• 한국축산식품학회지
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• 제38권2호
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• pp.282-290
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• 2018

This research was to evaluate microbial contamination levels in meat samples at hazard analysis critical control point (HACCP)-implemented processing plants that produce beef, pork, and chicken. During a period of about a year, a total of 178 samples (76 from beef, 89 from pork, and 13 from chicken) were obtained from raw materials (21.3%) and final products (78.7%). All samples were determined for each 25 g homogenized one. Samples were analyzed to determine the total aerobic plate count (APC), coliform count (CC), and E. coli count (ECC). By month, APC levels were the highest in September and the lowest in February (p<0.001). In comparison among season, APC levels in meat samples were the highest in the summer and the lowest in winter (p<0.001). By month, the highest CC prevalence was found in August, followed by October and then July (p<0.001). By season, the highest CC was obtained in summer, followed by autumn and then spring (p<0.001). All samples were negative for ECC. There was a direct correlation between the product form and coliform presence (p<0.001). In addition, there was a positive correlation between the APC and CC (r=0.261). The APCs in analyzed samples ranged from below <$10^1CFU/g$ to <$10^7CFU/g$. In conclusion, the month and season had significant effects on microbial contamination levels at HACCP implemented processing plants. Interrelationships between (i) the product form and coliform, (ii) the APC and CC were revealed.

• Journal of Astronomy and Space Sciences
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• 제12권2호
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• pp.234-243
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• 1995

1997년 10월에 발사 예정인 과학 로켓 3호는 고도 160km까지 도달할 것이 예상되므로 한반도 상공의 전리층 E 영역에 존재하는 플라즈마를 직접 측정할 수 있는 좋은 기회를 제공한다. 한펀 플라즈마 측정에 있어서 가장 기본이 되는 검출기인 Langmuir 탑침을 실험실에서 사용하는 방법 그대로 우주 실험에 적용하면 탐침의 오염으로 인해 정확한 플라즈마 실험이 불가능해 진다. 본 논문에서는 로켓용 탑침 제작에 앞서 실험실용 탐침을 제작하여 진공 용기에서 플라즈마 실험을 수행함으로써 탐침의 오염 문제를 연구하였다. 그 결과, 플라즈마의 밀도가 낮을수록 오염에 의한 효과는 적었으며 탐침에 제공되는 쓸기전압의 주파수가 증가할수록 오염에 의한 효과를 줄일 수 있었다. 이러한 연구 결과를 바탕으로 로켓 실험에 적당한 변형된 형태의 Langmuir 탐침을 제안하였다.

• 대한토목학회논문집
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• 제39권1호
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• pp.203-209
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• 2019

현재 많은 국내 산업단지들은 여러 가지 중금속오염에 노출되어있다. 이러한 오염은 토양과 지하수에 심각한 오염을 초래할 수 있다. 산업단지의 하부지반을 제올라이트를 토양과 섞은 혼합물로 대체하여 이러한 오염을 방지하고자 한다. 혼합물들을 성토재를 사용하기 위해서는 최소한의 지지력을 갖춰야 한다. 제올라이트 혼합물의 중금속(아연, 납)에 대한 흡착특성과 지지력을 실험하기 위하여 등온 흡착시험, 직접 전단시험, 및 표준다짐시험을 실시하였다. 실험결과, 혼합물들은 효과적으로 오염물질의 확산을 줄일 수 있고 동시에 적절한 지지력을 확보할 수 있다.

• 문화기술의 융합
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• 제9권2호
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• pp.561-568
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• 2023

콘크리트 구조물은 대내외적 환경에 의해 다양한 결함이 발생한다. 결함이 있는 경우 콘크리트의 구조적 안전성에 문제가 있어 이를 효율적으로 파악하여 유지관리하는 것이 중요하다. 하지만, 최근 딥러닝 연구는 콘크리트의 균열에 초점이 맞추어져 있어, 박락과 오염 등에 대한 연구는 부족하다. 본 연구에서는 라벨링이 어려운 박락과 오염에 초점을 맞추어 언라벨 방법, 필터링 방법, 전이학습과 k-means cluster의 융합을 통한 4개의 모델을 개발하고 성능을 평가하였다. 분석결과, 융합모델이 결함을 가장 세밀하게 구분하였으며, 직접 라벨링을 하는 것보다 효율성을 증가시킬 수 있었다. 본 연구 결과가 향후 라벨링이 어려운 다양한 결함 유형에 대한 딥러닝 모델 개발에 기여할 수 있기를 기대한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.310-313
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• 2002

Structures obtained with a direct boning of two FZ silicon wafers joined in such a way that a smooth surface of one wafer was attached to the grooved surface of the other were studied. A square net of grooves was made with a conventional photo lithography process. After high temperature annealing the appearance of voids and the rearrangement of structural defects were observed with X-ray diffraction topography techniques. It was shown that the formation of void free grooved boundaries was feasible. In the cases when particulate contamination was prevented, the voids appeared in the grooved structures could be eliminated with annealing. Since it was found that the flattening was accompanied with plastic deformation, this deformation was suggested to be intensively involved in the process of void removal. A model was proposed explaining the interaction between the structural defects resulted in "a dissolution" of cavities. The described processes may occur in grooved as well as in smooth structures, but there are the former that allow to manage air traps and undesirable excess of dislocation density. Grooves can be paths for air leave. According to the established mechanisms, if not outdone, the dislocations form local defect arrangements at the grooves permitting the substantial reduction in defect density over the remainder of the interfacial area.

• 대한기계학회논문집B
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• 제24권6호
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• pp.753-759
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• 2000

Photoelectric charging is a very efficient way of charging small particles. This method can be applied to combustion measurement, electrostatic precipitator, metal separation and control of micro-contamination. To understand the photoelectric charging mechanism, particle charging of silver by exposure to ultraviolet is investigated in this study. Average charges and charge distributions are measured at various conditions, using two differential mobility analyzers, a condensation nucleus counter, and an aerosol electrometer. The silver particles are generated in a spark discharge aerosol generator. After that process, the generated particles are charged in the photoelectric charger using low-pressure mercury lamp that emits ultraviolet having wavelength 253.7 nm. The results show that ultra-fine particles are highly charged by the photoelectric charging. The average charges linearly increase with increasing particle size and the charge distribution change with particle size. These results are discussed by comparison with previous experiments and proposed equations. It is assumed that the coefficient of electron emission probability is affected by initial charge. The results also show that the charge distribution of a particle is dependent on initial charge. Single changed particle, uncharged particle and neutralized particle are compared. The differences of charge distribution in each case increase with increasing particle size.

• 상하수도학회지
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• 제18권6호
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• pp.801-806
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• 2004

The pilot study was conducted to (i) investigate the ability of various membrane integrity monitoring methods to detect changes in membrane integrity during operation, and (ii) determine the impact of membrane damage on microbial removal by microfiltration. Two variations of air pressure hold tests were investigated for direct integrity monitoring: pressure decay (PD) and diffusive air flow (DAF) tests which are most commonly used integrity tests for microfiltration (MF) membranes. Both PD and DAF tests were sensitive enough to detect one damaged fiber out of 66,000 under field operaing conditions. Indirect integrity monitoring such as turbidity and particle counting, however, responded poorly to defects in membrane systems. Microbial challenge study was performed using both new and deliberately damaged membranes, as well as varying the state of fouling of the membrane. This study demonstrated that MF membrane with nominal pore size $0.2{\mu}m$ was capable of removing various pathogens including coliform, spore, and cryptosporidium, at the level required by drinking water regulations, even when high operating pressures were applied. A sharp decrease in average log reduction value (LRV) was observed when one fiber was damaged, emphasizing the importance of membrane integrity in control of microbial contamination.

• Journal of Microbiology
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• 제44권2호
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• pp.162-170
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• 2006

Oysters are known to be carriers of food-born diseases, but research on viruses in Korean oysters is scarce despite its importance for public health. We therefore tested oysters cultivated in Goheung, Seosan, Chungmu, and Tongyeong, for viral contamination using cell culture and integrated cell culture PCR (ICC-PCR) with Buffalo green monkey kidney (BGMK) and human lung epithelial (A549) cells. Additional screens via PCR, amplifying viral nucleic acids extracted from oysters supplemented our analysis. Our methods found 23.6 %, 50.9 %, and 89.1 % of all oysters to be positive for adenoviruses when cell culture, ICC-PCR, and direct PCR, respectively, was used to conduct the screen. The same methodology identified enteroviruses in 5.45%, 30.9%, and 10.9% of all cases. Most of the detected enteroviruses (81.3%) were similar to poliovirus type 1; the remainder resembled coxsackievirus type A1. A homology search with the adenoviral sequences revealed similarities to adenovirus subgenera C (type 2, 5, and 6), D (type 44), and F (enteric type 40 and 41). Adenovirus-positive samples were more abundant in A549 cells (47.3%) than in BGMK cells (18.2 %), while the reverse was true for enteroviruses (21.8 % vs. 14.5 %). Our data demonstrate that Korean oysters are heavily contaminated with enteric viruses, which is readily detectable via ICC-PCR using a combination of A549 and BGMK cells.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3279-3281
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• 1999

This paper describes a method of direct wafer bonding using surfaces activated by a radio-frequency hydrogen plasma. The hydrogen plasma cleaning of silicon in the RIE mode was investigated as a pretreatment for silicon direct bonding. The cleaned silicon surface was successfully terminated by hydrogen, The hydrogen-terminated surfaces were rendered hydrophilic, which could be wetted by Dl water rinse. Two wafers of silicon and silicon dioxide were contacted to each other at room temperature and postannealed at $300{\sim}1100^{\circ}C$ in an $N_2$ atmosphere for 2 h. From the AFM results, it was revealed that the surface became rougher with the increased plasma exposure time and power. The effect of the plasma treatment on the surface chemistry was investigated by the AES analysis. It was shown that the carbon contamination at the surface could be reduced below 5 at %. The interfacial energy measured by the crack propagation method was 122 $mJ/m^2$ and 384 $mJ/m^2$ for RCA cleaning and hydrogen plasm, respectively.

• 한국토양비료학회지
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• 제45권2호
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• pp.287-292
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• 2012

누출검사와 자체정밀조사 결과를 토대로 살펴본 국내의 석유류 시설에 대한 객관적인 현황 및 실태 조사 결과는 다음과 같다. 국내 특정토양오염관리대상시설을 업소단위로 평가한 결과 부적합률은 약 53.6%로 누출검사 평균 부적합률 3.1%에 비해 약 17.3배 높다. 특정토양오염관리대상시설의 점검방식별 부적합률은 직접법은 58.9% 그리고 간접법은 22.5%였다. 직접법에 의해 확인된 용접부 결함과 간접법 점검 시 확인되지 않는 배관계통의 누설을 포함한 부적합률은 최대 58.9%까지 증가한다. 실제 특정토양오염관리대상시설로부터 누출이 확인된 업소는 30.7%였으며, 저장탱크 주유배관 주입배관 등에서 누출이 확인되어 당해 시설로부터 오염물질이 외부로 유출되고 있는 업소는 25.7%였다. 특정토양오염관리대상시설의 소유자가 자발적 점검에 의한 부적합률은 57.3%인 반면, 강제적 부적합율은 17.2%로 자체점검 결과가 국내 특정토양오염관리대상시설의 현황에 가깝다고 판단된다. 특정토양오염관리대상시설을 구성하는 시설별 조사결과 각 시설의 부적합률은 저장탱크의 경우 누출 2.6%, 비누출을 포함한 부적합률은 22.2%였으며, 주입배관 4.1%, 주유배관 5.5%, 통기관 10.3%로 나타났다. 저장탱크의 부적합 사유별 요인은 균열 및 기공 17.9%, 미용접 5.3%로 전체 대상 탱크의 약 20%가 당해 저장탱크 제작 시부터 잠재적 누출요인을 안고 있는 것으로 추정되며, 부식 또는 국부적으로 진행된 공식 등으로 석유류저장탱크의 최소두께 (3.2 mm)에 미달되어 부적합 판정된 6.6%의 탱크가 내구연한을 초과하거나 도래하고 있는 것으로 판단된다.