• Journal of Applied Reliability
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• v.11 no.3
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• pp.281-291
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• 2011

This paper presents an accelerated life test of booster pump for home water purifier. The failure analysis shows that decreased flux due to the plastic deformation of bypass spring adjusting pressure is the predominant failure mechanism. An accelerated life test is designed and implemented to estimate the lifetime of the booster pump. Temperature, water pressure and voltage are selected as accelerating variables through the technical review about failure mechanism. It is assumed that the lifetimes of booster pumps follow lognormal distribution and the combination model of temperature and non-thermal stresses holds. The life-stress relationship, acceleration factor, and $B_{10}$ life at design condition are estimated by analyzing the accelerated life test data.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.77-81
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• 2010

This study carried out hydraulic model test for water circulation system in Cheongna district as part of Incheon Free Economic Zone. Canal way project of Cheongna was planned to establish for environment-friendly water circulation system, improve quality of life and diversification of traffic through using boat as a water-friendly international business city. The navigation canal, There are two intake facility in central park and it can purify water 15,000$m^3$ per day. After purify, water move to 8 facility of water culture area which supplies water in canal way. This process called water circulation system in cheongna. Also, there are several flow induction machine in canal way except south-north way. Therefore, this study will verify about validity of water circulation system's safety through hydraulic model test.

• Journal of Korea Water Resources Association
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• v.31 no.6
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• pp.709-725
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• 1998

The characteristics of storm and water quality are investigated based on the measuring data of the test river, the Hongje. the water quality of the test river is generally good comparing to other urban rivers in Seoul, because of the interception of sewer flow. But this system makes the river dry up for 3-4 months in winter. On the other hand, in rainy period the storm from the combined sewer system causes rapid increasing pollutants loads. In order to simulate the urban storm and water quality of the trest basin, the models such as SWMM, ILLUDAS, STORM, HEC-1 were applied and the results are compared in its applicability and accuracy aspects. All models discussed here have shown good results and it seems that SUMM is the most effective model in simulating both quantity and quality. Also, regression relations between the water quantity and quality were derived and their applicabilities were discussed. This regression model is a simple effective tool for estimating the pollutant loads in the rainy period, but if the amount of discharge is bigger than measuring range of raw data, the accuracy becomes poor. This model could be supplemented by expanding the range of collecting data and introducing the river characteristics. The HEC-1 would be anther effective model to simulate storm runoff of a river basin including urban area.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.3892-3901
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• 2021

The pressure drop of a moisture separator in a steam generator is the important design parameter to ensure the successful performance of a nuclear power plant. The moisture separators have a wide range of operating conditions based on the arrangement of them. The prediction of the pressure drop in a moisture separator is challenging due to the complexity of the multi-dimensional two-phase vortex flow. In this study, the moisture separator test facility using the air/water two-phase flow was used to predict the pressure drop of a moisture separator in a Korean OPR-1000 reactor. The prototypical steam/water two-phase flow conditions in a steam generator were simulated as air/water two-phase flow conditions by preserving the centrifugal force and vapor quality. A series of experiments were carried out to investigate the effect of hydraulic characteristics such as the quality and liquid mass flux on the two-phase pressure drop. A new prediction model based on the scaling law was suggested and validated experimentally using the full and half scale of separators. The suggested prediction model showed good agreement with the steam/water experimental results, and it can be extended to predict the steam/water two-phase pressure drop for moisture separators.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.59-65
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• 2011

The purpose of this study was to analyze the water quality change when wastewater applied to study paddy fields. CREAMS-PADDY (Chemical, Runoff and Erosion from Agricultural Management System) model was used to estimate the field-scale water quality. Simulated results were compared with observed data monitored from Byeongjeom study paddy fields which is located near the Suwon sewage treatment plant in Gyeonggi-do. Significance analysis was performed for the three different irrigation water quality level and five fertilizer reduction scenarios using LSD (Least Significant Difference) and DMRT (Duncan's Multiple Range Test). Total nitrogen was found to be significant for both irrigation water quality level and fertilizer reduction while total phosphorus was not. Annual drainage load for total nitrogen was reduced by 66~92 % compared to irrigation load when treated wastewater irrigated to study paddy fields from 2002 to 2007. Total phosphorus was reduced by 70~86 %.

• Journal of Environmental Science International
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• v.17 no.1
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• pp.113-118
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• 2008

[ $6{\sim}13mg/L$ ] base water concentration on monthly BOD has been kept at the Geukrak bridge point for this research target and it indicates the water quality under the existed rank. Due to this present condition of water quality, the demage of ecology from the upper stream to the lower one of the bridge could be conjectured. Moreover, nonstructural extinction of the ecology seems to have gotten worse between both the streams of Yeoungsan River. On this research, eco-corridor between the upper stream and the lower stream of the river should be ensured, the ecological demage needs to be cut off, a dispersed discharge method which the existed method of the 1st sewage plant in Gwangju was enhanced to should be inducted for the procuring of various water ecosystem, and the conditions by the scenario suggested from this research could be applied to a water quality model. then, analysis the improvement effect of the water quality adjacent the river. From the test result, Case3-Type1 scenario is thought to be the best one. From the test result with Case3-Type1 when the concentrated discharge was never done, 0.07 mg/L of BOD concentration was increased at the lower stream where Yeoungbon B point (Haksan Bridge) is but the water improvement effect of $0.24{\sim}2.87mg/L$ is thought to have been done at the area of water deterioration.

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.701-711
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• 2001

Forecasting of water quality variation is not an easy process due to the complicated nature of various water quality factors and their interrelationships. The objective of this study is to test the applicability of neural network models to the forecasting of the water quality at Gongju station in Geum River. This is done by forecasting monthly water qualities such as DO, BOD, and TN, and comparing with those obtained by ARIMA model. The neural network models of this study use BP(Back Propagation) algorithm for training. In order to improve the performance of the training, the models are tested in three different styles ; MANN model which uses the Moment-Adaptive learning rate method, LMNN model which uses the Levenberg-Marquardt method, and MNN model which separates the hidden layers for judgement factors from the hidden layers for water quality data. the results show that the forecasted water qualities are reasonably close to the observed data. And the MNN model shows the best results among the three models tested

• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.72-80
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• 1999

Separation of VOCs(Volatile Organic Compounds) in Water Using Activated Carbon is known to be effective. Activated Carbon has been and will be employed in many water treatment plants. Simplified plug flow homogeneous surface diffusion model(PFHSDM) has been used to predict adsorption of organic matter. Finite Element Method(FEM) was used to analyze the model. Out of water quality control substances, benzene, toluene and tetrachloroethylene were used in the small column test. Film diffusion coefficients and surface diffusion coefficients were obtained from the column test, and were compared with the modeling results. Mc Cune, Williamson, William and Kataoka model, were compared with film diffusion coefficients obtained in the test. McCune model was fitted best for those VOCs used in this experiment. Film diffusion coefficients of VOCs obtained were benzene 0.265 cm/min, toluene 0.348 cm/min and tetrachloroethylene 0.298 cm/min. Surface diffusion coefficients of VOCs obtained were benzene $6.36{\times}10^{-8}cm^2/min$, toluene $3.20{\times}10-8cm2/min$, and tetrachloruethylene $4.94{\times}10^{-8}cm^2/min$.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.391-393
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• 2006

In this study, the performance of artificial neural network (ANN) models for estimating spatial distribution of water quality was evaluated using electric conductivity (EC) values in landfill site. For the ANN model development, feedforward neural networks and backpropagation algorithm with gradient descent method were used. In Test 1, the interpolation ability of the ANN model was evaluated. Results of the ANN model were more precise than those of the Kriging model. In Test 2, spatial distributions of EC values were predicted using precipitation data. Results seemed to be reasonable, however, they showed a limitation of ANN models in extrapolations.

• Journal of Environmental Science International
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• v.21 no.8
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• pp.965-975
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• 2012

Loading of NPS pollutant was valued through simulation by using BASINS/HSPF model which can simulate runoff volume in rainfall by time. For the verification of the model, it was analyzed the scatter diagram of the simulation value and measure value of water quality and runoff volume in Dongcheon estuary. Using the built model, a study on the time-variant characteristics of runoff and water quality was simulated by being classified into four cases. The result showed the simulation value was nearly same as that of the measured runoff. In the result of fit level test for measured value and simulated value, correlation of runoff volume was computed high by average 0.86 and in the water quality items, fit level of simulation and measurements was high by BOD 0.82, T-N 0.85 and T-P 0.79.