• Structural Engineering and Mechanics
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• 제62권2호
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• pp.197-208
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• 2017

Among various retrofitting strategies, use of semi-active control for retrofitting a building structure has gained momentum in recent years. One of the techniques for such retrofitting is to connect a weaker building to an adjacent stronger building by semi-active devices, so that performances of a weaker building are significantly improved for seismic forces. In this paper, a ten storey weaker building is connected to an adjacent stronger building using magneto-rheological (MR) dampers, for primarily improving the performance of the weaker building in terms of displacement, drift and base shear. For this, a fuzzy logic controller is specifically developed by fuzzyfying the responses of the coupled system. The performance of the control strategy is compared with the passive-on and passive-off controls. Pounding Mitigation between the two buildings is also investigated using all three control strategies. The results show that there exists a fundamental frequency ratio between the two buildings for which maximum control of the weaker building response takes place with no penalty on the stronger building. There exists also a fundamental frequency ratio where control of the weaker building response is achieved at the expense of the amplification of the stronger building. However, coupling strategy always improves the possibility of pounding mitigation.

• Elastomers and Composites
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• 제45권3호
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• pp.212-216
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• 2010

리튬 이온 전지의 가스켓 재료로 사용되기 위해서는 내전해액성, 전기절연성, 낮은 압축 영구 줄음률, 비오염성, 내열성이 요구된다. Perfluoroalkoxy (PFA)보다 압축 영구 줄음률이 우수한 고무의 적합성을 평가하기 위하여 Ethylene Propylene Diene Monomer (EPDM), Nitrile Butadiene(NBR), Fluoro Elastomers(FKM), Methyl-Vinyl Silicone Rubber (VMQ), Fluorosilicone(FVMQ)을 이용하여 최적상태의 compound를 제작하고 특성을 살펴보았다. 시험편을 $80^{\circ}C$의 propylene carbonate액에 침적하여 경도 및 체적변화를 1,000시간까지 시간별로 측정하였다. EPDM과 VMQ가 내전해액성이 우수하였으며, 전기절연성에서도 체적저항 기준 $10^{10}{\Omega}cm$이상의 결과를 얻을 수 있었다. 따라서, EPDM과 VMQ가 적절한 것으로 판단되었다.

• Journal of Astronomy and Space Sciences
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• 제32권1호
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• pp.81-89
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• 2015

In this paper, we describe the development of a bioreactor for a cell-culture experiment on the International Space Station (ISS). The bioreactor is an experimental device for culturing mouse muscle cells in a microgravity environment. The purpose of the experiment was to assess the impact of microgravity on the muscles to address the possibility of long-term human residence in space. After investigation of previously developed bioreactors, and analysis of the requirements for microgravity cell culture experiments, a bioreactor design is herein proposed that is able to automatically culture 32 samples simultaneously. This reactor design is capable of automatic control of temperature, humidity, and culture-medium injection rate; and satisfies the interface requirements of the ISS. Since bioreactors are vulnerable to cell contamination, the medium-circulation modules were designed to be a completely replaceable, in order to reuse the bioreactor after each experiment. The bioreactor control system is designed to circulate culture media to 32 culture chambers at a maximum speed of 1 ml/min, to maintain the temperature of the reactor at $36{\pm}1^{\circ}C$, and to keep the relative humidity of the reactor above 70%. Because bubbles in the culture media negatively affect cell culture, a de-bubbler unit was provided to eliminate such bubbles. A working model of the reactor was built according to the new design, to verify its performance, and was used to perform a cell culture experiment that confirmed the feasibility of this device.

• 한국토양비료학회지
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• 제42권5호
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• pp.323-329
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• 2009

This study was conducted to analyze growth responses of fast growing tree species(8 clones of hybrid poplars, Salix alba, Metasequoia glyptostroboides, Liriodendron tulipifera, Acer okamotoanum, and Quercus palustris), the chemical characteristics of soil and $NO_3-N$ concentration of groundwater in a plantation applied with liquid pig manure. Concentrations of nitrogen and phosphorous in the soil treated with liquid pig manure were higher than that of the soil treated without liquid pig manure. With the exception of S. alba, DBH(Diameter at Breast Height) growth of all the fast growing tree species treated with liquid pig manure was higher than that of the species treated without liquid pig manure. In liquid pig manure treatment group, P. euramericana 'Eco28' clone showed the best performance in height and DBH growth. Concentration of nitrogen in the leaf with liquid pig manure was higher than that of the leaf treated without liquid pig manure. Based on the $NO_3-N$ concentration of groundwater analyzed during the experimental period, there was no evidence that groundwater was polluted by the liquid pig manure applied at the plantation.

• 정보보호학회논문지
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• 제29권4호
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• pp.785-794
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• 2019

최근 4차 산업 혁명 기술 중 하나인 딥러닝(Deep Learning) 기술은 보안 분야에서는 탐지하기 어려운 네트워크 데이터의 숨겨진 의미를 식별하고 공격을 예측하는 데 사용되고 있다. 침입탐지에 사용될 딥러닝 알고리즘을 선택하기 전에 데이터의 속성과 품질 분석이 필요하다. 학습에 사용되는 데이터의 오염여부에 따라 탐지 방법에 영향을 주기 때문이다. 따라서 데이터의 특징을 파악하고 특성을 선정해야 한다. 본 논문에서는 네트워크 데이터 셋을 이용하여 악성코드의 단계적 특징을 분석하고 특성을 추출하여 딥러닝 모델을 적용하였을 때 각 특성이 성능에 미치는 영향을 분석하였다. 네트워크 특징에 따른 특성들의 비교에 대한 트래픽 분류 실험을 진행하였으며 선정한 특성을 기반으로 96.52% 정확도를 분류하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권5호
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• pp.36-50
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• 2023

Soil health can deteriorate through both contamination and remediation. Accordingly, revitalization processes are needed to reuse or recycle the remediated soil. The study was conducted to assess the changes in soil health parameters of heavy metals-contaminated soil during soil washing process. In addition, unit processes were proposed to improve the quality of the remediated soil relevant to its reclamation purposes, such as agricultural and forest lands. A total of 21 indicators were used to determine whether the soil health was degraded or recovered. The performance of 6 amendments in improving soil health was quantitatively evaluated according to their dosage and application duration. Finally, the experimental results were assessed by simple regression analyses to determine the statistical significance and relative performance of each amendment. The results indicated that 18 health indicators out of 21 deteriorated through the soil washing process. Based on the results, it is recommended that several effective amendments be complementarily combined and applied in real applications because use of single amendment does not likely improve the quality of remediated soils.

• 한국식품조리과학회지
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• 제27권2호
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• pp.45-59
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• 2011

This study was conducted to investigate employee food-hygiene and nutrition awareness and performance and to study the current education programs for children at child care centers and kindergartens located in Seoul, Republic of Korea. A self-evaluated type of questionnaire was developed for foodservice employees and teachers using a five-point Likert scale. Employees with an employment history of <1 year and who were <30 years old had the lowest scores for food-hygiene and nutrition awareness and performance. Employees with a cooking license had a higher awareness score regarding cross-contamination than those without a license. Higher nutritional awareness and performance scores were also observed for employees who had more experience as cooks and who had received a nutrition education than those who did not. Approximately 94% and 76.4% of the employees had experience in sanitation and nutrition education, respectively. Most teachers responded that food sanitation-nutrition education for children seemed necessary in a child-care center; however, only 63.9% of the teachers actually taught sanitation-nutrition education to children. The biggest limitation to conduct food sanitation-nutrition education was the "lack of professionalism" of teachers, because only 48.1% of teachers had received a sanitation- utrition education. Thus, a food sanitation-nutrition education program for foodservice employees and teachers must be developed and implemented actively to improve the quality of food service and nutrition education in child care centers and kindergartens.

• 한국미생물·생명공학회지
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• 제43권3호
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• pp.259-266
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• 2015

온난화, 고령화, 세계화로 인하여 변화하는 국내 보건환경에 현행 수질기준이 적합할 지 평가가 필요하다. 본 연구는 총대장균군 만으로 규정된 현행 온천수 수질기준의 타당성을 환경유래 내열성세균인 레지오넬라균 오염도를 검출로 평가하였다. 온천수에서 레지오넬라균을 검출한 7개의 논문에 보고된 미생물 자료에 대한 메타분석을 실시하였다. 레지오넬라균의 검출 유무의 오즈비는 총대장균군과 유의한 상관도를 보였다[odds ratio (OR), 3.1 (1.5−6.4, 95% CI), p = 0.002]. 그러나, 레지오넬라균 오염을 분변성 중온균인 총대장균군 지표가 감지할 수 있다는 점은 단순히 설명되지 않기에, 그 기작을 검토하였다. 레지오넬라균의 검출 유무는 일반세균수와 더 높은 오즈비를 보였고[4.0(2.2−7.2), p < 0.001], 40°C 미만의 수온범위에서 수온과 강한 상관도[OR, 4.3(1.4−13.6), p = 0.011], 50°C 이상에서는 수온과 음의 상관도를 보였다[OR, 0.2 (0.1−0.4), p < 0.001]. 따라서, 수온에 의하여 세균의 현존량이 결정되는 현상 때문에 총대장균군수와 레지오넬라균 유무가 연관성을 가진 것으로 판단된다. 이에 따르면, 총대장균군보다 일반세균수가 더 직접적으로 비분변성 병원체의 증감을 반응할 것으로 생각되므로, 일반세균수를 단일 수질관리 기준으로 사용하거나, 현행 기준에 일반세균수를 추가하는 것이 타당한 것으로 판단된다.

• 한국산학기술학회논문지
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• 제19권1호
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• pp.603-608
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• 2018

전압 인가식 제전방식이 반도체나 디스플레이 산업에는 가장 많이 사용되고 있지만, 방전에 의한 주변 미세 먼지의 흡착 및 전극핀의 오염으로 불량 발생의 원인을 제공하므로, 주기적인 관리 비용이 발생하게 된다. 전극핀의 오염 문제는 코로나 방전으로 인하여, 주변 공기의 미세한 입자를 축적함으로 생성된다. Fuzz ball의 생성은 전극핀의 마모를 촉진 시키고, 또한 정전기 제거 장치의 성능을 저하시킨다. 오염물 제거 방법은 수동 브러쉬 및 자동 브러쉬를 이용하여 기계적인 세척 방법이 효과적이지만, 추가적인 기계부품이나 사용자의 관리를 요구한다. 일부의 경우에는 이미터에 축척된 오염물이 웨이퍼나 제품에 전이될 수도 있다. 이러한 문제를 해결하기 위해, 제전기의 외부로 돌출되는 전극핀을 없애고, 이온탱크 내부에 위치한 텡스텐 전극선을 이용하여 주위 기체 분자를 직접 이온화할 수 있는 청정 환경에 적합한 정전기 제거 장치를 개발하였다. 한국기계연구원에서 시험인증한 결과, 오염 입자는 평균 $0.7572particles/ft^3$이고, 제전 시간은 2초 이하 이며, 잔류 전위는 7.6V로 만족할 만한 결과를 얻었다.

• 한국환경보건학회지
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• 제11권2호
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• pp.41-54
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• 1985

This study was conducted for the improvement of milk quality and milk hygiene in public health point of view. Investigation of mastiris infection rate, isolation and identification of causative microorganisms in CMT positive milk, investigation of milk contamination level by measuring the bacteria and soma tic cell counts and investigation of dairy management in farms were performed on 1.605 quarters milk of 434 cows of 20 dairy farms in Gyunggi-area from September 1983 to March 1984. The results were summarized as follows 1. Sixteen (3.7%) of 434 cows were found to be infected with clinical mastiris. 234 (53.9%) of 434 cows and 608(37.9%) of 1, 605 quarters were found to be infected with subclinical mastiris. 2. The causative microorganisms isolated were Staphylococcus aureus (38.3%), Staphylococcus epidermidis(21.0%), Micrococci(13.6%), Streptococcus spp. (12.3%), E. coli (7.4%), Fungus & Yeast (1.6%) and others (5.8%). 3. Total numbers of bacteria were $9.2{\times}10^6$ to $1.21{\times}10^7/ml$(av. $1.805{\times} 10^7/ml$), numbers of coliform bacteria were $4.1{\times} 10^5$ to $9.4{\times} 10^5$/ml(av. $7.05{\times} 10^5$/ml) and somatic cell counts were $4.8{\times} 10^5$ to $1.52{\times} 10^6$ cells/ml (av. $9.5{\times} 10^5$cells/ml) in bulk milk. 4. As comparing with CMT score of +, ++ and +++, somatic cell counts were $3.4{\times} 10^5$ to $1.64{\times} 10^6$ cells/ml (av. $6.41{\times} 10^5$cells/ml), $5.4{\times} 10^5$ to $2.75{\times} 10^6$ cells/ml(av. $1.762{\times} 10^6$cells/ml) and $1.97{\times} 10^6$ to $9.75{\times} 10^6$ cells/ml(av. $7.781{\times} 10^6$cells/ml), respectively. 5. In investigation on dairy management, performance of dry cow therapy, teat dipping after milking, disinfection of milking machine at every milking, replacement of milk liner within 6months and opportunity of acquirement for the mastiris control techniques by dairy education were 65%, 40%, 45%, 55% and 50% in 20 dairy farms, respectively.