• 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.

• Membrane and Water Treatment
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• v.5 no.2
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• pp.87-108
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• 2014

Electrodeionization (EDI), which combines electrodialysis (ED) and conventional ion-exchange (IX), is a mature process which has been applied since more than twenty years on commercial use for the production of ultrapure water (UPW). Eliminating chemical regeneration is the main reason for its commercial success. The increase in acceptance of EDI technology has led to an installation of very large plant as the commercial state of the art that produces $1,500m^3/h$ of water for high pressure steam boiler. More recently, EDI system has found a number of new interesting applications in wastewater treatment, biotechnology industry, and other potential field. Along with further growth and wider applications, the development of stack construction and configuration are also become a concern. In this paper, the principle of EDI process is described and its recent developments, commercial scale, and various applications are pointed out.

• Journal of Power Electronics
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• v.11 no.4
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• pp.612-619
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• 2011

This paper presents a water treatment system for leachate from sewage-filled ground that uses a pulsed-power modulator developed based on semiconductor switches in order to realize a long life, a high repetition rate, and a fast rising time. The specifications of the developed pulsed-power modulator are the pulsed output voltage, the output current, the pulse repetition rate (PRR), the pulse width, and an average output power of $60\;kV_{max}$, $300\;A_{max}$, 3000, $50\;{\mu}s$, and 15 kW, respectively. The pulsed-power water treatment system was introduced and analyzed using an equivalent electrical circuit model to optimize the output voltage waveform. The experimental results verify that the proposed water treatment system can be effectively used for industrial applications.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.6-13
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• 2018

Well-modified amino-appended ${\beta}$-cyclodextrin ($AA-{\beta}-CD$) with an amino group at the primary face of the ${\beta}-CD$ was synthesized and used in the catalytic synthesis of chromeno pyrimido[1,2-b]indazol as supramolecular catalysts in water for the first time. $AA-{\beta}-CD$ was characterized by FT-IR, NMR, MALDI-TOF mass spectrometry, and SEM analysis. A possible reaction mechanism featuring molecular complexation was suggested based on 2D NMR (ROESY) spectroscopy, FE-SEM, DSC, and FT-IR. Advantages such as operational simplicity, recyclability of the catalysts, and accessibility in aqueous medium render this protocol eco-friendly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2327-2331
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• 2011

The present paper relates to an analysis into patent applications by most exemplary patent-filing countries using time series analysis for a patented technology in which washing water in a water purifier is changed to magnetization hexagon water beneficial to human body, particularly the patented technology being to a magnetization hexagon water producing technology in which a magnetizer is mounted at an inlet pipe into which washing water is introduced to a water purifier, whereby the washing water is changed into magnetization hexagon water that is beneficial to human body for hygienic maintenance and use of bidet and toilet. In view of patent application trends in magnetization hexagon water producing technology fields, it can be easily noted from the analysis that a large portion of patent applications for the magnetization hexagon water producing technology comes from Korea and Japan, while USA and European countries are decreasing the number of patent applications and applicants. Therefore, there is a constant need of continuously observing the patent-filing trends in Korea and Japan in light of protection of patent rights in businesses that utilize the magnetization hexagon water. In view of the fact that many researches on and developments of products related to magnetization hexagon water are expected in the future, relevant producers and research institutes may effectively utilize the present paper in industrialization and patent research of the magnetization hexagon water.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.367-370
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• 2015

Monolayer transition metal dicalcogenide (TMDC) materials are currently attracting extensive attention due to their distinctive electronic, transport, and optical properties. For example, monolayer $MoS_2$ exhibits a direct band gap in the visible frequency range, which makes it an attractive candidate for the photocatalytic water splitting. For the photoelectrochemical water splitting, the appropriate band edge positions that overlap with the water redox potential are necessary. Similarly, appropriate band level alignments will be crucial for the light emitting diode and photovoltaic applications utlizing heterojunctions between two TMDC materials. Carrying out first-principles calculations, we here investigate how the band edges of $MoS_2$ can be adjusted by surface ligand functionalization. This study will provide useful information for the realization of ligand-based band engineering of monolayer $MoS_2$ for various electronic, energy, and bio device applications.

• Textile Coloration and Finishing
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• v.29 no.4
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• pp.202-210
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• 2017

In recent years, the water-based ink have been widely used in various industrial applications due to environmental problems. Dispersibility of the pigment for applications of the water-based ink is the one of the most important technical factors to produce uniform color products. Thus, in this study, the three-roll mill process was used to improve the dispersion of the water-based ink. The results indicated that the three-roll mill reduced the size of pigment particles in the ink more than 50%. In addition, the dispersant showed an important role to maintain the dispersion stability of the pigment in the water-based ink over 120 hours. We also confirmed the optimum contents of the ink stock solution, drying temperature and drying time by the colorimeter and colorfastness tests on produced PET synthetic suedes.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.394-394
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• 2009

Water solubility of conjugated polymers may offer many applications. Potential applications of water-soluble conjugated polymers include the polymer light-emitting diode and new materials for nano and micro hollow-capsules, and bio- or chemo-sensors. We synthesized neutral polyfluorenes containing bromo-alkyl groups by the palladium catalyzed Suzuki coupling reaction. Bromo-alkyl side groups in neutral polyfluorenes were quaternized by tri-methyl amine solution. The electrochemical and optical properties of water-soluble conjugated polymers are discussed. This novel synthesized water-soluble conjugated polymers were used as a interfacial dipole layer between active layer and metal cathode in polymer solar cell for enhancement of open-circuit voltage (Voc), which is one of the most critical factors in determining device characteristics. We also investigated the device performance of polymer solar cell with different metal cathode such as Al, Ag, Au and Cu. In polymer solar cell, novel cationic water-soluble conjugated polymers were inserted between active layer and high-work function cathode (Al, Ag, Au and Cu).

• Nuclear Engineering and Technology
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• v.43 no.3
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• pp.217-242
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• 2011

A variety of Generation III/III+ water-cooled reactor designs featuring enhanced safety and improved economics are being proposed by nuclear power industries around the world in efforts to solve the future energy supply shortfall. Thermal-hydraulics is recognized as a key scientific subject in the development of innovative reactor systems. Phase change by boiling and condensation in the reverse process is a highly efficient heat transport mechanism that accommodates large heat fluxes with relatively small driving temperature differences. This mode of heat transfer is encountered in a wide spectrum of nuclear systems,and thus it is necessary to determine the thermal limit of water-cooled nuclear energy conversion in terms of economic and safety. Such applications are being advanced with the introduction of new technologies such as nanotechnology. Here, we investigated newly-introduced nanotechnologies relevant to boiling and condensation in general engineering applications. We also evaluated the potential linkage between such new advancements and nuclear applications in terms of advanced nuclear thermal-hydraulics.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.91-91
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• 2011

In the present study, the proposed EMD and NSOR models has been applied in hydrology and climate sciences. Here, we present those applications as the following: (1) to extend future scenarios of Global Surface Temperature Anomaly including long-term oscillation component; (2) to extend the future evolution of the Eastern Canada winter precipitation; (3) to apply EMD in detecting climate change.