• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.309-317
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• 2022

There are 2,517 buses on 143 routes in Busan. One company is operating 36 hydrogen city buses (1.4%) and two hydrogen charging stations. By 2030, the number of hydrogen city buses will be increased to 500 and 40 hydrogen charging stations. In the survey of city bus companies, 61.5% of respondents answered 'not reviewing (at all)' and 23.0% of respondents '(actively) reviewing hydrogen buses'. And as for the level of help that hydrogen city buses give to bus companies, 23.5% answered 'helpful'. In order to promote the introduction of hydrogen city buses, first, it is necessary to stipulate support for hydrogen bus purchase cost and hydrogen charging station construction cost in related ordinances so that bus companies do not increase their burden of purchasing hydrogen buses in the future. Second, identify the number of new city buses introduced, convert about 50% to hydrogen city buses by the mid-term, and build 50% of the chargers in public garages with hydrogen chargers. Third, expand hydrogen refueling stations in city bus garages.

• Journal of the Korean Professional Engineers Association
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• v.33 no.4
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• pp.63-67
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• 2000

Presently, Weekend Buses only lane system is in force in Gyung-Bu Highway causes traffic delay at the northern of Su-won IC and have reduced the efficiency of Highway. To solve this problems, Buses only lane system is working at the northern of Su-won IC should be charged over from Median Buses only lane system to Curb Buses only lane system. It makes good effects on reducing weaving occurs when cars change lane, traffic accidents, ease control on violation cars, improving Level of Service in the Ramp, etc.

• Journal of Environmental Science International
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• v.21 no.2
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• pp.241-251
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• 2012

The emissions of several air pollutants ($NO_x$, CO, VOCs, etc.) for the replacement of all diesel buses by Compressed Natural Gas (CNG) buses were estimated in the Busan Metropolitan Area (BMA). These emissions were calculated from emission factors considering the different driving speeds with bus routes, distance traveled, and deterioration factors. For the purpose of this study, three categories of fuel type were selected: (1) the combination of diesel (65%) and CNG buses (35%) (DSL+CNG case), (2) all diesel buses (DSL case), and (3) all CNG buses (CNG case). The emissions of $NO_x$ and CO in the CNG case were estimated to be significant decreases (by about 50% and 98%, respectively) relative to the DSL case. Conversely, the emission of VOCs (980.7 ton/year) in the CNG case were a factor of 3.3 higher than that (299.8 ton/year) in the DSL case. In addition, the diurnal variations of emissions between two city buses (e.g. diesel and CNG) and all other vehicles were distinctly different because the two city buses operate at a regular time interval. Our overall results suggest the possibility that the pollutant emissions from the CNG buses can exert less influence on air quality in the target area than those from the diesel buses.

• Journal of Korean Society of Transportation
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• v.13 no.4
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• pp.105-115
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• 1995

This paper deals with an operation concept of "time-transfer of buses", in which buses arrive a transfer center at the same time and allow passengers to transfer to other bus lines, so that passengerscan go anywhere all the timed-transfere buses operate with only one transfer. This timed-transfer bus system is known as an efficient operating technique which can be adopted in an area with sparsely distrubuted bus demand. A model of timed-transfer is estabilished in terms of vaious factors such as the expected(or average) arrival time, distribution of arrival time, timed-transfer cycle, shceduled departure time, etc. It is assumed that the objective of timed-transfer bus system is to minimize the total transfer waiting time. The optimal schedualed arrival time or buffer time(time required to arrive ealy in consideration of delay) is analyzed for a general case and various speicial cases. It was found that the optiaml buffer time is an inverse funcion of the timed-transfer cycl and increases with the cycle time, assumin g that there is a fixed scheduled departure time at the transfer cetner regardless of whether one or more buses fail to arrive before the scheduled departure time. If buses are to wait uhtil all the buses arrive at the transfer center, that is, the transfer departure time is vairable, the optimal scheduled arrival times can be obtained by a mathmatical programming.

• Fire Science and Engineering
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• v.18 no.2
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• pp.57-67
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• 2004

The results of the risk assessing on general buses, consisting mainly of diesel-fueled buses, show that the frequency of the instantaneous release is 1.4${\times}$10$^{-3}$ /bus/year, from which the probability of the formation of fireball as a sub event becomes 1.7${\times}$104, and show that the leakage from the CNG-fueled buses is 0.002 event/year. Also, the frequency of gradual release due to a crack is estimated at 3.7${\times}$10$^{-3}$ /buses/year, and a subsequent probability at which this could lead to a jet flame as a sub event is 1.2${\times}$10$^{-3}$ This corresponds to 0.04event/year for the CNG-fueled buses. Dividing all the fired casualties by the running distance of diesel-fueled buses, the risk is 0.091 fire fatalities per 100-million miles. And the total fire risk fur CNG buses is approximately 0.17 per 100-million miles of travel. This means that CNG buses is twice or more dangerous than diesel buses. After all CNG buses are more susceptible to the major fires. In the aspect of the reliability of this study, generic models and the failure data used in assessing the risks of CNG buses are appropriate. However, more accurate physics-based models and databases should be supplemented with this study to provide the better results.

• Journal of IKEEE
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• v.24 no.3
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• pp.821-827
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• 2020

In particular, vehicles with internal combustion engines of public transportation such as diesel and CNG buses are in urgent need of measures to reduce emissions as they have a long daily total mileage, long driving hours and a large number of vehicles. In this paper, the fuel consumption rate (km/kWh) was actually measured through road test of electric buses. Based on the measured values, CO₂ emissions from internal combustion engines and electric buses were calculated per bus. In addition to environmental improvement effects such as the expected reduction of carbon dioxide compared to CNG buses when replacing city buses with electric buses, additional effects were analyzed when the replacement of CNG buses is expanded to electric buses.

• Journal of Korean Society for Quality Management
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• v.46 no.4
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• pp.899-910
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• 2018

Purpose: Generally, since the population density is lower in suburban areas, the distance to school is inevitably long. Therefore, schools in suburban areas often operate school buses to improve student welfare. However, since school buses are usually used only during going to and from school, the utilization rates are relatively low. Therefore, this study aims to establish integrated operation plan of public school bus covering all schools. Methods: It is necessary to decide which school buses will serve the specific demand node which want to go to certain school in order to design an integrated operation plan for school buses. Therefore, a mathematical model is developed for minimizing the total number of vehicles and the distance of transportation by reflecting the characteristics of school buses and students as constraints. To solve the proposed mathematical model, CPLEX, a commercial solver, is applied. Results: To validate and to confirm the proposed process, numerical example is designed with the comparison between before and after integrated operations of school buses in terms of total operation cost. The result shows that the integrated operation can lead the reduction of the number of school buses as well as the decreasing of the fuel cost. Conclusion: This study provides the quantitative method to perform the integrated operation of school buses in suburban areas. The optimal operation strategy is required because there are more complex decision-making elements considering the integrated operation. It is expected to apply this research result at real situation to expand this services based on an optimal operation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.214-220
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• 2012

About 12 million people of the mobility handicapped were increased by the end of 2009 year. Universal design concept has been implemented in developed countries. Since 2004 low-floor buses are in Korea. In this study, there is no provision for mobility handicapped and small buses that can be comfortable riding car ramp design presented. The gate of a small buses lowered height of 200mm. Install the ramp in the center of the ramp by an air cylinder moves from side to side. The slope of the ramp was controlled by a hinge. Air cylinder thin type applicable in the narrow space of the slide cylinder was used.

• Journal of Information Processing Systems
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• v.7 no.1
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• pp.85-92
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• 2011

This paper shows an effective partitioning of static global row/column buses for tightly coupled 2D mesh-connected small processor arrays ("mesh", for short). With additional O(n/m (n/m + log m)) time slowdown, it enables the mesh of size $m{\times}m$ with static row/column buses to simulate the mesh of the larger size $n{\times}n$ with reconfigurable row/column buses ($m{\leq}n$). This means that if a problem can be solved in O(T) time by the mesh of size $n{\times}n$ with reconfigurable buses, then the same problem can be solved in O(Tn/m (n/m + log m)) time on the mesh of a smaller size $m{\times}m$ without a reconfigurable function. This time-cost is optimal when the relation $n{\geq}m$ log m holds (e.g., m = $n^{1-\varepsilon}$ for $\varepsilon$ > 0).

• 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.