• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.10a
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• pp.310-316
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• 2005

축산식품(우유)내의 잔류항생물질을 신속하고 간편하고 정확하게 분석하기 위한 시험법 개발을 목적으로 하였다. 축산식품내의 일반적인 잔류항생물질에 대한 지금까지의 분석법으로는 Bioassay법, TLC법, ELISA법, GC법 및 HPLC법 등이 있지만 Streptomycin/dihydrostreptomycin, neomycin에 대한 HPLC법은 거의 확립되어 있지 않은 실정이다. 우리나라의 공인 검사법으로는 Bioassay법 및 HPLC법등이 있지만 그러나 지금까지의 방법으로는 검출감도가 낮은 것이 큰 문제점으로 되어 왔다. 본 연구에서는 STP에 대한 HPLC법에 대한 보고한 Edder 방법 중에 clean-up 과정 및 이동상 조건을 대폭 수정하여 STP의 분리 및 검출감도를 낮추려고 시도하였다. 본 연구에 사용된 유도체화 장치 Post-Column Derivatization Instrument PCX 5100 (Pickering La-boratories, Inc.)의 컬럼 온도는 $40^{\circ}C$, 오븐온도 $55^{\circ}C$, 유도체화 용매 유속 0.6ml/min 이동상 유속 0.8ml/min으로 검출기는 형광검출기를 이용하여 STP 검출에 대해 만족할 만한 결과를 얻었다. 이때의 분석소요시간은 약 15분이었다. 표준시료 STP의 검량선은 넓은 농도범위(0.02${\sim}$1.0ppm)에서 양호한 직선성을 나타냈다. 본 시험법에 의한 검출한계는 limit of detection(LOD)은 0.02ppm이었으며, 적어도 우유에서의 MRL이 0.6ppm임을 감안하면 STP를 정량적으로 정도 좋게 측정할 수 있다는 것을 확인했다. 상기의 조건하에서 실제시료인 우유에 표준 STP를 0.5ppm을 spiking한 후 SPE상에서 SCX(Strong cation exchange column)을 통한 clean-up과정을 거친 후의 STP의 limit of quantification(LOQ)는 약 0.44ppm이었으며, 이에 대한 회수율은 89.7${\pm}$2.3%(n=6)를 나타냈다. 실제 CODEX에서 권장한 우유의 MRL이 0.6ppm인 점을 감안하면 CODEX권고치에 도달할 수 있는 것으로 판단되었다. 따라서 본 연구에서 개발 된 시험법은 지금까지 국내적으로 STP에 대한 시험법이 확립되어 있지 않은 것으로 이와 아울러 간편한 parallux와 병용해 STP에 대한 정량 및 정성 분석을 유도체화 장치 및 형광검출기를 이용해 잔류항생물질 STP에 대한 분석시험법을 개발하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10C
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• pp.1010-1015
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• 2009

In this paper, we propose a novel detection ordering technique for MIMO signal detection methods based on QR decomposition and successive interference cancellation (SIC). Recently, new signal detection methods for spatially multiplexed (SM) MIMO systems were proposed, where all the constellation points are tried as the first layer symbol, and the remaining layer symbols are estimated via SIC, producing candidate vectors. Finally, the ML metric values are calculated for the candidate vectors, that are again used to select the best symbol vector. It was also shown that the ordering method in the conventional V-BLAST is not suitable to these signal detection methods. In this paper, we propose a novel ordering method, and we show via computer simulations that the proposed ordering method improves the error performance.

• Journal of Life Science
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• v.13 no.6
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• pp.799-804
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• 2003

In order to verify the occurrence of an estrogenic compound in natural products, the estrogenic activity was measured using an in vitro detection system. For this system, human breast cancer cell line MCF7 was transfected using an estrogen responsive CAT reporter plasmid. Estrogenic activities of photosynthetic algae spirulina and sea lettuce were evaluated using this system. Estrogenic activities of a $500\mug/ml\; and\; 50 \mug/ml$ ethanol extracts of spirulina were as much as that of $10^{-8}$M standard solution (17$\beta$-estradiol) and activity of $5\mug/ml$ ethanol extract of spirulina was as much as that of $10^{-10}$ M standard solution. However, no significant estrogenic activity was observed using sea lettuce extract. Estrogenic activities of marine animals, such as star fish and shrimp, were also evaluated using this system, however, no significant estrogenic activity was observed in these extracts. In this result, it is confirmed that spirulina extract possesses estrogenic compound.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.821-831
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• 2021

In order to calibrate energy and efficiency using the PENELOPE Code, a PENELOPE simulation was performed using a volume source. Here, we want to verify peak efficiency and usefulness by performing simultaneous measurement and correction. calculate the coincident sum correction for all volumes, first subdivide the volumes of the cylinder and the four Marinelli beakers into three heights again. Therefore, the simultaneous measurement correction coefficient in three areas and the simultaneous measurement correction coefficient for the entire volume source are calculated as output. At low energies, the j value for each source volume (50-300 ml) is small and increases significantly in the high energy range. Simulation results showed good agreement within 2.5% for all source volumes except for 50 ml and 300 ml, which were up to 4%. This means that the correction for the simultaneous measurement effect during measurement is effective. In addition. Based on this, it can be confirmed that there is an advantage to improve the detection efficiency when measuring various sources and environmental samples.

• Analytical Science and Technology
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• v.20 no.3
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• pp.237-245
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• 2007

The presence of benzene in 31 products of vitamin drinks purchased from 20 retail outlets was determined using headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The sample (25 ml) was stirred at 1200 rpm for 4 min using a magnetic bar with a $100{\mu}m$ SPME fiber as an adsorbent for benzene which was then desorbed from the fiber for 1 min in the GC injector. Quantitation was achieved using the standard addition method. The limit of detection was determined as 0.56 ng/ml and over a concentration range 0-40 ng/ml the coefficient of correlation was greater than 0.999. The concentration of benzene in the drinks examined was in the range not detectable to 47.35 ng/ml. Benzene was detected in 15 of the drinks with concentration in 5 of them greater than 10 ng/ml which is the limit set for the presence of benzene in the Drinking Water Regulations. The concentrations of benzene in the 5 drinks which exceeded the limit of 10 ng/ml were 16.99, 35.14, 16.03, 47.35 and 14.28 ng/ml respectively.

• Journal of dental hygiene science
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• v.15 no.2
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• pp.232-237
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• 2015

The water supplied from dental unit water systems (DUWS) in dentistry may be heavily contaminated with bacteria and thus may be a potential source of infection for both practice staff and patients. The aim of this study was to evaluate the level of heterotrophic bacteria and to confirm the presence of opportunistic pathogens from DUWS in student clinical simulation laboratory of college of dentistry. Water samples were collected from 36 ultrasonic scalers in student clinical simulation laboratory. The levels of heterotrophic bacteria in water samples were quantified by counting colony forming units (CFUs) on R2A agar media. In addition, opportunistic pathogens were detected by using the polymerase chain reaction (PCR) method. The mean CFUs were 16,095 CFU/ml for water samples and all of water samples exceeded current American Dental Association recommendations of 200 CFU/ml. Pseudomonas species and non-tuberculous Mycobacterium species were detected in the one sample and two samples, respectively, among the 36 water samples by the PCR with specific primers for these bacteria. Our study indicated that DUWS in student clinical simulation laboratory can cause potential infection in students and participants. This study suggested the dental unit water line management and wearing personal protective equipment in student clinical simulation laboratory will be needed to reduce bacterial contamination.

• Research in Plant Disease
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• v.9 no.2
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• pp.94-98
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• 2003

To produce antibodies against Pseudomonas tolaasii and P. agarici, lyophilized P. tolaasii and P. agarici ($5{\times}10^7$ cfu/ml) and Freund, s adjuvant were immunized into rabbits 4 times. The specificity and sensitivity of the antibodies were evaluated by immunodiffusion test and indirect enzyme-linked immunosorbent assay (id ELISA). The ${\alpha}$-P. tolaasii antibody was very specific only against P. tolaasii, while ${\alpha}$-P. agarici antibody was not specific and showed a high cross reactivity toward P. tolaasii with detection limit concentration of $2{\times}10^3$ cfu/ml. However, the cross reactivities of ${\alpha}$-P. agarici antibody toward the related species including P. reactans were very low. Our results showed that ${\alpha}$-P. tolaasii and ${\alpha}$-P. agarici antibodies against P. tolaasii and P. agarici, respectively, might be useful for rapid and simple detection of the causal agents of bacterial brown and yellow blotches in cultivated oyster mushrooms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.403-410
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• 2008

In this paper, we propose a variant of the QRM-MLD signal detection method that is used for spatially multiplexed multiple antenna system. The original QRM-MLD signal detection method combines the QR decomposition with the M-algorithm, thereby significantly reduces the prohibitive hardware complexity of the ML signal detection method, still achieving a near ML performance. When the number of transmitter antennas and/or constellation size are increased to achieve higher bit rate, however, its increased complexity makes the hardware implementation challenging. In an effort to overcome this drawback of the original QRM-MLD, a number of variants were proposed. A most strong variant among them, in our opinion, is the ranking method, in which the constellation points are ranked and computation is performed for only highly ranked constellation points, thereby reducing the required complexity. However, the variant using the ranking method experiences a significant performance degradation, when compared with the original QRM-MLD. In this paper, we point out the reasons of the performance degradation, and we propose a novel variant that overcomes the drawbacks. We perform a set of computer simulations to show that the proposed method achieves a near performance of the original QRM-MLD, while its computational complexity is near to that of the QRM-MLD with ranking method.

• Journal of Food Hygiene and Safety
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• v.18 no.3
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• pp.118-124
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• 2003

For the rapid detection of various pathogenic microorganisms from food sample, various kinds of kits have been developed and commercially available in the markets. With the advantages of speed, accuracy and easiness, the market of these kits has gradually increased for the QC and QA field of food company as well as testing facilities or laboratories. In this study, the characteristics such as the detection limit and the sensitivity of immunochromatographic type of rapid detection kit (Donga Co, Korea, D-kit) for E. coli 0157:H7 developed by monoclonal antibody were examined and also the possibility of application of the kit to food samples was evaluated. The reference kits used for comparison study were Reveal E. coli 0157:H7 (Neogen Co., USA, R-kit) and VIP EHEC kit (Biocontrol Inc., USA, V-kit) occupying major market share. In the detection limit test with the E. coli 0157:H7 reference, both R-kit and D-kit showed a distinct positive reaction in $10^4$/ml and weak positive reaction in $10^3$/ml, whereas V-kit showed a same reaction in 105/ml. Also, it was identified that the culture treated with heat showed more sensitivity than no heat treated culture. The sensitivity test was conducted against 22 isolates of E. coli 0157:H7, 7 strains of non-O157:H7 verotoxin-producing E. coli, 40 strains of E. coli with different O and H antigen type, and 38 strains of non-E. coli Enterobacteriaceae, and all of the test strains except three were showed exactly three were showed exactly the same reaction against three kinds of the tested kits. All the three kinds of kits showed a positive reaction against E. coli O157:H19, E. coli O148:H18 and Salmonella galinarium. We suppose that there might be a similarity in serological property between these three strains and O157:H7. From the test results, it can be concluded that there is (was) no difference between the D-kit developed in this study and R-kit or V-kit based on the detection limit and sensitivity.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.244-250
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• 2008

To evaluate bacteriological water quality, samples were taken from drinking water dispensers placed at S company (S-C) and U highschool (U-H) in Ulsan. The medians of heterotrophic plate counts (HPCs) were 53 CFU/ml for the 74 water samples of S-C and 80 CFU/ml for the 36 cold water samples of U-H, and 38% of the S-C and 42% of the U-H samples showed HPC bacterial concentrations higher than 100 CFU/ml. Coliform bacteria were detected from one sample of S-C. To determine the major source of bacterial contamination, water samples were taken daily for $6\sim8$ days from the bottled water containers as well as the faucets of an experimental water dispenser. While the average HPCs in the bottled water containers were 33 CFU/ml for the first and 132 CFU/ml for the 2nd analysis, the HPC concentration in the cold water samples was 1,022 CFU/ml for the 2nd analysis. These results suggest that the majority of bacteria detected in the cold water samples were originated from the biofilms on the surface of water passages within the water dispensers. There was no significant increase in HPC bacterial concentrations within the bottled water container after installation on the water dispenser. We could isolate and tentatively identify 3 genera 6 species of Gram-positive and 7 genera 7 species of Gram-negative bacteria from the plate count agar plates of U-H samples. Among the isolates, 72% were observed as Gram-positive, and Micrococcus spp. was the most abundant with 54% of the total, followed by Sphingomonas paucimobilis with 16%. It appears that most of the HPC bacteria detected in water dispensers originate from indoor airborne bacteria, which may play important roles in the formation of biofilms on the surface of water passages within the water dispensers.