• Smart Structures and Systems
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• v.6 no.9
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• pp.1007-1023
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• 2010

This paper describes the development and evaluation of an innovative TDR distributed moisture sensor. This sensor features advantages of being responsive to the spatial variations of the soil moisture content. The geometry design of the sensor makes it rugged for field installation. Good linear calibration is obtained between the sensor measured dielectric constant and soil physical properties. Simulations by the finite element method (FEM) are conducted to assist the design of this sensor and to determine the effective sampling range. Compared with conventional types of moisture sensor, which only makes point measurement, this sensor possesses distributed moisture sensing capability. This new sensor is not only easy to install, but also measures moisture distribution with much lower cost. This new sensor holds promise to significantly improve the current field instruments. It will be a useful tool to help study the influence of a variety of moisture-related phenomena on infrastructure performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.239-243
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• 2012

This paper proposes a electric resistor sensor to measure soil moisture. The soil moisture sensor uses resistance to measure the water content of soil. The main idea is the resistance between the sensor probes can vary according to the water content of soil. Then the resistance difference can be converted to the electrical signal. This sensor is very simple and cheap. In this paper several sensors are connected in serial and composed a sensor network. This sensor network is adopted in IMS(Internet Management System) and demonstrated.

• Journal of Biosystems Engineering
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• v.13 no.3
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• pp.52-58
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• 1988

This study was conducted to develop a grain moisture content measurement sensor for automatic control of rough rice drying by natural air. For the above objective, the electrod type sensor was designed and tested. The sensor was able to produce electrical resistance which changes with moisture content of grain. An A/D converter and a micro-computer wed for processing measurement data of sensor. The developed sensor satisfied most design requirements and the results of statistical analysis show that there it no difference between the measurement method of sensor developed and of the dry-oven. Using the developed sensor and measurement system, we are able to measure moisture content of rough rice automatically in drying by natural air.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.516-519
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• 2010

In this paper, we propose to improve conventional methods, which measure moisture level in the soil and supply proper water by a hand operation. Our system use wireless sensor network between sensor node and host PC. The measurement system measure moisture level by use moisture sensor. The control system control electronic solenoid switch and supply proper water automatically.

• Journal of Biosystems Engineering
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• v.34 no.1
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• pp.15-20
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• 2009

This study was conducted to develop a moisture sensor for rapeseed, a bio-diesel material. A typical rapeseed, SUNMANG, was used as a raw material. The rapeseed moisture content sensor consists of three components, such as upper and bottom electrodes, a test material dish, and a fixing housing. To evaluate the performance, a data acquisition system was equipped with the rapeseed moisture sensor, computer, printer, and main board. The findings of this study were: 1) the rapeseed moisture content was inversely proportional to electric resistance, and 2) values of electric resistance were recorded in a range of $10{\sim}100\;M{\Omega}$, depending upon a change of the moisture content. The determination of coefficient ($R^2$) and standard error between rapeseed moisture content and electric resistance were 0.9921 and ${\pm}0.289$, which indicated a highly correlative relationship. The response of rapeseed moisture sensor to temperature change was also observed for further performance test. Satisfying results were obtained, such as the determination of coefficient ($R^2$) of 0.9918, predicted standard error of ${\pm}0.373%$, deviation of 0.103%, measurement error of $0.14{\sim}0.48%$, standard deviation of $0.01{\sim}0.22%$, and measurement time of 28.3 s per point, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.85-94
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• 1998

Due to relatively high permittivity of water in soils, we placed the soil condenser into soils to measure the soil moisture content. The soil condenser was made with two insulated iron sticks. The capacitance of the soil condenser was determined by the pulse period from RC type oscillation circuit and the highest voltage output accepting 10MHz pulse. After zero point adjustment, the measured relative capacitance percentage (RCS) to the standard condenser obtained by the oscillation circuit almost linearly correlated with the end depth of the sensor submerged in water. The RC type oscillation was disturbed by many sensor installed in a close distance in one place, presumably resulting in that the sensor sticks played as a interfering antennas generating or accepting electron waves from them. The temperature dependance of the output from the sensors could be corrected through experimentally determined revision function. Although lineal correlation was found between soil moisture and RCS, users should derive their own correlation function for every sensor to measure soil moisture, because the outputs were influenced by the installation depth and layout in the soil. The voltage type sensor responded inversely with soil moisture content and so was not suitable to the accurate measurement of soil moisture, but allows high economic benefit in various application such as simplified measurement of soil moisture and irrigation line control because of its low component count. The voltage type moisture sensor could be reinforced by relay controlling circuit to open and to close the solenoid valves respectively at optimal limits of the least and the most soil moisture according to user's adjustment.

• Structural Monitoring and Maintenance
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• v.10 no.2
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• pp.155-174
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• 2023

High performance concrete (HPC) has been extensively used in thin overlay for repair purpose due to its excellent strength and durability. This paper presents an experiment, where the sensor-instrumented HPC overlays have been followed by dynamic strain and moisture content monitoring for 1 year, under normal traffic. The vibrating wire and soil moisture sensors were embedded in overlay before construction. Four given HPC mixes (2 original mixes and their shrinkage-modified mixes) were used for overlays to contrast the strain and moisture results. A calibration method to accurately measure the moisture content for a given concrete mixture using soil moisture sensor was established. The monitoring results indicated that the modified mixes performed much better than the original mixes in shrinkage cracking control. Weather condition and concrete maturity at early age greatly affected the strain in concrete. The strain in HPC overlay was primarily in longitudinal direction, leading to transverse cracks. Additionally, the most moisture loss in concrete occurred at early age. Its rate was very dependent on weather. After one year, cracking survey was carried out by vision to verify the strain direction and no cracks observed in shrinkage modified mixes.

• Journal of Biosystems Engineering
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• v.18 no.3
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• pp.252-261
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• 1993

Nuclear magnetic resonance(NMR) was used to study a feasibility test for the possibility to develop a moisture sensor applicable for agricultural products such as raw and powdered grain. Samples of wheat flour and brown rice were tested with a 200MHz hydrogen NMR. The samples were loaded into 5mm NMR glass tubes and $30^{\circ}$ pulses were supplied to get resonance signals. Hydrogen spectrum intensities of the samples were compared to moisture content measured by a drying oven method. High linear correlations were obtained between the hydrogen spectrum intensity and moisture content. Therefore, moisure contents of agricultural products could be measured nondestructively utilizing the NMR principle. A low-cost design concept of the moisture sensor with the NMR principle was proposed for a practical use.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.415-419
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• 2021

We developed a highly accurate, yet inexpensive, refractive index (RI)-based soil moisture sensor. To detect the RI, a light guide was set with a light-emitting diode and photodiode. When the air fills the space between the soil particles, most of the incident light is reflected at the interface between the waveguide and the air because of the large RI difference. As the moisture of the soil increases, the macroscopic soil RI increases. This allows incident light to pass through the interface. The intensity of the light reaching the photodiode was simulated according to the change in the soil RI. Using the simulation results, we designed and manufactured a curved glass waveguide. We evaluated the performance of the RI-based soil sensor by comparing it with a commercially available, high-cost and high-performance time-domain reflectometer (TDR). Our sensor was 96% accurate, surpassing the costly TDR sensor.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.5-6
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• 2015

A GNSS based measurement system was constructed with not only the core sensors of a GNSS receiver, a TRS sensor and a soil moisture sensor but supplementary installation of power supply and radio communication for monitoring steep slope sites. The sensor combination extracts and transfers not only ground displacement in real-time but soil moisture content.