• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.260-266
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• 2009

Non-revenue water reduction(NRW) technologies are implemented to evaluate and manage leakages scientifically in water distribution systems under local governments. A development of quantitative leakage indicator by measuring minimum night flow, pressure control policy by installation of PRV(pressure reducing valve) and the establishment of leakage prevention schemes by residual life modeling of deteriorated water pipes are reviewed and studied. Estimation models of allowable leakage are developed by measuring and analyzing minimum night flow at residential and commercial area in Nonsan city, which is suggested from UK water industry and can improve an existing leakage indicator for the evaluation of non-revenue water. Also, pressure control method is applied and analyzed to Uti distribution area in Sacheon city in the operation aspect. As results, $466\;m^3/day$ of leakage can be reduced and it is expected that 113million won of annual cost can be saved. In the part of corrosion velocity and residual life assessment, non-linear prediction models of residual thickness are proposed by assessment of corrosion velocity based on exposure years, soil and water quality etc., since the deteriorated water pipe play a major role to increase leakage. It is expected that collection data and analyzing results can be applied effectively and positively to reduce non-revenue water by accumulating surveying data and verifying the results in the business field of water distribution systems under local governments.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.15-22
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• 2010

Chloride-induced corrosion of steel bars in concrete exposed to marine environments has become one of the major causes of deterioration in many important facilities made of reinforced concrete. A study on chloride penetration in concrete has developed through long period exposure test along seawater, assesment of chloride ion diffusion by electrochemical techniques and so on. However, reasonable and exclusive chloride penetration model considering concrete material properties with mixture, degree of hydration, binding capacity has not been established. Therefore, in this paper, chloride penetration analysis of non-steady state is accomplished with material properties of concrete. Comparing with the results of analysis and chloride ponding test, we could accept the effect of binding capacity on chloride penetration in concrete and these results could be applied to a service life prediction of R.C. structures submerged in seawater. Therefore, there are 20~40% differences of service life to SHRP prediction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.66-74
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• 2016

The objective of this study is the investigation of the influence of carbonation on the penetration of chloride ions in reinforced concrete sections for different mix proportions and environmental conditions. A comprehensive numerical model based on the change of the pore structure and the chemical equilibrium was used for this combined action of carbonation and chloride ingress. The empirical formulae of some parameters in this model are estimated according to numerous experimental data. And, a set of data analysis is carried out to simplify the estimation of model variables to reduce the computational cost. A coupled simulation of the transports of carbon dioxide, chloride ions, heat and moisture is carried out. Then, the parametric analysis is given and the numerical results show that the effect of carbonation of the free chloride ingress is significant and depends on the binder types and concrete mix proportion.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.247-247
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• 2012

기후변화로 나타나게 될 댐 저수지의 수질 및 생태환경 변화에 대한 분석은 국가 수자원관리 측면에서 우선적으로 대비해야할 중요한 문제로써, 수자원을 안정적이고 효과적으로 관리 및 활용하기 위해서 기후변화로 인한 댐 저수지의 수환경 변화의 정확한 분석과 취약성 평가가 필수적이다. 이러한 기후변화로 인한 신뢰성 있는 영향평가를 위해서는 기후변화시나리오 분석, 댐 유역의 오염물질 유출을 시 공간적으로 해석할 수 있는 유역 모델과 댐저수지로 유입된 이후 오염물질 거동 분석을 위한 저수지 모델이 필요하며, 특히 다양한 기후변화 시나리오하에서의 미래 전망과 발생가능한 취약성을 예측 및 평가하는 기술을 필요로 한다. 본 연구에서는 총 7개의 다목적댐 유역과 저수지에 대하여 기후변화로 인한 신뢰성이 있는 영향평가를 위해서 기후변화 시나리오의 상세화를 통한 상세지역의 기후예측, 댐 유역 모형에서의 유출, 토사 및 오염물질예측과 저수지모형을 통한 미래의 저수지내 오염/영양물질순환 및 분포예측을 통해 기후변화에 의한 다목적댐 취약성을 평가하고자 한다. 총 7개의 다목적댐 유역의 기후변화 시나리오 적용에 따른 유출변화 및 하천수질 전망을 위해 인공신경망 방법에 의해 상세화된 기후자료를 검보정된 SWAT 모형에 적용하였다. 이때, 기준년에 해당하는 Baseline 기간은 인공신경망 학습기간(1990-2010)과 동일하게 모의하였으며, 미래 분석기간 역시 마찬가지로 2011-2040, 2041-2070, 2071-2100의 3개 기간으로 구분하였다. 또한, 미래 전망결과에 대한 분석은 각 30년 일별 모의결과에 대한 월 평균, 계절 평균으로 분석하였다. 유출변화 전망은 댐유역별 월별 총유입량 변화와 함께 유황분석을 통해 미래 댐유입량에 대한 규모 및 변동성 분석을 실시하였으며, 하천수질 변화 전망을 위해 호소유입 하천의 Sediment, TN, TP 월별 오염부하량 변화 분석을 실시하였다. 또한 댐유입 총량에 대한 변동성을 분석한 후, 저수지수질모델의 입력경계조건에 해당하는 각 댐저수지 유입 하천의 미래 유출량 및 수질농도 변화를 분석하였다.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.529-540
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• 2003

Recently, the researches on the durability design of concrete structures have been studied. As the examples, models to evaluate the service life prediction of the structure have been developed. The purpose of this article is to develop the model for predicting remaining service life. The final aim is to provide the user time for repairing the concrete structures. In addition, it makes possible to maintain the concrete structure economically. 70 reservoirs out of the inland concrete structures were selected and concrete structures of their components were surveyed. Two methods were used for measuring carbonation; TG/DTA method and Phenolphtalein indicator and, the value of pH was measured by the pH meter, After deriving correlations of calcium carbonate and used year, duration from completion year to 2002, pH value, and concrete cover depth the model was developed for predicting remaining service life by measuring data as small as possible. The conventional models had been developed on the basis of experiment data obtained from the restricted lab environment like as carbon gas exposure. On the other hand this model was developed on the basis of measuring data obtained from the real field that the complex deterioration actions are occurred such as freezing and thawing, carbonation, steel corrosion, and so on. The reliability of the developed model will be evaluated high in this point and this model can help to maintain concrete structures economically by providing the manager time to repair the deteriorated concrete structures in site of facility management.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.19-27
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• 2010

Aging and severe environments are major causes of damage in reinforced concrete (RC) structures such as buildings and bridges. Deterioration such as concrete cracks, corrosion of steel, and deformation of structural members can significantly degrade the structural performance and safety. Therefore, effective and easy-to-use methods are desired for repairing and strengthening such concrete structures. Various methods for strengthening and rehabilitation of RC structures have been developed in the past several decades. Recently, FRP composite materials have emerged as a cost-effective alternative to the conventional materials for repairing, strengthening, and retrofitting deteriorating/deficient concrete structures, by externally bonding FRP laminates to concrete structural members. The main purpose of this study is to investigate the effectiveness of adaptive neuro-fuzzy inference system (ANFIS) in predicting behavior of circular type concrete column retrofitted with FRP. To construct training and testing dataset, experiment results for the specimens which have different retrofit profile are used. Retrofit ratio, strength of existing concrete, thickness, number of layer, stiffness, ultimate strength of fiber and size of specimens are selected as input parameters to predict strength, strain, and stiffness of post-yielding modulus. These proposed ANFIS models show reliable increased accuracy in predicting constitutive properties of concrete retrofitted by FRP, compared to the constitutive models suggested by other researchers.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.338-346
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• 2013

The conventional lead acid battery is optimized for cranking performance of engine. Recently electric devices and fuel economy technologies of battery have influenced more deep cycle of dynamic behavior of battery. I also causes to reduce battery life-time. This study proposed that aging battery model is focused for increasing of battery durability. The stress factors of battery aging consist of discharge rate, charging time, full charging time and temperature. This paper considers the electrochemical kinetics, the ionic species conservation, and electrode porosity. For prediction of battery life cycle we consider battery model containing strong impacts, corrosion of positive grid and shedding. Finally, we validated that modeling results were compared with the accelerated thermal measurement data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.11-17
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• 2011

A major source of durability problems in concrete structures is the corrosion of steel by the damage of passivity layer around steel bars. As chloride ion penetration is major cause of the destruction of passivity layer, evaluation of depth and concentration profile of chloride ion is the essential factor for the service-life estimation of concrete structure. To estimate chloride ion penetration characteristics, this paper on the basis of in-situ experimental data investigated the depth and concentration profile of chloride ion penetration. The core specimens are obtained at air-zone, splash zone, and tidal zone in Wando, Masan, Incheon, Gwangyang, and donghae harbors. Colorimentric method measured the chloride ion penetration depth and ASTM C 114 evaluated the concentration profile of chloride ion. Based on experimental data, the influence of harbor location and exposure condition on chloride ion penetration is evaluated.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1530-1535
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• 2008

수자원과 관련된 많은 분쟁 및 갈등들은 국내뿐만 아니라 전 세계적으로 발생하고 있다. 따라서 분쟁 및 갈등해결을 위한 많은 연구들이 진행되고 있지만 수자원과 관련된 분쟁들은 대부분 원활한 해결을 이루지 못하고 있으며, 특히 국내의 경우에는 더욱 심각하다 할 수 있다. 따라서 제한된 자원인 수자원을 둘러싸고 수자원분쟁이 일어나는 것은 당연한 일이라 할 수 있으며, 분쟁의 양상도 다양하다. 댐 건설로 인한 상류지역과 하류지역의 갈등, 수로의 건설로 인해 수자원을 빼앗기는 지역과 수자원을 얻게 되는 지역 간의 갈등, 새로운 공단이나 개발로 인하여 하류지역에서 수질악화를 우려하여 반대하는 경우 등 여러 종류의 수자원으로 인한 분쟁이 있다. 수자원을 둘러싼 갈등이 쉽게 해결이 되지 않고, 또한 갈등 및 분쟁이 쉽게 발생되는 이유도 주체자들간 입장 차이에서 오는 성격이라 할 수 있겠다. 수자원과 관련된 분쟁에서 오는 여러 가지 갈등들은 사회적으로 많은 문제들을 발생시켜 수자원의 원활한 공급이 저해될 수 있다. 이로 인해 사회적으로 수자원과 관련된 분쟁 해결에 들어가는 많은 시간과 노력, 비용을 생각해 볼 때, 효과적인 갈등 및 분쟁의 해결은 국가적 발전에 있어서 영향을 줄 수 있다. 그러므로 갈등 및 분쟁의 원활한 해결이 국가적 발전에 많은 비중을 차지 한다고 할 수 있다는 것은 이런 이유들 때문이라 할 수 있다. 본 연구에서는 국내 수자원과 관련된 분쟁사례들을 하천의 기능에 따른 분류, 발생 원인에 따른 분류, 분쟁주체에 따른 분류 등을 유형별로 구분하여 수자원분쟁의 여러 가지 사례들을 조사하였다. 또한 분쟁 및 갈등을 해결하기 위한 방안으로 거버넌스 시스템을 적용하였고 분쟁의 원활한 합의 조정방안 및 문제점을 제시하기 위한 외국의 시민참여 모델을 특징 및 특성을 분석하였다. 또한, 공영시각모형, 게임이론, 제도설계이론의 공학적 모형을 바탕으로 물분쟁의 해결을 위한 대안을 모색할 수 있는 과학적 접근 방안을 제시하여 향후 여러 가지형태의 국책사업 시행 시 발생 할 수 있는 분쟁의 해결 및 조정을 위한 방안으로 활용할 수 있는 토대를 마련하고자 한다.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.23-27
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• 1998

To protect the underground pipeline from the mechanical damage and to enhance the cathodic protection effect, the river sand has been backfilled traditionally around the buried pipeline. However, river sand became depleted and expensive. One has to seek for the economic alternative materials. Crashed stone is a good candidate for the backfill material. In this study, how much the particle size and shape of the crashed stone can effect on the gas pipeline coating was examined. A series of laboratory and field test was performed. In the Lab, the increasing loads were applied to the coated pipeline surrounded by the crashed stone, where no significant damage was observed.