• Journal of Institute of Control, Robotics and Systems
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• v.6 no.3
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• pp.291-297
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• 2000

This paper presents an attitude determination algorithm for the local level strapdown inertial navigation where the body the earth and the transport rate can be calculated separately using a DCM computation scheme, Also presented is a velocity determination algorithm taking into account the attitude variation caused by he change of the navigation frame. The proposed algorithm are implemented using three samples of the velocity and the angle within the integration interval.

• Tribology and Lubricants
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• v.24 no.6
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• pp.343-348
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• 2008

In this paper, a CFD (Computational fluid dynamics) code, FLUENT is adopted to investigate accurate flow characteristics for a slipper bearing which is used swash plate type hydraulic axial piston pump. Static pressure and velocity distributions, and velocity vectors are plotted for different film thickness and slipper rotational velocity. In recess region, there exists a doughnut shaped vortex ring. The static pressure distributions are non-uniform and the flow fields are highly asymmetrical under bearing rotation. Therefore the numerical method adopted in this paper can be use in design of hydrostatic components and further studies are required.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.709-712
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• 1988

Ultrasonic Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. CW(Continuous-Wave) Doppler System uses quadrature detection and phase rotation method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time-domain, had been fabricated. But time-domain analyzing such as audio evaluation and zero- crossing detection for instantaneous and mean frequnecy measurement do not provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency-domain technique to improve system performance. In this paper, we describe a unit which is composed of CW Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of Blood signal.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.71.1-71.1
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• 2014

To investigate physical properties of Solar pores, we use SDO/HMI data from 2010 to 2013. For this, we select single and isolated pores from the active region (Axx, Bxo, Bxi and Bxc-type) listed in Solar Region Summary. Pore is defined by connected pixels satisfying the intensity threshold from pixel of minimum intensity. We try to obtain area, intensity, magnetic field, and Doppler velocity of pores from HMI data. After removing the effects of orbital motion of the SDO satellite and differential rotation of the Sun, we identify that significant daily variations of Doppler velocity with non-zero ordinates still remain in the umbral region, and the artifact is quite dependent on the strength of magnetic field and radial component of velocity of SDO satellite. In this study we develope empirical model to remove the artifact. A preliminary result on the elimination of the artifact will be presented.

• Steel and Composite Structures
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• v.38 no.2
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• pp.141-150
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• 2021

In the present paper we have investigated the Stoneley wave propagation at the interface of two dissimilar homogeneous nonlocal magneto-thermoelastic media under the effect of hall current applied to multi-dual-phase lag heat transfer. The secular equations of Stoneley waves have been derived by using appropriate boundary conditions. The wave characteristics such as attenuation coefficients, temperature distribution and phase velocity are computed and have been depicted graphically. Effect of nonlocal parameter and hall effect are studied on the attenuation coefficient, phase velocity, temperature distribution change, stress component and displacement component. Also, some particular cases have been discussed from the present study.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.43.4-43.4
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• 2021

One of the most promising secondary target programmes of DESI is the peculiar velocity survey, which will notably improve the measurements of cosmology parameters in the low-redshift universe. We use the Fundamental plane and Tully-Fisher relation as distance indicators to calculate peculiar velocities for DESI. This required additional observations to obtain spectra with sufficient quality to measure the velocity dispersions in the case of the fundamental plane, and to get off-centre redshift measurements to reconstruct the rotation curve in the case of the Tully-Fisher relation. However, we devised a clever strategy for suitable target galaxies, that takes advantage of the spare fibres of DESI to gather the required additional data without causing conflicts with the main survey programmes. We provide a brief overview of the preliminary results and success rate based on the first measurements obtained during survey validation as well as an outlook on expected improvements in the fσ₈ measurements once the survey has been completed.

• International journal of advanced smart convergence
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• v.13 no.2
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• pp.103-109
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• 2024

A nonlinear numerical analysis of orientation and velocity fields of the full Ericksen-Leslie theory for a nematic liquid crystal under shear flow is given. We obtained for the first time the three-dimensional orientation and two component velocity profiles evolutions for both in- and out-of-shear plane orientation anchorings. Complex evolution routes to steady state were found even for shear aligning nematic. As the Ericksen number increases monotonic evolution of velocity and orientation shifts towards multi-region nucleating director rotation growth with complex secondary flow generations. We found that contrary to the in-shear-plane anchorings like homeotropic or parallel anchorings, binormal anchoring gives rise to substantial non-planar three-dimensional orientation with nonzero secondary flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.12
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• pp.1193-1199
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• 2012

A cup burner experiment was performed to investigate the effect of the oxidizer velocity and concentration on flame instability near extinction. Heptane was used as a fuel and air diluted by nitrogen and carbon dioxide was used in the oxidizer stream. Two types of flame instabilities at the flame base and at axial downstream were observed near extinction. The instability at the flame base could be characterized by cell, swing, and rotation modes, and the cell mode changed to the rotation mode through the swing mode as the oxidizer velocity increased. To assess the parameters for the flame instability, the initial mixture strengths, Lewis number, and adiabatic flame temperature were investigated under each condition. The Lewis number might be the most important among them, but it is impossible to generalize because of the insufficient number of cases. Furthermore, the axial periodic flickering motion disappeared at low and high oxidizer velocities near extinction. This resulted from the fact that low oxidizer velocity induced evaporated fuel velocity below the critical velocity and high velocity made the reacting fuel velocity comparable.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.395-402
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• 2000

This paper presents the improvement for speed characteristics of a Brushless DC Motor (BLDCM), it was applied to digital PI control for this. The practical PID control has been widely used to velocity control of DC motors. In this paper, a digital PI controller is used in order to decrease the speed error in constant velocity control of BLDCM. A TMS320C31 DSP is used for the microprocessor of digital PI control. The method using the DSP carry out the real-time control. The DSP has the rapid calculation ability and sampling time used lms. Driving BLDCM used 50W, motor input DC 150V and rotation speed 3000rpm. When BLDCM is to approval for discretion velocity at the acceleration and deceleration driving with any load, it was a feasible for stabilization control. Therefore, the experimental results indicate the superiority and validity of the velocity control by digital PI control.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.42.1-42.1
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• 2017

We present the results from an extensive spectroscopic survey of the central region of the nearby galaxy cluster Abell 2199 (A2199) at z=0.03. By combining 775 new redshifts from the MMT/Hectospec observations with the data in the literature, we construct a large sample of 1624 galaxies with measured redshifts at R<30', which redsults in high spectroscopic completeness at $r_{petro,0}$<20.5 (77%). We use these data to study the kinematics and clustering of galaxies, focusing on the comparison with those of the intracluster medium (ICM) from Suzaku X-ray observations. We identify 406 member galaxies of A2199 at R<30' using the caustic technique. The velocity dispersion profile of cluster members appears smoothly connected to the stellar velocity dispersion profile of the cD galaxy. The luminosity function is well fitted with a Schechter function at $M_r$<-15. The radial velocities of cluster galaxies generally agree well with those of the ICM, but there are some regions where the velocity difference between the two is about a few hundred kilometers per second. The cluster galaxies show a hint of global rotation at R<5' with $v_{rot}=300-600kms^{-1}$, but the ICM in the same region does not show such rotation. We apply a friends-of-friends algorithm to the cluster galaxy sample at R<60' and identify 32 group candidates, and examine the spatial correlation between the galaxy groups and X-ray emission. This extensive survey in the central region of A2199 provides an important basis for future studies of interplay among the galaxies, the ICM, and the dark matter in the cluster.