No abstract

Synthesized GDP shows strong antimicrobial activity against P. acnes in vitro. The clinical improvement observed suggests a topical formulation containing the GDP has therapeutic potential for the improvement of inflammatory-type acne vulgaris by its antimicrobial activity.

This paper proposes a junction temperature estimation algorithm for the insulated gate bipolar transistor (IGBT) based on a power loss calculation and a thermal impedance model for inverter systems. The Simulink model was designed to calculate the power losses of power semiconductor devices and to estimate the junction temperature with a simplified thermal impedance model. This model can estimate the junction temperature up to the transient state, including the steady state. The parameters used to calculate the power losses, the thermal resistance, and the thermal capacitance were optimized for a given inverter to be tested for improving the accuracy. The simulation results and experimental measurement data were compared to verify the proposed junction temperature estimation algorithm. Finally, the algorithm was installed on the inverter controller, and the performance was verified by comparing the real time estimation result with the measured temperature.

No abstract

To detect the three-phase current in the complex plane of a DC link shunt inverter, an algorithm for restoring the current is required. In this paper, a method of dividing the detection voltage and the compensation voltage to match the output voltage as much as possible to reduce the total harmonic distortion while restoring the current is proposed. In addition, an overmodulation algorithm for a 12-step output, which corresponds to the largest voltage in a DC link shunt inverter, is proposed, and a current recovery method in the overmodulation region is proposed. To determine how to ensure a linear output voltage, the fundamental frequency of the output voltage is analyzed through a Fourier series, and a new voltage vector whose fundamental frequency amplitude is equal to the amplitude of the command voltage is calculated. Finally, the performance of the proposed algorithm is verified through simulation and experimentation. The output of a motor was increased by using overmodulation, and the harmonics of the current based on the output voltage were analyzed through a Fourier series.

This paper proposes a resolver offset calibration algorithm that can detect offset with high precision just by configuring a very simple experimental environment. This use of a simple experimental environment holds a great advantage for large-capacity permanent magnet synchronous motors (PMSMs) that require substantial resources to configure an experimental environment, such as EV traction motors. The proposed algorithm is designed based on the PMSM voltage equation. The algorithm is first verified for its validity through simulation with Simulink. Subsequently, it is implemented based on the C-language and installed on an inverter for verification experiments. The implemented algorithm is very simple and requires little execution time and memory. The error in the calibrated offset is experimentally found to converge within 3bits based on 12-bits (the resolution of the commonly used RDC), and the results have very little deviation.

In this paper, we investigate whether there exists market inefficiency in the distribution channel of pork by estimating a developed partial adjustment model that captures the asymmetric price transmission from wholesale to retail prices. The estimation results show that market efficiency exists for the wholesale and two types of retail markets in the distributional channel of pork in Korea. The government's regulation on Sunday sales by hypermarkets plays a significant role in increasing market efficiency, forcing more competition among hypermarkets, and changing the structure of asymmetric price transmission from wholesale to traditional market prices. The results suggest that the policy goal has been achieved in the traditional market by leading to a more efficient price forming due to a lessened degree of asymmetric price transmission from the wholesale price. Although market inefficiency has been maintained in the distribution channel between wholesale market and hypermarket, the behavior of price setting by hypermarkets has not been influenced by the policy.

In this study, a low-voltage three-phase inverter was used alongside a shunt resistor to measure the current. However, it is known that this type of inverter and shunt resistor system has a region where the measurement of current is impossible due to structural limitations. As a result, many studies have focused on this region through the use of additional algorithms. Most studies measured current by forcibly adjusting the PWM duty in order to measure the current at the region where it could not be sensed. However, unfortunately, the total harmonic distortion (THD) increases in the current due to PWM adjustment. This causes an increase in torque ripple and inverter control instability. Therefore, in this paper, current was measured using the Rds(on) value between the drain source resistor when MOSFET was turned on and the Kalman filter in a low-voltage three-phase inverter with a single shunt. Additionally, the value was verified via comparison with the values achieved when a Hall-type current sensor and single shunt were used. As a result, this study confirmed that the inverter with a single shunt performs the same as a Hall-type sensor at the region where current cannot be detected.