• Membrane Journal
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• v.9 no.4
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• pp.193-201
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• 1999

The object of study were the development of membrane process and the optimization of operation condition for membrane system, which was used the pre-treatment system of tap water treatment in steady of conventional process such as coagulation, sedimentation. The higher steady flux is very important factor, by a suitable pre-treatment and optimization of operating condition such as fouling control, crossflow and backwashing method, in membrane system. So, we were observed the effect of flux decline for membrane used by 4 type ultrafiltration(UF) membrane pre-treatment process, and optimized the operation condition of filtration system under various MWCO(Molecular weight cut-off), operation pressure, linear velocity and temperature to maintain higher flux. From these experiment, we were identified that UF process showed a slower flux decline rate and a higher flux recovery than microfiltration(MF) membrane. The water quality of UF permeate was better than that of MF, and was not effected pre-treatment process. In the operation condition, the rate of flux decline was diminished by a higher linear velocity and operation temperature, lower pressure.

• Journal of Sensor Science and Technology
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• v.28 no.5
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• pp.294-298
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• 2019

Pulsed laser-based optical sensor monitoring systems for real time microplastic particle counting are proposed and developed in this study. To develop our real time monitoring system, we used a 450 nm pulsed laser and a photomultiplier with very high quantum efficiency. First, we demonstrated that the microplastic particle counting system could detect standard micro bead samples of 100, 250, and $500{\mu}m$ in river water. We then performed research concerning pulsed laser-based optical spectral sensor systems for real time microplastic monitoring. Additionally, we demonstrated that the real time microplastic remote monitoring system using LoRa communications could detect microplastic in the tap water resource protection area.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.91-101
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• 2014

Three water treatment plants(WTPs) in Jeju island whose source water have different characteristics from those of the mainland of Korea were investigated. Coefficients of bulk water decay($k_b$) of free chlorine at $5^{\circ}C$ for ES, GJ, NW WTPs were $-0.003hr^{-1}$, $-0.002hr^{-1}$ and $-0.001hr^{-1}$ respectively based on bottle tests. To simulate the free chlorine variations in the distribution system using EPANET, ES WTP was chosen. Free chlorine concentrations of several sites were less than the drinking water quality standards(i.e., 0.1 mg/L); E5(0.03 mg/L), E6(0.02 mg/L), W21(0.02 mg/L) and W25(0.03 mg/L). To maintain more than 0.1 mg/L of free chlorine in the distribution system, at least 1.9 mg/L of chlorine was needed at the WTP, which suggested rechlorination was needed to supply palatable tap water to customers. Two sites, one that diverged into E5 and E6 in the east-line and another located before E21 in the west-line were selected for the appropriate rechlorination locations. The recommended rechlorination dosages were 0.42 mg/L for the east and 0.27 mg/L for the west. The simulated results indicated that the free chlorine could be reduced to 0.4 mg/L at the WTP with rechlorination, and taps with excessive free chlorine could be more stabilized(i.e., 0.1~0.4 mg/L).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.4
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• pp.265-270
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• 2002

Most of all the mechanical devices are becoming more high-speed and high-power as well as their used condition being more pollution with rapid development in industrial part. So, it is necessary for these devices to equip cooling system to overcome that kind of severe using condition. Industrial development and income increase causes rapid increase in using fossilenergy and it results in accelerating environmental pollution owing to the increasement in emission of air pollution substance. Specially, fresh water like stream and river water is acidified. Therefore, corrosion damage is accelerated in radiator for automobile that is using acidified water. So, in this study, corrosion test was carried out in distilled and tap water for the investigation on the corrosion behavior of Al-alloy that is using as material for radiator of automobile The main results obtained are as follows According to increase of temperature, open circuit potential is decreased in fresh water. And open circuit potential after deaeration is lower than that before deaeration. Corrosion current density in distilled water is less drained than that of tap water. And Corrosion current density after deaeration is less drained than that before deaeration.

• Journal of the East Asian Society of Dietary Life
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• v.27 no.1
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• pp.78-87
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• 2017

The objective of this study was to investigate the effects of various washing waters on the quality and safety characteristics of eggs during storage. Eggs were washed with tap water, 100 ppm of sodium hypochlorite, or 30 ppm of slightly acidic electrolyzed water and stored at $10^{\circ}C$ and $20^{\circ}C$. Effects of various washing waters on reduction of Salmonella Enteritidis and aerobic plate counts and survival of S. Enteritidis on egg shells were also analyzed at $10^{\circ}C$ and $20^{\circ}C$ for 25 days. As an index of quality, haugh unit, weight reduction, and pHs of egg white and egg yolk were measured. Reduction percentages of haugh unit and weight were higher at $20^{\circ}C$ than at $10^{\circ}C$. Egg qualities were less affected by tap water, slightly acidic electrolyzed water, and sodium hypochlorite, regardless of storage temperature. The greatest reductions in aerobic plate counts and S. Enteritidis were observed with slightly acidic electrolyzed water. The level of S. Enteritidis on egg shells gradually decreased during 20 days of storage at both $10^{\circ}C$ and $20^{\circ}C$, whereas S. Enteritidis survived longer at $20^{\circ}C$ than at $10^{\circ}C$. S. Enteritidis was not detected in eggs at $10^{\circ}C$, 2.13 log CFU/g of S. Enteritidis was detected in eggs washed with sodium hypochlorite after 20 days of storage at $20^{\circ}C$, indicating that S. Enteritidis penetrated into the egg shell during storage at $20^{\circ}C$. In conclusion, slightly acidic electrolyzed water increased microbial reduction and least affected quality of washed eggs. Thus, slightly acidic electrolyzed water can be recommended for washing of graded eggs, at retail markets.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.28-34
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• 2006

Effects of various surface sterilization and washing methods on sterilization of fresh chicory surface were evaluated. Fresh-cut chicory was washed with tap water for 1 min, 100 ppm chlorinated water, and 3 ppm ozonated water using mechanical washing machine for 3 min, packed with bi-axially oriented polypropylene (OPP 0.04 mm) film, and stored for 3 weeks at 4 and $10^{\circ}C$. Tap water washing resulted in approximately 1 log CFU/g reduction of microbial load, and ozonated water and chlorinated water treatments resulted in additional 2 log CFU/g reduction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.322-323
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• 2022

The most necessary thing for the optimal operation of a water purification plant is to accurately predict the pattern and amount of tap water used by consumers. The required amount of tap water should be delivered to the drain using a pump and stored, and the required flow rate should be supplied in a timely manner using the minimum amount of electrical energy. The short-term demand forecasting required from the point of view of energy optimization operation among water purification plant volume predictions has been made in consideration of seasons, major periods, and regional characteristics using time series analysis, regression analysis, and neural network algorithms. In this paper, we analyzed energy management methods through AI-based complex sensor applicability analysis such as LSTM (Long Short-Term Memory) and GRU (Gated Recurrent Units), which are types of cyclic neural networks.

• Journal of Environmental Health Sciences
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• v.38 no.6
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• pp.503-509
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• 2012

Objectives: This study was performed in order to evaluate the generation characteristics of airborne bacteria and fungi while operating a household humidifier, in consideration of user habits. Methods: Microbial samples were collected in a closed chamber with a total volume of 2.76 $m^3$, in which a humidifier was operated according to experimental strategies. A cultivation method based on the viable counts of mesophilic heterotrophic bacteria and fungi was performed. Experimental strategies were divided into three classes: the type of water in the water reservoir (tap water, cooled boiled water); the frequency of filling the reservoir (refill every day, no refill); and the sterilization method (sterilization function mode, humidifier disinfectants). Results: Significant increases in the concentration of airborne bacteria were observed while the humidifier was in operation. The concentration had increased to 2,407 $CFU/m^3$ by 120 hours when tap water filled the reservoir without any application of sterilization, while for cooled boiled water, it was merely 393 $CFU/m^3$ at a similar time point. Usages of disinfectant in the water tank were more effective in decreasing bioaerosol generation compared to sterilization function mode operation. Generation characteristics of airborne fungi were similar to those of bacteria, but the levels were not significant in all experiments. Calculated exposure factor can be used as an indicator to compare biorisk exposure. Conclusion: This study identified the potential for bioaerosol generation in indoor environments while operating a household humidifier. User practices were critical in the generation of bioaerosol, or more specifically, airborne bacteria. Proper usage of a humidifier ensures that any biorisks resulting from generated bioaerosol can be prevented.

• The Journal of the Petrological Society of Korea
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• v.22 no.1
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• pp.63-70
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• 2013

We report an easy and efficient method for separating zircon grains using a gold pan and disposable sieve together with the tap water. Samples powdered to less than $230{\mu}m$ in grain size are placed on the water-filled pan tilted at about $10^{\circ}$. The outflowing water flooded with low-density particles is screened by a ${\sim}70{\mu}m$ sieve. The most efficient rate of water outflow is estimated to be 0.1 L/sec, when the distance between the tap and the surface of water-filled pan is kept at 20-25 cm. After 20-30 minutes of water outflow, heavy mineral fractions are ready for zircon collection using a hand magnet (and heavy liquid when necessary) or simply hand-picking. This procedure is most likely applicable for the separation of other heavy minerals including monazite.

• Journal of the Korean Burn Society
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• v.24 no.1
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• pp.7-13
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• 2021

Purpose: Currently, the most recommended method for burn first aid is the cool running water for 20 minutes (CRW20). If CRW20 is not practicable, cooling dressing products with tea tree oil are used as substitutes. In this study, we analyze the effect of various burn first aids, including CRW20, cooling products, on the treatment period. Methods: This study was conducted on patients who suffered burns and visited Hangangsoo Hospital from March 2019 to March 2020. The study conducted in a retrospective method. The duration of treatment was analyzed by dividing the experimental group. Results: The treatment period was shortened when first aid was given (P<0.001). Cold water, ice, and ice packs resulted in reduced treatment periods (P<0.001, P=0.004). The treatment period was reduced when cooling dressing products were used in all groups (P=0.041). The implementation of first aid has reduced the duration of burn treatment. This means that cooling helps burn treatment. CRW20 did not show statistically meaningful results. This is the result of a failure to fully control the temperature and time of tap water. In addition, the change in temperature of tap water according to season, the use of water is higher than that of animal testing, and the general lack of information on proper burn first aid may have affected. Conclusion: The treatment period was statistically significantly reduced in the group that performed first aid. Among the various first aid methods, cold water and ice reduced the treatment period.