In-Su Cha

An analysis of PEMFC & photovoltaic 500W hybrid system

Renewable energy sources (solar, wind, etc) are attracting more attention as alternative energy sources to conventional fossil fuel energy sources. Hydrogen energy and photovoltaic is friendly to the environment. In this paper a 500 W PV-fuel cell hybrid generation system is designed. An electrolyzed coupled to the PV array is employed for hydrogen production. Maximum power tracking for PV array is achieved using fuzzy regression. A controller is designed to ensure continuous constant power generation through the day and after sunset via the PV and fuel cell stack. The system is simulated using LabVIEW software. The system characteristics obtained from simulation are analyzed.

A low-energy compact electron beam irradiator for core-loss reduction of silicon steel

A new compact, low-energy electron beam irradiator has been developed. The core loss of silicon steels can be reduced by the magnetic-domain refinement method. The irradiator was developed for the application of core-loss reduction using the method. The beam energy of the irradiator can be varied from 35 to 80 keV and the maximum current is 3 mA. The irradiation area is designed to be 30/spl times/30 mm/sup 2/ now and will be upgraded to 30/spl times/150 mm/sup 2/ using a scanning magnet and scanning cone. The electron beam generated from 3 mm diameter LaB/sub 6/ is extracted to the air for the irradiation of the silicon steels in the air. A special irradiation port was developed for this low-energy irradiator. A havar foil with 4.08 /spl mu/m thickness were used for the window and a cold air-cooling system keeps the foil structure by removing heat at the window. The irradiator system and its operation characteristics are discussed.

Multi-layered Coating Deposited on PEMFC (Proton Exchange Membrane Fuel Cell) Bipolar Plates

The surface region of commercial stainless steel 304 and 316 plates has been modified through deposition of the multi-layered coatings composed of titanium film (0.1 ㎛) and gold film (1-2 ㎛) by an electron beam evaporation method. XRD patterns of the stainless steel plates deposited with conductive metal films showed the peaks of the external gold film and the stainless steel substrate. Surface microstructural morphologies of the stainless steel bipolar plates modified with multi-layered coatings were observed by AFM and FE-SEM images. The stainless steel plates modified with 0.1 ㎛ titanium film and 1 ㎛ gold film showed microstructure of grains of under 100 ㎚ diameter. The external surface of the stainless steel plates deposited with 0.1 ㎛ titanium film and 2 ㎛ gold film represented somewhat grain growth of Au grains in FE-SEM image. The electrical resistance and water contact angle of the stainless steel bipolar plates modified with multi-layered coatings were examined with the thickness of the gold film.

A study of operating characteristics for 1kW households PEMFC system

This paper discusses an actual operation of a monitoring system for fuel cells which will probably be substituted for the next generation environmental energy sources. Through this demonstration from monitoring system of 1 kW fuel cell for a house, the electrical and heat efficiency of fuel cell is able to be improved, and several faults of fuel cell, such as high expense and weak durability, would also be remedied dramatically.

Design of Web Based Monitoring and Control System for Photovoltaic System

Abstract Digital environment that is represented to intern et is displacing business way of industry and business achievement way with the fast speed being giving great change on life whole, improve existence business process utilizing internet and Web connection technology, information superhighway to tradition industrialist manufacture and etransformations propulsion that wish to maximize productivity and administration efficiency is spread vigorously. In this paper, we wish to accomplish generation equipments heighten stability and believability through remote monitoring and control of PV system. This paper describes the design of the monitoring system for sensing the monitoring data and indirect controlling of the PV system. Most of the conventional monitoring system depend on the special hardware and software. Basic design goal of monitoring system is to provide the convenience for the user and the portability for the system. In order for the system to fulfill its requirements, it was designed using Labview GUI facility based on the Windows 2000 environment of IBM PC compatible and Addon card based on the TCP/IP protocol. Advantage of the monitoring system are a personnel expenses curtailment effect, free of the place restriction and unmanned system of the generation plants, etc .

A compact low-energy electron beam irradiator.

A new compact low-energy electron beam irradiator has been developed. The irradiator generates an electron beam to the air with energy variable from 35 to 80 keV and with a maximum current of 1 mA. The irradiation area is 30 x 30 mm2. A special irradiation port is developed for this low-energy irradiator. The electron beam is generated from a thermionic LaB6 cathode in vacuum. The beam is extracted to the air through a havar foil window. The thickness of the window is 4.8 microm, it is vacuum-tightly connected to the window to support by an indium wire. A controlled bow geometry of the window helps the thin window withstand the vacuum pressure. Cold air generated from a vortex tube cools down both the window and its support in order to prevent the window from melting down, due to beam energy dissipated in the foil. We found that about 60% of the beam current is extracted to the air at 80 keV.

A study on the systematization design method of differential transformer

We introduce the systematization design method using similarity theory which is profitable in the compatibility, the reduction of construction time and price. The design method can make us predict the characteristic experiment for the magnitude we desire as the expression equation applied continuously. We can induce the design sample the users demand with the verification of the data on optimum design. Therefore, in the case of designing and developing the products, the systematization design method is very useful for the standardization of the developed goods, compatibility, the reduction of construction time and price. In this paper, we present the analogical algorithms of systematization design using similarity theory design factors and processing method of the restriction factors. Also, we analyzed the output voltage in terms of input voltage and displacement as choosing a differential transformer as the model.