• International journal of advanced smart convergence
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• v.12 no.4
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• pp.443-450
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• 2023

One of the basic tasks in the automobile manufacturing process is to design a bare chassis, which is the basic frame of a vehicle, and a bracket is a member connecting various devices to the frame. Bracket, which is a member connecting the engine, transmission, and suspension, which are the core devices of driving and operating the vehicle, to the frame, must maintain safety during vehicle operation. If the bracket connecting the various devices constituting the vehicle to the frame does not have durability, serious accidents may occur during operation of the vehicle. In this study, we performed stress analysis on the brackets installed in the bare chassis of the 25-passenger bus in the development stage. Based on the stress analysis performed, an improved bracket dimension was proposed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.1
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• pp.1-15
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• 2016

This study aims to develop a model by which city bus drivers who are likely to cause an accident can be figured out based on the information about their actual driving records. For this purpose, from the information about the actual driving records of the drivers who have caused an accident and those who have not caused any, significance variables related to traffic accidents are drawn, and the accuracy between models is compared for the classification models developed, applying a discriminant analysis and logistic regression analysis. In addition, the developed models are applied to the data on other drivers' driving records to verify the accuracy of the models. As a result of developing a model for the classification of drivers who are likely to cause an accident, when deceleration ($X_{deceleration}$) and acceleration to the right ($Y_{right}$) are simultaneously in action, this variable was drawn as the optimal factor variable of the classification of drivers who had caused an accident, and the prediction model by discriminant analysis classified drivers who had caused an accident at a rate up to 62.8%, and the prediction model by logistic regression analysis could classify those who had caused an accident at a rate up to 76.7%. In addition, as a result of the verification of model predictive power of the models showed an accuracy rate of 84.1%.

• Physical Therapy Korea
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• v.4 no.2
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• pp.18-35
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• 1997

The purpose of this study were to determine causes of low back pain in bus drivers who usually work in prolonged sitting position and to find the relationship of back pain with general characteristics and work environmental characteristics, stress symptoms, to com맹re lordosis angle of habitual driving posture and resting posture in low back pain group and non-low back pain group, and to use this result as a basis for improvement of work environment and comprehensive rehabilitative management of low back pain. Ninety-eight bus drivers were selected from the membership of an urban transit union in Seoul. These informations were collected from May 1, 1997 to May 25, 1997 by means of structured questionnaires and X-ray findings. These data were analyzed by $x^2$ test, t-test, logistic regression using SAS. The major results were as follows: 1. Of the respondents, 66.3% of bus drivers were found to be experiencing back pain. 2. Of the respondents of low back pain groups, 78.5% reported that major cause of low back pain was due to prolonged sitting. 3. The group with experiences of frequent or continuous vibration had more low back pain (p<0.05). There were no significant differences among other work environmental factors. 4. Average stress score was significantly higher in the group with low back pain than in the group without low back pain (p<0.05). 5. The results of the logistic regression analyses were statistically significant vibration from seat and stress score among the risk factors (p<0.05). 6. Averaged lordosis angle of habitual driving posture was $7.6{\pm}14.9$ degrees in low back pain group, $16.5{\pm}8.7$ degrees in non-low back pain and averaged lordosis angle of resting sitting posture was $10.8{\pm}13.7$ degrees in low back pain, $18.9{\pm}9.6$ degrees in non-low back pain group but the difference in mean lordosis angles of two groups was not statistically significant. The results of this study indicate that professional drivers developed chronicity of low back pain due to unfit seat, poor habitual posture and stress from vibration or other risk factors. Therefore, there is need to improve work environment, i.e. enough resting, to set a seat to support lumbar spine properly and to provide comprehensive rehabilitation program including early diagnosis, proper treatment and education for self help management.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.72-84
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• 2000

To analyze the correlation between drivetrain systems and to optimize the vehicle design with satisfying of the initial design objects, the performance sensitivity analysis through the iterative design procedure must be carried out. In this study, effects of the design parameters for the main components of the parallel type hybrid drivetrain system are analyzed by using the developed method of the vehicle performance simulation, and the basis of the optimal selection of the design parameters from the relation of design constraints and required performances is suggested. In driving control of the parallel hybrid vehicle, power split ratio is the most important factor, and the improved drivetrain system can be constructed through the only change of the algorithm for determination of the power spilt ratio, which is strongly applicable to the driving patterns and the environments. Therefore, Various techniques, such as the change of the weighting factors and the range extended algorithm, are suggested and evaluated in this paper.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1827-1829
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• 2000

To replace the dual scan system by single scan in large ac plasma display(PDP), the addressing time should be reduced by modifying cell structure and driving circuits. Moreover. the luminance of the PDP can be also increased with the decrease in the addressing time. In this paper, various shapes of bus and address electrode have been investigated to reduce the addressing time in ADS driving method. The experimental results show that the addressing time can be reduced more than 30% compared to the conventional type by modifying the electrodes without reducing the luminance of the PDP.

• Journal of Information Display
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• v.2 no.1
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• pp.10-13
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• 2001

The addressing time can be reduced by modifying cell structure and/or driving circuits in order to replace the dual scan system by single scan in large ac plasma display panel(PDP). Moreover, the luminance of the PDP can also be increased by decreasing the addressing time. In this paper, various shapes of bus and address electrodes have been investigated with the aim of reducing the addressing time in ADS driving method. The experimental results show that the addressing time can be reduced by more than 30% compared with the conventional type by modifying the electrodes without reducing the luminance of the PDP.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.828-831
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• 2003

The benefits of the pneumatic valve with piezoelectric element are faster response times, low energy consumption, and the ability to be used in hazardous environments and field bus systems. In this paper, PZT actuator, 2 and 3 stages pneumatic valve were designed and manufactured. Also. characteristics of the pneumatic valve with piezoelectric element were tested with a testing system. It is confirmed that the PZT actuator is useful one for controlling the direction of pilot valve.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.282-284
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• 1997

The harmonics are injurious on the operation of the motor, electric instruments etc. In this paper, it is certified the capability of the electric measuring devices at the input/output of inverter. And it is measured the harmonics of the voltage and current waveforms. Also, this paper presents the efficiency of the inverter's power conversion by measuring the fundamental and total power at the input, DC bus and output.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.21 no.1
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• pp.49-56
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• 2015

Background: Although many of those who drive for a living are exposed to repetitive and awkward posture and whole body vibration which cause them cumulative trauma disorder, therapeutic studies related to the problems from the transport unit are still somewhat inadequate. The purpose of this case report is to identify the effect of combined exercise program on patients suffering chronic neck pain caused by long hour of intra-city bus driving. Method: A total of 4 subjects are selected as patients, all of whom have more than 10 years of experience in intra-city bus transportation services. These people have suffered from neck pain for years. We ran the combined exercise program 3 times a week for 4 weeks and respectively evaluated the results after the 2nd and 4th week. We implemented conventional physiotherapy for 40 minutes, another 40 minutes of combined exercise program, and then educated the patients to enable themselves to do active stretching program as a home program. The combined exercise program contained 3 different stages. 1st stage: active stretching program, 2nd stage combined stabilization exercise and strengthening exercise, 3rd stage: proprioceptive exercise Result: After 4 weeks of intervention, there was enhance in the range of motion. $12^{\circ}$ increase in flexion, $10^{\circ}$ in extension, $6^{\circ}$ in lateral flexion respectively, and $10^{\circ}$ in rotation on average. VAS(visual analgue scale) decreased by 33% on average, NDI(neck diability index) by 28% and fatigability by 23%. Conclusion: There were improved results in the range of motion, NDI, VAS, and in fatigability after applying combined exercise program to intra-city bus drivers exposed to whole body vibration and cumulative trauma disorder.

• Journal of Drive and Control
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• v.19 no.3
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• pp.39-46
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• 2022

In South Korea, to evaluate the rollover safety of domestic vehicles, the maximum slope angle of the vehicle is specified, which is verified by the rollover safety test of driving vehicles. However, the domestic rollover safety test is not suitable for buses, because the small amount of static stability factor (SSF) will invalidate the rollover experimental equation due to the high center of mass position of buses. To solve the above problems, a dynamic model of the bus is prepared with assumptions of mass and suspension spring properties. Subsequently, the maximum slope angle of the model was computed by using the simulation of multi-body dynamics, and the result was compared with actual test results to validate the dynamics model. Also, the rollover Fishhook (roll stability) test was conducted in the simulation for driving model. During the simulation, roll angle and roll rate were calculated to check if a rollover occurred. Through the rollover simulation of buses, the domestically regulated formula for rollover safety and the procedure of rollover test for driving vehicles are evaluated. The conclusion is that the present regulation of rollover test should be reconsidered for buses to ensure to get the valid results for rollover safety.