This study set up the revenue water ratio that could be achieved within the range of the expenses of the water distribution network maintenance project, developed an analysis methodology that could estimate the additional project quantity to achieve the target revenue water ratio of 85% and applied and verified that to S. City. This methodology allowed the distribution of the leakage quantity for each leakage component by the pipeline through the total revenue water account balance analysis and BABE approach and the redistribution into the calculated leakage quantity more accurately through a step test. In addition, the level of reduction in leakage and the quantity of the project were estimated before and after the application of four strategies for the promotion of the revenue water ratio presented by IWA, according to the leakage components by the pipeline. As a result of the application of this analysis method to S. City, it would be possible to achieve up to the revenue water ratio of 81.0%, which was 74.7% in the beginning, if the water distribution network maintenance project was promoted within the range of the project expenses, and to achieve the revenue water ratio of 85.0%, the goal of the project, it would be necessary to replace the pipeline of 22.2% of the entire pipelines in the target area. As a result of the re-estimation of the revenue water ratio achievable, applying the actual water distribution network maintenance quantity in the scope of the business with the results of this analysis, the revenue water ratio was 81.7% while the actually measured revenue water ratio was 82.3%. Thus, the reliability of this analysis method could be secured to some extent.
In this study, we collect water control valves that have had accidents due to existing cracks, etc. are collected, and propose investigation items for strengthening the valve structural safety evaluation through a series of analyzes from valve specifications to physicochemical properties are proposed. The results of this study are as follows. First, there was a large variation in the thickness of the body or flange of the valves to be investigated, which is considered to be very important factor, because it may affect the safety of the valve body against internal pressure and the flange connected with the bolt nut. Second, 60% of the valves under investigation had many voids in the valve body and flange, etc. and the decrease in thickness due to corrosion was relatively large on the inner surface in contact with water rather than the outer surface. It is judged that the investigation of depth included voids is very important factor. Third, all valves to be investigated are made of gray cast iron foam, and therefore it is judged that there is no major problem in chemical composition. It is judged that the chemical composition should be investigated. Fourth, as a physical investigation item, the analysis of metal morphology structure seems to be a very important factor for nodular cast iron from rather than a gray cast iron foam water valve with a flake structure. As it was found to be 46.7~68.8% of the standard recommended by KS, it could have a direct effect on damage such as cracks, and therefore it is judged that the evaluation of tensile strength is very important in evaluating the safety of the valve.
This study set up the estimates of leakage management efficiency evaluation and leakage management goal that could be used in local water distribution networks efficiency business and modernization business. The data were analyzed using data envelopment analysis and multiple regression analysis. To this end, with leakage management input indices concerning leakage reduction activities (e.g., aged pipe replacement, water meter replacement, leakage restoration, and leakage detection) and leakage management calculation indices (e.g., the increase of revenue water ratio and the reduction of leakage ratio), the data on 22 K-water consignment local water supply systems were analyzed for the years from 2004 through 2018. Using the results of efficiency analysis by data envelopment analysis, the other DMUs (Decision Making Unit) benchmarked the DMU with the highest efficiency to maximize the leakage management efficiency for all DMUs. Through this, leakage management goal estimates were drawn with the input indices of four leakage reduction activities and calculation indices of the increase of revenue water ratio and the reduction of leakage ratio by multiple regression analysis for each group based on the revenue water ratio and leakage ratio. The correlation coefficients of the leakage management goal estimate for the criteria for the revenue water ratio amounted to 0.553 and 0.771. The correlation coefficients of the leakage management goal estimate for the criteria for leakage ratio were 0.397 and 0.865. Accordingly, we estimated the quantity and priority of four leakage reduction activities for the target leakage ratio and revenue water ratio.
The purpose of this study was to evaluate the corrosion damage of large diameter metallic pipes buried in reclaimed land due to the corrosion effect by soil, and to propose a method of installing metal pipes in the reclaimed land. The results are as follow. First, the soil of the reclaimed land was gray clay, the soil specific resistance indicating soil corrosiveness was at least 120 Ω-cm, the pH was weakly acidic(5.04 to 5.60), the redox potential was at least 62 mV, the moisture content was at most 48.8%, and chlorine ions and sulfate ions were up to 4,706.1 mg/kg and 420 mg/kg. Therefore, the overall soil corrosivity score was up to 19, and the external corrosion effect seems to be very large. Second, the condition of straight part of pipes was in good condition, but most of KP joints were affected by corrosion at a severe level. The reason for this seems to be that KP joints accelerated corrosion due to stress and crevice corrosion in addition to galvanic corrosion in the same environment. Third, as a result of evaluating correlations of each item that affects the corrosion on the external part, the lower the soil resistivity and redox potential, the greater the effect on the KP joints corrosion, and the moisture content, chloride ion, and sulfate ion, the higher the value, the greater the effect on the corrosion of KP joints. In addition, among soil corrosion items, the coefficient of determination of soil resistivity with corrosion of KP joints was the highest with 0.6439~0.7672. Fourth, when installing metal pipes or other accessories because the soil of the reclaimed land is highly corrosive, it is necessary to apply a corrosion preventive method to extend the life of pipes and prevent leakage accidents caused by corrosion damage to the joint.
In this study, a model to optimize residual chlorine concentrations in a water supply system was developed using a multi-objective genetic algorithm. Moreover, to quantify the effects of optimized residual chlorine concentration management and to consider customer service requirements, this study developed indices to quantify the spatial and temporal distributions of residual chlorine concentration. Based on the results, the most economical operational method to manage booster chlorination was derived, which would supply water that satisfies the service level required by consumers, as well as the cost-effectiveness and operation requirements relevant to the service providers. A simulation model was then created based on an actual water supply system (i.e., the Multi-regional Water Supply W in Korea). Simulated optimizations were successful, evidencing that it is possible to meet the residual chlorine concentration demanded by consumers at a low cost.
In this study, air scouring cleaning was selected and applied among 5 small blocks (S1~S5) in domestic S cities to analyze the cleaning effect of particles causing discoloration. In order to identify the cleaning effect, 10 locations were selected as water quality investigation point, such as the stagnant or water mains ends. Removal of solids, variation of particle components, weight and concentration were analyzed. And the level of the cleanness of the surface inside water mains using endoscope was investigated. As a result of analysis, the solids discharged after cleaning were mainly sand and gravel, pieces related to pipe materials, and corrosion products. As a result of analyzing the concentrated particles of the filter before and after cleaning, it was found that the change in discoloration on the filter was large. In addition, as a result of comparing the weight and the concentration of the particles, it was found that the particles causing discoloration were significantly removed after cleaning. From the results of the endoscopy, it was confirmed that most of the precipitated and accumulated dark yellow discoloration matters inside water mains were removed through cleaning. Therefore, it seems that the particles causing discoloration in water decreased after cleaning. Therefore, it is expected that, if properly cleaning was applied, matters that cause discoloration can be removed from the water mains, and customer's complaints can also be reduced through water quality improvement.
This study would present a risk analysis method to evaluate stable tap water supply in a multi-regional water supply system and propose a measure for the evaluation of the effect of the conjunctive operation of the multi-regional water supply system using this. Judging from the vulnerability for the crisis response of the entire N. multi-regional water supply system, as compared to the result of Scenario 1 in which no conjunctive pipes were operated, it was found that in Scenario 2, in which conjunctive pipes were partially operated, the vulnerability of crisis response decreased by about 30.6%, and as compared to Scenario 3, the vulnerability of crisis response decreased by 86.2%. In setting a plan for stable tap water supply in N multi-regional water supply system, using the estimated value and the method for the evaluation of the vulnerability of crisis response by pipe, by interval and by line, it is judged that this can be utilized as a basis for the judgment of the evaluation of the operation or the additional installation of conjunctive pipes.
This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.
본 연구는 세계미술시장에서 저평가 되어 있는 한국의 미술품들의 정당 한 가격형성에 도움이 되는 한국형 가격지수개발의 필요성에 대해 연구하 였다. 현대사회 시장의 영역에서 자주 언급되는 미술작품의 가격 산정은 일반적인 공산품과 달리 세계 미술계의 풀리지 않는 숙제이다. 작품의 가 격형성에 있어 가격을 정하는 ‘기준’들이 명확하지 않다는 점이 가장 큰 문제이다. 한국미술계에서 통용되는 미술품 가격은 통상 작가나 갤러리 혹은 관객이 결정하기도 한다. 여러 노력에도 불구하고 여전히 호당가격 제로 대부분의 작품가격이 형성되고 있으며, 믿을 수 있는 가격을 위해 참 고하는 자료들은 작가의 이름과 약력, 평론가의 논평 등이다. 현재 미술시 장의 가격형성방식은 갤러리 및 작가에 의한 산정방법과 경매낙찰가를 기 준으로 산정되는 방법이 있다. 이 연구는 이 가운데 산정기준이 좀 더 명 확한 경매낙찰가에 근거하여 시장경제 안에서 가격이 형성될 수 있는 방 법을 고찰하고자 하였다. 서양 미술시장에도 국내시장과 마찬가지로 호당가격제가 존재하지만 이를 보완할 수 있는 자산지수로 검증된 미술품 가격지수에 의해 시장 내 작품가격을 정당화 시키고 있다. 한국 미술시장의 역사는 비교적 짧기 때 문에 반복매매에 따른 기록이 부족하고 여러 기관에서 한국형 미술지수의 개발에도 불구하고 현재까지 시장의 신뢰를 얻지 못했다. 미술지수에는 미술품의 특수성을 감안해 예술적 가치라는 정성적인 분석이 포함되어야 하지만 현재까지 개발된 한국의 미술지수들은 이를 포함하지 않은 아직 초보적인 단계이다. 믿을 수 있는 가격지수의 부재로 내국인뿐만 아니라 외국인들도 한국의 미술품을 거래할 때 많은 혼란이 있다. 이러한 차원에 서 미술품의 특성과 현대미술시장의 현황에 대해 고찰한 다음, 문헌조사 를 통해 국내에서 개발되었던 미술지수 (KAPPA, KAMP)와 세계미술 시 장의 대표적인 메이모제스와 아트프라이스닷컴의 가격지수 사례들을 분 석하였다. 이를 통해 한국형 미술지수의 필요성에 대해 강조하였다.
The estimation method of economical leakage management target utilized upon planning business for improvement of revenue water ratio in South Korea is presented and applicability of methods developed in this study is assessed through application on site. With a consideration of revenue water ratio in application target area, estimation method of long-term economical leakage management target is applied. Three leakage reduction methods such as replacement of residual aged pipe, leakage investigation and restoration and water pressure management are applied with a consideration of characteristics of site. Due to difficulty of obtaining data, analysis of cost/benefit by leakage reduction methods is performed by applying method of leakages estimation equation among statistical methods. As a result of application, revenue water ratio corresponding to long-term economical leakage management target is 91.6 %.
This study attempts to draw factors for an analysis of the operation effect of a rechlorination facility and autodrain equipment for residual chlorine equalization by installing and operating a rechlorination facility and autodrain equipment in P City and analyzing the practical evaluation method and operation effect. For this purpose, this study selected three indicators for an analysis of the effectiveness of residual chlorine equalization and conducted a comparative analysis before and after the implementation of the residual chlorine equalization. As a result of estimation, ① the reduction of the residual chlorine concentration range from a water treatment plant to the pipe end was 16.0%; ② the total reduction of chlorination input was 18.0%; and ③ the reduction of the generation of disinfection by-products was 19.5%. In addition, this achieved enough residual chlorine equalization in the supply process and shows that it could successfully achieve the economic feasibility of investment in equipment and the reduction of the generation of disinfection by-products. Like this, it is judged that the three indicators suggested in this study will be used sufficiently as indicators of an analysis of the effectiveness of residual chlorine equalization according to the operations of the rechlorination facility and autodrain equipment.
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%).
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.
This research carried out an analysis on input cost and leakage reduction effect by leakage reduction method, focusing on the project for establishing an optimal water pipe network management system in the Taebaek region, which has been executed annually since 2009. Based on the result, optimal cost-benefit analysis models for water distribution network rehabilitation project were developed using DEA(data envelopment analysis) and multiple regression analysis, which have been widely utilized for efficiency analysis in public and other projects. DEA and multiple regression analysis were carried out by applying 4 analytical methods involving different ratios and costs. The result showed that the models involving the analytical methods 2 and 4 were of low significance (which therefore were excluded), and only the models involving the analytical methods 1 and 3 were suitable. From the result it was judged that the leakage management method to be executed with the highest priority for the improvement of revenue water ratio was installation of pressure reduction valve, followed by replacement of water distribution pipe, replacement of water supply pipe, and then leakage detection and repair; and that the execution of leakage management methods in this order would be most economical. In addition, replacement of water meter was also shown to be necessary in case there were a large number of defective water meters.
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.
항산화 및 항균활성을 가진 천연물을 활용해 합성보존료를 대체하고자 하는 연구가 활발한 가운데 국내 자생 식물 중 135종을 대상으로 DPPH radical 소거활성을 측정하였다. 이중 항산화 활성이 10%대로 낮게 나타난 식물 8종에 대해 항균효과를 조사하였다. 식물 추출물의 DPPH radical 소거활성은 0.41~94.84%로 다양하였으며, 가장 효과가 좋은 식물은 꽃향유와 우엉으로 각각 94.84, 80.55%를 나타내었다. 우엉은 잎의 경우 26.87, 뿌리 19.29%의 활성을 나타내 동일 식물이라도 추출부위에 따라 활성의 차이가 있을 것으로 보인다. 선이질풀과 비쭈기나무는 각각 그람양성균인 B. subtilis, 그람음성균인 E. coli 및 Candida속인 C. albicans에 대해 2.2~10.8 mm 수준의 항균활성을 나타내었다. 각 식물에 대한 다양한 추출법을 적용하여 기능성을 확인하고 이들 항산화성 물질에 대한 추가 연구가 진행되어야 할 것으로 사료된다.