• Progress in Superconductivity and Cryogenics
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• v.14 no.4
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• pp.46-49
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• 2012

The selection of the temperature sensor in the cryogenic system depends on the temperature range, shape and accuracy. The accuracy of the temperature sensor is essential to improve the reliability of experiment. We have developed the variable temperature cryostat using a two-stage cryocooler. In order to reduce heat load, thermal shield is installed at the first stage with MLI (Multiple layer insulation). We have also developed the sensor holder calibrating more than twenty sensors at the same time for saving time and money. The system can calibrate sensor at variable temperature by controlling electric heater. In this paper, we present design and fabrication of variable temperature cryostat and representative result of Cernox sensor calibration.

• Journal of Biosystems Engineering
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• v.42 no.2
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• pp.98-103
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• 2017

Purpose: Precision agriculture includes determining the right amount of nitrogen for a specific location in the field. This work focused on developing and validating a model using variable rate nitrogen application based on the estimated SPAD value from the ground-based image sensor. Methods: A variable rate N application based on the decision making system was performed using a sensor-based variable rate nitrogen application system. To validate the nitrogen application decision making system based on the SPAD values, the developed N recommendation was compared with another conventional N recommendation. Results: Sensor-based variable rate nitrogen application was performed. The nitrogen deficiency level was measured using the image sensor system. Then, a variable rate application was run using the decision model and real-ti me control. Conclusions: These results would be useful for nitrogen management of corn in the field. The developed nitrogen application decision making system worked well, when considering the SPAD value estimation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.4
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• pp.355-360
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• 2013

A wireless intraocular (IOP) pressure sensor based on micro electro mechanical system (MEMS) technology is proposed. The proposed IOP sensor uses variable inductance according to the external pressure. The proposed sensor is composed of two flexible membranes: a ferrite bottom part, an inductor, and a capacitor. The inductance of the sensor varies according to the external pressure. The resonance frequency of the sensor is also varied, and this frequency is detected using an external coil. The external coil is designed with an FR-4 printed circuit board. The feasibility of the proposed sensor structure using variable inductance to detect the external pressure is successfully demonstrated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.364-372
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• 2006

In this paper, we present a finger tip tactile sensor which can detect contact normal force as well as slip. The sensor is made up of two different materials, such as polyvinylidene fluoride (PVDF) known as piezoelectric polymer, and pressure variable resistor ink. In order to detect slip on the surface of the object, two PVDF strips are arranged along the normal direction in the robot finger tip and the thumb tip. The surface electrode of the PVDF strip is fabricated using silk-screening technique with silver paste. Also a thin flexible force sensor is fabricated in the form of a matrix using pressure variable resistor ink in order to sense the static force. The developed tactile sensor is physically flexible and it can be deformed three-dimensionally to any shape so that it can be placed on anywhere on the curved surface. In addition, a tactile sensing system is developed, which includes miniaturized charge amplifier to amplify the small signal from the sensor, and the fast signal processing unit. The sensor system is evaluated experimentally and its effectiveness is validated.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1808-1813
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• 2005

In this paper, we present the finger tip tactile sensor which can detect contact normal force as well as slip. The developed sensor is made of two different materials, such as polyvinylidene fluoride(PVDF) that is known as piezoelectric polymer and pressure variable resistor ink. In order to detect slip to surface of object, a PVDF strip is arranged along the normal direction in the robot finger tip and the thumb tip. The surface electrode of the PVDF strip is fabricated using silk-screening technique with silver paste. Also a thin flexible force sensor is fabricated in the form of a matrix using pressure variable resistor ink in order to sense the static force. The developed tactile sensor is physically flexible and it can be deformed three-dimensionally to any shape so that it can be placed on anywhere on the curved surface. In addition, we developed a tactile sensing system by miniaturizing the charge amplifier, in order to amplify the small signal from the sensor, and the fast signal processing unit. The sensor system is evaluated experimentally and its effectiveness is validated.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.283-285
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• 2005

To account for the importance of variable in multi-sensor data fusion, random forests are applied to supervised land-cover classification. The random forests approach is a non-parametric ensemble classifier based on CART-like trees. Its distinguished feature is that the importance of variable can be estimated by randomly permuting the variable of interest in all the out-of-bag samples for each classifier. Supervised classification with a multi-sensor remote sensing data set including optical and polarimetric SAR data was carried out to illustrate the applicability of random forests. From the experimental result, the random forests approach could extract important variables or bands for land-cover discrimination and showed good performance, as compared with other non-parametric data fusion algorithms.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.196-198
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• 2006

Ubiquitous Computing 시대가 도래하면서 USN은 다양한 분야에 적용되고 결국 지능형 유비쿼터스 센서 네트워크로 진화될 것이다. 센서네트워크는 네트워크를 구성하는 일정지역에 많은 수의 센서 노드가 배치되는 만큼 그에 따른 가장 큰 제약조건은 유한한 battery수명이다. 따라서 가용에너지가 작은 sensor node를 에너지 효율성을 고려하여 제작해서 적은 에너지 소모를 가지는 long-life sensor node를 만든다면 보다 현실적인 USN 실현에 가까이 갈수 있다. 여기에 우리는 DVS(Dynamic Voltage Sealing)라는 scheme을 기반으로 power-efficiency sensor node을 제작하였다. Variable Voltage을 CPU에 공급하거나 사용하지 않는 state에 있는 경우의 RF transceiver, clock, sensor등을 on/off control함으로서 성능향상을 가할 수 있다.

• Journal of Communications and Networks
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• v.12 no.5
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• pp.510-517
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• 2010

In this paper, an adaptive MAC protocol (variable load adaptive (VLA)-MAC) is proposed for wireless sensor networks. This protocol can achieve high energy efficiency and provide low latency under variable-traffic-load conditions. In the case of VLA-MAC, traffic load is measured online and used for adaptive adjustment. Sensor nodes transmit packets in bursts under high load conditions to alleviate packet accumulation and reduce latency. This also removes unnecessary listen action and decreases energy consumption in low load conditions. Simulation results show that the energy efficiency, latency, and throughput achieved by VLA-MAC are higher than those achieved by some traditional approaches.

• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.265-271
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• 2005

In this study, a variable capacitive pressure sensor is fabricated for TPMS (Tire Pressure Monitoring System). This study is for developing sensors which consecutively measure the tire pressure given as 30 psi from the industrial standard. For improving non-linearity of the prior capacitive pressure sensors, it is suggested that touch mode capacitive pressure sensor be applied. In addition, initial capacitance is designed as small as possible for the conformity to the wireless sensor. ANSYS, commercial FEA package, is used for designing and simulating the sensor. The device is progressed by MEMS (Micro Electro Mechanical Systems) fabrication and packaged with PDMS. The result is obtained sensitivity, 1 pF/psi, through a pressure test. The simulation result is discrepant from experiment one. Wafer's uniformity is presumed as the main reason of discrepancy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.383-384
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• 2007