Pipe Deterioration Prediction (PDP) and Pipe Failure Risk Prediction (PFRP) models were developed in an attempt to predict the deterioration and failure risk in water mains using fuzzy technique and the markov process. These two models were used to determine the priority in repair and replacement, by predicting the deterioration degree, deterioration rate, failure possibility and remaining life in a study sample comprising 32 water mains. From an analysis approach based on conservative risk with a medium policy risk, the remaining life for 30 of the 32 water mains was less than 5 years for 2 mains (7%), 5-10 years for 8 (27%), 10-15 years for 7 (23%), 15-20 years for 5 (17%), 20-25 years for 5 (17%), and 25 years or more for 2 (7%).

구조물에 충격하중이 작용하면, 그 구조물은 통상적으로 대변형을 동반하는 소성변형과 최종적으로 그에 따른 파단을 경험하게 된다. 본 연구에서는 사고적 극한 상태에 대한 합리적인 설계를 위해 열성형된 판과 냉간성형된 판의 재료상수를 고속인장시험에 대한 수치시현을 통해 정의하였다. 변형율이 중간 속도 이하인 경우에는 변형율 속도의 영향을 무시할 수 있다는 가정과 함께 Cower-Symond 모델과 John-Cook 모델에 포함되는 재료상수들의 유용성을 참고문헌들의 결과와 비교하여 입증하였다. 본 논문은 향후 연구 내용에 대한 언급을 포함하면서 마무리하였다.

In the water supply pipeline system, pipes made by cast iron, PE, PVC are generally used. However, the structural performance of these materials can be declined when used for long periodsof time because of corrosion, creep, deterioration of the material, etc. while glass fiber reinforced polymer plastics (GFRP) have many advantages such as light-weight, corrosion resistance, smooth surface, etc. For these reasons, GFRP pipes are good for construction when it is buried underground and are increasing trend in applying the water supply pipeline system. Therefore, more optimized structural design methodology should be developed. In this paper, we confirm pipe stiffness (PS) of GFRP pipe in which the pipe stiffness indicates the load-bearing performance. We compared data of parallel-plate loading test and theoretically predicted PS by the classical elasticity theory and the finite element method (FEM).

In the water supply pipeline system polyethylene (PE), polyvinyl chloride (PVC), and ductile cast iron pipe are mostly used. However, they have some problems such as reduced durability due to material degradation, defects in connections, the pipelines breakage, and lack of continuous maintenance. Recently, research on durable and outstanding corrosion resistance glass fiber reinforced polymer plastic (GFRP) pipe is being actively conducted. GFRP is classified into the flexible pipe and when soil pressure and live load act on buried GFRP pipe, the load acting on the pipe is transferred to the surrounding soil. So, pipe will support the load with the surrounding soil. In this paper, to apply GFRP pipe for the water supply pipeline system, the structural reliability of GFRP water supply pipe buried underground should be investigated by examining the mechanical properties of GFRP pipe as well as the soundness of the pipe under buried state. The field test of buried pipe is conducted and the results are analyzed and discussed.

In this study, Hazen-Williams C value of pipes in wide waterworks system was estimated and statistically analyzed. Hazen-Williams C value of water pipe was predicted after 20 years of service period. From the results, it was found that C value of water pipe for treated water maintained higher value of 110 after 20 years of installation. Furthermore, it was found that velocity coefficients of steel pipe for less than and more than 20 years of installation were 117.7 and 109.3, respectively. C value of ductile iron pipe for less than and more than 20 years of installation were 118.1 and 114.2, respectively. In this study, it was also found that small value of C is used in the design of water pipe system. Therefore, excessively bigger size of pipe can be determined in the design of water pipe system. From the results of present study, optimum value of C can be used to avoid the oversized design of water pipe system.

In this study, determination methods of monitoring location in water distribution system were suggested and applied to real test bed. Small block of Gwangtan water distribution system is consisted of 582 pipes, 564 junctions, 1 reservoir, and 1 pump station. Small block of Ho Chi Minh water distribution system is consisted of 162 pipes, 148 junctions, and 1 reservoir. Two small block water distribution systems were analyzed by pressure contribution analysis method to determine the optimum monitoring locations. The pressure change was estimated at each junctions by the additional demand at a junction. From the results, the optimum monitoring location can be determined by rank of pressure contribution index at each junctions due to demand change at a junction.

It analyzes the new structure and mechanism of organ type accel pedal to have a double curve to obtain a low effort force has been devised an electronic accel pedal consisting of two springs. To confirm the characteristics of effort force on variation of spring constants for two springs, dynamic analyzes were performed by using the ADAMS software program. According to the result of the simulation analysis, new mechanism of organ type accel pedal has an inflection point of the curve of pedal effort force on variation of spring constants, k, in various range of pedal angle.

금속 유기 골격체(Metal Organic Framework, 이하 MOF) 종류의 하나인 제올라이트형 이미 다졸레이트 골격체(Zeolitic Imidazolate Framework, 이하 ZIF) 중 ZIF-8은 Zn 금속이온과 imidazole 유기 리간드의 결합으로 이루어져 있다. 본 연구에서는 여러 종류의 용매에서 합성된 ZIF-8의 1차 결정과 2차 입자의 형성이 용매가 가진 특성에 영향을 받는 것을 확인하였다. HBD(hydrogen bond donation) 값이 큰 용매에서 합성된 ZIF-8의 1차 결정은 HBD 값이 작은 용매에서의 것보다 크기가 컸고, 용매의 유전상수의 값이 작을수록 2차 입자의 크기가 큰 ZIF-8이 합성되었다.

Deposits discharged through the cleaning mainly were cement mortar, bitumen paintings and rust pieces, and fragments of perforation, stones and gravels. Deposits were more removed through swabbing pig cleaning rather than air scouring cleaning on the whole. However, air scouring cleaning were not influenced by the constraint conditions such as a change in the diameter or the presence of the valve in water mains compare to swabbing pig cleaning. So, it was thought that air scouring cleaning might be more favorable to water distribution network cleaning in the future. After the cleaning, water quality including residual chlorine and turbidity also was improved because of the removal of a significant amount of the deposits. Therefore, if the cleaning is continuously and regularly implemented in water mains, it is expected that it will help to recover the reliability and to preserve the health of water quality.

In general, it is required mechanical properties and strength tests to use the material in engineering applications. The material fringe values of photoelastic materials vary with the supplier, the batch of resin, temperature and age, it is necessary to calibrate each of sheet of photoelastic material at the time of the test. In this paper, we perform tensile tests and calibrations tests for photoelastic stress fringe constant in order to obtain the mechanical properties of materials and photoelastic material fringe constants of PMMA and PSM-1. From this tests, the tensile strength of PMMA and PSM-1 were 100.5 MPa and 71.5 MPa, respectively. Also, the measured material stress fringe constants of PMMA and PSM-1 were 13.33 N/mm and 6.91 N/mm, respectively.

In a photoelastic experiment, it is necessary to know the material stress fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. This type of compensator was proposed by the previous researchers. The recent image processing development of the stress pattern provide a means for making convenient compensator. The material stress fringe constant is determined using the distributions of isochromatic fringes in the wedge shaped plate under tensile load. The stress fringe constant measured with this method is applied to obtain the stress distribution along the central line on the tapered shank of the wedge-shaped plate. Photoelastic results using the measured material fringe constant are compared with FEM analysis. Two results are comparable, so it can be seen for the measured material fringe constant to be valid.

Aging water pipe networks hinder efficient management of important water service indices such as revenue water and leakage ratio due to pipe breakage and malfunctioning of pipe appurtenance. In order to control leakage in water pipe networks, various methods such as the minimum night flow analysis and sound waves method have been used. However, the accuracy and efficiency of detecting water leak by these methods need to be improved due to the increase of water consumption at night. In this study the Principal Component Analysis (PCA) technique was applied to the night water flow data of 426 days collected from a water distribution system in the interval of one hour. Based on the PCA technique, computational algorithms were developed to narrow the time windows for efficient execution of leak detection job. The algorithms were programmed on computer using the MATLAB. The presented techniques are expected to contribute to the efficient management of water pipe networks by providing more effective time windows for the detection of the anomaly of pipe network such as leak or abnormal demand.

Many polymers exhibits sufficient birefringence to be used as photoelastic specimen material. Common polymers as polymethylmethacrylate (PMMA) are often used as photoelastic specimen. In a photoelastic experiment, it is necessary to know the material fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. The material stress fringe constant is determined using the simple tension specimen. The stress fringe constant measured with this method is applied to obtain the stress distribution in a tensile plate with a circular hole. Photoelastic results using the measured material fringe constant are compared with FEM analysis. Two results are comparable, so it can be seen for the measured material fringe constant to be valid.

District Metered Area (DMA) construction is one of the most cost effective alternatives for management of water loss (i.e., water leakage) and energy consumption (i.e., water pressure) in water distribution systems. Therefore, it’s being implemented to numerous new and existing water distribution systems worldwide. However, due to the complexity of water distribution systems, especially large-scale and highly looped systems, it is still very difficult to define the optimal boundary of DMAs considering all the aspects of water distribution system management requirements. In this study, a DMA design methodology (or a DMA design model) was developed with Geographic Information Systems (GIS) and hydraulic distribution system model to determine the optimal DMA boundary.

When designing Water Distribution System (WDS), determination of life cycle for WDS needs to be preceded. And designer should conduct comprehensive design including maintenance and management strategies based on the determined life cycle. However, there are only a few studies carried out until now, and criteria to determine life cycle of WDS are insufficient. Therefore, methodology to determine life cycle of WDS is introduced in this study by using Life Cycle Energy Analysis (LCEA). LCEA adapts energy as an environmental impact criterion and calculates all required energy through the whole life cycle. The model is build up based on the LCEA methodology and model itself can simulate the aging and breakage of pipes through the target life cycle. In addition the hydraulic analysis program EPANET2.0 is linked to developed model to analyze hydraulic factors. Developed model is applied to two WDSs which are A WDS and B WDS. Model runs for 1yr to maximum 100yr target life cycle for both WDSs to check the energy tendency as well as to determine optimal life cycle. Results show that 40yr and 54yr as optimal life cycle for each WDS, and tendency shows the effective energy is keep changing according to the target life cycle. Introduced methodology is expected to use as an alternative option for determining life cycle of WDS.

In this paper, a System Dynamics(SD) computer simulation model has been developed to assess the effects of developing and providing an alternate water source. A water service index was also developed to estimate the level of overall customer satisfaction on water supply service. Data from the Busan water supply service and the Korea Development Institute regarding the Nak Dong river bank storage development were utilized during the modeling processes. Some important indicators of the system under study were analyzed by the simulations of development of the alternate water source for Busan. The developed SD model and the water service index can be further utilized as a tool that can assess the extent and timing of an additional service improvement project.

This study was carried out to analyze water suspension in the water supply system through fault tree analysis. And quantitative factors was evaluated to minimize water suspension. Consequently the aim of this study is to build optimal planning by analyzing scenarios for water suspension.Accordingly the fault tree model makes it possible to estimate risks for water suspension, current risks is 92.23 m3/day. The result of scenario analysis by pipe replacement, risks for water suspension was reduced 7.02 m3/day when replacing WD4 pipe. As a result of scenario analysis by water district connections, the amount of risk reduction is maximized when it is connecting to network pipe of D Zone. Therefore, connecting to network pipe for D Zone would be optimal to reduce risk for water suspension.

With the advent of lean-six sigma era, an extensive use of analytic tools such as control charts is required in the field of manufacturing. In relation to statistical quality control (SQC) or process control (SPC), the Korean standards have undergone a meaningful change. In this study, the theoretic backgrounds for evaluating the control limits in connection with the variable control charts are examined in view of better understanding the related constants and coefficients. This paper is intended to help the quality control practitioners understand the mathematical backgrounds by comparing related quality control constants and also to encourage them to make use of and to take the advantage of the variable control charts which are very useful for implementing the concept of lean-six sigma in many industrial sites.

Tuberculation and slime accumulated in water mains play an important role in modifying water quality of drinking water. Therefore, in this study, it was investigated that what materials were accumulated, and what components were included in the tuberculation and slime of water mains. The Various tuberculation and slime sample were collected from the 12 water mains to analyze their physical and chemical properties and crystal structure. As a analysis method, VSS(Volatile suspended solid), SEM(scanning electron microscope), EDS(Energy Dispersive X-ray spectroscope), ICP(Inductively Coupled Plasma Mass Spectrometer) and XRD(X-Ray Diffractomete) were used. The results of analysis on the samples, the representative materials were verified such as iron corrosion products, the fine sand particles generated during backwash, fine particles of activated carbon, aluminum used in coagulation process, and manganese included in raw water.

목 적: 성인과 아동에서 굴절이상 정도와 안광학 상수 간에 상관성이 감소하는 시점을 알아보고자 하였 다. 방 법: 청주에 거주하는 194명(성인 116명, 아동 78명)을 대상으로 자동굴절력계와 안구계측기로 굴절검 사와 안광학 상수를 측정하였다. 각막곡률반경과 전안방 깊이는 전안부 안광학 상수로, 안축장은 후안부 안 광학 상수로 이용하였다. 전안부와 후안부의 통합된 안광학 상수인 안축장 대 각막곡률반경의 비(AL/CR ratio)와 굴절이상 정도의 관련성을 제시하였다. 각 안광학 상수와 굴절이상 정도와의 관련성을 확인한 후 안축장에 따라 안광학 상수 간의 상관성이 없어지는 값을 찾고, 이를 등가구면굴절력으로 제시하였다. 결 과: 성인과 아동에서 굴절이상 정도와 안광학 상수들 간의 상관관계는 안축장과 각막곡률반경을 각각 적용하였을 때 보다 안축장 대 각막곡률반경비(AL/CR ratio)로 나타날 때 설명력이 높았다(아동 그룹 r2=0.681, p=0.000, 성인 그룹 r2=0.723, p=0.000). 성인과 아동에서 전안부와 후안부의 안광학 상수 사이 에 상관성이 없어지는 안축장의 길이를 찾았다. 아동에서 각막곡률반경과 안축장의 상관성은 안축장 24 mm 를 기준으로(r=-0.174, p=0.238), 전안방 깊이와 안축장은 25 mm를 기준으로(r=-0.153, p=0.585) 안축장 이 길어질 때 상관성이 없어지는 것으로 나타났다. 성인에서 각막곡률반경과 안축장의 상관성은 24.5 mm를 기준으로, 전안방 깊이와 안축장은 26.0 mm를 기준으로 안축장이 길어질 때 상관성이 없어지는 것으로 나 타났다(r=0.178, p=0.083, r=0.054, p=0.796). 기준점이 되는 각 안축장 값을 등가구면굴절력으로 나타냈 을 때 아동에서 24 mm는 약 -1.30D, 25 mm가 약 -3.20D로 나타났고(r2=0.609) 성인에서 안축장 24.5 mm가 약 -2.10D, 26 mm가 약 –4.30D로 나타났다(r2=0.450). 결 론 안광학 상수 간의 상관성은 정시를 벗어나 어느 정도 비정시가 된다 하더라도 지속적인 상관관계 를 나타낸다. 따라서 정시화는 특정 나이나 시력에 대한 기존의 기준과 더불어 지속적 연구를 통해 안광학 상수 간의 상관성 유무에 대한 고려도 함께 이루어져야 할 것이다.