• KIPS Transactions on Computer and Communication Systems
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• v.3 no.3
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• pp.63-72
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• 2014

The exchangeable battery electric bus is an eco-friendly public transportation vehicle. Due to the technological limitation, however, it should repeatedly change batteries with charged ones. The unmanned battery exchangeable electric bus being studied in Korea can exchange batteries automatically by using a battery swapping system. In this paper, we propose an unmanned battery exchangeable electric bus management system. The proposed system provides two services: the bus information service and the battery change scheduling service. The bus information service is the existing traditional metropolitan area bus information systems, which inform bus passengers how long they should wait for the buses. Our second service assigns a low-battery bus, which needs to change the batteries, to the battery swapping system, which stores fully-charged batteries. To validate the proposed system, we model the system by using the DEVS formalism. The simulation result shows that the proposed system provides the services properly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.216-220
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• 2013

The rated voltage has been rising in order to minimize the losses in power transmission. The high voltage electric machines should be minimized due to the constraints of space. Therefore, the temperature of high voltage electric apparatuses easily exceeds the temperature limits. In this paper, it is investigated that how to minimize the internal temperature rising of a high voltage switchgear by adjusting the arrangement of bus bars. High voltage switchgears consist of a circuit breaker, a CT, a PT, a earthing switches, bus bars, and so on. It is very difficult to estimate the electromagnetic properties of a high voltage switchgear due to these various environments and structures. In this paper, analyses are focused on the electromagnetic characteristics of bus bars according to the arrangement method and the enclosures to simplify the electromagnetic characteristics of a switchgear. It is found that the characteristics of electric field intensity and electromagnetic losses in bus bars are influenced by the arrangement method of bus bars. However, it is confirmed that the electromagnetic characteristics of enclosures are not affected by the arrangement of bus bars. In this paper, the arrangement methods of bus bars to minimize the electric field intensity and electromagnetic losses are suggested. It is expected that the research results are helpful to design and develop an electrically reliable high voltage switchgear.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.220-224
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• 2012

The analysis on the bus bar effect is conducted to develop a cost effective 24kV/2,000A switchgear. The temperature enclosures and bus bars could rise due to several heat sources such as eddy current losses and copper losses. Therefore, a study on the characteristics of the electric field intensity and electromagnetic loss according to the bus bar size in a bus bar compartment is essential to design a electrically reliable high voltage switchgear. It is investigated that the electromagnetic influence to the temperature rising and the dielectric stability according to various bus bar sizes by using finite element method(FEM). The electric field intensity and electromagnetic loss according to various bus bar sizes are calculated to design a reliable and a high voltage switchgear. As results, it is found that the electromagnetic loss and the dielectric stability of bus bar could be determined by a bus bar size. It means that a cost effective 24kV/2,000A high voltage switchgear could be developed by selecting the proper size of a bus bar. Also, it is recognized that the electromagnetic characteristics according to various bus bar sizes in order to design an electrically stable high voltage switchgear when the enclosure size is determined as a fixed value. Futhermore, studies on the various nominal voltage class and bus bar sizes will be conducted to develop a cost effective high voltage switchgear.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.343-351
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• 2018

Renewable energy sources has drawn considerable attention as clean energy sources because of changing public attitudes regarding greenhouse gas and fine dust. Recently, in this respect, the government provides the drivers of electric vehicles with various benefits such as tax reduction, financial incentives and free parking from the public to the private sector. Plug-in electric vehicles are the most common in the private sector. Otherwise, different types of battery-based buses in the public sector are being developed, and there are three main types of charging: plug-in, battery swapping and wireless. Therefore, economic assessment of charging types in each bus route is required in order to facilitate the use of battery-based buses instead of the existing CNG buses. In this paper, net present value(NPV) and B/C ratio of charging types are evaluated in consideration of the bus schedule, the cost of charging station, and the life cycle of battery, etc. per each bus route. In case study, main bus routes in Daegu City are simulated with the proposed evaluation method to validate the eco-bus project.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.8
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• pp.334-340
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• 2006

Copper is widely used in electric wire, cable, conductor in electric devices. As the demand for electric power is increasing rapidly, electric power devices are getting amazingly bigger and complicated. The using of light-weight conductor can reduce the size and making cost of the electric devices. In high-frequency application, Electric current in a conductor tends to shift to the surface of the conductor, resulting in an uneven current distribution in the inner conductor. In the extreme case the current may essentially concentrate in the 'skin' of the inner conductor as a surface current. In high frequency application, therefore, inner area of copper conductor may replace with aluminum conductor, which reduces the weight of conductor. This paper describes the manufacture and evaluation of composite conductors made of copper and aluminum. The optimum extruding ratio was 16 at $300^{\circ}C$. The electrical resistance of manufactured composite bus bar was $57{\mu}{\Omega}$ at DC and $49.5{\mu}\{Omega}$ at 300Hz.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.1
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• pp.94-101
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• 2010

Optimization of interconnects among processors and memories becomes important as multiple processors and memories can be integrated on a Multi-Processor System-on-Chip (MPSoC). Since the optimal interconnection architecture is usually dependent on the applications, systematic design methodology for various data transfer requirements is necessary. In this paper, we focus on bus interconnection for MPSoC applications which use 4 ~ 16 processors. We propose a new systematic bus design methodology under performance constraints using Single Arbitration Multiple Bus Accesses (SAMBA) style bus architectures. Optimized bus architecture is found to satisfy performance constraints for a single or multiple applications. When compared to the unoptimized architecture, our method can reduce the bus switch logic circuits significantly (by more than 50% sometimes). Furthermore, low cost bus architectures can be found to satisfy the performance constraints for multiple applications.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.201-205
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• 2001

This paper presents the load modeling process and bus load models for KEPCO power system. At first, load devices commonly used in KEPCO power systems were selected, and tested for measuring the voltage and frequency sensitivity of active and reactive power. From this test, about 40 voltage and frequency dependent load models have been obtained. The bus load composition rate for KEPCO power system has been determined using the various recent surveys and papers in order to develop the load model for a power system bus. To verify the accuracy of developed bus load models, the field test for measuring active and reactive power according to artificial variation of the bus voltage was performed at 8 substations for spring summer, autumn, winter cases. With data of this seasonal field test, more reliable bus load models for KEPCO power systems were developed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.330-335
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• 2012

A Bus Trunk System for Wind Tower is introduced. A marine cable has been widely used in wind tower or other offshore structure. However, as the electric load capacity is getting increased, the large number of cable lines should be used to cover such a huge amount of electric capacities, which makes the installation make quite difficult due to the heavy weight and volume of the present cables. On the other hand, by using a single bus trunk system line, the power capacity amount of 16 number of cable can be delivered with significant compactness. However, unlike flexible cable, the bus trunk is relatively stiff which could arise resonance phenomenon in the operating condition of wind tower, therefore, the vibration characteristics of bus trunk should be investigated and verify its long-term reliability during the life time of the wind tower.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.593-598
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• 2008

The power distribution is proposed to determine the target operating points of the system components as the basis for maximal the efficiency of the overall system for a power split dual electric machine hybrid electric bus. The coordinated control is constructed on the basis of the power distribution. The basic coordinated control is implemented to satisfy the driver's power demand, in which both the dynamic characteristics of the engine and the dual electric machine are explicitly taken into account. Moreover, the improved coordinated control is suggested to suppress engine dynamic operation and rich fuel injection.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.62-64
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• 2001

This paper presents a new loss allocation scheme using power contribution method Power contribution is to find how much power at each generating/1oad bus is contributed to individual load/generating bus. In this paper power contribution is calculated using fundamental circuit theory. In numerical simulation, an illustrative example applying the proposed scheme to 6-bus test system is shown.