• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.985-988
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• 2001

A piezo-buzzer being used for the purpose of generation of audible frequency, which is a electric-acoustic transducer utilizing the inverse piezoelectric effect. Also it can be used for a pressure sensor according to the piezoelectric effect. But the output of a piezo-buzzer is a differential signal. In this study, we've made a system that can measure a real pressure by integration of output signal. According to our results, it could be found a possibility of application for pressure sensor by measurement of output characteristics when a piezo-buzzer was pressurized and depressurized, and by measuring of an error by means of the drift current of OP-Amp, etc..

• ETRI Journal
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• v.29 no.1
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• pp.70-78
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• 2007

A new low-voltage CMOS interface circuit with digital output for piezo-resistive transducer is proposed. An input current sensing configuration is used to detect change in piezo-resistance due to applied pressure and to allow low-voltage circuit operation. A simple 1-bit first-order delta-sigma modulator is used to produce an output digital bitstream. The proposed interface circuit is realized in a 0.35 ${\mu}m$ CMOS technology and draws less than 200 ${\mu}A$ from a single 1.5 V power supply voltage. Simulation results show that the circuit can achieve an equivalent output resolution of 9.67 bits with less than 0.23% non-linearity error.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1390-1393
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• 2002

Comparative analysis of driving inverters for piezo-electric transformer (PT) is performed and the suit- able drive circuit for portable devices such as personal digital assistants (PDA) is chosen with the experiment in this paper. As a result, a single-switch inverter with a small two winding reactor is chosen, and then the advantages of this method are clarified. It is also confirmed that the driving inverter with this method enables to realize a stabilized AC 400v output and 82% power efficiency from DC 3V input under the conditions of the variations of load current or input voltage from the experiments. Piezo-electric Transformer, Back-Light System, Single-Switch Driving Circuits, Control Method

• Journal of ILASS-Korea
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• v.25 no.1
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• pp.1-7
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• 2020

In the common rail fuel injection system, which is the core of diesel high efficiency and NO_X reduction, injection strategies such as high pressure injection of fuel, accurate injection rate control, and multistage injection are important to increase fuel atomization. In this study, the bypass type piezo injector for the electronic control based common rail injection system applied to diesel fuel vehicle was studied. In particular, the injection rate and internal fuel flow characteristics of the high-pressure injector according to the piezo stacking number and applied voltage were analyzed by theoretical numerical method. When the applied voltage changes, it is determined that additional fuel flow through the bypass compensates for the reduced valve driving force due to the change in the driving voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.172-175
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• 2000

The crimping connection is a permanent connection that maintains mechanical and electrical property for a long time by crimping two conductors. In this paper, we have done a basic study to decide normal or abnormal condition depending on crimping. Using PZT piezo-sensor, we have analyzed crimping waveforms according to the crimping height. And hence the normal or abnormal condition of crimping connections in real time could be decided by comparison of crimping waveforms in the cases of normal crimping, over crimping, under crimping and core omitting.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.245-246
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• 2009

정전용량형 후막 스트레인 게이지(piezocapacitive thick film strain gage)는 세라믹 ($Al_2O_3$)을 주 원료로 하는 지지대(약 5mm)와 다이어프램(약 $300{\mu}m$) 그리고 가드 링으로 구성된다. 전극 판은 도전성 페이스트를 이용하여 지지대와 다이어프램에 형성되었으며 극판 사이에는 유전체 메이스트를 사용하여 스크린 인쇄로 후막을 형성하였다. 극판 사이의 가드 링 두께는 약 $30{\mu}m$정도로 다이어프램의 변위 최대값을 유지시키는 데 필요한 간격이다. 따라서 정전용랑형 후막 스트레인 게이지는 지지대를 중심으로 다이어프램에 압력 (0.5~1.0bar)이 인가될 때 변위를 발생시키면서 커패시터 값이 압력의 크기에 따라 비례 특성을 가지고 변화하는 것을 이용한 것이다. 압력이 없을때 초기값은 35pF~40pF 정도이고 정격압력의 최대치를 인가시켰을 때 약 55pF~55p를 나타내었다.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.772-775
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• 2004

Generally, arterial pulse waves are measured at the radial arterial of wrist or carotid arterial of neck using a sensor such as pressure sensor, piezoelectric sensor or optic sensor. But in this paper, arterial pulse wave is measured at the temple using PZT piezo sensor which is attached on the temple in form of a hair-band. Arterial Pulse waves are generally measured when a reagent is in a static state. But in this paper, we implemented the arterial pulse wave measurement system, as a previous stage of the arterial pulse wave measurement system for running at outdoors or on a running machine, that measures arterial pulse waves at the temple, which is the least moving part when running. Thorough the continuous study, if the motion artifact when running is possible to be removed, the system will be able to perform monitoring of running men's states and especially emergency signals such as serious pulse waves of an/old and feeble persons and handicapped persons.

• Journal of ILASS-Korea
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• v.24 no.2
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• pp.66-72
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• 2019

Diesel vehicles suffer from poor starting and running problems at cold temperatures. Diesel vehicles have the characteristic that CO and PM are reduced or similarly discharged when going from low temperature to high temperature. In this study, a bypass type piezo injector for electronic control based common rail injection system was used. Numerical analysis using injector drive analysis model was performed to analyze injector drive and internal fuel flow characteristics according to fuel temperature change. The results show that the rate of density change due to the fuel temperature is proportional, and that the effect of the kinematic viscosity is relatively large between $-20^{\circ}C$ and $0^{\circ}C$. Comparing the results of temperature condition at $0^{\circ}C$ and $20^{\circ}C$, it is considered that the viscosity is more correlated with the needle displacement than the pressure chamber of the delivery chamber.

• Journal of Sensor Science and Technology
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• v.26 no.2
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• pp.107-113
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• 2017

Energy source of a piezo-electric harvester is vibration. Sources of vibration are machineries operated with high frequencies, constructions and people operated with low frequencies and etc. In this study, we tried to figure out power generation properties over vibrations upon angles of a piezo-cantilever for applying them to movements of the construction and/or people, which are vibration sources at low frequencies. A uni-morph cantilever with a $59mm{\times}29mm{\times}0.2mm$ piezo-electric element attached on a $71mm{\times}46mm{\times}0.25mm$ copperplate was used. A spring was attached to the lower side of the cantilever and a mass was attached on the opposite side. Also, a structure with a specific angle which is an angle in between the ground and the cantilever was prepared and then, connected to a spring or the cantilever. Then, this structure was divided into the A-type and B-type and excited in the direction of z- axis. After that, the angle between the ground and the cantilever was changed and excited by 1 to 10 Hz upon the existence of a spring and/or a mass to compare power generation properties.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.38-48
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• 2014

In this paper, a design of Signal Processing Analog Front-End IC for Automotive Piezo-Resistive Type Pressure Sensor is presented. In modern society, as the car turns to go from mechanical to electronic technology, the accuracy and reliability of electronic parts required importantly. In order to improve these points, Programmable Gain Amplifier (PGA) amplifies the received signal in accordance with gain for increasing the accuracy after PRT Sensor is operated to change physical pressure signals to electrical signals. The signal amplified from PGA is processed by Digital blocks like ADC, CMC and DAC. After going through this process, it is possible to determine the electrical signal to physical pressure signal. As processing analog signal to digital signal, reliability and accuracy in Analog Front-End IC is increased. The current consumption of IC is 5.32mA. The die area of the fabricated IC is $1.94mm{\times}1.94mm$.