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CFD분석을 통한 기류식 분쇄기 날개부의 최적설계 (Optimum Design for an Air Current Pulverizing Blade Using the Computational Fluid Dynamics)

  • 김건회;김한빛
    • 한국기계가공학회지
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    • 제19권8호
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    • pp.8-14
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    • 2020
  • In the air current pulverizing type grinding method, the blade wings fitted inside a casing are rotated at a high speed to generate a cornering air current, which facilitates the collision of materials with one another, leading to the pulverizing phenomenon. In contrast to mechanical grinding, grit pulverizing leads to fine grinding and less acid waste and degeneration of the material. Moreover, this approach prevents the loss of nutritional value, while allowing the milling grain to have an excellent texture. However, the existing air current pulverizing type machines consist of prefabricated blades, which cannot be rotated at a speed higher than 5,000 rpm. Consequently, the grinding process becomes time consuming with a low productivity. To overcome these problems, in this study, the shape and structure of the air current pulverizing type wings were optimized to allow rapid grinding at more than 8,000 rpm. Moreover, the optimal design for the ripening parts for the air current pulverizing type device was determined by performing a computational fluid dynamics analysis based on airflow analyses to produce machinery that can grinding materials to the order of micrometers.

Holocene Variations of Organic Carbon Contents in Lake Langer of King George Island, South Shetland Islands, West Antarctica

  • Khim, Boo-Keun;Yoon, Ho-Il;Kang, Cheon-Yun;Zhao, Junlin
    • Ocean and Polar Research
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    • 제26권3호
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    • pp.507-514
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    • 2004
  • A sediment core drilled from Lake langer on King George Island was analyzed for a variety of textural md geochemical properties along with $^{14}C$ age dates. These data were combined with published records of other cores to provide a detailed history of Holocene variation of total organic carbon (TOC) contents with respect to terrestrial paleoclimate change. The lithologic contrast of the lower diamicton and upper fine-grained sediments shows the glacier activity and subsequent lake formation. Low TOC contents fluctuated during the diamicton deposition whereas the increase of TOC began with the lake formation during the postglacial period that started about 5,000 yr B.p More notable are the distinct TOC peaks that may imply enhanced primary productivity during the warm period. The uniform and low TOC contents may reflect the limited productivity during the evolution of the lake. However, the recent TOC readvance clearly indicates gradual warming on King George Island. However, the paleoclimatic signature in the terrestrial lake environment during the Holocene seems to be subtle and less distinct, compared to the marine environment.

개에서 늑골 연골육종에 대한 영상학적 진단증례 (A Case Report: Diagnostic Imaging of a Chondrosarcoma of the Rib in a Dog)

  • 정유철;임창윤;오선경;정주현;이창우;윤정희;최민철
    • 한국임상수의학회지
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    • 제22권4호
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    • pp.444-449
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    • 2005
  • An 11-year-old female, Golden retriever dog with a history of solid mass on the chest wall was referred to Veterinary Medical Teaching Hospital, Seoul National University. The mass was firm on palpation. A soft tissue opacity mass with calcified foci around the right 7th rib and extrapleural patterns around the right 5th rib and 7th rib was shown on thoracic radiographs. The mass of the 7th rib has a mixed-echo pattern with a strong acoustic shadowing and internal vascular signals on ultrasonography. On CT scan, the mass showed contrast enhancement effect, expansive pattern of intrathoracic and extrathoracic legion around costochondral junction. The 7th rib appeared mildly lytic. The mass of the 5th rib had a soft tissue swelling without bone lysis. The mass was diagnosed as a sarcoma by fine needle biopsy. Therefore, the mass was surgically removed. Subsequent histopathological study found the mass was chondrosarcoma.

Stearic acid 유기박막의 표면주고 Image (Surface Structure Image of Stearic acid Organic Thin Films)

  • 장헌;송진원;최영일;이경섭
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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    • pp.562-564
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    • 2001
  • Transformation of molecular film occurs only usually in air-water interface, 2 dimensions domain's growth and crash are achieved. Organic matter thin film that accumulate molecular film in archaism board only that consist of growth of domain can understand correct special quality of accumulation film supplying information about fine structure and properties of matter of device observing information and so on that is surface forward player and optic enemy using AFM one of SPM application by nano electronics. The stable images are probably due to a strong interaction between the monolayer film and glass substrate. We are unable to obtain molecule resolution in images of the films but did see a marked contrast between images of the bare substrate and those with the network structure film deposited onto it. Formation that prevent when gas phase state and liquid phase state measure but Could know organic matter that molecules form equal and stable film when molecules were not distributed evenly. and accumulated in solid state only.

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LB박막의 이미지와 표면구조분석에 관한 연구 (A Study on the Image and Surface Structure analysisthat Manufacture by LB Method of LB Thin Film)

  • 송진원;이경섭;최영일;정헌상;구할본;김영근;이영길
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 하계학술대회 논문집 C
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    • pp.1618-1620
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    • 2002
  • Transformation of molecular film occurs only usually in air-water interface, 2 dimensions domain's growth and crash are achieved. Organic matter thin film that accumulate molecular film in archaism board only that consist of growth of domain can understand correct special quality of accumulation film supplying information about fine structure and properties of matter of device observing information and so on that is surface forward player and optic enemy using AFM one of SPM application by nano electronics. The stable images are probably due to a strong interaction between the monolayer film and glass substrate. We are unable to obtain molecule resolution in images of the films but did see a marked contrast between images of the bare substrate and those with the network structure film deposited onto it. Formation that prevent when gas phase state and liquid phase state measure but Could know organic matter that molecules form equal and stable film when molecules were not distributed evenly, and accumulated in solid state only.

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Speaker-specific Implementation of VOT Values in Korean

  • Han, Jeong-Im;Kim, Joo-Yeon
    • 음성과학
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    • 제15권4호
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    • pp.7-18
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    • 2008
  • The purpose of the present study is to test whether VOT values of the Korean plain stops in intervocalic position are encoded differently by individual speakers. In Scobbie (2006), the VOT values to the /p/-/b/ voicing contrast in Shetland Isles English were found to demonstrate a high degree of inter-speaker variation. More importantly such variation was not arbitrary: first, there was an inverse relationship between the amount of prevoicing for /b/ and the duration of aspiration for /p/. Second, the inter-speaker variation was shown to be similar between the subjects and their parents. These results suggest that the phonetic targets for VOT are specified in fine detail by speakers. The present study further explores this issue in terms of testing 1) whether the likelihood and the amount of voicing for the intervocalic plain stops in Korean show inter-speaker variation; 2) whether the likelihood and the exact amount of voicing for the intervocalic plain stops in Korean are closely related to the amount of aspiration for the Korean intervocalic aspirated stops. The results of the study suggest that the voicing of intervocalic plain stops in Korean varied according to the individual speakers, but it did not seem to be directly interrelated with the amount of aspiration of the aspirated stop sin the same phonological position.

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서울시 미세먼지 농도의 지역적 특성파악을 위한 연구 - 구별 분포 특성 및 차량등록대수와의 관계 - (Understanding on Regional Characteristics of Particular Matter in Seoul - Distribution of Concentration in Borough Spatial Area and Relation with the Number of Registered Vehicles -)

  • 박종길;최윤정;정우식
    • 한국환경과학회지
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    • 제26권1호
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    • pp.55-65
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    • 2017
  • Average concentration of PM in Seoul metropolitan area satisfied the Korean air quality standard in 2010. Furthermore, concentration of PM in all boroughs across Seoul met the air environment standard in 2012. $PM_{10}$ concentration was relatively higher in center of Seoul in comparison to the rest, while $PM_{2.5}$ concentration showed exactly the contrary result. We analyzed the effect that PM emissions from vehicles would have on PM concentrations across Seoul. The results showed that average annual PM concentration recently decreased in Seoul although the number of vehicles registered annually continued its upward trend. By contrast, average fine dust concentrations in Seoul showed a decline which suggested that correlation between annual average PM concentrations and number of registered vehicles remained low. However, year-on-year vehicle registration rate recently showed a declining tendency in the same way as the trend of changes in average PM concentrations. Particularly, the upward trend in annual average PM concentrations in 2002 and 2007 was consistent with the increase in vehicle registration rate, suggesting that vehicle registration rate was closely associated with changes in PM concentrations.

메뚜기 (Euprepocnemis shirakii) 성충의 혈구유형 (Hemocyte Types in Adult Grasshpper, Euprepocnemis shirakii Bolivar)

  • 장병수;한성식;여성문
    • Applied Microscopy
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    • 제24권2호
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    • pp.93-104
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    • 1994
  • Six types of hemocytes were identified in adult grasshopper, Euprepocnemis shirakii Bolivar. The morphological and ultrastructural characteristics of these cells were characterized by phase contrast, scanning and transmission electron microscope. The prohemocytes are small and spherical cells with large nucleus. The plasmatocytes are spindle shaped or polymorphic cells which show numerous cytoplasmic processes on the cell surface and they have lysosomes and vesicles that may be involved in phagocytic function. Especially, multivesicular bodies are observed in the polymorphic cells. The granulocytes I are spherical shaped cells. They are characterized by a number of electron dense granules measuring $0.2-0.3{\mu}m$ in average diameter and marginal band of microtubules which are always in close proximity to the cell membrane. The granulocytes II are oval or spindle-shaped cells. They contain large electron dense granules measuring $0.5-0.8{\mu}m$ in average diameter. Their cytoplasm is filled with numerous granules. The spherulocytes contain large amounts of spherules that most of their cytoplasm. Spherules filled with fine granules or flocculent materials. The oenocytoids are large spherical cells with few cytoplasmic organelles. Their cytoplasm contains peculiar aspect of motochondria and numerous polyrobosome.

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최근발간된 한국 어린이 잡지의 분석 (A Survey on Children's Magazines in Korea)

  • 김효정
    • 한국문헌정보학회지
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    • 제3권
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    • pp.103-123
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    • 1973
  • The magazine in mordern society is a powerful mass-media. Children are generally interested in magazines, which are relatively in expensive, readily and reguarly, and easy to read. The research chose 5 children's magazines published in Korea in 1973 for close analysis. The Sonyon (Youth) was found to be closer to a pure literary reading for children; the Sae Sonyon (New youth) and Sonyonsegeh (World of the youth) were purposes oriented toward popular amusement purposes carrying a great number of catoons; the Sonyon Chungang (Chungang youth) carried too many advertisements; and the Okae Dong Mu (Rear group) was rather weak in contents in fine contrast with its colourful appearance. The following characteristics were generalized from analysis of the five children's magazines published in Korea: (1) The function of periodic information dissemination was very weak, feared in danger of being wiped out. : (2) The educative and guidance function was found rather weak. (3) Economic motives seemed stronger in spite of the expressed zeal for missions of magazine. (4) In terms of contents variety was lackey, with little individuality for each magazine. (5) Generally emphasis was given to pictoral contents rather than to reading articles.

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A New Connected Coherence Tree Algorithm For Image Segmentation

  • Zhou, Jingbo;Gao, Shangbing;Jin, Zhong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제6권4호
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    • pp.1188-1202
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    • 2012
  • In this paper, we propose a new multi-scale connected coherence tree algorithm (MCCTA) by improving the connected coherence tree algorithm (CCTA). In contrast to many multi-scale image processing algorithms, MCCTA works on multiple scales space of an image and can adaptively change the parameters to capture the coarse and fine level details. Furthermore, we design a Multi-scale Connected Coherence Tree algorithm plus Spectral graph partitioning (MCCTSGP) by combining MCCTA and Spectral graph partitioning in to a new framework. Specifically, the graph nodes are the regions produced by CCTA and the image pixels, and the weights are the affinities between nodes. Then we run a spectral graph partitioning algorithm to partition on the graph which can consider the information both from pixels and regions to improve the quality of segments for providing image segmentation. The experimental results on Berkeley image database demonstrate the accuracy of our algorithm as compared to existing popular methods.