• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1951-1958
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• 2011

The objective of this study is to analyze the performance of digital low-pass differentiators(LPD) and then to provide a method to select effective LPD filter, for detecting spikes of surface motor unit action potentials(MUAP). The successful spike detection of MUAPs is a first important step for EMG signal decomposition. The performances of simple and weighted LPD(SLPD and WLPD) filters are analyzed based on different filter lengths and varying MUAPs from simulated surface EMG signals. The SNR improving coefficient and effective MUAP duration range from the analysis results can be used to select proper LPD filters under the varying conditions of surface EMG.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.615-623
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• 2016

The paper describes a hysteretic buck converter including a differentiator and an adaptive hysteresis window controller. Differentiating the feedback signal achieves ultra-fast switching of the buck converter. The adaptive hysteresis window control allows a monotonous operation with predictable noise spectrum, and gives way to efficient design for variable supply and output voltages. The measurement results in a $0.13-{\mu}m$ CMOS process indicated that the switching frequency became double times higher, and the voltage ripple was reduced by up to 69%. They also indicated that the normalized switching frequency variation was reduced by 74% with variable $V_{DD}$ and by 63% with variable $V_{OUT}$. The power efficiency was improved by 3.5% depending on loading condition.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.931-933
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• 1989

If the nonlinear term in a nonlinear control system equation can be deleted by state feedback control, the original system becomes a linear system. For this linear control system, many well known methods may be used to handle it, and then reverse it back to nonlinear form. Many problems of nonlinear control systems can be solved in this way. In this paper, this method will be used to transfer the identification problem of nonlinear systems into a linear control problem. The nonlinear observer is established by constructing linear observer. Then the state control of nonlinear systems is realized. Finally, the technique of the PID controller obtained by using bang-bang tracker as a differentiator provides a stronger robust controller. Even though the method in this paper may not theoretically perfect, many numerical simulations show that it is applicable.

• Journal of Information Technology Services
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• v.10 no.1
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• pp.167-176
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• 2011

Punctuality is one of the key performance indicators of the airline industry and an important service differentiator especially for valuable customers. In addition, improvement on time performance can help achieve cost saving, i.e. the cost of airline report, which could range from 0.6% to 2.9% of their operating revenues. Therefore efficient management of punctuality is crucial for the industry. This study overcomes the limitations of existing analyses on punctuality and develops a multi-dimensional model for airport punctuality analysis. In addition to analysis of airport punctuality, visual analysis is also proposed in the study. Data was collected from actual flight data of Incheon International Airport. Using the new visual analysis method, the study discovered the pattern of the punctuality that has never studied before.

• Journal of Drive and Control
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• v.10 no.4
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• pp.22-28
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• 2013

Mechanical and electrical properties of a DDV(Direct Drive servo Valve) with electric feedback are analysed via reverse analysis technique in this work. The DDV is disassembled and mechanical parameters, such as spool mass, spring stiffness and port size are identified. The servo amplifier, which is built in the valve, is reversely analysed and the control scheme and gains for several control actions are also identified. The electrical feedback for spool displacement improves much better the valve performance, such as hysteresis and dynamic bandwidth frequency, than an ordinary mechanical feedback valve. Integrating control action with very large gain was adopted in the valve amplifier, and it seemed to give high performance.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1075-1085
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• 2018

To deal with the operation performance degradation of permanent magnet synchronous machine (PMSM) drives with uncertainties and unmodeled dynamics, this paper presents a finite-time nonlinear disturbance observer (FTNDO) based discretized integral sliding mode (DISM) composite control scheme. Based on the reaching-law approach, a DISM speed controller featuring a superior dynamic quality and global robustness against disturbances is constructed. This controller can avoid the reaching phase and overlarge control action. In addition, a sliding mode differentiator based FTNDO is devised and extended to the discrete-time domain for disturbance estimation. The attractive features of the FTNDO are that it can provide a finite-time converging estimation and alleviate the chattering effect in conventional sliding mode observers, while retaining robustness to parameter variations. By feeding the estimate forward to the pre-stage DISM controller, both disturbances and chattering can be significantly suppressed. Moreover, considering the estimation error of a FTNDO caused by discrete sampling, a stability analysis of the composite controller is discussed. Experimental results validate the superiority of the presented scheme.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1389-1399
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• 2015

This research suggests maximum power point tracking (MPPT) for the solar photovoltaic (PV) power scheme using a new constant voltage (CV) fractional order incremental conductance (FOINC) algorithm. The PV panel has low transformation efficiency and power output of PV panel depends on the change in weather conditions. Possible extracting power can be raised to a battery load utilizing a MPPT algorithm. Among all the MPPT strategies, the incremental conductance (INC) algorithm is mostly employed due to easy implementation, less fluctuations and faster tracking, which is not only has the merits of INC, fractional order can deliver a dynamic mathematical modelling to define non-linear physiognomies. CV-FOINC variation as dynamic variable is exploited to regulate the PV power toward the peak operating point. For a lesser scale photovoltaic conversion scheme, the suggested technique is validated by simulation with dissimilar operating conditions. Contributions are made in numerous aspects of the entire system, including new control algorithm design, system simulation, converter design, programming into simulation environment and experimental setup. The results confirm that the small tracking period and practicality in tracking of photovoltaic array.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1130-1133
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• 2008

In this paper, a mini-Electrocardiograph(ECG) system operated by a general 9V alkaline battery is designed and implemented. The manufactured ECG consists of the instrumentation amplifier stage for detecting and amplifying the heart signal, the high pass filter(HPF), the low pass filter(LPF), the differentiator cirduit, and the peak detector. The detected heart signal through three leads is displayed cleanly on the oscilloscope, which shows the good operation of our ECG. As the detected heart signal is digitalized and displayed on the small LCD unit, the convenience of easy checkup and portability of the implemented ECG can be largely improved. Therefore, whenever and wherever anyone may checkup his/her cardiac state with ease.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.3
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• pp.65-72
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• 2018

The purpose of this paper is to understand the influence of country personality dimensions and product involvement on European consumers purchase and visit intentions, considering the Portuguese context. The increasing economic globalisation has resulted in the reducing of trade barriers between nations and the availability of more foreign products and services across borders. Therefore, the place associations of these products and services might be regarded as a potential competitive differentiator in their respective markets. Despite the proliferation of literature devoted to assessing the effects of country-of-origin, the symbolic dimension of a country's image remains understudied. A questionnaire measuring country personality dimensions, product involvement, and consumer's purchase and visit intention was passed on a sample of 335 European consumers. Country personality indeed matters both positively and negatively. Findings show that while assiduousness positively influences consumer's visit intentions, wickedness has a negative influence on consumer's purchase intentions. Findings also reveal that product involvement has a positive significant influence on consumer's purchase and visit intentions. On developing marketing strategies, international marketers and governmental decision-makers should consider product involvement attributes and specific country personality traits to provide the country's products with a competitive edge, as well as to promote the country as a travelling destination.

• International Journal of Control, Automation, and Systems
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• v.3 no.spc2
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• pp.296-301
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• 2005

As a new control strategy, the Nonlinear PID (NLPID) controller has been introduced successfully in power systems. The controller is free of planting model groundwork during the design procedure and is therefore able to be achieved quite simply. In this paper, a nonlinear PID controller used for a superconducting magnetic energy storage (SMES) unit connected to a power system is proposed. The purpose of designing such a controller is to improve the stability of the power system in a relatively wide operation range. The design procedure takes into account the active and reactive power cooperative control scheme as well as the simple structure so as to be more apt to practical utilization. Simulation is carried out to investigate the performance of the proposed controller in a high order nonlinear power system model under the. MATLAB environment. The results show satisfactory performance and good robustness of the controller. The feasibility of the controller is testified as well.