• Journal of Mechanical Science and Technology
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• v.15 no.6
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• pp.720-726
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• 2001

This paper describes a vehicle driving-load estimation method for application to vehicle Intelligent Cruise Control (ICC). Vehicle driving-load consists of aerodynamic force, rolling resistance, and gravitational force due to road slope and is unknown disturbance in a vehicle dynamic model. The vehicle driving-load has been estimated from engine and wheel speed measurements using a vehicle dynamic model a least square method. The estimated driving-load has been used in the adaptation of throttle/brake control law. The performance of the control law has been investigated via both simulation and vehicle tests. The simulation and test results show that the proposed control law can provide satisfactory vehicle-to-vehicle distance control performance for various driving situations.

• Journal of Power System Engineering
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• v.6 no.2
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• pp.73-81
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• 2002

In this study, electronically controlled automatic transmission adopted on a subcompact model in the market was modelled, and the driving performances of the transmission were simulated with the models. Kinetic and dynamic models of working components are established. The driving simulation program is developed with those models, and the various driving conditions are analyzed. With the results, the dynamic behaviour of the engine and the automatic transmission is easily understood. Especially, the transient performances of torque converter and clutches are deeply analyzed. Skipping the vehicle road test by using this analyzing tool, we can expect the cost down and the reduction of the development period of automatic transmission.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.207-213
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• 2019

The fuel-cut coast-down driving mode is activated when the acceleration pedal is released with transmission gear engaged, and it's a default function for electronic-controlled engine of vehicles. The fuel economy becomes better because fuel injection stops during fuel-cut driving mode. A fuel-cut detection method is suggested in the study and it's based on the speed, acceleration and road gradient data from GPS sensor. It detects fuel-cut driving mode by comparing calculated acceleration and realtime acceleration value. The one is estimated with driving resistance in the condition of fuel-cut driving and the other is from GPS sensor. The detection accuracy is about 80% when the method is verified with road driving data. The result is estimated with 9,600 data set of vehicle speed, acceleration, fuel consumption and road gradient from test driving on the road of 12km during 16 minutes, and the road slope is rather high. It's easy to detect fuel-cut without injector signal obtained by connecting wire. The detection error is from the fact that the variation range of speed, acceleration and road gradient data, used for road resistance force, is larger than the value of fuel consumption data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.261-264
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• 2003

In this paper, a disk-type piezoelectric transformer for the high power was investigated with the variation of road resistance. The diameter and thickness of a disk-type piezoelectric transformer was 45mm and 4mm, respectively. The piezoelectric ceramics was composed to PZT-PMN-PSN. The ratio of driving electrode and generating electrode is 2:1. The poling direction of driving part and generating part are the same. A voltage step-up ratio increased with increasing the load resistance, $R_L$, so it reached 60 under no road resistance. Also, the maximum efficiency of 97% was obtained.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1490-1492
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• 2003

A new type of piezoelectric transformer using radial vibration of disk, poled with the same direction is proposed. The piezoelectric ceramics was composed to PZT-PMN-PSN. The surface ratio of driving electrode and generating electrode of the piezoelectric transformer ranges from 1.4:1 to 3:1. As a experimental result, both resonance frequency and step-up voltage ratio increased with increasing load resistance. The step-up voltage ratio was reached more than 60 times under no load resistance. The maximum efficiency of 97.7% at load resistance of 2k${\Omega}$ was obtained.

• Journal of Biosystems Engineering
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• v.23 no.5
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• pp.445-456
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• 1998

This study was carried out to evaluate the performance of a medium scale rice polisher of 2.5 t/h and to improve its performance for producing the clean rice with high quality. The maximum internal pressure, broken rice ratio. whiteness in the rice polisher were investigated, and the effects of outlet resistance, water spraying rate, shaft revolution speed and rice moisture content on the polishing performance were analyzed to find out proper operating conditions. The conclusions of this study were as follows: 1. In the performance evaluation of the polisher, the broken rice ratio increment of 0.1%, the max. internal pressure of about 11 N/${cm}^2$, and whiteness increment of 2.2~3.7 resulted at the conditions of 20 PS driving power, 950 rpm, 150 cc/min water spraying rate, 44.1 Nㆍcm outlet resistance and about 15% rice moisture content. 2. Though max. internal pressure and whiteness at the 17% rice moisture content were higher than those at the 15% moisture content under the same operating conditions of the polisher, but the broken rice rate at the 17% moisture content was absolutely low compared with that at 15% moisture content. The water spraying effect to reduce broken rice and to increase whiteness was much significant at the 15% moisture content not significant at 17% moisture content. 3. The main parameter of the performance was outlet resistance, and low resistance of about 44.1 Nㆍcm was recommended at the polisher. 4. The proper water spraying rate in the polisher was about 150 cc/min. 5. As the shaft revolution speed decreased from 950 rpm and 800 rpm to 650 rpm, the broken rice ratio increased and whiteness decreased. 6. As the driving power of the polisher increased from 20 PS to 30 PS, the max. internal pressure decreased by about 1~2.5 N/${cm}^2$ and whiteness increased by about 1~2, but the broken rice rate was not changed. 7. The proper operating conditions of the polisher seemed to be the revolution speed of 800-950 rpm, the water spraying rate of about 150 cc/min, the oulet resistance of about 44.1 N.cm and 30 PS driving power.

• Journal of the Korea Convergence Society
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• v.5 no.2
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• pp.19-23
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• 2014

In this study, the air resistance is studied by using flow analysis near automotive body due to the its shape. Flow velocities of airs entering into inlet plane are two kinds of 70 km/h and 100 km/h. Air resistance in case of high speed driving(100 km/h) becomes higher than regular speed driving(70 km/h) and the resistance in case of the car with wider cross section at front side becomes higher than narrower cross section. By using this analysis result, the shape of automotive body can be effectively designed in order to reduce the air resistance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.718-727
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• 2000

Nowadays, most passenger cars equipped with automatic transmissions use torque converter clutches to reduce fuel consumption, and recently the slip control scheme of torque converter clutches is widely studied for the expansion of the operating region of torque converter clutches and thus for the further improvement of the fuel economy of vehicles. In this study, the analysis of the torque converter clutch system including the line pressure control unit of the automatic transmission and the actuating hydraulic control unit of the torque converter clutch is performed, and a feedforward controller and a fuzzy logic controller for its slip control are proposed. Also, for the slip controller to use the grade resistance information during control, an observer-based grade resistance estimator is designed. The performance of the designed grade resistance estimator and the slip controller is verified by dynamic simulations, and the effect of the torque converter clutch slip control on the fuel economy is examined using a driving cycle simulation.

• Journal of Drive and Control
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• v.20 no.3
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• pp.9-14
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• 2023

In this paper, the selection of a reliable accelerated life test code for a 2-ton forklift was accomplished by choosing the driving resistance coefficient failure-free test time based on a 10,000-hour B₁₀ life. The overall life and average equivalent load of the vehicle were then calculated based on actual driving test conditions using the selected driving resistance coefficient. The gear train's accelerated life test code was selected by adjusting the equivalent load to a torque and rotation speed that did not exceed 125%(about 75HP) of the vehicle rated power. The safety of the test standards was validated by conducting an actual accelerated life test utilizing the proposed test method in this study and comparing the test result with the corresponding theoretical value. It is anticipated that the reliability of the accelerated life test in this paper will be enhanced, by incorporating actual driving performance data collected directly from the forklift and adjusting the conditions used in developing the accelerated life test code.

• Journal of Biosystems Engineering
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• v.8 no.2
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• pp.11-17
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• 1983

Stress distribution under a driving lugged wheel was obtained by photoelastic method. The distribution showed two distinct parts, one part is due to sinkage and other due to compression. Results of the study are summarized as follows. 1. The tangential reactions of sinkage as well as compressing parts were directly proportional to tangential load to the driving wheel, that's appeared to be thrust of the driving wheel. The normal reactions of both sinkage and compressing parts were directly proportional to the vertical load to the driving wheel, that's appeared to be resistance against wheel motion. 2. When the tangential load was constant, changing the vertical load did not show any significant thrust variation of the driving wheel. 3. Under the condition of this experiment, the ratio of vertical load to tangential load (T.L/V.L) must be greater than 1.0 in order for the wheel to roll.