• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.440-444
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• 2012

In this work, a semi-carbonized wood chip (SC-WC) was prepared by heat-treatment at low carbonization temperature. The pyrolysis characterization and heating value of the SC-WC at different heat-treatment temperature were evaluated. The pyrolysis characterization and heating value of the SC-WC were determined using thermal gravimetric analyzer (TGA) in $N_{2}$ atmosphere and calorimeter, respectively. From the TGA results, the thermal decomposition reaction of the SC-WC treated at by low temperature was similar to pure wood chip and the reaction was most actively occurred in the range of $200^{\circ}C$ to $400^{\circ}C$, whereas the initial thermal decomposition temperature of the SC-WC increased with the increasing heat-treatment temperature. In addition, the heating value of the SC-WC showed a similar trend as to the decamposition temperature behavior. This is probably attributed to increased carbon content of SC-WC by the localized carbonization of the wood chip which consisted of cellulose, hemi-cellulose, and lignin.

• Food Science of Animal Resources
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• v.28 no.2
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• pp.154-159
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• 2008

To investigate the rheological properties of protein mixed gels mediated by microbial transglutaminase (MTGase), pork myofibrillar protein (MFP), sodium caseinate (SC) and their mixture (MS), the various gels were incubated at different temperatures for various times. Extracted MFP, SC and their mixture (MS, 1:1) were incubated at different temperatures ($4^{\circ}C$ vs $37^{\circ}C$) for various times (0, 0.5, 2, 4 hr), and assessed for viscosity, gel strength and other characteristics using differential scanning calorimeter (DSC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). DSC measurements showed that incubation at $37^{\circ}C$ rather than $4^{\circ}C$ caused marked changes in thermal transition, and MS displayed similar thermal curves (three endothermic transitions) to MFP and SC alone. After incubation at $37^{\circ}C$ for 2 hrs, the viscosity (cP) of MS increased (p<0.05) due to induction by MTGase, whereas no differences were observed at $4^{\circ}C$. However, gel strength values were no different, regardless of incubation temperatures and times. Future research will address how longer incubation times affect the functionality of protein mixed gels mediated by MTGase.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.240-240
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• 2011

The first neutral beam injector (NBI-1) has been developed for the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. A first long pulse ion source (LPIS-1) has been installed on the NBI-1 for an auxiliary heating and current drive of KSTAR core plasmas. Performance of ion and neutral beam extractions in the LPIS-1 was investigated initially on the KSTAR NBI-1 system, prior to the neutral beam injection into the main plasmas. The ion source consists of a JAEA magnetic bucket plasma generator with multi-pole cusp fields and a set of KAERI prototype-III tetrode accelerators with circular apertures. The inner volume of plasma generator and accelerator column in the LPIS-1 is approximately 123 liters. Final design requirements for the ion source were a 120 kV/ 65 A deuterium beam and a 300 s pulse length. The extraction of ion beams was initiated by the formation of arc plasmas in the LPIS-1, called as an arc-beam extraction method. A stable ion beam extraction of LPIS-1 has been achieved up to an 100 kV/42 A for a 4 s pulse length and an 80 kV/25 A for a 14 s pulse length. Optimum beam perveance of 1.21 microperv has been found at an accelerating voltage of 80 kV. Neutralization efficiency has been measured by using a water flow calorimetry (WFC) method of calorimeter and an operation of bending magnet. The full-energy species of ion beams have been detected by using the diagnostic method of optical multichannel analyzer (OMA). An arc efficiency of the LPIS was 0.6~1.1 A/kW depending on the operating conditions of arc discharge.

• Membrane Journal
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• v.25 no.3
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• pp.223-230
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• 2015

We synthesized novel polyimides with high gas permeability and selectivity for application of gas separation membrane. 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) and two kinds of amines with high permeability and solubility were used to prepare the novel polymide. 2,4,6-Trimethyl-1,3-phenylenediamine (DAM) was used to improve gas permeability and 4,4-Methylenedianiline was used to improve the gas selectivity respectively. The polyimide copolymers were synthesized by commercial chemical imidization method using Triethylamine and Acetic anhydride and their average molecular weights were over 100,000 g/mol. The glass temperature (Tg) and the thermal degradation temperature were characterized using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The synthesized copolymers showed high Tg over $300^{\circ}C$ and high thermal degradation temperature over $500^{\circ}C$. The gas permeation properties were measured by time-lag equipment. Although general polyimides showed very low gas permeability, synthesized polyimide copolymer showed high $O_2$ permeability of 10.1 barrer with high $O_2/N_2$ selectivity around 5.3. From this result, we confirm that these membranes have possibility to apply to gas separation membrane.

• Membrane Journal
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• v.24 no.4
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• pp.325-331
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• 2014

We synthesized novel polyimides with high gas permeability and selectivity for application of on board inert gas generation system (OBIGGS). 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) and two kinds of amines with high permeability and solubility were used to prepare the novel polymide. 2,3,5,6-Tetramethyl-1,4-phenylenediamine (TMPD) was used to improve gas permeability and various kinds of diamines were used to improve the gas selectivity respectively. The polyimide copolymers were synthesized by commercial chemical imidization method and their average molecular weights were over 100,000g/mol. The glass temperature ($T_g$) and the thermal degradation temperature were characterized using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The synthesized copolymers showed high $T_g$ over $300^{\circ}C$ and high thermal degradation temperature over $500^{\circ}C$. The gas permeation properties were measured by time-lag equipment. Although general polyimides showed very low gas permeability, synthesized polyimide copolymer showed high $O_2$ permeability of 36.21 barrer with high $O_2/N_2$ selectivity around 4.1. From this result, we confirm that these membranes have possibility to apply to OBIGGS.

• Journal of Energy Engineering
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• v.16 no.1 s.49
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• pp.7-14
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• 2007

An experimental study is performed to investigate the effect of air-side heat transfer and friction on characteristics of finned tube heat exchanger under dry surface and wet surface conditions (RH 50%, 70%). Air enthalpy calorimeter is used to obtain the performance evaluation and analysis of a fined tube heat exchanger. Four finned tube heat exchangers with slit fin or plain fin are tested. The number of tube rows are 2 and 3, and the tube diameter is 7 mm. Air-side heat transfer and friction are presented in terms of j factor and friction factor. At dry surface condition, j factor decreases with increasing Re and j factor of 3 row is lower than that of 2 row. Also, the friction factor of a slit fin is larger than that of a plain fin. At wet surface condition, the heat transfer effect is more significant in the case of the slit fin than the plain fin and 2 row than 3 row. The j factor and friction factor are affected by humidity, tube row and fin configuration.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.77-83
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• 2007

It is essential that second order nonlinear optical materials have low optical propagation losses in the wavelengths of second harmonic generation for practical applications in waveguides. Three dipolar chromophores substituted with nitro, cyano, and alkyl sulfone as an electron withdrawing group were prepared. The UV-Vis absorption spectra of the cyano and alkylsulfone chromophores showed a blue-shift compared to the nitro chromophore. The introduction of oxadiazole segment in the chromophore structure led to similar spectral shift. The blue-shift can produce low optical loses at second harmonics. The chromophores were successfully attached to a polyimide, yielding side chain polymers. The nonlinear optical property of the prepared optical polymers was determined by measuring electro-optic coefficient at 1.55 mm. The polymers exhibited high glass transition temperature of over $185^{\circ}C$ and thermal stability to $300^{\circ}C$ through differential scanning calorimeter analysis and thermal gravimetric analysis.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.180-188
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• 2014

This study focused on assessing the solubility and structural characteristics of two types of coenzyme $Q_{10}$ ($CoQ_{10}$) complexes: the $CoQ_{10}$-starch and the $CoQ_{10}$-cyclodextrin complexes. The solubility of $CoQ_{10}$-starch complex increased significantly as the temperature was increased. However, the solubility of $CoQ_{10}$-cyclodextrin complex reached a peak at $37^{\circ}C$, and strong aggregation occurred at $50^{\circ}C$. When the temperature was raised to $80^{\circ}C$, the $CoQ_{10}$-cyclodextrin complex dissociated owing to the weakening of bonds, resulting in $CoQ_{10}$ emerging at the surface of water. Therefore, $CoQ_{10}$-cyclodextrin complexes have lower solubility, due to their reduced heat-stability, than do the $CoQ_{10}$-starch complexes. Structural differences between the two $CoQ_{10}$ complexes were confirmed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD), and differential scanning calorimeter (DSC). The $CoQ_{10}$-cyclodextrin complex included an isoprenoid chain of $CoQ_{10}$, while the $CoQ_{10}$-starch complex included both the benzoquinone ring and the isoprenoid chain of $CoQ_{10}$. These results suggest that $CoQ_{10}$-starch complexes possess higher heat-stability and solubility than do the $CoQ_{10}$-cyclodextrin complexes.

• Journal of the Society of Disaster Information
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• v.10 no.1
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• pp.71-83
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• 2014

This study carried out an experiment in order to compare thermal characteristics after collecting dust generated in the process of disposing of waste tire, plywood flour in the process of manufacturing plywood, salicylic acid dust in the process of manufacturing functional soap, and dust in the process of manufacturing wheat powder, which has potential fire and explosion hazard. According to the results of experiment, the analysis showed that all samples subject to the experiment were in the condition where heat flux decreased and temperature decreased as the quantity of added talc was increased. This shows that decomposition rate decreased, and hazard decreased. However, in all of samples subject to the experiment, as heating rate increased, endothermic onset temperature moved to the low-temperature part, and the amount of absorbed heat was largely increased. This showed that the decomposition hazard of sample increased as heating rate increased, according to the analysis. Besides, TGA experiment results showed that thermal stability was secured because total weight loss decreased as the amount of talc was increased for all samples subject to the experiment regarding the ratio of weight loss. It is expected that the continuous research and supplementation of dust explosion mechanism in the future will contribute to the establishment of measures for the effective dust explosion prevention.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.476-482
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• 2006

An experimental study has been performed to investigate the characteristics of air-side heat transfer and friction of a fined tube heat exchanger under heating conditions. Air enthalpy calorimeter was used to obtain the performance evaluation and analysis of the fined tube heat exchanger. Eight finned tube heat exchangers with slit fin, louver fin, and plain fin were used. The air-side heat transfer coefficient was calculated by the log-mean-temperature-difference. Air-side heat transfer and friction were presented in terms of j factor and friction factor on Reynolds number. From the experimental result, it was found that the variations of air-side heat transfer and friction of fined tube heat exchanger with the change of the fin configuration, row number, fin pitch, and tube circuit were obtained. j factor and friction factor decreased with Reynolds number increased. The tube circuit affected the air-side heat transfer and friction. In the case of slit and louver fin, j factor of 1st row was higher than that of 2nd row. But, with increasing Re, j factor was reversed. The characteristics of j factor and friction factor of 2nd row heat exchanger were different according to the kind of fins.