• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.571-575
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• 2011

Graphite-based electrodes were prepared using synthetic graphite (MCMB 1028) or natural graphite (NG) powder using a dimensionally stable anode (DSA) as a substrate. Their electrochemical properties were investigated in vanadiumbased electrolytes to determine how to increase the durability and improve the energy efficiency of redox flow batteries. Cyclic voltammetry (CV) was performed in the voltage range of -0.7 V to 1.6 V vs. SCE at various scan rates to analyze the vanadium redox reaction. The graphite-based electrodes showed a fast redox reaction and good reversibility in a highly concentrated acidic electrolyte. The increased electrochemical activity of the NG-based electrode for the $V^{4+}/V^{5+}$ redox reaction can be attributed to the increased surface concentration of functional groups from the addition of conductive material that served as a catalyst. Therefore, it is expected that this electrode can be used to increase the power density and energy density of redox flow batteries.

• Journal of the Ergonomics Society of Korea
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• v.11 no.1
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• pp.31-38
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• 1992

The population of aged people in industries has been increased remarkably due to the decline of birth rates and the increase of average life span. Also, the current automation trends makes aged people to work easy in industries since automation technologies help them to avoid physically hard tasks. Therefore the evaluation of aged workers' adaptability would be an important research topic. In the study, the mean and standard deviation of the reaction time are calculated to see the differences with four lamps's types and ages. It is found that the mean reaction time and the standard deviation are increased with the the increase of age. The quantitative approach provides an important information to be used not only for the adaptability estimation of aged workers but also for the working capability qualification for re-employment.

• Journal of the Korean Society of Radiology
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• v.2 no.1
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• pp.31-34
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• 2008

The neutron capture spectrum for the light nuclide was very useful to study the nuclear structure. In the present study, the capture gamma-ray from the 27-keV resonance of $^{19}F(n,g)^{20}F$ reaction were measured with an anti-Compton NaI(Tl) spectrometer and the 3-MV Pelletron accelerator of the Research Laboratory for Nuclear Reactors at the Tokyo institute of technology. A neutron Time-of-Flight method was adopted with a 1.5 ns pulsed neutron source by the $^7Li(p,n)^7Be$ reaction. In the present experiment, a Teflon(($CF_2$)n) sample was used The sample was disk with a diameter of 90mm. The thickness of sample was determined so that reasonable counting rates could be obtained and the correction was not so large for the self-shielding and multiple scattering of neutrons in the sample, and was 5mm. The primary gamma-ray transitions were compared with previous measurement of Kenny.

• Journal of the Korean institute of surface engineering
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• v.9 no.2
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• pp.1-7
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• 1976

The dissolving and growth kinetics of intermetallic compounds for the reaction between solid iron and molten zinc were studied under nitorgen atmosphere over the temperature range between470$^{\circ}C$ and 680$^{\circ}C$. The rates of dissolution of solid iron into molten zinc were obtained under a static conditon, The amount of dissolution of sold iron and the growth of intermetalic compounds could be determined by means of microscopy. The thickness of intermetallic compound at a given temperature increases with increasing time, whereas for a given time decreases with increasing temperature . The rate of dissolution is controlled by the diffusion process of iron in the effective boundary layer of molten zinc over the temperature range 470$^{\circ}$-530$^{\circ}C$, 570$^{\circ}$-620$^{\circ}C$, and 650$^{\circ}$-665$^{\circ}C$, while by the surface reaction over the range 530$^{\circ}$-570$^{\circ}C$ and 620$^{\circ}$-650$^{\circ}C$.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.37-40
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• 2012

In an entrained flow coal gasifier, predicting the reaction behavior of pulverized coal particles requires detailed information on devolatilization, char gasification, gaseous reactions, turbulence and heat transfer. Among the input parameters, the rate of devolatilization and the composition of volatile species are difficult to determine by experiments due to a high pressure (~40 bar) and temperature (${\sim}1500^{\circ}C$). This study investigates the effect of devolatilization models on the reaction and heat transfer characteristics of a 300 MWe Shell coal gasifier. A simplified devolatilization model and advanced model based on Flashchain were evaluated, which had different volatiles composition and devolatilization rates. It was found that the tested models produce similar flow and reaction trends, but the simplified model slightly over-predict the temperature and wall heat flux near the coal inlets.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.121-127
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• 2006

It has become inevitable to search for alternative fuels due to severe energy crisis these days. Use of alternative fuels, which are typically of lower quality, tends to increase environmental pollution, including formation of nitrogen oxides (NOx). In this paper performance of vacuum residue has been investigated experimentally as well as numerically in typical operating conditions of a furnace. Heat release reaction is modeled as sequential steps of devolatilization, simplified gas phase reaction and char oxidation as that for pulverized coal. Thermal and fuel NOx are predicted by conditional estimation of elementary reaction rates and are compared against measured experimental data. On the overall reasonable agreement is achieved for spatial distributions of major species, temperature and NOx for all test cases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.2
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• pp.120-129
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• 1994

A numerical investigation has been carried out for the electrochemical reaction, mass and heat transfer characteristics of the Molten Carbonate Fuel Cell(MCFC) stack. The effects of cooling air channel and water gas shift reaction were taken into account. The current density distribution of electrodes, the molecular fractions of reactant gasses and three dimensional temperature distribution can be calculated and shown by several lines of equivalent values. The results have been compared with the existing ones, and reasonable agreement has been obtained. To examine the influence of changing parameters, such as the composition of reactant gases, the target average current density, the utilization of reactant gases, the cooling air inlet temperature and flow rates, the computer simulation has been done. The analysis method and computer program developed in this study will be greatly helpful to design and verify the optimum operating condition of MCFC stack.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.4
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• pp.257-262
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• 2007

Squid viscera oil was investigated by pretreatment method for enhancing the commercial value. Transeterification was performed to reduce rancidity of the oil, off-flavor was removed by using activated carbon adsorption. Analysis using ATD (Automatic Thermal Desorber) and GC/MG shows the efficacy of off-flavor removement. The rates of Transesterification employing inorganic catalyst and biocatalyst were tested, respectively. With stepwise addition of ethanol, the most efficiency of the reaction was achieved by inorganic catalyst. The efficiency of the reaction was estimated by acid value corresponding to rancidity of reaction product.

• KSBB Journal
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• v.8 no.4
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• pp.358-363
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• 1993

The effect of ultrasound on the acid hydrolysis of inulin was studied under significantly mild reaction conditions, at which sugar degradation products were not detected. Reaction conditions were i the range of 50~$60^{\circ}C$ and 0.1~0.3%(w/w) of HCl concentrations. The effects of reactor position inside water bath and mechanical agitation under ultrasound were investigated. The production rates of fructose with/without ultrasound irradiation were compared. The activation energies for both control and ultrasound reaction were the same, i. e., 25kca1/mo1, and ultrasound enhancement was average 22%.

• Advances in environmental research
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• v.1 no.3
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• pp.191-199
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• 2012

A kinetic study of the transesterification of soybean oil was conducted using microwaves under various temperatures, power densities, and reaction times. Results show that power density affects the kinetics and yield. The biodiesel yield increased with increasing microwave power density. The non-thermal effects of microwave irradiation on transesterification reactions were evaluated at a constant reaction temperature ($65^{\circ}C$) and power density (0.204 $Wg^{-1}$). Microwave irradiation was found to increase the reaction rates by 3.52-7.06 fold.