• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.60-65
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• 1994

In this study, the dynamic characteristics of a turbine-meter-type flowmeter is investigated by making use of the remote instantaneous flow rate measurement method (RIFM). The results of the frequency response test indicated that the gain of the flow rate of the turbine-meter-type flowmeter relative to the flow rate of the RIFM was nearly unity up to 40Hz and the phase lag of the flow rate became 90 degrees at 70Hz.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.192-197
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• 1992

The position error in multi-axis machine tools are due to many elements, such as the static friction, servo lag, a nonlinear disturbance, the gain mismatch between multi-axis controllers. In the work, modeling for the plant was carried out through the velocity response by the step input signal. Digital PI controllers, LQ optimal controllers and feedforward controllers are designed for a high tracking performance based on the model. The results of experimentation showed that the controllers worked properly.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.642-646
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• 1992

Trajectory tracking control problems are described for a two-link robot manipulator with artificial rubber muscle actuators. Under the assumption that the so-called independent joint control is applied to the control system, the dynamic model for each link is identified as a linear second-order system with time-lag by the step response. Two control laws such as the feedforward and the computed torque control methods, are experimentally applied for controlling the circular trajectory of an actual robot manipulator.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.3
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• pp.485-492
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• 1994

Trajectory tracking control porblems are described for a two-link robot manipulator with artificial rubber muscle actuators. Under the assumption that the so-called independent joint control is applied to the control system, the dynamic model for each link is identified as a linear second-order system with time-lag by the step response. Two control laws such as the feedforward and the computed torque control methods, are experimentally applied for controlling the circular trajectory of an actual robot mainpulator.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.699-705
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• 2002

The present study discusses the deviation from the pure dead-time model of passive scalars such as temperature and concentration in the Poiseulle flow Even in the case of no thermal diffusion, there exists a substantial amount of damping and large deviation of phase lag from that computed by the traditional dead-time model after only 10 diameter downstream. These are caused by the phase difference of temperature in the radial direction due to the nonuniform velocity distribution. In the presence of thermal diffusion, damping is more pronounced.

• 전기의세계
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• v.19 no.6
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• pp.1-7
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• 1970

In this paper, to determine process dynamic characteristics, the correlation method for measuring the impulse response of process using a pseudo-random binary signal as the test signal instead of white noise was studied. The error caused by using the signal of Mesquence signal generator which was built up by the authors was analysed. Experments were performed on the 1st and 2nd order lag systems and the results were in good coincidence with theoretical values. It is expected that applying these results, it may be possible to develop a continuous measuring method adaptable to modern control systems.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.271-298
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• 2016

In this paper, we study a problem of passive suppression of helicopter Ground Resonance (GR) using a single degree freedom Nonlinear Energy Sink (NES), GR is a dynamic instability involving the coupling of the blades motion in the rotational plane (i.e. the lag motion) and the helicopter fuselage motion. A reduced linear system reproducing GR instability is used. It is obtained using successively Coleman transformation and binormal transformation. The analysis of the steadystate responses of this model is performed when a NES is attached on the helicopter fuselage. The NES involves an essential cubic restoring force and a linear damping force. The analysis is achieved applying complexification-averaging method. The resulting slow-flow model is finally analyzed using multiple scale approach. Four steady-state responses corresponding to complete suppression, partial suppression through strongly modulated response, partial suppression through periodic response and no suppression of the GR are highlighted. An algorithm based on simple criterions is developed to predict these steady-state response regimes. Numerical simulations of the complete system confirm this analysis of the slow-flow dynamics. A parametric analysis of the influence of the NES damping coefficient and the rotor speed on the response regime is finally proposed.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.2
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• pp.9-14
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• 2009

Purpose: The purpose of this study was to examine the relationship between the accommodative facility, blink rate and accommodative lag according to the change of angles of main viewpoint of near distance worker and study an appropriate viewing angle that mitigates asthenopia, such as headaches or eye fatigue accompanied when reading and staring at the computer or TV for a long time. Methods: Total of 27 people including 12 male university students and 15 female university students in the age of 20 to 36 with frequent near distance works, such as computers, were selected to study the accommodative facility, the blink rate and the accommodative lag in accordance with the change of viewing angles of the near distance workers. The refraction error was corrected completely and the phoropter was shifted to near distance mode to locate the near distance indication at 40 cm. The accommodative facility and the blink rate were measured for one minute at each viewing direction of $40^{\circ}$ downward, $20^{\circ}$ downward, horizontal, and $20^{\circ}$ upward directions based on the horizontal line and the accommodative lag was measured in dynamic retinoscopy using retinoscope. Results: As a result, when the main viewpoint was moved on upper direction from the $40^{\circ}$ below, the accommodative facility was reduced and the blink rate and the accommodative lag were increased so their eyes became dry and the accommodation response was reduced. Conclusions: In near distance works, the eye fatigue level can be minimized by locating a book or a computer screen $40^{\circ}$ below than the horizontal direction.

• The Korean Journal of Community Living Science
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• v.26 no.1
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• pp.75-85
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• 2015

This study investigates the impact of livestock diseases, including FMD(foot-and-mouth disease) and MCD(mad-cow disease), on pork demand in Korea. TV news stories about the livestock diseases were considered as negative advertising, and therefore the carry-over effect of negative advertising was combined with the pork demand model in conjunction with an exponential distributed lag function. The asymmetry hypothesis was imposed, however it was accepted that demand response does not show different sensitivities to increases and decreases in the livestock disease news. FMD news had a negative effect on pork demand, whereas MCD news had a positive effect, yet FMD news had a greater effect on pork demand than MCD news. The pork demand elasticity estimates for FMD and MCD news were -0.0071 and 0.0028, respectively. The cross-elasticity of the imported beef price to pork demand was highly inelastic, but it was elastic during the beef import embargo.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.219-228
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• 2020

The study investigates the impact of inflation rate on economic growth to find the best-fit model for economic growth in Vietnam. The study applied Vector Autoregressive (VAR), cointegration models, and unit root test for the time-series data from 1996 to 2018 to test the inflation impact on the economic growth in the short and long term. The study showed that the two variables are stationary at lag first difference I(1) with 1%, 5% and 10%; trace test indicates two cointegrating equations at the 0.05 level, the INF does not granger cause GDP, the optimal lag I(1) and the variables are closely related as R2 is 72%. It finds that the VAR model's results are the basis to perform economic growth; besides, the inflation rate is positively related to economic growth. The results support the monetary policy. This study identifies issues for Government to consider: have a comprehensive solution among macroeconomic policies, monetary policy, fiscal policy and other policies to control and maintain the inflation and stimulate growth; set a priority goal for sustainable economic growth; not pursue economic growth by maintaining the inflation rate in the long term, but take appropriate measures to stabilize the inflation at the best-fitted VAR forecast model.