• Transactions on Electrical and Electronic Materials
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• v.6 no.4
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• pp.169-172
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• 2005

[ $Y_2O_3:Eu$ ] powder was synthesized using a solution-combustion method by dissolving $(CH_3CO_2)_3Y$ and $(CH_3CO_2)_3$ Eu in methyl-alcohol solution. Results from X-ray diffractometery (XRD), thermogravimetry (TG)-differential thermal analysis (DTA) show that $Y_2O_3:Eu$ crystallizes completely when the dry powder is sintered at $500^{\circ}C$. The investigated optical properties were the photoluminescence emission spectra, the excitation spectra and luminescence decay curve. Europium (Eu) concentration had no observable effect on the optical spectrum which depended on the emission intensity. The mean lifetime of synthesized phosphors was $2.3\~2.6 ms$.

• Journal of the Korean Wood Science and Technology
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• v.45 no.6
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• pp.671-681
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• 2017

Oil palm trunk (OPT) is a potential source of biomass for the production of biopellet. In the present research, biopellet were prepared from the meristem part of 25 years old OPT with various percentages of its bark (0, 10, and 30%). The highest biopellet durability was found for biopellet produced at $130^{\circ}C$ of pelletizing temperature with 30% bark content. Scanning electron microscopy (SEM) of biopellet showed the weak of particle bonding due to the low pelletizing pressure. The moisture content, unit density, ash content, and caloric value of OPT-based pellets were 3.55-5.35%, $525.56-855.23kg/m^3$, 2.76-3.44%, and 17.89-19.14 MJ/kg, respectively. The combustion profiles obtained by thermogravimetric analysis (TGA) seemed to be unaffected by the bark content on. Differential thermal analysis of TGA curve indicated different pyrolysis characteristic of hemicellulose, cellulose, and lignin.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.996-1000
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• 2002

A porous tube, comprised of a resin-coated woven fabric has recently been used as an effective component for use in intake systems of internal combustion engines to reduce the intake roaring. For the prediction of the acoustic performance of an engine intake system with a porous woven hose, the acoustic wall impedance of the hose must be known. Because of its peculiar acoustical and structural characteristics, the accurate measurement of the wall impedance ofa porous woven hose is not easy. A new measurement technique is proposed herein, that is valid over the low to mid frequency ranges. The acoustics impedance is inversely estimated from an overdetermined set of measured pressure transmission coefficients for specimens of different lengths and the reflection coefficient of end termination. The method involves only one measurement, and, as a result, it is very simple. The measured TL for samples with arbitrary conditions, arbitrary porous frequency, arbitrary length, and arbitrary mean flow condition, are in reasonably good agreement with values predicted from curve-fitted impedance data.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.53-59
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• 2019

LIBS plug, a simplified laser-induced breakdown spectroscopy(LIBS) device with the purpose of measuring the fuel distribution inside the combustion chamber, was developed and manufactured. The LIBS plug receives only two wavelengths (H:656.3 nm, O: 777 nm) that are closely related to the equivalence ratio in the overall spectrum. The calibration curve between the signal of the LIBS plug and the equivalence ratio was constructed, and the fuel distribution of gasoline-air and LPG-air mixtures was measured using the LIBS plug.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.99-107
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• 1998

This dissertationhas confirmed the non-flam mability of cast mold transformer that is increasingly used lately. As a research progress, the investigation has been performed on the installation status and each line of the subway system which have the most mold transformer accidents, and the impediment status of the transformer for rectifier and the high-voltage distribution transformer per each manufacturer. Then, a high voltage mold of the actual mold transformer has been installed in the horiwntal heating furnace and the heat has been applied by the standard heating temperature curve of KSF 2257(Fireproof testing meth od of the construction structures: 1993). Accordingly, the combustibility of the mold transformer based on the test results has been found that 78 minutes has been required for the complete burning per the KSF 2257 combustion test curve and that, after stopping the heat application of the horizontal furnace after ignition, the flame progress has not been made but shown as the self-extinguishing characteristics when the flame progress has been checked. Thus, the non-flammability and self-extinguishability of the mold transformer have been confirmed. The result of this dissertation has indicated that the accident involving mold transformer has been progressed and expanded by the dielectric breakdown or void due to the crack in the mold rather than a fire accident caused by a short-circuit or an overload.r an overload.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.217-222
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• 2006

Internal combustion engine is the main source of environmental pollutants and therefore advanced technology is required to reduce harmful elements from the exhaust gases all over the world. Especially, when the exhaust gas is released front the automotive muffler, exhaust noise has many bad influence on the surrounding environment. In order to reduce the exhaust noise, it is necessary that automotive muffler must be designed for best exhaust efficiency. The sound insulation room was installed for the analysis of an acoustics characteristics of the noise from automotive muffler, in this study. Exhaust gas noise, noise distribution characteristics, pressure and temperature of exhaust gas were investigated with the change of annulus temperature of air cooled annulus automotive muffler and cooled annulus automotive muffler. The following results were obtained with this study. From the frequency analysis of automotive muffler, high noise distribution was observed in the range $100{\sim}2000Hz$. It means that the noise in this range has an dominate influence for the overall noise. Noise reduction of automotive muffler was affected by the temperature of annulus. It is caused the result that the high temperature and pressure of exhaust gas are changed lower by the drop of annulus temperature. The tendencies of noise, the temperature and pressure of exhaust gas are similar to the performance curve of engine. Exhaust gas pressure is determined by the r.p.m. of engine and affected by the cooling performance of automotive muffler.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.200-207
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• 1993

A methanol reformer was designed and fabricated using a CuO-ZnO low temperature shift catalyst, and its operation characteristics have been studied for the phosphoric acid fuel cell (PAFC) power generation system. The type of reactor was annular Methanol was consumed both for heating and for reforming fuel. Contents of carbon monoxide produced from the reformer increased as the reaction temperatures increased, but decreased as the mole ratios of water to methanol(H$_2$O/CH$_3$OH) increased. At steady state operating conditional, temperature profile of the catalytic reactor of the reformer was well coincide with the model equation, and it took 50 minutes from start to the rated condition of the reformer. When the system was operated at 4/4 and 1/4 of load, thermal efficiencies of the system were 72.3% and 77%, respectively. When the PAFC system was operated with reformed gas in the range of 62 V-37.6 V and 0-147 A, the trend of I-V curve showed a typical fuel tell characteristic. At steady state condition, the flow rates of reforming and combustion methanol were 88.1 mol/h and 50.1 mol/h, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.11 no.1 s.22
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• pp.53-59
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• 2005

It is very dongerous for ship‘s fire which occurs from navigating because of it will not be able to expect fire fighting from land so that handle with the oneself to control. Additionally, in the case of passenger ship is more serious for the reason of not only the property damage but also large life accident can be occurred continuously. When the fire occurs, the many smoke to occur simultaneously as well as the heat from combustion process and the poisonous smoke is brought the life damage as the death from suffocation The purpose of this study is to examine the smoke movement characteristics in the ship's indoor spaces with fire size and location An experimental study was carried out with two sized of fires and three typed of fire source locations. As the results, the smoke and heat diffusion characteristics Ms been showed the most quick rise curve in the case of comer type fire.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.609-619
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• 2015

A preprocessing scheme utilizing multi-division of the ROI (region of interest) in a chemiluminescence image during inversion is proposed. The resulting inverted image shows the flame's structure, which can be useful for studying combustion instability. The flame structure is often quantitatively visualized with PLIF (planar laser-induced fluorescence) images as well. The chemiluminescence image, which is a line-integral of the flame, needs to be preprocessed before inversion, mainly due to the inherent noise and the assumption of axisymmetry during the inversion. The feasibility of the multi-division preprocessing technique has been tested with experimentally-obtained OH PLIF and $OH^*$ chemiluminescence images of jet and swirl-stabilized flames burning substitute natural gas (SNG). It turns out that the technique outperforms two conventional methods, specifically, the technique without preprocessing and the one with uni-division, reconstructing the SNG flame structures much better than its two counterparts when compared using corresponding OH PLIF images. The characteristics of the optimum degree of polynomials to be applied for curve-fitting of the flame region data for the multi-division method involving two flames has also been investigated.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.167-173
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• 2005

It is very dangerous for ship‘s fire which occurs from navigating because of it will not be able to expect fire fighting from land so that handle with the oneself to control. Additionally, in the case of passenger ship is more serious for the reason of not only the properly damage but also large life accident can be occurred continuously. When the fire occurs, the many smoke to occur simultaneously as well as the heat from combustion process and the poisonous smoke is brought the life damage as the death from suffocation. The purpose of this study is to examine the smoke movement characteristics in the ship's indoor spaces with fire size and location An experimental study was carried out with two sized of fires and three typed of fire source locations. As the result of it, the smoke and heat diffusion characteristics has been showed the most quick rise curve in the case of comer type fire.