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Flow Resistance of Plane Nettings for Net Cages (우리 그물용 평면 그물감의 유수저항)

  • KIM Tae-Ho;KIM Dae-An;RYU Cheong-Ro
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.34 no.3
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    • pp.254-259
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    • 2001
  • In order to make clear the resistance of plane nettings u,sed widely in constructing net cages, the resistance R taken by $R=kSU^2$, where S was the wall area of nettings, U the flow velocity, and k the resistance coefficient, was measured in a circulating water channel by using nylon Raschel nettings and PE trawler-knotted nettings coated with anti-fouling paint or not and then the properties of coefficient k were investigated. The mesh size L and the angle $\phi$ between two adjacent bars was given by the function of Reynolds number ${\lambda}U/v$ in the region of ${\lambda}U/v<180$, i. e., $$k=350(\frac{\lambda U}{v})^{-0.25}$$.where $\lambda$ was the representative size of nettings expressed as $$\lambda=\frac{{\pi}d^2}{2L\;sin\;2{\phi}}$$On the other hand, the coefficient k was almost fixed between 92 and 102 ($kg{\cdot}s^2/m^4$) in the region of ${\lambda}U/v{\geq}180$ and varied according to the ratio $S_n/S$ of the total area $S_n$ of nettings projected to the plane perpendicular to the water flow to the wall area S of nettings, i.e., it was given by $$k=98.6(\frac{S_n}{S})^{1.19}$$ regardless of the coating of paint.

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Influence of shading and polyethylen vinyl mulching on growth and yield of Cinidium officinale Makino (차광(遮光), 비닐피복(被覆)이 궁궁이(천궁(川芎))의 생육(生育) 및 수량(收量)에 미치는 영향(影響))

  • Hwang, Hyung-Baek;Kim, Jae-Chul;Choi, Jang-Soo;Choi, Boo-Sull
    • Korean Journal of Medicinal Crop Science
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    • v.3 no.2
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    • pp.156-164
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    • 1995
  • The study was carried out to elucidate the influenced of shading and mulching with polyethylen vinyl on growth and yield of Cinidium officinale Makino, and improve the cultivation method of those medicinal plants in northern area of Gyeong-buk province, Korea. Top fresh weight of Cinidium officinale Makino was increased by both 35 % and 55% shading compared to the non-shadingand decreased by 75 % shading, but that of Ligusticum chuanxing Hart. Was decreased by the shading tested The summer wilt of Cinidium officinale Makino severely occurred in non-shading but greatly reduced by 55 % or 75 %shading, while no difference was observed in Ligusticum chuanxing Hort, between the shading and the non-shading. Dry root yield Cinidium officinale Makino was increased by 17 % and 19 % in 35 % and 55 % shading levels, respectively, compared to the dry root yield(254kg/10a) in non-shading. However, it was decreased in Ligusticum chuaxing Hort. by the shading. Emergence ratio of Cinidium officinale Makino was increased by black polyethylen vinyl mulch but decreased by transparent polyethylen vinyl mulch, compard to non-mulch. Polyethylen vinyl mulch increa­sed the top fresh weight of Cinidium officinale Makino Especialy black polythylen vinyl mulch was very effective on increasing the top fresh weight. Dry root yield of Cinidium officinale Makino was increased by 32 % and 30 %, respectively, compared to the non-shading.

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STUDIES ON THE TISSUE CULTURE OF PANAX GINSENG

  • Harn C
    • Proceedings of the Ginseng society Conference
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    • 1974.09a
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    • pp.9-22
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    • 1974
  • Unlike the tissue culture in animals and human being, in higher plants various parts of the plant are cultured for varied purposes, and they are named variously depending on which parts are used as explants or what purposes they are cultured for. Followings are some of the names of culture used frequently: organ culture, tissue culture, callus culture, single cell culture, meristem culture, mericlone culture, ovary culture, ovule culture, embryo culture, endosperm culture, anther culture, pollen culture, protoplast culture, etc.. As the names of the culture indicate, in some kinds of culture the explants used for culture are actually not tissues, but organs, single cells, or protoplasts. It seems, however, convenient to call all of the above-mentioned cultures grossly as tissue culture. Several kinds of tissue culture were attempted using Panax ginseng as material and some of the results were summarized below. 1. Callus culture After dormancy of the sed was broken, whole embryo or parts (hypocotyl, cotyledon and epicotyl) of partly grown embryo were cultured in the media supplemented with growth regulators. Rapid swelling occurred in a few weeks, but most of the swelling was observed only in the basal part of epicotyl, changes in the other parts of embryo appearing in much later stages. The swelling or increase in size, however, was resulted not from the divisions of cells, but from the mere expansion of cell. Real calli were formed about two months after inoculation of explants. Callus tissues developed from cortex, pith, and vascular bundle in the cases of hypo- and epicotyl, from mesophyl tissue in the case of cotyledon. Shoots developed more easily from cotyledons regardless of whether they are detached from or attached to the embryo proper. 2. Culture in the Knudson C medium When cotyledons, detached from or attached to the embryo proper, were cultured in the growth regulator-free Knudson C medium comprision only several kinds of mineral compounds and sucrose, shoot primordium or callus developed profusely and finally plantlets were produced directly from shoot primordium or indirectly through callus. In this medium epidermal cells as well as mesophyl cells of the cotyledon became meristematic and divided, changing into multinucleate cells or multicellular bodies, developing eventually into either shoot primordia or calli. 3. Anther culture Anthers were cultured in the media supplemented with various growth regulators applied singly or in combinations. Callus was formed mostly in the connective tissue of anther. Cells of anther wall layers changed in appearance, but no division occurred. Microspores of all stages in development were not changed, ruling out the possibility that microspore-originated callus might be formed. 4. Isolation of protoplast Protoplasts were isolated from young root, leaf, and epicotyl, using 0.7M D-mannitols as osmoticum and using macerozyme and cellulase respectively for maceration and digestion of the cell wall. Production in large number of naked intact protoplast was rather difficult as compared with other plant species. Fusion of protoplasts occurred infrequently mainly due to the fewer number of naked protoplasts in the solution.

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Associated-Genes and Virulence Factors of Staphylococcus aureus Isolated from Nasal Cavity of Neonates (신생아 비강에서 분리된 황색포도구균의 병원성 인자와 관련 유전자)

  • Kim, Yung Bu;Moon, Ji Young;Park, Jae Hong
    • Clinical and Experimental Pediatrics
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    • v.46 no.1
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    • pp.24-32
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    • 2003
  • Purpose : Nosocomial infection with Staphylococcus aureus, especially methicillin resistant S. aureus, has become a serious concern in the neonatal intensive care unit. The aim of this study is to investigate the virulence factors, and the relationship between the antibiotic resistance and the associated genes of Staphylococcus aureus isolated from nasal cavity of neonates. Methods : Fifty one isolates of S. aureus were obtained from nasal swab taken in 28 neonates in the NICU and nursery of Pusan National University Hospital between February and May, 2001. They were tested in regard to antibiotic susceptibility, coagulase test and typing, plasmid DNA profile, as well as reactivity to enterotoxin A-E(sea, seb, sec, sed, see) genes and toxic shock syndrome toxin-1(tst) gene by polymerase chain reaction(PCR). Associated genes such as mecA, mecR1, mecI, and femA were also determined by PCR. The origin of MRSA strains was assessed using DNA fingerprinting by arbitrarily-primed polymerase chain reaction(AP-PCR). Results : Twenty three(45.1%) and six(11.8%) isolates were resistant to oxacillin and vancomycin respectively. Multidrug resistance to three or more of the antibiotics tested was observed in 51.0% of the isolates. Forty two isolates were coagulase positive and twenty two isolates had mecA gene. Sixteen isolates had both mecA and femA genes and had type I-III plasmids. 64.7% of isolates carried sec gene, and 80.4% carried tst gene. DNA fingerprinting by AP-PCR for 12 MRSA strains showed 10 distinct patterns, suggesting different origins. Conclusion : We confirmed that the prevalence of nasal carriage of S. aureus and the incidence of antimicrobial-resistant S. aureus, especially vancomycin resistance, is very high in neonates who were admitted in NICU and nursery. It is possible that these pathogens are responsible for serious nosocomial infections in neonates. The need for improved surveillance and continuous control of pathogens is emphasized.