• Journal of Biosystems Engineering
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• v.39 no.3
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• pp.158-165
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• 2014

Purpose: The objective of this paper was to compare test standards regarding the performance and safety of agricultural tractors to identify the differences in test conditions, measurement tolerances, and test procedures. Based on the comparison, some recommendations were proposed for possible revisions or improvements to current tractor test standards. Methods: The test standards and codes of major standards development organizations (SDOs), such as the Organization for Economic Cooperation and Development (OECD), the International Organization for Standardization (ISO), the American Society of Agricultural and Biological Engineers (ASABE), EC type approval, and the board of actions of the Nebraska Tractor Test Laboratories (NTTL), were selected and analyzed. Comparison of the test standards: The ISO provides references for fuel and lubricants for tractor tests, and the OECD provides additional measurements for calculating fuel consumption characteristics during the power take-off (PTO) tests. The ISO, EC type approval, and the ASABE provide PTO protective device and the safety requirements. During drawbar power tests, seven transmission ratios are selected for fully automatic transmissions, according to the OECD. In case of hydraulic lift tests, ISO 789-2 and OECD Code 2 advise the use of a static lift force, while SAE J283 advises the use of additional dynamic lift capacity tests for a better representation of in-field operations. The OECD, the ISO, and EC type approval determine the seat index point (SIP), whereas the ASABE determines the seat reference point (SRP) for roll-over protective structure (ROPS) tests. Diversified measurement tolerances were among the braking performance test standards. The European Union (EU) has developed daily limits for vibration exposures with adaptations from ISO 2631-1. Electromagnetic compatibility evaluations are emerging of high-efficiency tractors due to the long-term conformance to electromagnetic emissions and interferences. Comparisons of tractor test standards discussed in this paper are expected to provide useful information for tractor manufacturers and standards development personnel to improve the performance and safety test standards of tractors.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.31-39
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• 2012

On rainy days, water films form on wet road surfaces and reduce the braking force of vehicles, which often ends up in accidents. For safe driving, the road information signage provides information on road and weather conditions warning drivers of wet road conditions. Still, current information on road conditions is neither localized nor detailed but universal. The present study used the images on CCTVs installed on roads to compare the images of road surfaces in an attempt to suggest a mechanism determining factors that hamper safe driving based on the images. In the image comparison, a normal road image taken on a sunny day is used as an original image, against which road conditions occurring on rainy days are categorized and determined on a case-by-case basis to provide drivers with early warning for the sake of safe driving.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.167-173
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• 2011

This paper considers the problem of revising train departure time to reduce electric power consumption of mass rapid transit (MRT) railways. The motion of a train running between stations is divided into three phases: traction, coasting, and deceleration phases. The traction phase requires high electric power to operate MRT railways. In the coasting phase, the train moves stably by consuming little or no power. The deceleration phase is a braking mode and produces some electric power called regenerated brake power owing to inertia force for the train generated In the traction and coasting phases. The regenerative energy can be used by other accelerating trains within a specific range from the train and thereby the power consumptions of train can be reduced. We developed a mixed integer programming model to solve the problem. To validate the suggested model, a computational experiment was conducted using real data from Korea Metropolitan Subway.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1874-1881
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• 2021

Black ice, which occurs mainly on the road, vehicle traffic bridges and tunnel entrances due to the sub-zero temperature due to the slip of the road due to heavy snow, is not recognized because the image of asphalt is transmitted in the driver's view, so the vehicle loses braking power because it causes serious loss of life and property. In this paper, we propose a method to identify the black ice by using infrared camera and to identify the road condition by using deep learning to compensate for the disadvantages of existing black ice detection methods (artificial satellite imaging, checking the pattern of slip by ultrasonic reception, measuring the temperature of the road surface, and checking the difference in friction force of the tire during vehicle driving) and to reduce the size of the sensor to detect black ice.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.499-509
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• 2006

Precast concrete deck has many advantages comparing with the in-situ concrete deck, and has been successfully applied to replacement of the deteriorated decks and to the newly constructed highway bridges in domestic region. In order to apply the precast decks into the railway bridges, however, differences of the load characteristics between the highway and the railway should be properly taken into account including the train load, longitudinal force of the continuous welded rail, acceleration or braking force, temperature change and shrinkage. Proper level of the longitudinal prestress of the tendons that can ensure integrity of the transverse joints in the deck system is of a primary importance. To this aim, the longitudinal tensile stresses induced by the design loads are derived using three-dimensional finite element analyses for the frequently adopted PSC composite girder railway bridge. The effect of the temperature change is also investigated considering the design codes and theoretical equations in an in-depth manner. The estimated proper prestress level to counteract those tensile stresses is above 2.4 MPa, which is similar to the case of the highway bridges.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.183-190
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• 2015

Objective : Walking with a Material handling is an activity frequently undertaken by agricultural workers in Korea, due to the nature of their work. This study aimed to investigate differences in biomechanical variables according to the mechanical alignment of the lower limbs when walking with a heavy load, and to use this as basic data in the design of various working environments to reduce the skeletomuscular burden on the knee joint. Method : The study subjects comprised of 22 right-foot dominant adult men and women aged between 20 and 23 years. The subjects were divided into a varus or valgus group according to the mechanical alignment of the lower limb by using radiographic findings. The subjects walked without any load and with a load of 10%, 20%, or 30% of their body weight held in front of them. The Kwon3d XP program was used to calculate biomechanical variables. Results : The flexion/extension moment of the knee joint showed a decreasing trend with increased load, irrespective of the mechanical alignment of the lower limb, while the varus group did not show normal compensatory action when supported by one leg at the point of maximum vertical ground reaction force. In addition, in terms of the time taken, subjects showed no difficulties in one-foot support time up to 20%/BW, but at 30%/BW, despite individual differences, there was an increase in single limb. The increased load resulted in a decrease in the ratio of standing phase to ensure physical stability. The valgus group showed a trend of increasing the stability of their center of mass with increasing load, through higher braking power in the early standing phase. Conclusion : In conclusion, although there was no statistical difference in biomechanical variables according to the mechanical alignment of the lower limbs, the varus group showed a more irregular walking pattern with a Material handling than the valgus group, partially proving the association between lower limb alignment and walking with a Material handling.