• Journal of environmental and Sanitary engineering
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• v.9 no.1
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• pp.17-28
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• 1994

There are many possibilities that may lead to low quality of drinking water Recently, some unknown deposits in tap water raised a lot of public concern regarding the safety of drinking water in Seoul. We analyzed the quality of tap water from several areas of Seoul, including the area where public complaints about tap water were high. The results shows that the quality of tap water in Seoul was good, well below the environmental standards. Only the tap water from the area with high public complaints showed turbidity higher than that of other area. Also, result shows that component of deposit in tap water was Al, Fe, Mn, and Zn. Based on the research result we propose several measures that might help to reduce the amount of deposit in tap water as follows : 1 Using coagulant aid when coagulating or adjusting pH when filtering. 2. Replacing old water pipeline with new corrosive- resistant one. 3. Increasing water treatment efficiency by enhancing water treatment system such as automation of water treatment system adjusting production capacity, and improving operational condition of filler basin. 4. Chlorine disinfection at the distribution reservoir would help maintaining the same pH level and chlorine concentration throughout the water pipeline and reduce corrosion of pipe.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.493-498
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• 2008

Particles or deposit formed by corrosion of the pipe material bring about bad influences on the heating systems with inconvenience, energy loss and so on. In order to obtain the non-corrosive environments, the circulation hot water should properly be treated in several ways to satisfy one or more conditions of the followings: suitable pH-level, low hardness, low oxygen content, low conductivity, low level of chlorides and sulphur compounds and low level of solid particles. This experimental study was carried out to develope the new guidelines on the optimal water quality and directions for water quality management in heating systems. As results, it was recommended that the heating water be maintained pH-level not less than 8, hardness contents as $CaCO_3$ no more than 50 mg/L, turbidity no more than 10 NTU and T-Fe contents 1 mg/L below.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.701-708
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• 2008

As a countermeasure for reduction of corrosion in the delivery and distribution pipes used for tap water, materials for the pipelines in-houses and the effect of water quality on corrosivity of water pipelines were investigated in the distribution system of Han river. As the corrosion index at 6 water purification facilities of Han river, average Langelier Saturation Index (LI) of raw and finished water were -1.0 and -1.4 respectively and average Larson Index (LR) were 9.5 and 9.9, respectively. And also corrosion potential showed corrosivity in finished water (-431~-462 mV) as well as raw water (-426~-447 mV). This results indicate that tap water quality of han river have corrosivity. To understand the corrosivity effect in pipe material used for premise distribution system, water quality of stagnant tap water and tap water were analyzed and the differences between them were calculated. The difference concentration of iron, copper and zinc were $12.9{\mu}g/L$, $31.0{\mu}g/L$ and $45.0{\mu}g/L$ respectively in galvanized steel pipe for use more than 15 years and showed highest concentration. As a result, the control to corrosivity in the water pipelines, corrosivity control treatment in the water purification system can be applied. In advance it is necessary to monitor corrosivity of water quality using corrosive index because corrosivity may differ from the seasonal and regional characteristics and water chemicals dosage. For the future the guideline for corrosion index have to be established.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.839-846
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• 2011

To investigate corrosivity characteristics of raw water in Korea, Langelier index (LI) of 30 multi-regional water treatment plants (WTPs) were evaluated. Annual average values of LI at 30 WTPs were all negative, which means raw water in Korea is very corrosive. LI results for 4 major rivers showed that raw water from Han and Nakdong had relatively high values compared to those of Sumjin and Keum. On the other hand, LI values of raw water from the tributaries of four major rivers were relatively low presumably due to geological characteristics, and in some cases the values were less than -4.0 which means increase of LI is urgently needed to minimize red water problem. Based on the correlation results among LI and water quality parameters, pH, water temperature, calcium concentration were confirmed as major components for LI. Therefore, pH and calcium concentration control is an effective method for the improvement of LI in water treatment processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.170-175
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• 2008

In this study, we developed the CCPP calculating program, which is a kind of index and can determine whether calcium carbonate would precipitate or not in pipe line of water distribution system. Through 9 complicated procedures, CCPP can be calculated. Assuming pH of equilibrium as a first trial, compare the right-hand-side result with left-hand-side result. If the percentage difference between the two results is less than a prescribed tolerance, the initial assumption for the assumed equilibrium pH is adequate. If the difference is too large, make a different assumption and repeat until a result within the prescribed tolerance is achieved. Plugging the intermediate results into the final equation, we could compute the CCPP. Using Fortran and Visual Basic languages, we developed the program. As a result of application of the program, the water quality of intaking water of Han River is highly corrosive by the index of CCPP.

• Journal of the Korean institute of surface engineering
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• v.51 no.2
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• pp.95-103
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• 2018

Recently, many types of constructional steels have been often exposed to under severe corrosive environments due to acid rain with increasing environmental contamination. In order to inhibit their corrosion in severe corrosive environments, a painting method has been widely applied to numerous constructional steels of land as well as marine. Therefore, development of paint having a good quality of corrosion resistance is considered to be very important. In this study, four types of anti-corrosive paints (AP: Phenol epoxy, AC: Ceramic epoxy, AT: Coal tar epoxy, AH: High solid epoxy) were coated to the specimens, and then, were immerged in various salt solutions (0.1, 0.3, 3, 6, 9 and 15% NaCl solutions) for 11 days. And, the corrosion resistance of these samples by effect of osmotic pressure with salt concentration was investigated with electrochemical methods such as measurement of corrosion potential, impedance and corrosion current density. The corrosion current densities of all samples (AC, AT and AH) submerged in 3% NaCl solution exhibited the smallest values compared to other salt solutions. However, in the case of lower values of salt solutions than 3% NaCl solution, the corrosion current density increased again because it makes easier for water, dissolved oxygen and chloride ion etc. to invade toward inner side of coating film due to increasing of the osmotic pressure than 3% NaCl solution, but in the case of higher values of salt solutions than 3% NaCl solution, the coating film is easily deteriorated due to high concentration of chloride ion rather than the osmotic pressure, which resulted in increasing the corrosion current density. In particular, the AC sample indicated the best corrosion resistance in 6% NaCl solution compared to other samples. Consequently, it is considered that the corrosion mechanism of the coated steel plate is completely different from bare steel plate, and the corrosion resistance of coating film by osmotic pressure and chloride ion depend on various types of epoxy of paint in NaCl solution.

• Korean Journal of Veterinary Research
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• v.51 no.1
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• pp.47-53
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• 2011

In Korea, groundwater is main water source in livestock farms. Most dairy and cattle farms have constructed their own wells for human drinking and livestock farming. However, these private residential wells have not been controlled by government and also there was scant study about livestock drinking water quality. Therefore this study was to monitor of the livestock farms' groundwater quality in Korea. Water samples were collected at 123 dairy and cattle farms and were analysed forty six substances with quality standard for drinking water approved by the Minister of Environment. Seventy eight (63.4%) of 123 samples failed to drinking water stand a test. The most frequent contaminants were nitrate-nitrogen and microbial. 22.8% (n=28) of samples showed nitrate-N concentration of higher than 10 mg/L meant that can't be used drinking water for human and the Nitrate-N concentration analysed in the range of 0.2 to 61.2 mg/L. All of 78 failed to drinking samples had microbial problems, especially 5.7% (n=7) of samples indicated water could be contaminated by feces. Other contaminants detected were zinc and evaporation residue. Especially detected zinc concentration (32 mg/L) was about ten times higher than standard of zinc (3 mg/L). Regression analysis indicated that groundwater pH did not influence to nitrate-N concentration but the hardness and chloride could affect to nitrate-N concentration in the groundwater. Most livestock farms were adjacent to crop farmland in Korea. This could cause contamination of groundwater with nitrate-N and pesticide that could accumulate livestock product. Moreover Heavy metal such as zinc and copper could be released from a corrosive plated water pipe in livestock farm. Put together, Korea livestock system is indoor, not pasture-based, hence livestock could be exposed to potential contaminated water consistently. Therefore on the basis of these data, appropriate livestock drinking water quality standards should be prepared to keep livestock healthy and their product safe. Further, livestock drinking water quality should be monitored continuously in suitable livestock drinking water standards.

• Journal of the Society of Disaster Information
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• v.11 no.2
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• pp.253-261
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• 2015

Deterioration of reinforced concrete structures in corrosive environment is tend to be accelerated due to ingress of aggressive ion such as chloride ion. Chloride-induced corrosion is affected by various factors such as cover concrete qualities, width of existing cracks, and cover depth of concrete. However, the allowable crack width of RC structure in design code does not consider the concrete material properties and conditions of construction except the cover depth. In this paper, an equation for allowable crack width is proposed to consider the cover concrete quality, crack width, and cover depth. Crack width, cover depth, and water-cement ratio of concrete are selected as influencing factors on corrosion of reinforcement for rapid chloride tests. From test results, the relationships between the factors and corrosion are derived. Finally, the equation for allowable crack width is derived in terms of concrete compressive strength and cover depth. The presented equation is verified by comparative calculations with design code variables.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.3
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• pp.235-242
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• 2018

Corrosion inhibitors including calcium hydroxide have been used to prevent corrosion in the pipes for tap water supply. The corrosion index (i.e., Langelier Index) differs by area and water quality. The corrosion indices of the areas studied differed by more than 2.0. The 'homogenized' calcium hydroxide was added to the treated water at the K water treatment plant, in order to increase the value of the corrosion index and the concentration of calcium. As the result, the concentration of calcium was increased while the turbidity and pH changed little. The corrosion rate of the tap water with the 'homogenized' calcium hydroxide could be slowed down pretty much. The results suggested that the technology of 'homogenization' of calcium hydroxide can applied to tap water and desalinated water to prevent corrosion in water pipes even in corrosive pipes.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.402-406
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• 1995

The purpose of this paper is to decrease shotcrete rebound losses and to produce economic effectiveness at the same time in construction. The mechanical properties and quick acceleration of various shoterete mixes were analyzed, which were intuenced by several accelerators and their amouts used. And the application and construction in the felds were evaluated. The shotcrete rebounds relied on the condition of construction rather than on the quality of materials, but it is found that the decreasing of the cost and time in shotcreting under the same condition was based on the rebounds which were affected by the accelerating capability of the accelerators. The application of the accelerator was limited by the condition of tunnel construction ; such as ground water, anti-corrosive, or anti-chemistry. It is important to choose a proper accelerator. Therefore, it is necessary that better accelerators which satisfly mechanical characteristics and economy are developed. Optimal working conditions should be announced to the workers and workers' skill be improved in the shotcrete construction feld as well.