• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.5
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• pp.345-351
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• 2018

A distributed control method is proposed to improve the power sharing performance of bidirectional distributed generators and the voltage regulation performance of a DC bus in a DC microgrid. Voltage sensitivity analysis based on power flow analysis is conducted to analyze the structural characteristics of a DC microgrid. A distributed control method using a voltage sensitivity matrix is proposed on the basis of this analysis. The proposed method uses information received through the communication system and performs the droop gain variation method and voltage shift method without additional PI controllers. This approach achieves improved power sharing and voltage regulation performance without output transient states. The proposed method is implemented through a laboratory-scaled experimental system consisting of two bidirectional distributed generators, namely, a load and a non-dispatchable distributed generator in a four-bus ring-type model. The experimental results show improved power sharing accuracy and voltage regulation performance.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.620-630
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• 2018

In this paper, a positioning method of distributed power system is proposed to minimize the average voltage variation of a DC microgrid through voltage sensitivity analysis. The voltage sensitivity under a droop control depends on the position of the distributed power system. In order to acquire a precise voltage sensitivity under a droop control, we analyzed the power flow by introducing a droop bus with the considerations of the droop characteristics. The results of the positioning method are verified through PSCAD/EMTDC simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.828-833
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• 2014

Grid connected transformerless solar power generation system is frequently used with the benefits of cost and efficiency. However, significant DC leakage current can flow from the DC line into the ground with dielectric breakdown in the transformerless solar power generation system. The leakage current occurred in the DC line causes accidents such as fire and electric shock on human. To resolve this problem, high sensitivity DC leakage current sensor is needed. But recently the studies on safety of DC line are not performed. In this paper, a high sensitivity DC leakage current sensor that can detect DC leakage current in solar power generation system, is proposed. Based on the studies, DC leakage current sensor is fabricated and characteristic tests are carried out. Finally, the accuracy of sensor performance is verified by leakage current experiments in solar power generation system.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.1
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• pp.1-8
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• 2011

The accuracy of MR sensor-based electronic compass is influenced by the temperature drift and DC offset of the MR sensor and the OP-amp, the magnetic distortion of nearby magnetic materials, and the compass tilt We design the 3-axis MR sensor and accelerometers-based electronic compass which is compensated by the set/reset pulse switching method on the temperature drift and DC offset, by the execution of hard-iron calibration routine on the magnetic distortion, and by the execution of the Euler rotational equation on the compass tilt. We qualitatively analyze the measured azimuth error on the execution of sensitivity calibration routine which is the normalization process on the different sensitivity of each MR sensor and the different gain of each op-amps. This compensation and analytic result make us design the one degree accuracy electronic compass.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.812-819
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• 2014

The proposed technical work attempts to compare the two key technologies of power distribution, i.e. direct current (DC) and alternating current (AC) in a fiscal manner. The DC versus AC debate has been around since the earliest days of electric power. Here, at least four types of a low voltage DC (LVDC) distribution are examined as an alternative to the existing medium voltage AC (MVAC) distribution with an economic assessment technique for a project investment. Besides, the sensitivity analysis will be incorporated in the overall economic analysis model to cover uncertainties of the input data. A detailed feasibility study indicates that many of the common benefits claimed for an LVDC distribution will continue to grow more profoundly as it is foreseen to arise with the increased integration of renewable energy sources and the proliferation of energy storage associated with the enhanced utilization of uninterruptible power supply (UPS) systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.577-580
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• 2005

This paper reports the high sensitivity actuator for flexible disk. The air stabilized flexible optical disk has very small axial runout. Therefore, It is proper to develop an actuator which has high sensitivity in tracking direction rather than in focusing direction. In order to maximize driving force in radial direction, we present an efficient design of magnetic circuit with simple multi-polarized magnets and auxiliary magnets. Designed magnetic circuit has big force in tracking direction. And we shift 2$^{nd}$ resonance frequency of moving parts Into high frequency band, not causing increase of mass and discord between force and mass centers to secure high sensitivities and sufficient control bandwidth. Finally, experimental results show that designed actuator has superior sensitivity in tracking direction.

• Journal of the Korean Magnetics Society
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• v.23 no.3
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• pp.94-97
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• 2013

Orthogonal fluxgate sensor was fabricated with cylinder-shaped NiZn ferrite core, Cu wire through the core and pickup coil wound on the core, and the bias current effect on the output sensitivity of it was investigated. The output ($$\sim_\sim$$ sensitivity) of the sensor was largely dependent on the operation frequency, and the tendency of sensor output was similar to that of the impedance of pickup coil. The maximum output was obtained by adding the DC bias current of which value was over 50% of the excitation current. The output was saturated when the DC bias current was larger than 50% of the excitation current.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.241-250
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• 2022

This paper describes the design of H-infinity controller for robust control of a DC motor system. The suggested controller can ensure robustness against disturbance and model uncertainty by minimizing H-infinity norm of the transfer function from exogenous input to performance output and applying the small gain theorem. In particular, the controller was designed to reduce the effects of disturbance and model uncertainty simultaneously by formalizing these problems as a mixed sensitivity problem. The validity of the proposed controller was demonstrated by computer simulations and real experiments. Moreover, the effectiveness of the proposed controller was confirmed by comparing its performance with PI controller, which was tested under the same experimental condition as the H-infinity controller.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.163-168
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• 2023

In this paper, a novel platform for chemical sensing and biosensing is presented. The working principle is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multimode interference coupler (MMIC). It has been realized using planar technology to allow integration on a silicon substrate. Firstly, the dispersion curves of DC and MMIC is described, and the design specification of an optimized slot optical waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the refractive index change of sensing analyte is numerically simulated. The numerical results reveal that high effective index change per refractive index unit (RIU) change of analyte is obtained, and the sensitivity can be tuned using the DC and MMIC design technique.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.573-578
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• 2004

EED consists of bridgewire, explosive charge, lead pins and metal case. If a firing signal is injected to EED， the explosive charge in EED is initiated by heating of bridgewire. Electromagnetic waves radiated from high power transmitters or radars can also cause unexpected firing of EED. Therefore, EMC design and test requirements for EED in military specifications are established and applied. This report describes the characteristics of RF sensitivity fur a firing fuse which is used fur EMC test instead of a real EED installed in aircraft. RF firing level of the fuse was predicted using transmission line(TL) theory. n sensitivity and RF sensitivity specified in military specifications were measured.