• Journal of Biosystems Engineering
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• 제42권2호
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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.

• Journal of Information Processing Systems
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• 제15권5호
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• pp.1131-1140
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• 2019

Characteristics of fruit tree canopies are important target information for adjusting the pesticide application rate in variable rate spraying in orchards. Therefore, the target detection of the canopy characteristics is very important. In this study, a canopy volume measurement method for peach trees was presented and a variable rate spraying system based on canopy volume measurement was developed using the ultrasonic sensing, one of the most effective target detection method. Ten ultrasonic sensors and two flow control units were mounted on the orchard air-assisted sprayer. The ultrasonic sensors were used to detect the canopy diameters and the flow controls were used to modify the flow rate of the nozzles in real time. Two treatments were established: a constant application rate of $300Lha^{-1}$ was set as the control treatment for the comparison with the variable rate application at a $0.095Lm^{-3}$ canopy. The tracer deposition at different parts of peach trees and the tracer losses to the ground (between rows and within rows) were analyzed in detail under constant rate and variable rate application. The results showed that there were no significant differences between two treatments in the liquid distribution and the capability to reach the inner parts of the crop canopies.

• 농업생명과학연구
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• 제52권6호
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• pp.111-125
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• 2018

본 연구에서는 변량방제기술을 적용한 농용 회전익기를 이용하여 살포한 입자의 구간비행 상태에서의 거리별 살포 패턴을 측정함으로써 무인 항공방제의 농약 부착률과 입자경의 분포 균일도를 평가하였다. 비행을 등속으로 유지하는 안내비행과 자동비행 모드에서 유효살포폭 3.6m로 인접비행 구간과 살포폭이 일부 중첩된 피복률에 대한 가로방향 분포의 변이계수는 30% 정도를 보였고, 비행방향 진로위치에 대한 피복률의 변이계수는 10% 미만으로 매우 균등한 것으로 평가되었다. 따라서 살포작업시 기체의 지면속도(ground speed)의 변이를 보상하는 변량살포기술은 균일도 측면에서 우수한 것으로 판명되었으며, 또한 입자경의 분포에 있어서 체적중위직경(VMD)과 개체중위직경(NMD) 모두 항공방제에 적절한 크기와 균일한 분포를 보였다. 따라서 농용 회전익기를 이용하여 소필지의 항공방제작업을 무인화 하는데 있어, 변량방제장치를 적용함으로써 소규모 필지의 균일 정밀방제를 도모하고자 하였다.

• Journal of Biosystems Engineering
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• 제35권2호
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• pp.132-137
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• 2010

Site-specific N application for corn is one of the precision crop management. To implement the site-specific N application, various nitrogen stress sensing methods, including aerial image, tissue analysis, soil sampling analysis, and SPAD meter readings, have been used. Use of side-dressing, an efficient nitrogen application method than a uniform application in either late fall or early spring, relies mainly on the capability of nitrogen deficiency detection. This paper presents map-based variable rate nitrogen application based using a multi-spectral corn nitrogen deficiency(CND) sensor. This sensor assess the nitrogen stress by means of the estimated SPAD reading calculated from the corn leave reflectance. The estimated SPAD value from the CND sensor system and location information form DGPS of each field block was combined into the field map using a ArcView program. Then this map was converted into a raster file for a map-based variable rate application software. The relative SPAD (RSPAD = SPAD over reference SPAD) was investigated 2 weeks after the treatments. The results showed that the map-based variable rate application system was feasible.

• Journal of Biosystems Engineering
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• 제32권6호
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• pp.383-388
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• 2007

In precision farming, proper calibration and operation of a variable rate machine are critical to reduce input of agrochemicals and to ensure productivity and quality of agricultural products. As an effort to introduce precision farming to rice production in Korea, a pneumatic granular applicator was developed. This investigation intended to evaluate the application performance such as application accuracy, application uniformity and to suggest how to adjust the blow-heads to get uniform application pattern, and to suggest a practical way of adjustment of the blow-heads for uniform application. Tests to evaluate the application performance were conducted. The application uniformities (CV) in both transverse direction and longitudinal direction were less than 15% and application accuracy was greater than 81%. A simple method for adjusting the inserting length of blow-heads was suggested.

• Journal of Biosystems Engineering
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• 제36권1호
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• pp.15-22
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• 2011

An experimental variable rate nursery sprayer was developed to adjust application rates for canopy volume in real time. The sprayer consisted of two vertical booms integrated with ultrasonic sensors, and variable rate nozzles coupled with pulse width modulation (PMW) based solenoid valves. A custom-designed microcontroller instructed the sensors to detect canopy size and occurrence and then controlled nozzles to achieve variable application rates. A spray delivery system, which consisted of diaphragm pump, pressure regulator and 4-cycle gasoline engine, offered the spray discharge function. Spray delay time, time adjustment in spray trigger for the leading distance of the sensor, was measured with a high-speed camera, and it was from 50 to 140 ms earlier than the desired time (398 ms) at 3.2 km/h under indoor conditions. Consequently, the sprayer triggered 4.5 to 12.5 cm prior to detected targets. Duty cycles of the sprayer were from 20 to 34 ms for senor-to-canopy (STC) distance from 0.30 to 0.76 m. Outdoor test confirmed that the nozzles were triggered from 290 to 380 ms after detecting tree canopy at 3.2 km/h. The spray rate of the new sprayer was 58.4 to 85.2% of the constant application rate (935 L/ha). Spray coverage was collected at four areas of evergreen canopy by water sensitive papers (WSP), and ranged from 1.9 to 41.1% and 1.8 to 34.7% for variable and constant rate applications, respectively. One WSP area had significant (P < 0.05) difference in mean spray coverage between two application conditions.

• Journal of Biosystems Engineering
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• 제31권6호
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• pp.474-481
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• 2006

In this paper, a new type blow head was developed and pneumatic application system was evaluated. The blow head had one operating factor, inserting length of collecting plate, that was directly related to discharge rate and application pattern. To determine Proper blow head arrangement and application height, a blow head set was tested. Three-way ANOVA was conducted to investigate relationships between CV value, the discharge rate and inserting length of collecting plate. The discharge rate and inserting length of collecting plate were statistically significant at p=0.01, affecting uniformity of application pattern. The best CV value among the application tests was 23.3% when the application rate and application height was 23.5 g/sec and 80 cm respectively. The worst CV value was 63.3% in 111.4 g/sec. Therefore, it is necessary to increase number of blow head in a section of the boom in improve application uniformity.

• Journal of Biosystems Engineering
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• 제31권6호
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• pp.482-488
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• 2006

Application of precision farming technology to rice cultivation could be an effective measure for rice quality improvement and environment-friendly agriculture. This study was conducted to develope a variable rate pneumatic granule applicator. Previous study reported that application uniformity of the prototype machine (C.V. = 23.3%) was not satisfactory. To improve the uniformity, increase of blow-head number from 12 to 16 was suggested. Analysis of the pneumatic conveying system showed that increase of number of blow-head was possible. Three-way variance analysis of the modified applicator showed that inserting length should be changed according to granule metering rate. The range of metering rate from 27.3 to 417.9 g/s were divided into 4 levels and 4 sets of inserting lengths were determined to ensure CV values less than 15%. The revised applicator showed satisfactory C.V. values of 9.4 to 14.6% in the metering rate. Granule conveying pattern was observed using a high speed camera and judged as the homogeneous flow pattern.

• 한국토양비료학회지
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• 제38권4호
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• pp.202-210
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• 2005

정밀 농업 시행에 있어서 포장 변이성에 대한 이해가 필수적이므로, 직파 재배 논에서 포장 변이성 조사와 토양 검정 결과에 다른 질소 변량 시비에 대한 현장 시험이 전북 김제의 직파 재배 논 시험 포장과 농가 시범 포장에서 이루어졌다. $35m{\times}112m$ 단위 포장에서 10 m 간격의 방격형으로 표토의 토양 시료를 채취하여 분석하였다. 토양 유기물, 유효 인산 및 규산, 그리고 치환성 칼륨 등에 대한 분석이 이루어졌다. 시험 포장에 대한 토양 검정 결과에 의해 다수확과 저투입 농업을 위한 질소 시비 추천량을 계산하여 그 분포도를 작성하였다. 2001년과 2002년의 시험 포장에서의 질소 변량 시험을 토대로, 2003년에는 농가 포장 3개를 선정하여 저투입 질소 시비량을 기준으로 질소 변량 시비에 대한 농가 실증 시험을 하였고, 경제성을 분석하였다. 변량 시비에 의해 수량 중가 및 수량 변이 감소 효과를 알 수 있었다. 변량 시비에 의한 수량 증가와 시비량 절감에도 불구하고, 토양 검정에 소요되는 비용이 절감 비용을 초과하였다.

• Journal of Biosystems Engineering
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• 제31권2호
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• pp.108-114
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• 2006

This study was conducted to design and fabricate a controller for variable-rate application of granular fertilizer based on physical and chemical information, to analyze the performance of the controller and characteristics of a discharger. The result of the study are summarized as follows: 1. The charge ratios of discharger by accumulation heights of fertilizer in hopper were examined, and the variations in charge ratio were $72.58{\sim}93.33%$ and $63.14{\sim}94.42%$ for the fertilizers Super 21 and Sinsedae, respectively. The charge ratio also decreased as the rotational speed of discharger increased. 2. The coefficient of variation of discharge amount by rotational speed and discharge time of discharger were in the range of $2.94{\sim}11.23%$ and $2.82{\sim}10.80%$ for the fertilizer of Super 21 and Sinsedae. Except the rotational speed of 12 rpm, the coefficient of variation for discharge amount were relatively small with 4% more or less 3. In order to evaluate the rotational speed of discharger, the control signal in the range of $0{\sim}5V$ was subdivided into the 50 steps by 0.1V. The regression equation for the rotational speed of discharger was Y=55.984X-79.174(X: input voltage, V, Y: discharger speed, RPM) and the $R^2$ was 0.99. 4. In order to evaluate the performance of the controller for variable-rate application of granular fertilizer, settling time to unit step input was examined. The settling time varied from 0.8sec to 1.4 sec.