• Asian-Australasian Journal of Animal Sciences
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• 제33권11호
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• pp.1858-1865
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• 2020

Objective: The microbiota of dairy cow milk varies with the season, and this accounts in part for the seasonal variation in mastitis-causing bacteria and milk spoilage. The microbiota of the cowshed may be the most important factor because the teats of a dairy cow contact bedding material when the cow is resting. The objectives of the present study were to determine whether the microbiota of the milk and the cowshed vary between seasons, and to elucidate the relationship between the microbiota. Methods: We used 16S rRNA gene amplicon sequencing to investigate the microbiota of milk, feces, bedding, and airborne dust collected at a dairy farm during summer and winter. Results: The seasonal differences in the milk yield and milk composition were marginal. The fecal microbiota was stable across the two seasons. Many bacterial taxa of the bedding and airborne dust microbiota exhibited distinctive seasonal variation. In the milk microbiota, the abundances of Staphylococcaceae, Bacillaceae, Streptococcaceae, Microbacteriaceae, and Micrococcaceae were affected by the seasons; however, only Micrococcaceae had the same seasonal variation pattern as the bedding and airborne dust microbiota. Nevertheless, canonical analysis of principle coordinates revealed a distinctive group comprising the milk, bedding, and airborne dust microbiota. Conclusion: Although the milk microbiota is related to the bedding and airborne dust microbiota, the relationship may not account for the seasonal variation in the milk microbiota. Some major bacterial families stably found in the bedding and airborne dust microbiota, e.g., Staphylococcaceae, Moraxellaceae, Ruminococcaceae, and Bacteroidaceae, may have greater influences than those that varied between seasons.

• Tribology and Lubricants
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• 제25권2호
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• pp.120-124
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• 2009

In automobile chassis system, several environmental factors weaken durability of automobile's components. The environmental factors are temperature, humidity, intensity of radiation and dust particle inflow. Especially, dust particle inflow leads to increase in friction and wear of automobile's components. The wear of automobile's component leads to increase in noise and exerts a bad influence on life of components. In this study, dust particles were investigated for study on the influence of dust particle inflow. Dust particles are collected on urban area, rural area and highway in China. The size of dust particle is analyzed using the image plus program, and the element of dust particle is analyzed using the SEM and EDX. The elements of dust particle are $SiO_2$ and $Al_{2}O_{3}$. The other elements(Na, Ca, Cl etc..) are detected on urban area and highway.

• 한국환경보건학회지
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• 제43권6호
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• pp.491-498
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• 2017

Objective: Bacterial abundance and community compositions have been examined in Asian dust events, clarifying their impacts on public health. This study aims to determine the bacterial community compositions and viable bacteria in Asian dust particles in the Asian dust or non-Asian dust event of March 2016. Methods: The dust samples were collected using the high volume air sampler or high volume cascade impactor, and bacterial 16S rRNA genes were amplified using PCR, followed by pyrosequencing. Bacterial diversity index, richness estimate and community composition in the particles were analyzed from the sequencing data using Mothur software. Results: The results showed that the diversity and richness during Asian dust events were higher than them in non-Asian dust events. The total bacterial community analysis showed that at the phylum Proteobacteria, Actinobacteria and Firmicutes were the most dominant of Asian dust events and non-Asian dust events. In addition, the bacterial colony counts were higher during Asian dust event, comparing with non-Asian dust event. Conclusions: This study showed that bacterial community and richness of Asian dust samples was more complex and higher than non-Asian dust samples in Gyeonggi-do, Korea, which could affect public health and environment. Thus, the continuous monitoring of Asian dust could be an alternative for managing airborne bacteria.

• 한국산학기술학회논문지
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• 제21권11호
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• pp.219-225
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• 2020

본 연구는 요구되는 전압효율이 83% 이상인 풍량 10,000 ㎥/min급의 장수명 송풍기를 개발하기 위하여 송풍기를 설계·제작하여 송풍기 성능시험과 침식 실험을 통하여 개발품에 대한 성능을 확인하였다. Dust deflector의 영향을 살펴보기 위하여 각기 다른 길이의 Dust deflector를 갖는 5가지의 실험용 임펠러를 제작하여 침식 실험을 수행하였다. 가혹한 조건으로 실험을 수행하기 위하여 침식을 유발하는 분진 대체재로 1kg의 스틸 쇼트 볼(𝛷0.2 mm)을 사용하였다. 자체 제작한 폐루프 타입의 침식 실험 장치에서 160시간 동안 연속으로 가동 운전하여 실험하였다. Dust deflector에 의한 침식성능을 평가하기 위하여 마모두께를 측정하였다. 3차원 스캐너로 침식 실험 전 형상과 침식 실험 후 형상을 스캐닝하여 마모두께를 측정하였다. 모델 송풍기를 설계·제작하여 송풍기 성능을 시험한 결과, 모델 송풍기 측정값을 기준으로 개발 송풍기로의 환산 결과 전압 690.6 mmAq, 풍량 16,243.6 ㎥/min, 효율 83.6 %로 나타났다. 송풍기의 침식 실험 장치를 설계·제작하여 가혹한 조건으로 침식 실험을 수행하여 dust deflector가 부착된 송풍기인 개발 송풍기가 dust deflector가 없는 기존 송풍기에 비하여 임펠러 마모두께를 기준으로 190 % 이상의 개선 효과가 있는 것으로 나타났다.

• 한국환경교육학회지:환경교육
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• 제21권2호
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• pp.51-67
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• 2008

The purpose of this study is to develop and applicate the elementary environmental textbook in order to solve its problem and to improve attitude related to the Asian dust. The results in this research are as follows. First, it was showed that three groups who composed of teachers, parents and students in the elementary school had recognized the serosities and problems caused by the Asian dust form TV, and that such problems was associated with increase of the desertification and the global warming. Especially the student group insist that the cause in Asian dust is due to the natural phenomena or industrialization. Second, as a result in analysis on the Asian dust through both textbooks on the 7th elementary curriculum and subsidiary textbooks, contents concerning Asian dusts was little or noting. In addition, in the subjects of Science, Society and Health for the 5th and 6th grade students in the elementary school, they were explained partially as one of the air pollutants. Third, the elementary environmental textbook on the Asian dust was developed for the 5th and 6th grade students. The textbook is composed of four contents on the material which is harmful of the human health and life in Asian dust, the special news of Asian dust, and the best answer to solve Asian dust as well as the cause and the source of Asian dust. Forth, as a result in classes using the environmental textbook developed by four themes about the Asian dust, its application is meaningful in the level of p value in the view of knowledge, awareness and attitude of the experiment group. They was more improved in 37%, 14%, and 15%, respectively, than the comparative group. In conclusion, the environmental textbook related to Asian dust will play an important role in useful tool to understand the right knowledge, awareness, and attitude which makes an effort on its effective management in the elementary school.

• 한국화재소방학회논문지
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• 제31권1호
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• pp.50-57
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• 2017

본 논문은 분진 및 풍속에 따른 연기감지기 챔버의 응답특성에 관한 연구이다. 연기감지기가 실내에 적용됨으로 인해 화재의 조기감지 측면에서는 나아졌으나, 실내에서 발생되는 다양한 생활먼지 및 환경적인 요건 등에 의해 발생될 수 있는 부작동 및 오작동에 대한 연구는 미비한 편이다. 이에 본 연구에서는 다양한 분진 및 풍속에 따른 연기감지기의 실내적응성을 연구하기 위해 연기챔버의 형태 및 구조가 다른 4종류의 광전식연기감지기를 실험대상으로 하고, 플라이애시, 활석가루 그리고 섬유분진(흑채가루)을 실험시료로 하여 분진시험을 진행하였다. 또한 연기챔버 내의 오염도에 따른 응답특성을 관찰하기 위해 추가적으로 분진시험 풍속을 0.25 m/s, 0.5 m/s, 1.0 m/s로 설정하여 인가하였다. 실험결과 플라이애시 및 활석가루, 섬유분진의 경우 분진시험 기준풍속조건인 0.25 m/s에서는 분진인가 후 작동시험 및 부작동시험에서 모두 적합한 것으로 나타났다. 반면, 가혹풍속조건인 0.5 m/s 및 1.0 m/s에서는 플라이애시 및 활석가루의 경우 부작동시험에서 비화재보인 오작동이 나타났고, 섬유분진의 경우 작동시험에서 정상적으로 작동되지 않아 부작동이 발생하는 것으로 확인되었다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3651-3656
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• 2012

The size-segregated atmospheric aerosols have been collected at 1100 m site of Mt. Halla in Jeju, a background area in Korea, using 8-stage cascade impact air sampler during Asian dust and non-Asian dust storm periods. Their ionic and elemental species were analyzed, in order to examine the pollution characteristics and composition change between Asian dust and non-Asian dust periods. The major ionic species such as nss-$SO_4{^{2-}}$, $NH_4{^+}$, and $K^+$ were predominantly distributed in the fine particles (below $2.1{\mu}m$ diameter), and besides the $NO_3{^-}$ was distributed more in coarse particle fraction than fine particle. On the other hand, the typical soil and marine species i.e., nss-$Ca^{2+}$, $Na^+$, $Cl^-$, and $Mg^{2+}$, were mostly existed in the coarse particles (over $2.1{\mu}m$ diameter). As well in the elemental analysis of aerosols, the major soil-originated Al, Fe, Ca, and others showed prominently high concentrations in the coarse particle fraction, whereas the anthropogenic S and Pb were relatively high in the fine particle fraction. From the comparison of aerosol compositions between Asian dust and non-Asian dust periods, the concentrations of the soil-originated species such as nss-$Ca^{2+}$, Al, Ca, Fe, Ti, Mn, Ba, Sr have increased as 2.7-4.2 times during the Asian dust periods. Meanwhile the concentrations of nss-$SO_4{^{2-}}$ and $NO_3{^-}$ have increased as 1.4 and 2.0 times, and on the contrary $NH_4{^+}$ concentrations have a little bit decreased during the Asian dust periods. Especially the concentrations of both soil-originated ionic and elemental species increased noticeably in the coarse particle mode during the dust storm periods.

• International Journal of Safety
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• 제1권1호
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• pp.47-51
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• 2002

This study was performed by measuring the minimum ignition temperature of polyurethane form recovered from the recycling process of the end-of-life home appliances. The critical ignition temperature of polyurethane form was lower as the size of the sample vessel was increased, and that of polyurethane form using cyclopentane as the forming agent was relatively lower than the polyurethane form using CFC and the combustion of cyclopentane-polyurethane form occurred fiercely. It is considered that the recycling process of end-of-life home appliances using cyclopentane-polyurethane form as the insulator would require a special fire and dust explosion prevention measures since there exists a high potential hazard of fire and dust explosion during crushing and storage processes.

• Tribology and Lubricants
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• 제25권4호
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• pp.261-264
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• 2009

Environmental factors affect parts of the automobile. When dust particles are embedded, specially, friction and wear of the rubber-seal in automobile chassis system are increased. Increase in friction and wear leads to weakness of component and reduction of mechanical life. In this study, the wear characteristics of rubber-seal for inflow of dust particles are investigated. Silica($SiO_2$) and alumina($Al_2O_3$) particles are used as a dust particle because these particles are main elements of dust particles. The sliding wear tester are used for investigate the wear characteristics of rubber-seal. If the single dust particle($SiO_2$) is embedded in the rubber-seal component, the influence of dust particle size is more than that of inflow rate on the wear characteristics of rubber-seal. If the mixed dust particles are embedded in the rubber-seal component, the wear rate is increased as the rate of alumina that has a bigger hardness is increased. If the mixed dust particles that have different hardness are embedded in the rubber-seal component, the influence of particle size is more than that of particle hardness.

• Asian-Australasian Journal of Animal Sciences
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• 제33권6호
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• pp.1042-1055
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• 2020

Objective: The ecosystem of an animal farm is composed of various elements, such as animals, farmers, plants, feed, soil, and microorganisms. A domesticated animal's health is largely connected with the reservoir of bacteria and viruses in animal farms. Although a few studies have focused on exploring the gut microbiome of animals, communities of microbiota and viruses in feedlots have not been thoroughly investigated. Methods: Here, we collected feces and dust samples (4 groups: cattle feces, C_F; horse feces, H_F; cattle dust, C_D; and horse dust, H_D) from cattle and horse farms sharing the same housing and investigated their microbiome/virome communities by Illumina sequencing. Results: Dust groups (C_D and H_D) showed higher microbial diversity than feces groups (C_F and H_F) regardless of animal species. From the microbial community analysis, all the samples from the four groups have major phyla such as Proteobacteria (min 37.1% to max 42.8%), Firmicutes (19.1% to 24.9%), Bacteroidetes (10.6% to 22.1%), and Actinobacteria (6.1% to 20.5%). The abundance of Streptococcus, which commonly recognized as equine pathogens, was significantly higher in the horse group (H_D and H_F). Over 99% among the classified virome reads were classified as Caudovirales, a group of tailed bacteriophages, in all four groups. Foot-and-mouth disease virus and equine adenovirus, which cause deadly diseases in cattle and horse, respectively, were not detected. Conclusion: Our results will provide baseline information to understand different gut and environmental microbial ecology between two livestock species.