• Current Research on Agriculture and Life Sciences
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• v.32 no.3
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• pp.159-163
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• 2014

Agricultural unmanned helicopters have become a new paradigm for aerial application. Yet, such agricultural helicopters require easy and affordable attitude control systems. Therefore, this study presents an affordable attitude measurement system using a DCM (direction cosine matrix) algorithm that would be applied to agricultural unmanned helicopters. An IMU using a low-cost MEMS and an algorithm to estimate the attitude of the helicopter were applied in a gimbals structure to evaluate the accuracy of the attitude measurements. The estimation errors in the attitude were determined in comparison with the true angles determined by absolute position encoders. The DCM algorithm and sensors showed an accuracy of about 1.1% for the roll and pitch angle estimation. However, the accuracy of the yaw angle estimation at 3.7% was relatively larger. Such errors may be due to the magnetic field of the stepping motor and encoder system. Notwithstanding, since the intrinsic behavior of the agricultural helicopter remains steady, the determination of attitude would be reliable and practical.

• Tribology and Lubricants
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• v.37 no.6
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• pp.203-207
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• 2021

This study presents the development of dielectric constant sensors to measure lubricant properties. The lubricant oil sensor is used to measure oil properties and machine conditions. Various condition monitoring methods are applied to diagnose machine conditions. Machine condition monitoring using oil sensors has advantage over other machine condition monitoring methods. The fault conditions can be noticed at the early stages by the detection of wear particles using oil sensors. Therefore, it provides an early warning in the failure procedure. A variety of oil sensors are applied to check the machine condition. Among all oil sensors, only one sensor can measure the tendency of several properties such as acidity and water content. A dielectric constant sensor is also used to measure various oil properties; therefore, it is very useful. The dielectric constant is the ratio of the capacitance of a capacitor using that material as a dielectric to that of a similar capacitor using vacuum as its dielectric. The dielectric constant has an effect on water content, contaminants, base oil, additive, and so forth. In this study, the dielectric constant sensor is fabricated using MEMS process. In the fabrication process, the shape, gap of the electrode array, and thickness of the insulation material are considered to improve the sensitivity of the sensor.

• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.164-167
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• 2006

Calorimeter is one of widely used biosensors. Conventional or existing calorimeters are realized directly on a silicon wafer which has very high thermal conductivity. It results in decreasing temperature difference between junctions and it makes a sensitivity of calorimeter to be decreased. In this study, the microcalorimeter was made by using MEMS(Micro Electro Mechanical Systems)-technology and hot junctions of the microcalorimeter are released from a silicon substrate to reduce loss of generated heat by reactions between biomolecules. Sensitivity of the released microcalorimeter was 18 mV/M which is 1.5 times higher than another calorimeters on silicon substrate by reactions between biotin and streptavidin.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1218-1223
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• 2007

A surface micro machined angular rate sensor utilizing a vibrating MEMS structure on a silicon has been developed. These tuning fork angular rate sensors are extremely rugged, inherently balanced, and easy to fabricate. The device is fabricated using a temperature compensation method based on automatic gain control technique. A linearity of approximately 0.6%, limited by the on-chip electronics has been obtained with this new sensor. Tests of the sensor demonstrate that its performance is equivalent to that required for implementation of a yaw control system. Vehicle handling and safety are substantially improved using the sensor to implement yaw control.

• Smart Structures and Systems
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• v.12 no.6
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• pp.679-694
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• 2013

In this paper the application of the Interpolation Damage Detection Method to the numerical model of a suspension bridge instrumented with a network of Micro-Electro-Mechanical System sensors is presented. The method, which, in its present formulation, belongs to Level II damage identification method, can identify the presence and the location of damage from responses recorded on the structure before and after a seismic damaging event. The application of the method does not require knowledge of the modal properties of the structure nor a numerical model of it. Emphasis is placed herein on the influence of recorded signals noise on the reliability of the results given by the Interpolation Damage Detection Method. The response of a suspension bridge to seismic excitation is computed from a numerical model and artificially corrupted with random noise characteristic of two families of Micro-Electro-Mechanical System accelerometers. The reliability of the results is checked for different damage scenarios.

• Electronics and Telecommunications Trends
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• v.28 no.5
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• pp.83-92
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• 2013

IT 기술이 발달함에 따라 저전력, 초소형 센서노드를 설치하여 무인으로 정보를 얻을 수 있는 시스템의 도입이 점차 확대되는 추세이며, 이것을 위하여 온도, 습도, 가스 등 환경정보를 획득할 수 있는 센서뿐만 아니라 초소형 저전력 복합환경센서 ROIC(Read-Out Integrated Circuit)의 중요성이 증가하고 있다. 또한 휴대폰, 노트북, 스마트폰, 태블랫 PC 등의 모바일 IT 제품들은 빠르게 소형화, 슬림화, 저전력화 되고 있다. 이런 시스템의 요구에 따라 음향부품도 기본적인 음향감지/출력 성능 이외에 크기 및 소모전력이 중요한 기능요소로 크게 부각되고 있으며, 이것을 위하여 소형화, 저가격화가 가능한 MEMS(Microelectromechanical Systems) 음향센서 및 ROIC 개발이 요구되고 있다. 따라서 본고에서는 복합환경센서 ROIC 및 MEMS 마이크로폰 ROIC의 기술동향 등에 대해서 고찰하고자 한다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1472-1473
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• 2008

Polyimide thin films were cured locally using MEMS microhotplates. The polyimide locally cured at temperature over 350$^{\circ}C$ for 1 hour was fully cured. There was no significant difference between polyimide thin films cured in a conventional convection oven and those cured locally on MEMS microhotplates. The locally cured polyimide humidity sensor showed a linearity of 0.9995, a sensitivity of 0.77 pF/%RH, a hysteresis of 0.6 %RH, and a response time of 3s. These results indicate that the locally-cured polyimide films may be used as dielectric material of high speed, highsensitivity humidity sensors.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1761-1766
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• 2008

This paper deals with a novel autocalibration method of three-axis micromachined accelerometers applied to a new golf swing diagnosis equipment for golfers. This diagnosis equipment can help golfers monitor and anlalyze their swing posture and therefore modify their swing action to get better score and enjoy their lives through golf. The micromachined accelerometers to get information of the motion are the essential part of the putting club to measure the three-axis acceleration as accurately as possible. This paper presents an efficient autocalibration algorithm to find the offset and sensitivity of accelerometers by only using the static measurement data at six different positions. The experimetnal results on the developed putters show the validity of the proposed algorithm for the new smart putter.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1767-1772
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• 2008

A microcantilever is a well-known MEMS structure for sensing bio-chemical molecules. When bio-chemical molecules are adsorbed on the microcantilever's surface, resonance frequency shift is generated. There are two issues in this phenomena. The first one is which one between mass change and surface stress change effects is more dominant on the resonance frequency shift. The second one is what will be the performance change when the boundary condition is changed from cantilevers to double clamped beams. We have studied the effect of surface stress change and compared it with that of mass change by using FEM analysis. Furthermore, for microstructures having different boundary conditions, we have studied Q-factor, which determines the detection limit of micro/nano mechanical sensors.

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.374-378
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• 2012

Biofouling causes many problem in industrial processes, medical health industries, water utilities and our daily life. So detecting formation of biofilm on the surface of medical appliance, water pipe and industrial utility is highly important to prevent the problem caused by biofouling. In this study, we suggest an electrochemical sensor for detecting biofilm. We fabricated the electrochemical sensor in MEMS process and cultivated two different kinds of Pseudomonas aeruginosa RpoN type and Wild type on the surface of electrochemical sensor. Each group of Pseudomonas aeruginosa was cultivated according to the hours of 2, 4, 6, 8, 12 and 24. Then we investigated changes in degree of biofilm cultivation using cyclic voltammetry. As a result, it was observed that peak of the cyclic voltammetry curve is increased according as the biofilm growth on the surface of electrochemical sensor. Also we can discern between Pseudomonas aeruginosa RpoN type and Wild type.