• KSTLE International Journal
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• v.4 no.2
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• pp.37-42
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• 2003

One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings, which we don't expect for conventional passive bearings. These failure modes include electric power outage, power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults in the system. In this paper, we designed a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults which are the most common faults in a magnetic bearing system. We implemented the existing fault-tolerant algorithms to experimentally prove the adequacy of the algorithms for industrial applications. As it turns out, the system can operate even with three simultaneously failing poles out of eight actuator poles.

• Journal of Drive and Control
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• v.16 no.1
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• pp.22-28
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• 2019

This paper develops ABS braking real - time simulator to develop vehicle braking system by simulation. Recently, real-time simulation is widely used in the development of vehicles to decrease development time. In the field of electronic braking, real-time simulation is actively underway. In order to simulate electronic braking model in real time, a vehicle model, a hydraulic model, and a control S/W model are required. These models must be calculated in one platform. Therefore, in this paper, a vehicle model composed of CarSim and a hydraulic model composed of SimulationX using S/W in actual ABS controller was developed as a Simulink model base and linked with Matlab real time model. Using this real-time model, design effects of the electronic braking controller were simulated according to road surface condition to verify its operability.

• International Journal of Fluid Machinery and Systems
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• v.2 no.1
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• pp.92-101
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• 2009

The purpose of this paper is to gain a greater understanding of the performance of practical wind turbine generating systems with differing output power controllers and controlling means for wind turbine speed. Subjected wind turbines, both equipped with an asynchronous power generator, are located at two sites and are defined as wind turbine A and wind turbine B in this study, respectively. Their performance differences are examined by measuring wind speed and electric parameters. The study suggests that both wind turbines have a clear linkage between current and output power fluctuations. Comparison of the fluctuations to wind speed fluctuation, although they are triggered primarily by wind speed fluctuation, clearly indicates the specific behaviors inherent to the respective turbine control mechanisms.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1521-1523
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• 2005

High voltage plasma power supply was adopted to control polluted gases and an ozone generation. Bidirectional pulse power supply consisted of power semiconductor switch devices, a high voltage transformer, and a control board adapted switching method. Plasma power supply with sinusoidal bidirectional pulse, which has output voltage range of 0-20kV and output frequency range of 1kHz-20kHz, is realized. Using proposed system, pulsed high voltage/high frequency discharges were tested in a DBD(dielectric barrier discharge) reactor, and the spatial distribution of a glow discharge was observed. The system showed stable operational characteristics, even though the voltage and the frequency increased. Above features were verified by experiments.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.3-8
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• 1998

The industrial revolution in England was based on the manufacturing systems by the power of water mill and rapidly progressed by the innovation of steam engine. It is no exaggeration to say that today's civilization is realized by the development of various types of power machinery, namely fluid machinery and heat engine. The electric energy is converted mainly from thermal energy (mainly steam) of mineral oil, coal and nuclear fuel through generator connected with steam turbine which is a kind of power machinery. There are various types of power machinery as shown in Tables 1a and 1b. They are classified into two types by use. One is absorption type of fluid and/or thermal energy, for examples, windmill and heat engine. The other is provision type of the energies for examples, pump, compressor and propulsion. By flow type, they are also classified by two types, turbo type and positive-displacement type. The turbo type began from water mill and windmill and evolve to steam turbine and finally to gas turbine. The positive-displacement type started from reciprocating water pump and developed into steam engine and changed to reciprocating combustion engine. The pumps and motors used in oil hydraulic system for power control are also positive-displacement type.

• Journal of Drive and Control
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• v.19 no.3
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• pp.32-38
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• 2022

The in-wheel drive gearbox for military special vehicles converts the high-speed & low-torque output generated by the electric servomotor, into low-speed & high-torque mechanical power. As the vehicle is remotely maneuvered in mountainous terrain, wet fields, rough terrain, etc., the gearbox must generate a maximum input speed exceeding 5,000 rpm, a maximum torque of 245 Nm, and MTBF of 9,600 km. The purpose of this study was to analyze the failure mode of the gearbox, to ensure the durability of the in-wheel drive gearbox. Also, the field load test data of the vehicle was analyzed, the acceleration durability test standards were established, the acceleration durability test was conducted, and the durability test results were analyzed as well.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.147-152
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• 2003

This study was conducted to analyze the energy balance in closed transplants production system (CTPS) for the production of high quality transplants. Potato (Solanum tuberosum L. cv. Dejima) plug seedlings were grown for 15 days at air temperature of 20$^{\circ}C$, relative humidity of 70%, photoperiod of 16/8 h, and photosynthetic photon flux (PPF) of 200 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ following 5 days of tooting in CTPS. Electric energy consumption was 46% for lighting, 35% for cooling, 16% for heating, 2% for air circulation, and 1% for humidifying. The electric energy utilization efficiency and the short-wave energy utilization efficiency were 0.5% and 5.4%, respectively. These results suggest that CTPS has the feasibility for the commercial production of potato plug seedlings if the electric energy consumption in CTPS is reduced and the electric energy utilization efficiency is increased.

• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.134-142
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• 1990

This study was carried out for the development of greenhouse temperature control system by modifying an APPLE-II microcomputer attached with several interface systems. The interface systems are composed of 12 bit A/D converter, output port, multiplexer, time clock, etc. Under the operation of developed system, the greenhouse temperature was to be manipulated within the setting temperatures assumed to be appropriate for certain plant growth. The temperature control equimpents installed in the greenhouse are one-speed propeller type fan and two-phase electric heater, which are selectively started or stopped according to the control logic programmed in the control system. The results are summarized as follows : 1. The difference between two temperatures measured by the developed system and the self-recording thermometer calibrated with standard thermometer was less than $1^{\circ}C$. 2. When the temperature were measurd by 12 bit A/D converter and both electric heater and ventilation fan were controlled by developed ON/OFF logic, greenhouse temperature showed narrow fluctuation bands of less than $1^{\circ}C$ near the setting temperatures. 3. The temperature acquisition and control system developed in this study is expected to be applicable to environment control system such as greenhouse only by modifying the logic based on long term experimental data. 4. In order to reduce the measurement error and to increase the system control efficiency, it is recommended that continuous study should be carried out in the aspect of eliminating various systematic noises and improving the environmental control logic.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.4
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• pp.27-32
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• 2007

Gears, crucial components in modern precision machinery for power transmission mechanisms, are required to have low contacting noise with high torque transmission, which makes the use of gear-tooth profile modifications and gear-tooth surface crowning extremely efficient and valuable. Due to the shortcomings of current techniques, such as manual rectification, mechanical modification, and numerically controlled rectification, we propose a novel electrochemical gear-tooth profile modification method based on an artificial neural network control technique. The fundamentals of electrochemical tooth-profile modifications based on real-time control and a mathematical model of the process are discussed in detail. Due to the complex and uncertain relationships among the machining parameters of electrochemical tooth-profile modification processes, we used an artificial neural network to determine the required processing electric current as the tooth-profile modification requirements were supplied. The system was implemented and a practical example was used to demonstrate that this technology is feasible and has potential applications in the production of precision machinery.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.475-482
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• 2016

The active control of noise generated by the compressor and transmitted out of the machine room through the windows is implemented based on the FIR filter. The machine room contains most of noise sources of electric home appliances, air-conditioners and refrigerators, for example. To actively reduce the noise from the machinery room. In this paper, the transfer function of the controller for minimization of the acoustic power transmitted through the windows is mathematically formulated. The transfer functions required for implementation of the active controller are the measured. The measurements are conducted in this initial stage under the operation of the compressor with no load. For improvement of the reliability of the transfer function of the compressor to the acoustic power, additional operational measurements are performed. The real time controller is implemented based on the FIR filter using the measured transfer functions and the performance of the active controller is estimated. Control performance is measured about 3 dB ~ 10 dB in reduction of the sound power at the peaks of the compressor noise.