• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.22.5-22
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• 2001

Robust control of a GFR composite beam with a distributed PVDF sensor and piezo-ceramic actuator is presented En this paper. Modal analysis method and modal coordinates are introduced to obtain the state educations of the structural system. 1st and 2nd natural frequencies are considered In the modeling, because robust control theory which is robustness to structured uncertainty is adopted to suppress the vibration. If the controllers designed by H$\^$$\infty$/ theory do not satisfy control performance, it is improved by ${\mu}$-synthesis method with D-K Iteration so that the ${\mu}$-controller based on the structured singular value satisfies the nominal performance and robust performance.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.51-55
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• 2021

With the recent development of various smartphone designs in the smartphone market, the use of curved cover glass has been required, and interest in curved glass production has increased. In this paper, we designed a pressurization system that simplified the size of the system using a wedge amplification mechanism for smartphone curved glass molding systems. The pressurization system consisted of a linear motor, a wedge, and a force sensor. The wedge was used to amplify the force, and the piezoelectric sensor was used to measure the force. In addition, the proposed amplification mechanism was confirmed to have an error of 1.27% through an experiment compared to the simulation, and the pressurization error of 0.76% for the pressurization profile 3,500N was verified through an experiment.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.315-319
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• 2021

Recent impact of 4th industrial revolution is increasing usage of IoT technology along with smartphones and tablet PC. However blue light emitted from electronic devices such as smartphones and tablet PC causes detrimental change to human bodies. As the controversy over the harmfulness of blue light became known through the media and various communities, related markets were formed, and various blocking films, software, and vision protection monitors were released. In this paper focuses on utilizing IoT technology to protect human organizations from blue light. It presents anti-blue light system which prevents excessive exposure to blue light through Arduino module such as ultrasound, piezo buzzer and blue light measurement module.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.11
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• pp.1-8
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• 2005

In this paper, we present design and prototyping of a low-cost, integrated multi-functional micro health sensor chip that can be used or embedded in widely consumer devices, such as cell phone and PDA, for monitoring environmental condition including air pressure, temperature and humidity. This research's scope includes basic individual sensor study, architecture for integrating sensors on a chip, fabrication process compatibility and test/evaluation of prototype sensors. The results show that the integrated TPH sensor has good characteristics of ${\pm}\;1\%FS$ of linearity and hysteresis for pressure sensor and temperature sensor and of ${\pm}\;5\%FS$ of linearity and hysteresis But if we use 3rd order approximation for humidity sensor, full scale error becomes much smaller and this will be one of our future study.

• Structural Monitoring and Maintenance
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• v.1 no.2
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• pp.183-195
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• 2014

Scour is one of the leading causes of overwater bridge failures worldwide. While monitoring systems have already been implemented or are still being developed, they suffer from limitations such as high costs, inaccuracies, and low reliability, among others. Also, most sensors only measure scour depth at one location and near the pier. Thus, the objective is to design a simple, low cost, scour hole topography monitoring system that could better characterize the entire depth, shape, and size of bridge scour holes. The design is based on burying a robust, waterproofed, piezoelectric sensor strip in the streambed. When scour erodes sediments to expose the sensor, flowing water excites it to cause the generation of time-varying voltage signals. An algorithm then takes the time-domain data and maps it to the frequency-domain for identifying the sensor's resonant frequency, which is used for calculating the exposed sensor length or scour depth. Here, three different sets of tests were conducted to validate this new technique. First, a single sensor was tested in ambient air, and its exposed length was varied. Upon verifying the sensing concept, a waterproofed prototype was buried in soil and tested in a tank filled with water. Sensor performance was characterized as soil was manually eroded away, which simulated various scour depths. The results confirmed that sensor resonant frequencies decreased with increasing scour depths. Finally, a network of 11 sensors was configured to form a distributed monitoring system in the lab. Their exposed lengths were adjusted to simulate scour hole formation and evolution. Results showed promise that the proposed sensing system could be scaled up and used for bridge scour topography monitoring.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.79-88
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• 2009

The objective of this study is to develop the new vehicle classification algorithm and minimize classification errors. The existing vehicle classification algorithm collects data from loop and piezo sensors according to the specification("Vehicle classification guide for traffic volume survey" 2006) given by the Ministry of Land, Transport and Maritime Affairs. The new vehicle classification system collects the vehicle length, distance between axles, axle type, wheel-base and tire type to minimize classification error. The main difference of new system is the "Wandering" sensor which is capable of measuring the wheel-base and tire type(single or dual). The wandering sensor obtains the wheel-base and tire type by detecting both left and right tire imprint. Verification tests were completed with the total traffic volume of 762,420 vehicles in a month for the new vehicle classification algorithm. Among them, 47 vehicles(0.006%) were not classified within 12 vehicle types. This results proves very high level of classification accuracy for the new system. Using the new vehicle classification algorithm will improve the accuracy and it can be broadly applicable to the road planning, design, and management. It can also upgrade the level of traffic research for the road and transportation infrastructure.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.18-21
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• 1995

When we inject drugstuffs to a patient for a long time, it is important to control proper injection amount and flow rate. Since inproper injection amount and a flow rate would cause bad a recovery a patient, the relience of sensors which detect injection amount is an important factor for whole injection systems' performance. In this research, we've compared the suitability of three sensors for injection pump monitoring system. The three types of sensors, piezo film sensor, photo transistor made up with three transmitting photodiodes and receving photodiode, and photo array, were selected for comparing. Using suggested data processing technique and photo amy sensors, we could minimize the effect of interference, disturbance, illumanation change, and sensitivity change caused by sensor's position. According to the experiments, the photo amy showed the higher reliance than any other the three types of sensors. The developed systems could be the foundation of beginning home production of infusion pump system and available for the base model of whole monitoring and control systems.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.132.2-132.2
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• 2011

We are developing Adaptive Optics (AO) system for astronomical use. The He-Ne laser works as an artificial light source. The tip-tilt correction servo is added to our AO system. The tip-tilt term, among the Zernike terms, is the biggest contributor of wavefront deformation caused by atmospheric turbulence at small telescopes. The tip-tilt correction servo consists of a Piezo tip-tilt platform with a mirror, a quadrant photodiode as a tip-tilt sensor, and controllers. The Shack-Hartmann wavefront sensor measures the residual wavefront errors and they are corrected by the MEMS (Micro Electro Mechanical System) deformable mirror. The MEMS deformable mirror allows the compact size at low cost compare to adaptive secondary mirror and other deformable mirrors. As the frame rates of the MEMS deformable mirror is about tens of kHz, the frame rates of the detector in wavefront sensor is the bottleneck of the wavefront correction speed. For faster performance, we replaced a CCD which provides frame rates only 70 Hz with a CMOS with frame rates up to 450 Hz.

• Smart Structures and Systems
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• v.6 no.2
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• pp.167-182
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• 2010

An adaptronic strut for machine tools with parallel kinematics for compensation of the influence of geometric errors is introduced. Implemented within the strut is a piezoelectric sensor-actuator unit separated in function. In the first part of this contribution, the functional principle of the strut is presented. For use of one piezoelectric transducer as both, sensor and actuator as so-called self-sensing actuator, the acquisition of the sensing signal while actuating simultaneously using electrical bridge circuits as well as filter properties are examined. In the second part the control concept developed for the adaptronic strut is presented. A co-simulation model of the strut for simulating the controlled multi-body behavior of the strut is set-up. The control design for the strut as a stand-alone system is tested under various external loads. Finally, the strut is implemented into a model of the complete machine tool and the influence of the controlled strut onto the behavior of the machine tool is examined.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.11
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• pp.66-69
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• 1991

This paper describes a design of transducer for non-invasively detecting pressure radial pulse wave in aterial system and a recording system that for the studing the aterial pulse diagnosis of korean traditional medicine. The mechanism of transducer is composed of sensing mechanism, pressure sensor, conditioning amplifier. The variation of radial pulse pressure in the sensing mechanism is converted to the electric signal by piezo-resistive pressure sensor and it converted to the digital signal after preprocessing via A/D converter. The converted signals inputed to the computer as data files and then it display to the monitor for waveform watching and this datas can be used as the aterial pulse diagnosis data. This system effectively detect non-differential radial pulse wave and we conside that if analizing the recorded radial pulse wave, compared each other, it can be helpful in quantify radial pulse wave diagonosis of the Korean traditional medicine.