• Korean Chemical Engineering Research
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• 제52권1호
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• pp.75-80
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• 2014

The convective flow structures in the vapor phase on earth are shown to be single unicellular, indicating the solutally dominant convection is important. These findings reflect that the total molar fluxes show asymmetrical patterns in a viewpoint of interfacial distributions. With decreasing the gravitational level form $1g_0$ down to $1.0{\times}10^{-4}g_0$, the total molar fluxes decay first order exponentially. It is also found that the total molar fluxes decay first order exponentially with increasing the partial pressure of component B, PB (Torr) form 5 Torr up to 400 Torr. Under microgravity environments less than $1g_0$, a diffusive-convection mode is dominant and, results in much uniformity in front of the crystal regions in comparisons with a normal gravity acceleration of $1g_0$.

• 천문학회지
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• 제23권1호
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• pp.31-42
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• 1990

Fine structures of a quiescent prominence are studied by analyzing high resolution H alpha filtergrams and H alpha line spectra observed at the Hida Observatory of Kyoto University. We have found two kinds of downward motions in the prominence. One of them is a movement with a constant acceleration below the solar gravity(${\simeq}1/4g_s$) and the other with an uniform velocity(${\simeq}16Km/s$). The average life time and the size of prominence knots are estimated to be about 7 minutes and 4000Km, respectively. Spatial and brightness distribution of knots are also presented in this paper. With the analytical solutions derived from magnetostatic equilibrium in the prominence, we have examined the filamentary structure based on the Kippenhahn-Schluter model. Sag angles of the magnetic fields supporting the prominence matter are predicted from the observed density profile.

• 한국안전학회지
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• 제16권3호
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• pp.99-105
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• 2001

This paper presents results km a series of model tests oil vertically loaded single piles to compare the behaviors of H and pipe piles under the same ground condition. The aims of this paper were to compare the bearing capacity of H-pile md pipe piles under in the same ground condition and to estimate the effect of gravity acceleration and relative soil density. Relative density of soil were made to be 40%, 80% and embedded length of pile on sand was increased by 10, 12, 14, 16 times of the diameter of pile, respectively. As a results of test series, allowable load of H-pile is from 6.4% to 18.2% larger than allowable load of pipe pile in relative density 80% and from 9.1% to 39.4% larger than allowable load of pipe pile in relative density 40%. As a results of numerical analysis, we were predicted behaviour of stress-displacement of pile with model test. In the case of relative density 80% and 40%, bearing capacity of H pile represent from 17.74% to 18.6% larger than allowable load of pipe pile.

• 전기학회논문지
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• 제59권7호
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• pp.1309-1313
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• 2010

In this paper, we propose a novel guidance law for controlling an UAV(Unmanned Air-Vehicle) to follow a reference line in vertical plane. A kinematics model representing the relative motion of the UAV to the reference line is derived. And then LQR(Linear Quadratic Regulator) theory is applied to the model to derive the VLFG(Vertical Line Following Guidance) law. The resultant guidance law forms a gain-scheduling controller scheduled by a simple parameter $\sigma$ which is a function of the UAV's velocity, axial acceleration, gravity, and the slope of the reference line. Also derived is a stability condition for the $\sigma$ variation based on Lyapunov theory. Simulation results show that the proposed guidance law can be applied effectively to UAV guidance algorithm design.

• 대한전자공학회논문지
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• 제26권12호
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• pp.2032-2038
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• 1989

Single mode optical fiber interferometeric sensors using phase tracking homodyne detection are typically susceptible to environmentally indured temperature fluctuations and other types of disturbances. A simple and effective phase tracking feedback electronic circuit for compensator is described to achieve stabilizing signal output, maximum sensitivity and linearity in the fiber optic Mach-Zehnder infterferometer in the presence of differential phase drift. The phase tracking range of the piezoelectric cyclinder in the reference arm is \ulcorner.7 \ulcornerad and the prabe mass about 1 gram in the sensing arm was used for measurements of the gravity acceleration.

• 한국결정성장학회지
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• 제13권4호
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• pp.187-198
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• 2003

Zinc selenide (ZnSe) single crystals hold promise for many electro-optics, acousto-optic and green laser generation applications. This material is prepared in closed ampoules by the physical vapor transport (PVT) growth method based on the dissociative sublimation. We investigate the effects of diffusive-convection on the crystal growth rate of ZnSe with a low vapor pressure system in a horizontal configuration. Our results show that for the ratios of partial pressures, s=0.2 and 2.9, the growth rate increases with the Peclet number and the temperature differences between the source and crystal. As the ratio of partial pressures approaches the stoichiometric value of 2, the rate increases. The mass fluk based on one dimensional (1D model) flow for low vapor pressure system fall within the range of the predictions (2D model) obtained by solving the coupled set of conservation equations, which indicates the flow fields would be advective-diffusive. Therefore, the rate and the flow fields are independent of gravity acceleration levels.

• 천문학논총
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• 제30권2호
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• pp.367-369
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• 2015

The FastSound project is a galaxy redshift survey using Subaru/FMOS to detect $H{\alpha}$ emitting galaxies at z ~ 1:3, for the purpose of probing the origin of the accelerated expansion of the universe. The survey has detected ~4,000 galaxy redshifts in a total area of $30deg^2$, and detected the redshift space distortion at this redshift range for the first time. The redshift space distortion (RSD) signal will be used to derive a measurement of the growth rate of large scale structure, which will provide a test for modified gravity as a possible origin of accelerated cosmic explansion. Here we present an overview and the current status of the project.

• 한국통신학회논문지
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• 제17권10호
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• pp.1092-1099
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• 1992

본 논문은 광섬유 가속도기를 이용한 중력가속도$(0{\sim}1G)$의 감도를 보였다. 단일모드 광섬유 Mach-Zehnder 간섭계가 약 1 그람 정도의 probe mass를 이용하여 광섬유 내의 스트레인에 의해 발생된 광로정 변화를 감지하는데 이용 되었다. 본 시스템의 기준 통로내 PZT 원통의 위상 변환 이득은 0.88rad./v로 측정 되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.103-106
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• 2005

This paper reviews the dynamic load phenomenon referred to as 'silo quaking', caused shock vibration and loud noise, during gravity discharge in coal silos. Quaking in tall silo is examined using experimental data obtained from a Coal Power Plant and several experimental and numerical investigations available in the published literature. In the experiment, the acceleration was measured at various height on the silo column and floor and by doing so, not only could the variation of the amplitude of the quaking be observed, but also the propagation of waves could clearly be seen. Through an overview of recent research on this subject, it is shown that the current silo quaking is produced by slip-stick friction between the internal wall of silo and the granular material, i.e. coal.

• 한국산업융합학회 논문집
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• 제22권5호
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• pp.575-582
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• 2019

Advanced driving assist system can support safety of driver and passengers which may require vehicle dynamics states as well as road geometry. It is essential to have in real-time estimation of related variables and parameters. Among the road geometry parameters, road slope angle which can not be measured is essential parameter in pose estimation, adaptive cruise control and others on sag road. In this paper, Kalman filter based method for the estimation of the vehicle dynamics and road slope angle using a nonlinear vehicle model is proposed. It uses a combination of Kalman filter as Cascade Extended Kalman Filter. CEKF uses measured vehicle states such as yaw rate, longitudinal/lateral acceleration and velocity. Unknown vehicle parameters such as center of gravity and inertia are obtained by 2 D.O.F lateral model and experimentally. Simulation and Experimental tests conducted with commercialized vehicle dynamics model and real-car.