• Journal of the Korean Geotechnical Society
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• v.34 no.6
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• pp.17-24
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• 2018

In this study, static load test and dynamic load test were performed to evaluate pile-filling material (ZA-Soil) of soil-cement injected precast pile method which was developed by using the ash of circulating fluidized boiler as a stimulant for alkali activation reaction of blast furnace slag. As a result of the static load test, the allowable bearing capacity of pile was 1,350 kN, which was the same as the result of using ordinary portland cement. And total settlement was 6.97 mm, and net settlement was 1.48 mm. These are similar to the total settlement, 7.825 mm, and net settlement, 2.005 mm of ordinary portland cement. As a result of the dynamic load test and CAPWAP analysis, the skin friction was 375.0 kN, the end bearing capacity was 3,045.9 kN, and the allowable bearing capacity was 1,368.36 kN. These results are similar to the results of using ordinary portland cement as pile-filling material.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.364-371
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• 2015

For the cost down of polymer concrete, It is very important to reduce the use amount of polymer binder, which occupies most of the production cost of polymer concrete. Fly ash and atomizing reduction steel slag are spherical materials obtained from industrial by-products. Spherical atomizing reduction steel slag was manufactured using steel slag from reduction process of ladle furnace by atomizing technology. To investigate the physical properties of polymer concrete, polymer concrete specimens were prepared with the various proportions of polymer binder and replacement ratios of atomizing steel slag. Results showed that compressive and flexural strengths of the specimens were remarkably increased with the addition amount of polymer binder and the replacement ratios of atomizing steel slag. In the hot water resistance test, compressive strength, flexural strength, bulk density and average pore diameter decreased but total pore volume and pore diameter increased. We found that polymer concrete developed in this study reduced the amount of polymer binder by 18.2% compared to the conventional product because of the remarkable improvement of workability of polymer concrete using spherical fly ash and atomizing reduction steel slag instead of calcium carbonate (filler) and river sand (fine aggregate).

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.631-640
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• 2018

The application of an oxy-combustion circulating fluidized bed combustor (Oxy-CFBC) for low grade coals has recently developed in the world to meet the continuous increase of energy demand and to achieve the reduction of greenhouse gases. Since demo plants for Oxy-CFBC have been developed, the combustion properties of Oxy-CFBC in various operation conditions, such as gas flow rates, combustion temperature, fuel, and so on, should be investigated to develop design criteria for a commercial Oxy-CFBC. In this study, a computational simulation tool for Oxy-CFBC was developed on the basis of the IEA-CFBC (International Energy Agency Circulating Fluidized Bed Combustor) model. Simulation was performed under various conditions such as reaction temperature ($800^{\circ}C{\sim}900^{\circ}C$), oxygen contents (21%~41%), coal feeding rate, Ca/S mole ratio (1.5~4.0), and so on. Simulation results show that the combustion furnace temperature is higher in oxy 1 than air fired. However, the temperature gradient tended to decrease with increasing oxy mixing percent. In case of $SO_x$, the higher the Ca/S mole ratio and oxy mixing percent, the higher the desulfurization efficiency.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.10
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• pp.427-436
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• 2013

In this paper, a method of moving path control of an automatic guided vehicle in an indoor environment through recognition of marker images using vision sensors is presented. The existing AGV moving control system using infrared-ray sensors and landmarks have faced at two critical problems. Since there are many windows in a crematorium, they are going to let in too much sunlight in the main hall which is the moving area of AGVs. Sunlight affects the correct recognition of landmarks due to refraction and/or reflection of sunlight. The second one is that a crematorium has a narrow indoor environment compared to typical industrial fields. Particularly when an AVG changes its direction to enter the designated furnace the information provided by guided sensors cannot be utilized to estimate its location because the rotating space is too narrow to get them. To resolve the occurrences of such circumstances that cannot access sensing data in a WSN environment, a relative distance from marker to an AGV will be used as fingerprinting used for location estimation. Compared to the existing fingerprinting method which uses RSS, our proposed method may result in a higher reliable estimation of location. Our experimental results show that the proposed method proves the correctness and applicability. In addition, our proposed approach will be applied to the AGV system in the crematorium so that it can transport a dead body safely from the loading place to its rightful destination.

• Journal of the Korea Institute of Building Construction
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• v.16 no.2
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• pp.97-105
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• 2016

Recently, application case of the ultra rapid hardening concrete-polymer composite(URHCPC) are increasing to repair for the deterioration of pavement. But it is a major disadvantage that the main material is expensive and has environmental load. For these reasons, the development of the economic, eco-friendly materials is needed. Calcium Aluminate Composite (CAC), produced by rapid cooling of atomizing method with molten ladle furnace slag, is a material capable of improving the economic feasibility and reducing the environmental load of URHCPC. In this paper, the properties of CAC and gypsum mixed CAC (GC) as alternative materials of RSC according to the types of polymer dispersion were studied. The results were as follows; compressive strength, tensile strength, flexural strength, bonding strength and modulus of elasticity of the composites using CAC or GC showed higher values than those of plain proportion in 3 hour. In later age, they were at the same level as the general proportions. URHCPC using BPD as polymer dispersion had superior strength properties generally. But modulus of elasticity was the same level as the case of using a SBR latex. According to these results, CAC or GC can partially substituted for RSC to product the URHCPC. When URHCPC uses the BPD as the polymer dispersion, it can be improved performance.

• Journal of the Korean Chemical Society
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• v.40 no.12
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• pp.724-732
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• 1996

The organic precipitate flotation using Cu(II)-pyrrolidinedithiocarbamate complex as a coprecipitant was studied for the preconcentration and determination of trace Cd, Pb, Bi and Co in several water samples. Experimental conditions such as pH of solution, amounts of Cu(II) and ammonium pyrrolidinedithiocarbamate(APDC), stirring time, the type and amount of surfactant, etc. were optimized for the effective flotation of analytes. After 3.0 mL of 1,000 ${\mu}g/mL$ Cu(II) solution was added to 1.00 L water sample, the pH of the solution was adjusted to 2.5 with HNO3 solution. Trace amounts of analytes were coprecipitated by adding 2.0% APDC solution. And the precipitates were flotated onto the surface of solution with the aid of nitrogen gas and sodium lauryl sulfate. The floats were collected from mother liquor, and filtered through the micropore glass filter by suction. The precipitates were dissolved with 4 mL conc. HNO3, and then diluted to 25.00 mL with deionized water. The analytes were determined by graphite furnace atomic absorption spectrophotometry. This flotation technique was applied to the analysis of some water samples, and the 90 to 120% of recoveries were obtained from the spiked samples, this procedure could be concluded to be simple and applicable for the trace element analysis in various kinds of water.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.475-481
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• 2013

Although the lightly burnt MgO at $850{\sim}1000^{\circ}C$ has expansibility, it does not lead to unsound concrete. The expansion of MgO could compensate for shrinkage of concrete for a long-term, because the hydration of MgO occurs at a slow pace. Recently, the study and application of mineral admixture such as fly ash and blast furnace slag have increased for the hydration heat reduction, durability improvement, and reducing $CO_2$ emission in the construction industry. Thus, it is necessary to research on the concrete that contains both a mineral admixture and MgO as an expansion agent. This study investigates fundamental properties of fly ash concrete with lightly burnt MgO through various experiments. The adiabatic temperature test results showed that the fly ash concrete with MgO of the 5% replacement ratio had the slower pace of the temperature rise and the lower final temperature than the fly ash concrete. The influences of MgO on long-term compressive strength varied depending on water-binder ratio, and the long-term length change test results indicated the expansion effects of the FA concrete containing MgO.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.259-267
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• 2010

In this study, the effect of particle size on the combustion characteristics of pulverized sub-bituminous coal was experimentally investigated. A laminar-flow-entrained reactor was designed and implemented to realize the desired heating ratio and temperature corresponding to the combustion atmosphere of a pulverized-coal-fueled furnace. The flame length and structure of burning particles according to different sizes were investigated. Coal combustion processes were clearly distinguished by direct visual observation of the flame structure. The onset point of volatile ignition is greatly affected by changes in the particle size, and the burning time of the volatiles is least affected by changes in the particle size. The length and instability of char flame also increase with the increase of the particle size. However, the char consumption rate within the residential time remains nearly constant.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.1-11
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• 2005

The stoichiometric mixture of evaporating materials for the $CuInSe_2$ single crystal thin film was prepared from horizontal furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CuInSe_2$, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.783\;{\AA}$ and $11.621\;{\AA}$, respectively. To obtain the $CuInSe_2$ single crystal thin film, $CuInSe_2$ mixed crystal was deposited on throughly etched GaAs(100) by the HWE(Hot Wall Epitaxy) system. The source and substrate temperature were $620^{\circ}C$ and $410^{\circ}C$ respectively. The crystalline structure of $CuInSe_2$ single crystal thin film was investigated by the double crystal X-ray diffraction(DCXD). Hall effect on this sample was measured by the method of Van der Pauw and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by impurity scattering in the temperature range 30 K to 100 K and by lattice scattering in the temperature range 100 K to 293 K. The temperature dependence of the energy band gap of the $CuInSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.1851\;eV-(8.99{\times}10^{-4}\;eV/K)T^2/(T+153\;K)$. The open-circuit voltage, short current density, fill factor, and conversion efficiency of $n-CdS/p-CuGaSe_2$ heterojunction solar cells under $80\;mW/cm^2$ illumination were found to be 0.51V, $29.3\;mA/cm^2$, 0.76 and 14.3 %, respectively.

• Journal of the Korean Solar Energy Society
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• v.38 no.1
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• pp.25-36
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• 2018

The stoichiometric mixture of evaporating materials for the $CaAl_2Se_4$: Co single crystal thin film was prepared from horizontal furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CaAl_2Se_4$, it was found orthorhomic structure whose lattice constant $a_0$, $b_0$ and $c_0$ were 6.4818, $11.1310{\AA}$ and $11.2443{\AA}$, respectively. To obtain the $CaAl_2Se_4$: Co single crystal thin film, $CaAl_2Se_4$: Co mixed crystal was deposited on throughly etched Si (100) by the HWE (Hot Wall Epitaxy) system. The source and substrate temperature were $600^{\circ}C$ and $440^{\circ}C$ respectively. The crystalline structure of $CaAl_2Se_4$: Co single crystal thin film was investigated by the double crystal X-ray diffraction (DCXD). Hall effect on this sample was measured by the method of Van der Pauw and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by impurity scattering in the temperature range 30 K to 100 K and by lattice scattering in the temperature range 100 K to 293 K. The temperature dependence of the energy band gap of the $CaAl_2Se_4$: Co obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=3.8239eV-(4.9823{\times}10^{-3}eV/K)T_2/(T+559K)$. The open-circuit voltage, short current density, fill factor, and conversion efficiency of $p-Si/p-CaAl_2Se_4$: Co heterojunction solar cells under $80mW/cm^2$ illumination were found to be 0.42 V, $25.3mA/cm^2$, 0.75 and 9.96%, respectively.