• Title/Summary/Keyword: near stream

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The Effect of the Secondary Annular Stream on Supersonic Jet

  • Lee, Kwon-Hee;Toshiaki Setoguchi;Shigeru Matsuo;Kim, Hyeu-Dong
    • Journal of Mechanical Science and Technology
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    • v.17 no.11
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    • pp.1793-1800
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    • 2003
  • The present study addresses an experimental investigation of the near field flow structures of supersonic, dual, coaxial, free, jet, which is discharged from the coaxial annular nozzle. The secondary stream is made from the annular nozzle of a design Mach number of 1.0 and the primary inner stream from a convergent-divergent nozzle. The objective of the present study is to investigate the interactions between the secondary stream and inner supersonic jets. The resulting flow fields are quantified by pitot impact and static pressure measurements and are visualized by using a shadowgraph optical method. The pressure ratios of the primary jet are varied to obtain over-expanded flows and moderately under-expanded flows at the exit of the coaxial nozzle. The pressure ratio of the secondary annular stream is varied between 1.0 and 4.0. The results show that the secondary annular stream significantly changes the Mach disc diameter and location, and the impact pressure distributions. The effects of the secondary annular stream on the primary supersonic jet flow are strongly dependent on whether the primary jet is under-expanded or over-expanded at the exit of the coaxial nozzle.

Evaluation of Effects of Groundwater Pumping Near Stream Using Analytical Model (해석적 모형에 의한 하천변 지하수 양수 영향 분석)

  • Lee, Jeongwoo;Chung, Il-Moon;Kim, Nam Won;Lee, Min Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.4
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    • pp.617-625
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    • 2016
  • The objective of this study was to evaluate the groundwater drawdown and streamflow depletion due to each groundwater pumping from 110 wells located near stream using the Hunt's analytical solution (1999). The calculated results revealed that the streamflow depletion rate divided by the pumping rate for each well location mostly exceeded about 80% of pumping rate on average for 5 years. The results also showed that the stream boundary condition has made the influence distance shorter and the drawdown distribution skewed except for the streambed hydraulic conductivity and the stream bed factor (SBF) lower than $1.0{\times}10^{-9}m/s$ and 1.0, respectively. It was found that the groundwater pumping has significant impacts on the stream depletion showing above 80 % of stream depletion rate when the streambed hydraulic conductivity is higher than $1.0{\times}10^{-7}m/s$ and the stream depletion factor(SDF) is lower than 100. However, for other conditions, the SDF is not sufficient to be used as a criterion for determining whether the pumping has great impacts on stream depletion or not. Furthermore, the variation of the streambed hydraulic conductance has little change in stream depletion rate for the condition that the stream width is greater than 400 m.

First Reliable Record of an Eleotrid Fish, Eleotris oxycephala (Perciformes: Eleotridae) from the Lower Reach of Jwagwang Stream Near Busan, Korea (경남 기장군 좌광천에서 채집된 구굴무치 Eleotris oxycephala의 기재)

  • Kim, Byung-Jik;Jang, Min-Ho;Yoon, Ju-Duk;Song, Ho-Bok
    • Korean Journal of Ichthyology
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    • v.26 no.3
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    • pp.230-234
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    • 2014
  • Eleotris oxycephala was described in detail as the first reliable record from Korea based on a single specimen (62.1 mm SL) collected from the lower reach of Jwagwang stream near Busan, Korea. The specimen is easily distinguished from three congeners occurring in the northern West Pacific by having separation between two rows of sensory papillae on opercle and the fourth row of the papillae on cheek not extending beyond the 11th longitudinal sensory-papillae.

Change of Groundwater-Streamflow Interaction according to Groundwater ion in a Green House Land (비닐하우스 지역의 지하수 양수에 따른 지하수-하천수 상호 유동 변화 분석)

  • Kim, Nam Won;Lee, Jeong Woo;Chung, Il Moon;Kim, Chang Hwan
    • Journal of Korea Water Resources Association
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    • v.45 no.10
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    • pp.1051-1067
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    • 2012
  • Increased use of water curtain facilities to keep green house warm during winter cultivation has been known to cause excessive groundwater ion which might lead to decline of groundwater level, resulting in streamflow depletion. Therefore it is required to quantitatively assess the effects of groundwater ion on the streamflow depletion such as magnitude and extent. The objective of this study is to assess the change of stream-aquifer interaction according to groundwater ion near stream. To this end, a green house cultivation land in Sooha-ri, Sindun-myun, Icheon-si, Gyonggi-do was selected as a field experimental site, and monitoring wells were established near and within stream to observe the water level and temperature changes over a long period of time. From the observed water level and temperature data, it was found that the river reach of interest changed to a losing stream pattern during the winter cultivation season due to groundwater level decline around pumping wells near the stream. The continuous exchange rates between stream and aquifer were estimated by plugging the observed water level data series into the experimental relation between head difference and exchange rate, showing the streamflow depletion by 16% of the groundwater pumping rate in Feb, 2011.

임기광산 폐석 및 퇴적물의 산성배수발생 능력 평가

  • 정영욱;임길재;지상우;민정식;최용석
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2004.09a
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    • pp.390-393
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    • 2004
  • This study was carried out to evaluate the acid producing potential of geological materials such as pit wall, waste rock and stream sediments near the abandoned Imgi mine. The 17 samples used in this study were collected and then treated by static test such as Acid Base Accounting and etc. Samples of pit wall and waste rocks with high S content display a NAGpH values below 4.5 and net acid potential. Therefore some cost effective measures such as capping and groudwater flow barriers, will be required to reduce the impacts of ARD from the waste rock impoundment and the pit wall on near the stream.

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Predicting the likelihood of impaired stream segments using Geographic Information System on Abandoned Mine Land in Gangwon Province

  • Lee, Ju-Young;Yang, Jung-Suk;Choi, Jae-Young
    • Proceedings of the Korea Water Resources Association Conference
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    • 2007.05a
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    • pp.1081-1083
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    • 2007
  • The study in river basin has been performed for the identify water quality impaired stream segments, to create a priority ranking of those segments, and to calculate the heavy metal ion distribution for each impaired segment based on chemical and physical water quality standards. Two methods for modeling the potential area-specific heavy metal distribution are pursued in this study. First, a novel approach focuses on distance. Heavy metal distribution can be associated with a particular small geographic area. Based on the derived estimates an distribution map can be generated. Second, the approach is used the near watershed by means of kriging interpolation algorithm. These approaches provide an alternative distribution mapping of the area. The exposure estimates from both of these modeling methods are then compared with other environmental monitoring data. A GIS-based model will be used to mimic the hierarchical stream structure and processes found in natural watershed. Specifically, the relationship between landscape variables and reach scale habitat conditions most influential found in the Abandoned mine will be explored.

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A Case Study on Dry Stream Protection Design Using Causes Analysis of the Dry Stream Weakness Section (하천 건천화 취약구간 원인 분석을 통한 방지 대책: 설계사례)

  • Yoo, Chan-Ho;Park, Se-Young;Kang, Moon-Gu;Hwang, Jung-Soon;Oh, Byung-Sam
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1494-1501
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    • 2008
  • Recently, the demand of water resources is constantly increasing due to the substantial increase of population, economy, and living standard. However, it is expected that the water resources should undergo serious problems of poor quality of water as well as shortage of water supply in the near future. Additionally, thoughtless groundwater development have caused to dry river and stream. In this study, the effectiveness of dry stream protection plan is evaluated by using 3-D groundwater flow modeling for the study area which is located in Namyangju of Kyoungi Province. Aquifer tests are performed to obtain the input data of the model. To analyze causes of dry stream using modeling results that water balance is analyzed for situations of before and after closing the wells.

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Evidence of Stellar Substructures on the Near-infrared Image of M31 System

  • Kang, Minhee;Chun, Sang-Hyun;Sohn, Young-Jong
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.1
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    • pp.41.2-41.2
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    • 2014
  • Hierarchical merging scenario indicates that galaxies go through major and minor merger events during their formation and evolution. As a result of the merging, substructural features of remnants such as stellar stream are shown around a current galaxy system. To find evidence of stellar substructures on M31 system, we used the near-infrared images of JHK filters obtained from the Wide Field Camera (WFCAM) at UKIRT 3.8m. A total sky coverage is an area of about$ 4.5^{\circ}{\times}6^{\circ}$ around M31. Indeed, M31 system which consists of several satellite systems contains stellar substructures such as giant stellar stream, loops, and spurs. By analysing stellar populations on the near-infrared color-magnitude diagrams, we selected member star candidates of each stellar substructure, from which we map out spatial distribution of stars in the vicinity of M31 system. Here, we present spatial density distribution maps of stars on each substructure over the entire field of M31 system. Also, we discuss the possible origin of the substructures and the implications on the galaxy assembly process.

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