• Journal of Power System Engineering
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• v.19 no.4
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• pp.89-96
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• 2015

This paper investigates some strategies to overcome the chattering problem of the conventional sliding mode observer (SMO) and to improve the rotor position estimation performance for full range sensorless control of a PMSM. An adaptive observer gain based on the Lyapunov's stability criterion and a cascade low pass filter with advanced phase delay compensation were proposed to reduce the chattering problem and to strengthen the filtering capability of the SMO. Several cases studies through experiments were carried out to confirm conventional SMO's problems and effectiveness of the proposed strategies. The experimental results show that the proposed method gives precise estimation on speed and rotor position when the motor rotates on 2% of its rated speed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5347-5360
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• 2016

In decode and forward relay systems, choosing the duplex mode is an important factor to the performance. To satisfy the performance requirement, self-interference must be mitigated for the full-duplex relay (FDR), and the resource efficiency must be increased for the half-duplex ratio (HDR). Therefore, if a wise scheme to consider these two factors exists, decode and forward relay systems are used more effectively. This study proposes a new duplex selection scheme for decode and forward relay systems. The proposed duplex selection scheme chooses the better duplex mode according to the channel statistical conditions with optimal power allocation. The simulation results show that the proposed duplex scheme with optimal power allocation has lower outage probability than the FDR and the HDR.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.4
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• pp.257-262
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• 2008

This paper studies the operational characteristics of Multi-Phase Interleaved Boost converter operating in Boundary Conduction Mode. The generalized transfer functions of interest are derived from the full-order averaged model approach and then the steady-state and dynamic characteristics are analyzed. The theoretical results are verified through an experimental prototype of the 800W boost PFC converter for 60inch PDP power module.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.461-465
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• 1996

Position and rate control modes arc the two common modes for controlling remote manipulators with joysticks or hand controllers. Generally, position mode is easier for teleoperation than rate modes, when the manipulation work space is small or comparable to the human operator's control space. When the telemanipulator's work space is very large, human operator's control motion range must be large to allow telemanipulator's full range of motion resulting poor control resolution. One way to solve the poor resolution problem is to use indexing. However, rate mode can provide any higher degree of resolution without use of indexing. If two modes are mixed, master controller will be more convenient. The mixed mode algorithm, changes operating mode from position mode to rate mode or vise versa using fuzzy logic. The fuzzy logic algorithm, which has been designed to recognize the teleoperator's intended motion properly, provides an intelligence to a master controller.

• Journal of Power Electronics
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• v.18 no.4
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• pp.975-984
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• 2018

This work presents a high efficiency phase shifted full bridge (PSFB) DC-DC converter for use in the second stage of a battery charger for neighborhood electrical vehicle (EV) applications. In the design of the converter, Lithium-ion battery cells are preferred due to their high voltage and current rates, which provide a high power density. This requires wide range output voltage regulation for PSFB converter operation. In addition, the battery charger works with a light load when the battery charge voltage reaches its maximum value. The soft switching of the PSFB converter depends on the dead time optimization and load condition. As a result, the converter has to work with soft switching at a wide range output voltage and under light conditions to reach high efficiency. The operation principles of the PSFB converter for the continuous current mode (CCM) and the discontinuous current mode (DCM) are defined. The performance of the PSFB converter is analyzed in detail based on wide range output voltage and load conditions in terms of high efficiency. In order to validate performance analysis, a prototype is built with 42-54 V / 15 A output values at a 200 kHz switching frequency. The measured maximum efficiency values are obtained as 94.4% and 76.6% at full and at 2% load conditions, respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.464-471
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• 2007

This paper presents a maneuver analysis of a full-vehicle featuring electrorheological(ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.301-303
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• 2001

In this paper we present a Capacitor Charging Power Supply (CCPS) using a series-resonant three-level inverter topology to improve voltage regulation and use semiconductor switches having low blocking voltage capability such as MOSFETs. This inverter can be operated with two modes, Full Power Mode (FPM) and Half Power Mode (HPM). In FPM inverter supplies the high frequency step up transformer with full DC-link voltage and in HPM with half DC-link voltage. HPM switching method will be adopted when CCPS output voltage reaches the preset target value and operates in refresh mode-charge is maintained on the capacitor. In this topology each semiconductor devices blocks a half of the DC-link voltage[2]. A 15kW, 30kV CCPS has been built and will be tested for an electric precipitator application. The CCPS operates from an input voltage of 500VDC and has a variable output voltage between 10 to 30kV and 1kHz repetition rate at 44nF capacitive load [3]. A resonant frequency of 67.9kHz was selected and a voltage regulation of $0.83\%$ has been achieved through the use of half power mode without using the forced cut off the switch current [1]. The theory of operation, circuit topology and test results are given.

• Journal of IKEEE
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• v.11 no.2
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• pp.83-88
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• 2007

This paper proposes an 8${\times}$8 bit parallel multiplier using MOS current-mode logic (MCML) circuit for low power consumption. The 8${\times}$8 multiplier is designed with proposed MCML full adders and conventional full adders. The designed multiplier is achieved to reduce the power consumption by 9.4% and the power-delay-product by 11.7% compared with the conventional circuit. This circuit is designed with Samsung 0.35${\mu}m$ standard CMOS process. The validity and effectiveness are verified through the HSPICE simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.369-375
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• 2009

In this paper, we propose a 2D-3D convertible display system having a background of full-parallax integral images. The proposed system is composed of integral imaging system and conventional 2D flat display and is able to operate either 3D mode or 2D mode. In 3D mode, the 3D image is generated by combining the 2D main image with the background image based on integral imaging. In 2D mode, the integral imaging system plays a role as the back-light of 2D flat display and then 2D image is observed through 2D flat display. To show the usefulness of the proposed system, we carry out the preliminary experiments and present the successful experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1295-1302
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• 2003

In order to evaluate a failure behavior of pipe with notch-type wall thinning, the present study performed full-scale pipe tests using the 102mm, Schedule 80 pipe specimen simulated notch- and circular-type thinning defects. The pipe tests were conducted under the conditions of both monotonic and cyclic bending moment at a constant internal pressure of 10 MPa. From the results. of experiment the failure mode, load carrying capacity, deformation ability, and fatigue life of a notch-type wall thinned pipe were investigated, and they were compared with those of a circular-type wall thinned pipe. The failure mode of notched pipe was similar to that of circular-type thinned pipe under the monotonic bending load. Under the cyclic bending load, however, the mode was clearly distinguished with variation in the shape of wall thinning. The load carrying capacity of a pipe containing notch-type wall thinning was about the same or slightly lower than that of a pipe containing circular-type wall thinning when the thinning area was subjected to tensile stress, whereas it was higher than that of a pipe containing circular-type thinning defect when the thinning area was subjected to compressive stress. On the other hand, the deformation ability and fatigue life of a notch-type wall thinned pipe was lower than those of a circular-type wall thinned pipe.