• Journal of the Korean Chemical Society
• /
• v.38 no.9
• /
• pp.640-652
• /
• 1994

This work is undertaken to determine alcohol homologues so-called fusel oil that may be present in the Korean folk sojues (distilled liquor) made from grains and to describe sample preparation and analytical method by GC-FID-MS. Solid phase extraction method for sample preparation by using porous styrene divinyl benzene polymer (Porapak Q) was compared with steam distillation and solvent extraction method. Retention behaviors of homologous series of alcohols were also studied. Log values of retention time, molecular weight, boiling point, and capacity factor of alcohols showed linear correlations to the carbon number of an alcohol, to the oven temperature, and to the dielectric constant. Components such as methyl alcohol, n-propyl alcohol, isobutyl alcohol, isopentyl alcohol, and phenethyl alcohol have been identified. The more amount of isopentyl alcohol than other alcohols are contained in the Korean folk sojues, while that of n-propyl alcohol are contained in Chinese kaoliangchiew. Degree of similarity or dissimilarity and classification of the individual samples were discussed using multivariate statistical analysis(principal components analysis) based on GC data.

• Korean Journal of Materials Research
• /
• v.14 no.1
• /
• pp.28-34
• /
• 2004

IN 738LC, the major material for gas-turbine for power generation, was heat treated at $750^{\circ}C$, $850^{\circ}C$, $950^{\circ}C$ for 1000, 2000, and 4000 hrs and the microstructural evolution and mechanical properties were examined using optical microscope, XRD, SEM/EDS. The results showed ${\gamma}$', the main strengthening elements in this alloy, was about 300 nm in size and was about 56% by area fraction in as-cast samples. The area fraction of ${\gamma}$' peaked at 2000 hours at $750^{\circ}C$. The average diameter of the ${\gamma}$' which was about 300 nm at ascast specimen increased to about 1 $\mu\textrm{m}$ after heat treatment at $950^{\circ}C$ for 4000 hrs. Carbides were formed at dendrite, cell or grain boundaries which was ascribed to the segregation caused by solute redistribution during solidification. It was found that MC type carbides formed at low temperature, whereas carbides of $M_{23}$ /$C_{ 6}$/ type formed at higher temperature or at longer degradation. The hardness and impact energy decreased as the heat treatment temperature or time of retention increased, which was inaccrodance with the area fraction of ${\gamma}$'.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.15 no.1
• /
• pp.143-148
• /
• 2007

The objective of this study was to investigate the proper conditions of calcination and calcium extraction from powdered oyster shell. The physical characteristics such as particle size distribution, surface morphology, and thermal gravity were examined. The following result were obtained. As the powdered oyster shell was ignited in high temperature of $650^{\circ}C$ to $950^{\circ}C$, the calcination reactions was effectively progressed. The amount of weight loss during calcination would be matched with the generation of carbon dioxide gas. In the calcination of powdered oyster shell, the amount of weight loss increased according to the increased of calcination temperature and the decrease of mean particle size. It was founded that the proper temperature and retention time of calcination was $850^{\circ}C$ and 40 minute. In the extraction of calcium into liquid form using acid addition, the calcination oyster shell was more effective than the non-calcinated shell. The liquid calcium extraction technique using the calcinated oyster shell needed more researches considering cost evaluation.

• Journal of Korean Society on Water Environment
• /
• v.16 no.4
• /
• pp.541-554
• /
• 2000

Experimental study of anaerobic digestion process combined with and without the submerged separation membrane was investigated by using laboratory-scale reactor at the hydraulic retention time of 0.5 day and 1.0 day. The removal efficiencies of carbohydrate at the digester without and with membrane were 84.4 to 86.8 % and 99.6 to 99.7 %, respectively, and the methane gas recovery efficiencies were 0.4 to 1.2 % and 12.3 to 28.7 %. According to the measurement by the most probable numbers method. the numbers of various groups of bacteria in the digesters with membrane were enumerated in the following ranges ; acidogens : $1.7{\times}10^9$ to $5.0{\times}10^9MPN/m{\ell}$, homoacetogens : $5.0{\times}10^7$ to $2.4{\times}10^8MPN/m{\ell}$, $H_2$-utilizing methanogens : $1.3{\times}10^7$ to $9.2{\times}10^8MPN/m{\ell}$, and acetate-utilizing methanogens : $2.3{\times}10^6$ to $2.0{\times}10^8MPN/m{\ell}$. The number of methanogens at the digester with membrane increased by approximately $10^2$ to $10^4$ times in comparison with that of the digester without membrane.

• Journal of the Korean Chemical Society
• /
• v.41 no.9
• /
• pp.471-482
• /
• 1997

GC/MS was used to find an optimum experimental condition for the screening of organic acids in urine. Urinary organic acids were isolated through the liquid-liquid extraction method (LLE) to examine the influence of pH and the effect of including the back extraction and oximation processes respectively on the extraction. When pH was adjusted to 0.5 during the extraction without oximation process, relatively higher recovery rate and the smallest relative standard deviations (0.3-12.4%) were obtained. By removing the interference, the addition of back extraction made possible surer identification of organic acids with retention time of 15-16 minutes. Under this condition, we obtained the content distribution of urinary organic acids in healthy Korean children (n=16) by establishing the calibration curves for 51 standard organic acids.

• Explosives and Blasting
• /
• v.28 no.1
• /
• pp.19-26
• /
• 2010

The paper presents a case study of a limestone quarry of the Philippines, where major problems in terms of improper fragmentation, poor wall control, and poor heave of the muck pile were witnessed. The paper highlights the significant role of switching over from diagonal firing pattern to V-type firing pattern, and also of making suitable adjustments in the stemming column length for improved confinement and gas retention. The study revealed that by making aforesaid design modifications in the blast round, marked improvement in blasting results was registered. Looking at the results, it was further contemplated to expand the mesh area in the subsequent blast rounds. The mesh area was incremented from the existing $8.96m^2$ to $12m^2$. The results were meticulously registered in the field, and clearly depicted definite improvements in the blast results in terms of increased P.F., reduced boulder count, reduced FEL cycle time, reduced dozing hours and improved heave.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.3
• /
• pp.331-339
• /
• 2007

The purpose of this study was to investigate the biodegradability and performance of organic removal and methane production rate when treating piggery wastewater using a pilot scale two-phase anaerobic system operated up to a volumetric rate of $10m^3/day$. The pilot scale two-phase anaerobic process is consisted of a continuous-flow stirred-tank reactor (CFSTR) for the acidification phase and an Upflow Anaerobic Sludge Blanket reactor (UASB) for the methanogenesis. The acidogenic reactor played key roles in reducing the periodically applied shock-loading and in the acidification of the influent organics. The acidogenic CFSTR was operated at organic loading rates (OLR) between 1.8 and $14.4kgCOD/m^3{\cdot}day$, and the UASB reactor was operated between 0.5 and $5.6kgCOD/m^3{\cdot}day$. A stable maximum biogas production rate was $81m^3/day$ and the methane conversion rate of the organic matter varied from 0.30 to $0.42L\;CH_4/g\;COD_{removed}$(0.40) at hydraulic retention time (HRT) above 3.5days. The methane contents ranged from 73 to 82% during the experimental period. It is known that most of the removed organic matter was converted to methane gas, and the produced biogas might be high quality for its subsequent use.

• The Korean Journal of Mycology
• /
• v.19 no.4
• /
• pp.292-298
• /
• 1991

Volatile aroma concentrates of Pleurotus sajor-caju which stored at $20^{\circ}C$ incubator and cold room were obtained by simultaneous distillation-extraction method. The volatile components were identified by combined capillary gas chromatography-mass spectrometry and comparison of retention data on GC of those authentic compounds. Storage at room temperature resulted in significant decreased in their total aroma contents, whereas little changes at cold storage foured, even though appreciable changes were observed in GC pattern between the control and stored samples. Of 38 components identified, ${\delta}-decalactone$ increased while rest of the volatiles decreased rapidly during storage at room temperature, but at cold storage 2-methyl butanal, 1-octen-3-ol, cis,cis-1,5-octadien-3-ol and pentadecanoic acid decreased while 3-octanone, 1-octen-3-one, 3-octanol and 5-undecanol increased with the storage time. The weight losses and organoleptic properties changed extremely by the storage under room temperature, on the other hand, slight changes were found in cold storage.

• Applied Biological Chemistry
• /
• v.40 no.2
• /
• pp.144-147
• /
• 1997

Different isolation methods for the volatile components of Anise(Pimpinella anisum L.) are compared in terms of the difference of components obtained with each analytical procedure. These methods include headspace(purge & trap) sampling procedure, simultaneous distillation extraction(SDE), steam distillation and solvent extraction. Total 43 components were identified by? comparing gas chromatography retention time and mass spectral data. Different isolation techniques result in compositionally different isolates. The headspace(purge & trap) sampling procedure was found to be the best method of choice for a qualitative analysis of the volatile components.

• YAKHAK HOEJI
• /
• v.42 no.6
• /
• pp.576-582
• /
• 1998

Fenfluramine, an anorectic agent, is widely abused as a diet pill in Korea because it is freely marketed in China without any regulation. The optical isomers of fenfluramine hav e different phamacological actions: d-form is used as an anorectic agent, while l-form as a neuroleptic agent. To investigate the metabolism when racemic fenfluramine was administered orally, the urinary excretion of fenfluramine was studied in rats. The enantiomeric separation of fenfluramine was performed on achiral column by gas chromatography using (S)-N-(trifluoroacetyl)-l-prolyl chloride (TFP) as a derivatizing agent. After administration of 15mg/kg of racemic fenfluramine to rats, d-, l-fenfluramine and its metabolites d- and l norfenfluramine in urine were determined by chromatographic separation of TFP derivatives on DB-1 at retention time of 11.2, 11.8, 8.4 and 8.6 min respectively. Urinary recoveries of d and l-fenfluramine in rat were 0.42-5.9O% and 0.18-1.20% respectively in urine specimens collected during first 24hr. The comparison in the levels of isomers showed that d- fenfluramine were higher than l-form, while d-norfenfluramine were lower than l-form. The ratios between parent compound and metabolite revealed that d-norfenfluramine to d-fenfluramine ranged from 1.0 to 4.4, while the ratio of l-norfenfluramine to l-fenfluramine was 8.2-21.1 indicating that l-fenfluramine is metabolized faster than the d-isomer.