• The Journal of Engineering Geology
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• v.21 no.2
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• pp.163-178
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• 2011

A test borehole was drilled in the Cheongwon area to investigate the relationship between geochemical environment and the natural occurrence of radioactive materials (uranium and Rn-222) in borehole groundwater. The borehole encountered mainly biotite schist and biotite granite, with minor porphyritic granite and basic dykes. Six groundwater samples were collected at different depths in the borehole using the double-packed system. The groundwater pH ranges from 5.66 to 8.34, and the chemical type of the groundwater is Ca-$HCO_3$. The contents of uranium and Rn-222 in the groundwater are 0.03-683 ppb and 1,290-7,600 pCi/L, respectively. The contents of uranium and thorium in the rocks within the borehole are 0.51-23.4 ppm and 0.89-62.6 ppm, respectively. Microscope observations of the rock core and analyses by electron probe microanalyzer (EPMA) show that most of the radioactive elements occur in the biotite schist, within accessory minerals such as monazite and limenite in biotite, and in feldspar and quartz. The high uranium content of groundwater at depths of -50 to -70 m is due to groundwater chemistry (weakly alkaline pH, an oxidizing environment, and high concentrations of bicarbonate). The origin of Rn-222 could be determined by analyzing noble gas isotopes (e.g., $^3He/^4He$ and $^4He/^{20}Ne$).

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.452-458
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• 2010

This study aimed at improving the packaging technology of Yukwa to improve the quality and extend the shelflife using secondary packaging. After packaging the Yukwa using an OPP film, P2, P3, and P4 packaging materials were applied secondarily. Various films including (1) P1: OPP (oriented polypropylene), (2) P2: P1+OPP/LLDPE (linear low density polyethylene), (3) P3: P1+PET (polyethylene terephthalate)/NY (nylon)/CPP (cast polypropylene) and (4) P4: P1+PET/AL (aluminum)/NY/CPP (P4) were used for packaging Yukwa. The experiment was conducted at $25^{\circ}C$ for 12 weeks. P1 showed the highest acid value score (1.26 mg KOH/g), and P3 had the highest peroxide value score (32.91 meq/kg) among all packaging groups. Nevertheless, these values did not exceed the guideline values of 2.0 g KOH/g and 40 meq/kg specified in the Korean food code. The overall color difference showed a tendency for decreasing Hunter 'L' values and increasing 'a' and 'b' values; however, no noticeable difference in the outer appearance was observed in any of the packaging treatments except in the P1 for greater than 10 weeks of storage. Some texture defects were observed in the Yukwa when the moisture contents dropped below 5%. The P4 packaging treatment had the lowest moisture permeability and showed the least rheological deterioration change, followed by P3 and P2. In conclusion, the use of a secondary packaging with less gas and moisture permeability was more effective for maintaining the quality and extending the shelf-life of Yukwa than other types of packaging material.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.383-389
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• 2010

The aim of this study was to determine the methylmercury (MeHg) levels in abyssal fish species. The MeHg in the fishes was extracted with hydrochloric acid and toluene and then purified using an L-cysteine solution. The extract was analyzed with a gas chromatography-electron capture detector (GC-${\mu}ECD$) with a thermon Hg-capillary column. The detection limit and the recovery of the method were 0.002 and 84.2-98.5% (mean, 93.4%), respectively. The MeHg content in 492 abyssal fishes ranged from 0.037 to 2.009 mg/kg. The levels of MeHg [range, mg/kg (mean)] were significantly dependent on fish species and presented as the following; 0.157-2.009 (0.546) in Scalloped hammerhead shark, 0.211-0.878 (0.501) in Blue shark, 0.121-0.993 (0.482) in Spiny dogfish, 0.243-0.658 (0.397) in Salmon shark, 0.074-1.958 (0.353) in Blacktip shark, 0.038-0.807 (0.302) in Southern hake, 0.099-0.511 (0.300) in Scorpion fish, and 0.037-0.133 (0.067) in Ling. The monitoring results showed that the estimated weekly intake of MeHg from sharks, Southern hake, and Ling were lower than the provisional tolerable weekly intake recommended by the Joint FAO/WHO expert committee on food additives.

• Journal of Life Science
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• v.18 no.12
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• pp.1625-1630
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• 2008

A microorganism capable of producing high level of poly-3-hydoxybutyrate (PHB) from xylose was isolated from soil. The isolated strain J-65 was identified as Bacillus megaterium based on the morphological, biochemical and molecular biological characteristics. The optimum temperature and pH for the growth of B. megaterium J-65 were $37^{\circ}C$ and 8.0, respectively. The optimum medium composition for the cell growth was 2% xylose, 0.25% $(NH_4)_2SO_4$, 0.3% $Na_2HPO_4{\cdot}12H_2O$, and 0.1% $KH_2PO_4$. The optimum condition for PHB accumulation was same to the optimum condition for cell growth. Copolymer of ${\beta}$-hydroxybutyric and ${\beta}$-hydroxyvaleric acid was produced when propionic acid was added to shake flasks containing 20 g/l of xylose. Fermenter culture was carried out to produce the high concentration of PHB. In batch culture, cell mass was 9.82 g/l and PHB content was 35% of dry cell weight. PHB produced by B. megaterium J-65 was identified as homopolymer of 3-hydoxybutyric acid by GC and NMR.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.472-481
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• 2000

This experiment used the enclosed bench-scale reactors was conducted to find out optimal aeration rate for reducing the emission of odors and producing the good-quality compost with the mixture of dairy manure and rice straw. The reactors with gas sampler were aerated at four different rates of 0.09, 0.18, 0.90 and $1.79l\;min^{-1}kg^{-1}$dry solids for 574 hours. The oxygen content within composting pile instantly decreased after aeration. Oxygen limitation(below 15%) in the treatments of $0.90l\;min^{-1}kg^{-1}$ and less was exponentially negative relationship with aeration rates and in the range of 35 to 300 hours after aeration. However, the treatment of $1.79l\;min^{-1}kg^{-1}$ didn't show the oxygen limitation. The oxygen consumption rate and the cumulative amount of oxygen consumed by different aeration rates was ranged in $0.80{\sim}1.57O_2g\;h^{-1}\;kg^{-1}VS^{-1}$, $460{\sim}900O_2g\;kg^{-1}VS^{-1}$, respectively, and they were high in the order of 0.90, 1.79, 0.18, $0.09l\;min^{-1}kg^{-1}$. The maximum oxygen consumption rate was estimated in the range of $1.2{\sim}1.3lmin^{-1}kg^{-1}$. The emission concentrations of sulfur compounds such as hydrogen sulfide, sulfur dioxide and methylmercaptan were remarkably high in the initial composting time. Then they were rapidly decreased with the passing of composting time and clearly with increasing aeration rates. Their average concentrations were in the range of 0.03~2.18, 0~0.50, $0.07{\sim}3.38mg\;kg^{-1}$, respectively and high in the order of methylmercaptan, hydrogen sulfide, and sulfur dioxide. Concentrations of sulfur compounds emitted from composting showed exponentially negative relationship at 1% statistically with the oxygen concentration. It was estimated that hydrogen sulfide and methylmercaptan suddenly increased in the level of 5% oxygen concentration and below, that they were little emitted in 15% and over but sulfur dioxide was emitted in the level of 20% oxygen.

• Journal of Animal Science and Technology
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• v.48 no.2
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• pp.293-306
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• 2006

We characterized physicochemical properties and examined the organoleptic and textural evaluations of Feta cheese made from goat's milk. Nutritional compositions of goat Feta cheese were fat 23.50%, protein 11.03% with moisture content of 59.54%. Cell numbers of lactic starter cultures in Feta cheese maintained from log 8.46 CFU/g and pH 5.76 during storage at 4℃ for 14 day's aging. The color of Feta cheese was whitish (L. 93.19) at after finishing brine salting, but became a little yellowish(b. 3.52) (a. -0.71). For texture profile analysis of goat Feta cheese, hardness, fracturability springness, and cohesiveness seemed to be week, but adhesiveness gumminess, chewiness, and resilience were enhanced as aging times extended to 14days, resulted in the overall textural properties was to be superior to control cheese(commercial Mozzarella cheese). Organoleptic evaluations were examined based on the intensities and the preferences for flavour, tastes, texture and mouth feeling. saltiness, bitterness and acidity were stronger in the intensities than control cheese, but the preferences were enhanced by aging to be better than control cheese at 14 days and later on, however, the texture changed to be weaker in hardness and unpleasant in mouthfeel. The fatty acid compositions of Feta cheese analysed by Gas chromatography were saturated fatty acid 42.06%, monoenoic acids 29.67%, di-enoic acids 24.24%, tri-enoic acids 1.21%.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.157-163
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• 2012

BACKGROUND: For the safety of imported agricultural products, the study was conducted to develop the analytical method of unregistered pesticides in domestic. The analytical method of 6 pesticides, chlorthal-dimethyl, clomeprop, diflufenican, hexachlorobenzene, picolinafen, and propyzamide, for a fast multi-residue analysis were established for two different type crops, orange and brown rice by GC-ECD and confirmed by mass spectrometry. METHODS AND RESULTS: The analytical method was evaluated to limit of quantification, linearity and recoveries. The crop samples were extracted with acetonitrile and performed cleanup by liquid-liquid partition and Florisil SPE to remove co-extracted matrix. The extracted samples were analyzed by GC-ECD with good sensitivity and selectivity of the method. The limits of quantification (LOQ) range of the method with S/N ratio of 10 was 0.02~0.05 mg/kg for orange and brown rice. The linearity for targeted pesticides were $R^2$ >0.999 at the levels ranged from 0.05 to 10.0 mg/kg. The average recoveries ranged from 74.4% to 110.3% with the percentage of coefficient variation in the range 0.2~8.8% at two different spiking levels (0.02 mg/kg and 0.2 mg/kg, 0.05 mg/kg and 0.5 mg/kg) in brown rice. And the average recoveries ranged from 77.8% to 118.4% with the percentage of coefficient variation in the range 0.2~6.6% at two different spiking levels (0.02 mg/kg and 0.2 mg/kg, 0.05 mg/kg and 0.5 mg/kg) in orange. Final determination was by gas chromatography/mass spectrometry/selected ion monitoring (GC/MS/SIM) to identify the targeted pesticides. CONCLUSION: As a result, this developed analytical method can be used as an official method for imported agricultural products.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.381-388
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• 2017

In this study, we investigated the levels of natural preservatives of benzoic acid, sorbic acid, and propionic acid in spices. The quantitative analysis was performed using high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) for benzoic acid and sorbic acid and gas chromatography-mass spectrometry (GC-MS) for propionic acid. The sample was extracted with ethanol using sonication, then centrifuged and evaporated to dryness and redissolved to 1 mL with ethanol to use for the instrumental analysis. The analytical method was validated based on linearity, recovery, limit of detection (LOD), and limit of quantification (LOQ). This method was suitable to determine low amounts of naturally occurring preservatives (benzoic acid, sorbic acid, and propionic acid) in various spices. Benzoic acid, sorbic acid, and propionic acid were found in 165 samples, 88 samples, and 398 samples, respectively from the total of 493 samples. The concentration of benzoic acid, sorbic acid, and propionic acid were ranged at ND-391.99 mg/L, ND-57.70 mg/L, and ND-188.21 mg/L in spices, respectively. The highest mean levels of benzoic acid, sorbic acid, and propionic acid were found in cinnamon (167.15 mg/L), basil leaves (22.79 mg/L), and white pepper (51.48 mg/L), respectively. The results in this study provide ranges of concentration regarding naturally occurring benzoic acid, sorbic acid, and propionic acid in spices. Moreover, the results may use to the case of consumer complaint or trade friction due to the inspection services of standard criteria for the preservatives of spices.

• Economic and Environmental Geology
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• v.25 no.3
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• pp.259-273
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• 1992

The Seongsan mine is one of the largest dickite deposits in the southwestern part of the Korean Peninsula. The main constithent minerals of the ore are dickite and quartz with accessory alunite, kaolinite and sericite. The geology around the Seongsan mine consists mainly of the late Cretaceous felsic volcanic rocks. In the studied area, these rocks make a synclinal structure with an axis of E-W direction plunging to the east. Most of the felsic volcanic rocks have undergone extensive hydrothermal alteration. The hydrothermally altered rocks can be classified into the following zones: Dickite, Dickite-Quartz, Quartz, Sericite, Albite and Chlorite zones, from the center to the margin of the alteration mass. Such zonal arrangement of altered rocks suggests that the country rocks, most of which are upper part of the rhyolite and welded tuff, were altered by strongly acid hydrothermal solutions. It is reasonable to consider that initial gas and solution containing $H_2S$ and other compounds were oxidized near the surface, and formed hydrothermal sulfuric acid solutions. The mineralogical and chemical changes of the altered rocks were investigated using various methods, and chemical composition of fifty-six samples of the altered rocks were obtained by wet chemical analysis and X.R.F. methods. On the basis of these analyses, it was found that some components such as $SiO_2$, $Al_2O_3$, $Fe_2O_3$, CaO, MgO, $K_2O$, $Na_2O$ and $TiO_2$ were mobilized considerably from the original rocks. The formation temperature of the deposits was estimated as higher than $200^{\circ}C$ from fluid inclusion study of samples taken from the Quartz zone. On the basis of the chemical composition data on rocks and minerals and estimated temperatures, the hydrothermal solutions responsible for the formation of the Seongsan dickite deposits were estimated to have the composition: $m_{K^+}=0.003$, $m_{Na^+}=0.097$, $m_{SiO_2(aq.)}=0.008$ and pH=5.0, here "m" represents the molality (mole/kg $H_2O$).

• Journal of Food Hygiene and Safety
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• v.33 no.5
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• pp.375-382
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• 2018

This study was conducted to analyze the microbial community and propionic acid production ability of natural microflora in the rice cakes. Genetic analysis of natural microflora in Jorangyi rice cake was performed to select propionic acid - producing bacteria. Selected propionic acid-producing bacteria were cultivated in TSB (tryptic soy broth) supplemented with glucose, and growth characteristics were analyzed by temperature and production of propionic acid was analyzed by gas chromatography (GC-FID). Linearity, detection limit, quantitative limit, and recovery rate were measured to verify propionic acid assay. A total of 98 microbial strains were detected from microflora of Joraengyi rice cake that grew after expiration of shelf life. Lactobacillus casei group accounted for 50.48% and Lactobacillus buchneri was 29.60%. Propionic acid - producing bacteria were Propionibacterium thoenii, P. cyclohexanicum, Propionibacterium_uc, P. jensenii, and P. freudenreichii. Natural bacteria and Lactobacillus spp. did not produce propionic acid during 14 days but P. cyclohexanicum, P. freudenreichii subsp. Shermanii, P. thoenii and P. jesenii produced $263.47{\mu}g/mL$, $338.90{\mu}g/mL$, $325.43{\mu}g/mL$ and $222.17{\mu}g/mL$ during 4 days and 2,462.02 and 2,904.78, 2,220.64, $3,519.17{\mu}g/mL$ during 14 days. As a result of this study, it was affirmed that the natural microflora of Joraengyi rice cake during storage can produce propionic acid from natural sources even if a high concentration of propionic acid is not intentionally added. Because of characteristics of rice cake composed of starch and glucose. This study will be used as a recognition criterion to detect natural preservatives such as propionic acid in starchy foods such as rice cakes and as reference standard safety management data.