• Journal of Energy Engineering
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• v.20 no.1
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• pp.13-20
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• 2011

The high fuel flexibility of Micro Gas Turbine(MGT) has boosted their use in a wide variety of applications. Recently, the demand for biogas generated from the digestion of organic wastes and landfill as a fuel for gas turbines has increased. We researched the influence of firing landfill gas(LFG) on the performance and operating characteristics of a micro gas turbine combined heat and power system. $CH_4$ and $CO_2$ simultaneous recovery process has been developed for field plant scale to provide an isothermal, low operating cost method for carrying out the contaminants removal in Land Fill Gas(LFG) by liquid phase catalyst for introduce into the green house for the purpose of $CO_2$ rich cultivation of the plants. Methane purification and carbon dioxide stripping by muti panel autocirculation bubble lift column reactor utilizing Fe-EDTA was conducted for evaluate optimum conditions for land fill gas. Based on inflow rate of LFG as 0.207 $m^3$/min, 5.5 kg/$cm^2$, we designed reactor system for 70% $CH_4$ and 27% $CO_2$ gas introduce into MGT system with $H_2S$ 99% removal efficiency. A green house designed for four different carbon dioxide concentration from ambient air to 1500 ppm by utilizing the exhaust gas and hot water from MGT system.

• Korean Journal of Construction Engineering and Management
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• v.13 no.6
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• pp.94-106
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• 2012

In recent years, the risks and uncertainties associated with mixed used development in urban regeneration projects which have actively been implemented at home and abroad have been on the rise due to the uncertainties of the initial business plan, difficulty of financing, increase in total cost and schedule delay. To cope with rapid social and economic changes and optimize benefits, a risk-based configuration management process that considers life cycle is required, along with accurate planning in the early stage of the business. In addition, it is necessary to prepare measures that can respond to the evaluation and measurement of the configuration factors in relation to the business process. However, the focus of previous studies on configuration management in the field of construction was mainly on humanities and the sociological aspects such as organization, leadership, ideology and similar concepts. There has been limited research on the process and measurement and evaluation methods for configuration factors required in decision-making on the risks and changes that can occur in the actual project implementation phase. Accordingly, in this study, we defined risk-based configuration factors and developed a process and MECA/3DAM/CII methodology to measure and evaluate these factors so as to carry out systematic configuration management of mixed used development in urban regeneration projects.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.139-146
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• 2004

A 2D/3D complex optical system and its vision inspection algerian is proposed and implemented as a single probe system for high speed, precise vision inspection of the solder pastes. One pass un length labeling algorithm is proposed instead of the conventional two pass labeling algorithm for fast extraction of the 2D shape of the solder paste image from the recent line-scan camera as well as the conventional area-scan camera, and the optical probe path generation is also proposed for the efficient 2D/3D inspection. The Moire interferometry-based phase shift algerian and its optical system implementation is introduced, instead of the conventional laser slit-beam method, for the high precision 3D vision inspection. All of the time-critical algorithms are MMX SIMD parallel-coded for further speedup. The proposed system is implemented for simultaneous 2D/3D inspection of 10mm${\times}$10mm FOV with resolutions of 10 ${\mu}{\textrm}{m}$ for both x, y axis and 1 ${\mu}{\textrm}{m}$ for z axis. Experiments conducted on several nBs show that the 2D/3D inspection of an FOV, excluding an image capturing, results in high speed of about 0.011sec/0.01sec, respectively, after image capturing, with $\pm$1${\mu}{\textrm}{m}$ height accuracy.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.5
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• pp.313-322
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• 2001

The effects of Zr/Ti concentration ratio in PLZT (10/y/z) thin films prepared by sol-gel method are investigated for the NVFRAM application. Rosette and pyrochlore phase are observed in PLZT (10/40/60) thin film and the (100) orientation, the grain size, and the surface roughness of PLZT thin films increase due to the increase of Ti amount in Zr/Ti concentration ratio. As Ti amount of Zr/Ti concentration ratio increases, the dielectric constants at 10KHz decrease from 600 to 400, while the loss tangents increase from 0.028 to 0.053 and the leakage current densities at 170 kY/cm decrease from 1.64$\times$10$^{-6}$ to 1.26$\times$10$^{-7}$ A/$\textrm{cm}^2$. In the results of hysteresis loops measured at $\pm$ 170 ㎸/cm, the remanent polarization and the coercive field increase from 6.62 to 12.86 $\mu$C/$\textrm{cm}^2$ and from 32.15 to 56.45 ㎸/cm, respectively, according to the change from 40/60 to 0/100 in Zr/Ti concentration ratio. Fatigue and retention properties also improve much as the Zr/Ti concentration ratio change from 40/60 to 0/100. After applying 10$^{9}$ square pulses with $\pm$5V, the remanent polarization of the PLZT (10/40/60) thin film decreases 50％ from the initial state while that of the PLZT (10/0/100) thin film decreases 30％. In the results of retention measurements of 10$^{5}$ s, the remanent polarization of the PLZT (10/0/100) thin film decreases only 11％ from the initial state, while that of the PLZT (10/40/60) thin film decreases 40%.

• Journal of the Korean GEO-environmental Society
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• v.17 no.2
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• pp.5-11
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• 2016

$MWCNT-TiO_2$ nano composites and $Ag-MWCNT-TiO_2$ nano composites were prepared from Multi-Walled Carbon NanoTube (MWCNT), titanium (IV) butoxide (TNB) solution and silver nitrate ($AgNO_3$) by the sol-gel method. The dispersion and structure of Ag in the synthesized composites was observed by Scanning Electron Microscopy (SEM) and Field Emission Transmission Electron Microscopy (FE-TEM). X-Ray Diffraction (XRD) patterns of the composites showed that the composites contained an anatase phase. The Energy Dispersive X-ray spectroscopy (EDX) showed the presence of C, O, Ti and Ag peaks. The $TiO_2$ particles were distributed uniformly in the MWCNT network, and Ag particles were virtually fixed on the surface of the tubes. Also decomposition of the methylene blue was investigated according to UV radiation times for study photocatalytic activity. $Ag-MWCNT-TiO_2$ nano composites show high photodegradation than $MWCNT-TiO_2$ nano composites. The results indicate that the high conductivity of Ag improved the photoactivity of the $MWCNT-TiO_2$ composite.

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.242-247
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• 2000

$Pb_{0.99}[(Zr_{0.6}Sn_{0.4})_{0.9}Ti_{0.1}]_{0.98}Nb_{0.02}O_3(PNZST)$ thin films were deposited by RF magnetron sputtering on $(La_{0.5}Sr_{0.5})CoO_3(LSCO)/Pt/Ti/SiO_2/Si$ substrate using a PNZST target with excess PbO of 10 mole%. The thin films deposited at substrate temperature of $500^{\circ}C$, and at RF power of 80W were crystallized to a perovskite phase after rapid thermal annealing(RTA). The thin films annealed at $650^{\circ}C$ for 10 seconds in air exhibited the good structures and electrical properties. The fabricated PNZST capacitor had a remanent polarization value of about $20\;{\mu}C/cm^2$ and coercive field of about 50 kV/cm. The reduction of the polarization after $2.2{\times}10^9$ switching cycles was less than 10%.

• Economic and Environmental Geology
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• v.38 no.2 s.171
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• pp.155-163
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• 2005

For an unbiased TF (Tansfer Function) estimations we investigate geomagnetic TF derived from ICHEON and YONGIN sites, employing RR (Remote Reference) and SNS (Signal Noise Separation) techniques. The Rh technique, which requires synchronized field variations recorded at a clean remote site, is a reliable method to minimize the bias of TF by uncorrelated noises in magnetic channels. Meanwhile, SNS technique based on the assumption of noise-free remote data can improve the signal-noise level by separating signal TF and noise TF, which is successfully applied to the environments with strong correlated noises. In this study, TF at YONGIN is analyzed using geomagnetic data from ICHEON site as a remote reference, which seem to have somewhat better data quality. The application of Rh technique reduces the bias of TF, which appears in single site robust estimation, and makes curves in the amplitude and phase of TF more smooth as frequency. Futhermore, in order to investigate noise source quantitatively, SNS technique is applied. The results of SNS suggest that dominant noise source seems to be located at western region of YONGIN. This noise source is considered to originate from railway system such as KTX and national subway. which passes through the west regions of YONGIN.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.420-426
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• 2017

Recently, solvent-resistant nanofiltration membranes have been studied for the separation of solvents or solutes using a molecular weight cut-off system of the polymer which is resistant to a specific solvent. Required conditions for these membranes must have are excellent physical properties and solvent resistance. Polybenzimidazole, which is known to be one of the most heat-resistant commercially available polymers, has an excellent inherent solvent resistance and it is even insoluble in stronger organic solvents when cross-linked. Therefore, in this study, the applicability of polybenzimidazole as a solvent resistant nanofiltration membrane was discussed. The membrane was fabricated using the non-solvent induced phase separation method and showed a suitable morphology as a nanofiltration membrane confirmed by field emission scanning electron microscopy. In addition, the permeance of the solvent in the presence or absence of cross-linking was investigated and the stability was also confirmed through long operation. The permeance test was carried out with five different solvents: water, ethanol, benzene, N, N-dimethylacetamide (DMAc) and n-methyl-2-pyrrolidone (NMP); each of the initial flux was $6500L/m^2h$ (water, 2 bar), $720L/m^2h$ (DMAc, 5 bar), $185L/m^2h$ (benzene, 5 bar), $132L/m^2h$ (NMP, 5 bar), $65L/m^2h$ (ethanol, 5 bar) and the pressure between 2 and 5 bar was applied depending on the type of membrane.

• Progress in Superconductivity
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• v.9 no.1
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• pp.68-73
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• 2007

We fabricated the in-situ $MgB_2$ wires using the powder-in-tube method and investigated the effects of sintering temperature and SiC contents on the microstructure and superconducting properties. Pure $MgB_2$ wires and 5, 10, 20 wt.% SiC doped $MgB_2$ wires were sintered at $600-1000^{\circ}C$ for 30 minutes in Ar atmosphere. We found that $MgB_2$ phase was mostly formed at the sintering temperature of $700^{\circ}C$ and above, and the critical temperature ($T_c$) increased with increasing sintering temperature. For the $MgB_2$ sintered at $850^{\circ}C$, the highest critical current density ($J_c$) was obtained to be $3.7{\times}10^5\;A/cm^2$ at 5 K and 1.6 T by a magnetic properties measurement system (MPMS). The addition of SiC to the $MgB_2$ wires changed microstructure and critical properties. SEM observation showed that the $MgB_2$ core had considerable micro-cracks in undoped wire and the density of micro-cracks decreased with increasing SiC contents. The critical temperature decreased as the SiC contents increased, on the other hand, the critical current density of SiC doped $MgB_2$ wires in high magnetic field was enhanced compared to that of undoped $MgB_2$ wires.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.651-656
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• 2005

Toluene, which is emitted from textile process, is considered as an important hazardous air pollutant. In this study, the catalytic activity of transition metal oxides(Cu, Mn, V, Cr, Co, Ni, Ce, Sn, Fe, Sr, Cs, Mo, La, W, Zn)/${\gamma}-Al_2O_3$ catalysts was investigated to carry out the complete oxidation of toluene. The metal catalysts were characterized by XRD-ray diffraction), FE-SEM(Field Emission Scanning Electron Micrograph), BET(Brunauer Emmett Teller) method and TPR(Temperature Programmed Reduction). Among the catalysts, Cu/${\gamma}-Al_2O_3$ was highly promising catalyst for the oxidation of toluene. From the BET results, it seems that the catalytic activity is not correlated to the specific surface area. XRD results indicated that most of catalysts exist as amorphous phase. From the FE-SEM results, it was observed that copper on ${\gamma}-Al_2O_3$ surface was well dispersed among catalysts. The catalytic activity for the toluene oxidation could be explained with that metal oxide catalyst was dispersed well over supports and was attributed to reduction activity in surface of catalysts.