• Title/Summary/Keyword: 상류층

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Study on the operation of water intake station in tidal affected river (감조하천 구간에서의 취수장 운영방안 연구)

  • Oh, ChangYeol;Son, KyungHwan;Lee, JunHo;Won, YooSeung
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.235-235
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    • 2019
  • 감조하천 구간에서의 수면경사 및 유속분포 등 흐름특성은 조석의 영향으로 자연하천과 달리 매우 복잡하고 다양한 형태를 보이고 있다. 또한 하류에서 상류로 조류 유입시 해침으로 인한 염분도 상승으로 수서생물은 담수종에서 기수종 및 해수종으로 천이되고 있다. 섬진강 하구의 대표적인 수서생물인 재첩은 염분도 상승에 따라 폐각을 닫고 모래층으로 이동하는 특성을 보이고 있다. 이러한 관점에서 본 연구는 감조하천 구간에서의 취수장의 취수 규모에 따른 염분도 변화특성을 살펴보고, 하구 수서생물생활환경에 적합한 염분도를 유지할 수 있는 합리적인 취수장 운영방안을 마련하는 데 있다. 이를 위해 과거 취수장 상류의 유출량에 따른 취수규모별 하구 염분도 변화 특성을 분석하였다.

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Stratigraphic Analysis on Paleofluvial Outcrop underJeongok Basalt Layer in the Chugaryeong Rift Valley, Central Korea (추가령 열곡 내 전곡 현무암층 하부 고하성층 노두 층서 분석)

  • Lee, Min-Boo;Lee, Gwang-Ryul
    • Journal of The Geomorphological Association of Korea
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    • v.20 no.3
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    • pp.55-63
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    • 2013
  • The study deals with the geochemical analyses on the stratigraphy and sedimentation of the paleofluvial outcrop under Jeongok basalt layer in Chugaryeong Rift Valley. The results of field survey and analysis show that the paleofluvial sand and gravel layers had been constructed before the arrival of basaltic lava in Jeongok area of Hantan River valley in central Korea. XRF, for the main elements analysis, results present that JG2-3, a test sample from basalt weathering layer, has different characteristics from 5 other samples in the aspects of chemical weathering levels. ICP-MS, for analysis of the rare earth elements analysis, estimates that gravel layer, in the lowest part of the outcrop, had been originated from pre-lava bedrocks near the upper reach of the Hantan River, so the layer is almost not related to basalt layers. Finally, the OSL dating results in paleofluvial sedimentation had been in process until nearly 40,000 BP, before formation of lava plateau in the Jeongok area.

A hybrid RANS/LES Investigation of Backward-facing Step Flow (후방계단흐름의 하이브리드 RANS/LES 연구)

  • Yoo, Donggeun;Paik, Joongcheol
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.105-105
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    • 2019
  • 보나 여수로와 같은 수공구조물의 주변에서 발생하는 흐름 거동은 구조물 모서리에서 발생하는 흐름분리(flow separation)와 이에 따른 전단층(shear layer)과 재순환(recirculation) 흐름 영역의 발달 그리고 분리된 흐름의 재부착(reattachment)이 특징이다. 공학적으로 난류의 해석에 있어서 이러한 흐름 거동들을 정확하게 예측하는 것은 수공구조물 설계에 있어서 중요하다. 이 연구에서는 흐름 분리와 재순환 영역의 발달 그리고 흐름 재부착을 포함하는 후방계단(backward-facing step) 흐름을 155,000의 레이놀즈수 조건에서 하이브리드 RANS/LES 모델을 적용하여 해석결과를 평가한다. 하이브리드 모델로는 벽에 인접한 격자의 해상도에 상대적으로 민감하지 않은 SST(shear-stress transport) 난류 모델을 이용하는 DES(detached-eddy simulation) 기법을 적용하였다. 계단 높이가 h인 계산영역은 흐름방향 길이가 34h, 높이는 계단 상류와 하류에서 각각 1h와 2h 그리고 폭은 $2{\pi}$이다. 계단은 상류단으로부터 10h 하류부 지점에 위치한다. 경계조건으로 상부와 하부 벽면에 대해서는 비활조건을 적용한다. 상류부 수로에서 완전 발달한 흐름을 재현하기 위해서 유입경계조건은 유입부 하류 $2{\pi}h$ 지점에서 계산된 유속과 난류량을 매핑(mapping)기법을 이용하여 반복적으로 적용한다. 총 3.1백만개와 7.3백만개의 셀로 계산영역을 구현한 두 개의 계산격자 그리고 약 3.1백만개의 셀을 이용했지만 벽면 근처에서의 격자 구성을 다른 방식으로 설정한 두 가지 격자를 이용하여 격자 해상도가 DES 수치해석 결과에 미치는 영향을 분석하였다. 수치해석결과는 본 연구에서 상류단 조건으로 적용한 매핑기법이 대상 수로에서 완전 발달한 흐름을 잘 재현함을 보여주며, 합리적인 DES 해석 결과를 얻기 위해서는 벽에 수직한 방향으로 적절한 격자의 해상도와 분포가 필요함을 보여준다.

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Study on gatekeeping in selecting process of people in the news: Based on Social Capital theory (인물뉴스의 특성과 결정요인 연구: 사회자본(Social Capital) 이론을 중심으로)

  • Lee, Wan-Soo
    • Korean journal of communication and information
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    • v.32
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    • pp.295-332
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    • 2006
  • This study inquires at behavior and attitude of gatekeepers at major Korean media in the process of selecting and covering newsmakers, with focusing on factors, paths and practices in making news on the people. The study assumes that gatekeepers' social networking process with social elites, based on birth places, alma mater and kinship, plays great role in making people in the news. The study applies methods of in-depth interviews with people-page gatekeepers and content analysis of news on newsmakers. The in-depth interviews and content analysis unveil that people-page gatekeepers tend to support high society and social elite group. Furthermore, through the process of news-making, the gatekeeper group shares social capital such as economic exchanges and socio-political influences with social elite group. The result of interviews and analysis confirm that social networking based on personal affiliation plays as an important factor in selecting and covering newsmakers. With in-depth analysis of news contents, the study finds out that social elite groups of top government officials, corporate CEOs, medical doctors, lawyers, judges, prosecutors, college professors, cultural celebrities and journalists, who are predominantly male, appear on people pages much frequently out of proportion. The content analysis also reveal that 'personal news,' which cover personal and private life or unilaterally promote newsmakers predominate in terms of frequency and amount over socially-important or pubic-interested 'public news.' In terms of news values, fragmentary news composed of sensational, personal and gossiping elements appear more frequently than socially-meaningful news with strong social issues and public messages.

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An Experimental Study of Mutual Relation between Wake and Boundary Layer of a Flat Plate; Mean Velocity Field (평판 경계층과 후류와의 상호관계에 관한 연구; 평균속도장)

  • Kim, Dong-Ha;Chang, Jo-Won
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.10
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    • pp.1-11
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    • 2004
  • An experimental study was carried out to investigate the influence of flow conditions of a boundary layer on the near-wake of a flat plate. Various attaching positions of tripping wires were selected to change flow conditions on a boundary layer. Laminar, transitional, and turbulent boundary layer conditions at 0.98C from the leading edge are imposed to investigate the evolution of symmetric and asymmetric wake. An x-type hot-wire probe(55P61) is employed to measure at 8 stations of the near-wake region. Measured mean velocity distributions are presented in terms of similarity parameter. It is found that the symmetric wake collapses well to the universal profile in the central part of the wake. However, the universal profile is not suitable in describing an asymmetric wake.

A Study on Eclecticism of Newport Mansions in Rhode Island (미국 로드아일랜드 뉴포트 맨션의 절충주의에 관한 연구)

  • Kim, Jin-Hyung
    • Proceedings of the KAIS Fall Conference
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    • 2009.12a
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    • pp.37-40
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    • 2009
  • 미국 뉴포트의 주택들은 20세기를 전후로 하는 시기에 당시 최상류층의 휴양용 저택들로서, 미국의 절충주의 건축을 대표할 수 있는 특징을 갖고 있는 주택들이다. 본 연구에서는 미국에서 유럽의 건축적 전통과 영향을 절충주의적 철학에 따라 자신들의 형식으로 완성한 양식상의 전개를 살펴보고자 한다. 단순히 외국의 건축으로서 보다는 전통적 건축보다 외국의 영향에 의한 근대건축 문화를 이룩한, 우리나라의 건축 양식적 문제를 상호 비교하여 살펴보는 한 사례가 될 수 있을 것으로 본다.

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Measurements of Streambed Hydraulic Conductivity Using Drive-point Piezometers and Seepage Meters in the Upper Reaches of Anseong Stream (관입형 피조미터와 시피지미터를 이용한 안성천 상류구간 하상 수리전도도 측정)

  • Lee, Jeongwoo;Chun, Seon Geum;Yi, Myeong Jae;Kim, Nam Won;Chung, Il-Moon;Lee, Min Ho
    • The Journal of Engineering Geology
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    • v.25 no.3
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    • pp.413-420
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    • 2015
  • Streambed hydraulic conductivity along the upper reaches of the Gongdo stage of Anseong Stream was estimated through measurements of stream-aquifer exchange rates (using a seepage meter) and vertical hydraulic gradients (using a manually driven piezometer). From the measured data, it was found out that the stream-aquifer exchange rates varied from -1.55 × 10-6 to 1.77 × 10-5 m/s, the corresponding vertical hydraulic gradient varied from -0.122 to 0.030, and the values of the streambed vertical hydraulic conductivity were estimated from 1.77 × 10-5 to 1.97 × 10-3 m/s, with variations representing local differences. The results are within the general range of streambed hydraulic conductivity values suggested by Calver (2001) and are slightly higher than values previously measured at other stream sites in Korea. The combined use of a drive-point piezometer and seepage meter (both constructed of high-strength stainless steel) is expected to be of practical use in the estimation of streambed hydraulic conductance, given the durability and portability of the instruments.

Streamflow Estimation using Coupled Stochastic and Neural Networks Model in the Parallel Reservoir Groups (추계학적모형과 신경망모형을 연계한 병렬저수지군의 유입량산정)

  • Kim, Sung-Won
    • Journal of Korea Water Resources Association
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    • v.36 no.2
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    • pp.195-209
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    • 2003
  • Spatial-Stochastic Neural Networks Model(SSNNM) is used to estimate long-term streamflow in the parallel reservoir groups. SSNNM employs two kinds of backpropagation algorithms, based on LMBP and BFGS-QNBP separately. SSNNM has three layers, input, hidden, and output layer, in the structure and network configuration consists of 8-8-2 nodes one by one. Nodes in input layer are composed of streamflow, precipitation, pan evaporation, and temperature with the monthly average values collected from Andong and Imha reservoir. But some temporal differences apparently exist in their time series. For the SSNNM training procedure, the training sets in input layer are generated by the PARMA(1,1) stochastic model and they covers insufficient time series. Generated data series are used to train SSNNM and the model parameters, optimal connection weights and biases, are estimated during training procedure. They are applied to evaluate model validation using observed data sets. In this study, the new approaches give outstanding results by the comparison of statistical analysis and hydrographs in the model validation. SSNNM will help to manage and control water distribution and give basic data to develop long-term coupled operation system in parallel reservoir groups of the Upper Nakdong River.

Experimental Study on the Effects of Upstream Periodic Wakes on Aerofoil-Boundary Layer and Loss (주기적 상류 후류의 익 경계층과 손실에 미치는 영향에 대한 실험적 연구)

  • Rim, In-Won;Cho, Kang-Rae;Joo, Won-Gu
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.661-667
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    • 2001
  • This paper is concerned with the effects of periodically approaching upstream wakes on cascade-flow and loss. The reduced frequency of the periodic wakes was varied in the narrow range from 0.5 to 0.7. According to a wake-passing through the cascade, two velocity deficits appear near the boundary layer contour in the downstream from about 60% chord-length. The first velocity deficit is caused by a periodic wake and the second one appears after some delayed time. The second velocity deficit may be interpreted as the results of reattachment of flow-separation. The higher reduced frequency decreases the duration time of separation appearance and the lesser loss of aerofoil is resulted.

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