• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.239-243
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• 2012

본 논문에서는 전기 저항식 수분 측정 방식을 선택한 토양수분센서를 제안하였다. 이 방식은 토양내의 수분량에 따라 저항의 변화가 생기는 것을 전기적인 신호로 변환하여 토양수분량과의 관계를 비교하여 수분량을 측정하는 방식으로 방법이 간단하며 저렴한 비용으로 간단하게 장치를 구현하였으며, 시리얼통신을 이용하여 여러 개의 센서를 하나의 네트워크에 묶어 사용하였다. 이 센서 네트워크를 사용하여 IMS(Internet Management System)에 적용하였으며, 센서 네트워크가 웹에서도 잘 작동함을 보였다.

• Smart Structures and Systems
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• 제6권9호
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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.

• 한국토양비료학회지
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• 제31권2호
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• pp.85-94
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• 1998

물의 높은 유전율을 이용하여 토양 수분함량을 검정하고저 피복 절연 철봉을 토양에 박아 두 극으로 하는 토양 매질 콘덴서에 RC발진회로를 적용하여 주기를 조사하거나 또는 10 mega Herz Pulse 투여시 최대 저장(貯藏) 전압을 검정하는 방식으로 수분 변화에 따른 토양의 유전율을 조사하였다. 주기식 쎈서에선 토양 콘덴서의 용량이 영점 조정후 표준 콘덴서에 비교된 백분율로 출력되었는데 쎈서봉을 물에 담근 깊이와 선형적 관계에 있었다. 여러 개의 쎈서를 가까운 거리에 설치하면 쎈서봉이 안테나 역할을 하여 RC 발진에 교란이 있었으며 변온에 따른 출력 보정 함수를 제시했다. 토양 수분 함량과 출력사이에 높은 상관성이 있으나 쎈서 붕이 설치된 깊이 및 방향에 따라 출력반응이 변화하므로 사용자가 설치후 출력을 토양수분으로 변환하는 함수를 구하여야 한다. 전압식 쎈서에선 출력이 토양수분 함량과 역함수적 관계에 있어 토양 수분 정밀 계측용으론 적합치 않으나 구성 부품이 적고 노화가 느리어 토양 수분의 간이 검정에 적합하고 출력 전압에 따라 relay를 개폐하되 개폐 전압을 사용자가 설정할 수 있는 회로를 첨부하여 수위 조절 또는 토양수분에 따른 관개 line개폐에 활용한 결과 재현성이 우수하였다.

• 센서학회지
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• 제30권6호
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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.

• 한국토양비료학회지
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• 제44권3호
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• pp.331-336
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• 2011

최근 편리함과 측정의 정확성으로 인해 Capacitance sensor가 토양수분 연구나 물관리에 국제적으로도 널리 이용되고 있다. 이 연구는 Capacitance sensor (EnviroSCAN, Sentek Ltd.)가 화산회토양이 많이 분포하는 제주도 지역에서도 활용성이 있는 지를 알아보기 위해 유기물함량이 다른 제주도의 대표적인 토양 종류를 이용하여 Calibration 시험을 수행하였다. 시험 결과 화산회토양에서는 비화산회토양과 달리 센서의 Scaled frequency와 토양의 용적수분함량 간에 Calibration식이 로그식 형태로 나타내는 것이 일반적으로 적용되는 지수식 형태로 나타내는 것보다 상관이 더 높게 나타났다. 또한 화산회토양이 많이 분포하는 지역에 서는 토양수분함량이 높아 습하거나 매우 적어 건조할 경우에는 Capacitance sensor에 의한 수분함량 측정값이 건조기를 이용한 수분함량 값보다 과소하게 측정될 수 있었다. Capacitance sensor를 이용하여 화산회토양에서 토양 수분함량을 정확하게 측정하기 위해서 Calibration식에 적용될 수 있는 현실적인 계수값을 제시하였다. 또 현재 이용되는 EnviroSCAN capacitance probes의 활용성을 제고하기 위해서 계수값을 유기물함량별로 추정하는 식을 제시 하였다. Capacitance sensor를 이용하여 토양수분함량을 정확하게 측정하기 위해서는 사전에 토양의 공극분포, 유기물함량, EC 등 측정여건을 파악하여 조절하는 것이 필요하였다.

• Structural Monitoring and Maintenance
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• 제10권2호
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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.

• 지질공학
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• 제18권3호
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• pp.311-319
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• 2008

주파수 인피던스를 이용하는 ThetaProbe ML2x인 ADR 형식의 토양함수비센서를 적용하여 주문진 표준사, 상주 화강 풍화토, 장수 편마암풍화토을 대상으로 실험을 수행하였다. 시험의 목적은 측정센서의 측정 정밀도를 측정로드부 삽입 깊이에 따른 변화 양상을 파악하였다. 흙매질은 체적함수비 함량과의 관계를 비교하기 위하여 건조상태와 습윤상태로 구분하여 수행하였다. 측정결과에서 측정로드부가 흙매질 내 5cm 이상 삽입되면 측정전압의 변화폭이 크게 감소하는 것을 파악하였다. 또한, 표준사와 같이 균질한 입자를 가진 흙보다는 점토와 실트 등과 같은 세립질을 함유한 화강풍화토와 편마암풍화토에서 측정전압이 안정적인 형태를 갖는 것으로 나타났다. 따라서, 측정치는 측정로드부가 다공질매질과의 접촉 면적이 커질수록 안정적인 값을 제공한다.

• 한국농공학회논문집
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• 제62권6호
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• pp.11-20
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• 2020

We estimated the spatio-temporally distributed soil moisture using Sentinel-1A/B SAR (Synthetic Aperture Radar) sensor images and soil moisture data assimilation technique in South Korea. Soil moisture data assimilation technique can extract the hydraulic parameters of soils using observed soil moisture and GA (Genetic Algorithm). The SWAP (Soil Water Atmosphere Plant) model associated with a soil moisture assimilation technique simulates the soil moisture using the soil hydraulic parameters and meteorological data as input data. The soil moisture based on Sentinel-1A/B was validated and evaluated using the pearson correlation and RMSE (Root Mean Square Error) analysis between estimated soil moisture and TDR soil moisture. The soil moisture data assimilation technique derived the soil hydraulic parameters using Sentinel-1A/B based soil moisture images, ASOS (Automated Synoptic Observing System) weather data and TRMM (Tropical Rainfall Measuring Mission)/GPM (Global Precipitation Measurement) rainfall data. The derived soil hydrological parameters as the input data to SWAP were used to simulate the daily soil moisture values at the spatial domain from 2001 to 2018 using the TRMM/GPM satellite rainfall data. Overall, the simulated soil moisture estimates matched well with the TDR measurements and Sentinel-1A/B based soil moisture under various land surface conditions (bare soil, crop, forest, and urban).

• Water Engineering Research
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• 제3권1호
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• pp.31-44
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• 2002

The effect of diurnal cycle, intermittent visit of observation satellite, sensor installation, partial coverage of remote sensing, heterogeneity of soil properties and precipitation to the soil moisture estimation error were analyzed to present the global sampling strategy of soil moisture. Three models, the theoretical soil moisture model, WGR model proposed Waymire of at. (1984) to generate rainfall, and Turning Band Method to generate two dimensional soil porosity, active soil depth and loss coefficient field were used to construct sufficient two-dimensional soil moisture data based on different scenarios. The sampling error is dominated by sampling interval and design scheme. The effect of heterogeneity of soil properties and rainfall to sampling error is smaller than that of temporal gap and spatial gap. Selecting a small sampling interval can dramatically reduce the sampling error generated by other factors such as heterogeneity of rainfall, soil properties, topography, and climatic conditions. If the annual mean of coverage portion is about 90%, the effect of partial coverage to sampling error can be disregarded. The water retention capacity of fields is very important in the sampling error. The smaller the water retention capacity of the field (small soil porosity and thin active soil depth), the greater the sampling error. These results indicate that the sampling error is very sensitive to water retention capacity. Block random installation gets more accurate data than random installation of soil moisture gages. The Walnut Gulch soil moisture data show that the diurnal variation of soil moisture causes sampling error between 1 and 4 % in daily estimation.

• 한국자원식물학회지
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• 제34권6호
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• pp.608-615
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• 2021

Soil moisture control system including soil sensing and automatic water supply chain was constructed on open farmland and pot conditions. Soil moisture was controlled by the system showing over the soil moisture contents except 40% treatment. EC was gradually decreased by increasing cultivation days. On applying this system to control soil moisture, the growth and development characters of the bellflower were improved compared with control, cultivation without the automatic irrigation. Of the growth and development characters, plant height with water treatments was higher than that of control in 1st-year plants. Moreover, numbers of branch were increased by the increased soil moisture on farmland and pot condition. Capsule numbers for seed were best at 20%, 30% soil moisture treatment in 1st-year plants, and 20% to 50% treatment in 2nd-year plants. The construction of automatic soil moisture control system provide fundamental data for plant growth and development on open farmland soil condition.