• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.361-363
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• 2003

The purpose of this research was to discuss the system that operated Ultra sonic transducer of Pelzo electric ceramics type. The structure of controller was made up of digital signal part drive and feedback circuit, and half bridge inverter. Digital signal part was designed to gain the stable oscillation frequency by making consideration of pointed resonance bandwidth. We tried to control inverter by forward feedback condition because BLT based on the flexibility of elements such as temperature and load condition. In addition, transducer was operated as inverter in order to enhance its power efficiency. In this experiment, output voltage waveform and current waveform have been observed by using BLT.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.30-35
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• 1999

Since LPG has a higher octane number and a lower maximum combustion temperature than gasoline it is getting more popular for reducing emissions from the vehicle This paper when an LPG engine works in the range of idle analyzed the operating range preciously an provides reducing method of emissions for the LPG engine. An electronic control unit(ECU) for the LPG engine using a feedback mixer is presented. The ECU is built by using a microcontroller MC68HC05. A PI-controller is imple-mented in the ECU in order to handle to handle Air/Fuel ration control. The experimental results exhibit that the required engine performance are satisfied at idle.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.126-128
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• 2018

Solar array simulator (SAS) is a special DC power supply that regulates the output voltage or current to emulate characteristics of photovoltaic (PV) panels. Especially, the control of SAS is a challenging task due to the nonlinearity in the output curve, which is dependent on irradiance as well as temperature and is determined by panel materials. Conventionally, both current-mode control and voltage-mode control should be alternated by partitioning the operating curve into multiple sections, which is not only for the measurement noise problem with the feedback sensing but also for the control stability issue near the maximum power point. However, the occurrence of transition among different controllers may deteriorate the overall performance. To eliminate the mode transitions, a novel single controller scheme has been introduced in this paper, where the reference operating projection technique enables simple, smooth and numerically stable control. Theoretical consideration on the loop stability issue is discussed and the performance is verified experimentally for the emulation of a PV panel data in view of stability and response speed.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1994.11a
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• pp.146-149
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• 1994

A nonlinear dynamic optimization has been performed for reactor power control system of CANDU 6 nuclear power plant considering xenon, fuel and moderator temperature feedback effects. Integral-of-Time-multiplied Absolute-Error (ITAE) criterion has been used as a performance index of the system behavior. Optimum controller gain are found by searching algorithm of Sequential Quadratic Programming (SQP). System models are referenced from most recent literatures. Signal flow network construction and optimization have been done by using commercial computer software package.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.464-478
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• 1998

In teleoperation, it is important for an operator to feel as if he really were in a distant place. To realize this objective, the various information from a remote site must be presented to the operator. Even though tactile information is very important to efficiently execute a task, it is not yet sufficiently provided for the operator. In this paper, we propose the new mechanism that can provide the more dexterous tactile information to the operator This device utilizing the electromagnetic force is designed to be compact and light enough to be attached to the fingerpad, and designed to be controlled continuously. The magnetic circuit is derived by the probable flux paths method in order to take forces at any given dimension. An optimization technique is also proposed to maximize the tactile force that humans can perceive under the same conditions. The objective function is formulated as maximizing displacements indented on the fingerpad, considering the mechanism of human tactile perception. The optimization formulation is subject to the geometric and rising temperature constraints in the coil. It is demonstrated that, by optimization, the tactile force increases by 24%, compared with that obtained from the initial design.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.282-285
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• 1996

In the water purification plant, the raw water is promptly purified by injecting chemicals. The amount of chemicals is directly related to water quality such as turbidity, temperature, pH and alkalinity. At present, however, the process of chemical reaction to the turbidity has not been clarified as yet. Since the process of coagulant dosage has no feedback signal, the amount of chemical can not be calculated from water quality data which were sensed from the plant. Accordingly, it has to be judged and determined by Jar-Test data which were made by skilled operators. In this paper, it is concerned to model and control the coagulant dosing process using jar-test results in order to predict optimum dosage of coagulant, PAC(Polymerized Aluminium Chloride). The considering relations to the reaction of coagulation and flocculation, the five independent variables(turbidity, temperature, pH, Alkalinity of the raw water, PAC feed rate) are selected out and they are put into calculation to develope a neural network model and a fuzzy model for coagulant dosing process in water purification system. These model are utilized to predict optimum coagulant dosage which can minimize the water turbidity in flocculator. The efficacy of the proposed control schemes was examined by the field test.

• Composites Research
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• v.17 no.4
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• pp.18-24
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• 2004

In this paper, active shape control of composite structures actuated by shape memory alloy (SMA) wires is presented. The thermo-mechanical behaviors of SMA wires were experimentally measured. Hybrid composite structures were established by attaching SMA actuators on the surfaces of graphite/epoxy composite beams using bolt-joint connectors. SMA actuators were activated by phase transformation, which induced by temperature rising over austenite finish temperature. In this paper, electrical resistive heating was applied to the hybrid composite structures to activate the SMA actuators. For (aster and more accurate shape/deflection control of the hybrid composite structure, PID feedback controller was designed from numerical simulations and experimentally applied to the SMA actuators.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.538-545
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• 1995

The heat transfer model of ondol heating system is derived in the linear form. The step responses of On-Off controller, PID controller and Position type fuzzy controllers are compared in the sense of several aspects : variation of temperature feedback variable, variation of supplied heat quantity by the boiler, variation of flow rate, variation of thickness of the base, variation of the outdoor temperature.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.8
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• pp.54-61
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• 2001

A fully on-chip open-drain CMOS output driver was designed for high bandwidth DRAMs, such that its output voltage swing was insensitive to the variations of temperature and supply voltage. An auto refresh signal was used to update the contents of the current control register, which determined the transistors to be turned-on among the six binary-weighted transistors of an output driver. Because the auto refresh signal is available in DRAM chips, the output driver of this work does not require any external signals to update the current control register. During the time interval while the update is in progress, a negative feedback loop is formed to maintain the low level output voltage ($V_OL$) to be equal to the reference voltage ($V_{OL.ref}$) which is generated by a low-voltage bandgap reference circuit. Test results showed the successful operation at the data rate up to 1Gb/s. The worst-case variations of $V_{OL.ref}$ and $V_OL$ of the proposed output driver were measured to be 2.5% and 7.5% respectively within a temperature range of $20^{\circ}C$ to $90^{\circ}C$ and a supply voltage range of 2.25V to 2.75V, while the worst-case variation of $V_OL$ of the conventional output driver was measured to be 24% at the same temperature and supply voltage ranges.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.53-55
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• 2007

This paper describes an implementation of a wide-range dimming controller of a LED backlight for Avionics applications such as the control data unit(CDU) and multi-function display(MFD). A feedback controller using a light sensor is proposed to control the brightness in the low dimming range. The proposed controller provides an improved control performance in the wide dimming range of 1:3000 even under the temperature variations. The experimental results are provided to show the effectiveness of the proposed control system.