• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.115-121
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• 2008

In this paper, a three-dimensional computational fluid dynamic model of a proton exchange membrane fuel cell(PEMFC) with serpentine flow channel is presented. A steady state, single phase and isothermal numerical model has been established to investigate the influence of the GDL (Gas Diffusion Layer) parameters. The GDL is made of a porous material such as carbon cloth, carbon paper or metal wire mesh. For the simplicity, the GDL is modeled as a block of material having numerous pathways through which gaseous reactants and liquid water can pass. The porosity, permeability and thickness of the GDL, which are employed in the model parameters significantly affect the PEMFC performance at the high current region.

• Progress in Superconductivity and Cryogenics
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• v.8 no.4
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• pp.34-38
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• 2006

Cycle analysis was performed in order to find the optimum design point of the LNG Boil-off gas re-liquefaction system. Thermodynamic analysis revealed the system could be defined by three state variables. Thus the system performance could be described by the three cold endpoint temperatures of the three-pass heat exchanger. This enabled us to investigate the cycle performance in terms of the heat exchanger parameters. To get access to the cycle states of higher system performances, larger heat exchangers were found necessary. Also the thermal pinch in cryogenic heat exchangers was found to act as a limiting factor to the system performance.

• Particle and aerosol research
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• v.14 no.1
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• pp.9-16
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• 2018

We have developed an electrostatic precipitation (ESP) type air cleaner for indoor air quality and investigated its performances regarding CADR (Clean air delivery rate), single-pass efficiency and gas removal efficiency. The ESP air cleaner used an ACF (Activated carbon fiber) filter for gas removal and the ACF as a high voltage electrode for particle removal. The ESP air cleaner was tested in a chamber with the volume of $1m^3$ regarding CADR and gas removal efficiency. The applied CADR area of the ESP was $1.8m^2$. Gas removal efficiency was tested with 3 gases (Acetaldehyde, Acetic acid, Ammonia). As the results of the gas removal efficiency, the ESP air cleaner shows the removal efficiencies of 90, 98 and 85% for acetaldehyde, acetic acid and ammonia, respectively.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.393-397
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• 2001

The innovatory process, that is the direct separation and recovery of the iron and zinc metals contained in the high temperature exhaust gas generated from the electric arc furnace fer the inn scrap melting and/or the dust treatment, has been proposed. This proposed process consists of the moving coke bed filter that is directly connected to the electric furnace, and the following heavy metal condenser. The exhaust gas passes through the filter and the condenser right after exhausting from the electric furnace. The moving coke bed filter is being controlled at about 1000℃ and collects iron and slag components contained in the high temperature exhaust gas. Heavy metals such as zinc and lead pass through the filter as vapor. Based on the thermodynamic considerations, the iron oxide and the zinc oxide are reduced in the filter. The solution loss reaction rate is comparatively low at about 1000℃ in the coke bed filter by the analysis using the mathematical simulation model. The heavy metal condenser is installed in the position after the coke bed filter, and rapidly cools the gas from about 1000℃ to 450℃ by a full of the cooling medium like the solid ceramic ball in addition to the cooling from the wall. The zinc and lead vapor condense and separate f개m the gas in a liquid state. The investigation of the characteristics of the exhaust gas of the commercial electric arc furnace, the fundamental experiments of the laboratory scale and the bench scale ensured the formation of this proposed process. A small-scale pilot plant examination is carrying out at present to confirm the formation of the process. It is certain that the dust generation of the electric arc furnace is extremely decreased, and it can save the energy consumption of usual dust treatment processes by the realization of this process.

• Journal of Internet of Things and Convergence
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• v.8 no.1
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• pp.23-29
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• 2022

The product to be developed in this study is a heat recovery device which generates steam or hot water at high temperature and high pressure by heating water using exhaust gas from diesel engine, gas engine, gas turbine, etc. as an exhaust gas boiler off heat boiler(EGB) type for ship and power generation. The steam vapor or the created warm water is used as the power source required for the steerage heating and hot water facility or the HFO heating of the ship, and the turbine drive. The principle of waste heat boilers serves to heat water as high temperature exhaust gas with heat pass through the tube of the boiler. The heated water is a structure that is sent to a cabin or turbine device in the form of steam. In this study, the objective of this study is to maximize the efficiency by increasing the heat transfer surface by replacing the tube which is the heat transfer part of EGB with the plate tube.

• Polymer(Korea)
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• v.30 no.5
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• pp.391-396
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• 2006

It has been reported that plasma treatments are used to modify surface properties of polymers such as adhesivity hydrophobicity and hydrophilicity. Using plasma treatment, interfacial pro-perty can be introduced to a polymer surface without affecting the desired bulk properties of a material. In this study, commercial polyamide66 (PA66) /polyphenylene (PPE) polymer was modified by plasma treatment under a various gas specious for elimination of organic compound and polymer surface property with hvdrophilicity. PA66/PPE polymer with hydrophilicity was treated by RF plasma vacuum system under a various parameter such as gas specious, processing time and partial pressure. Hydrophilicity of PA66/PPE was confirmed by calculation of the surface free energy from contact angle measurement. The highest surface free energy of $50.03 mJ/m^2$ with the lowest contact angle of $14^{\circ}$ was obtained at plasma process power of 100 W, treatment time of 2 min and $Ar/O_2$ gases of 100 and 200 sccm. Moreover the change of organic compounds on the polymer surface was analyzed by fourier transforms infrared spectrometry (FTIR).

• Journal of the Korean Solar Energy Society
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• v.31 no.4
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• pp.9-18
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• 2011

This study assessed the performance of a compact heat exchanger with staggered tube banks for recuperation of high temperature exhaust thermal energy for SOFC fuel cell system. The compact heat exchanger in this study is two pass system which consists of $315{\times}202.5{\times}48.5mm^3$ and 132 tubes of $6.0mm{\Phi}$ for each heat exchanger. From experiments of the 2 pass heat exchanger system, air temperature was increased from $60{\sim}85^{\circ}C$ to $402{\sim}482^{\circ}C$ while gas temperature was decreased from $600^{\circ}C$ to $305{\sim}402^{\circ}C$ according to mass flow rates of 3.9~7.8 g/s. The experimental heat transfer rates of the heat exchanger were compared with CFD numerical solutions with the conventional ${\xi}-NTU$ method. From the comparisons, the following conclusions were obtained. For the heat exchanger system, the relative errors of heat transfer rate by CFD solution were from 7.1 to 27%, and those by ${\xi}-NTU$ method were from 0.6% to 21% compared with experimental data. From the comparisons, it can be said that both of CFD and ${\xi}-NTU$ method almost simulated to experimental data except specific conditions. Pressure drops through air tubes and gas passages were calculated with both of the CFD computation and head loss equations. The differences between them were from 14 to 22%.

• Particle and aerosol research
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• v.5 no.4
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• pp.159-170
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• 2009

A depth filter medium was newly designed in order to achieve high collection of dust and low pressure drop in this work. Multilayer depth filter media consist of an upstream layer of highly porous structure which allows particles to pass through and to follow by one or more downstream layers to hold the particles inside the media. For each filter media, flat sheet and pleated module were made of newly developed depth filter media and filter media of commercial products. Commercial depth filter cartridge for gas turbine air intake cleaning were used as reference for filtration area and pleat geometry of pleated modules. This work attempts to evaluate and compare the newly developed depth filter medium and two commercial filter media in terms of filtration parameters such as air permeability, initial pressure drop, particle retention and pressure drop variation with dust loading. According to the close examination the newly developed depth filter showed better performance compared to the commercial depth filter media.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2760-2769
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• 1996

The feedback control systems of welding process using visual information can improve weld qualities. However, it is very difficult to get the visual information of weld pool since the light intensity of welding arc is much stronger than that of the weld pool. To explore the possibility of extending the capability of automatic welding machines, a study of a closed loop controlled welding system consisted of a GTA welding machine, a vision system, a stepping motor system and a digital computer was undertaken. Particularly, in this system, a CCD camera with a long wavelength pass filter was used to get a better weld pool image. Subsequently, an image analysis technique has been developed to measure the weld pool width. Using this weld pool width measurement, a colsed loop control system adjusted welding speed to maintain a constant weld pool width.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1047-1052
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• 2008

The aim of this paper is that studies on the characteristics of the liquid-gas ejector. Could get data about various model using numerical analysis. Compare and analyze result that get by an experiment and numerical analysis. And studied Characteristics of the ejector. In this paper, Numerical analysis model is gotten divided according to each Throat ratio as three types. Each throat ratio is 0, 4 and 7.5. According to the result that analyze basic model, pressure became lower causing the volume flow rate increase. In CFD studies, Fixed volume flow rate by these result and analyzed ejector performance. As a result, there was no change of pressure to Throat's Enterance, and pressure became low while pass the throat. Since, pressure recovered while passing diffuser. The outer flow velocity did not change greatly to change of volume flow rate. This research expects that is utilized to data for performance elevation hereafter.