• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.289-301
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• 1995

The effect of Air/$C_3H_8$ gas addition on the compound layer growth of steels nitrocarburised in $NH_3+Air+C_3H_8$ mixed gas atmospheres was investigated. It is considered that amount of residual $NH_3$ was varied according to alternation of Air/$C_3H_8$ mixing ratio and volume content. The compound layer formed from nitrocarburising was composed of ${\varepsilon}-Fe_{2-3}$(C, N) and ${\gamma}^{\prime}-Fe_4$(C, N). According as Air/$C_3H_8$ mixing ratio increased, the superficial content of ${\gamma}^{\prime}-Fe_4$(C, N) within the compound layer was increased, at the same time the growth rate of compound layer and porous layer was increased. In the case of alloy steel at the fixed gas composition, the growth rate of compound layer and porous layer was worse than carbon steel and compound layer phase composition structure primarily consisted of E phase. As the carbon content of materials was increasing in the given gas atmospheres, the growth rate of compound layer and porous layer was increased and the superficial content of ${\varepsilon}-Fe_{2-3}$(C, N) within the compound layer was increased.

• Environmental Engineering Research
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• v.13 no.4
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• pp.177-183
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• 2008

Ex-situ reductive dechlorination of carbon tetrachloride (CT) by iron sulfide in a batch reactor was characterized in this study. Reactor scaled-up by 3.5 L was used to investigate the effect of reductant concentration on removal efficiency and process optimization for ex-situ degradation. The experiment was conducted by using both liquid-phase and gas-phase volume at pH 8.5 in anaerobic condition. For 1 mM of initial CT concentration, the removal of the target compound was 98.9% at 6.0 g/L iron sulfide. Process optimization for ex-situ treatment was performed by checking the effect of transition metal and mixing time on synthesizing iron sulfide solution, and by determining of the regeneration time. The effect of Co(II) as transition metal was shown that the reaction rate was slightly improved but the improvement was not that outstanding. The result of determination on the regeneration time indicated that regenerating reductant capacity after $1^{st}$ treatment of target compound was needed. Due to the high removal rates of CT, ex-situ reductive dechlorination in batch reactor can be used for basic treatment for the chlorinated compounds.

• Journal of Environmental Science International
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• v.25 no.3
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• pp.417-424
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• 2016

The objective of this study was to evaluate the microwave drying characteristics of mixtures of chemical wastewater sludge (70~90%) and anthracite coal (10~30%) with respect to physical and economic factors such as mass, volume reduction, moisture content, drying rate and heating value when the wastes were dried at different weight mixing ratio and for different microwave irradiation time. The drying process were carried out in a microwave oven, the combined drying process with a 2,450 MHz frequency and 1 kW of power. Maximum dry rates per unit area on the microwave drying of mixtures with chemical wastewater sludge and anthracite coal were $35.5kg\;H_2O/m^2{\cdot}hr$ for Cs90-Ac10; $40.1kg\;H_2O/m^2{\cdot}hr$ for Cs80-Ac20 and $35.0kg\;H_2O/m^2{\cdot}hr$ for Cs70-Ac30. The result clearly indicated that moisture can be effectively and inexpensively removed from the wastes through use of the microwave drying process.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3427-3432
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• 2014

This study introduces a new method of combining Imaging Differential Optical Absorption Spectroscopy (Imaging-DOAS) data and plume dispersion formulas for power plant emissions to determine the three-dimensional structure of a dispersing pollution plume and the spatial distributions of trace gas volume mixing ratios (VMRs) under conditions of negligible water droplet and aerosol effects on radiative transfer within the plume. This novel remote-sensing method, applied to a power plant stack plume, was used to calculate the two-dimensional distributions of sulfur dioxide ($SO_2$) and nitrogen dioxide ($NO_2$) VMRs in stack emissions for the first time. High $SO_2$ VMRs were observed only near the emission source, whereas high $NO_2$ VMRs were observed at locations several hundreds of meters away from the initial emission. The results of this study demonstrate the capability of this new method as a tool for estimating plume dimensions and trace gas VMRs in power plant emissions.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.676-683
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• 2003

A laboratory experiment using artificial fracture rocks was used to understand the 3-dimensional dispersion of a tracer and the mixing process in a fractured network. In this experiment, 12cm polystyrene foam cubes with two electrodes for monitoring electric conductivity (EC) were used as artificial fractured rocks. Distilled water with 0.5mS/m was used as a tracer in water with 35mS/m and the difference of EC between the tracer and the water was monitored by a multipoint simultaneous measurement system of electrical resistance. The results showed that even if the fracture arrangement pattern was not straight in the direction of the flow, the tracer did not diffuse along individual fractures and an oval tracer plume, which was the distribution of tracer concentrations, tended to be form in the direction of the flow. The vertical cross section of the tracer distribution showed small diffusivity in the vertical direction. The calculated total tracer volume passing through each measurement point in the horizontal cross section showed while that the solute passed through measurement points near the direction of hydraulic gradient and in other directions, the passed tracer volumes were small. Using Peclet number as a criterion, it was found that the mass distribution at the fracture intersection was controlled in the stage of transition between the complete mixing model and the streamline routing model.

• Journal of ILASS-Korea
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• v.21 no.1
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• pp.29-36
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• 2016

The effect of high ambient temperature and pressure conditions on the combustion performance of n-butanol, n-heptane and its mixing fuel (BH 20) were studied in this work. To reveal this, the closed homogeneous reactor model applied and 1000-1200 K of the initial temperature, 20-30 atm of initial pressure and 1.0 of equivalence ratio were set to numerical analysis. It was found that the results of combustion temperature was increased and the ignition delay was decreased when the ambient conditions were elevated since the combustion reactivity increased at the high ambient conditions. On the contrary, under the low combustion temperature condition, the combustion pressure was more influenced by the ambient temperature in the same ambient conditions. In addition, the total mass and the mass density of tested fuels were influenced by the ambient pressure and temperature. Also, soot generation of mixing fuel was decreased than n-heptane fuel due to the oxygen content of n-butanol fuel.

• Korean Journal of Materials Research
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• v.23 no.11
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• pp.625-630
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• 2013

In this study, intermediate-mixed powders were prepared by loading zirconia powders initially in a ball-mill jar and loading alumina powders afterward; the initial-mixed powders were produced by loading zirconia and alumina powders together in the ball-mill jar. The effect of such differences in mixing method on the mechanical properties was investigated. In intermediate-mixed powders, the volume fraction of large particles slightly increased and, simultaneously, zirconia particles formed agglomerates that, due to early ball-mill loading of the zirconia powders only, were more dispersed than were the initial-mixed powders. For the intermediate-mixed powders, zirconia agglomerates were destroyed more quickly than were initial-mixed powders, so the number of dispersed zirconia particles rose and the inhibitory effect of densification due to the addition of a second phase was more obvious. In the microstructure of intermediate-mixed powders, zirconia grains were homogeneously dispersed and grain growth by coalescence was found to occur with increasing sintering temperature. For the initial-mixed powders, large zirconia grains formed by localized early-densification on the inside contacts of some zirconia agglomerates were observed in the early stages of sintering. The intermediate-mixed powders had slightly lower hardness values as a whole but higher fracture toughness compared to that of the initial-mixed powders.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.1
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• pp.65-82
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• 2018

With the significant increase in spent ion-exchange resin generation, to meet the requirements of Waste Acceptance Criteria (WAC) of the Wolsong disposal facility in Korea, blending is considered as a method for enhancing disposal options for intermediate level waste from nuclear reactors. A mass balance formula approach was used to enable blending process with an appropriate mixing ratio. As a result, it is estimated around 44.3% of high activity spent resins can be blended with the overall volume of low activity spent resins at a 1:7.18 conservative blending ratio. In contrast, the reduction of high activity spent resins is considered a positive solution in reducing the amount of spent resins stored. In an economic study, the blending process has been proven to lower the disposal cost by 10% compared to current APR1400 treatment. Prior to commencing use of this blending method in Korea, coordinated discussion, and safety and health assessment should be undertaken to investigate the feasibility of fitting this blending method to national policy as a means of waste predisposal processing and management in the future.

• Journal of ILASS-Korea
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• v.17 no.3
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• pp.121-127
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• 2012

The study is to investigate the mixing stability, fuel properties, and macroscopic spray characteristics of diesel-gasoline blended fuels in a common-rail injection system of a diesel engine. The test fuels were mixed diesel with gasoline fuel, which were based volume fraction of gasoline from 0 to 100% in 20% intervals. In order to analyze the blended effect of gasoline to diesel fuel, the properties of test fuels such as density, viscosity, and surface tension were measured. In addition, the spray behavior characteristics were studied by investigating the spray tip penetration and spray angle using a spray images through a spray visualization system. It was revealed that the density, kinematic viscosity and surface tension of diesel-gasoline blending fuels were decreased with the increase of gasoline fuel. The injection quantity of test fuels were almost similar level at short energizing duration condition. On the other hand, the increase of energizing duration shows the decrease of injection quantity compared to short energizing duration. The test blending fuels have similar growth in Spray tip penetration and Spray cone angle.

• Geomechanics and Engineering
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• v.6 no.3
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• pp.249-262
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• 2014

Tire chips and tire chips-soil mixtures can be used as alternative fill material in many civil engineering applications. In this study, the potential benefits of using tire chips as lightweight material to improve the bearing capacity and the settlement behavior of sand slope was investigated experimentally. For this aim, a series of direct shear and model loading tests were conducted. In direct shear tests, the effect of contents of the tire chips on the shear strength parameters of sand was investigated. Different mixing ratios of 0, 5, 10, 15 and 20% by volume were used and the optimum mixing ratio was obtained. Then, laboratory model tests were performed on a model strip footing on sand slope reinforced with randomly distributed tire chips. The loading tests were carried out on sand slope with relative density of 65% and the slope angle of $30^{\circ}C$. In the loading tests the percentage of tire chips to sand was taken as same as in direct shear tests. The results indicated that at the same loading level the settlement of strip footing on sand-tire chips mixture was about 30% less than in the case of pure sand. Addition of tire chips to sand increases BCR (bearing capacity ratio) from 1.17 to 1.88 with respect to tire chips content. The maximum BCR is attained at tire chips content of 10%.