• Management & Information Systems Review
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• v.36 no.3
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• pp.89-111
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• 2017

The era of today's day is that the era of the black gold age is now approaching the era of the blue gold age. As the importance of water increases, support and policies for the water industry are presented. The water industry is a public service industry but it faces the problem for unbalanced supply between users. One of solutions for solving the problem at hand is the privatization of the public service and it is the most sensitive and focused subject to the issue. Korea is also coming up for the privatization of the water industry. So, one of the privatization operations based on the privatization of the current waterworks law is management contract by the specialized organization and it is in progress to enhance the efficiency of public services. Therefore, this study aims at finding out the local water supply services' efficiency by K-Water using DEA(Data Envelopment Analysis), and productivity analysis by malmquist index on 18 organizations of the implementation of local water supply management contract using the date from 2012 to 2014. According to the result of the DEA, 10 of the 18 organizations were the most efficient during 3 years and malmquist index for analysing the productivity was decreasing. That is because of the leakage ratio and utilization ratio of the raw water and both of them are significant to productivity. As a result, this study differs from the previous studies by analysing efficiency and productivity using DEA and malmquist index to the solution for the problem faced by current water industry.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.4
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• pp.573-585
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• 2019

The objective of this study is to propose the drainage system that has been improved the workability, waterproofing and drainage performance to treat the leakage from the cement concrete structures in underground. It is improved that the pipe for conveying ground leak in the existing drainage system had the problem in workability and waterproof. The drainage systems with the improved pipe for conveying ground leak were constructed in conventional concrete lining tunnels to evaluate the workability, waterproofing and drainage. The waterproof and the drainage performance of the drainage system was evaluated by injecting 1,000 ml of red water in the back of the drainage system at 3 weeks, 6 weeks, 9 weeks, 11 weeks, 14 weeks, 17 weeks and 23 weeks. During 6 months of field performance test, the average daily temperature of the tunnel site was measured from $-12.4^{\circ}C$ to $19.7^{\circ}C$. The daily minimum temperature was $-17.2^{\circ}C$ and the daily maximum temperature was $26.7^{\circ}C$. There was no problem in waterproof and drainage performance on the pipe for conveying ground leak and the drainage system during 6 months for field performance test. It is concluded that the improved drainage system can be applied to various cement concrete underground structures where leakage occurs, and has little seasonal effect.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.2
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• pp.31-41
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• 1998

As the leakage of crude oil from tankers breaks out frequently, it caused a serious problem for ocean pollution and calls for developing treatments to handle the leaked crude oil and mitigate the pollution. Thus it is required to develop new purification technolgies and appropriate treatment systems which have sufficient treatment capability in order to cope with the anticipated ocean pollution. In this experiment, A and B type heavy oils were used to make the emulsion of both water containing heavy oil and sea-water containing heavy oil. The following are the main results from this study ; 1. When A and B type heavy oils were added to the original sea-water and treatedin the homogrenizer respectively, the particle of oil beacame smaller in both cases. Under the same condition, while the initial oil density of sea-water containing B-heavy oil is higher than of emulsion with A-heavy oil, the particle of A-heavy oil is finer than that of B-heavy oil. 2. When A and B type heavy oils were added to distilled water and treated in the homogenizer respectively, the particle was more dispersed and finer than that in the case of sea-water in both cases. In this result, the water containing oil formed more stable emulsion than the sea-water containing oil. 3. In this experiment, all emulsions showed oil in water types. 4. Since the oil particle is larger in the sea-water than in the distillated water, interms of elimination of oil, it is thought to be more important to give Membrane treatment after implementing sandfilter, activity carbon, coagulation-sedimentation and floating separation as pre-treatment.

• Journal of the Korea Institute of Building Construction
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• v.23 no.4
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• pp.337-348
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• 2023

The central objective of this study is to curtail the leakage of mortar or cement paste, often resultant of ill-constructed formwork, by implementing thixotropy in the formulation of high-fluidity, standard-strength concrete. When such concrete is utilized in smaller scale construction projects, instances of formwork gaps due to suboptimal construction precision may lead to significant leakage of mortar and paste, a problem not typically encountered with traditional slump-flow concrete. In this investigation, Polyvinyl Alcohol(PVA) and borax are incorporated into the concrete mixture to induce thixotropy. The experimental design includes varying methodologies for integrating PVA and borax, while assessing alterations in diverse concrete performances, including thixotropy and leakage reduction potential that simulates formwork gap conditions. Under the experimental conditions defined within this study, it was found that replacing, rather than merely adding PVA and borax, aids in averting water addition via suspensions. This approach yielded promising results in terms of concrete properties and proved efficacious in stemming leakage in concrete possessing sufficient thixotropy. Notably, when a 6% PVA suspension was substituted, a significant reduction in leakage was observed. Consequently, it is projected that construction quality can be ensured, even with lower precision formwork, by applying thixotropy to concrete through the use of PVA and borax.

• Geomechanics and Engineering
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• v.15 no.4
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• pp.997-1004
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• 2018

The brine leakage is a tough problem in artificial freezing engineering. This paper takes the common soft clay in Wujiang District as the study object, and calcium chloride solutions with six salinity levels were considered. The 'classic' cooling curve method was employed to measure the freezing point of specimens after freeze-thaw. Results indicate that four characteristic stages can be observed including supercooling, abrupt transition, equilibrium and continual freezing, strongly dependent on the variation of unfrozen water content. Two characteristic points were found from the cooling curves, i.e., freezing point and initial crystallization temperature. A critical value for the former exists at which the increment lowers. The higher the saline content approximately linearly, lower the freezing point. In the initial five cycles, the freezing point increases and then stabilizes. Besides, the degree of supercooling was calculated and its correlations with water, salt and freeze-thaw cycles were noted. Finally, an empirical equation was proposed for the relationship of freezing point and three main factors, i.e., water content, saline content and freeze-thaw cycles. Comparison of calculated and measured data proves that it is reliable and may provide guidance for the design and numerical analysis in frozen soil engineering.

• Fashion & Textile Research Journal
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• v.17 no.6
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• pp.1013-1019
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• 2015

As the interest in leisure and health increases, the domestic outdoor wear industry becomes bigger. The waterproofness of fabrics does not ensure the waterproofness of garments because of the stitch holes during the sewing process even with the seam sealing tapes. Thus the water leakage often becomes a problem during the end use. Still companies use fabrics waterproofness data for garments marketing because they are simple to run the test, less expensive than the whole garment testing, and easy to achieve the quality control. In this study the rain tower system for evaluating the waterproofness of garments has been developed and the waterproofness of the selected waterproof and breathable garments in the market were tested. The rain tower was consisted of rain tower room, rainfall forming system and measurement system. Two different levels of rainfall can be simulated with this system(100l/m²/hr and 450l/m²/hr). Jackets in the market have been tested at two different rainfall conditions. The temperature and humidity data inside jackets didn't provide much information on the waterproofness at severe rainfall condition(450l/m²/hr, 1 hour). However, water leakage was detected on the cotton undershirt inside jacket. 5 out of 8 jackets passed the normal rainfall condition(100l/m²/hr, 30 minutes). The newly developed rain tower system was able to evaluate the waterproofness of the jacket seams. It is recommended the further study on the detailed test conditions for the end use of the waterproof and breathable garments.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.833-836
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• 2008

In this study, we would like to study on the apply properties to salt water environment of pre-hydrated bentonite for complement problem that water leakage to permit salt water that existing bentonite does not initial swelling. Accordingly, execute viscosity properties, swelling properties, permeability and confirmed apply properties to salt water environment. Did not permit initial permeable in test result salt water environment, and permeable did not happen until 72 hours by maximum $3kgf/cm^2$ water pressure. Fresh water environment enough progress of gelation confirm that viscosity and swelling properties confirmation result and as delamination phenomenon of platy formation looked in salt water environment but this as bentonite hydrates crystallization layer swelling that is done consider. Synthetic study results, if compaction condition such as press layer is formed to bentonite upper, applied to the salt water environment of the underground structures of expectations.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.57-62
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• 2012

The purpose of this paper is to find dangerous factors of a water purifier when water leaks due to inappropriate use and analyze the patterns of damaged parts in order to provide data for the examination of the cause of the problem. If the water purifier is inspected and managed by a non-specialist, when the FLC(Float Level Controller) at the top is inclined, water leakage may occur to the water purifier. The leaked water flows onto the cables and hoses and enters the thermostat terminal, heater, PCB, power supply connection connector, etc., becoming a dangerous factor that may cause a system failure, fire, etc. Due to the water that entered the input terminal, low noise and white smoke were generated at first. However, the flame gradually propagated due to the continuous inflow of moisture. It was found that when moisture reached the PCB, a carbonized conductive path was formed at the varistor terminal, input terminal, semiconductor device terminal, etc., and the flame became larger, which might result in a fire. From the metal microscope analysis of a damaged condenser terminal, it was found that the amorphous structure unique to copper cable disappeared, and voids, boundary surface and disorderly fine particles occurred. Also, in the case of the connector into which moisture penetrated, fusion and deformation occurred at the cable connection clips. The result of analysis of the power supply cable connector using a thermal image camera showed that most of the heat was generated from the cable connection clips and the temperature at the connection center was normal.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.799-811
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• 2006

As an alternative measure to replace reactive stance with proactive one, a risk based management scheme has been commonly applied to enhance public satisfaction on water service by providing a higher creditable solution to handle a rehabilitation problem of pipe having high potential risk of leaks. This study intended to examine the feasibility of a simulation model to predict a recurrence probability of pipe leaks. As a branch of the data mining technique, probabilistic neural network (PNN) algorithm was applied to infer the extent of leaking recurrence probability of water network. PNN model could classify the leaking level of each unit segment of the pipe network. Pipe material, diameter, C value, road width, pressure, installation age as input variable and 5 classes by pipe leaking probability as output variable were built in PNN model. The study results indicated that it is important to pay higher attention to the pipe segment with the leak record. By increase the hydraulic pipe pressure to meet the required water demand from each node, simulation results indicated that about 6.9% of total number of pipe would additionally be classified into higher class of recurrence risk than present as the reference year. Consequently, it was convinced that the application of PNN model incorporated with a data base management system of pipe network to manage municipal water distribution network could make a promise to enhance the management efficiency by providing the essential knowledge for decision making rehabilitation of network.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.87-94
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• 2003

Recently, LPLi(Liquied-Phase LPG injection) system is studied for the new stringent emission regulations. But , there are some problems to be solved such as injector tip icing and fuel leakage for LPLi system development. In this paper, the icing problem near injector tip which leads to difficulty of accurate A/F control was studied and reported. Icing of injector tip and port wall was observed at all the cases in this study regardless of injection duration and angle, air humidity change. The spray angle of LPLi was observed approximately two times wider than that of Gasoline injection. This makes the LPLi spray collide with intake port around injector tip. Temperature of the wetted area was decreased and icing of water vapor contained in intake air because of evaporation of the fuel film. The ice of the injector tip and port wall is also affected by the materials related to heat transfer.