• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1889-1894
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• 2017

Global automobile manufacturers are developing electric vehicles (EVs) to eliminate the pollutant emissions from internal combustion vehicles and to minimize fossil fuel consumptions for the future generations. However, EVs have a disadvantage of shorter traveling distance than that of conventional vehicles. To answer this shortfall, more batteries are installed in the EV to satisfy the consumer expectation for the driving range. However, as the energy capacity of the battery mounted in the EV increases, the amount of heat generated by each cell also increases. Naturally, a better battery thermal management system (BTMS) is required to control the temperature of the cells efficiently because the appropriate thermal environment of the cells greatly affects the power output from the battery pack. Typically, the BTMS is divided into an active and a passive system depending on the energy usage of the thermal management system. Heat exchange materials usually include gas and liquid, semiconductor devices and phase change material (PCM). In this study, an application of PCM for a BTMS was investigated to maintain an optimal battery operating temperature range by utilizing characteristics of a PCM, which can accumulate large amounts of latent heat. The system was modeled using Dymola from Dassault Systems, a multi-physics simulation tool. In order to compare the relative performance, the BTMS with the PCM and without the PCM were modeled and the same battery charge/discharge scenarios were simulated. Number of analysis were conducted to compare the battery cooling performance between the model with the aluminum case and PCM and the model with the aluminum case only.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.487-488
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• 2006

Novel bisphenol-based wholly aromatic poly(ether sulfone-ketone) copolymer containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of 4,4-difluorobenzophenone, 2,2'-disodiumsulfonyl-4,4'-fluorophenylsulfone (40mole% of bisphenol A) and bisphenol A. Polymerization proceeded quantitatively to high molecular weight in N-methyl-2-pyrrolidinone at $180^{\circ}C$. Organic-inorganic composite membranes were obtained by mixing organic polymers with hydrophilic $SiO_2$ (ca. 20nm) obtained by sol-gel process. The polymer and a series of composite membranes were studied by FT-IR, $^1HNMR$, differential scanning calorimetry (DSC) and thermal stability. The proton conductivity as a function of temperature decreased as $SiO_2$ content increased, but methanol permeability decreased. The nano composite membranes were found to posse all requisite properties; Ion exchange capacity (1.2meq./g), glass transition temperatures $(164-183\;^{\circ}C)$, and low affinity towards methanol $(4.63-1.08{\times}10^{-7}\;cm^2/S)$.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.269-269
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• 2006

The molecular structure of poly(2,6-dimethyl-4,4' -phenylene oxide)-g-poly (styrenesulfonic acid) (PPO-g-PSSA) graft copolymer was designed, and synthesized via living radical polymerization. Obtained graft copolymers were transformed into proton exchange membranes for direct methanol fuel cell (DMFC) application. The performance of the membranes was measured in terms of water uptake, proton conductivity, methanol permeability, and thermal stability. Very low methanol permeability and good proton conductivity were observed by adjusting grafting frequency and PSSA block content.

• Journal of Electrochemical Science and Technology
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• v.7 no.3
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• pp.206-213
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• 2016

Transition metal oxide-based electrodes for lithium ion batteries have recently attracted much attention because of their high theoretical capacity. Here we report the electrochemical behavior of cobalt oxide nanorods as anodes, prepared by a template-free, one-step electrochemical deposition of cobalt nanorods, followed by an oxidation process. The as-deposited cobalt has a slightly convex columnar structure, and controlled thermal oxidation produces cobalt oxides of different Co/O ratios, while the original shape is largely preserved. As an anode in a rechargeable lithium battery, the Co/O ratio has a strong effect on initial capacity and cycling stability. In particular, the one-dimensional Co@Co_xO_y core shell structure obtained from a mild heat-treatment results in superior cycling stability.

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.773-784
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• 2023

In this study, a comparative analysis between an electric heat pump cooling system and a hybrid desiccant cooling system is conducted. Desiccant cooling is a thermal driven system with potentially lower electric power consumption than electric heat pump. Hybrid desiccant cooling system simulation includes components such as a desiccant rotor, direct and indirect evaporative coolers, heat exchangers, fans, and a heat pump system. Using dynamic simulations by climate conditions, house cooling temperatures and power consumption for both systems are analyzed for 16 days period in the summer season under climate scenarios for the year 2100 prediction. The results reveal that the hybrid desiccant cooling system exhibits a 5-18% reduction in electric consumption compared to the heat pump system.

• Polymer(Korea)
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• v.34 no.1
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• pp.45-51
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• 2010

This study focuses on the investigation of the possibility of the crosslinked poly (vinyl alcohol) membranes with both poly (acrylic acid-co-maleic acid) (PAM) and 3-(trihydroxysilyl)-1-propane-sulfonic acid (THS-PSA) for the direct methanol fuel cell application. In order to characterize the prepared membranes, the water content, the thermal gravimetric analysis, the ion exchange capacity, the ion conductivity and the methanol permeability measurements were carried out and then compared with the existing Nafion 115 membrane. The ion exchange capacity of the resulting membranes showed 1.6~1.8 meq./g membrane which was improved than Nafion 115, 0.91 meq./g membrane. In the case of the proton conductivity, the THS-PSA introduced membranes gave more excellent $0.042{\sim}0.056\;S{\cdot}cm^{-1}$ than Nafion 115, $0.024\;S{\cdot}cm^{-1}$. On the other hand, the methanol permeability was increased more than Nafion 115 for all the range of THA-PSA concentration.

• Carbon letters
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• v.15 no.1
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• pp.38-44
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• 2014

This paper reports the effect of adding reduced graphene oxide (RGO) as a conductive material to the composition of an electrode for capacitive deionization (CDI), a process to remove salt from water using ionic adsorption and desorption driven by external applied voltage. RGO can be synthesized in an inexpensive way by the reduction and exfoliation of GO, and removing the oxygen-containing groups and recovering a conjugated structure. GO powder can be obtained from the modification of Hummers method and reduced into RGO using a thermal method. The physical and electrochemical characteristics of RGO material were evaluated and its desalination performance was tested with a CDI unit cell with a potentiostat and conductivity meter, by varying the applied voltage and feed rate of the salt solution. The performance of RGO was compared to graphite as a conductive material in a CDI electrode. The result showed RGO can increase the capacitance, reduce the equivalent series resistance, and improve the electrosorption capacity of CDI electrode.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.77-77
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• 2015

Metallic glass alloys having dense packing structure have short range ordered structure with long range homogeneity. Therefore, they can provide complete corrosion protection and unique electrical properties. Recently, metallic glass thin films have received much attention to extend its application fields combining with PVC coating technologies. The metallic glass thin films can change the surface properties of the conventional bulk materials which need anticorrosion properties. However, multi-component alloying targets are required to fabricate the metallic glass thin films because metallic glass alloys contain more than three elements. Recently, many researchers have been reported the properties of the metallic glass thin films synthesized with multi-cathode systems or amorphous target. But, it is difficult to fabricate the large sized sputtering targets for mass production equipment with high toughness and thermal stability. In this study, newly developed sputtering target with glass forming ability and the properties of the metallic glass thin films will be introduced with respect to the various application fields such as bipolar plate in PEM fuel cell and decorative coatings for electric device and construction fields.

• Polymer(Korea)
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• v.35 no.4
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• pp.296-301
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• 2011

This study focuses on the investigation of the impregnation of poly (vinyl alcohol) (PVA) crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) to porous polyethylene membrane for the fuel cell application. The membranes were characterized by the measurements of the water content, contact angle, FTIR spectra, thermal gravimetric analysis, ion exchange capacity, proton conductivity, methanol permeability and elastic modulus. The existence of hydrophilic moieties in the impregnated membranes was confirmed by contact angle and FTIR measurements. The impregnated PVA/PSSAMA(90:10) membrane exhibited a higher ion exchange capacity (1.2 meq./g dry membrane) than Nafion membrane (0.91 meq./g dry membrane). Through the elastic modulus measurement, the dimensional stability of the resulting membranes was expected to increase higher than the polyethylene membranes. The methanol crossover and water content decreased even if the PSSA-MA content increased due to the reduction of the free volume.

• Journal of Energy Engineering
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• v.29 no.2
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• pp.1-9
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• 2020

In recent days, fuel cell has received attention from the world as an alternative power source to hydrocarbon used in automobile engines. With the industrial advances of fuel cell, There have been a lot of researches actively conducted to find a way of generating hydrogen. Among many hydrogen production methods, Solid Oxide Electrolysis Cell(SOEC) is not only a basic way but also environment-friendly method to produce hydrogen gas. Solid Oxide Electrolysis Cell has lower electrical energy demands and high thermal efficiency since it is possible to operate under high temperature and high pressure conditions. For these reasons, experimental researches as well as studies on numerical modeling for Solid Oxide Electrolysis Cell have been under way. However, studies on numerical modeling are relatively less enough than experimental accomplishments and have limited performance prediction, which mostly is considered as a result from inadequate effects of electrochemical properties by temperature and pressure. In this study, various experimental studies of commercial Membrane Electrode Assembly (MEA) composed of Ni-YSZ (40wt%, Ni-60 wt% YSZ)/8-YSZ (TOSOH, TZ8Y)/LSM (La_0.9Sr_0.1MnO₃) was utilized for improving effectiveness of SOEC model. After numerically analyzing effects of electrochemical properties according to operating temperature, causing the largest deviation between experiments and simulation are that Charge Transfer Coefficient (CTC), exchange current density, diffusion coefficient, electrical conductivity in SOEC. Analyzing temperature effect on parameter used in overpotential model is conducted for modeling of SOEC. cross-validation method is adopted for application of various MEA and evaluating feasibility of model. As a result, the study confirm that the numerical model of SOEC based on structured process of effectiveness evaluation makes performance prediction better.