Earticle

교류 전압의 위상을 검출하여 제어하는 시스템의 경우 아날로그 제어방식에서는 검출한 위상에 대해 필터링에 의한 위상 offset 부분을 보상하여 제어에 응용하고 있다. 그러나, 디지털 제어방식에서는 이러한 위상 검출을 이용하여 제어할 경우 마이크로프로세서 혹은 마이크로 컨트롤러의 동작 주파수와 입력 위상 시간과의 오차로 인하여 정밀한 제어 를 이룰 수가 없다. 일반적으로 사용하는 방식이 일정한 시간이 되면 누적된 오차를 임의로 보상하여 맞추어주는 방식인 데 이러한 경우 보상하기 전까지는 오차를 지속적으로 가지고 갈 수밖에 없는 상황이 발생하게 된다. 이러한 문제점을 해결하기 위해서는 실시간으로 영점을 검출하여 마이크로프로세서의 동작 주파수에 맞도록 보상하는 방법이 필요하게 된다. 따라서 이러한 오차를 줄이면서 정밀한 디지털 제어에 응용하기 위해 본 논문에서 수행하고자 하는 연구는 다음과 같다. 1) 시뮬레이션 모델링을 통해 Zero Crossing Detection 알고리즘을 구현하여 영점을 검출을 통하여 동작 주파수 에 맞도록 보상하는 방법에 관해 연구. 2) Microcontroller를 이용한 Zero Crossing Detection 설계를 통하여 실시간 으로 영점을 검출하여 마이크로프로세서의 동작 주파수에 맞도록 보상하는 방법에 관해 연구. 3) Zero Crossing Detection 회로를 활용하여 BLDC 전동기의 회전자 위치 추정 연구.

In the case of a system that detects and controls the phase of an alternating voltage, the analog control method compensates the phase offset part by filtering for the detected phase and applies it to the control. However, in the digital control method, precise control cannot be achieved due to an error between the operating frequency of the microprocessor or the microcontroller and the input phase time when controlled using such phase detection. In general, when the method used is a certain time, the accumulated error is compensated and adjusted at random. To solve this problem, a method of detecting a zero point in real time and compensating for the operating frequency of the microprocessor is needed. Therefore, the research to be performed in this paper to reduce these errors and apply them to precise digital control is as follows. 1) Research on how to implement Zero Crossing Detection algorithm through simulation modeling to compensate the zero point to match the operating frequency through detection. 2) A study on the method of detecting zero points in real time through the Zero Crossing Detection design using a microcontroller and compensating for the operating frequency of the microprocessor. 3) A study on the estimation of the rotor position of BLDC motors using the Zero Crossing Detection circuit.

This paper parabolic satellite antenna aims to track the precise location of a moving ship or, in the car that can be used to design the system. That was previously used with the reaction rate of a stepping motor, BLDC motor, in order to suppress the noise two-axis control and a separate encoder to the six degrees of freedom motion system was implemented in a precise location. In order to overcome various disturbances gyro sensor Yaw, Pitch, Roll 3 axes were used. To respond immediately to the disturbance at the same time, two-axis motor by controlling the precise location of the system was designed to compensate instantaneously. In addition, the circle tracking algorithm has applied for our system. We designed that the AGC signal of digital tuner quickly had gone to up to the maximum point. In order to solve the various communication errors such as moving the antenna or ground, we had designed the control system

A Novel Two-Phase Brushless Tubular Linear Motor And Its Precise Positioning Control System Are Presented In This Paper. The Magnetic Field Distribution In The Air Gap Of The Linear Motor Is Trapezoidal With Optimization By Halbach Magnet Array, And An Ironless Structure Is Adopted To Eliminate Force Ripples. A Simple And Practical Controller Called Active Disturbance Rejection Controller Is Used To Implement Positioning Control Of The Linear Motor Prototype, Which Is Affected By Parameter Uncertainties And Friction. Simulation And Experimental Results Show That The Position Step Response Is Smooth And Micrometer Positioning Accuracy Is Achieved Without Significant Overshoot Or Oscillation. It Can Be Concluded That The Proposed Linear Motor Is Suitable For Smooth And Precise Linear Motion Applications.

The multistage compression is usually adopted for large tonnage powder pressing equipment to improve product quality. The first compression is the key process during the powder processing as the target pressure is small and the load is great fluctuant. The pressure in the first compression is likely to be much overshot that makes laminated products if conventional control strategy is applied. The control parameters of routine mode have bad adaptation because they change with the target pressure. In order to improve the accuracy of the pressure and adaptability of control parameters in the first compression, one strategy oriented to engineering application that includes data testing, parameter setting and control optimizing has been proposed. Real-time monitoring system with multi-channels based on LabVIEW is built, and the full-state of equipment can be acquired based on the system. The working statuses of control elements during the pressing process due to inertial force are optimized with the experimental data, and the segmented variable gain control strategy based on parameterization is developed and applied. The experimental results with the strategy during the first compression indicate that the pressure precision is raised from 0.3MPa and above (conventional opened-loop control) to 0.05MPa and below, and the pressing time is controlled in 300ms and below. The control strategy ensures the high accuracy and efficiency of pressing process and it is convenient to be applied in engineering.

According to the control requirements of miniature precise cutting machine, this paper designs the control system of this cutting machine by the method of combing OMRON CP1H PLC and Eview MT506L touch panel. The control system uses PLC as its core, has completed in receiving the limiting I/O signal and upper computer communication signal and deals with the centralized processing according to the PLC interior design procedure and finally has realized the logic control of a frequency converter and three stepper motors. The touch panel is used for the man-machine intercommunication interface, completes the function of operation and display, and realizes the intellectualization and humanization of the cutting process. The experimental results show that the system is novel in design and has a friendly operation interface and advanced technology, can realize the high precision cutting of the workpiece.

Parkinson's disease (PD) is one of the most common neurodegenerative diseases in the elderly population and is caused by the loss of dopaminergic neurons. PD has been predominantly attributed to mitochondrial dysfunction. The structural alteration of α-synuclein triggers toxic oligomer formation in the neurons, which greatly contributes to PD. In this article, we discuss the role of several familial PD-related proteins, such as α-synuclein, DJ-1, LRRK2, PINK1, and parkin in mitophagy, which entails a selective degradation of mitochondria via autophagy. Defective changes in mitochondrial dynamics and their biochemical and functional interaction induce the formation of toxic α-synuclein-containing protein aggregates in PD. In addition, these gene products play an essential role in ubiquitin proteasome system (UPS)-mediated proteolysis as well as mitophagy. Interestingly, a few deubiquitinating enzymes (DUBs) additionally modulate these two pathways negatively or positively. Based on these findings, we summarize the close relationship between several DUBs and the precise modulation of mitophagy. For example, the USP8, USP10, and USP15, among many DUBs are reported to specifically regulate the K48- or K63-linked de-ubiquitination reactions of several target proteins associated with the mitophagic process, in turn upregulating the mitophagy and protecting neuronal cells from α-synuclein-derived toxicity. In contrast, USP30 inhibits mitophagy by opposing parkin-mediated ubiquitination of target proteins. Furthermore, the association between these changes and PD pathogenesis will be discussed. Taken together, although the functional roles of several PD-related genes have yet to be fully understood, they are substantially associated with mitochondrial quality control as well as UPS. Therefore, a better understanding of their relationship provides valuable therapeutic clues for appropriate management strategies.

This paper reports a simple and versatile technique for generating highly controllable sinusoidal nanostructures on the surface of poly-(dimethylsiloxane) (PDMS). The sinusoidal features were generated by oxidizing PDMS slabs with oxygen plasma, then stretching them by wrapping around a cylinderical surface, and finally allowing them to relax. The wavelength and amplitude could be finely controlled by varying the fabrication conditions such as duration of oxidation, diameter of the glass cylinder, duration of stretching, thickness of the PDMS slabs, and temperature during the second hardening process. The varied trends of the buckling patterns were characterized by using an atomic force microscope.

Silicon nitride ceramics with various α/β phase ratio were fabricated by controlling sintering conditions of PECS process. Mechanical properties varied systematically with α/β ratio. Young's modulus and hardness increased with α-Si₃N₄ volume fraction, and fracture strength and toughness increased with β-Si₃N₄ content.

The ultra precision linear stage is an essential device in the fields of MEMS and Bio technology. A piezo electric motor is widely used for its better linear characteristics, faster response time, and smaller size than conventional electro-magnetic actuator. We develop a new inchworm type motor to implement an actuator-integrated a long stroke linear stage which can move fast. To implement a servo system, we use a heterodyne interferometer as a position sensor, and we propose a new measurement technique using I/Q demodulator, and we propose a counting method to measure the position of fast moving object with low cost circuitry. The characteristics of the actuator and servo system are evaluated by measuring its displacement with a commercial laser interferometer.

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position, because the position of rotor is an essential information. Although high resolution optical encoders or resolvers are used to provide a precise position information, these sensors are expensive. Moreover, in the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost analog encoder suitable for practical applications is proposed. And the control algorithm to generate switching signals using a Simple digital logic is presented. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.

Metal-oxide-semiconductor field-effect transistors (MOSFETs)의 critical dimension (CD)가 sub 45 nm로 줄어듬에 따라 기존에 gate dielectric으로 사용하고 있는 SiO2에서 발생되는 high gate leakage current 때문에 새로운 high dielectric constant (k) 물질들이 연구되기 시작하였다. 여러 가지 high-k 물질 중에서, aluminum-oxide (Al2O3)는 높은 dielectric constant (~10)와 전자 터널링 barrier height (~2eV) 등을 가지기 때문에 많은 연구가 되고 있다. 그러나 Al2O3를 anisotropic한 patterning을 하기 위해 주로 사용되고 있는 halogen-based 플라즈마 식각 과정에서 나타나는 Al2O3와 하부 layer간의 낮은 식각 selectivity 뿐만 아니라 표면에 발생되는 defect, stoichiometry modification, roughness 변화 등의 많은 문제점들로 인하여 device performance가 감소하기 때문에 이를 해결하기 위한 많은 연구들이 진행중이다. 따라서 본 연구에서는 실리콘 기판위의 atomic layer deposition (ALD)로 증착된 Al2O3를 BCl3/Ar 중성빔을 이용하여 원자층 식각한 후 식각 특성을 분석해 보았다. Al2O3 표면을 BCl3로 absorption시킨 후 Ar 중성빔으로 desorption 시키는 과정에서 volatile한 aluminum-chlorides와 boron oxychloride가 형성되어 layer by layer로 제거됨을 관찰 할 수 있었다.

Momentum flywheels are widely applied for the generation of small and precise torque for the attitude control and inertial stabilization of satellites and space stations. Due to its inherited system nonlinearity, the tracking performance of the flywheel torque/speed in dynamic/plug braking operations is limited when a conventional controller is employed. To take advantage of the well-separated two-time-scale quantities of a flywheel driving system, the singular perturbation technique is adopted to improve the torque tracking performance. In addition, the composite control law, which combines slow- and fast- dynamic portions, is derived for flywheel driving systems. Furthermore, a novel control strategy for plug braking dynamics, which considers couplings between the Buck converter and the three-phase inverter load, is designed with easy implementation. Finally, experimental results are presented to demonstrate the correctness of the analysis and the superiority of the proposed methods.

This paper presents a macro/micro flip chip mounting head system for precise force control. In the proposed macro/ micro system, the macro actuator is conventional do servomotor with a ball screw mechanism and the micro actuator is a voice coil motor(VCM) that consists of four NdFeB magnets and a winded moving coil. For force control, a sensitive strain-gauge force sensor is mounted in the micro actuator. Through harmonic motion between macro and micro actuator, we would like to get precise contact force control when small sized flip chip is mounted on flexible substrate in high speed. In order to show the effectiveness of the proposed macro/micro flip chip mounting head system, we com...

The control system of a precise positioning mechanism with resonance and Coulomb friction has been designed using H$_{\infty}$ control theory, and the control performance has been verified by computer simulation and experimental analysis. The DGKF type H$_{\infty}$ control theory with scalar weighting factors was utilized for designing the control system. The followings have been confirmed from the present study: (1) The system with H$_{\infty}$ control presents better convergence and stability than the system with conventional control (PI-notch filter control). (2) The H$_{\infty}$ control system have good robustness properties for a wide range of operating conditions in the presence of external disturbances such as Coulomb friction and changing mechanical resonant frequency.ncy.

The boehmite precursors with high surface area have been obtained using aluminum isopropoxide (AIP) and deionized water as starting materials and have been transformed into α-alumina after annealing at 1200o C for 2 hrs. Aluminum isopropoxide was purified with hydrolysis reaction with isopropyl alcohol for 1 hr by stirring at 120 rpm at 80o C. A highly selective and very sensitive spectrophotometric method was used to determine the trace amounts of each element in the synthesized alumina samples.

This paper addresses an intelligent uncertainty function to improve the robust stability and performance of $H_{\infty}$ controlled system in terms of reduced conservatism. The system is identified, out-put performance and control signal requirements are controlled by proper selection of performance and control weighting functions. Adaptive Neuro Fuzzy Inference System (ANFIS) learns the uncertainty bounds of model uncertainty that results from unmodeled dynamics and parameter variations, then the developed uncertainty weighting function will be included in the synthesis of the $H_{\infty}$ controller. $\nu$-gap measure is utilized to validate the intelligent identified uncertainty bounds and measure the stability of the designed $H_{\infty}$ controlled system as well. Experimental results on a servo motion system reveal the advantages of combining intelligent uncertainty identification and robust control. Improved performance is achieved. The proposed approach also allows for iterative experiment design.