• Journal of Biosystems Engineering
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• 제30권2호
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• pp.127-133
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• 2005

Precision tillage is designed to till lands variably according to their firmness. Therefore, it is necessary to measure soil firmness in fields and present it in a form with which the variable tillage on be performed. Such forms may be classified into two categories: sensor-based and map-based forms. The map-based approach appears to be inevitable until the technology develops high enough to secure the sensor-based approaches. The first step for map-based precision tillage may be to develop a tillage recommendation map. In this study, a tractor-mountable automatic soil firmness measurement system was developed to construct a cone index map. The system is comprised of three ASAE Standard cone penetrometers and a hydraulic unit for controlling operation of the penetrometers. The system is designed to conduct stop-and-go measurements in fields. The measurements from the three penetrometers are transferred to a microcomputer and the average cone index was calculated. This average cone index was taken as soil firmness of the location where the measurement was made. The cone indices thus determined were used to construct a cone index map using the ArcView software. The system also displays the soil penetration resistance, cone index and soil depth as the cone penetrates into the soil. The field performance of the system was evaluated and the cone index maps at different depths were also presented.

• Journal of Biosystems Engineering
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• 제41권4호
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• pp.304-312
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• 2016

Purpose: Soil strength has been measured using a cone penetrometer, which is making it difficult to obtain the spatial data required for precision agriculture. Our objectives were to evaluate real-time horizontal soil strength (RHSS) to measure soil strength in real time while moving across the field. Using the RHSS data, the tillage depth was determined, and the power consumption of a tractor and rotavators were compared. Methods: The horizontal soil-strength index (HSSI) obtained by the RHSS was compared with the cone index (CI), which was measured using a cone penetrometer. Comparison analysis in accordance with the measurement depth that increased at 5-cm interval was conducted using kriged maps at six sensing depths. For tillage control and evaluation of the power consumption, the system was installed with a potentiometer for tillage depth, a torque sensor from the rear axle, and a power take-off (PTO) shaft. Results: The HSSI was lower than the CI, but they were the same at 54.81% of the total grids for the 5-cm depth and at 3.85% for the 10-cm depth. In accordance with the recommended tillage map, tillage operations between 0 and 15 cm left 2.3% and 7% residue cover on the soil, and that between 20 and 10 cm covered a wider utilization of 3% and 18.4%, respectively. When the tillage depth was 15 cm, the comparison result of the power requirements between the PTO and rear axle in terms of control performance revealed that the maximum power requirements of the axle and PTO were 44.63 and 23.24 kW, respectively. Conclusions: An HSSI measurement system was evaluated by comparison with the conventional soil strength measurement system (CI) and applied to a tractor to compare the tillage power consumption. Further study is needed on its application to various farm works using a tractor for precision agriculture.

• 터널과지하공간
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• 제28권4호
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• pp.343-357
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• 2018

절리군 대표방향성에만 의존하는 기존의 평사투영 사면해석의 불확실성을 극복하고 해석결과의 신뢰성을 증진시키기 위하여 확률통계학적으로 도출된 절리극점들의 dense point 및 절리군 대표방향성과 암반구조 분석결과를 종합적으로 고려하여 사면거동양상을 분석하는 알고리즘을 고안하였다. 이를 위하여 절리극점들의 분포양상에 의거하여 절리확산지수를 산정하는 기법을 고안하였으며, 콘각에 따라 상이하게 도출되는 절리확산지수 및 절리군 수효와 방향성을 종합적으로 고려하여 사면해석에 사용될 대표방향성을 추출하였다. 이들 대표방향성을 평사투영분석에 활용하여 신뢰성이 증진된 사면해석을 수행할 수 있었다. 또한 평면파괴가 우려되는 사면에 대해 한계평형이론에 의거하여 민감도 해석을 수행하고, 사면 안정성에 대한 절리강도 및 외부하중 변화의 영향을 심도 있게 분석하였다.

• 한국지반공학회논문집
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• 제38권1호
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• pp.5-15
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• 2022

지난 2017년 포항 지진에 의해 액상화가 관측됨에 따라 액상화 피해를 예측하는 연구수요가 높아지고 있다. 액상화 현상은 지반이 전단 강도를 상실하는 현상을 말하며 상부 구조물이 가라앉는 피해가 발생하게 된다. 이에 대한 대비책으로써 액상화 가능지수(Liquefaction Potential Index, LPI)를 활용하여 액상화 피해 규모를 파악하는 연구가 수행되어 왔으나 국내의 연구 사례 또한 충분하지 못한 실정이다. 이에 따라 본 연구에서는 공간보간 대상에 따른 액상화 재해도 및 액상화 가능지수를 결정하는 지반정보에 따른 액상화 재해도를 작성하고 각 재해도의 정밀도를 비교하여 액상화 재해도의 정밀도를 향상시키는 방안을 제안하고자 하였다. 그 결과, 공간보간의 대상을 LPI 결정에 활용되는 지반정보로 하는 것이 LPI값 자체를 공간보간 하는 경우에 비해 높은 정밀도를 보이는 것으로 나타났다.