• Proceedings of the KSR Conference
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• 2005.05a
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• pp.320-325
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• 2005

Power of fuel cell tram is supplied by only fuel cell system or hybrid system of fuel cell and battery/super capacity. Fuel cell is operated by hydrogen, which is fed directly from hydrogen tank or by reforming gasoline or methanol into hydrogen. Power system is preferred with hybrid of fuel cell and battery/super capacity since it improves total energy efficiency through interaction of hybrid components and restores energy regenerated by braking. Also, power supply system by fuel cell hybrid should be designed to output optimum energy efficiency depending on driving mode of fuel cell tram.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.2
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• pp.1-6
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• 2013

In high-speed vehicle, selection of fuel, configuration of components and cooling system are required to solve the heating issue by aerodynamic heating and inner combustion process. This subsystem consists of fuel tank, supply pump, various control valve, heat exchanger, including reactor, connecting line, adiabatic structures and insulations. In this paper, applicable fuel property is considered at flight characteristic of hypersonic vehicles. In this regard, current state of fuel/cooling system technology is identified.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.386-392
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• 1991

If we rely only on the conventional technology, It may be difficult to meet the recent requirments to electric power system such as further improvement of the quality of electric power supply, technology problems environmental compatibility and so on. Nowadays, power engineers much interest in applying new technology to power system industry. It is confirmed the technology of superconductivity applied components plays an important role in solving the problems of power system, because superconductors, used in suitable applications, can make electric power equipment smaller, lighter, more efficient and perhaps with better dynamic response. Two specific applications are considered here : electric machinery (Generators, Superconducting Magnetic Energy Storage, Transformer, Current limitter) and transmission line. The paper addresses the limitation of conventional technology, the technology impact & problems of superconductivity applied components to future power system from qualitative and some quantitative viewponts. The paper close with questions posed to simulate thinking on how superonductivity might be applied to power systems on a holistic basis.

• Journal of Aerospace System Engineering
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• v.5 no.1
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• pp.13-16
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• 2011

All components such as structure, engine, electrical equipment, wire etc. should have certified qualities and functions for safe flight. The wire like a blood vessel of man is connected with most components and supply a electrical signal or power to them and only certified wire through a lot of tests such as rating, flame resistance, self-extinguishing, protection of EMI etc. must be used in aircraft. In other words, the wire should observe many certification requirements because it is one of the most important components.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.437-447
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• 2015

In this paper, implementation of an integrated transformer applicable to power supply units (PSUs) for a 150-W LED with a wide range of output voltage is presented. The transformer is comprised of a PFC inductor and an LLC resonant transformer, each of which is placed and integrated on an E-I-E-type magnetic core. Integrated transformers with two different air gap topologies (i.e., the side and center gap topologies) are considered in the design phase to investigate their applicability. The design consideration on the LLC resonant converter used for the wide-output-voltage control ranges is described, and the overall performance of the proposed system is verified through realization of it onto a 150-W LED PSU board.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.117-126
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• 2009

A Common-Rail Direct Injection(CRDI) system for high speed diesel engines was developed to meet reductions of noise and vibration, and emission regulations. In this study, CRDI system analysis model which includes fuel and mechanical sub-systems was developed using commercial software, AMESim in order to predict characteristics for various fuel injection components. Each component which constructs system was modeled and verified by sub-model of AMESim obtained characteristics curves of each components. The parameter sensitivity analysis such as throttle size, injection rate, plunger displacement, supply pressure of fuel injection for system design were carried out by the analysis.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.70-82
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• 2014

A nano-power CMOS voltage reference is proposed in this paper. Through a combination of switched-capacitor technology with the body effect in MOSFETs, the output voltage is defined as the difference between two gate-source voltages using only a single PMOS transistor operated in the subthreshold region, which has low sensitivity to the temperature and supply voltage. A low output, which breaks the threshold restriction, is produced without any subdivision of the components, and flexible trimming capability can be achieved with a composite transistor, such that the chip area is saved. The chip is implemented in $0.18{\mu}m$ standard CMOS technology. Measurements show that the output voltage is approximately 123.3 mV, the temperature coefficient is $17.6ppm/^{\circ}C$, and the line sensitivity is 0.15 %/V. When the supply voltage is 1 V, the supply current is less than 90 nA at room temperature. The area occupation is approximately $0.03mm^2$.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1227-1234
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• 2015

The efficient electric power demand management in electric power supply industry is currently being changed by distributed generation. Meanwhile, small-scale distributed generation systems using renewable energy are being constructed worldwide. Several small-scale renewable distributed generation systems, which can supply electricity to the grid at peak load of the grid as per policy such as demand response programs, could help in the stability of the electric power demand management. In this case, the power quality of the small-scale renewable distributed generation system is more significant. Low prices of power semiconductors and multilevel inverters with high power quality have been recently investigated. However, the conventional multilevel inverter topology is unsuitable for the small-scale renewable distributed generation system, because the number of devices of such topology increases with increasing output voltage level. In this paper, a single-phase multilevel inverter based on H-bridge, with DC_Link divided by bi-directional switches, is proposed. The proposed topology has almost half the number of devices of the conventional multilevel inverter topology when these inverters have the same output voltage level. Double Fourier series solution is mainly used when comparing PWM output harmonic components of various inverter topologies. Harmonic components of the proposed multilevel inverter, which have been analyzed by double Fourier series, are compared with those of the conventional multilevel inverter. An inverter prototype is then developed to verify the validity of the theoretical analysis.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.4
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• pp.31-37
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• 2013

In this paper, we develop an efficient approach to solve a continuous review inventory system with a budget constraint when the semi-finished product and optional components are required to be assembled. We are, in particular, interested in a budget constraint that includes a service level. The service cost, such as labor and facility costs, tends to increase as the service level increase, and it makes the problem difficult to solve. Assuming that the reorder point for a semi-finished product is given, we show that the order quantity for the semi-finished product and the order quantity and reorder point for optional components can be determined by minimizing the total cost that includes setup cost, inventory holding cost, and shortage cost. The performance of the proposed approach is tested by numerical examples. By using sensitivity analysis, we conclude that, as the reorder point for semi-finished product increases, the order quantity for semi-finished product increases, whereas the order quantity and reorder point of optional components decreases.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.13-14
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• 2011

The main purpose of this research is to propose standardization of construction components design with BIM and to develop WLCM Framework and Application System for supply chain management on interaction of stakeholders based on proposed standard component. To accomplish main purpose of this research, we planned three years period, in first year, we will develop model for building lifecycle based on BIM, and this model can give the chance of collaboration with stakeholders of building project. In second year, we will develop WLCM system with model, and to improve performance of application model/system. This study can contribute on reduction of whole lifecycle cost, with preventing omission of factors on cost reduction possibility, develop concurrent engineering framework for construction stakeholders with proposed BIM.