• IE interfaces
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• v.10 no.3
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• pp.125-132
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• 1997

We proposed a 2-step neural network approach for estimating machining parameters of electric discharge wire cut. The first step net, which is described as a backward neuro-estimation, is designed for estimating coarse cutting parameters while the second phase net, as a polishing forward neuro-estimation, is utilized for determining fine parameters. Sequential estimation procedure, based on backward and forward net, is performed using the net's approximation capability which is M to 1 and 1 to M mapping property. Experimental results an given to evaluate the accuracy of the proposed 2-step neuro-estimation.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.373-382
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• 2007

In the vertical drain method, discharge capacity is generally one of the most important factor which affect on the estimation of the drain efficiency. However, adopting the drain considering discharge capacity only is not sufficiently considered method so that systematic criteria for adoption is necessary to choose the most suitable drain. Therefore, this study represents the application method considering behavior of the ground and vertical drain which is coupled together and ground improvement efficiency analyzing various cases of discharge capacity test performed in the recent soft ground improvement projects. According to the analysis, most drains tend to satisfy the required discharge capacity. It presents that deformed shape of the drains and well resistance estimation along the ground settlement, improvement efficiency by water content ratio along the depth and shear strength obtained after ground improvement should be considered altogether with the discharge capacity to select the proper drain. Also, appropriate adoption of drain material considering the ground condition is vital through analyzing the field measured data and comparing the result of the discharge capacity test as various vertical drain materials are being constructed continuously.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.152-152
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• 2019

This study demonstrates a novel approach of remotely sensed estimates of stream flow at fifteen hydrological station in the Han River Basin, Korea. Multi-temporal data of the European Space Agency's Sentinel-1 SAR satellite from 19 January, 2015 to 25 August, 2018 is used to develop and validate the flow estimation model for each station. The flow estimation model is based on a power law relationship established between the remotely sensed surface area of water at a selected reach of the stream and the observed discharge. The satellite images were pre-processed for thermal noise, radiometric, speckle and terrain correction. The difference in SAR image brightness caused by the differences in SAR satellite look angle and atmospheric condition are corrected using the histogram matching technique. Selective area filtering is applied to identify the extent of the selected stream reach where the change in water surface area is highly sensitive to the change in stream discharge. Following this, an iterative procedure called the Optimum Threshold Classification Algorithm (OTC) is applied to the multi-temporal selective areas to extract a series of water surface areas. It is observed that the extracted water surface area and the stream discharge are related by the power law equation. A strong correlation coefficient ranging from 0.68 to 0.98 (mean=0.89) was observed for thirteen hydrological stations, while at two stations the relationship was highly affected by the hydraulic structures such as dam. It is further identified that the availability of remotely sensed data for a range of discharge conditions and the geometric properties of the selected stream reach such as the stream width and side slope influence the accuracy of the flow estimation model.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.452-457
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• 2008

Nonpoint source (NPS) pollution is caused by rainfall moving over and through the ground. As the runoff moves, it picks up and carries away various pollutants from NPS. The discharge pattern of NPS pollutant loads is affected by the distribution of the rainfall during the year. This study analysed relationship between the rainfall event and the stream flow rate, and estimated the rainfall discharge ratio on the specific design flow which can be used as nonpoint discharge coefficient for the estimation of NPS pollution load. It is considered that nonpoint discharge coefficient can be effectively used for the calculation of NPS pollution load at the time of water quality modelling for the management of Total maximum daily load (TMDL).

• Journal of Environmental Science International
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• v.6 no.5
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• pp.417-423
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• 1997

The objective of this study Is to supply basic data for large reservoir sedimentation research In future and make suggestions to maintain and opera능 the reservoir more of efficiently. At first, previous studios about the estimation of sediment yield rate were reviewed in Korea. And the discharge rating curves of upstream stage gauging stations and the correlation between dam Inflow and stage discharge were analyzed. With the analysis results, the spec유c sediment rate of Soyanggang dam was estimated as 608 m3/km2/yr. It was similar to that of Soyanggang dam feasibility study and 1994's field surveys of the reservoir than that of 1983's field surveys. Because the sediment rating curves were derived under the low discharge conditions, It needs to be checked under the flood conditions. However, the suggested methods such as flowrate analysis and sediment estimation will be useful to the sediment studios In future. Key words . reservoir sediment, sediment yield rate, rating curve, flowrate analysis.

• Journal of Power System Engineering
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• v.14 no.1
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• pp.27-33
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• 2010

We investigate some operation characteristics and energy efficiency of the BLDC motor system driven by different two types power conversion method depends on same battery source for applying to electrical motor propulsion system of a small ship. Also, we suggest an estimation manner of operating performances such as total running distance and operating speed of ships from basic discharge voltage characteristics of batteries. Through some experiments, direct power conversion was better than indirect method on the view point of energy efficiency and the voltage discharge characteristics could be used as important design factor for estimating operating performances of small ships driven by electrical motors.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.1
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• pp.27-38
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• 2006

In this study, we developed a program to estimate discharge efficiently considering major hydraulic characteristic including water level, river bed, water slope and roughness coefficient in a natural river. Stream discharge was measured at Gongju gauge station located in the down stream of the Daechung Dam during normal and dry seasons from 2003 to 2004. The developed model was compared with the results from the existing rating curve at T/M gage stations, and was used for runoff analyses. Evaluating the developed river discharge estimation program, it was applied during 1983-2004 that base flow separation method and RRFS (Rainfall Runoff Forecasting System) which is based on SSARR (Streamflow Synthesis And Resevoir Regulation). The result presents the stage-discharge curve creator range at the Gong-ju is overestimated by approximately $10-20\%$, especially at the low stage. It is attributed to the hydraulic characteristics at the study. The discharge simulated by the RRFS and base flow separation, which is calibrated using the measurement at the early spring and late fall season during relatively d]v season, shows the least errors. The coefficient of roughness at Gongju station varied with the high and low water level.

• Journal of Environmental Science International
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• v.24 no.4
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• pp.425-435
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• 2015

A number of projects for development have been done continuously due to the increase of tourist in Jeju Island. However flood disaster countermeasure due to urbanization is not considered during this development projects. This study is to make basic process for the flood estimation in Han stream of Jeju Island. The variation of stream discharge due the every 5 years' land use change from 1980 to 2005. Data for flood events (rainfall and discharge) were collected for HEC-HMS model. Clark method was used for unit hydrograph analysis. For the estimation of Clark unit hydrograph parameters, Kraven II and Sabol's empirical equations were applied. The peak discharge increased 9.9~33.67% and total discharge amount increased 12.53~30.21%. Also, time of concentration for peak discharge was reduced by 10 minutes for each event.

• Proceedings of the KGS Conference
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• 2005.05a
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• pp.95-96
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• 2005

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.468-470
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• 1997

This paper presents an estimation method of the number of partial discharge(PD) sources and their locations in power transformer. To identify multiple PD sources and their locations, the directions-of-arrival estimation algorithm is employed. The results of simulations shows that the proposed method could be accurately detect the number of PD sources and their locations in power transformer.