• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.283-291
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• 2017

Rice that the half of population in the world eats as a staple food is mostly produced and consumed in Asia. However, its consumption is nowadays decreasing mainly due to diet diversity. Accordingly, some attempts are in demand to enhance the utilization of rice. In this study, profiling of volatile and non-volatile flavor components in rice pastes obtained by ${\alpha}$-amylase was performed and compared according to nine different rice cultivars domestically cultivated in Korea using gas chromatography-mass spectrometry combined by solid phase microextraction and gas chromatography-time of flight-mass spectrometry after a derivatization, respectively. In total, 46 volatile compounds identified included 6 alcohols, 6 aldehydes, 4 esters, 4 furan derivatives, 4 ketones, 1 acid, 1 sulfur-containing compound, 7 hydrocarbons, 5 aromatics and 8 terpenes. The non-volatile flavor components found were composed of 12 amino acids, 6 sugars and 4 sugar alcohols. In principal component analysis, rice paste samples could be discriminated according to cultivars on the score plots of volatile and non-volatile flavor compounds. In particular, some volatile compounds such as pentanal and 4,7-dimethylundecane could contribute to distinguish Senong 17 white and Senong 17 brown, whereas ethanol, 6-methylhep-5-en-2-one, and tridecane could be highly related to the discrimination of Iipum from other cultivars. Among non-volatile compounds, some amino acids such as glycine, serine and ${\gamma}$-aminobutyric acid and some sugars such as sucrose and fructose were mainly responsible for the discrimination of Danmi from the other cultivars. On the other hand, galactose, arabitol and mannose were more closely related to Senong 17 white than Senong 17 brown.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.388-393
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• 2013

It has been well documented that Bacillus vallismortis strain EXTN-1, a beneficial rhizosphere bacterium, could enhance plant growth and induce systemic resistance to diverse pathogens in plants. However, the molecular mechanisms for how the EXTN-1 promote plant growth and induce resistances to diverse pathogens. Here, we show that 3-Hydroxy-2-butanone, a volatile organic compound (VOCs) emitted from the EXTN1, is a key factor for the bacteria-mediated beneficial effects on plant growth and defense systems. We found that the presence of volatile signals of EXTN-1 resulted in growth promotion of tobacco seedlings. The identification and analysis of EXTN-1-secreted volatile signals by solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) indicated that a 3-hydroxy-2-butanone could provide not only the plant growth promotion, but also higher resistance against Pectobacterium carotovorum SCC1. These results suggest that a volatile compound released from EXTN-1 enhances the plant growth promotion and immunity of plants.

• Korean Journal of Food Science and Technology
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• v.51 no.6
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• pp.543-550
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• 2019

In this study, volatile compounds in 13 aged and 3 commercial rice-distilled soju samples were isolated by headspace solid phase microextraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 85 volatile components including 35 esters, 15 alcohols, 5 ketones, 3 aldehydes, 15 miscellaneous, and 14 unknowns were identified. Esters and alcohols were the largest groups among the quantified volatiles. Differences in volatile compounds among the distilled soju samples and possible sample groupings were examined by principal component analysis of the GC-MS datasets. The first and second principal components (PC1 and PC2, respectively) explained 51.94% of the total variation across the 16 samples. The samples aged in oak containers had higher concentrations of ketones, aldehydes, and miscellaneous compounds. In the positive direction of PC1, oak-aged samples were observed, while, pot-aged samples were observed on the far negative side. Furthermore, samples aged for longer periods, such as 18 months, were observed in the positive direction of PC2.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.77-77
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• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.406-406
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• 2016

To get high efficiency n-type crystalline silicon solar cells, passivation is one of the key factor. Tunnel oxide (SiO2) reduce surface recombination as a passivation layer and it does not constrict the majority carrier flow. In this work, the passivation quality enhanced by different chemical solution such as HNO3, H2SO4:H2O2 and DI-water to make thin tunnel oxide layer on n-type crystalline silicon wafer and changes of characteristics by subsequent annealing process and firing process after phosphorus doped amorphous silicon (a-Si:H) deposition. The tunneling of carrier through oxide layer is checked through I-V measurement when the voltage is from -1 V to 1 V and interface state density also be calculated about $1{\times}1012cm-2eV-1$ using MIS (Metal-Insulator-Semiconductor) structure . Tunnel oxide produced by 68 wt% HNO3 for 5 min on $100^{\circ}C$, H2SO4:H2O2 for 5 min on $100^{\circ}C$ and DI-water for 60 min on $95^{\circ}C$. The oxide layer is measured thickness about 1.4~2.2 nm by spectral ellipsometry (SE) and properties as passivation layer by QSSPC (Quasi-Steady-state Photo Conductance). Tunnel oxide layer is capped with phosphorus doped amorphous silicon on both sides and additional annealing process improve lifetime from $3.25{\mu}s$ to $397{\mu}s$ and implied Voc from 544 mV to 690 mV after P-doped a-Si deposition, respectively. It will be expected that amorphous silicon is changed to poly silicon phase. Furthermore, lifetime and implied Voc were recovered by forming gas annealing (FGA) after firing process from $192{\mu}s$ to $786{\mu}s$. It is shown that the tunnel oxide layer is thermally stable.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.12
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• pp.1615-1621
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• 2008

The characteristics of volatile flavor compounds of Fuji apples were compared by different extraction methods for information leading to a natural fragrance development. The volatile flavor components of Fuji apples were extracted using simultaneous steam distillation and extraction (SDE), solvent extraction (SE), and solid-phase microextraction (SPME) methods and then analyzed by gas chromatograph-mass spectrometer. A total of 66, 32 and 54 components were identified in SDE, SE and SPME extracts, respectively. (E,E)-$\alpha$-Farnesene, hexanol, butanol, 2-methyl butanol, hexyl hexanoate, hexyl 2-methyl butanoate, hexyl butanoate, and butyl hexanoate were the major flavor components in the extracts by different methods, but the composition of volatiles in the extracts were different. Alcohols and hydrocarbons were the major functional groups in SDE and SE extract whereas esters and hydrocarbons were the major functional groups in SPME extracts. SPME was the most suitable method for analysis of fresh volatiles from Fuji apples.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.347-356
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• 1992

Various kaolin samples with different alumina content were prepared from calcined admixture of kaolin and ammonium sulfate by varying the treatment time in sulfuric acid. Samples were nitridated under N2 or N2-H2 atmosphere with changing the amount of added carbon, the reaction time and temperature. As the alumina content lowered, the size of kaolin particles decreased and the specific surface area increased. XRD analysis indicated that ${\alpha}$-quartz remained by decomposition of halloysite and meta-halloysite. Experimental results of nitridation behavior are summerized as follows; 1) Nitridation under N2 atmosphere. With the increase of C/SiO2 ratio and with the decrease of Al2O3 content, disappearance of XRD pattern peaks of mullite, ${\alpha}$-quartz and ${\alpha}$-Al2O3 were accelerated at 1300$^{\circ}C$. SiC was the main phase in the reaction product of acid-treated kaolin samples nitridated at 1300$^{\circ}C$ for 10 hours regardless of C/SiO2 ratio. But the XRD peak intensities of ${\beta}$-Si3N4, ${\beta}$-sialon and SiC did not show much difference when untreated raw kaolin was fired at the same condition. When the ratio of C/SiO2 was 3.5, ${\beta}$-sialon and ${\beta}$-Si3N4 existed in the reaction product of about 22% alumina containing kaolin sample fired at 1350$^{\circ}C$ for 7 hours. Only ${\beta}$-sialon existed in the same sample fired at 1400$^{\circ}C$ for 10 hours. ${\beta}$-sialon was obtained from all of the acid-treated kaolin samples fired at 1400$^{\circ}C$ for 40 hours, but AlN and SiC remained in the untreated kaolin sample. Z value of the ${\beta}$-sialon obtained from the 22% alumina containing kaolin sample fired at 1400$^{\circ}C$ for 40 hours was about 1.3(XRD) and 1.5(EDS). 2) Nitridation under 80N2+2OH2 mixed gas atmosphere with the C/SiO2 ratio of 1 Mullite was not found, but ${\alpha}$-Si3N4, and ${\beta}$-sialon were present in the reaction product of about 22% alumina containing kaolin sample fired at 1300$^{\circ}C$ for 10 hours. When untreated kaolin sample was nitridated at the same condition, mullite remained. AlN and SiC were not found in the reaction product of about 22% alumina containing kaolin sample fired at 1350$^{\circ}C$ for 5 hours. On the other hand, AlN and SiC remained in the product of untreated kaolin fired at the same condition.

• Journal of the Korean earth science society
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• v.38 no.6
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• pp.405-420
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• 2017

We investigated the H I, He II and O III emission lines of the symbiotic star AG Peg, using the spectroscopic data secured at different phases in three periods at the Lick Observatory. We measured FWHM and the intensity of six O III Bowen lines and studied the efficiency of fluorescence mechanism. The mean FWHM of O III normal and Bowen lines observed during three time periods did not make much difference, while Bowen line intensities are about 4.0 times higher than the normal lines. Comparing the predicted and the observed ratios, we found that the observed intensities are higher than predicted intensities, except for O III ${\lambda}$ 3759.87. The O III ${\lambda}$ 3791.26 and 3754.67 intensity ratios observed only in 2001 are in good agreement with the predictions by Saraph and Seaton (1980). We obtained the Bowen efficiency parameter (R)=0.47 for 2002, but we could not find R for the other two periods of time. Because of this, based on the 2002 efficiency result, we calculated the intensity ratio of O III normal and Bowen lines relative to He II ${\lambda}$ 4685.68 and derive the efficiency variation with time period. The result showed that the efficiency is the highest in 1998 and the lowest in 2001. We conclude that the efficiencies with phase are caused by the electron temperature changes in the ionized gas. The efficiencies of AG Peg are likely to increase along with electron temperature. Our analysis results may be useful in understanding the physical conditions of the ionized shell in symbiotic star and the intensity ratio and efficiency variation.

• Journal of the Korean earth science society
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• v.38 no.3
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• pp.209-221
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• 2017

We investigate the star formation rate, stellar mass, and gas-phase metallicity of local starburst galaxies with different star formation time scales based on their optical spectra. The observation is made using the longslit spectrograph attached to the 4K CCD on the Bohyunsan Optical Astronomy Observatory 1.8m telescope, targeting 21 Wolf-Rayet galaxies as young starbursts and 13 UV excess galaxies as slightly older starbursts. A Baldwin-Phillips-Terlevich diagram analysis shows that 50% of the observed targets are pure star-forming galaxies while only 15% are classified as Active Galactic Nuclei. Fraction of galaxies that reside in composite region is higher in UV excess galaxies than in Wolf-Rayet galaxies, suggesting that the AGN development requires extra time after the onset of the star formation. Most of the observed starburst galaxies have stellar masses of $10^{9-11}M_{\odot}$ and stellar formation rates of $0.01-100M_{\odot}yr^{-1}$, and their star formation rates are consistent with that of the SDSS star forming main sequence galaxies of similar stellar mass. There is no significant difference between Wolf-Rayet galaxies and UV excess galaxies in terms of the stellar mass and star formation rate. We also see a mass-metallicity relation for local starbursts with slightly lower metallicity for a given stellar mass, which implies the existence of a strong feedback activity due to the star formation in these galaxies.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.115-123
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• 1998

Vinyl chloride monomer exists as gas phase at normal temperature and reacts with oxygen and strong oxidant in the air to form oxidized materials. Because of being easily synthesized, it is used as a main source at the synthetic reaction process of PVC synthesis factories. Ministry of Labor regulates its usage as a carcinogen and its exposure level as 1 ppm. But the amount of VCM production in PVC and VCM production process hasn't been exactly estimated. In addition, facilities of this factory are located in outdoor. Therefore, this study was designed to investigate effects of temperature on breakthrough of charcoal tube at a fixed concentration and temperature during VCM sampling based on NIOSH and OSHA methods which were used as methods of occupational environment measuring and analysis. During the sampling of VCM, methods of OSHA and NIOSH require flow rate of 0.05 lpm and sampling volume of $3{\ell}$, $5{\ell}$ respectively, at this time carbon molecular sieve tube and coconut shell charcoal tube are used to observe the breakthrough along with concentration and temperature. As a result, significant difference between average adsorbed amounts of OSHA methods but that of NIOSH methods cannot be found. NIOSH method is likely to be effected by high temperature and normal temperature in high concentration. Breakthrough is not found in the method of OSHA at different conditions of temperature and concentration. As the result of this study we could verify that breakthrough occurred in the process of sampling VCM with NIOSH methods. Therefor in summer time, breakthrough should be considered and research on the breakthrough volume should be done. It is considered the research about the specificity of the coconut shell charcoal and carbon molecular sieve sorbent should be done when sampling VCM in comming days.