• Title/Summary/Keyword: inflow temperature

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Development of the Inflow Temperature Regression Model for the Thermal Stratification Analysis in Yongdam Reservoir (용담호 수온성층해석을 위한 유입수온 회귀분석 모형 개발)

  • Ahn, Ki Hong;Kim, Seon Joo;Seo, Dong Il
    • Journal of Environmental Impact Assessment
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    • v.20 no.4
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    • pp.435-442
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    • 2011
  • In this study, a regression model was developed for prediction of inflow temperature to support an effective thermal stratification simulation of Yongdam Reservoir, using the relationship between gaged inflow temperature and air temperature. The effect of reproductability for thermal stratification was evaluated using EFDC model by gaged vertical profile data of water temperature(from June to December in 2005) and ex-developed regression models. Therefore, in the development process, the coefficient of correlation and determination are 0.96 and 0.922, respectively. Moreover, the developed model showed good performance in reproducing the reservoir thermal stratification. Results of this research can be a role to provide a base for building of prediction model for water quality management in near future.

A Study on the Oil Temperature Control Errors of Precision Oil Coolers (정밀 오일냉각기의 오일온도 제어오차에 관한 연구)

  • 이상호;이찬홍;김갑순
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.451-454
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    • 2003
  • The Oil Coolers is very important unit for the stable thermal performance in machine tools, semiconductor equipments and high precision measuring systems. To select a proper oil cooler for the temperature control of core unit in a machine, not only cooling ability but also static and dynamic sensitivity of temperature sensors are considered. In this paper, the relationship between cooling ability and inflow oil temperature is identified. The cooling ability is increased with the increase of inflow oil temperature. The oil temperature control errors of a cooler are influenced by mainly sensitivity of temperature sensors and heating velocity in a machine. The validity of error cause analysis for temperature control is proved by real cooling experiments with inflow and outflow temperature sensors.

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The Study of Pressurant Inflow Prediction Using Temperature Change of Geostationary Satellite Propellant System (정지궤도 인공위성 추진시스템의 온도변화를 통한 배관내 가압제 유입 예측기법 연구)

  • Park Eung Sik;Jun Hyoung Yoll;Park Bong Kyu;Han Cho Young;Choi Seong Bong;Kim Yong Min
    • 한국전산유체공학회:학술대회논문집
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    • 2005.04a
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    • pp.96-99
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    • 2005
  • The geostationary satellite propulsion system has thermistors which can measure liquid propellant temperature at tanks, pipes and etc. In the satellite propulsion system with several tanks, the propellant in the tanks is moved by temperature change and this temperature pattern is constant. In this paper, the temperature change pattern of KOREASAT 1 propulsion system is compared and the prediction study of pressurant inflow using temperature change of geostationary satellite propulsion system is described.

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A Numerical Study on Effects of Flow Through Openings on Convection (개구부의 유동이 대류에 미치는 영향에 관한 수치연구)

  • 박외철;이경아
    • Journal of the Korean Society of Safety
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    • v.15 no.3
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    • pp.52-56
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    • 2000
  • The finite control volume method was utilized to investigate the effects of flow through openings on convection in an enclosure. Flow patterns and temperature distribution were compared for non-dimensional inflow velocity U=20, 40, 60 at Ra=$10^4$ and $5\times10^4$, respectively. The inflow velocity influenced temperature distribution in the enclosure significantly and lowered temperature on the top wall. The flow through openings forced the position of the highest temperature on the top wall to move toward the outflow opening.

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One-month lead dam inflow forecast using climate indices based on tele-connection (원격상관 기후지수를 활용한 1개월 선행 댐유입량 예측)

  • Cho, Jaepil;Jung, Il Won;Kim, Chul Gyium;Kim, Tae Guk
    • Journal of Korea Water Resources Association
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    • v.49 no.5
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    • pp.361-372
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    • 2016
  • Reliable long-term dam inflow prediction is necessary for efficient multi-purpose dam operation in changing climate. Since 2000s the teleconnection between global climate indices (e.g., ENSO) and local hydroclimate regimes have been widely recognized throughout the world. To date many hydrologists focus on predicting future hydrologic conditions using lag teleconnection between streamflow and climate indices. This study investigated the utility of teleconneciton for predicting dam inflow with 1-month lead time at Andong dam basin. To this end 40 global climate indices from NOAA were employed to identify potential predictors of dam inflow, areal averaged precipitation, temperature of Andong dam basin. This study compared three different approaches; 1) dam inflow prediction using SWAT model based on teleconneciton-based precipitation and temperature forecast (SWAT-Forecasted), 2) dam inflow prediction using teleconneciton between dam inflow and climate indices (CIR-Forecasted), and 3) dam inflow prediction based on the rank of current observation in the historical dam inflow (Rank-Observed). Our results demonstrated that CIR-Forecasted showed better predictability than the other approaches, except in December. This is because uncertainties attributed to temporal downscaling from monthly to daily for precipitation and temperature forecasts and hydrologic modeling using SWAT can be ignored from dam inflow forecast through CIR-Forecasted approach. This study indicates that 1-month lead dam inflow forecast based on teleconneciton could provide useful information on Andong dam operation.

A Study on the Relationship between Cyanobacteria and Environmental Factors in Yeongcheon Lake (영천호에서 남조류 발생과 환경요인의 관련성 연구)

  • Lee, Hyeon-Mi;Shin, Ra-Young;Lee, Jung-Ho;Park, Jong-geun
    • Journal of Korean Society on Water Environment
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    • v.35 no.4
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    • pp.352-361
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    • 2019
  • The purpose of this study is to analyze the characteristics and correlations of the Yeongcheon Lake in order to reduce the occurrence of harmful cyanobacteria. In this study, we investigated the water quality and phytoplankton of the lake from May to November in 2017. Correlation and data mining analyses were performed to analyze the relationship between the two factors. The water temperature was lowest at the point where the Yeongcheon Lake inflow occurs at Imha Lake. It was highest at the point where the outflow occurs to Angye Lake. The pH was also highest at the outflow point, but in the case of DO, it was highest at the midpoint between the inflow and outflow. The main cyanobacteria that emerged during the study period were Oscillatorialimosa, Microcysti saeruginosa and Aphanizomenon flos-aquae. As a result of correlation analysis, the water temperature, inflow, COD loading, TOC loading at the inflow point of the Yeongcheon Lake were the items that were related to the harmful cyanobacteria. The data mining analysis indicated that the TP loading and harmful cyanobacteria in the inflow point of the Yeongcheon Lake were influential on the detrimental cyanobacteria in the Yeongcheon Lake outflow point. When the TP loading was less than 39.0 kg/day at the inflow site, it was expected that the amount of harmful cyanobacteria could be maintained below 10,000 cells/mL.

Study on Temperature Variation by Greenhouse Soil Warming System Using Solar Thermal Energy (2) - Required Energy per Unit Area for Soil Warming - (태양열을 이용한 시설재배 지중변온가온의 토양 온도특성 연구(2) - 지중변온가온의 단위면적당 소요에너지 -)

  • Kim, Jin-Hyun;Kim, Tae-Wook;Nah, Kyu-Dong;Kim, Tae-Soo;Kim, Eun-Tae;Chung, Suk-Hyun
    • Journal of Biosystems Engineering
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    • v.35 no.1
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    • pp.46-52
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    • 2010
  • The temperature of root zone was known as an important factor for the growth of crops and reduction of energy in greenhouse. The purpose of this study was to design the apposite inflow of calories per the unit area by comparison of temperature in the warmed and non-warmed soil. The energy needed for soil warming about pipe length showed the change of temperature on inflow and outflow as $2^{\circ}C{\sim}3^{\circ}C$(average $2.5^{\circ}C$). Therefore, the inflow per the unit hour was 3,450, 57,5 kcal/$h{\cdot}m^2$ on soil heating respectively. The non-warmed soil temperature in greenhouse made a difference by depth and it was partially affected inner temperature under 15 cm, but it was not above 15 cm. The soil temperature would be raised over $5^{\circ}C$ than non-warmed soil to increase effect of soil warming. Therefore, the inflow per the unit area that should be provided was about 100 kcal/$h{\cdot}m^2$.

Thermal Stratification Effects Near an Interface by Horizontal Inflow of Cold Water in Thermal Storage Tank (냉수가 수평유입되는 열저장탱크의 중간 경계면 부근에서의 열성층 효과)

  • Hwang, Sung-Il;Pak, Ee-Tong
    • Solar Energy
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    • v.8 no.2
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    • pp.46-56
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    • 1988
  • This investigation concerns thermal stratification of the water due to the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the water in the test tank (1m wide, 1m high, 2.1m long) and the temperature of the inflow water into the tank; flow rate of circulating water and height of the sink diffuser in the test tank. The additional objectives was to observe a stratification phenomena near an interface by measuring the velosities and the temperature difference and investigate an availabilities of the better effective hot water through establishing thermocline near an interface around the bottom of the tank. Following results were obtained through the experiments. 1. When the flow rate was constant and the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the flow in the test tank and the temperature of the inflow water increased by 5.6, 9.5, 13.5($^{\circ}C$), obtained the better effective advantage of hot water and the stress near an interface increased gradually. 2. When the ${\Delta}T=T_{\infty}-T_i$ was constant and flow rate increased by 4.0, 4.8, 6.4, 8.0 (LPM), obtained the better effective advent age of hot water and the mean stress near an interface increased gradually. 3. When the height of the sink diffuser was 25cm from tank bottom in comparison with 50cm, obtained the better effective advantage of hot water and the mean stress near an interface increased.

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Environmental Evaluation of Fish Aquafarm off Baegyado in Yeosu by Multivariate Analysis (다변량분석에 의한 여수 백야도 어류양식장의 해양 환경분석)

  • LEE, Chang-Hyeok;KANG, Man-Gu;LIM, Su-Yeon;KIM, Jae-Hyun;SHIN, Jong-Ahm
    • Journal of Fisheries and Marine Sciences Education
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    • v.29 no.3
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    • pp.785-798
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    • 2017
  • This study was conducted to evaluated the surface(10 variables) and bottom(10 variables) water quality, and sediment(3 variables) in the cage fish farm off Baegyado in Gamak Bay using a multivariate analysis from January 2013 to November 2014. Generally, the environmental data did not show a certain tendency by months during two years investigated. The pairwise simple correlation matrices among variables were also shown. The first four principal components of the surface water in 2013 explain 93% of the total sample variance; the first principal component($z_1$) showed the freshwater inflow and/or precipitation, $z_2$, $z_3$ and $z_4$ related to freshwater inflow and/or precipitation, organic matters and eutrophy, respectively; the first four principal components of the bottom water in 2013 explain 93% of the total sample variance; the $z_1$, $z_2$ and $z_4$ related to freshwater inflow and/or precipitation, and $z_3$ water temperature. In 2014, at the surface water the first three principal components explain 87%; the $z_1$, $z_2$ and $z_3$ related to water temperature, eutrophy and freshwater inflow and/or precipitation, respectively; at the bottom water the first three principal components explain 93%; $z_1$, $z_2$ and $z_3$ related to water temperature, freshwater inflow and/or precipitation and eutrophy. Half of the principal components related to freshwater inflow and/or precipitation.

Forecasting of Seasonal Inflow to Reservoir Using Multiple Linear Regression (다중선형회귀분석에 의한 계절별 저수지 유입량 예측)

  • Kang, Jaewon
    • Journal of Environmental Science International
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    • v.22 no.8
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    • pp.953-963
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    • 2013
  • Reliable long-term streamflow forecasting is invaluable for water resource planning and management which allocates water supply according to the demand of water users. Forecasting of seasonal inflow to Andong dam is performed and assessed using statistical methods based on hydrometeorological data. Predictors which is used to forecast seasonal inflow to Andong dam are selected from southern oscillation index, sea surface temperature, and 500 hPa geopotential height data in northern hemisphere. Predictors are selected by the following procedure. Primary predictors sets are obtained, and then final predictors are determined from the sets. The primary predictor sets for each season are identified using cross correlation and mutual information. The final predictors are identified using partial cross correlation and partial mutual information. In each season, there are three selected predictors. The values are determined using bootstrapping technique considering a specific significance level for predictor selection. Seasonal inflow forecasting is performed by multiple linear regression analysis using the selected predictors for each season, and the results of forecast using cross validation are assessed. Multiple linear regression analysis is performed using SAS. The results of multiple linear regression analysis are assessed by mean squared error and mean absolute error. And contingency table is established and assessed by Heidke skill score. The assessment reveals that the forecasts by multiple linear regression analysis are better than the reference forecasts.