• Title/Summary/Keyword: extensional space

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The effects of drag reducing polymers on flow stability : Insights from the Taylor-Couette problem

  • Dutcher, Cari S.;Muller, Susan J.
    • Korea-Australia Rheology Journal
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    • v.21 no.4
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    • pp.213-223
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    • 2009
  • Taylor-Couette flow (i.e., flow between concentric, rotating cylinders) has long served as a paradigm for studies of hydrodynamic stability. For Newtonian fluids, the rich cascade of transitions from laminar, Couette flow to turbulent flow occurs through a set of well-characterized flow states (Taylor Vortex Flow, wavy Taylor vortices, modulated wavy vortices, etc.) that depend on the Reynolds numbers of both the inner and outer cylinders ($Re_i$ and $Re_o$). While extensive work has been done on (a) the effects of weak viscoelasticity on the first few transitions for $Re_o=0$ and (b) the effects of strong viscoelasticity in the limit of vanishing inertia ($Re_i$ and $Re_o$ both vanishing), the viscoelastic Taylor-Couette problem presents an enormous parameter space, much of which remains completely unexplored. Here we describe our recent experimental efforts to examine the effects of drag reducing polymers on the complete range of flow states observed in the Taylor-Couette problem. Of particular importance in the present work is 1) the rheological characterization of the test solutions via both shear and extensional (CaBER) rheometry, 2) the wide range of parameters examined, including $Re_i$, $Re_o$ and Elasticity number E1, and 3) the use of a consistent, conservative protocol for accessing flow states. We hope that by examining the stability changes for each flow state, we may gain insights into the importance of particular coherent structures in drag reduction, identify simple ways of screening new drag reducing additives, and improve our understanding of the mechanism of drag reduction.

A Study on the Transition of the Ddeulzip on Omi Village in Andong and Orock Village in Bonghwa (풍산김씨(豊山金氏)마을 뜰집의 변천과정(變遷過程)에 관한 연구(硏究) - 안동(安東) 오미(五美)마을과 봉화(奉化) 오록(梧麓)마을의 족보(族譜)를 바탕으로 -)

  • Kim, Hwa-Bong
    • Journal of architectural history
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    • v.13 no.3
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    • pp.51-67
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    • 2004
  • The purpose of this study is to bring light on the characteristics of the transition in the Ddeulzip. The subject of this study is clan village of Pungsan Kim's family in Andong Cultural Area. Architectural transition of Ddeulzip is analyzed into three part. The first part is settlement of family. In this process, there is a background and many types of settlement. The second part is the extension of family. The extensional types are 'near-by branch' and 'far-away branch'. The last part is variation of housing. Spacial requests of residence are changed endlessly. Thus the spacial types of Ddeulzip are changed by the construction time of building. In many case, we couldn't decide the building period. The genealogy of Chosun Dynasty is the base of family history. In this study, the construction activity of Ddeulzip is based on the genealogy. The phylogenetic tree of Ddeulzip in clan village is constructed by the genealogy. The figures of the type of bunch of grapes is made by phylogenetic tree based on the genealogy. Omi Village in Andong was settled at first in the 15C. The cause of settlement is the aim of escape from political oppression. For long time, Omi Village is developed gradually. There area is divided in some small family boundary. There spacial types are contained the characteristics of many times. Orock Village in Bonghwa is settled for search of best environment in the last of 17C. At that time, a lot of families of same clan are gathered in that village. For short time, Orock Village is enlarged quickly. Thus there spacial type is similar each other. But boundary of entire space of outdoor is constructed clearly by pavilion area, housing area and sanctuary area.

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A Study on the Evolution of the Holding and Utilizing System of Fisheries Resources in Korea (수산자원 소유.이용제도의 변천에 관한 연구)

  • 류정곤
    • The Journal of Fisheries Business Administration
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    • v.22 no.1
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    • pp.1-52
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    • 1991
  • This study deals with the evolutional history of the holding and utilization of fisheries resources in Korea. Fisheries resources have the basic characteristics of the density dependent self-regulating renewable and common property resources, Irrational utilization of fisheries resources is mainly due to the unlimited access to the resources. The holding and utilization of fisheries resources in Koryo era was opened to everyone. But it was nationalized in the early Yi Dynasty. The purpose of its nationalization was to provent the paticular powered-man with their monoplized holding and to levy fisheries tax. Eoeop-peop, the first modern fisheries law in Korea, was enacted as a part of the invasion policy of Japan in 1908. With the japanese annexation of Korea in 1910, the Japanese Government established a new institutional system of fisheries as a part of an overall reformation of the institutional for an implementation of the colonial policy. It was very the new enacted Fisheries Law (Gyogyorei). Also the Government enacted compulsorily another new Fisheries Law (Chosen Gyogyorei) with its adjunct laws and regulations revise the institutional system of fisheries on May 1, 1930. After Eoeop-peop enactment, the fisheries resources in Korea could be used only under the license, permission, and statement. After Korea was from Japan in 1945, Korea Government at last enacted the new fisheries law (Susaneop-peop) in 1953. The goal of Susaneop-peop was to achive the general usage and protection of the fisheries resources, and to attain the development and democratization of the fishery in Korea. This law was amended 13 times until 1990. The license fishery have a legal right on the fishery, called a fishery rigt. This right means a right of exclusive occupation and utilization of a unit of the inshore fishing grounds. The main evolutional issues of license fishery are as the following : 1) the foundation of the exclusive usable fishery right(1911, Gyogyorei), 2) the deletion of the settled U9space lift net and settled space sein net fishery, and the expansion of the cooperative fishery-No.1, 2, and 3 type cooperative fishery-(3rd amendment, 1963), 3) the deletion of the No.2 and 3 type cooperative fishery, and the separation of the culturing fishery in No.1 and 2 type culturing fishery (13th amendment, 1990). The effective period of the license fishery was amended as the following : 1) 1908(Eoeop-peop) : within 10 years, renovation system, 2) 1929(Chosen Gyogyorei) : within 10 years, unlimited extension system, 3) 1971. 7th amendment : 10 years, renovation system, 4) 1972. 8th amendment : 10 years, only 1 extension system, 5) 1975. 9th amendment : 5-10 years, only 1 extension system, 6) 1990.13th amendment : 10 years, within 10 years of total extensional years. The priority order of the fishery license was established in 1953 (Susaneop-peop). The amendment of it is as follows : 1) 1953. enactment \circled1 the fishing grounds that the fishery right is extablished 1st order : the existing fishery right man, unlimited renovation 2nd order : the corporate that the regional fisherfolk organized 3rd order : the rest experienced fishermen \circled2 new fishing grounds 1st order : the corporate that the regional fisherfolk organized 2nd order : the rest experienced fishermen 2) 1971. 9th amendment \circled1 the fishing grounds that the fishery right is established 1st order : the existing fishery right man, unlimited renovation 2nd order : the Eochongye that the regional fisherfolk organized 3rd order : the regional fishery cooperative that the regional fisherfolk organized 4th order : the rest experienced fishermen \circled2 new fishing grounds 1st order : the Eochongye that the regional fisherfolk organized 2nd order : the regional fishery cooperative that the regional fisherfolk organized 3rd order : the rest experienced fishermen 3) 1981. 10th amendment \circled1 the inside of No.1 type cooperative fishing grounds 1st order : the Eochongye that the regional fisherfolk organized 2nd order : the regional fishery cooperative that the regional fisherfolk organized 3rd orer : the rest experienced fishermen 4) 1990. 13th amendment \circled1 No.1 type cultural fishery 1st order : the Eochongye that the regional fisherfolk organized 2nd order : the regional fishery cooperative that the regional fisherfolk organized 3rd order : the rest experienced fishermen \circled2 No.2 type cultural and settle fisher : general priority order The effective period of the permission fishery was amended 6 timed. First, it was within 5 years and renovation system (Eoeop-peop). Now it is 5 years and renovation system. The effective period of the statement fishery was amended 4 times. First, it was within 5 years, and then was amended within 3 years(Chonsen Gyogyorei). Now it is 5 years.

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A Case Study of Geometrical Fracture Model for Groundwater Well Placement, Eastern Munsan, Gyeonggido, Korea (지하수개발을 위한 단열모델 연구사례(경기도 문산 동쪽지역))

  • Choi Sung-Ja;Chwae Uee-Chan;Kim Se-Kon;Park Jun-Beom;Sung Ki-Sung;Sung Ik-Whan
    • Economic and Environmental Geology
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    • v.39 no.2 s.177
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    • pp.163-171
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    • 2006
  • This study is the case of groundwater development based on the geometrical fracture model of target area established only through geological fracture mapping technique. A fracture mapping of $9km^2$, eastern Munsan, has been conducted to determine geological and hydrological factors for new water well placement in the Gyeonggi gneiss complex. Geophysical exploration was not applicable because of small restricted area and dense underground utilities at the site. Form line mapping on the basis of foliation orientation and rock type revealed a synform of NS fold axis bearing to the south. An EW geological cross-section passed through the site area shows a F2 synform as a double-wall ice cream spoon shape. Three regional faults of $N20^{\circ}E,\;N30^{\circ}W$, and NS have been dragged into the site to help understand extensional fault paths. The $N20^{\circ}E$ fault with dextral sense is geometrically interpreted as a western fault of two flexural conjugate type-P shear faults in the F2 synformal fold. The NE cross-section reveals that a possible groundwater belt in the western limb of super-posed fold area is formed as a trigonal prism within 100 m depth of the intersectional space between the $N20^{\circ}E$ fault plane and the weakly sheared plane of transposed foliation. Another possible fault for water resource strikes $N40^{\circ}E$. Recommended sites for new water well placement are along the $N20^{\circ}E\;and\;N40^{\circ}E$ faults. As a result of fracture mapping, 145 ton/day of water can be produced at one well along the $N20^{\circ}E$ fault line. Exploration of groundwater in the area is succeeded only using with geological fracture mapping and interpretation of geological cross-section, without any geophysical survey. Intersection of fault generated with the F2 synformal fold and foliation supply space of groundwater reserver.