• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1614-1622
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• 2014

A novel equivalent flux sliding-mode observer (SMO) is proposed for dual three-phase interior permanent magnet synchronous motor (DT-IPMSM) drive system in this paper. The DT-IPMSM has two sets of Y-connected stator three-phase windings spatially shifted by 30 electrical degrees. In this method, the sensorless drive system employs a flux SMO with soft phase-locked loop method for rotor speed and position estimation, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Meanwhile, to get the regulator parameters of current control, the inner current loop is realized using a decoupling and diagonal internal model control algorithm. Experiment results of 2MW-level DT-IPMSM drives system show that the proposed method has good dynamic and static performances.

• The Journal of Korea Robotics Society
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• v.17 no.3
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• pp.308-313
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• 2022

This paper proposes a velocity control method for a permanent magnet synchronous motor (PMSM) based on the Koopman operator that does not require model parameter information except for pole-pair of the motor and external load. First, the Koopman operator is derived using observable functions and observation data. Then, the desired q-axis current corresponding to the desired velocity is generated using the relationship between the continuous-time Koopman operator and the dynamics of PMSM. Also, the dynamic equation of PMSM is expressed as a linear form in observable space using the discrete-time Koopman operator. Finally, it is applied to the linear quadratic regulator (LQR) to derive the final form of control input. To verify the proposed method, the conventional cascade PI controller and the LQR controller configured with the existing technique are compared with the proposed method in the viewpoint of q-axis current generation and velocity tracking performance in an environment with noise and external load.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.5
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• pp.82-89
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• 2007

AVR(Automatic Voltage Regulator) of exciter control system in AC generator controls voltage and current according to load and terminal voltage variations in order to remain at the bus voltage. The output characteristics of main generator is dependent on the control performance of AVR. This paper presents the PWM type exciter system with transient response compensator for robust control of load variations. Additional transient response compensator generates compensation signal for load variation. So the proposed excitation control system has fast dynamic response in transient period and can control terminal voltage constantly. The proposed method is verified by the computer simulation and experimental results in prototype generation system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.2003-2008
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• 2012

A drive system is necessary to operate LED by an LED illumination system. Because Switched Mode Power Supply (SMPS) is higher in efficiency in the large capacity than Linear Regulator, it is used mainly and controls this in an analog form or digital method. A MCU and a DSP of the digital control central processing unit were higher in a unit price than existing analog control chip, so that an approach was not easy for application of SMPS. But it can take the earnings by it lets you integrate various digital control features like an LED illumination system in one MCU, and realizing a whole system. In this paper, we suggest the algorithm that can improve LED driving current in applying such a digital control method using low-priced type MCU.

• Journal of IKEEE
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• v.20 no.3
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• pp.260-264
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• 2016

The MAX77846, which is compatible with MAX77826, is a sub-power management IC (PMIC) for the latest Wearable Watch and 3G/4G smart phones. The MAX77846 contains N-MOSFET (N channel Metal-Oxide Semiconductor Field-Effect Transistor), a high-efficiency regulator, and comparator, etc to power up peripherals. The MAX77846 also provides power on/off control logic for complete flexibility and an $I^2C$ (Inter Integrated Circuit) serial interface to program individual regulator output voltages. In this paper, the simplified power macro-model based on MAX77846 is designed to verify the performance of the battery voltage in terms of current and time, and simulated by using of the LTspice. In addition, it is verified how much time can the charged battery capacity for Samsung Galaxy Gear 2 be used to operate a specified function after measuring the currents flowing to carry out the main functions in real time, which will be applicable to design parameters for the advanced power module

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.585-588
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• 2014

This paper presents a self-powered sensor node circuit using photovoltaic and vibration energy harvesting. The harvested energy from a solar cell and a vibration device(PZT) is stored in a storage capacitor. The stored energy is managed by a PMU(Power Management Unit). In order to supply a stable voltage to the sensor node, an LDO(Low Drop Out Regulator) is used. The LDO drives a temperature sensor and a SAR ADC(Successive Approximate Register Analog-to-Digital Converter), and 10-bit digital output data corresponding to current temperature is obtained. The proposed circuit is designed in a 0.35um CMOS process, and the designed chip size including PADs is $1.1mm{\times}0.95mm$.

• IMMUNE NETWORK
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• v.22 no.3
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• pp.21.1-21.21
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• 2022

As far the current severe coronavirus disease 2019 (COVID-19), respiratory disease is still the biggest threat to human health. In addition, infectious respiratory diseases are particularly prominent. In addition to killing and clearing the infection pathogen directly, regulating the immune responses against the pathogens is also an important therapeutic modality. Sirtuins belong to NAD+-dependent class III histone deacetylases. Among 7 types of sirtuins, silent information regulator type-1 (SIRT1) played a multitasking role in modulating a wide range of physiological processes, including oxidative stress, inflammation, cell apoptosis, autophagy, antibacterial and antiviral functions. It showed a critical effect in regulating immune responses by deacetylation modification, especially through high-mobility group box 1 (HMGB1), a core molecule regulating the immune system. SIRT1 was associated with many respiratory diseases, including COVID-19 infection, bacterial pneumonia, tuberculosis, and so on. Here, we reviewed the latest research progress regarding the effects of SIRT1 on immune system in respiratory diseases. First, the structure and catalytic characteristics of SIRT1 were introduced. Next, the roles of SIRT1, and the mechanisms underlying the immune regulatory effect through HMGB1, as well as the specific activators/inhibitors of SIRT1, were elaborated. Finally, the multitasking roles of SIRT1 in several respiratory diseases were discussed separately. Taken together, this review implied that SIRT1 could serve as a promising specific therapeutic target for the treatment of respiratory diseases.

• Journal of Microbiology
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• v.41 no.3
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• pp.175-182
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• 2003

Production of ribosomally synthesized antimicrobial peptides usually referred to as bacteriocins is an inducible trait in several gram positive bacteria, particularly in those belonging to the group of lactic acid bacteria. In many of these organisms, production of bacteriocins is inducible and induction requires secretion and extracellular accumulation of peptides that act as chemical messengers and trigger bacteriocin production. These inducer peptides are often referred to as autoinducers and are believed to permit a quorum sensing-based regulation of bacteriocin production. Notably, the peptides acting as autoinducers are dedicated peptides with or without antimicrobial activity or the bacteriocins themselves. The autoinducer-dependent induction of bacteriocin production requires histidine protein kinases and response regulator proteins of two-component signal transduction systems. The current working model for the regulation of class II bacteriocin production in lactic acid bacteria and the most relevant direct and indirect pieces of evidence supporting the model are discussed in this minireview.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.947-951
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• 2008

Subsidiary business between mobile carriers and handset manufacturers has been banned by Korean regulator due to the concern that it may cause the unfair competition in the market. But the opinion that the current regulation has to be consolidated is increasing to follow recent market trends, ensuer the fair competition and increase the users' benefit. In this paper, I analysed trends of the mobile telecommunication market and proposed desirable direction of regulatory improvement.

• International Journal of Control, Automation, and Systems
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• v.1 no.1
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• pp.1-10
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• 2003

This paper presents a high-precision magnetically levitated (maglev) stage to meet demanding motion specifications in the next-generation precision manufacturing and nanotechnology. Characterization of dynamic behaviors of such a motion stage is a crucial task. In this paper, we address the issues related to the stochastic modeling of the stage including transfer function identification, and noise/disturbance analysis and prediction. Provided are test results on precision dynamics, such as fine settling, effect of optical table oscillation, and position ripple. To deal with the dynamic coupling in the platen, we designed and implemented a multivariable linear quadratic regulator, and performed time-optimal control. We demonstrated how the performance of the current maglev stage can be improved with these analyses and experimental results. The maglev stage operates with positioning noise of 5 nm rms in $\chi$ and y, acceleration capabilities in excess of 2g(20 $m/s^2$), and closed-loop crossover frequency of 100 Hz.