• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.794-795
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• 2006

Metal powder for dust core application was developed. The powder can be produced improved high-pressure water atomization process. The process has produced powder of spherical shape and lower coercivity. The dust core obta ined shows lower core loss.

• Membrane and Water Treatment
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• v.3 no.3
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• pp.181-200
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• 2012

At present water crisis is not an issue of scarcity, but of access. There is a growing recognition of the need for increased access to clean water (drinkable, agricultural, industrial use). An encouraging number of innovative technologies, systems, components, processes are emerging for water-treatment, including new filtration and disinfectant technologies, and removal of organics from water. In the past decade many methods have been developed. The most important membrane-based water technologies include reverse osmosis (RO), ultrafiltration (UF), microfiltration (MF), and nanofiltration. Beside membrane based water-treatment processes, other techniques such as advanced oxidation process (AOP) have also been developed. Some unconventional water treatment technology such as magnetic treatment is also being developed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.22-23
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• 2006

A process for removal of photoresist(PR) m semiconductor manufacturing using water vapor with ozone is presented. For the realization of the ozone/vapor mixture process, high concentration ozone generator and process facilities have developed. As a result of the silicon wafer PR strip test, we confirmed the high efficiency PR strip rates of 400nm/mm or more at the ozone concentration of 16wt%/$O_2$. The ozone/vapor mixture process is more effective than the ozonized water Immersion process.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.610-614
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• 2004

The objective of this study was to remove organics and color in livestock wastewater using coagulation and Fenton oxidation process. After coagulation process as $1^{st}$ treatment, organics in $1^{st}$ treatment water were removed by using OH radical produced in Fenton oxidation process. Removal efficiencies of $COD_{Mn}$ and color were 87.2% and 95.7% separately. At that time, the ratio of $Fe^{2+}/H_2O_2$ was 0.8~1.0, and range of reaction pH was effective at the pH of 3.5~3.8. The Reaction time of 120min more than 60min or 90min was sufficient in Fenton process. Removal efficiency of organics was higher two- or multi-stage treatment than one-stage treatment.

• Journal of Korean Society of Rural Planning
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• v.28 no.3
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• pp.49-59
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• 2022

Recently, Korea aimed to increase water use efficiency by implementing integrated management according to the water management unification policy. Considering the enormous use of water resources in the agricultural sector, it is necessary to efficiently conserve water in terms of demand management by intensifying the stakeholders' involvement and awareness campaigns. The existing agricultural water management system in Korea is based on a top-down approach by which the government agencies directly plan budgets and policies to be enforced on and implemented by farmers, with little to no involvement of farmers in the decision-making process. However, this process has hindered the desired water resources management and the water conservation goal at the field level. Moreover, the limited research on water governance operations focusing on agricultural water creates a knowledge gap, particularly in Korea. Thus, it is necessary to investigate water governance cases with successful implementations in agricultural and rural areas to identify the factors applicable to domestic governance in Korea. In addition, a more systematic governance model should be established by identifying the subjectivity of the stakeholders' involvement in agricultural water governance. Therefore, this study proposed a new bottom-up model for agricultural water governance, which aims to raise the problem of autonomous water governance while promoting stakeholders' voluntary participation in agricultural water management and reflecting farmers' involvement in the decision-making process. Moreover, if agricultural water governance is expanded nationwide by reflecting agricultural and water resource policies in the future, it is believed that positive effects can be achieved in increasing utilization efficiency and securing sustantiality through agricultural water saving.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.1-10
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• 2018

Recently, interest in the development of alternative water resources has been increasing rapidly due to environmental pollution and depletion of water resources. In particular, seawater desalination has been attracting the most attention as alternative water resources. As seawater desalination consumes a large amount of energy due to high operating pressure, many researches have been conducted to improve energy efficiency such as energy recovery device (ERD). Consequently, this study aims to compare the energy efficiency of RO process according to ERD of isobaric type which is applied in scientific control pilot plant process of each $100m^3/day$ scale based on actual RO product water. As a result, it was confirmed that efficiency, mixing rate, and permeate conductivity were different depending on the size of the apparatus even though the same principle of the ERD was applied. It is believed that this is caused by the difference in cross-sectional area of the contacted portion for pressure transfer inside the ERD. Therefore, further study is needed to confirm the optimum conditions what is applicable to the actual process considering the correlation with other factors as well as the factors obtained from the previous experiments.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.279-284
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• 2016

Membrane distillation (MD) is the thermally driven water separation process based on the vapor pressure difference across the membrane. In order to increase the water recovery of the conventional RO process, the additional MD-PRO pocess was suggested. In this study, the syntheric RO brine was used as a feed solution of the MD process. Due to the high salinity of the RO brine, the MD membrane could be fouled by the scalants. In order to mitigate the scaling on the MD membrane surface, the pre-treatment process using the column filled by natural zeolite was applied. The roughing filter was installed between the pre-treatment process and MD system in order to prevent possible particulate fouling by the debries of the natural zeolite. Moreover, in order to enhance the CEC of the natural zeolite, the NaCl soaking was conducted. The flux and electronic conductivity were monitored under given experimental conditions. And the membrane morphology and the chemical compositions were analyzed by using the SEM-EDX.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.6
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• pp.644-651
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• 1997

In the water purification plant, chemicals are injected for quick purification of raw water. It is clear that the amount of chemicals intrinsically depends on water quality such as turbidity, temperature, pH and alkalinity. However, the process of chemical reaction to improve water quality (e.g., turbidity) by chemicals is not yet fully clarified nor quantified. The feedback signal in the process of coagulant dosage, which should be measured (through the sensor of the plant) to compute the appropriate amount of chemicals, is also not available. Most traditional methods focus on judging the conditions of purifying reaction and determine the amounts of chemicals through manual operation of field experts using Jar-test data. In this paper, a systematic control strategy is proposed to derive the optimum dosage of coagulant, PAC(Polymerized Aluminium Chloride), using Jar-test results. A neural network model is developed for coagulant dosing and purifying process by means of six input variables (turbidity, temperature, pH, alkalinity of raw water, PAC feed rate, turbidity in flocculation) and one output variable, while considering the relationships to the reaction of coagulation and flocculation. The model is utilized to derive the optimum coagulant dosage (in the sense of minimizing turbidity of water in flocculator). The ability of the proposed control scheme validated through the field test has proved to be of considerable practical value.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.580-584
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• 2010

As water becomes more scarce around the world the reuse of treated wastewater is being recenlty considered as indispensible trend we need to follow. Especially, industrial area consuming large amount of water has been encouraged to reuse the treated wastewater to secure sufficient water for the production of merchandise. In this study, a study of advanced oxidation process for treatment of industrial wastewater. The treatment performance of UV and ozoznation and five types advanced oxidation processes such as UV/AC, UV/Catalyst, $O_3$/Catalyst, UV/$O_3$/Catalyst was experimentally investigated for reuse of industrial wastewater. The removal efficiency of $COD_{Cr}$, color were relatively evaluated in each treatment unit simulated outflow water of wastewater treatment area. UV/$O_3$/Catalyst process showed the highest $COD_{Cr}$ remaval and color remaval among proposed oxidation process.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.2
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• pp.267-274
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• 2008

This study is about efficiency of pretreatment process and operating factor to membrane process at continuous coagulation/ultrafiltration process in water treatment. The capacity of pilot plant was $0.06{\beta}(C)/d$. The raw water used was from Nakdong stream which was characteristized by high organic matter and high turbidity. The result of the test was that coagulation is good process as to high removal rate to organic matter and turbidity but It caused problem to membrane pore blocking. This paper is to determine the membrane fouling potential under different membrane flux, backwash pressure and linear velocity. Backwash pressure and flux is important parameter on operation of membrane system. Those are directly affected on membrane system. When backwash pressure increased from 150 kPa to 200 kPa, the result showed that fouling (pressure increase rate) changed from 3.69 kPa/h to 0.93 kPa/h and the recovery rate changed from 90.7 % to 82.0 %. Linear velocity had slightly effect on fouling. Linear velocity increased from 0.2 m/s to 0.5 m/s, the corresponding pressure rate changed from 0.93 kPa/d to 0.77 kPa/d.