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Featured researches published by Juhwan Kim.


Pipelines 2007: Advances and Experiences with Trenchless Pipeline Projects | 2007

Trenchless Water Pipe Condition Assessment Using Artificial Neural Network

Zong Woo Geem; Chung-Li Tseng; Juhwan Kim; Cheolho Bae

In order to assess the water pipe condition without excavating, artificial neural network (ANN) model was developed and applied to real-world case in South Korea. For the input in this ANN model, 11 factors such as (1) pipe material, (2) diameter, (3) pressure head, (4) inner coating, (5) outer coating, (6) electric recharge, (7) bedding condition, (8) age, (9) trench depth, (10) soil condition, and (11) number of road lanes were used; and, for the output, overall pipe condition index was derived based on 5 factors such as (1) outer corrosion, (2) crack, (3) pin hole, (4) inner corrosion, and (5) H-W C value. For the ANN computing, each factor was normalized into the range of 0 to 1. The ANN model could find better results than those of multiple regression model in terms of statistical correlation between observed and computed data.


Pipelines 2007: Advances and Experiences with Trenchless Pipeline Projects | 2007

Assessment of Residual Tensile Strength on Cast Iron Pipes

Juhwan Kim; Cheol-Ho Bae; Hyungmin Woo; Jeong-Hyun Kim; Seong-Ho Hong

Criteria for rehabilitation priority are an important factor in planning the improvement of water supply systems. In this study, deteriorations of water pipes are discussed to evaluate structural stability of deteriorated cast iron transport and transmission pipes. For the purposes, safety factor is introduced and estimated by measuring tensile strength and analyzing stress caused by the internal-external loads working on buried pipe body. Prediction models of a residual tensile strength are presented using pit characteristics and fracture toughness. Related information is surveyed and collected in the fields up the pipe by digging and assessing its structural stability. The collected data is analyzed to evaluate the deterioration degree of the pipes including corrosion and pitting characteristics, fracture toughness, installation environment and water qualities etc. Assessment models developed in this study showed a little correlation for measured residual tensile strength. The results will very help water utilities to manage water pipes in the aspect of rehabilitation and assessment of structural safety.


Urban Water Journal | 2015

Pressure measurements with valve-induced transient flow in water pipelines

Doo Yong Choi; Juhwan Kim; Doo-Jin Lee; Dohwan Kim

Pressure measurements provide valuable insights for managing water supply systems by tracking time-dependent hydraulic transients. In this study, we report on two pressure-monitoring issues – sampling location and sampling interval – by analyzing a valve-induced transient event that was not recorded in the 1-min timestamp pressure generated by the existing supervisory control and data acquisition (SCADA) system of a real water transmission line in the southern part of Korea. Field measurement data show that the measured pressure magnitude is influenced by the sampling location, which depends on pipe connectivity and distance from automatic control valve, and by the sampling interval, which is sensitive to network size for wave propagation. Based on the findings of the field experiments, a pressure-measurement method is proposed by employing numerical transient simulation and spectral analysis of pressure waves.


Journal of Korea Water Resources Association | 2013

A Study on the Method of Energy Evaluation in Water Supply Networks

Seong-Won Kim; Dohwan Kim; Doo Yong Choi; Juhwan Kim

The systematic analysis and evaluation of required energy in the processes of drinking water production and supply have attracted considerable interest considering the need to overcome electricity shortage and control greenhouse gas emissions. On the basis of a review of existing research results, a practical method is developed in this study for evaluating energy in water supply networks. The proposed method can be applied to real water supply systems. A model based on the proposed method is developed by combining the hydraulic analysis results that are obtained using the EPANET2 software with a mathematical energy model on the MATLAB platform. It is suggested that performance indicators can evaluate the inherent efficiency of water supply facilities as well as their operational efficiency depending on the pipeline layout, pipe condition, and leakage level. The developed model is validated by applying it to virtual and real water supply systems. It is expected that the management of electric power demand on the peak time of water supply and the planning of an energy-efficient water supply system can be effectively achieved by the optimal management of energy by the proposed method in this study.


Journal of Korea Water Resources Association | 2013

Leakage Detection of Water Distribution System using Adaptive Kalman Filter

Seong-Won Kim; Doo Yong Choi; Cheol-Ho Bae; Juhwan Kim

Leakage in water distribution system causes social and economic losses by direct water loss into the ground, and additional energy demand for water supply. This research suggests a leak detection model of using adaptive Kalman filtering on real-time data of pipe flow. The proposed model takes into account hourly and daily variations of water demand. In addition, the model`s prediction accuracy is improved by automatically calibrating the covariance of noise through innovation sequence. The adaptive Kalman filtering shows more accurate result than the existing Kalman method for virtual sine flow data. Then, the model is applied to data from two real district metered area in JE city. It is expected that the proposed model can be an effective tool for operating water supply system through detecting burst leakage and abnormal water usage.


12th Annual Conference on Water Distribution Systems Analysis (WDSA) | 2011

STATISTICAL ESTIMATION MODEL OF WATER PIPE DETERIORATION BY MATHEMATICAL FUNCTION

Juhwan Kim; Cheol-Ho Bae; Doo-Jin Lee; Dooyoung Choi

Service life of water pipes buried in the underground is considerably affected from various factors such as environmental characteristics, pipe characteristics, operation and maintenance, etc. Therefore it is difficult to determine their service life as uniformly the same value assigned by related laws and ordinances. As a result, the service life should be determined by the technical judge based on the assessment for the condition of water pipes. In this study, It was established that the methodology could predict present and future failure risk, and plan short and long-term strategies for replacement/rehabilitation through the assessment for the physical deterioration and economical values of buried water pipe. The methodology was applied for the verification and reliability to several sites selected in multi-regional transmission pipelines. In conclusion, the proposed method could helps to support reasonable and economical decision of rehabilitation/replacement in the present and future. To improve conventional assessment method of aged water pipes, affecting factors are simplified based on the statistical analysis results from the measured data in the field and the physical deterioration mechanism for better reliability. Also, the guide-line is developed to carry out the reasonable rehabilitation planning through water pipe condition assessment.


한국지능시스템학회 국제학술대회 발표논문집 | 2007

Evaluation of Deteriorated Water Pipes by Fuzzy Logics

Juhwan Kim; Cheol-Ho Bae; Sang-Young Park


Journal of Korean Society of Water and Wastewater | 2014

The assessment of self cleaning velocity and optimal flushing velocity in water distribution system

Cheol-Ho Bae; Doo Yong Choi; Juhwan Kim; Do-Hwan Kim


Eighth Annual Water Distribution Systems Analysis Symposium (WDSA) | 2008

Evaluation Models of Deteriorated Water Mains for Replacement/Rehabilitation by Field Surveying

Juhwan Kim; Cheoulho Bae; Jeonghyun Kim


WDSA 2012: 14th Water Distribution Systems Analysis Conference, 24-27 September 2012 in Adelaide, South Australia | 2012

Develpment of water demand forecasting simulator and its performance assessment

Juhwan Kim; Gangwook Shin; Dooyong Choi

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Do-Hwan Kim

Sungkyunkwan University

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Chung-Li Tseng

University of New South Wales

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