• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1994.06b
• /
• pp.54-58
• /
• 1994

본 연구에서는 가변용량형 사판식 액시얼 피스톤 펌프의 가변용량 시스템에 있어서 actuator piston의 가공정도와 실린더사이의 간극의 변화에 따른 응답성 및 누설용량에 끼치는 영향을 살펴보았다. 가변용량형 사판식 액시얼 피스톤 펌프는 사판의 각도를 조절함으로써 유량을 조절하게 된다. 사판의 각도조절은 actuator piston에 의해 행해지며, 가변용량부의 어느 설정압력에 도달하면, 이 actuator piston이 사판을 밀어 사판의 각도를 변화 시키게 된다. 지배방정식으로는 spool과 사판의 운동방정식과 각 chamber의 누설 유량이 있다. 이들 방정식을 \ulcorner으로써 각 부분의 운동을 해석할 수 있게 된다. 여기에서 해석이 어려운 부분은 각 계수들의 결정이며 simulation을 할 때는 이로한 계수들을 이론적으로 결정을 하게 되고, 실험을 통해 검증하도록 한다. 즉, 각 운동뷰의 감쇠계수와 각 오리피스를 통한 유량계수, 그리고 감쇠계수 등은 실험을 통해 검토한다. 실험을 통한 측정에서는 각 chamber의 압력은 각 chamber에 연결된 압력센서 3개에 의해 행해지며, 사판의 각도는 angle 센서에 의해 측정하게 된다. 그리고 actuator piston과 블럭 사이의 간극을 조절하여 누설계수를 변화시키며, 그 영향을 살펴보았다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.509-512
• /
• 2015

In this paper, several capacitive sensors for measuring the position of the piston in hydraulic cylinder was studied and designed. The inductive LVDT sensor has been widely used to measure the position of the piston because of its high accuracy, but this type of sensor is very expensive and has difficulty in use because of its complexity. To overcome these disadvantages, we studied the optimized non-contact capacitive sensors and designed several capacitive sensors for accurate measuring the location of piston in hydraulic cylinder. The proposed capacitive sensor has the possibility of practical use for hydraulic cylinder through experiments.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.11
• /
• pp.1147-1156
• /
• 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 Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.487-490
• /
• 1995

This paper discisses the effects geometric errors on the measurement of error motions of rotor with the cylindrical capacitive displacement sensor. Analytic model of the measuring process with this sensor is derived and this model shows that the effect of geometric errors of sensor is larger than that of rator on the measurement of error motions of rotor. The computer simulation shows effect of periodic errors in this sensor on the measuring orbit.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.795-797
• /
• 2013

This paper describes a charge sharing capacitive-sensing circuit technique that improves the quality of images captured with fingerprint sensor LSIs. When the finger is dry, the electrical resistance of a finger surface is high. It leads to poor image quality. To capture clear images even when the finger is dry, the modified capacitive detection circuit improves the image quality using an enhancement plate at the finger surface and a voltage control circuit. The test circuit is analyzed on $0.35{\mu}m$ CMOS process.

• 한국HCI학회:학술대회논문집
• /
• 2007.02a
• /
• pp.573-577
• /
• 2007

터치 센서를 이용한 휴대단말용 인터페이스가 다양하게 개발되면서 차세대 인터랙션 수단으로서 많은 주목을 받고 있지만, 버튼 인터페이스에 비해 오동작에 취약하고 터치 인터페이스만의 차별성을 확보하지 못하고 있는 실정이다. 본 논문에서는 터치 드래그 동작을 주요 인터랙션 수단으로 활용한 모바일 기기용 사용자 인터페이스를 개발하여 오동작을 최소화하고 사용자가 조작할 때 즐거움을 줄 수 있는 UI 요소로 활용할 수 있도록 하였다. 본 논문에서 개발한 터치 인터페이스는 기기의 내부/외부 방향의 스크롤 동작을 각각 drag-in/drag-out 동작으로 칭하고 이러한 드래그 동작을 응용 프로그램의 실행과 종료에 할당하였으며 터치 센서를 따라 움직이는 스크를 동작은 기존과 동일하게 일반적인 스크롤 행위를 지시하는데 적용하였다. 제안한 인터랙션 방법은 터치 센서의 형태에 따라 크게 두 가지 방식으로 구현하였다. 첫 번째 방법은 기기 스크린 외곽에 터치 센서를 이열(二列) 배치하여, 터치스크린을 사용하지 않고도 스크린 주변의 터치 센서를 활용한 drag-in/out 동작의 감지가 가능하도록 하였다. 두 번째 구현 방법은 정전용량형 터치 센서 IC를 활용해 터치 스크린 기능과 함께 스크린 주변의 기기 케이스의 일부까지도 사용자의 접촉을 감지할 수 있도록 하였다. 기존 저항 방식 터치 스크린과 달리 본 논문에서 활용한 방식은 스크린과 케이스에서 동시에 터치를 감지할 수 있으며, 다접점 감지 알고리즘의 개발로 두 개의 손가락을 이용한 다양한 터치 인터랙션으로 활용할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.10a
• /
• pp.96-98
• /
• 2014

Wireless Sensor Network(WSN) is a wireless real-time information(Acquired from the sensor nodes that have the computing power and wireless communication capabilities.) collected, and to take advantage of processing techniques. Currently it is very diverse, such as environmental monitoring, health care, security, smart home, smart grid applications is that. Thus it is required in the wireless sensor network, the algorithm for the efficient use of the limited energy capacity. Suggested by the algorithm for selecting a cluster head node for a hybrid type and clustered, by comparing the amount of energy remaining and a connection between the nodes In this paper, we aim to increase efficiency and accuracy of the wireless sensor network.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.2
• /
• pp.225-229
• /
• 2011

In this study, capacitive type pressure sensors based on low temperature co-fired ceramics (LTCC) technology for environmental monitoring were demonstrated. The LTCC is one of promising technology than is based one since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.) for sensor application. Especially, it has good mechanical and chemical properties for robust environmental application. The 3D LTCC diaphragm with thickness of 400 ${\mu}m$ were fabricated by laminating 4 green sheets using commercial powder (NEG, MLS 22C). To evaluate the sensing properties of the different cavity areas, two types of diaphragm which had different cavity areas with 25, 49 $mm^2$ respectively, were fabricated. To realize capacitive type pressure sensor, the Au top electrode was fabricated using thermal evaporator and the bottome electrode was compressed using aluminium foil. The sensing properties of the fabricated sensors showed linear characteristic under different pressure (0~30 psi) using pressure measurement system.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.2
• /
• pp.147-152
• /
• 2015

We designed, fabricated, and tested the capacitive microsensors for skin piloerection monitoring. The performance of the skin piloerection monitoring sensor was characterized using the artificial bump, representing human skin goosebump; thus, resulting in the sensitivity of $-0.00252%/{\mu}m$ and the nonlinearity of 25.9 % for the artificial goosebump deformation in the range of $0{\sim}326{\mu}m$. We also verified two successive human skin piloerection having 3.5 s duration on the subject's dorsal forearms, thus resulting in the capacitance change of -6.2 fF and -9.2 fF compared to the initial condition, corresponding to the piloerection intensity of $145{\mu}m$ and $194{\mu}m$, respectively. It was demonstrated experimentally that the proposed sensor is capable to measure the human skin piloerection objectively and quantitatively, thereby suggesting the quantitative evaluation method of the qualitative human emotional state for cognitive human-machine interfaces applications.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.9
• /
• pp.13-21
• /
• 2011

In this paper, the CMOS programmable interface circuit for MEMS gyroscope is presented, and evaluated with the MEMS sensing element. The circuit includes the front-end charge amplifier with 10 bit programmable capacitor arrays, 9 bit DAC for accurate offset calibration, and 10 bit PGA for accurate gain calibration. The self oscillation loop with automatic gain control operates properly. The offset error and gain error after calibration are measured to be 0.36 %FSO and 0.19 %FSO, respectively. The noise equivalent resolution and bias instability are measured to be 0.016 deg/sec and 0.012 deg/sec, respectively. The calibration capability of this circuit can reduce the variations of the output offset and gain, and this can enhance the manufacturability and can improve the yield.