• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.137-142
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• 1999

Current semiconductor industry factories are relying on the end-of-pipe treatment technology for waste water treatment and thus they mostly suffer from severe industrial water shortage. As a result in order to solve those waste and industrial water problems, there requires to be changed to the Clean Technology, that is Pollution Prevention Technology. Through above strategic actions with the Clean Technology, we shall strength more powerful and logical environmental pollution prevention system than those in the past. By changing the end-of-pipe treatment technology for waste water treatment and thus they mostly suffer from severe industrial water problems, there requires to be changed to the Clean Technology, that is Pollution Prevention Technology. Through above strategic actions with the Clean Technology, we shall strength more powerful and logical environmental pollution prevention system than those in the past. By changing the end-of-pipe treatment technology with physical, chemical and biological treatment methods as a mixed stream basis for treating of semiconductor waste stream into clean technology with pollution prevention technology as a waste segregation basis, we can bet 20 to 30% investment reduction as compared with end-of-pipe treatment technology.The results for water quality analysis were as follows : 1. Water quality analysis of the before treatment : pH : 9~10.5, Conductivity : $300~7,000{\mu}s/cm$, TDS : more then $3,000mg/{\ell}$, COD : $200~250mg/{\ell}$, SS : $500~600mg/{\ell}$, n-H : $8.3mg/{\ell}$ 2. Water quality analysis of the after treatment : pH : 6.5~7.5, Conductivity : 0.059, TDS : $40{\mu}s/cm$, COD : $20mg/{\ell}$, SS : $5mg/{\ell}$ n-H : $0.6mg/{\ell}$

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.596-604
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• 2020

Solid oxide electrolysis cell (SOEC) attracts much attention because of its high energy efficiency among many water-electrolysis technologies. SOEC operates at temperatures above 700℃, so that the water required for water-electrolysis must be supplied in the form of steam. When the steam to be supplied to the SOEC is generated by the SOEC system itself, an enormous amount of latent heat is required to vaporize the water, so additional energy must be supplied to the SOEC system. On the other hand, if the steam can be supplied from the outside, a small amount of energy is required to raise the temperature of the low temperature steam, so that the SOEC system can be operated without additional energy supply from outside, which enables efficient water-electrolysis. In this study, we figure out the size of heat exchanger for various steam temperature and effectiveness of heat exchanger, and propose the energy efficiency of the system.

• Corrosion Science and Technology
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• v.21 no.5
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• pp.327-339
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• 2022

The water-jet technique started by Bridgman can cut metal and alloys without harmful gas and fume. However, while this technique is convenient to cut metals and alloys, in the case of coated pipe, water jet induces the degradation of coatings on the pipes, and may facilitate structural failure, leakage, and loss of products. While there are many reports on the effect of water jet on cut metals and the damage of metallic materials, research on the effect of water impingement on the epoxy coatings has been little studied. In this work, we therefore control the velocity of water jet, distance between nozzle and specimen, and water temperature, and discuss the effect of water impingement on the epoxy coatings. Increasing water velocity and water temperature and reducing nozzle distance increased the degradation rates of three epoxy coatings were increased. Among three test parameters - water velocity, nozzle distance and water temperature, water temperature was relatively effective to increase the degradation rate of epoxy coatings.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.5
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• pp.101-106
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• 2009

The previous study developed the Filter-Disinfection-Adsorption (FDA) system to provide clean irrigation water for greenhouse cultivation as well as convenience water to farmers. In this study, the field examination was undertaken to assess performance of the FDA system. The field application was made in the suburb of Daegu, one of the large city in Korea. The study area located near by down-stream of Gum-Ho river is suffering low irrigation water quality problems with no water supply service facilities. Four water quality parameters including Suspended Solid (SS), Biological Oxygen Demand (BOD), coliform, and turbidity were selected to test the purification performance of FDA system. Also in order to improve the system, this study investigated the defects of using the FDA system through field monitoring. As results, it was found that this system can be used to supply good quality of irrigation water for greenhouse cultivation and also provide convenience water to farmers in the field areas of no water supply services.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.15-20
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• 2009

The concentration of residual chlorine should be kept at over 0.1 mg/L in the circular water tank used in a water purification system. Generally, the concentration of residual chlorine depends on the structure and the volume of water tank, and also the water flow rate. To secure the diffusion time is important to the concentration of residual chlorine. For that reason, the baffles are installed in the circular water tank. In the present study, the variations of water and chlorine concentration were obtained with time using the numerical analysis. And also, the streamlines were shown according to the number of baffles. As a results, the vortex flow appeared between baffles, and the diffusion time of chlorine increased with the more number of baffles.

• Rapid Communication in Photoscience
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• v.4 no.4
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• pp.82-85
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• 2015

Photoelectrochemical cell (PEC) is one of the attractive ways to produce clean and renewable energy. However, solar to hydrogen production via PEC system generally requires high external bias, because of material's innate electronic band potential relative to hydrogen reduction potential and/or charge separation issue. For spontaneous photo-water splitting, here, we design dye-sensitized solar cell (DSSC) and their monolithic tandem cell incorporated with a $BiVO_4$ photoanode. $BiVO_4$ has high conduction band edge potential and suitable band gap (2.4eV) to absorb visible light. To achieve efficient $BiVO_4$ photoanode system, electron and hole mobility should be improved, and we demonstrate a tandem cell in which $BiVO_4/WO_3$ film is connected to cobalt complex based DSSC.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.129-139
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• 2010

Coal gasification process, which had developed originally to convert coal from hydrogen and carbon monoxide, has used and developed in many countries because of environmental advantages such as carbon dioxide storage, decrease of pollutants and so on. Generally entrained-flow gasification process using pulverized coal under $75{\mu}m$ is used in Integrated Gas Combined Cycle(IGCC) because of easy scale up and high efficiency of energy conversion. Especially entrained-flow gasifers with coal water slurry have been used in many applications due to its fully developed technologies. In this paper, several technologies for coal-water slurry gasification that involves slurry preparation, burner, gasifier, slag melting and numerical simulation for plant design and operation were investigated. Entrained-flow gasification with coal water slurry can be used for synfuel production, SNG, chemicals as well as IGCC. To develop hybrid gasification process and use different types of coal, it is necessary to develop new technologies that will increase efficiency of the process.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.5
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• pp.95-100
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• 2009

The water purification systems have been hardly used for agricultural purpose due to their complicated compositions and high costs for farmers, while only simple filtrations have been applied to irrigation systems in order to prevent the system from clogging problems. This study therefore developed a clean water supplying system, the Filter-Disinfection-Adsorption (FDA) system, especially for greenhouse cultivation of where low quality of water is available. This system has also been produced for providing convenience water to farmers in the areas of no water supply service systems for the purpose of washing their bodies or agricultural machineries after farm work. The FDA system consists of three stages of purification processes with an integral module, including disk and teflon filtrations and Ultraviolet (UV) sterilization processes. Indoor experiments were undertaken with a trial product of the FDA system to test its performance. The operation test of the process was performed as well as the condition check of each item including UV module, filters, control panel, pump, valves, etc. The results shows good performance of each test with no critical problems. The initial and maintenance costs were also analysed with other purification systems. From the comparisons, the FDA system found to be very economical and easy to use.

• Membrane and Water Treatment
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• v.2 no.1
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• pp.1-24
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• 2011

The deficiency of clean water is a major global concern because all the living creatures rely on the drinkable water for survival. On top of this, abundant of clean water supply is also necessary for household, metropolitan inhabitants, industry, and agriculture. Among many purification processes, advances in low-energy membrane separation technology appear to be the most effective solution for water crisis because membranes have been widely recognized as one of the most direct and feasible approaches for clean water production. The aim of this article is to give an overview of (1) two new emerging membrane technologies for water reuse and desalination by forward osmosis (FO) and membrane distillation (MD), and (2) the molecular engineering and development of highly permeable hollow fiber membranes, with polyvinylidene fluoride (PVDF) and polybenzimidazole (PBI) as the main focuses for the aforementioned applications in National University of Singapore (NUS). This article presents the main results of membrane module design, separation performance, membrane characteristics, chemical modification and spinning conditions to produce novel hollow fiber membranes for FO and MD applications. As two potential solutions, MD and FO may be synergistically combined to form a hybrid system as a sustainable alternative technology for fresh water production.

• Journal of Institute of Convergence Technology
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• v.4 no.2
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• pp.61-65
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• 2014

Pressure distribution around rotating impeller blades in centrifugal pump has been main issue for design of efficient and high performance automotive water pump. In addition, pressure losses of inlet water pipes should be considered to reduce additional pressure drop and design high performance engine cooling system. In this paper, pressure distribution inside water pump and pressure drop between inlet and outlet of water pump are investigated numerically to design plastic water pump for clean diesel engine application. And the inlet geometry of water pump was considered to analysis the effect of inlet water pipe geometry on pressure distribution around impeller blades and outlet pressure. The prediction results are compared with experimental data to validate and determine optimal operation condition without water pump cavitation. Major design parameters such as blade angle, volute geometry, system pressure, and coolant flow rate are considered to confirm applying possibility of plastic blades to the clean diesel engine.