraction (EF), Tei index and modified Tei index were estimated. Results : Modified Tei index correlated negatively with systolic displacement, E' displacement and A' displacement at the base. Modified Tei index correlated positively with ESR and CRP. EF and Tei index were normal in KD patients. Conclusion : Modified Tei index is a safe, feasible and sensitive index for evaluating global ventricular functions in spite of normal EF and Tei index in KD.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.36-39
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• 2005

Information on temporal evolution of whole velocity fields is essential for physical understanding of a complicated turbulent flow and was obtainable using dynamic PIV because of advances of high-speed imaging technique, laser and electronics. A dynamic PIV systme consists of a high-speed CMOS camera having $1K\times1K$ pixels resolution at 1 KHz and a high-repetition Nd:Yag pulse laser. In order to validate its performance, the dynamic PIV system was applied to a turbulent jet whose Reynolds number is about 3000. The particle images of $1024\times512$ pixels were captured at a sampling rate of 4 KHz. The dynamic PIV system measured successfully the temporal evolution of instantaneous velocity fields of the turbulent jet, from which spectral analysis of turbulent structure was also feasible.

• ETRI Journal
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• v.27 no.2
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• pp.172-180
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• 2005

Image resampling according to epipolar geometry is an important prerequisite for a variety of photogrammetric tasks. Established procedures for resampling frame images according to epipolar geometry are not suitable for scenes captured by line cameras. In this paper, the mathematical model describing epipolar lines in scenes captured by line cameras moving with constant velocity and attitude is established and analyzed. The choice of this trajectory is motivated by the fact that many line cameras can be assumed to follow such a flight path during the short duration of a scene capture (especially when considering space-borne imaging platforms). Experimental results from synthetic along-track and across-track stereo-scenes are presented. For these scenes, the deviations of the resulting epipolar lines from straightness, as the camera's angular field of view decreases, are quantified and presented.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.85-86
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• 1996

The imaging spectroscopic observations of the Magellanic irregular galaxy NGC 4449 were made to show the detailed kinematic structure of the galaxy. Many filamentary structures and Several bubble-like structures are recognized in a 3D data cube of H$\alpha$ emission line. Velocity field shows the kpc-scale mosaic structure and counter- rotation of ionized gas.

• Journal of Veterinary Clinics
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• v.34 no.4
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• pp.268-271
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• 2017

A 1.3 year-old Castrated male Bedlington terrier (10.0 kg of body weight) was presented with heart murmur and occasional coughing. Diagnostic imaging studies revealed supravalvular pulmonic stenosis (maximal velocity 2.91 m/s) from abnormal membranous structure (aperture) distal to the pulmonary valve in the main pulmonary artery. Further study also revealed pulmonic regurgitant (1.82 m/s of peak velocity, 13.2 mmHg of pressure gradient) jets started from the abnormal membranous structure. Since the dog had no obvious clinical signs related to heart failure, no interventional therapy including balloon dilation was considered in this case. Instead, medical treatment for preventing further deterioration of clinical signs related to PS was done with enalapril. This case report described a rare case of type III supravalvular PS in a dog, which has never been reported. Further deterioration of clinical signs has yet been recognized after medical treatment.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.71.2-71.2
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• 2014

For better understanding of the physics of pores, we have investigated horizontal and vertical motions of plasma in a pore obtained on 2013 August 24 by using high time and spatial resolution data from the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST). We infer the LOS velocity by applying the bisector method to the wings of Ca II 8542 ${\AA}$ profile, and inspect oscillations of the intensity and the LOS velocity in the pore. In this presentation, we discuss the physical implications of our results in view of a connection between LOS and horizontal plasma flows in a concentrated magnetic flux.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.1
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• pp.1-8
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• 2009

Recently microscale biofluid flows have been receiving large attention in various research areas. However, most conventional imaging techniques are unsatisfactory due to difficulties encountered in the visualization of microscale biological flows. Recent advances in optics and digital image processing techniques have made it possible to develop several advanced micro-PIV/PTV techniques. They can be used to get quantitative velocity field information of various biofluid flows from visualized images of tracer particles. In this paper, as new advanced micro-PIV techniques suitable for biofluid flow analysis, the basic principle and typical applications of the time-resolved micro-PIV and X-ray micro-PIV methods are explained. As a 3D velocity field measurement technique for measuring microscale flows, holographic micro-PTV method is introduced. These advanced PIV/PTV techniques can be used to reveal the basic physics of various microscale biological flows and will play an important role in visualizing veiled biofluid flow phenomena, for which conventional methods have many difficulties to analyze.

• Proceedings of the ESK Conference
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• 1996.04a
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• pp.301-306
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• 1996

Different patterns of dynamic trunk performance between normal subjects and low-back pain (LBP) patients have been investigated. Ten healthy subjects and ten LBP patients were recruited for this study. An experiment was designed to quantify the dynamic motion of the back and hip during repetitive flexion/extension of the trunk. The angular velocity, angular acceleration and the phase angle difference between the hip and back were recorded as dependent measures via electro- mechanical devices. Results showed the significant differences in the velocity and acceleration of the hip and back and the phase angle between normal subjects and LBP patients. The consistency of kinematic variables during motion cycles was also examined in terms of variance ratio (Hershler and Milner, 1978). Based on the results of the study, these quantifiable variables such as trunk kinematics and hip-spine coordination can be developed as a medical tool to identify LBP patients in addition to current imaging techniques.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.58.1-58.1
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• 2018

In the solar atmosphere, below the region of temperature minimum, temperature decreases with height and above it, temperature increases with height. Therefore the inference of temperature minimum is a basis of the study about the solar atmosphere and heating problem. The temperature of the temperature minimum region can be inferred from acoustic cutoff frequency. According to a recent study the acoustic cutoff frequency is related to the peak frequency of the power spectrum the chromospheric three-minute velocity oscillations. Using this relationship, we infer the temperature of temperature minimum. The three minute velocity oscillation and its power spectrum are obtained for a pore observed with the Fast Imaging Solar Spectrograph (FISS) $H{\alpha}$ band. We present the inferred temperature and compare it with the temperature of Maltby model. We also investigate the effect of the inclination of magnetic field on the temperature minimum.