• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.114-121
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• 2004

The sensor and measuring instrument that are used for the infrastructure is discussed the reliability problem from the various environment factors. In the domestic infrastructure, the low reliability products are produced, because of lack of the pertinent test methods and equipments. To improve the practical use and accuracy of the sensor, it raises the measurement reliability about the sensor and measurement instrument. In this study, the variance of the displacement value according to temperature was investigated using the LVDT for the infrastructure. The experimental results showed that a sensor is affected by environment factor such as temperature.

• Journal of Information Processing Systems
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• 제10권3호
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• pp.412-428
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• 2014

Request oriented sensor networks have stricter requirements than conventional event-driven or periodic report models. Therefore, in this paper we propose a minimum energy data aggregation (MEDA), which meets the requirements for request oriented sensor networks by exploiting a low power real-time scheduler, on-demand time synchronization, variable response frame structure, and adaptive retransmission. In addition we introduce a test bed consisting of a number of MEDA prototypes, which support near real-time bidirectional sensor networks. The experimental results also demonstrate that the MEDA guarantees deterministic aggregation time, enables minimum energy operation, and provides a reliable data aggregation service.

• 한국컴퓨터정보학회논문지
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• 제20권11호
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• pp.63-68
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• 2015

In this paper, we propose a new energy efficient scheme which can prolong the life of sensor networks, it should be able to reduce the number of sensing. We use the concept of safe zone for manage the appropriate range of properties. We measure the distance between the sensed temperature value and the center of the zone, and calculate the next sensing interval based on this distance. We name our proposed scheme "VIS". To assess the performance of the proposed scheme the actual temperature data was collected using the sensor node. The algorithm was implemented through the programming and was evaluated in a variety of settings. Experimental results show that the proposed algorithm is to significantly reduce the number of sensing in terms of energy efficiency while having the ability to know the state of the sensor nodes periodically. Our VIS algorithm can be useful in applications which will require the ability of control to the temperature within a proper range.

• 한국산업정보학회논문지
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• 제15권5호
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• pp.29-35
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• 2010

본 논문에서는 광센서를 이용하여 컬러 디스플레이 장치를 사용하는 다양한 주위 조명광을 판별할 수 있는 시스템을 구현하였다. 디스플레이를 사용하는 외부 조명광을 판별하기 위해서 Ye와 Cy 두 출력을 갖는 광센서를 사용하여 조명광 판별 시스템을 구현하였고, 구현한 실제 시스템에 대한 실험 결과 조도가 변하는 다양한 조명광에 대해서 광센서의 출력 전압비(Ye/Cy)로 조명광의 판별이 가능한 것을 확인하였다.

• 센서학회지
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• 제20권6호
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• pp.406-411
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• 2011

$Co_3O_4$ thick film gas sensor using the powder prepared by hydrothermal reaction method(HRM) was fabricated. For comparison study, we also prepared the sensor using commercial $Co_3O_4$ powder under the same fabrication conditions. Sensitivity, time response, and selectivity of them to variable gases such as iso-$C_4H_{10}$, CO, $NH_3$, and $CH_4$ were investigated. The sensor from the powder prepared by HRM showed higher sensitivity to every gas than those from commercial powder. For iso-$C_4H_{10}$ gas, the sensitivities of both sensor to 100 ppm are 160 % and 40 %, respectively. Time response and selectivity of the sensor using the powder prepared by HRM were better than those of the sensor using commercial powder.

• 센서학회지
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• 제11권4호
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• pp.200-208
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• 2002

This paper represents the development of an array-type flexible tactile sensor using PVDF(polyvinylidene fluoride) film and flexible circuitry. The tactile sensor which has $8{\times}8$ taxels is made by using PVDF film and FPC(flexible printed circuit) technique. Experimental results on static and dynamic properties are obtained by applying arbitrary forces and frequencies generated by the shaker. In the static characteristics, the threshold and the linearity of the sensor are investigated. Also dynamic response of the sensor subjected to the variable frequencies is examined. The signals of a contact force to the tactile sensor are sensed and processed in the DSP system in which the signals are digitalized and filtered. Finally, the signals are integrated for taking the force profile. The processed signals of the outputs of the sensor are visualized on a personal computer, the shape and force distribution of the contacted object are obtained using two and three-dimensional image in real time. The reasonable performance for the detection of contact state is verified through the experiment.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2011년도 추계학술논문집 2부
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• pp.385-388
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• 2011

This study is about development of remote controlled bollard using the BLDC motor mechatronics theory. A bollard is composed of the sensor part and the control part. The sensor part is consisted of sensors that detect the locations of a bollard. The role of the control part are adjusting motor speed and power through variable resistance. In order to confirm required performance, The speed of decent and ascent of the bollard, the time and the RPM of BLDC motor were tested according to the variable resistance and the load.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1380-1383
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• 1996

This paper presents a recoil and counter recoil(R&CR) motion measurement method using linear variable differential transformers(LVDT). The output of a LVDT is obtained from the differential voltage of the 2nd transformers. As a sensor core is attached at the motion body, the output is directly proportional to the core motion. Displacement, velocity and acceleration are measure from the core length. With a comparison between the measurement result and the known value which is obtained by the precision steel tape, the accuracy and the usefulness of the proposed scheme is validated.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.286-293
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• 2004

The air fuel ratios of current gasoline engines are almost controlled by several air flow meters. When CVVT (Continuous Variable Valve Timing) is applied to a gasoline engine for higher engine performance, the MAP (Manifold Absolute Pressure) sensor is difficult to follow the instantaneous air fuel ratio due to the valve timing effect. Therefore, a HFM (Hot Film Flow Meter) is widely used for measuring intake air flow in this case. However, the HFMs are incapable of indicating to reverse flow, the oscillation of intake air flow has an negative effect on the precision of the HFM. Consequently, the various duct configurations in front of the air flow sensor affect the precision of HFM sensitivity. This paper mainly focused on the analysis of the reverse flow, flow fluctuation in throttle upstream and the geometry of intake system which influence the HFM measurement.

• 전력전자학회논문지
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• 제22권3호
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• pp.223-230
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• 2017

A low-cost BLDC motor with hall sensor is used to drive the position control of a facility security monitoring system in this paper. Low measurable frequency of the hall sensor signal in low-speed regions results in difficulty in obtaining accurate speed detection and position control. To improve system control performance, we propose a variable gain of position controller and stop mode control scheme according to the motor speed and error position with pre-set deceleration time. The proposed stop mode control scheme is activated around the stop position to forcibly move the BLDC motor to the stop position in low speed. In the proposed stop mode, the motor current is controlled by the actual speed with the reference rotating angle. The control performance of the proposed position control is verified through experiments at the actual rail guided facility security monitoring system.