• Computers and Concrete
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• v.16 no.3
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• pp.449-466
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• 2015

This paper aims to study the local bond stress-slip behavior of reinforcing bars embedded in lightweight aggregate concrete (LWAC). The experimental variables of the local bond stress-slip tests include concrete strength (20, 40 and 60 MPa), deformed steel bar size (#4, #6 and #8) and coarse aggregate (normal weight aggregate, reservoir sludge lightweight aggregate and waterworks sludge lightweight aggregate). The test results show that the ultimate bond strength increased with the increase of concrete compressive strength. Moreover, the larger the rib height to the diameter ratio ($h/d_b$) of the deformed steel bars is, the greater the ultimate bond stress is. In addition, the suggestion value of the CEB-FIP Model Code to the LWAC specimen's ultimate bond stress is more conservative than that of the normal weight concrete.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.2
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• pp.53-61
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• 2017

How to manage manhole is to estimate the part without observation and maintain the sewer. To get the information about current flow rate, visiting and measuring specific manhole is positively necessary. Also, there are some problems that accurate measurement of flow rate is difficult and obtaining the information about real-time whole flow rate is impossible. This thesis will easily grasp the accurate location and type of manhole to solve the problems, and provide the manhole system conveying information through direct radio communication with a manhole cover to renewal information of manhole properly. Besides, it intends to save the information about management of waterworks, maintenance of facilities, data for flow rate, and structure of manhole. Using these, it is supposed to offer how to handle manhole. Thus, this thesis delivers the information to manhole and into central servers directly without wire and provides the system and management method for effective maintenance of manhole.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.396-397
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• 2007

광역상수도 사업장에서 전력기기의 소손등으로 발생한 전기사고로 인해 안전사고, 용수공급 중단 등의 위험이 증가하고 있어, 용수공급 시설의 안정적 운영 및 전기 사고시 시설운영의 신뢰성을 확보하기 위해 인입 배전선로 이중화, 특고압 수전설비 이중화 및 전동기기동반 모선분할 등을 실시하여, 유지보수 및 운영신뢰도 향상을 위한 광역상수도 전력설비 안전성 확보를 기하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.484-490
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• 2012

광역상수도는 지난 40년 동안 우리나라의 경제성장에 지대한 역할을 수행하여 왔을 뿐만 아니라 안정적이고 깨끗한 물을 공급함으로써 국민복지에도 많은 기여를 하여 왔다. 그러나 광역상수도가 국민경제에 미치는 효과에 대한 계량적인 연구가 부족하여 광역상수도의 중요성이 상대적으로 소홀하게 여겨지고 있는 실정이다. 이에 본 연구는 광역상수도 사업의 파급효과를 분석하기 위해 산업과 산업간의 상관관계를 계량적으로 파악할 수 있는 분석인 산업연관분석을 수행하였다. 일반적으로 산업연관분석은 특정 시점에서의 국민경제를 반영하기 때문에 시계열적으로 분석하기가 매우 힘들다. 그러나 최근 한국은행에서는 2005년 이후 2009년까지의 각 년도별 산업연관표를 발표하고 있어 시계열적으로 광역상수도사업의 파급효과를 분석할 수 있게 되었다. 따라서, 본 연구에서는 기존의 수요유도형 모형뿐만 아니라 공급유도형 모형을 적용하여 2005년부터 2009년까지 산업연관분석을 수행하여 광역상수도사업의 파급효과 추이를 살펴봄으로써 광역상수도의 높은 경제적 타당성 및 국민경제적 파급효과를 검증하였다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.358-365
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• 2006

In this study, fragility curves of continuous buried pipelines subjected to transverse PGD (permanent ground deformation) due to liquefaction are proposed. For the waterworks system, continuos buried pipelines made of ductile iron, poly ethylene, and poly vinyl chloride are analyzed and fragility curves are drawn. Fragility curves are based on the repetitive analyses results and formulated with the dominant factors of behaviour of buried pipeline. With the use of fragility curves, engineers can estimate the status of damage of buried pipeline without overall knowledge of relevant features. Especially, fragility curves proposed in this study will act as a major module of earthquake loss estimation method. Moreover, critical value of magnitude and width of transverse PGD (by which the full damage status of buried pipelines are induced) are estimated. With the use of regression curves of these values, pre evaluation of seismic safety of buried pipelines located within liquefaction hazardous region will be possible.

• Journal of information and communication convergence engineering
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• v.16 no.4
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• pp.242-247
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• 2018

The data of K-Water waterworks is collected from various sensors and used as basic data for the operation and analysis of various devices. In this way, the importance of the sensor data is very high, but it contains misleading data due to the characteristics of the sensor in the external environment. However, the cleansing method for the missing data is concentrated on the prediction of the missing data, so the research on the detection and prediction method of the missing data is poor. This is a study to detect wrong data by converting collected data into quintiles and patterning them. It is confirmed that the accuracy of detecting false data intentionally generated from real data is higher than that of the conventional method in all cases. Future research we will prove the proposed system's efficiency and accuracy in various environments.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1099-1107
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• 2005

The purpose of this study was to find the transformation of organic matter as well as chlorine by product formation potential with ozone dosage. The removal percents of $UV_{254}$ and DOC were $23%{\sim}65%$ and $2%{\sim}15%$ and THMFP and HAAFP were $17%{\sim}52%$ and $9%{\sim}29%$ respectively at $0.5{\sim}3\;mgO_3/mgDOC$ ozone dosage. The hydrophobic and transphobic organic matter were reduced to $37%{\sim}68%$ and $35%{\sim}64%$, on the other hand the hydrophilir organic matter was increased to $40%{\sim}49%$ at $0.5{\sim}3\;mgO_3/mgDOC$ ozone dosage. The produced THMFP and HAAFP from the hydrophobic and transphilic organic matter were decreased greatly with increasing ozone dosage but these by products were increased in the hydrophilic matter. The produced THMFP and HAAFP per unit DOC were decreased and reactivity was reduced greatly with increasing crone dosage. The removal rate of THMFP per unit DOC was much higher than HAAFP by ozone treatment. The Br-THMFP per unit DOC was much more removed than chloroformFP per unit DOC with increasing ozone dosage. and The removal rate of TCAAFP per unit DOC was increased with increasing ozone dosage but TCAAFP was not affected by ozone treatment. Br-HAAFP was decreased at $1\;mgO_3/mgDOC$ ozone dosage but was not more removed above $1\;mgO_3/mgDOC$ ozone dosage. Br-HAAFP had lower removal effect than Br-THMFP by ozone treatment. The optimal ozone dosage can be determined about $1\;mgO_3/mgDOC$ by considering both disinfection by product formation and economical efficiency.

• Clean Technology
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• v.18 no.3
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• pp.272-279
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• 2012

In this study, an environmental-friendly cleaning agent utilizing organic acids and various additives has been developed and applied to the field for removal of scale deposited on the cleaning beds or distribution reservoirs of the waterworks. As an analytical result of scale on the cleaning beds, we found that it consists of mainly metallic oxides such as $SiO_2$, $Al_2O_3$, $Fe_2O_3$, and MnO. Malic acid, malonic acid, and citric acid showed relatively better solvency on $Al_2O_3$, $Fe_2O_3$, and MnO except $SiO_2$ among various organic acids. Mixed organic acid solutions of malic acid, malonic acid, and citric acid were prepared with certain weight ratios and their solvencies on mixed metal oxides of $Al_2O_3$, $Fe_2O_3$, and MnO were investigated. The experimental results showed that an 10% mixed organic acid solution prepared with weight ratio of malic acid : malonic acid : citric acid = 6 : 2 : 2 were found to have best scale solvency power of about 29%. The formulated cleaning agents with a small amount of nonionic surfactant showed much better solvency on mixed oxides than mixed organic solution alone. Especially, the formulated cleaning agent with 0.2 wt% LA-7 surfactant appeared to have best scale removal efficiency of about 35%. However, the formulated cleaning agent with disinfectants such as NaClO, $H_2O_2$ and $Ca(ClO)_2$ showed poor solvency on mixed oxides. It is inferred that surfactants are able to improve scale removal efficiency due to their capability of emulsification, and disinfectants cause to degrade scale solvency in water because of their oxidation. Based on these basic experimental results, formulated cleaning agents have been prepared with mixed organic acid solution, nonionic surfactants, and disinfectants and successfully applied to removal of scales on the cleaning beds and distribution reservoir at city D waterworks.

• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.467-472
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• 2003

In this study, an algal fence was developed and applied to reduce the input of algal scum into the water intake facility. The effectiveness of vertical algal fences(overlapped three types of meshes, (312 ${\mu}m$ ${\times}$ 375 ${\mu}m$, 390 ${\mu}m$ ${\times}$ 450 ${\mu}m$, and 0,7 cm ${\times}$ 1cm; vertical depth, 1.5 m; length of fence, about 120 m)) was experimentally tested at a water intake facility (Mulgum, lower Nakdong River). The application of the fence resulted in the statistically significant difference of algal biomass between inside and outside of the fence. According to ANOVA test, chi. a concentration in Day-1showed large difference at each depth of 0, 1, 2 m (0.001> p at each depth, n = 16 respectively). Especially large difference was observed at 0 and 1 m depth. However, the fence was only effective for a short period and its efficiency declined by Day-5after the installation. When better maintenance options for the fence are prepared, e.g. mechanical installation and periodic backwashing of the fence, the performance of algal fence may be sustained. In addition, reliable models for bloom prediction are required to provide an advanced indication of the optimal timing for the installation so that effective operation would be achieved.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.432-438
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• 2011

We need to make the standard of the best baffle shape and L/W ratio of clearwell due to insufficient disinfection in short L/W ratio and uneconomic design in long L/W ratio. The objectives of this research were to evaluate the best shape of baffle and economic L/W ratio in the all sorts of shape and size by using computational fluid dynamics. In the results of this research, the baffle with smaller number of turning flow is more beneficial for hydraulic efficiency. So, even if the same shape and structure, baffle should be designed as smaller number in turning flow. The best shape of baffle is ZigZag type (model 2) and the worst shape is Distributed types (model 4). The ZigZag type can reduce number of baffle about 67% than that of the Distributed types. In the ZigZag type, economic L/W ratio is 30~50. If L/W ratio exceed over 50, it is not economic because construction costs greatly increase and an increasing rate of $T_{10}/T$ is very small.