• 제목/요약/키워드: H-section

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새로운 날개단면을 이용한 프로펠러 설계법 - 콘테이너선에 응용 - (A Propeller Design Method with a New Blade Section : Applied to Container Ships)

  • 이진태;김문찬;안종우;반석호;김호충
    • 대한조선학회논문집
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    • 제28권2호
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    • pp.40-51
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    • 1991
  • 캐비테이션 특성이 우수하고 추진효율이 높은 콘테이너선용 프로펠러를 설계하기 위하여 새로운 날개단면(KH18)을 이용한 프로펠러 설계법을 제안하였다. KH18 단면은 캐비테이션 초생곡선(Cavitation-free bucket diagram) 및 양력-항력곡선(Lift-drag curve)에서 폭이 넓어 불균일한 선미후류에서 작동되는 선박용 프로펠러의 날개 단면으로 적당하리라 판단되었다. 새로운 날개 단면을 이용한 콘테이너선의 프로펠러 설계를 위하여 양력면이론을 사용하였다. 프로펠러 설계시 코오드 방향 부하분포를 설계변수로 선택하여 5개의 프로펠러를 설계하였고, 단면 변화의 영향을 비교하기 위하여 NACA형 단면을 갖는 프로펠를 설계하여 예인수조 및 캐비테이션 터널에서 모형시험을 수행하였다. 모형시험 결과 코오드 방향 부하분포가 프로펠러 반경의 70% 내부에서는 날개 앞날의 부하가 적고 그 외부에서는 날개 앞날부하가 상대적으로 큰 코오드방향 부하분포를 갖는 프로펠러(KP197)가 NACA 단면을 갖는 프로펠러에 비하여 추진효율은 1% 향상되었고 캐비테이션 발생양은 30% 감소하였으며 선체변동압력은 9%감소하였다. 새로운 날개단면을 갖는 프로펠러의 캐비테이션 특성이 우수함을 고려하여 낱개 전개면적비를 감소시킨다면 더 많은 추진효율 증가를 기대할 수 있으리라 판단된다.

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Cyanobacterial Diversity Shifts Induced by Butachlor in Selected Indian Rice Fields in Eastern Uttar Pradesh and Western Bihar Analyzed with PCR and DGGE

  • Kumari, Nidhi;Narayan, Om Prakash;Rai, Lal Chand
    • Journal of Microbiology and Biotechnology
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    • 제22권1호
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    • pp.1-12
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    • 2012
  • The present study examines the effects of 30 mg/kg butachlor on the cyanobacterial diversity of rice fields in Eastern Uttar Pradesh and Western Bihar in India. A total of 40 samples were grouped into three classes [(i) acidic, (ii) neutral, and (iii) alkaline soils], based on physicochemical and principle component analyses. Acidic soils mainly harbored Westillopsis, Trichormus, Anabaenopsis, and unicellular cyanobacteria; whereas Nostoc, Anabaena, Calothrix, Tolypothrix, and Aulosira were found in neutral and alkaline soils. Molecular characterization using 16S rRNA PCR and DGGE revealed the presence of 13 different phylotypes of cyanobacteria in these samples. Butachlor treatment of the soil samples led to the disappearance of 5 and the emergence of 2 additional phylotypes. A total of 40 DGGE bands showed significant reproducible changes upon treatment with butachlor. Phylogenetic analyses divided the phylotypes into five major clusters exhibiting interesting links with soil pH. Aulosira, Anabaena, Trichormus, and Anabaenopsis were sensitive to butachlor treatment, whereas uncultured cyanobacteria, a chroococcalean member, Westillopsis, Nostoc, Calothrix, Tolypothrix, Rivularia, Gloeotrichia, Fischerella, Leptolyngbya, and Cylindrospermum, appeared to be tolerant against butachlor at their native soil pH. Butachlor-induced inhibition of nitrogen fixation was found to be 65% (maximum) and 33% (minimum) in the soil samples of pH 9.23 and 5.20, respectively. In conclusion, low butachlor doses may prove beneficial in paddy fields having a neutral to alkaline soil pH.

Explicit matrix elements for Raman scattering blueward of H gamma

  • 이희원
    • 천문학회보
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    • 제35권1호
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    • pp.50.2-50.2
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    • 2010
  • We present the explicit expressions for the matrix elements associated with the interaction of photons with atomic hydrogen. These expressions are applied to compute the scattering cross section for the Raman scattering operating blueward of Lyman epsilon and H gamma. A brief discussion that re relevant to some symbiotic stars and young planetary nebulae is also presented.

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UREA-MOLASSES AND COTTONSEED-MOLASSES SUPPLEMENTS FOR DAIRY GOATS

  • Sarwiyono, Sarwiyono;Mcllroy, B.K.M.H.;Dixon, R.M.;Holme, J.H.G.
    • Asian-Australasian Journal of Animal Sciences
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    • 제5권4호
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    • pp.653-658
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    • 1992
  • Crossbred dairy does were fed a roughage diet (IVOMD 56%, N 2.27%) ad libitum, and supplemented with urea-molasses (3% W : W) (UM) at levels on an air dry basis of 1.5% or 3% of liveweight or an iso-energetic, iso-nitrogenous mixture of cottonseed meal and molasses (25 : 75 w : w) (CM). Eight does, four lower-producers and four higher-producers (1.9 and 2.5 kg/day respectively in week 7 of lactation) arranged in two Latin Squares, received each of the four diets for three weeks. Dry matter, digestible organic matter and N intakes were higher for high-producers and high levels of supplement but did not differ between nitrogen sources. Milk production was higher by high-producers; interactions were significant between level of supplement and production group and between level of supplement and N-source, with maximum production by high producers on high levels of CM. The main effects of level of supplement were only significant for production or composition. and total solids; N-source did not have significant effects on liveweight, milk production or composition. We conclude that does of moderate capacity for milk production, receiving a diet of two-thirds moderate quality roughage, one third urea-molasses, will not respond to increased level of supplementation or to replacement of urea with cottonseed meal.

중국 성인여성(中國 成人女性)의 ISO에 따른 의류치수규격 연구(衣類値數規格 硏究) (A Study on the Apparel Sizing System of ISO for Chinese Adult Women)

  • 손희순;위혜정;김은희;강연경
    • 패션비즈니스
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    • 제10권1호
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    • pp.58-78
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    • 2006
  • This study materializes body type measurement based on ISO(International Standard Organization)size system, targeting 1381 Chinese women, and suggests clothes size standards. It provides basic information on Chinese women size for Korean clothes companies advanced in China to strengthen the national competitiveness of Korean clothing industry. First, after the body type examination, based on the ISO's drop value, the results of types are in its decreasing order: A, M, H, and D. Second, women upper garment sizes by body types are set in the section of height 152cm, 160cm, and 168cm. Garment sizes are suggested based on the section that has more than 0.8% of appearance rate for the survey target: A, H, and M. Third, the clothes sizes of women pants are set in the section of height 152cm, 160cm, and 168cm just with the same as the upper garment.