• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.153-161
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• 2022

Physical activities are decreasing and sitting time is increasing due to the automation, smartization, and intelligence of necessary household items throughout daily life. Recent healthcare studies have reported that the likelihood of obesity, diabetes, cardiovascular disease, and early death increases in proportion to sitting time. In this paper, we develop a sitting posture correction cushion in real time using capacitive pressure sensor based on conductive textile. It develops a pressure sensor using conductive textile, a key component of the posture correction cushion, and develops a low power-based pressure measurement circuit. It provides a function to transmit sensor values measured in real time to smartphones using BLE short-range wireless communication on the posture correction cushion, and develops a mobile application to check the condition of the sitting posture through these sensor values. In the mobile app, you can visualize your sitting posture and check it in real time, and if you keep it in the wrong posture for a certain period of time, you can notify it through an alarm. In addition, it is possible to visualize the sitting time and posture accuracy in a graph. Through the correction cushion in this paper, we experiment with how effective it is to correct the user's posture by recognizing the user's sitting posture, and present differentiation and excellence compared to other product.

• Science of Emotion and Sensibility
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• v.15 no.4
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• pp.415-424
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• 2012

According to introduction of Well-Being lifestyle and ageing society, vital sign monitoring system which can be continued measurement of vital sign has been increased their important in field of the healthcare. Under this trend, Respiration monitoring system has been studied and developed in a various way to apply continued monitoring and non-conscious monitoring system. But, Study of the respiration monitoring system based on consumer needs and usability test is insufficient. In this study, Textile capacitive pressure sensor(TCPS) of belt type was developed and tested it's utility and subjective sensibility. TCPS measures respiration signals and can be derived in real time monitoring. As a result, monitoring respiration using textile capacitive pressure sensor offers a promising possibility of convenient measurement of respiration rate (correlation (r＝0.9553, p<0.0001). In the result of usability and wearability test, all of categorizes(perceived change, wearability, movement, facility of management, usefulness) were received favorable evaluation on usability test( mean value : 3.8), and suitable location of TCPS in the clothing is deriven on the abdomen part. According to synthetical results, Basic smart clothing design based on respiration monitoring system is proposed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.230-236
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• 2001

We developed a built-in sensor bearing to measure the rotor motion of a rolling piston type compressor for the air conditioner. Because of needs for the high efficiency and long life span of compressor, and the usage of alternative refrigerants, the operating condition of the compressor becomes more severe. The accurate measurement of the rotor motion of the compressor can contribute greatly to the design and analysis of the hydrodynamic bearing. However, it is difficult to measure accurately the shaft behavior of small compressor because of the small space for the sensor mount, high temperature and pressure of compressor, oil mixed with refrigerant, and electromagnetic noise of the motor. To overcome these difficulties, we develop the cylindrical capacitive sensor that is built in the hydrodynamic bearing and calibrate the built-in sensor bearing indirectly through measuring the oil relative permittivity. We measured the rotor motion as well as suction and discharge pressures in various conditions. The several experimental results show that the developed built-in sensor bearing can measure the rotor motion not only in steady state but also in transient state.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.3
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• pp.104-109
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• 2018

A non-intrusive ECG and BCG measurement system is introduced. The system is built on a auxiliary backrest of a chair. The developed system is aimed to non-intrusive assessment of cardiovascular dynamic indices such as pulse arrival time(PAT) and pre-ejection period (PEP). In the system, capacitive active electrodes and capacitive grounding were used for the non-intrusive indirect-contact ECG measurement, and EMFi pressure sensor was used for the non-intrusive BCG measurement. The capacitive active electrodes and the EMFi sensor were attached on the backrest. Using the system, ECG and BCG were successfully acquired. The measured BCG showed peaks that following ECG R peaks. It was shown that the time interval between Q wave in ECG and first peak in BCG correlates Pre-ejection period measured by impedance-cardiogram. The results showed that the introduced system can be used for the non-intrusive various cardiovascular information including ECG, PAT, PEP.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1369-1371
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• 2015

본 논문은 전도성섬유 압력센서로 보행신호를 획득하고 걷기, 서기, 앉기, 계단오르기, 계단내려오기 등 총 5가지 행동을 인식하는 시스템을 개발하는 것이 목적이다. 시스템은 Capacitive pressure 센서, CDC(Capacitive to Digital Converter), 마이크로프로세서, 블루투스 모듈, 스마트 폰으로 구성되고 획득한 데이터 패턴을 분류한 결과 평균 99.5%의 높은 인식률을 보였다. 각 발당 한 개의 채널만을 이용해 행동패턴을 인지함으로써 적은 수의 채널로도 행동인지의 가능함을 확인할 수 있었다.

• Journal of Sensor Science and Technology
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• v.31 no.3
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• pp.139-144
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• 2022

Advanced tactile sensors are receiving significant attention in various industries such as extended reality, electronic skin, organic user interfaces, and robotics. The capabilities of advanced tactile sensors require a variety of functions, including position sensing, pressure sensing, and material recognition. Moreover, they should comsume less power and be bio-friendly with human contact. Recently, a tactile sensor based on the triboelectrification effect was developed. Triboelectric tactile sensors have the advantages of wide material availability, simple structure, and low manufacturing cost. Because they generate electricity by contact, they have low power consumption compared to conventional tactile sensors such as capacitive and piezoresistive. Furthermore, they have the ability to recognize the contact material as well as execute position and pressure sensing functions using the triboelectrification effect. The aim of this study is to introduce the progress of research on triboelectrification-based tactile sensors with various functions such as position sensing, pressure sensing and contact material recognition.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.9
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• pp.62-71
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• 2002

An intergral C-V converter is proposed to solve the nonlinearity problem of capacitive pressure sensors. The integral C-V converter consists of a switched-capacitor integrator and a switched-capacitor differential amplifier. It converts the sensor capacitance change which is inversely proportional to an applied pressure into a linear voltage output. Various PSPICE simulations prove that the convertor has excellent characteristics, such as low nonlinearity less than 0.01%/FS and low sensitivity to parallel offset capacitance and parasitic capacitance for the displacement range of sensor diaphragm set to 0 ${\sim}$ 90% of the initial distance between the electrodes in the simulation. We also show that the offset compensation and the gain trimming are easily achieved with the integral C-V converter.

• Journal of Sensor Science and Technology
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• v.5 no.5
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• pp.63-68
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• 1996

In order to implement the integrated capacitive pressure sensors, which contains integrated interface circuits to detect the electrical output signal, several main factors that have a bad effect on the characteristics of sensors must be improved, such as parasitic capacitance effects, temperature/thermal drift, and the leakage current of a readout circuitry. This paper describes the novel design of the dedicated CMOS readout circuitry that is consists of two capacitance to frequency converters and 4 bit digital logic compensating circuits. Dividing the oscillation frequency of a sensing sensor by that of reference sensor, this circuit is designed to eliminate the thermal/temperature drift and the effect of the leakage currents, and to access a digital signals to obtain a high signal-to-noise(S/N)ratio. Therefore, the resolution of this circuit can be increased by increasing the number of the digital bits. Digital compensated circuits of this circuits, except for the C-F converters, are fabricated on a FPGA chip, and fundamental performance of the circuits are evaluated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1147-1156
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• 2011

A contact-type area-varying capacitive displacement sensor, or CLECDiS, can measure displacements over millimeter ranges with nanometer resolution. However, a small changes in the contact condition due to the surface profile or friction, which are inherent characteristics of contact-type sensors, lead to significant distortion of the output signal. Therefore, ensuring reliable contact conditions during CLECDiS measurements is the most important area to be improved in their actual use. Herein, in order to design an instrument for ensuring reliable contact conditions, the contact condition is analyzed by characterizing the signal distortion, observing the pressure distribution between the contacting surfaces, and measuring the motional errors of the sensor using a laser Doppler vibrometer (LDV). The manufactured instrument enables a CLECDiS to be used in an ultraprecise positioning system with improved reliability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.350-351
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• 2006

Thick film mechanical sensors can be categorized into four main areas piezoresistive, piezoelectric, capacitive and mechanic tube. In this areas, the thick film strain gage is the earliest example of a primary sensing element based on the substrates. The latest thick film sensor is used various pastes that have been specifically developed for pressure sensor application. Some elastic materials exhibit a change in bulk resistivity when they are subjected to displacement by an applied pressure. This property is referred to as piezoresistivity and is a major factor influencing the sensitivity of a piezoresistive strain gage. The effect of thick film resistors was first noticed in the early 1970, as described by Holmes in his paper in 1973.