• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.10
• /
• pp.1757-1762
• /
• 2007

Recently, the demand for the low cost power conversion equipment is rapidly increased. To develop this three phase voltage source inverter, optimum power conversion equipment to system is designed. The optimum operation method to minimize the power loss also satisfy the life time of the power electronics that is request in the present industry. In this paper, the efficient operating method to change of the acceleration, jerk, and switching frequency in the interval of acceleration is selected to optimize the power loss and life time of the power electronics by using the elevator model. So, we proposed the method that 50[A] rating power electronics is adopted in 9[kW] load.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.352-356
• /
• 1998

This paper is a study about Ac servo motor position and speed control characteristics which depend on feedforward control, the acceleration / deceleration time constant after the interpolation, and PI control, automatic deceleration at corner in order to shape cutting control of feed drive system of the machine tool. The shape error caused by delay of the servo system in the direction of radius at the time of circular cutting is reduced by feedforward control. The shape error generated by the position command delay is minimized by using the acceleration / deceleration time constant after the interpolation. The results were verified to optical machining center experimentation of the machine tool.

• International Journal of Automotive Technology
• /
• v.3 no.3
• /
• pp.101-109
• /
• 2002

A time domain method for solving nonstationary random vibration caused by vehicle acceleration is first proposed in which a time changing model is established for representing nonstationary excitation of a rough road. Furthermore a novel frequency domain method called the transient power spectral density with spatial frequency (TPSD) is presented to obtain a response of vehicle system in frequency domain. This method has been proved to be valid by comparing numerical results with the exact solution.

• Proceedings of the KIEE Conference
• /
• 2001.11b
• /
• pp.73-76
• /
• 2001

This paper presents a new systematic contingency selection, screening and ranking method for on-line transient security assessment. Transient stability of a particular generator is influenced most by fault near it. Fault at the transmission lines adjacent to the generators are selected as contingency. Two screening methods are developed using the sensitivity of modal synchronizing torque coefficient and computing an approximate critical clearing time(CCT) without time simulation. The first method, which considers only synchronizing power, may mislead in some cases since it does not consider the acceleration power. The approximate CCT method, which consider both the acceleration and deceleration power, worked well. Finally the Single Machine Equivalent(SIME) method is implemented using IPLAN of PSS/E for detailed stability analysis.

• Publications of The Korean Astronomical Society
• /
• v.11 no.1
• /
• pp.57-73
• /
• 1996

As a continuing effort to develop an automatic control system for small telescope, we developed the software for telescope control and CCD observations under DOS operating system. For accurate pointing of the telescope in short amount of time, we modelled the angular speed of the telescope by aquadratic function of time (constant acceleration) for the first 15 second and then linear function of time (zero acceleration) aftwewards. By changing the telescope speed from 'slew' to 'fine' before the telescope reaches the desired position, we could achieve the accuracy of a few arcsecond. The CCD control software was written for model CCD-10 of CCD Technology. This CCD can be used for guiding purposes. We also conducted the study for remote control of the telescope using telephone line. Although it cannot be used for real observations at the present form, we succeded in remotely pointing the telescope to desired direction. As faster communication technologies become widely available, simple observations can be made remotely in the near future. Finally we report some observational results made with the present control system.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.1
• /
• pp.139-145
• /
• 1996

The input estimation method estimates maneuvering input acceleration in order to track a maneuvering target. In this paper, the optimal input estimator is derived by choosing the MAP hypothesis among maneuvering input transition hypotheses under the assumption that a maneuvering input acceleration is a semi-Markov process. The optimal input estimation method cannot be realized because the optimal filter should consider every maneuver onset time hypothesis from filter starting time to current time which increase rapidly. Hence the suboptimal filter using a sliding window is proposed. Since the proposed method can consider all hypotheses of input transitions inside the window, it is general enough to include Bogler's input estimation method. Simulation results show, however, that we can obtain a good performance even when the filter considering just one input transition in the window is used. (author). 9 refs., 3 figs., 1 tab.

• Journal of Electrical Engineering and Technology
• /
• v.2 no.2
• /
• pp.188-193
• /
• 2007

Magnetic contactors (MCs) are widely used in industrial equipment such as elevators, cranes and factory control rooms in order to close and open the control circuits. The reliability of MCs mainly depend on mechanical durability and international standards such as IEC 60947-4-1, which stipulates the testing method for MCs. Testing time, however, is so long in usual cases that a method of reducing testing time is required. Therefore, a temperature and voltage-accelerated life testing (ALT) method has been developed to reduce the testing time in this work. The accelerated life test data are analyzed and acceleration factors (AFs) are provided.

• Journal of Aerospace System Engineering
• /
• v.13 no.5
• /
• pp.9-15
• /
• 2019

In this paper, dynamic analysis of a nonlinear active vibration absorber is conducted with a time delay acceleration feedback to suppress the vibration of a nonlinear single degree of freedom primary system. The primary system consisting of linear and nonlinear cubic springs, mass, and damper is subjected to the multi-harmonic hard excitation with a parametric excitation. It is proposed to reduce the vibration of the primary system and the absorber by using a lead zirconate titanate (PZT) stack actuator in series with a spring in the absorber which configures as an active vibration absorber. The method of multiple scales (MMS) is used to obtain the approximate solution of the system under the internal resonance, subharmonic, superharmonic, and principal parametric resonance conditions simultaneously. Frequency and time responses of the system are investigated considering a delay in the feedback for the various parameters of the absorber configuration and controlling force.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.91-92
• /
• 2023

In this study, the chemical composition of converter slag according to CO₂ nanobubble promotion aging time was examined. The CO₂ nanobubble water immersion time was 0, 12, 24, 36, 48 hours, and then dried and pulverized to perform XRD analysis. As a result, the longer the sample was immersed in CO₂ nanobubble water, the higher the amount of calcite produced, and the change after 36 hours was minimal.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.1
• /
• pp.82-96
• /
• 2024

While analyzing traffic flow, speed, traffic volume, and density are important macroscopic indicators, and acceleration and spacing are the important microscopic indicators. The speed and traffic volume can be collected with the currently installed traffic information collection devices. However, acceleration and spacing data are necessary for safety and autonomous driving but cannot be collected using the current traffic information collection devices. 'You Look Only Once'(YOLO), an object recognition technique, has excellent accuracy and real-time performance and is used in various fields, including the transportation field. In this study, to measure acceleration and spacing using YOLO, we developed a model that measures acceleration and spacing through changes in vehicle speed at each interval and the differences in the travel time between vehicles by setting the measurement intervals closely. It was confirmed that the range of acceleration and spacing is different depending on the traffic characteristics of each point, and a comparative analysis was performed according to the reference distance and screen angle to secure the measurement rate. The measurement interval was 20m, and the closer the angle was to a right angle, the higher the measurement rate. These results will contribute to the analysis of safety by intersection and the domestic vehicle behavior model.