• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.591-597
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• 2001

Ti alloy is used for essential parts of aircraft for high temperature environment. Although Ti alloy has excellent performance in regard to mechanical properties, it is difficult ot find fatigue cracks by nondestructive ultrasonic inspection due to its two-phase microstructure, which consists of hard alpha and beta phases. Sound energy reflected from microstructural features in the component produces a background inspection noise which is seen even when no defects are present. This noise can inhibit the detection of critical internal defects such as pores cracks or inclusions. To obtain fundamental data on ultrasonic inspection of Ti alloy, ultrasonic testing was performed using a specimen with small drill holes and ultrasonic wave propagation velocites were measured.

• 전자공학회논문지 IE
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• v.43 no.2
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• pp.63-69
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• 2006

Islanding phenomenon of utility-connected PV power conditioning systems(PV PCS) can cause a variety of problems and must be prevented. If the real and reactive powers supplied by PV PCS are closely matched to those of load, islanding detection by passive methods becomes difficult. The active frequency drift(AFD) method, called the frequency bias method, enables islanding detection by forcing the frequency of the voltage in the islanding to drift up or down. In this paper, non-detection zone(NDZ) of AFD is analyzed for the islanding detection method of utility-connected PV PCS by simulation tool PSIM.

• The Korean Journal of Pesticide Science
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• v.3 no.1
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• pp.51-56
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• 1999

For the determination of coastal environmental contamination level of benomyl, benzimidazole pesticide, the residue of benomyl in various environmental samples on the Cheju island was monitored in May, August and October 1996, respectively. The residue of benomyl was determined as carbendazim because benomyl was converted to carbendazim (methyl 2- benzimidazolecarbamate) in the environment. The qualified limit detection of benomyl was $0.2{\mu}g/L$ in ocean water and $0.4{\mu}g/kg$ in the solid such as sediment and sea organism by HPLC with UV detector. Benomyl was not detected in any water and sediment. Moreover benomyl was neither detected in seaweed cava(Ecklonia Cava), agar(Gelidium amansii), turban sell(Batillus cornutus) and sea urchin(Anthocidaris Crassispina). Above date suggest that the benomyl used in the Cheju island is not the major source of coastal contamination.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.337-342
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• 2007

To obtain the data on the risk assessment of residue levels of organophosphorus and organochlorine pesticides in fresh ginseng and red ginseng extract, the residual pesticides in samples are surveyed with GC-NPD and GC-ECD for quantitative analysis and GC-MSD for qualitative analysis. The residual organophosphorus pesticides, such as diazinon, pyrimethanil, tolclofos-methyl, metalaxyl, diethofencarb, parathion, cyprodinil, tolylfluanid and kresoxim-methyl, are not detected in fresh ginseng from Punggi. The residual organophosphorus pesticides except tolclofos-methyl are not detected in fresh ginseng from Sangju. Average amount of tolclofos-methyl in fresh ginseng from Sangju are $0.054{\pm}0.008\;mg/kg$, representing $18{\pm}2%$ of MRL of 0.03 mg/kg on fresh ginseng in Korea. The residual organochlorine pesticides, such as BHC isomer, DDT isomer, aldrin, azoxystrobin, captan, cypermethrin, deltamethrin, dieldrin, difenoconazole, endosulfan-sulfate, endrin, fenhexamid, quintozene, ${\alpha}$-endosulfan and ${\beta}$-endosulfan, are not detected in fresh ginseng from Punggi and Sangju. The residual organophosphorus and organochlorine pesticides in red ginseng extract from Punggi and Sangju are not detected.

• Korean Journal of Microbiology
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• v.38 no.3
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• pp.186-191
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• 2002

The usefulness of oligonucleotide DNA chip was evaluated for detection and primary level identification of major waterborne viruses in environmental samples. The enteric waterborne viruses included enterovirus, adenovirus, and rotavirus. Total intracellular RNA of 10 BGM cell plates showing virus-specific cytopathic effects was extracted at the third day after inoculation. The intracellular RNA was then subjected to either enterovirus-specific RT-PCR followed by sequencing analysis, or the DNA chip. Seven out of 10 positive samples in cell culture were positive but the other three sample were turned out to be negative by both RT-PCR and DNA chip analyses. Nucleotide sequencing results and the DNA chip hybridization results of the RT-PCR product were in complete agreement in the identification of the 7 positive samples as enteroviruses. Using the DNA chip, it took only 3∼4 hr to complete detection and primary level identification of target viruses and additional procedures such as gel electrophoresis or nucleotide sequencing were not necessary. We believe that the DNA chip system can be employed as a highly effective and new detection methodology for environmental viruses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.620-626
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• 2017

This study conducted chemical and physical hazard analysis on the acidity, peroxide value, color removal, and limit criteria of metal detector of roasted laver. The Hunter color L- and a-value of roasted laver was higher than the control, and the b-value was higher at $400^{\circ}C$. The limit criteria establish by metal detector was determined to a sensitivity of 60 because it detected 100% in a sensitivity of 60 to Fe and Sus. The acidity and peroxide values increased with increasing temperature. These results confirmed that roasted laver is safe when roasted to $300^{\circ}C$ for 5 seconds.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.809-814
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• 2021

This study was performed to evaluate the microbiological quality of fresh cut fruits in Korea. Forty freshly cut fruit samples were assessed for aerobic mesophilic count (AM), aerobic psychrophilic count (AP), total coliform, generic Escherichia coli, yeast and mold (YM), Bacillus cereus, Staphylococcus aureus, Salmonella spp., and E. coli O157:H7. The average value for AM, AP, and YM was 4.51, 5.35, and 4.31 log CFU/g, respectively. The average of the total coliform was 2.42 log CFU/g, and E. coli was not detected in all samples. For foodborne pathogen bacteria, B. cereus and S. aureus were detected in 2.5 and 7.5% samples, respectively, and Salmonella spp. and E. coli O157:H7 were not detected in all samples. Among the samples, pear generally had the highest contamination level. Therefore, to assure the safety of fresh cut fruits, low temperature and thorough hygiene management should be implemented.

• Analytical Science and Technology
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• v.21 no.1
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• pp.53-57
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• 2008

In order to survey the contents of ethyl carbamate in alcoholic beverages, GC/MS-SIM method was used after extraction with dichloromethane in solid phase extract cartridge contained alcoholic beverages. In the applied GC/MS-SIM method, the values of recoveries and relative standard deviation were ranged from 85.2 % to 87.9 % and from 0.7 % to 1.9 %, the limit of detection and quantification were $2{\mu}g/kg$ and $10{\mu}g/kg$. Depending on alcoholic beverage kinds, the levels were variable and the average level was $194{\mu}g/kg$ for liquor, $105{\mu}g/kg$ for fruit wine, $62{\mu}g/kg$ distilled spirit, $28{\mu}g/kg$ for sake, $15{\mu}g/kg$ for yakju, $12{\mu}g/kg$ for other alcohol beverages, ND for soju, respectively.

• Analytical Science and Technology
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• v.20 no.2
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• pp.170-175
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• 2007

To determine levels of benzopyrene in olive oils, a selective analytical method of HPLC/FLD has been applied. After removing fat in food samples with hexane, it was extracted in aqueous N,N-DMF solution, cleaned-up on florisil SPE cartridge and analyzed by the instrumental analysis. The mobile phase was a mixture of acetonitrile and water in 8:2 by the isocratic elution and the excitation wavelength of fluorescence detector was 294 nm and emission wavelength of it was 404 nm. The average recovery was about 95 % and the limit of quantitation was $0.9{\mu}g/kg$. The levels of benzopyrene in the selected olive oil samples were ranged from not detected to $1.9{\mu}g/kg$, however, they were under $2.0{\mu}g/kg$, the maximum level of benzopyrene in olive oil which was established in the food code.

• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.311-318
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• 2023

This study was performed to determine the contents of propionic, benzoic, and sorbic acids in dried seasoned seafood products (n=27) sold in Korea. Propionic acid was determined using a gas chromatogramphy-flame ionization detector. Benzoic and sorbic acid were analyzed by using a high-performance liquid chromatography-diode array detector. Benzoic acid was not detected in the dried seasoned seafood products; however, propionic and sorbic acid were detected in some samples. The concentrations of propionic acid and sorbic acid were up to 125.10 mg/kg and 658.18 mg/kg in dried seasoned seafood products, respectively. Of eight samples labeled with potassium sorbate, sorbic acid was detected in seven of them. The detected sorbic acid levels in these samples met the regulations for sorbic acid usage in Korea. The propionic, benzoic, and sorbic acid contents of dried seasoned seafood products determined in this study can provide basic data for safety management of dried seasoned seafood products in future.