• Geomechanics and Engineering
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• 제37권1호
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• pp.65-72
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• 2024

Water ingress poses a common and intricate geological hazard with profound implications for tunnel construction's speed and safety. The project's success hinges significantly on the precision of estimating water inflow during excavation, a critical factor in early-stage decision-making during conception and design. This article introduces an optimized model employing the gene expression programming (GEP) approach to forecast tunnel water inflow. The GEP model was refined by developing an equation that best aligns with predictive outcomes. The equation's outputs were compared with measured data and assessed against practical scenarios to validate its potential applicability in calculating tunnel water input. The optimized GEP model excelled in forecasting tunnel water inflow, outperforming alternative machine learning algorithms like SVR, GPR, DT, and KNN. This positions the GEP model as a leading choice for accurate and superior predictions. A state-of-the-art machine learning-based graphical user interface (GUI) was innovatively crafted for predicting and visualizing tunnel water inflow. This cutting-edge tool leverages ML algorithms, marking a substantial advancement in tunneling prediction technologies, providing accuracy and accessibility in water inflow projections.

• Journal of Advanced Marine Engineering and Technology
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• 제38권3호
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• pp.276-284
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• 2014

본 연구의 목적은 ORC(Organic Rankine Cycle) 반경류터빈의 설계기법을 확립하는 것이다. 이를 위하여 반경류터빈의 예비설계프로그램인 RTDM(Radial Turbine Design Modeler) Ver.2.1를 개발하였다. RTDM Ver.2.1의 정확성을 검증하기 위해 R32를 이용한 200kW급 OTEC(Ocean Thermal Energy Conversion)용 반경류터빈을 설계하였고 이에 대해 CFD(Computational Fluid Dynamics) 수치해석을 수행하였다. 그 결과 RTDM Ver.2.1의 정확성은 설계한 반경류터빈의 전엔탈피 강하를 기준하여 약 94.6%로 나타났다. 본 연구에서는 반경류터빈의 설계요구조건인 출력조건과 로터출구조건을 충족시키기 위해 질량유량조정 방법을 도입하였다. 이에 따라 RTDM Ver.2.1을 이용하여 설계한 200kW급 OTEC용 반경류터빈의 질량유량은 21.2kg/s이며 이 때 Total to Total과 Total to Static 효율은 각각 89.8%, 85.3%이다.

• 상하수도학회지
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• 제20권1호
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• pp.53-62
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• 2006

This study was carried out to obtain quantities of infiltration, inflow and exfiltration on sewer pipes of three areas at a small city. From the results, the most investigated sewer pipes should be infiltrated by underground water and undetermined water. Flowrate commonly showed two peak at 6 to 8 a.m. and 6 to 9 p.m. and which may be influenced by the sewer flowrate with washing or bathing time. BOD/TN ratio of below 4.0 were inferior as compared with proper criteria 5.1. Infiltration/inflow rates of three areas were 21.7% and $0.08m^3/km$ of A, 12.4% and $0.015m^3/km$ of B, 22.4% and $0.021m^3/km$ of C, respectively. This indicates that infiltration/inflow rate of A was obviously greater than that of B and C. Also, these results show that we can conduct sewer maintenance in good order as A, C and B zone.

• 물과 미래
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• 제18권4호
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• pp.347-359
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• 1985

본 연구는 단일다목적 저수지의 운영정책을 수립함에 있어서, DP를 적용하여 댐의 여러 물리적 제약조건하에서 댐 하류의 용수수요를 최대로 충족시킬 수 있는 월별 저수지 최대 운영정책을 수립하는 알고리즘을 개발하는데 주안점을 두었다. 분석대상인 안동댐의 과거 월평균 유입량으로부터 장래 월유입량을 모의발생시키고, 그 모의 발생된 자료 중에서 ddlqfid 계열 A, B, C를 선정하여, 각 계열별로 낙동강 본류의 용수수요 중에서 안동댐이 30%∼100%까지 충족시킬 수 있도록 8개의 대안을 설정하였다. 그리고 DP 모델을 적용시켜 물 수요량과 운영곡선에 근거한 시스템 운영목적함수를 가장 잘 수행하는 대안을 최적 운영 정책으로 결정하였다.

• 한국환경과학회지
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• 제17권4호
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• pp.451-459
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• 2008

This study was carried out forecasting of pollution inflow of the Small Mountainous Catchment, namely; Seolma-cheon experimental catchment. Pollutographs of DO, BOD, T-N, Conductivity, T-p, pH. COD, SS from this catchment were obtained from in-situ data of total ten events using QUAL2E-PULS model. From the analysis results, between up stream(Sabang-bridge) and down stream (Memorial-bridge, outlet) obtained relation formula of water quality component. Determination coefficient of relation formula, Conductivity, COD, BOD, DO, pH, T-N, T-P, and SS showed high relation of $0.87{\sim}0.99$. The increases of DO, BOD, COD, and pH concentration of Memorial-bridge were associated with pollution inflow by road building far 2.25km from Sabang-bridge to down stream. The analysis results of QUAL2E-PULS simulation and up/down stream relation formula, pollution amounts of DO, BOD, COD and pH increased at Memorial-bridge and pollution source site. Therefore, pollution inflow can be forecasted exactly by up/down stream relation formula at pollution source site.

• Wind and Structures
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• 제30권6호
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• pp.597-616
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• 2020

The blockage effect on the aerodynamic characteristics of tall buildings is a fundamental issue in wind tunnel test but has rarely been addressed. To evaluate the blockage effects on the aerodynamic forces on a square tall building and flow field peripherally, large eddy simulations (LES) were performed on a 3D square cylinder with an aspect ratio of 6:1 under the uniform smooth inflow and turbulent atmospheric boundary layer (ABL) inflow generated by the narrowband synthesis random flow generator (NSRFG). First, a basic case at a blockage ratio (BR) of 0.8% was conducted to validate the adopted numerical methodology. Subsequently, simulations were systematically performed at 6 different BRs. The simulation results were compared in detail to illustrate the differences induced by the blockage, and the mechanism of the blockage effects under turbulent inflow was emphatically analysed. The results reveal that the pressure coefficients, the aerodynamic forces, and the Strouhal number increase monotonically with BRs. Additionally, the increase of BR leads to more coherence of the turbulent structures and the higher intensity of the vortices in the vicinity of the building. Moreover, the blockage effects on the aerodynamic forces and flow field are more significant under smooth inflow than those under turbulent inflow.

• Tribology and Lubricants
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• 제25권2호
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• pp.120-124
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• 2009

In automobile chassis system, several environmental factors weaken durability of automobile's components. The environmental factors are temperature, humidity, intensity of radiation and dust particle inflow. Especially, dust particle inflow leads to increase in friction and wear of automobile's components. The wear of automobile's component leads to increase in noise and exerts a bad influence on life of components. In this study, dust particles were investigated for study on the influence of dust particle inflow. Dust particles are collected on urban area, rural area and highway in China. The size of dust particle is analyzed using the image plus program, and the element of dust particle is analyzed using the SEM and EDX. The elements of dust particle are $SiO_2$ and $Al_{2}O_{3}$. The other elements(Na, Ca, Cl etc..) are detected on urban area and highway.

• 한국환경과학회지
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• 제22권8호
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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.

• 상하수도학회지
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• 제28권1호
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• pp.33-45
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• 2014

In this study, current sewer infiltration/Inflow(I/I) computation and application method was examined about improvement and adequacy relating to the main issues raised by the field for practitioners. The results of review about infiltration calculation method were considered to be in need of improvement at 'standards of minimum sewage calculation'. Furthermore, the results of review about I/I application method were considered to be in need of improvement at 'standards of seasonal infiltration application' and 'the relative decrease in the Annual evaluation standards'. In addition, annual I/I analysis at JC County for the four years(2009~2012) in respect of operation flow and rainfall data was conducted. The result of annual infiltration analysis, compared average daily sewage generated average infiltration rate was found in 21.95 %, infiltration by unit was found in $0.31m^3/day/cm/km$ and $0.12m^3/day/day$, respectively. The result of annual inflow analysis, average rainfall - Inflow equations was found $y=5.499{\times}$($R^2$ 0.793), and the average Inflow quantity by sewer extension was predicted to $0.66m^3/mm-km$.

• 한국수산과학회지
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• 제30권6호
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• pp.1033-1043
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• 1997

In order to understand the generation mechanism of the Ulleung Eddy, we carried out a series of numerical experiments using the nonlinear 11/2 - layer model allowing the inflow of the Tsushima Current. According to our numerical results, the Ulleung Eddy was generated due to the inflow variations of the Tsushima Current. Its inflow through the Korea Strait was deflected to the east due to the Coriolis force and the nonlinear self advection. Thus, an anticyclonic motion was formed at the north of the Korea Strait. The inflow became a coastal boundary current, and finally flowed out model ocean through the eastern exit. When the speed of inflow decreased slowly, the eddy- like motion at the north of the Korea Strait changed into an enclosed anticyclonic eddy of about 200 km in diameter. The Ulleung Eddy became circular shape due to the nonlinear self advection, then changed into elliptical shape in meridional direction because of the blocking effect of the western boundary.