• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.102-107
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• 2014

Because of high oil prices and emission gas problems, many governments tighten regulation of fuel economy and emission gas. For Passenger car, there are many researches for plug-in hybrid electric vehicles and they are being manufactured. On the other hand, there are few researches for plug-in hybrid electric bus that is heavy commercial vehicle. In this study, analysis of fuel economy for series plug-in hybrid electric bus according to engine operation strategy based on simulation is conducted. Forward simulator is developed using Autonomie. Engine operation strategies consist on constant engine operation strategy and engine on/off operation strategy. Considering the engine operation strategy, results of vehicle speed, engine operating points and fuel economy are obtained and analyzed. As a result, engine on/off operation strategy has more advantage than constant engine operation strategy in terms of fuel economy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.3
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• pp.40-49
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• 2011

This paper presents novel circuit topology of half-bridge soft-switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed, half-bridge high frequency PWM inverter with a high frequency planar transformer link PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode-equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC bus lines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, high switching frequency IGBTs can actually be selected in the frequency range of 40[kHz] under the principle of soft-switching. The performance evaluations of the experimental setup are illustrated practically.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1741-1746
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• 2022

As the use of school buses becomes more common, related laws are being enacted, such as making it mandatory for children to check school bus dropouts due to frequent accidents caused by the negligence of school bus drivers and their guardians. In this paper, we propose a safe school bus system that links efficient radio-frequency identification (RFID) and mobile APP in terms of energy utilization and cost. The school bus system uses RFID cards to check information on children boarding the school bus, and real-time SMS transmission allows parents to safely send their children to and from school. Instructors on the school bus can check their children's disembarkation information once more through APP, preventing various accidents that may occur to children left on the bus. Due to the automation of the school bus operation log, daycare center teachers can not only check the information on getting on and off, but also manage the information on the attendance and discharge of the students.

• Fire Science and Engineering
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• v.32 no.2
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• pp.82-91
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• 2018

This study analyzed the working conditions and problems of screen fire shutters in the Goyang Bus Terminal fire based on the fire investigation results. At that time, screen fire shutters in the 1st basement, which was under construction, did not work because the power was shut off. Four screen fire shutters in the 1st and 3rd floor did not work despite the power not being shut off. The following problems related to a screen fire shutter were found: shutting off the power to screen fire shutters for the fire compartment on each floor, even when the fire compartments were changed in each area; installing an integral type screen fire shutter without any regulations, installing a two-stage screen fire shutter in a place not related to obstacles during evacuation; stopping the function of the screen fire shutters for a fire compartment on each floor after a combustible sandwich panel was comparted; installing a screen fire shutter over 10 meters in width, in which its performance was not verified; and no safety control standards for reinstalling or maintaining a screen fire shutter.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.71-79
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• 2004

Packet-type data transmission is characterized by the continuous transmission of massive data with relatively constant rate. In such transmission, the dynamic power consumed on buses is influenced by the sequence of transmitted data. A new coding scheme called Sequence-Switch Coding (SSC) is proposed in this paper. SSC reduces the number of bus transitions in the transmission of packet-type data by changing the sending order of the data. Some simple algorithms are presented, In. The simulation results show that SSC outperforms the well-known Bus-Invert Coding with these algorithms. SSC is not a specific algerian but a method to reduce the number of bus-transitions. There could be lots of algorithms for realizing SSC. The variety of SSC algorithms provides circuit designers a wide range of trade-off between performance and circuit complexity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.106-107
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• 2018

Since Many person go to work or get off, it is difficult to use the public transportation comfortably on the morning or the evening. In this paper, we implement the passenger notification system on the bus using the NFC. The implemented system counts the number of passengers with the NFC reader for the fare. The user is able to find out the crowds of the bus transferred from the server before hop-in.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.311-315
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• 1998

Load Flow calculation methods can usually be divided into Gauss-Seidel method, Newton-Raphson method and decoupled method. Load flow calculation is a basic on-line or off-line process for power system planning, operation, control and state analysis. These days Newton-Raphson method is mainly used since it shows remarkable convergence characteristics. It, however, needs considerable calculation time in construction and calculation of inverse Jacobian matrix. In addition to that, Newton-Raphson method tends to fail to converge when system loading is heavy and system has a large R/X ratio. In this paper, matrix equation is used to make algebraic expression and then to solve load flow equation and to modify above defects. And it preserve certain part of Jacobian matrix to shorten the time of calculation. Application of mentioned algorithm to 14 bus, 39 bus, 118 bus systems led to identical result and the number of iteration got by Newton-Raphson method. The effect of time reduction showed about 28%, 30%, at each case of 39 bus, 118 bus system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.1-9
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• 2012

This study proposed a method to determine the number and location of bus information terminals (BIT), which is a device to provide passengers with bus arrival time at bus stops in a Bus Information System (BIS). In low-density area, it is not efficient to survey bus demands such as the number of passengers at all bus stops due to time and cost. This kind of a survey would, however, competently cover all bus stops if performed inside the bus. The number of riding-on and -off passengers is observed for every bus stop, and this data collection is repeated over all day. Data obtained from the survey are aggregated each bus stop. This study defines Utility Index (UI), an aggregate each bus stop. Bus stops are ranked according to UI and determined for a BIT within budget limitation. As a case study, a bus line in Jeju island, Korea, was dealt with. This case showed that the more aggregate the better data quality. This study is expected to contribute to solving a location problem of BITs in a BIS.

• Journal of Korean Society of Transportation
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• v.33 no.2
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• pp.170-181
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• 2015

This study explores passengers' travel characteristics at six bus stops on the Seoul Ring Expressway using smart traffic card data. Based on the characteristics, political strategies to improve bus facilities on expressway are suggested. Firstly, among them two bus stops of Guri and Uiwang-Cheonggye have higher transfer rate of passengers, 37.56% and 36.9% of the total intercity (red) bus passengers on the expressway, respectively. Secondly, Uiwang-Cheonggye bus stop has the highest transfer rate, and Guri bus stop has also higher transfer rate and the highest on-and-off passengers. It implies that both bus stops need to be prioritized for improving bus stop facility, access roads, and connection facility between the bi-directional stops. Thirdly, Guri (down) bus stop has relatively longer waiting time for transfer, thus shorter bus headways running the bus stop should be considered. Lastly, most passengers using both stops come to and from Bundang-gu in Geongnam City. Overall, the results of this study would be helpful for transport planners to develop effective bus route policies and bus operation.

• Journal of Power Electronics
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• v.11 no.4
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• pp.424-429
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• 2011

In this paper, the simulator of an on-line monitoring system for the range extender electric vehicle has been developed. The messages from the four control modules, the air pressure and fuel level sensors data, and the on/off switching states of 31 indicator lamps can be received through the control area network (CAN), and displayed on the graphic panel. The simulator was designed using the four DSP boards, variable resistors, and toggle switches instead of the four control modules, sensors, and switching state of indicator lamps on an actual series hybrid electric vehicle (SHEV) bus, respectively. The performance of the monitoring technologies was verified with the simulator at the laboratory, and then it was tested on an actual SHEV bus. The simulator is very useful at the initial development of the monitoring system at the hybrid-type or electrical vehicles.