• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.4
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• pp.256-264
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• 2018

This paper proposes a three-bridge LLC resonant converter with auxiliary switches for a wide output voltage control range. This converter can be controlled in two ways to achieve a wide controllable output voltage control range of $V_o$ to $3V_o$. The first control mechanism is achieved through the pulse width modulation (PM) of the auxiliary switches and primary switching devices, while the second control mechanism is achieved through the frequency modulation (FM) of the primary switching devices that are configured to operate in the full-bridge switching mode when the auxiliary switches are turned off. The feasibility of using the proposed converter is verified by the results of an experiment with a 2kW prototype.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1303-1314
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• 2018

To match the dynamic lower voltage of a fuel cell stack and the required constant higher voltage (400V) of a DC bus, an H-type structural Boost three-level DC-DC converter with a wide voltage-gain range (HS-BTL) is presented in this paper. When compared with the traditional flying-capacitor Boost three-level DC-DC converter, the proposed converter can obtain a higher voltage-gain and does not require a complicate control for the flying-capacitor voltage balance. Moreover, the proposed converter, which can draw a continuous and low-rippled current from an input source, has the advantages of a wide voltage-gain range and low voltage stress for power semiconductors. The operating principle, parameters design and a comparison with other converters are presented and analyzed. Experimental results are also given to verify the aforementioned characteristics and theoretical analysis. The proposed converter is suitable for application of fuel cell systems.

• Journal of Power Electronics
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• v.18 no.2
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• pp.343-355
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• 2018

A wide-voltage-conversion range bidirectional DC-DC converter is proposed in this paper. The topology is comprised of one typical LC energy storage component and a special common grounded asymmetric H-bridge with four active power switches/anti-parallel diodes. The narrow output PWM voltage is generated from the voltage difference between two normal (wider) output PWM voltages from the asymmetric H-bridge with duty cycles close to 0.5. The equivalent switching frequency of the output PWM voltage is double the actual switching frequency, and a wide step-down/step-up ratio range is achieved. A 300W prototype has been constructed to validate the feasibility and effectiveness of the proposed bidirectional converter between the variable low voltage side (24V~48V) and the constant high voltage side (200V). The slave active power switches allow ZVS turn-on and turn-off without requiring any extra hardware. The maximum conversion efficiency is 94.7% in the step-down mode and 93.5% in the step-up mode. Therefore, the proposed bidirectional topology with a common ground is suitable for energy storage systems such as renewable power generation systems and electric vehicles with a hybrid energy source.

• Journal of the Korean Society of Costume
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• v.57 no.5 s.114
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• pp.183-195
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• 2007

The purpose of the study was to investigate the harmony range and the disharmony range by evaluating the degrees of harmony in terms of types of coloration in men's shirts and neckties. In addition, the study aimed to examine perceptional differences between male and female towards degrees of harmony affected by types of coloration; tone on tone coloration(64), tone in tone coloration(96), contrast coloration(128), achromatic-chromatic coloration(96), and achromatic-achromatic coloration(16). The 4,032 male and 4,032 female college students, were participated in this study. The results are as follows. For five types of coloration, the harmony range and disharmony range were identified. Tone on tone and achromatic-chromatic coloration had a more wide range than tone in tone and contrast coloration from both male and female students. The male students had a more wide range of harmony on all coloration.

• Journal of Ocean Engineering and Technology
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• v.36 no.1
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• pp.50-60
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• 2022

The deep ocean engineering basin (DOEB) of the Korea Research Institute of Ship and Ocean Engineering (KRISO) is equipped with an extreme-environment reproduction facility that can analyze the motion characteristics of offshore structures and ships. In recent years, there have been requirements for a wide range of six-degree-of-freedom (6-DOF) motion measurements for performing maneuvering tests and free-running tests of target objects (offshore structures or ships). This study introduces the process of developing a wide-area motion measurement technology by incorporating the auto-tracking technology of the towing carriage system to overcome the existing 6-DOF motion measurement limitation. To realize a wide range of motion measurements, the automatic tracking control system of the towing carriage in the DOEB was designed as a speed control method. To verify the control performance, the characteristics of the towing carriage according to the variation in control gain were analyzed. Finally, a wide range of motions was tested using a model test object (a remotely operated vehicle (ROV)), and the wide-area motion measurement technology was implemented using an automatic tracking control system for a towing carriage.

• Journal of Power Electronics
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• v.18 no.2
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• pp.640-650
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• 2018

A TRIAC dimmable LED driver with a wide tuning range and a two-stage uniform dimming scheme is proposed in this paper. To solve the restricted dimming range problem caused by the limited conduction ratio of TRIAC dimmers, a conduction ratio compensation technique is introduced, which can increase the output current up to the rated output current when the TRIAC dimmer turns to the maximum conduction ratio. For further optimization, a two-stage uniform dimming diagram with a rapid dimming curve and a slow dimming curve is designed to make the LED driver regulated visually uniform in the whole adjustable range of the TRIAC dimmer. The proposed control chip is fabricated in a TSMC $0.35{\mu}m$ 5V/650V CMOS/LDMOS process, and verified on a 21V/500mA circuit prototype. The test results show that, in the 90V/60Hz~132V/60Hz ac input range, the voltage linear regulation is 2.6%, the power factor is 99.5% and the efficiency is 83%. Moreover, in the dimming mode, the dimming rate is less than 1% when the maximum dimming current is 516mA and the minimum dimming current is only about 5mA.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.465-468
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• 1988

A n-well CMOS Operational Transconductance Amplifier -C(OTA-C) integrator with a wide linear input range is designed. The circuit designed has superior linearity of input voltage range compared with the conventional source-coupled pair OTA. The OTA developed in this paper is versatile in application: diverse applications are in the fields of linear amplifiers, continuous-time filters, gain control circuits, and analog multipliers, etc..

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.225-232
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• 2014

In this study, a cooperative UAV and UGV platform is proposed to obtain a wide range of visual information. The UAV recognizes a pattern marker on UGV and tracks the UGV without user control. It can provide wide range of visual information for a user in the UGV. The UGV by a user is controled equipped with an aluminum board. And the UAV can take off and land on the UGV. The UAV uses two cameras; one camera is used to recognize a pattern marker and another is used to provide a wide range of visual information to the UGV's user. It is guaranteed that the proposed visual-based approach detects and tracks the target marker on the UGV, and then lands well. The experimental results show that the proposed approach can effectively construct a cooperative UAV/UGV platform for obtaining a wide range of vision information.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.777-788
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• 2014

This paper presents a wide output range, high power efficiency reconfigurable charge pump for driving touch panels with the high resistances. The charge pump is composed of 4-stages and its configuration automatically changes based on the required output voltage level. In order to keep the power efficiency over the wide output voltage range, internal blocks are automatically activated or deactivated by the clock driver in the reconfigurable charge pump minimizing the switching power loss due to the On and Off operations of MOSFET. In addition, the leakage current paths in each mode are blocked to compensate for the variation of power efficiency with respect to the wide output voltage range. This chip is fabricated using $0.18{\mu}m$ BCD process with high power MOSFET options, and the die area is $1870{\mu}m{\times}1430{\mu}m$. The power consumption of the charge pump itself is 79.13 mW when the output power is 415.45 mW at the high voltage mode, while it is 20.097 mW when the output power is 89.903 mW at the low voltage mode. The measured maximum power efficiency is 84.01 %, when the output voltage is from 7.43 V to 12.23 V.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.1
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• pp.88-95
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• 2015

For the frequency-domain spectral fatigue analysis, the probability density function of stress range needs to be estimated based on the stress spectrum only, which is a frequency domain representation of the response. The probability distribution of the stress range of the narrow-band spectrum is known to follow the Rayleigh distribution, however the PDF of wide-band spectrum is difficult to define with clarity due to the complicated fluctuation pattern of spectrum. In this paper, efforts have been made to figure out the links between the probability density function of stress range to the structural response of wide-band Gaussian random process. An artificial neural network scheme, known as one of the most powerful system identification methods, was used to identify the multivariate functional relationship between the idealized wide-band spectrums and resulting probability density functions. To achieve this, the spectrums were idealized as a superposition of two triangles with arbitrary location, height and width, targeting to comprise wide-band spectrum, and the probability density functions were represented by the linear combination of equally spaced Gaussian basis functions. To train the network under supervision, varieties of different wide-band spectrums were assumed and the converged probability density function of the stress range was derived using the rainflow counting method and all these data sets were fed into the three layer perceptron model. This nonlinear least square problem was solved using Levenberg-Marquardt algorithm with regularization term included. It was proven that the network trained using the given data set could reproduce the probability density function of arbitrary wide-band spectrum of two triangles with great success.