• Title/Summary/Keyword: Flow stream

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A Study on Nitrification in tim Main Stream of the Naktong River (낙동강 본류에 대한 질화작용의 조사연구)

  • 김형섭;이홍근
    • Journal of Environmental Health Sciences
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    • v.9 no.1
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    • pp.1-13
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    • 1983
  • This study was carried out to investigate nitrification in the main stream of the Naktong river for two times, 12-13 August and 23-26 September 1982. The results of this study were as follows : 1. The increase of nitrogen concentration was due to inflow of Geumho river, which was polluted by the municipal and industrial wastewater of Daegu city. 2. The rate constant of ammonia calculated for three reaches was high according to the stream flow and was eminently low in the reach from Goroung to Gangjung. (0.068-0.116 $day^{-1}$). This phenomena might be attributed to the sublethal or even lethal effect upon aquatic life by relatively low DO concentration and high heavy metal concentration. 3. DO consumption rate by nitrification was highest for the reach from Goroung to Daeam where was affected by Geumho river. (56.7-147.8%). This phenomena might be attributed to low DO concentration and high nitrogen concentration. Especially, the less stream flow was, the higher DO consumption was. And so, nitrification in the station where is low DO concentration, especially under the low flow condition, might cause more serious water quality management problem. Therefore, for the purpose of effective conservation of water quality in the Naktong river, it was suggested that We have more concern about the nitrogen compound, and more study on the nitrification phenomena.

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A Human Movement Stream Processing System for Estimating Worker Locations in Shipyards

  • Duong, Dat Van Anh;Yoon, Seokhoon
    • International Journal of Internet, Broadcasting and Communication
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    • v.13 no.4
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    • pp.135-142
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    • 2021
  • Estimating the locations of workers in a shipyard is beneficial for a variety of applications such as selecting potential forwarders for transferring data in IoT services and quickly rescuing workers in the event of industrial disasters or accidents. In this work, we propose a human movement stream processing system for estimating worker locations in shipyards based on Apache Spark and TensorFlow serving. First, we use Apache Spark to process location data streams. Then, we design a worker location prediction model to estimate the locations of workers. TensorFlow serving manages and executes the worker location prediction model. When there are requirements from clients, Apache Spark extracts input data from the processed data for the prediction model and then sends it to TensorFlow serving for estimating workers' locations. The worker movement data is needed to evaluate the proposed system but there are no available worker movement traces in shipyards. Therefore, we also develop a mobility model for generating the workers' movements in shipyards. Based on synthetic data, the proposed system is evaluated. It obtains a high performance and could be used for a variety of tasksin shipyards.

Active Control Methods for Drag Reduction in Flow over Bluff Bodies (뭉툭한 물체 주위 유동에서 항력 감소를 위한 능동 제어 방법)

  • Choi Haecheon
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.11-16
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    • 2002
  • In this paper, we present two successful results from active controls of flows over a circular cylinder and a sphere for drag reduction. The Reynolds number range considered for the flow over a circular cylinder is 40-3900 based on the free-stream velocity and cylinder diameter, whereas for the flow over a sphere it is $10^{5}$ based on the free-stream velocity and sphere diameter. The successful active control methods are a distributed (spatially periodic) forcing and a high-frequency (time periodic) forcing. With these control methods, the mean drag and lift fluctuations decrease and vortical structures are significantly modified. For example, the time-periodic forcing at a high frequency (larger than 20 times the vortex shedding frequency) produces $50{\%}$ drag reduction for the flow over a sphere at $Re=10^{5}$. The distributed forcing applied to the flow over a circular cylinder results in a significant drag reduction at all the Reynolds numbers investigated.

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A Numerical Analysis for Prediction of Flow Rate of the Motor Cooling Fan (전동기 냉각팬의 유량예측을 위한 수치해석)

  • Lee, Sang-Hwan;Kang, Tae-In;Ahn, Chel-O;Seo, In-Soo;Lee, Chang-Joon
    • 유체기계공업학회:학술대회논문집
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    • 2005.12a
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    • pp.670-677
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    • 2005
  • In this study, we analyzed the three dimensional unsteady flow field around the motor cooling fan using the unsteady lifting surface theory. We obtained the flow rate for various geometries of fan from the calculated results of velocity field. For the data of design parameter and rotating speed(rpm) of the fan, we can predict the flow rate of the motor cooling fan with thin thickness through numerical analysis without the experimental data of the free stream velocity which is a boundary condition of flow field. the numerical results showed the flow rate within 10% of error in comparison with experimental results. The radial fans, which are often used as internal motor fan were also investigated with the same procedure.

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Calculation of the internal flow in a fuel nozzle (연료노즐 내부유동 현상의 수치해석)

  • Gu, Ja-Ye;Park, Jang-Hyeok;O, Du-Seok;Jeong, Hong-Cheol
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.6
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    • pp.1971-1982
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    • 1996
  • The breakup of liquid jet is the result of competing, unstable hydrodynamic forces acting on the liquid jet as it exit the nozzle. The nozzle geometry and up-stream injection conditions affect the characteristics of flow inside the nozzle, such as turbulence and cavitation bubbles. A set of calculation of the internal flow in a single hole type nozzle were performed using a two dimensional flow simulation under different nozzle geometry and up-stream flow conditions. The calculation showed that the turbulent intensity and discharge coefficient are related to needle position. The diesel nozzle with sharp inlet under actual engine condition has possibility of cavitation, but round inlet nozzle has no possibility of cavitation.

Open-channel discharges evaluation by the application of smart sensors

  • Khatatbeh, Arwa;Kim, Young-Oh
    • Proceedings of the Korea Water Resources Association Conference
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    • 2022.05a
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    • pp.138-138
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    • 2022
  • Understanding a stream's or river's discharge is essential for a variety of hydrological and geomorphological applications at various sizes. However, depending on the stream environment and flow conditions, it is crucial to use the appropriate techniques and instruments. This will ensure that discharge estimations are as reliable as possible. This study presents developed smart system for continuous measurement of open channel discharge and evaluate streamflow measurement over various techniques. This includes developed smart flow meter as flow point measurements, smart water level sensor (installed on Hydraulic Structure ? Weir) and current meters. Advantages and disadvantages of each equipment are presented to ensure that the most appropriate method can be selected. we found that smart water level sensor is more prominent once used during flood event as compared to smart flow meter and current meters, while current meters seems to show better accuracy once applied for open channel.

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Urban Stream Landscape Improvement After Natural-Style Stream Restoration - Case Study of Yangjae Stream, Seoul - (도시 자연형하천 공사 후의 경관개선방안 - 서울시 양재천을 사례로 -)

  • Kim, Sun-Gun;Kim, Go Eun;Lee, Ji Eun;Shin, Dong-Hoon;Lee, Kyoo-Seock
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.7 no.5
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    • pp.66-74
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    • 2004
  • Since 1960s urban streams in Seoul have been dried and polluted because of urbanization. So, these devastated urban stream environment need to be restored for the better life of residents. Since 1995 stream restoration project which is called Natural-Style Stream Project have begun. However, some projects focused on the restoration of park-style open space rather than restoration of stream environment. As a result there are some stream landscapes to be improved. Therefore, this study aims to investigate the current status of urban stream landscape after Natural Style Stream Project and to propose the alternatives for the urban stream landscape improvement. The study site is Yangjae stream, Seoul.

A Study on Anticipation System of Shudder Distinction by the Physical Shape Alteration in Static Condition (고정상태에서 신체 형태변화에 따른 떨림 판별의 예측시스템 연구)

  • Kim, Jeong-Lae;Choi, Jae-Sil;Hwang, Kyu-Sung
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.3
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    • pp.115-120
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    • 2017
  • Moving techniques is made up the physical moving status of the flow distinction modulus (FDM) and stream distinction modulus (SDM) on the shudder moving shape. Condition of the distinction modulus by the shudder moving shape is organized the dangle moving system. As to define the physical moving of special signal on the matter, we compared a shudder value of the flow distinction modulus on the flow state. The concept of stream distinction modulus is analyzed the reference of stream distinction signal and stream distinction signal by the stream state. For detecting a variation of the FDM-SDM of the maximum-minimum and average in terms of the moving shape, and shudder moving value that is a shudder value of the top variation of the $Top-{\varepsilon}$ MAX-MIN-AVG with $(-0.817){\pm}0.15$ units, that is a shudder value of the peripheral variation of the $Per-{\varepsilon}$ MAX-MIN-AVG with $(-2.53){\pm}(-0.11)$ units, that is a shudder value of the limbus variation of the $Lim-{\varepsilon}$ MAX-MIN-AVG with $(-0.29){\pm}0.03$ units, that is a shudder value of the center variation of the $Cen-{\varepsilon}$ MAX-MIN-AVG with $(-0.09){\pm}(-0.01)$ units. The dangle moving will be to assess at the capacity of the physical moving shape for the control degree of distinction modulus on the FDM-SDM that is showed the flow and stream shape by the distinction modulus system. Dangle distinction system is adjusted of a shape by the special moving and is included a shudder data of dangle moving modulus.

Assessment of changes on water quality and aquatic ecosystem health in Han river basin by additional dam release of stream maintenance flow (하천유지유량 추가 댐방류에 따른 한강유역의 수질 및 수생태계 건강성 변화 평가)

  • Woo, So Young;Kim, Seong Joon;Hwang, Sun Jin;Jung, Chung Gil
    • Journal of Korea Water Resources Association
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    • v.52 no.spc2
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    • pp.777-789
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    • 2019
  • The purpose of this study is to evaluate changes in water quality and aquatic ecosystem health by additional dam release of stream maintenance flow from multipurpose dams in Han river basin ($34,148km^2$) using SWAT (Soil and Water Assessment Tool). The period of additional release was spring (April to June) and autumn (August to October) to evaluate the changes with the data of aquatic ecosystem health survey. The amount of additional release was set proportional to the present dam release, and the maximum release amount was controlled not to exceed the officially notified stream maintenance flow from dam. The 10 percent to 50 percent additional releases showed that the stream water quality (T-N, $NH_4$, T-P, and $PO_4-P$) concentrations except $NO_3-N$ decreased in spring while increased in autumn period. Using the stream water quality results and applying with Random Forest algorithm, the grade of aquatic ecosystem health index (FAI, TDI, and BMI) was improved for both periods especially in the downstream of basin. This study showed that the additional release of stream maintenance flow was more effective in spring than autumn period for the improvement of water quality and aquatic ecosystem.

A Study on Water Environment and Benthic Macroinvertebrate Community in Reclaimed Wastewater Effluent Dominated Stream (하수처리수 방류 하천의 물환경과 저서성 대형무척추동물 군집 생태 연구)

  • Son, Jung-Won;Kwag, Jin-Suk;Cho, Gab-Je;Ryou, Dong-Choon
    • Journal of Korean Society on Water Environment
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    • v.37 no.3
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    • pp.190-203
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    • 2021
  • Water quality, benthic macroinvertebrate communities, and other factors were investigated to explore the effects of the effluent discharge from a sewage treatment plant into Jwagwang stream in Busan in 2019. During the study period, the flow rate of this stream was in the range of 10,400 m3/day to 52,200 m3/day except for the discharge of about 24,000 m3/day of the effluent. After discharge, the flow velocity increased by about 65% and the water depth increased by about 40%. At sites downstream of the discharge point, BOD, COD, TOC, T-N, T-P, and other water quality values were worse than those of the upstream sites. The periphytic algal chlorophyll-a concentrations in the natural substrata were higher than those of the upstream sites, especially in May and August. However, at sites downstream of the discharge point, the individual numbers of Annelida were decreased and individual numbers of the insecta of arthropoda were increased. Also, species numbers and the diversity and dominance indexes were improved in the sites downstream of the discharge point. The functional feeding groups (FFGs) of collector-filterers were increased and the habitat orientation groups (HOGs) of sprawlers, burrowers, and clingers were especially increased at the sites with additional reclaimed wastewater effluent flow. Regardless of the effluent discharge, BMI, an indicator of ecological stream health using benthic macroinvertebrate species, did not show large gaps between the study points. Although the water quality of the sites downstream of the discharge point was much worse than those upstream, their ecosystem soundness was better than those of the upstream sites from an ecological perspective.