• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.2
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• pp.289-298
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• 2011

TMAH-based Py-MS has been investigated to apply for a real-time classification of biological agents in the field. Acquiring reproducible data from mass spectrometry is a key to biological detection in the field. Nevertheless, it has been little studied on what factors could affect to the reproducibility of the TMAH-based Py-MS spectrum patterns. Given the TMAH-based Py-MS applied to the field system, several factors which could affect to the reproducible pattern of TMAH-based Py-MS spectra are needed to be examined, including changes in TMAH injection volume, growth temperature for microorganism, and number of cells collected in pyrolyzer, and implication of stabilizer used for lyophilization. This study showed that the reproducibility of the spectrum patterns was significantly hindered by changes in TMAH concentration and cell number, and stabilizer implication but not by growth temperature. Among those at low TMAH concentration(0.015m) was not observed the significant alterations of the spectrum pattern even when its injection volume was changed, yet was in different cell numbers and stabilizer implication.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.93-93
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• 2009

In order to overcome the lack of reactivity with hydrogen gas ($H_2$) and utilize unique properties of Carbon Nano Tubes (CNTs) for the application to hydrogen sensors, there have been intensive works on the surface functionalization of CNTs with various types of nanoparticles including Pd. In the present work, we have investigated the effect of dendrimers and Pd nanoparticles to the hydrogen sensing properties of CNTs by comparing three types of samples: Pd/SWNTs (Sample I), Pd/dendrimer/SWNTs (Sample II) and heat-treated Pd/dendrimers/SWNTs (Sample III). As a result of IV measurement under the $H_2$ and air, sample I was found to have a high sensitivity (25%) to $H_2$, but to have a very slow response time (324 s) and recovery rate. On the other hand, Sample II was found to show much faster response time (3 s) and good recovery rate but lower sensitivity (8.6%) than Sample I which is due to induced dipole moments in the dendrimers. Interestingly, Sample III showed both fast response time (7 s) and high sensitivity (25%), indicating that the pyrolysis of the dendrimers during heat treatment which reduce the distance between the surface of the SWNTs and the functionalized Pd nanoparticles plays a key role in improving the sensitivity. The pyrolysis of the dendrimers in Pd nanoparticle-dendrimer-SWNTs was found to enable a significant electrical conductance modulation upon exposure to extremely low concentrations (10 ppm) of $H_2$ in air. Our results demonstrate that the Pd Nanoparticle-Grafted Single-Walled Carbon Nanotubes(SWNTs) with Dendrimers can be used to detect hydrogen, makingoutstanding properties such as fast response, and recovery time, high sensitivity, low detection limit at room temperature compared with other types of hydrogen sensors.

• Preventive Nutrition and Food Science
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• v.22 no.2
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• pp.131-137
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• 2017

Maximum production of isoquercetin and quercetin simultaneously from rutin by subcritical water hydrolysis (SWH) was optimized using the response surface methodology. Hydrolysis parameters such as temperature, time, and $CO_2$ pressure were selected as independent variables, and isoquercetin and quercetin yields were selected as dependent variables. The regression models of the yield of isoquercetin and quercetin were valid due to the high F-value and low P-value. Furthermore, the high regression coefficient indicated that the polynomial model equation provides a good approximation of experimental results. In maximum production of isoquercetin from rutin, the hydrolysis temperature was the major factor, and the temperature or time can be lower if the $CO_2$ pressure was increased high enough, thereby preventing the degradation of isoquercetin into quercetin. The yield of quercetin was considerably influenced by temperature instead of time and $CO_2$ pressure. The optimal condition for maximum production of isoquercetin and quercetin simultaneously was temperature of $171.4^{\circ}C$, time of 10.0 min, and $CO_2$ pressure of 11.0 MPa, where the predicted maximum yields of isoquercetin and quercetin were 13.7% and 53.3%, respectively. Hydrolysis temperature, time, and $CO_2$ pressure for maximum production of isoquercetin were lower than those of quercetin. Thermal degradation products such as protocatechuic acid and 2,5-dihydroxyacetophenone were observed due to pyrolysis at high temperature. It was concluded that rutin can be easily converted into isoquercetin and quercetin by SWH under $CO_2$ pressure, and this result can be applied for SWH of rutin-rich foodstuffs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.9
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• pp.1117-1123
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• 2004

The characteristics of soot near the soot inception point for an ethene-air flame was carried out in a WSR (well-stirred reactor). The new sampling tool like the temperature controlled filter system was introduced to minimize the condensation during sampling. The new analysis tools applied include the real time size distribution analysis with the Nano-DMA, particle size by transmission electron microscopy, C/H analysis, g filter analysis, and thermogravimetric analysis using both non-oxidative and oxidative pyrolysis. The WSR can generate young soot particles that can be collected and examined to gain insight into inception. For the current conditions, soot does not form for ${\Phi}$=1.9, inception occurs at or before ${\Phi}$=2.0, and inception combined with soot surface growth and/or coagulation occurs for ${\Phi}$=2.1. The filter samples for ${\Phi}$=1.9 are composed of volatile compounds that evolve at relatively low temperatures when heated in the presence or absence of O$_2$. The samples collected from the WSR at ${\Phi}$=2.0 and ${\Phi}$=2.1 are precursor-like in morphology and size. They have higher C/H ratios and lower organic percentages than precursor particles, but they are clearly not fully carbonized soot. The WSR PAH distribution is similar to that in young soot from inverse flames.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1298-1303
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• 2004

The characteristics of soot near the soot inception point for an ethene-air flame was carried out in a WSR (well-stirred reactor). The new sampling tool like the temperature controlled filter system was introduced to minimize the condensation during sampling. The new analysis tools applied include the real time size distribution analysis with the Nano-DMA, particle size by transmission electron microscopy, C/H analysis, g filter analysis, and thermogravimetric analysis using both non-oxidative and oxidative pyrolysis. The WSR can generate young soot particles that can be collected and examined to gain insight into inception. For the current conditions, soot does not form for ${\Phi}=1.9$, inception occurs at or before ${\Phi}=2.0$, and inception combined with soot surface growth and/or coagulation occurs for ${\Phi=2.1}$. The filter samples for ${\Phi}$=1.9 are composed of volatile compounds that evolve at relatively low temperatures when heated in the presence or absence of $O_2$. The samples collected from the WSR at ${\Phi}=2.0$ and ${\Phi}=2.1$ are precursor-like in morphology and size. They have higher C/H ratios and lower organic percentages than precursor particles, but they are clearly not fully carbonized soot. The WSR PAH distribution is similar to that in young soot from inverse flames.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.101-101
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• 2010

ZnO shows a direct band gap of 3.37eV, large exciton binding energy (~60 meV), high oxidation ability, high sensitivity to many gases, and low cost, and it has been used in various applications such as transparent electrodes, light emitting diodes (LEDs), gas sensors and photocatalysts. Among these applications ZnO as photocatalyst has considerably attracted attention over the past few years because of its high activities in removing organic contaminants generated from industrial activities. In this research, ZnO nanoparticles were synthesized by spray-pyrolysis method using the zinc acetate dihydrate as starting material at synthesis temperature of $900^{\circ}C$ with concentration varied from 0.01 to 1.0M. The physical and chemical properties of the synthesized ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increased precursor concentration, a primary, secondary particle sizes of ZnO nanoparticles increased by 0.8 to $1.5{\mu}m$ and 15 to 35nm, and their crystallinity was improved. Methyleneblue (MB) solution ($1{\mu}M$) as a test comtaminant was prepared for evaluating the photocatalytic activities of ZnO nanoparticles synthesized in different precursor concentration. The results show that the photocatalytic efficiency of ZnO nanoparticles was gradually enhanced by increased precursor concentration.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.2
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• pp.178-189
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• 1994

Fine $BaTiO_3$ powder was synthesized from the various starting solution with 0.05 M by ultrasonic spray pyrolysis method. The conditions of synthesis were fixed on flow rate was 0.5 cm/sec, low temperature furnace was $300^{\circ}C$, and high temperatures furnace was $700^{\circ}C$. The formation procedure was investigated directly by SEM with the collected particle from the each reaction step. Also, the trace of particle in reaction tube was researched theoretically. Fine $BaTiO_3$ was synthesized only in the case of nitrate aqueous solution. The synthesized $BaTiO_3$ powder was porous and spherical which was consist of primary particle at the size of 19.1 nm. The formation procedure was as follows : the particle size decreased in drying step and then increased in initial thermal decomposition step. Finally, particle size was decreased to $0.42 {mu}m$. The trace of particle in reaction tube was also theoretically simulated and discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.759-765
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• 2012

This study investigates the effect of diesel combustion strategies on exhaust emissions and hydrocarbon species emissions for a 1.7 L common rail direct injection diesel engine at 1500 rpm and 3.9 bar BMEP. The first strategy is a method to adopt no EGR with a split injection composed of pilot and main injection (split injection). The second is to adopt a moderate EGR rate with main injection only (single-1). The third is to use a high level of EGR and main injection with rail pressure increase, $i.e.$ low-temperature diesel combustion (single-2). Split injection and single-1 showed a renowned phenomenon of a PM-NOx trade-off, whereas single-2 was observed of a PM-NOx trade-off to reduce PM and NOx simultaneously. HC speciation results show that the split injection produced the least amount of HC species, regardless of the carbon number bin, followed by single-1 and single-2. The ratios of methane, acetylene, and CO to THC increased as a combustion A/F ratio is richer due to reduced oxygen content in the vicinity of the combustion zone, thus enhancing pyrolysis.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.646-652
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• 2016

Biomass is regarded as one of the promising energy sources to deal with the depletion of fossil fuels and the global warming issue. Biocrude-oil can be produced through the fast pyrolysis of biomass feedstocks such as wood, crops, agricultural and forestry residues. It has significantly higher viscosity than that of conventional petroleum fuel and contains solid residues, which can lower the spray and atomization characteristics when applied to the burner. In addition, biocrude-oil consists of hundreds of chemical species derived from cellulose, hemicellulose and lignin, and evaporation characteristics of the biocrude-oil droplet are distinct from the conventional fuels. In the present study, a numerical study was performed to investigate the evaporation characteristics of biocrude-oil droplet using a simplified composition of the model biocrude-oil which consists of acetic acid, levoglucosan, phenol, and water. The evaporation characteristics of droplets were compared at various surrounding air temperatures, initial droplet diameters, and ethanol mixing ratios. The evaporation time becomes shorter with increasing air temperature, and it is much sensitive to the air temperature particularly in low temperature ranges. It was also found that the biocrude-oil droplet evaporates faster in cases of the smaller initial droplet diameter and larger ethanol mixing ratio.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.75-82
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• 2016

The technology of fast pyrolysis is regarded as a promising route to convert lignocellulose biomass into bio-oil which can be upgraded to transportable fuels and high quality chemical products. Despite these promises, commercialization of bio-oil for fuels and chemicals production is limited due to its notoriously undesirable characteristics, such as high and changing viscosity, high water and oxygen contents, low heating value and high acidity. Therefore, in this study quality improvement of bio-oil through vaccum distillation had been targeted. A 600 g of cork oak(Quercus variabilis) which grounded 0.8~1.4 mm was processed into bio-oil via fast pyrolysis for 1.64 seconds at $465^{\circ}C$ and temperature of vaccum distillation(100hPa) was designed to control, $40^{\circ}C$, 50, 60, 70, and 80 for 30min. Bio-oil, biochar, and gas of pyrolytic product were produced to 62.6, 18.0 and 19.3 wt%, respectively. The water content, viscosity, HHV(Higher Heating Value) and pH of bio-oil were measured to 0.9~26.1 wt%, 4.2~11.0 cSt 3,893~5,230 kcal/kg and 2.6~3.0, respectively. Despite these quality improvement, production was still limited due to its notoriously undesirable characteristics, therefore continous quality improvement will be needed in order to use practical fuel of bio-oil.