• Journal of Biomedical Engineering Research
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• v.42 no.4
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• pp.193-200
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• 2021

Flowmeter and oxygen sensors are listed in COVID-19 essential medical devices. This article reports a Teensy microcontroller-based Oxygen mass flow controller (MFC), core part of the oxygen respirator or extracorporeal membrane oxygenation (ECMO). The developed MFC consisting of the microcontroller, MEMS flow sensor, and solenoid valve was able to accurately control 0 to 100 sccm of oxygen flow rate. The pressure of vacuum chamber increased proportionally to the flow rate (0.998 of Pearson correlation coefficient). The experimental results proved that the developed MFC exhibits comparable performance to a commercial MFC in accuracy, settling time, linearity with pressure, and repeatability of oxygen mass flow control. It is expected that this simple and cheap MFC is utilized for oxygen therapy against the severe acute respiratory syndrome coronavirus 2.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.3
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• pp.264-269
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• 2013

Since MFC(macro-fiber composite) transducer has been developed, many researchers have tried to apply this transducer on SHM(structural health monitoring), because it is so flexible and durable that it can be easily embedded to various kinds of structures. The objective of this paper is to figure out the benefits and feasibility of applying MFC transducers to guided wave technique. For this, we have experimentally tested the performance of MFC patches as transmitter and sensors for excitation and reception of guided waves on the thin aluminum alloy plate. In order to enhance the signal accuracy, we applied the FIR filter for noise reduction as well as used STFT(short-time Fourier transform) algorithm to image the guided wave characteristics clearly. From the results, the guided wave generated based on MFC showed good agreement with its theoretical dispersion curves. Moreover, the ultrasonic Lamb wave techniques based on MFC patches in pitch-catch manner was tested for detection of surface notch defects of which depths are 10%, 20%, 30% and 40% of the aluminum plate thickness. Results showed that the notch was detectable well when the notch depth was 10% of the thickness or greater.

• Smart Structures and Systems
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• v.25 no.5
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• pp.559-567
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• 2020

Vibration at the tip of various flexible manipulators may affect their operation accuracy and work efficiency. To suppress such vibrations, the feasibility of using MFC actuators and sensors is investigated in this paper. Considering the convergence of the famous filtered-x least mean square (FXLMS) algorithm could not be guaranteed while it is employed for vibration suppression of plants with varying secondary path, this paper proposes a new multiple model switching adaptive control algorithm to implement the real time active vibration suppression tests with a new multiple switching strategy. The new switching strategy is based on a cost function with reconstructed error signal and disturbance signal instead of the error signal from the error sensor. And from a robustness perspective, a new variable step-size sign algorithm (VSSA) based FXLMS algorithm is proposed to improve the convergence rate. A cantilever beam with varying tip mass is employed as flexible manipulator model. MFC layers are attached on both sides of it as sensors and actuators. A co-simulation platform was built using ADAMS and MATLAB to test the feasibility of the proposed algorithms. And an experimental platform was constructed to verify the effectiveness of MFC actuators and sensors and the real-time vibration control performance. Simulation and experiment results show that the proposed FXLMS algorithm based multiple model adaptive control approach has good convergence performance under varying load conditions for the flexible cantilever beam, and the proposed FX-VSSA-LMS algorithm based multiple model adaptive control algorithm has the best vibration suppression performance.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1295-1299
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• 2003

The Mass Flow Controller(MFC) has become crucial in semiconductor manufacturing equipments. It is an important element because the quality and the yield of a semiconductor process are decided by the accurate flow control of gas. Therefore, the demand for the high speed and the highly accurate control of MFCs has been requested. It is hard to find an article of the control algorithm applied to MFCs. But, it is known that commercially available MFCs have PID control algorithms. Particularly, when the system detects the flow by way of heat transfer, MFC control problem contains the time delay and the nonlinearity. In this presentation, MFC control algorithm with the superior performance to the conventional PID algorithm is discussed and the superiority is demonstrated through the experiment. Fuzzy controller was utilized in order to compensate the nonlinearity and the time delay, and the performance is compared with that of a product currently available in the market. The control system, in this presentation, consists of a personal computer, the data acquisition board and the control algorithm carried out by LabWindows/CVI program on the PC. In addition, the method of estimating an actual flow from sensor output containing the time delay and the nonlinearity is presented. In conclusion, according to the result of the experiment, the proposed algorithm shows better accuracy and is faster than the conventional controller.

• Journal of the Semiconductor & Display Technology
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• v.7 no.2
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• pp.55-58
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• 2008

The objective of the research is to design, manufacture and test a Mass Flow Controller(MFC) capable of measuring compressible fluid flows based on a "bucket and stop-watch"method. The basic principle is the measurement of time, where the time taken to fill and empty a bucket of known volume is measured. This method of flow measurement is a new concept when compared to a commercilized current mass flow controller. For the flow meter to be able to compete with established designs it not only must be comparable in cost and robustness, it must be very accurate and reliable as well. This device should be able to handle fluid flows in the range of 0.1ml/min to 10ml/min within an accuracy of ${\pm}$1%. A possible application for a device such as this is in electronics industry where arsenic gas is used in the production of silicon chips.

• Journal of Biomedical Engineering Research
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• v.39 no.5
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• pp.208-212
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• 2018

Microbial fuel cell (MFC) technology has been attractive since it can not only treat organic waste in an eco-friendly way by digesting it but also generate electricity by the unique metabolic process of microbes. However, it hasn't been employed in practical use until now because it is hard to integrate a small electricity up to an adequate amount of electric power and difficult to keep its bio-electric activity consistent. In this study, we combined an energy harvester with MFC (MFC-EH) to make the power-integration convenient and developed an energy self-sustainable wireless sensor system driven by a stable electric power produced by MFC-EH. Additionally, we build the low power application measuring data to be cast by the web in real-time so that it can be quickly and easily accessed through the internet. The proposed system could contribute to improvement of waste treatment and up-cycling technologies in near future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.11
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• pp.3913-3934
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• 2021

Real-time prediction of Web service of quality (QoS) provides more convenience for web services in cloud environment, but real-time QoS prediction faces severe challenges, especially under the cold-start situation. Existing literatures of real-time QoS predicting ignore that the QoS of a user/service is related to the QoS of other users/services. For example, users/services belonging to the same group of category will have similar QoS values. All of the methods ignore the group relationship because of the complexity of the model. Based on this, we propose a real-time Matrix Factorization based Clustering model (MFC), which uses category information as a new regularization term of the loss function. Specifically, in order to meet the real-time characteristic of the real-time prediction model, and to minimize the complexity of the model, we first map the QoS values of a large number of users/services to a lower-dimensional space by the PCA method, and then use the K-means algorithm calculates user/service category information, and use the average result to obtain a stable final clustering result. Extensive experiments on real-word datasets demonstrate that MFC outperforms other state-of-the-art prediction algorithms.

• Membrane Journal
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• v.30 no.4
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• pp.213-227
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• 2020

As unrenewable energy resources have depleted over the years, the demand for renewable energy has increased promoting research for more effective methods to produce renewable energy. The field of fuel cell development, specifically microbial fuel cells (MFCs), has developed because of the dual performance potential of the technology. MFCs convert power by facilitating electrode-reducing organisms such as bacteria (microbes) as a catalyst to produce electrical energy. MFCs use domestic and industrial wastewater as fuel to initiate the process, purifying the wastewater as a result. Proton exchange membranes (PEM) play a crucial role in MFCs as a separator between the anodes and cathodes chambers allowing only protons to effectively pass through. Nafion is the commercially used PEM for MFCs, but there are many setbacks: such as cost, production time, and less effective proton conductivity properties. In this review there will be largely two parts. Firstly, several newly developed PEM are discussed as possible replacements of Nafion. Secondly, MFC based on PEM, blended PEM and composite PEM are summarized.

• Composites Research
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• v.36 no.6
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• pp.429-434
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• 2023

In this study, aimed at improving the existing acoustic emission sensor for real time monitoring, a macro-fiber composite (MFC) transducer was employed as the acoustic emission sensor in the gas leak detection system. Prior to implementation, structural analysis was conducted to optimize the MFC's design. Consequently, the flexibility of the MFC facilitated excellent adherence to curved pipes, enabling the reception of acoustic emission (AE) signals without complications. Analysis of AE signals revealed substantial variations in parameter values for both high-pressure and low-pressure leaks. Notably, in the parameters of the Fast Fourier Transform (FFT) graph, the change amounted to 120% to 626% for high-pressure leaks compared to the case without leaks, and approximately 9% to 22% for low-pressure leaks. Furthermore, depending on the distance from the leak site, the magnitude of change in parameters tended to decrease as the distance increased. As the results, in the future, not only will it be possible to detect a leak by detecting the amount of parameter change in the future, but it will also be possible to identify the location of the leak from the amount of change.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.9
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• pp.531-538
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• 2005

This paper proposes an expert system which is able to enhance the accuracy and productivity by determining the test strategy based on heuristic rules for test of the hybrid electronic circuit board producted massively in production line. The test heuristic rules are obtained from test system designer, test experts and experimental results. The guarding method separating the tested device with circumference circuit of the device is adopted to enhance the accuracy of measurements in the test of analog devices. This guarding method can reduce the error occurring due to the voltage drop in both the signal input line and the measuring line by utilizing heuristic rules considering the device impedance and the parallel impedance. Also, PSA(Parallel Signature Analysis) technique Is applied for test of the digital devices and circuits. In the PSA technique, the real-time test of the high integrated device is possible by minimizing the test time forcing n bit output stream from the tested device to LFSR continuously. It is implemented in Visual C++ computer language for the purpose of the implementation of the inference engine using the dynamic memory allocation technique, the interface with the electronic circuit database and the hardware direct control. Finally, the effectiveness of the builded expert system is proved by simulating the several faults occurring in the mounting process the electronic devices to the surface of PCB for a typical hybrid electronic board and by identifying the results.