• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.286-292
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• 1997

Sound quality is becoming the major concern in passenger vehicle. The study on it has been done recently but it is not good enough. In order to improve the sound quality in passenger vehicle, so many noise sources must be considered and human feeling to the noise also be taken into account. In this paper, the sound quality was analyzed by vehicle road test which was carried out with varying the traveling speed. As basic factors for sound quality, only objective factors are considered such as loudness, sharpness, speech intelligibility, sound pressure level ... etc. The relations between sound pressure level and other factors are discussed from a point of view of traveling speed dependency. The frequency dependency of sound quality factor is also analyzed by frequency analysis.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.413-415
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• 2001

A railroad vehicle(Light weight electric rail car, Urban railroad, High-speed railroad) need to construct propulsion- system capacity experiment equipment to test performance or to estimate confidence. Experiment equipment in interior have been used Flywheel which is equal to the same inertia as railroad straight moment. But mechanical inertia using flywheel don't change inertia and can't embody traveling-struggle which is similar to actual traveling-struggle. We propose the method to embody electric railroad load system with inertia using electric servo motor in order to get the characteristic of real vehicle load, and confirm this algorithm with simulation and experiment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.79-85
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• 2011

Bridge Weigh-in-Motion(BWIM) system calculates a travelling vehicle's weight without interruption of traffic flow by analyzing the signals that are acquired from various sensors installed in the bridge. BWIM system or data accumulated from the BWIM system can be utilized to development of updated live load model for highway bridge design, fatigue load model for estimation of remaining life of bridges, etc. Field test with moving trucks including various load cases should be performed to guarantee successful development of precise BWIM system. In this paper, a numerical simulation technique is adopted as an alternative or supplement to the vehicle traveling test that is indispensible but expensive in time and budget. The constructed numerical model is validated by comparison experimentally measured signal with numerically generated signal. Also vehicles with various dynamic characteristics and travelling conditions are considered in numerical simulation to investigate the variation of bridge responses. Considered parameters in the numerical study are vehicle velocity, natural frequency of the vehicle, height of entry bump, and lateral position of the vehicle. By analyzing the results, it is revealed that the lateral position and natural frequency of the vehicle should be considered to increase precision of developing BWIM system. Since generation of vehicle travelling signal by the numerical simulation technique costs much less than field test, a large number of test parameters can effectively be considered to validate the developed BWIM algorithm. Also, when artificial neural network technique is applied, voluminous data set required for training and testing of the neural network can be prepared by numerical generation. Consequently, proposed numerical simulation technique may contribute to improve precision and performance of BWIM systems.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.240-247
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• 2013

Purpose: This study was conducted to develop a rubber-crawler type vehicle as a traveling device for harvesting water-dropwort cultivated in water contained paddy rice field in winter season. Methods: A commercial rubber-crawler type vehicle was used to investigate application of rubber crawler to the paddy rice field as preliminary test. As the result of the preliminary test, a both prototype traveling device with rubber crawlers for a water-dropwort harvest was designed with inclination of $45^{\circ}$ at the front-end and rear-end of crawler under the basic water depth of 0.6 m in the paddy rice field. The device was fabricated and attached to the experimental harvesting test devices on the front of the prototype vehicle. The size of the prototype crawler vehicle with a harvesting part is $2,800{\times}1,460{\times}1,040 $ (mm) ($L{\times}W{\times}H$) with weight of 9.21 kN (maximum). Sizes of the crawler of prototype vehicle are ground contact length of 900 mm, width of 180 mm, height of 1,070 mm and distance between center to center of crawlers of 720 mm. The side-overturn angle of the prototype was $26.4^{\circ}$. Results: Driving performance of the prototype vehicle in water contained paddy field were good at both forward and reverse (backward) directions as weights were applied. The drawbar pull and the maximum sinking depth of the prototype vehicle were 3.5 kN and 0.13 m respectively at water depth of 0.5 m, when the weight and bearing capacity of the prototype rubber crawler in the paddy field were 8.51 kN and 26.3 $kN/m^2$, respectively. Conclusions: Results of the driving test performance of the prototype crawler in paddy rice field at the water depth of 0.5 m were satisfactory. The prototype had enough drawbar pull and driving ability in the deep water contained paddy field.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.3
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• pp.108-115
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• 2006

In this paper, a recognition algorithm of the straight line components of lane markings and an obstacle in the travelling lane region is proposed. This algorithm also involve the pitching error correction algorithm due to traveling vehicle's fluctuation. In order to reduce their error a practical road image modelling algorithm using V.F. model and camera calibration procedure are suggested to adapt the geometric variations. It is obtained the 3D world coordinate data by the 2D road images. In experimental test, we showed that this algorithm is available to recognize lane markings and an obstacle in the traveling lane.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.104-108
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• 2008

Recently, studies conducted by our research group, revealed the possibility for reducing BSFC, NOx and PM emissions to meet the Euro 4 & 5 legislations. The main objective of the present study is to get better fuel economy in commercial vehicles by considering real driving conditions. Firstly, in order to improve fuel economy on fields, specifically it is required to analyze the driving pattern and make the representative modes from real field data. Secondly, it is performed to make the engine dynometer test to optimize the fuel consumption by reflecting on the representative driving modes, based on the Korea 2008 emission legislation equal to the Euro 4. The engine components such as engine calibration, combustion chamber, turbocharger and ancilliaries were modified to optimize vehicle fuel economy over a typical customer drive cycle whilst still meeting the exhaust emission restrictions. Finally, these results were confirmed by field testing of vehicle equipped with the updated calibration engine. It was placed the two vehicles together traveling the same route and accomplishing the same amount of stops(back to back), in order to evaluate the fuel consumption in comparison to the current vehicle. Through several repeats such as the engine calibration and field test, we could get 3 % to 7.7 % vehicle fuel economy improvements compared to previous vehicle.

• Geotechnical Engineering
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• v.13 no.2
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• pp.125-136
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• 1997

The fullsized drawbar pull test is carried out in Yeog-gol area to find out the effect of test vehicle's trafficability with the variation of density and water content at the weathered granite soils and water content at the clayey soils. According to the results, it is found that the behavior of optimum drawbar pull is effected not only by water content but also by density. This paper showed the method of determination of optimum points at a curve of drawbar pull varying with the conditons of soils. And it also showed the optimum drawbar pull coefficient and optimum slip varying with the density of the weathered granite soils.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.4
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• pp.469-479
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• 2007

This paper focuses on the capacitated vehicle routing problem that determines the routes of vehicles in such a way that each customer must be visited exactly once by one vehicle starting and terminating at the depot while the vehicle capacity and the travel time constraints must be satisfied. The objective is to minimize the total traveling cost. Due to the complexity of the problem, we suggest a tabu search algorithm that combines the features of the existing search heuristics. In particular, our algorithm incorporates the neighborhood reduction method using the proximity information of the Voronoi diagram corresponding to each problem instance. To show the performance of the Voronoi tabu search algorithm suggested in this paper, computational experiments are done on the benchmark problems and the test results are reported.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.1005-1012
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• 2005

An OHT(Over Head Transportation) vehicle is an example of the industrial monorail vehicle, and it is used in the automobile, semiconductor, LCD manufacturing industries. OHT vehicle is moved by main wheels and guide rollers. The major function of the main wheel is to support and drive the OHT vehicle. The roles of the guide roller is the inhibition of derailment and steering of the OHT vehicle. Since the required vehicle velocity becomes faster and the required load capacity is increased, the durability characteristics of the wheel and roller, which was made of urethane, need to be increased. So it is necessary to estimate the fatigue life cycle of the wheel and roller. In this study, OHT dynamic model was developed by using the multi body dynamic analysis program ADAMS. Wheel and roller are modeled by the 3-D surface contact module. Especially, motor cycle tire mechanics is used in the wheel contact model. The OHT dynamic model can analyze the dynamic characteristic of the OHT vehicle with various driving conditions. And the result was verified by a vehicle traveling test. As a result of this study, the developed model is expected to predict wheel dynamic load time history and makes a contribution to design of a new monorail vehicle.

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.111-120
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• 2007

More accurate vehicle trajectory data are now readily available through Differential Global Positioning Systems (DGPS). A variety of research opportunities emerge with utilization of such high resolution traffic data. A novel approach of this study is to explore drivers' responsive behavior to variable message signs (VMS) by using individual vehicle trajectories extracted from in-vehicle DGPS data. Responsive characteristics of drivers traveling on urban freeways, which can be represented by speeds and acceleration rates, under the provision of real-time traffic information through VMS are statistically investigated. In addition to conducting an ANOVA test, probability density functions of acceleration rates were estimated. The findings of this study can be used to understand the impact of drivers' workload when providing VMS messages on traffic flow patterns. Furthermore, results can be important fundamentals to assist in conducting more realistic traffic simulations.