• Journal of Powder Materials
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• v.17 no.2
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• pp.123-129
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• 2010

The fabrication of interconnect from titanium powders and $TiN_x$ powders is investigated. Corrosion-resistant titanium and $TiN_x$ are used as reinforcement in order to reveal high heat and corrosion resistance at the elevated temperature. We fabricated the plates for interconnect reinforced with $TiN_x$ by mixing titanium powders with 10 wt.% of nano-sized $TiN_x$. Spark Plasma Sintering (SPS) was chosen for the sintering of these composites. The plate made of titanium powders and $TiN_x$ powders demonstrates higher corrosion resistance than that of the plate of titanium powders alone. The physical properties of specimens were analyzed by performing hardness test and biaxial strength test. The electrochemical properties, such as corrosion resistance and hydrogen permeability at high temperature, were also investigated. The microstructures of the specimens were investigated by FESEM and profiles of chemical compositions were analyzed by EDX.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.2
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• pp.135-151
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• 2014

It is very important to properly understand such "Transport Pathways" elements as "Pipe" and "Cell" pathways in commercial GoldSim Transport Module (GTM) for developing higer quality models and programs for performance assessment of complex radioactive waste repositories. With an illustrative case under an earthquake scenario, by which an increasement in the groundwater flow rate occurs though the geological medium, ways of avoiding possible modeling errors in the nuclide transport modeling in the radioactive waste repository system for its safety assessment by utilizing such pathways are discussed and a proper usage of the pathways is proposed.

• Journal of the Korean institute of surface engineering
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• v.51 no.1
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• pp.40-46
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• 2018

The light-weight of the research and development materials is actively carried out by overseas automobile companies and technology development continues in Korea. For the sake of fuel efficiency, the development of lightweight technology by improving the manufacturing method has been very effective. Recently, to maximize the effects of light weight, automotive interior parts have been applied by the micro-cellular injection molding using supercritical fluids and we call the Mucell manufacturing. This technique causes a problem in the quality of the surface of the products, because the shooting cells are revealed as the surface layer of the products by forming micro cells at the center of the products during injection molding. To overcome these phenomenon, we increased the temperature of injection molding using joule heating until critical value. In this study, we have predicted the problem of Mucell injection molding through the finite element analysis as changed the temperature by joule heating. From the result of finite element analysis, we have determined the optimized process and made the injection mold included electric current heating system with Mucell manufacturing analyzed the surface characteristics of the injection product according to changing mold temperature.

• Journal of the Korean Electrochemical Society
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• v.17 no.3
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• pp.201-208
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• 2014

A Pt catalyst ($Pt/G_xC_y$) supported on the hybrid supporting materials composed of graphene oxide (GO) and carbon black (C) was fabricated using polyol method to improve the durability of electrocatalysts. The electrochemical performances measured by cyclic voltammograms using three-electrode system revealed that the properly designed $Pt/G_xC_y$ catalyst exhibited higher durability than that of Pt/C catalyst without sacrificing an electrocatalytic acivity. In the oxygen reduction reaction (ORR) performed in acid solution with the rotating disk electrode, the $Pt/G_xC_y$ catalyst showed greater mass and area-specific activity than those of Pt/C catalyst.

• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.854-859
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• 2005

Performance of micro scale intermediate temperature solid oxide fuel cell system has been successfully evaluated by computer simulation based on macro modeling. Two systems were studied in this work. The one is designed that the ceria-based electrolyte placed between composite electrodes and the other is designed that electrodes alternately placed on the electrolyte. The injected gas was composed of hydrogen and air. The polarization curve was obtained through a series of calculations for ohmic loss, activation loss and concentration loss. The calculation of each loss was based on the solving of mathematical model of multi physical-phenomena such as ion conduction, fluid dynamics and diffusion and convection by Finite Element Method (FEM). The performance characteristics of SOFC were quantitatively investigated for various structural parameters such as distance between electrodes and thickness of electrolyte.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.577-586
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• 2011

This paper describes the development of hardware simulator for the operation analysis of DC microgrid. The hardware simulator consists of several distributed power sources such as a wind power generation, solar power and fuel cell, and two energy storages such as a supercapacitor and battery. The main controller which performs a role of energy management and state monitoring is connected with the local controller in each power source and storage through ethernet-based communication link. The developed hardware simulator can be utilized to analyze the performance DC microgrid with practical manner.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.4
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• pp.124-129
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• 2008

Design practice has been made on an oil-less scroll air compressor as an air supply device for a 2 kW fuel cell system where air pressure of 2 bar and flow rate of 120 liter/min are required. Basic structure of the scroll compressor includes double-sided scroll wrap for the orbiting scroll driven by two crankshafts connected to each other by a timing belt. These features can eliminate thrust surface which otherwise would produce frictional heat and jeopardize reliable operation of the orbiting scroll and the scroll element's deformation as well. This study focuses on optimum scroll wrap design; orbiting radius has been chosen as an independent design parameter. As the orbiting radius changes, scroll sizes such as scroll base plate and discharge port diameters change accordingly. Gas compression-related losses and mechanical loss also change with the orbiting radius. With a scroll base plate diameter of 120mm at most and discharge port of at least 10mm, the orbiting radius should be within the range of 2.5-4.0mm. With this range of the orbiting radius, it was estimated by performance analysis that the compressor efficiency reached to a maximum of ${\eta}_c$=96% at the orbiting radius of $r_s$=3.5mm for the scroll wrap height-to-thickness ratio of h/t=5.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.2
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• pp.87-92
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• 2011

This paper introduces the policy and regulations on very low level waste (VLLW) management in China. Given the important decommissioning and site restoration program of the old facility, it is considered necessary to create a new disposal facility dedicated to VLLW. Many general design principles are in common with to the disposal facility for low and intermediate level waste (LILW), namely the isolation of the waste by means of a multibarrier system, but using bentonite and/or high density polyethylene membranes instead of the generalized use of concrete barriers. The design of the facility is consistent with the design of disposal facilities for hazardous waste. The engineering design of two VLLW disposal facilities is introduced.

• Journal of the Korean institute of surface engineering
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• v.45 no.2
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• pp.75-80
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• 2012

A sputter-sublimation source was tested for high rate deposition of protective coating of PEMFC(polymer electrolyte membrane fuel cell) with high electrical conductivity and anti-corrosion capability by DC biasing of a metal rod immersed in inductively coupled plasma. A SUS(stainless steel) tube, rod were tested for low thermal conductivity materials and copper for high thermal conductivity ones. At 10 mTorr of Ar ICP(inductively coupled plasma) with 2.4 MHz, 300 W, the surface temperature of a SUS rod reached to $1,289^{\circ}C$ with a dc bias of 150 W (-706 V, 0.21 A) in 2 mins. For 10 min of sputter-sublimation, 0.1 gr of SUS rod was sputter-sublimated which is a good evidence of a high rate deposition source. ICP is used for sputter-sublimation of a target material, for substrate pre-treatment, film quality improvement by high energy particle bombardment and reactive deposition.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.289-290
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• 2012

This paper proposes a new active snubber boost PFC converter to provide a zero-voltage-switching (ZVS) turn-on condition and reduce electromagnetic interference (EMI) noise in home appliances and renewable energy applications, including solar or fuel cell electric systems. The proposed active snubber circuit enables a main boost switch of the boost-type PFC or grid converter to turn on under a ZVS condition and reduce the switching losses of the main boost switch. Moreover, for the purpose of a specialized intelligent power module (IPM) fabrication, the proposed boost circuit is designed to satisfy some design aspects such as space saving, low cost, and easy fabrication. Simulation and experimental results of a 2kW IPM boost-type PFC converter are provided to verify the effectiveness of the proposed active snubber boost circuit.