• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.912-913
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• 2008

In this paper, peak detector of generator output voltage and variable gain controller is introduced for the fast dynamic response. The general r.m.s. detecting signal of generator has inherent time delay from the actual signal. So the dynamic response of generator using conventional PID controller has some problem in sudden load change. In order to overcome this problem, the peak detector and signal selector with variable gain controller is used in this paper. The proposed control scheme is verified from experimental test of 200kW diesel engine-generator.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.494-499
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• 2011

One of the devices to prevent separated flow over a wing or a flap at high angle of attack is a vortex generator. In the present work, we numerically study the flow around a low-profile or micro vortex generator whose height is less than local boundary layer thickness which can delay separation with a minimum drag penalty owing to its very small wetted surface area. As a first step toward a parametric study to efficiently design this MVG flow control system, we simulate the flow around a single MVG on a flat plate. For the simulation, we employ OpenFOAM with Launder-Sharma ${\kappa}$-epsilon model. The analysis results are validated by comparing with experimental results of a rectangular MVG at an angle of attack of 10 degrees whose height is 20% of local boundary layer. Important results and aspects of this numerical study are discussed. We also simulate the flow around rectangular, triangular and trapezoidal MVGs and the results are compared

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1195-1199
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• 2008

In this paper, peak detector of generator's output voltage and variable gain controller are introduced for a fast dynamic response. The conventional r,m.s, signal detected has inherent time delay, and the dynamic response of generator using conventional PID controller has some problem in sudden load change. In this paper, the peak detector and signal selector with variable gain controller is used to overcome this problem. The main controller can check the voltage state from the peak detector. When a sudden load change, the over-voltage and under-voltage signal from peak detector change the controller's gain and exciter's current reference. The proposed scheme can improve the dynamic response, which is verified from experimental test of 200kW diesel engine-generator.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.139-143
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• 2003

Study on the ignition characteristics of combustor and gas generator for LOx-kerosene liquid rocket engine was performed experimentally through a series of combustion tests of sub-scale engine combustor and gas generator. Characteristic of gas-torch ignitor based on gaseous methane and gaseous oxygen was compared with hypergolic ignition using propellant tri-ethyl-aluminium. Gas-torch ignitor showed good performance on igniting sub-scale liquid rocket engine combustor and gas generator. It was observed that the ignition delay is also affected by the extent of nitrogen in the combustion chamber.

• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.125-134
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• 2009

This paper presents details on a tube inspection robotic system and a positioning method of the robot for a steam generator (SG) in nuclear power plants (NPPs). The robotic system is separated into three parts for easy handling, which reduces the radiation exposure during installation. The system has a supporting leg to increase the rigidity of the robot base. Since there are several thousands of tubes to be inspected inside a SG, it is very important to position the tool of the robot at the right tubes even if the robot base is positioned inaccurately during the installation. In order to obtain absolute accuracy of a position, the robot kinematics was mathematically modeled with the modified DH(Denavit-Hartenberg) model and calibrated on site using tube holes as calibration points. To tune the PID gains of a commercial motor driver systematically, the time delay control (TDC) based gain tuning method was adopted. To verify the performance of the robotic system, experiments on a Framatomes 51B Model type SG mockup were undertaken.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.67-73
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• 2015

This paper presents a fully integrated 3 - 5 GHz IR-UWB(impulse radio ultra-wide band) RFIC for Location based system. The receiver architecture adopts the energy detection method and for high speed sampling, the equivalent time sampling technique using the integrated DLL(delay locked loop) and 4 bit ADC. The digitally synthesized UWB impulse generator with low power consumption is also designed. The designed IR-UWB RFIC is implemented on $0.18{\mu}m$ CMOS technology. The receiver's sensitivity is -85.7 dBm and the current consumption of receiver and transmitter is 32 mA and 25.5 mA respectively at 1.8 V supply.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1022-1025
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• 2008

This paper presents the generation of the high voltage squarewave pulse using distributed RLC circuit. The demonstrated test was performed with the distributed RLC circuit which consists of the resistance, the inductance and the capacitance. Pspice simulation was also conducted about the experiment circuit. The result of the experiment was in good agreement with the result of the simulation. Theoretical analysis of the initial peak value at the squraewave pulse was derived from the results of the experiment and simulation. Additionally, the characteristics of the time delay was analyzed about the spherical gap switch and the surface discharge gap switch, respectively. It is concluded that the surface discharge gap switch is better than the spherical gap switch to reduce the time delay.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.415-419
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• 1996

This paper presents motor speed and phase angle detection method using a sinusoidal AC tachogenerator. The 2-phase or 3-phase output tacho-generator can be adopted, and its' output voltages must have sinusoidal waveforms. Because the detection algorithm is simple, the proposed method can be implemented with analog devices of microprocessor conveniently. And the proposed method has a very short detection delay time. Especially in the analog implementation, there is no delay time without the settling time of analog devices. With the Experimental results, it is verified that the proposed method can accurately detect the instantaneous motor speed and phase over the wide ranges.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.6
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• pp.963-971
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• 1990

This paper proposes a memory intensive VLSI architecture for the realization of real-time 3x3 neighborhood processor based on the distributed arithmetic. The proposed architecture is characterized by a bit serial and multi-kernel parallel processing which exploits the pixel kernel parallelism and concurrency. The chip implements 8 neighborhood processing elements in parallel with efficirnt input and output modules which operate concurrently. Besides the a4chitectural design of a neighborhood processor, the design methodology using module generator concept has been considered and MOGOT(MOdule Generator Oriented VLSI design Tool) has been constructed based on the workstation. Based on these design environments MOGOT, it has been shown that the main part of the suggested architecture can be designed efficiently using 2\ulcorner double metal CMOS technology. It includes design of input delay and data conversion module, look-up table for inner product operation, carry save accumulator, output data converter and delay module, and control module.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.179-181
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• 1998

In this paper, one chip PWM pattern generator which eliminates time delay of computations and improves utilization factor of voltage is proposed. Both amplitude of sinusoidal signal and triangular signal are directly controlled. Thus, time delay of computations can be eliminated, and it is possible to track accurately instantaneous current for a sudden change of load with microprocessor 80C196KC. In addition, setting dead-time is also possible for wide range. From experimental work with inverter system for driving induction motor, the validity of proposed one chip PWM pattern generator is verified.