• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.551-557
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• 2006

The electrical frequency synchronized periodic torque ripple exits in the AC motor. There are various sources of torque ripple in AC motor such as current measurement error, dead time, etc. This paper proposes a compensation algorithm which suppresses undesired side effect known as the periodic torque ripple of AC motor. The torque ripple compensation classified as the speed ripple detector and torque ripple compensator. This paper proves a speed ripple minimization at steady state by analysis of torque ripple compensator. A new speed ripple detector improves the performance of torque ripple compensation algorithm. The simulation and experimental results show that the compensation algorithm is effective and the torque ripple compensation method improves the performance of speed ripple detector by eliminating torque ripples effectively.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.559-562
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• 2003

In this paper, we introduce a new method detecting thyristor faults of the power converter module in Control Rod Control System. When we control the currents in each coil of Control Rod Drive Mechanism by using the current control method, the current value can follow the current reference despite the faults like the missing phase or the diode acting. Comparing the fault current values with the normal current values, the bad transient characteristics of the abnormal current can make the operations of control rods incorrect. In this case, the information from the current trends cannot be enough to detect the fault occurrence in thyristors. Instead of the coil currents, the state of thyristors can be watched by measuring the coil voltages. In the existing system of Westinghouse type, the ripple detector takes charge of this task. But this detector has some shortcomings in the point of time for fault detection, we come to devise a new fault detection method solving the problems which belong to the ripple detector.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.1
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• pp.22-28
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• 2009

This paper presents a fast received signal strength indicator (RSSI) circuit for wireless communication application. The proposed circuit is developed using power detectors and an analog-to-digital converter to achieve a fast settling time. The power detector is consisted of a novel logarithmic variable gain amplifier (VGA), a peak detector, and a comparator in a closed loop. The VGA achieved a wide logarithmic gain range in a closed loop form for stable operation. For the peak detector, a fast settling time and small ripple are obtained using the orthogonal characteristics of quadrature signals. In $0.18-{\mu}m$ CMOS process, the RSSI value settles down in $20{\mu}s$ with power consumption of 20 mW, and the maximum ripple of the RSSI is 30 mV. The proposed RSSI circuit is fabricated with a personal handy-phone system transceiver. The active area is $0.8{\times}0.2\;mm^2$.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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• pp.453-456
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• 2016

The major causes of electrical fire in low-voltage distribution lines are classified into short-circuit fault, overload fault, electric leakage, and electric contact failure. The special principal factor of the fire is electric arc or spark accompanied with such electric faults. This paper studies the development of an electric fire prevention system with detection and alarm of that in case of parallel arc fault occurrence in low-voltage distribution lines. The proposed system is designed on algorithm sensing the instantaneous voltage drop of line voltage at arc fault occurrence. The proposed detector has characteristics of high-speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. A new sensing control method that shows the detection of parallel arc fault is sensed to ripple voltage drop through a diode bridge full-wave rectifier at electrical accident occurrence. Some experimental tests of the proposed system also confirm the practicality and validity of the analytical results.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.454-459
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• 1997

The good features of a switched reluctance motor(SRM) are appreciated by the appliance manufactures. And it is spread into a commercial and industries market. The few disadvantage of the motor is higher torque ripple and noise. This paper proposes an instantaneous torque control scheme to control a speed precisely. It adapts phase-locked loop (PLL) technique to control speed precisely. In this control scheme, the phase detector signal of the PLL regulates the switching dwell angle flexibly and the loop filter's signal controls adaptively the instantaneous switching voltage. Experimental results show that drive performance is good with low torque ripple.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.48-57
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• 2020

MCU used in applications such as wireless chargers and USB type-C require MTP memory with a small cell size and a small additional process mask. Conventional double poly EEPROM cells are small in size, but additional processing masks of about 3 to 5 sheets are required, and FN tunneling type single poly EEPROM cells have a large cell size. In this paper, a 110nm MTP cell using a vertical PIP capacitor is proposed. The erase operation of the proposed MTP cell uses FN tunneling between FG and EG, and the program operation uses CHEI injection method, which reduces the MTP cell size to 1.09㎛2 by sharing the PW of the MTP cell array. Meanwhile, MTP memory IP required for applications such as USB type-C needs to operate over a wide voltage range of 2.5V to 5.5V. However, the pumping current of the VPP charge pump is the lowest when the VCC voltage is the minimum 2.5V, while the ripple voltage is large when the VCC voltage is 5.5V. Therefore, in this paper, the VPP ripple voltage is reduced to within 0.19V through SPICE simulation because the pumping current is suppressed to 474.6㎂ even when VCC is increased by controlling the number of charge pumps turned on by using the VCC detector circuit.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.3
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• pp.164-172
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• 2004

This paper presents the comparison results of some kinds of control method in circumstance of eccentric load. The plant to be controlled is a computed tomography(CT) driven by a permanent magnet synchronous motor. In a CT system, many units are attached on the rotationally part of a gantry such as x-ray tube, detector, heat exchanger, and data acquisition unit etc. Therefore keeping many components to balance which have different weight is not easy; this is inescapable problem in the all CT systems. To solve this problem against eccentric load, some kinds of control method have been compared and analysed by using protype CT. From the experimental results it is vilified that the CT drive system with model reference control method indicates higher speed regulation ability regardless of variable eccentric weight and uncertain position, and also in the limit condition of constant eccentric weight and fixed position, the compensation method with sinusoidal form is a strong candidate in view of speed ripple reduction.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1147-1154
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• 2022

Now that the development of autonomous driving is progressing, LiDAR has become an indispensable element. However, LiDAR is a device that uses lasers, and laser side effects may occur. One of them is the much-talked-about eye-safety, and developers have been satisfying this through laser characteristics and operation methods. But eye-safety is just one of the problems lasers pose. For example, irradiating a laser with a specific energy level or higher in a dusty environment can cause deterioration of the dust particles, leading to a sudden explosion. For this reason, the dust ignition proof regulations clearly state that "a source with a pulse period of less than 5 seconds is considered a continuous light source, and the average energy does not exceed 5 mJ/mm 2 or 35 mW" [2]. Energy of output optical power is limited by the law. In this way, the manufacturer cannot define the usage environment of the LiDAR, and the development of a LiDAR that can be used in such an environment can increase the ripple effect in terms of use in application fields using the LiDAR. In this paper, we develop a LiDAR with low optical power that can be used in environments where high power lasers can cause problems, evaluate its performance. Also, we discuss and present one of the directions for the development of LiDAR with laser power limited by dust ignition proof regulations.