• The Transactions of the Korean Institute of Power Electronics
• /
• v.28 no.1
• /
• pp.68-75
• /
• 2023

This paper proposes a three-phase single-stage AC-DC converter for the small wind generation system. Input power factor improvement and insulated output can be implemented with the proposed three-phase single-stage AC-DC converter under the wide power generation voltage (80-260 V_ac) and frequency (10-42 Hz) in a small wind power generation (WPG) system. The proposed converter is also capable of zero-voltage switching in the primary-side switches and zero-current switching in the secondary-side diodes by phase-shift control at a fixed switching frequency. In addition, it is possible to control a wide output voltage (V_o: 39 V_DC-60 V_DC) by varying the link voltage and improving the input power factor (PF) and the total harmonic distortion factor (THD_i). Simulation and experimental results verified the validity of the proposed converter.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.42 no.1
• /
• pp.79-85
• /
• 2005

In this paper, low-power design and implementation techniques for IMT-2000 interpolation filter are proposed. Processor technique for DA(Distributed Arithmetic) filter and minimization technique for number of addition in CSD(Canonic Signed Digit) filter are utilized for low-power implementation. proposed filter structure consists of 3 blocks. In the first CSD coefficient block, every possible 4 bit CSD coefficients are calculated and stored. In second processor block, multiplication is done by MUX and addition processor in terms of filter coefficient. Finally, in third shift register block, multiplied values are output and stored in shift register. For IMT-2000 interpolation filter, proposed and conventional structures are implemented by using Verilog-HDL coding. Gate counts for the proposed structure is reduced to 31.57% comparison with those of the conventional one.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.4
• /
• pp.219-225
• /
• 2014

The New efficient Mux-based scan latch cell design and scan test of LOS/LOC modes are proposed for detection of delay faults in digital logic circuits. The proposed scan cell design can support LOS(Launch-off-Shift) and LOC(Launch-off-Capture) tests with high fault coverage and low scan power and it can alleviate the problem of the slow selector enable signal and hold signal by supporting the logic capable of switching at the operational clock speeds. Also, it efficiently controls the power dissipation of the scan cell design during scan testing. Functional operation and timing simulation waveform for proposed scan hold cell design shows improvement in at-speed test timing in both test modes.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.9 no.3
• /
• pp.239-245
• /
• 2017

As a new technical approach, wave energy converter by using vertical motion of water in the multiple water chambers were developed to realize actual wave power generation as eco-environmental renewable energy. And practical use of wave energy converter was actually to require the following conditions: (1) setting up of the relevant device and its application to wave power generation in case that severe wave loading is avoided; (2) workability in installation and maintenance operations; (3) high energy conversion potential; and (4) low cost. In this system, neither the wall(s) of the chambers nor the energy conversion device(s) are exposed to the impulsive load due to water wave. Also since this system is profitable when set along the jetty or along a long floating body, installation and maintenance are done without difficulty and the cost is reduced. In this paper, we describe the system which consists of a float, a shaft connected with another shaft, a rack and pinion arrangement, a ratchet mechanism, and rotary type generator(s). Then, we present the dynamics model for evaluating the output electric power, and the results of numerical calculation including the effect of the phase shift of up/down motion of the water in the array of water chambers aligned along the direction of wave propagation.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.5
• /
• pp.400-408
• /
• 2007

In this paper, development of the 8kW parallel module converter is presented. For a effective configuration of FB-PWM converter, this paper proposes 4-parallel operation of 2 kw-module. FB converter of 2-kW module is controlled by phase shut PWM and in order to achieve ZVZCS, the simple auxiliary circuit is applied in secondary side. In order to achieve ZCS, control logic for auxiliary circuit operation is designed to reset the primary current during free-wheeling period. For output current sharing of 4-modules, the charge control is employed. The charge control logic is designed with phase shift PWM logic. Voltage controller is implemented by using DSP(TMS320LF2406) with A/D conversion data of the output current and voltage of each module. The developed converter is installed in PCU(Power Conditioning Unit) for HSG(High Speed Generator) in a vehicle and health monitoring system is implemented for vehicle operation test. Finally, performance of the developed converter is proved under practical operation of HSG.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.4C
• /
• pp.362-369
• /
• 2007

APSK (Amplitude Phase Shift Keying) digital modulation is characterized by the circular positioning of the transmission symbols in the constellation diagram. Due to such structural characteristics, the peak-to-average power ratio of the APSK modulation is lower than that of the QAM (Quadrature Amplitude Modulation), and the amount of performance degradation over nonlinear channels can be mitigated. The APSK modulation scheme has recently been adopted as satellite communication system standards including the DVB-S2 (Digital Video Broadcasting - Satellite, Version 2). In this paper, a BER (Bit Error Rate) upper bound approximation formula is derived using the channel model with the output power saturation characteristics, and its accuracy is demonstrated. Using the derived formula, the input power level that minimizes the BER is determined. The optimized performance based on the radii ratio of the 16APSK constellation and the channel saturation level is also presented.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.1
• /
• pp.97-102
• /
• 2016

In this paper, a bidirectional power supply charger is proposed. This system used a solar cell panel to generate electricity and used super capacitors to store these energies, which can be used for the robot cleaner or some other electronic products. This system include a phase-shift controlled bidirectional dual active bridge (DAB) converter, solar panel super capacitors and DSP controller. In the daytime it can charge to the super capacitors to store the energy generated by the solar cell panel and in the night it will release the energy stored in the super capacitors to loads. A prototype of the proposed bidirectional power supply charger system was designed which can achieve 18V to 30V input, 10V/20W output to super capacitors and 9V/6.5W output when it acts as a charger for the robot cleaner. The system is verified to be sTable and reliable by both the simulation and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.3
• /
• pp.20-28
• /
• 2002

This paper describes the time sharing type high frequency resonant inviter can be used as power of induction heating. This closed inverter can be obtained output frequency three times than switching frequency by composing three unit inviter of conventional Half-Bridge serial resonant inverter in parallel with input power source also, this reduce switching loss because it has ZVS function. The analysis of the proposed circuit is generally described by using the normailized proposed parameters. The principle of basic operating and the its charasteristics are extimated by the parameters such as switching frequency($\mu$), the variation of Phase angle($\phi$) of Phase-shift. Experimental results are presented to verify theoretical discussion. This preposed inverter will be able to be prastically used as a power supply in various fields as induction, heating application, DC-DC converter etc.

• Journal of Internet Computing and Services
• /
• v.24 no.2
• /
• pp.57-66
• /
• 2023

Currently, a new energy system is emerging that implements consumption reduction by improving energy efficiency. Accordingly, as smart grids spread, the rate system by timing is expanding. The rate system by timing is a rate system that applies different rates by season/hour to pay according to usage. In this study, external factors such as temperature/day/time/season are considered and the time series prediction model, LSTM, is used to predict energy power usage data. Based on this energy usage prediction model, energy usage charges are reduced by analyzing usage patterns for each device and transferring power energy from the maximum load time to the light load time. In order to analyze the usage pattern for each device, a clustering technique is used to learn and classify the usage pattern of the device by time. In summary, this study predicts usage and usage fees based on the user's power data usage, analyzes usage patterns by device, and provides customized demand transfer services based on analysis, resulting in cost reduction for users.

• Journal of radiological science and technology
• /
• v.35 no.1
• /
• pp.9-15
• /
• 2012

The purpose of this study is to provide preliminary data for bone disease prevention by examining the correlation between bone mineral density, and lifestyle and nutritional status of female shift workers, at general hospitals with an irregular life cycle. The subjects for this study were 232 female shift workers, over 30 years old, who worked at a general hospital more than 5 years. From the subjects, who understood the purpose of this study and decided to be participated, we measured serum albumin, total brotein, total cholesterol, hematocrit, hemoglobin, calcium, phosphorus from blood test, and obtained bone mineral density. To analyze the effectiveness of the variables for explanation power, we established the studied values as independent variables, bone minral density as a dependent variable. Exercise, the number of drinking, calcium, and phosphorus were selected as significant variables and the explanation power was 10.2%. The bone mineral density were significantly higher at the subjects who had exercise, higher calcium and phosphorus possession, and drank alcohol than the opposite cases. Regular exercise, and 1:1 intake of calcium and phosphorous were important to prevent osteoporosis for the subjects who were working three shifts which cause irregular lifestyle.