• Journal of Biosystems Engineering
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• 제35권4호
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• pp.231-238
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• 2010

The purpose of this paper was to investigate experimentally the steering torque characteristics of a tractor operated in various ground conditions. The experiments were conducted with the tractor reconstructed for steering torque test of the tractor at two different off-road conditions (ground-I and ground-II) and a on-road condition (ground-III), three different levels of tire inflation pressures (69 kPa, 138 kPa and 207 kPa), and four different levels of axle loads (4120 N, 4730 N, 5340 N and 5950 N). The results of this study are summarized as follows: 1) The steering torque was increased with the increase in steering angle for all experimental levels of ground conditions, axle loads and inflation pressures of tire. 2) As the axle load increased, the steering torque of the tractor increased for all ground conditions, and the increasing rate of the steering torque with the increase of axle load was greater at on-road than at off-road. 3) As the tire inflation pressure decreased, the steering torque increased. Also the increasing tendency of the steering torque with decreasing the tire inflation pressure showed that the harder the ground was, the larger the effect was. But for the soft ground condition, ground-I, no specific trend with inflation pressures was found. 4) Steering angle-steering torque relationship with ground conditions showed that the increasing rate of the steering torque was greater at on-road than off-road for small steering angle under 10 degree, and was greater at off-road than on-road for large steering angles over 10 degree.

• Journal of Biosystems Engineering
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• 제29권5호
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• pp.419-424
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• 2004

In this study, a series of soil bin experiment was carried out to investigate experimentally the effect of the tire inflation pressure and axle load of tire on the steering torque for the off-road condition. The experiment was performed at the three levels of off-road conditions(ground I, ground II and ground III) and on-road condition(ground IV), four levels of tire inflation pressure(120 kPa, 170 kPa, 220 kPa and 270 kPa), and four levels of axle load(1470N, 1960N, 2450N and 2940N). The results of this study are summarized as follows: 1. Steering torque at the off-road conditions were higher than that on the on-road conditions for all levels of tire inflation pressure and axle load. 2. As the axle load increased, steering torque also increased f3r all experimental ground conditions. 3. For the axle load of 1470N the biggest steering torque was measured on the ground condition I, but as the axle load increased to the value of 2940N the biggest steering torque was measured on the ground condition III. From the above results, it was found that for the low axle load, steering torque gets higher on the soft ground condition, but for the high axle load, steering torque gets higher on hard ground condition for whole range of experimental conditions. 4. As the tire inflation pressure decreased, steering torque increased on the on-road condition, but no specific trend was not found at the off-road conditions.

• 한국지반공학회논문집
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• 제34권9호
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• pp.33-42
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• 2018

야지궤도차량 구동 시 무한궤도를 통해 전달된 엔진출력은 지반-궤도 접지면에서 지반을 전단시켜 슬립변위 및 지반추력을 발현시킨다. 이때 지반추력의 반력이 야지궤도차량의 구동력으로 작용하는데, 지반이 연약하여 구동에 필요한 지반추력을 확보하기 어려운 경우에는 무한궤도 표면에 그라우저를 부착하여 구동성능을 개선시킨다. 본 연구는 그라우저 효과를 적절히 고려하여 야지궤도차량의 지반추력을 평가하기 위한 기초연구로서 수행되었다. 우선 지반-궤도 접지면의 전단메커니즘을 바탕으로 그라우저가 부착된 야지궤도차량의 지반추력을 평가하기 위한 방법을 새로이 제안하였다. 이를 통해 그라우저가 야지궤도차량의 구동성능에 미치는 영향을 평가한 결과, 그라우저가 부착됨에 따라 야지궤도차량의 전체지반추력이 증가하여 구동성능이 개선되는 것을 확인하였다. 특히, 그라우저의 길이가 증가하고 간격이 가까울수록 전체지반추력 증가효과가 명확해지는 것으로 나타나, 그라우저 형상비(=간격/길이)가 작을수록 야지궤도차량의 구동성능을 더욱 크게 개선시킬 수 있을 것이라 판단된다.

• Journal of Biosystems Engineering
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• 제31권2호
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• pp.81-87
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• 2006

In this study, a mathematical model was suggested to predict the maximum steering torque of a tractor on off-road. The model took into account the characteristics of soil, including the pressure-sinkage and the shearing characteristics as well as the primary design parameters of steering system of the tractor. The efficiency of the developed model was verified via comparison of the maximum steering torque predicted using the model with those measured from steering torque test. The results showed that the predicted maximum steering torques were in good agreement with the measured ones from the steering test on soft soil in which tractor is generally operated. Thus, we concluded that the model developed in this study could be used for prediction of maximum steering torque of a tractor.

• 한국연소학회지
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• 제21권3호
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• pp.32-38
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• 2016

This paper aims to predict oxidation amounts of catalyst and heat produced through passive regeneration on DPF according to different EGR rates and loads of off-road engines. Soot oxidation model and parameter assumption model were used for the test. Engine data were measureed with 25%, 50% and 75% of 1600 RPM loads and with 0% and 30% of EGR rates in order to estimate parameters. Oxygen levels calculated on the DPF downstream and oxygen levels measured were compared through all of the experimental conditions for validating the model. Oxidation rates on DPF according to different EGR rates and oxygen levels on the DPF downstream were estimateed successfully, which can be applied for off-road vehicles.

• Journal of Biosystems Engineering
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• 제27권6호
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• pp.501-512
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• 2002

Traction performance of off-road vehicles is estimated using slip-traction relationships Two zero condition accepted by ASAE have been used widely to obtain the slip-traction relationships of off-road vehicles. This study was carried out using the soil bin systems to investigate the characteristic of slip-traction curves obtained using two zero conditions defined by ASAE. which are driving and driven zero condition, and to present disadvantage of slip-traction relationship based on two zero conditions of ASAE. The results of this study are summarized as follows : 1. For the driving zero condition, the curve of slip-traction relationship shows some issues. The first question is that the slip is zero when the traction is zero. The second question is that the value of slip is smaller than that of corresponding real slip, as the rolling radius decreased f3r the setting zero condition with driving wheel. 2. For the driven zero condition. slip occurs when the traction is zero, which is more realistic results than driving zero condition. But when a zero condition is set, skid occurs and this result increased the rolling radius of tire and increased slip value f3r the specific traction value of whole slip range. This kind of trend was getting bigger as the soil is softer, or the tire inflation pressure is higher. 3. From the results of this study, it was found that slip-traction relationship obtained by two zero conditions of ASAE is not realistic in estimating the traction performance of off-road vehicles. And also slip-traction relationship obtained for the same experimental condition showed different result in accordance with chosen zero condition,

• 대한토목학회논문집
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• 제36권2호
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• pp.277-283
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• 2016

최근 국내외에서 3차원 설계 및 건설정보모델링(BIM, Building Information Modeling)에 대한 관심이 증가하고 토목 구조물의 3차원 설계와 물량 산출 방법에 대한 연구가 진행되고 있다. 그러나 도로나 철도의 교량 및 터널과 같은 구조물 중심의 설계 및 물량 산출에 대한 연구는 많이 진행되고 있지만 토공이 중심인 공정에 대한 물량 산출 방안 및 그 결과에 대한 연구는 부족한 실정이다. 따라서 본 연구에서는 원 지표면과 최종 토공면을 불규칙한 경우와 일정한 경사를 가진 경우로 구분하여, 3차원 설계를 진행하였다. 3차원 설계 및 물량 산출 결과 2차원 설계에서 적용되는 양단면 평균법에 대하여 복합토량법이 최대 5%정도 오차가 발생하는 것으로 나타나 3차원 설계에 대한 물량 산출방법 적용시 주의가 필요하며, 산출 결과와 함께 산출 방법도 같이 명기되어야 할 필요가 있는 것으로 나타났다.

• 대한교통학회지
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• 제26권4호
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• pp.7-16
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• 2008

서울시 도시고속도로 진출부에 극심한 정체가 다수 발생하고 있는데, 이러한 진출부 정체의 주원인으로 진출램프 하류부교차로의 처리용량 부족, 비효율적인 신호운영 등이 지적되고 있다. 이에 하류부교차로의 설계 및 운영 개선을 통한 진출램프 하류부 교차로의 혼잡 관리가 필요하다. 본 연구에서는 도시고속도로 진출램프 하류부교차로의 개선 사례인 중동 IC를 중심으로 분석하였다. 고속도로와 간선도로가 교차 시 다이아몬드 IC가 주로 사용되고 양자택일로 SPUI가 사용되는데, 이 다이아몬드 IC와 SPUI의 운영을 중동 IC에 적용해 시뮬레이션 등으로 분석하여 그 효율성을 비교하였다. 분석 결과 다이아몬드 IC로 운영 시 4 phase with overlaps 적용 등의 신호운영 개선으로 진출부 혼잡 개선이 가능하고, frontage road가 없는 경우 SPUI가 다이아몬드 IC보다 더 효과적일 수 있으나 frontage road가 있으면 다이아몬드 IC가 SPUI보다 더 효율적인 것으로 나타났다. 본 연구 결과를 토대로 진출램프 하류부교차로의 효율적인 운영을 통해 하류부교차로 뿐만 아니라 도시고속도로 본선의 혼잡을 최소화할 수 있을 것으로 기대된다.

• 한국자동차공학회논문집
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• 제8권5호
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• pp.188-195
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• 2000

This study was conducted to develop the mathematical model and the computer simulation program(TPPMWV) for predicting the tractive performance of off-road wheeled vehicles operated on various soil conditions. The model takes into account main design parameters of a wheeled vehicle, including the radius and width of front and rear tires, the weight of vehicle, wheelbase and driving type(4WD, 2WD). Soil characteristics, such as the peressure-sinkage and shearing characteristics and the response to repetitive loading, are also taken into consideration. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMWV with measured ones obtained by field tests for two different driving types of wheeled vehicle. As a results, the drawbar pulls predicted by the TPPMWV were well matched to the measured ones within the absolute errors of 5.25%(4WD) AND 9.42%(2WD)for two different driving types, respectively.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.351-357
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• 2005

Development of a real-time simulation model for high-speed and multibody tracked vehicles is difficult because they involve hundreds of highly nonlinear equations. In the development of a reliable tracked vehicle model for real-time simulation, it is helpful to use an off-line tracked vehicle model developed by considering all the degrees of freedom of each element. This paper presents a step-by-step procedure for the development of a real-time simulation model based on the off-line tracked vehicle model. The road input data, Profile IV, is used for the real time simulation and simulation results are compared with vehicle test results obtained in the military test field. It is noted that the simulation results are quite close to the test results.