• 한국축산식품학회지
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• 제24권3호
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• pp.232-237
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• 2004

본 연구는 도축장 규모 및 계절별로 도축 공정 단계에 따른 미생물학적 오염도와 변화 추이를 조사하기 위하여 수행되었다. 도축 5단계 즉, 박피 후, 내장 적출 후, 최종 세척 전, 최종 세척 후 그리고 냉장실에서 소 도체 흥부 표면에 대한 미생물학적 분석을 위하여 가로세로 10${\times}$10 cm의 면적에 대하여 swab 방법으로 시료를 채취하였다. 그 결과 겨울철 시료에 있어 대규모 도축장은 박피, 내장 적출 및 최종 세척 전까지의 도축단계에서는 $10^{0}$∼$10^2$CFU/ $\textrm{cm}^2$ 수준의 일반세균이 검출되어 $10^{0}$∼$10^3$ 수준을 보인 중소규모 도축장에 비하여 1∼2 log값이 적은 미생물이 검출되었으나, 최종세척 후($10^2$CFU/$\textrm{cm}^2$)와 냉장실($10^1$CFU/$\textrm{cm}^2$)의 미생물 검출값에 있어서는 도축장 규모에 따른 차이를 보여주지 않았다. 겨울철 시료는 봄철 시료에 비하여 도축장 규모에 차이 없이 일반세균이 1 log 값 정도 적게 검출되었다. 최종세척 공정의 시료채취 부위에 따른 세척 효과를 보기 위한 실험에서 둔부 부위에서는 세척 효과를 보여주었지만, 옆구리와 흉부 부위에서는 오히려 세척 후 미생물 수가 최종 세척 전 단계보다 증가하는 경향을 보여주었다.

• 한국식품위생안전성학회지
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• 제23권3호
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• pp.212-217
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• 2008

This survey was conducted to monitor the adulteration of sesame oil circulated in Gwangju, 2007. A total of 60 samples was tested by analysis of fatty acid composition. Of these samples, 22 were from large-scale manufacturer, 25 were from small-scale manufacturer and 13 from Bangagan. First of all, in goods manufactured by large-scale company, there are no sesame oils where linolenic acid($C_{18:3}$) exceed regulatory guidance(0.5%). 5 samples from small-scale manufacturer contained linolenic acid from 0.90% to 8.38%, which means that they have other cooking oil, such as com oil, soybean oil and rape seed oil. Among Bangagan goods, only one sample have 1.20% of linolenic acid. On the other hand erucic acid($C_{22:1}$) was not detected in 60 samples at all, which means that they were not adulterated with rape seed oil. And among 6 samples of exceeding 0.5% of linolenic acid and 12 samples from Bangagan, 13 of them had benzo(a)pyrene from $0.2{\mu}g/kg\;to\;0.7{\mu}g/kg$ and the other 5 samples did not.

• 한국주조공학회지
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• 제24권1호
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• pp.52-59
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• 2004

Microstructure and mechanical properties of ductile cast iron were investigated in terms of diameter change of samples that gives rise to modify the microstructure due to different cooling rate in the continuous casting process. The chemical composition used in this study was GCD 400 grade. From the microstructural observation, we have found a large number of graphite with small size in diameter which is comparable to the microstructure of the sample produced by conventional sand casting. The major reason of this would he due to high cooling rate. In the sample with 26 mm in diameter, the microstructure was composed of pearlite, iron carbide, and graphite. In the samples with 60 and 100 mm in diameter, however, we have observed a dissimilar microstructure that consisting of ferrite and graphite. Concerning the mechanical property, the sample with 26 mm in diameter showed higher hardness and strength compared to those samples with 60 and 100 mm in diameter. The result obtained for ductility appeared a reversal. Much more works such as inoculation, process design and chemical composition would be required in order to have a sound product even in a small diameter of samples.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.727-729
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• 2002

In this paper, we proposed quad variable rates ADPCM coding method and its implementation on C6000 DSP, which is modified from the standard ADPCM of ITU G.726 for speech quality improvement considering the environmental noise Four coding rates, 16Kbps, 24Kbps, 32Kbps and 40Kbps are used for speech window samples and the rate decision threshold is decided by the environmental noise level. The object of the proposed method is to reduce the coding rate while retaining the speech quality and the speech quality is considerably close to 40Kbps single rate coder with the coding rate close to 16Kbps single rate coder under the environmental noise. The environmental noise level affects the coding rate and the noise level is calculated per every speech window samples. At high noise level, more samples are coded at higher rates to enhance the quality, but at low noise level, only the big speech signals are coded at higher rates and more speech samples are coded at lower coding rates to reduce the coding rates. The influence of the noise on tile speech signal is considerably high for small signals and the small signal has the higher ZCR (zero crossing rate). The method is simulated in PC and to be implemented on C6000 floating point DSP board in real time operations.

• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1036-1042
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• 1998

The preconcentration and determination of trace elements in water samples were studied by a solvent sublation utilizing dithizonate complexation. After metal dithizonates were formed, trace amounts of cadmium, cobalt, copper and lead were floated and extracted into small volume of a water-immiscible organic solvent on the surface of sample solution and determined in the solvent directly by GF-AAS. Several experimental conditions as formation condition of metal-dithizonate complexes, pH of solution, amount of dithizone, stirring time, the type and amount of surfactants, N2 bubbling rate and so on were optimized for the complete formation and effective flotation of the complexes. And also four kinds of light solvents were compared each other to extract the floated complexes, effectively. After the pH was adjusted to 4.0 with 5 M HNO3, 8.0 mL of 0.05% acetone solution of dithizone was added to 1.00 L water sample. The dithizonate complexes were flotated and extracted into the upper methyl isobutylketone (MIBK) layer by the addition of 2.0 mL 0.2% ethanolic sodium lauryl sulfate solution and with the aid of small nitrogen gas bubbles. And this solvent sublation method was applied to the analysis of real water samples and good results of more than 85% recoveries were obtained in spiked samples.

• Elastomers and Composites
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• 제54권4호
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• pp.330-334
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• 2019

Cryogenic crushing techniques have been employed for recycling waste rubber articles and for extracting residual organic additives present in rubber samples. Rubber particulate derived from tire tread abrasion is one of the key components of road dust. Therefore, in this work, we prepared rubber particulates using a cryogenic crusher and characterized their shapes as well as size distributions according to the type of rubber. The rubber particulates exhibited uneven surfaces with the presence of some small pieces. The order of the particle size distribution was observed to be: NR > BR > SBR. Subsequently, carbon black was added; this led to a decrease in the particle size and the shape becoming rougher. The crushed particulates of the carbon black-filled samples comprised agglomerated shapes of small pieces, which were similar in shape to that of wear debris in tire tread. It was discovered that crosslink density was one of the principal factors that led to the formation of small crushed particulates. The small particulates obtained by cryogenic crushing can be utilized as model rubber particulates for researching micro dust.

• 한국자기학회지
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• 제9권5호
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• pp.239-244
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• 1999

란탄 망가나이트에 Bi를 첨가한 벌크 시료(La0.67xBixCa0.33MnO3(x=0, 0.04, 0.1, 0.2)들을 세라믹스 제조공정을 이용하여 제조했다. 제조한 시료들의 결정성과 미세구조를 x-선 회절분석과 광현미경으로 조사하고, 자기 및 자기저항 특성을 100~300K의 온도 범위에서 0.4~0.5T의 자기장을 인가하여 진동시료형자력계와 van der Pauw법으로 조사했다. Bi를 소량(x=0.04, 0.1) 첨가한 시료의 경우 시료를 제조할 수 있었다. 또한 Bi를 소량 첨가하는 것에 의해 측정한 대부분의 온도에서 비저항이 감소하였고 자기저항비가 증가하였다. 아울러 실온에서 약한 자기장(0.4T)하에서도 큰 자기저항비(x=0.1의 경우 15%)를 나타냈다.

• Journal of the Korean Statistical Society
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• 제19권1호
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• pp.80-87
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• 1990

In reliability and life testing the mean residual life (MRL) of an item plays a significant role. While there has been a great deal of discussion on the theoretical aspects of the MRL, good estimators of MRL have been difficult to obtain. In this paper we propose a new estimator of the MRL of items at a given age, which is especially good for a small sample. The new estimator compares favorably with the empirical MRL estimator for small samples.

• Parasites, Hosts and Diseases
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• 제56권3호
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• pp.281-285
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• 2018

Cryptosporidium is the most common protozoan that can infect a wide range of animals, including mammals and birds. Avian Cryptosporidium spp. can cause enteric and respiratory diseases which can be fatal in birds and some species are zoonotic. Companion birds have the potential as reservoir due to their close contact with humans. Pet shops are the major source of companion birds. However, few reports are available regarding Cryptosporidium spp. infection among companion birds kept in pet shops. The present study reports the prevalence and molecular characteristics of Cryptosporidium spp. among companion birds kept in pet shops in Japan. A total of 265 fresh fecal samples were obtained from birds kept in 4 pet shops; these birds belonged to 41 species in 3 bird orders. A nested polymerase chain reaction (PCR) assay targeting the small subunit rRNA gene was employed for the detection of Cryptosporidium spp. A total of 24 samples (9.1%) were positive, and Cryptosporidium spp. were detected from all pet shops. The prevalence of Cryptosporidium spp. in each of the bird orders was 6.5% (10/153) in Psittaciformes, 14.4% (13/90) in Passeriformes, and 4.5% (1/22) in Galliformes. Based on sequence analysis, 13 (54.2%) isolates were classified to C. galli, 8 (33.3%) were avian genotype III, and the remaining 3 (12.5%) were C. baileyi. No infection with zoonotic C. meleagridis and no coinfection with multiple Cryptosporidium spp. and/or genotypes were observed. The zoonotic potential of Cryptosporidium spp. infecting companion birds kept in pet shops in Japan is likely to be low.

• 한국식품저장유통학회지
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• 제18권5호
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• pp.786-794
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• 2011

국내 김치 산업체의 김치위생상태 현황을 조사하기 위하여 반찬가게김치, 중소기업김치, 대기업김치를 $10^{\circ}C$에서 10일간 발효하면서 발효시간에 김치의 일반특성 및 미생물 균총 변화를 조사하였다. 3종류 시판김치의 구입당일 pH는 평균 5.8에서 발효 10일에는 pH 4.1 부근으로 감소하였으나, 대기업김치가 다른 시판김치에 비해 발효초기 급격한 pH 감소를 나타내었다. 시판김치의 구입당일 산도는 대기업김치가 다른 두 종류의 시판김치보다 낮았으나, 발효 10일에는 세 종류의 시판김치 모두 1.1% 정도의 산도를 나타내었다. 시판김치의 염도는 중소기업김치가 다른 두 시판 김치보다 다소 높은 농도를 나타내었으며, 시판김치의 당도는 반찬가게김치가 중소기업김치와 대기업김치보다 다소 높은 당도를 나타내고 시료별 당도 차이도 크게 나타났다. 시판김치의 구입당일 총균수와 유산균의 수는 대기업 김치가 다른 두 시판김치에 비해 높은 수가 검출되었으며 발효 초기에 급격히 증가하는 경향을 나타내었다. 구입당일 시판김치 내 유산균외 그람양성 세균수는 반찬가게김치가 가장 많이 검출되었으며 중소기업김치, 대기업김치 순이었으며, 발효 10일까지 거의 비슷한 수준의 균수가 검출되었다. 시판김치의 구입당일 대장균 및 대장균군을 포함한 그람음성 세균수는 반찬가게김치가 가장 높게 검출되었으며 중소기업김치, 대기업김치 순으로 나타났다. 반찬가게김치의 그람음성 세균수는 발효가 진행됨에 따라 서서히 감소하였으나 발효 10일까지도 검출된 반면, 중소기업김치와 대기업김치는 발효 8일부터는 검출되지 않았다. 김치가 과숙됨에 따라 산도 저하와 함께 검출되는 효모는 산도0.36%이하의 익지 않은 반찬가게김치(구입당일)와 중소기업김치(발효 2일차)에서도 검출되었으나, 대기업김치는 산도가 0.96% 이상인 발효 8일째부터 검출되었다. 제조회사별 김치에 존재하는 유산균을 제외한 그람양성균으로는 Bacillus 속이, 그람음성균으로는 E. coli, Enterobacter 속, Sphingomonase 속, Stenotrophomonas 속 등이 공통적으로 검출되었으며 그 분포는 시판김치에 따라 다소 상이하였다. 이상의 결과로부터 김치의 세계화와 김치의 산업화를 위해서는 김치의 제조관리에 보다 위생적이며 체계적으로 매뉴얼화된 생산공정 확립과 관리가 필요함을 알 수 있다.