• Journal of the Korean Electrochemical Society
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• v.3 no.3
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• pp.136-140
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• 2000

A stainless steel separator for a molten carbonate fuel cell is usually coated with aluminum diffusive layer to protect its surface against corrosion by the molten carbonate at high temperatures. In this study, a relatively simple method was devised to form the aluminum diffusive layer on a stainless steel substrate. Slurry coating of aluminum on the substrate followed by heat treatment under reducing atmosphere at $650\~800^{\circ}C$ produced the aluminum diffusive layer of $25\~80{\mu}m$ thickness. The thickness of aluminum diffusive layer increased with increasing the temperature or duration of the heat-treatment. The corrosion resistance against molten carbonate under oxidizing atmosphere was significantly improved by aluminum diffusive layer formed by the sluny painting and heat treatment method. Moreover, the sample prepared in this study showed corrosion behavior similar to the sample with aluminum diffusive layer prepared by ion vapor deposition and heat treatment.

• Membrane Journal
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• v.15 no.1
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• pp.15-21
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• 2005

The integrally skinned asymmetric PAN ultrafiltration membranes were annealed for reducing the pore size. The effect of the chemical structure of two PAN polymers (homo- and copolymer) on annealing was investigated. The annealing of PAN polymer was strongly affected by the chemical structure of the polymer. In other words, the annealing effect of the copolymer was much larger than that of the homopolymer due to its less rigid structure of the main chain. Before annealing, the membranes were usually preheated in water in terms of the complete removal of remained solvents in the membranes. The annealing effect was bigger when no preheating. However, the preheating of the membrane before annealing at high temperatures leads to an increase in the pore size of membranes. The surface of the membranes was slightly negative and the salt rejection of PAN nanofiltration membrane was in the following order: R(Na₂SO₄) > R(NaCl) > R(MgSO₄) > R(CaCl₂). This salt rejection behavior could be explained by the Donnan equilibrium and the electroneutrality.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2205-2213
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• 2000

To investigate removal efficiency of dissolved matter by NF and RO, a pilot plant was operated for six months using groundwater treated by UF membrane. After the pilot plant operation, we performed autopsy test to identify characteristics of foulant attached on the membrane surface applying the used NF and RO in the pilot plant test. In autopsy test, we measured permeate flux and recovery rate of flux by chemical cleaning in each membrane. We also analyzed chemical cleaning disposal to examine component of foulant. Permeate flux of NF and RO1 showed rapid decline after 100 days of operation. Especially, reduction of specific flux in RO1 was more serious than in NF. Specific flux of RO2 with a low recovery rate resulted in gradual flux decline. Removal efficiencies of dissolved inorganic matters as a conductivity were 76.3%, 88.2% and 95.3% respectively for NF, RO1 and RO2, and RO2 presented the highest removal efficiency. And those of dissolved organic matters as TOC were about 80% for both NF and RO. The specific flux of membranes declined gradually from the feed water inlet to outlet of the membrane module and it showed that membrane fouling increased along the feed flow direction. Namely, concentration of pollutants became higher and volume of feed water was less as the feed flow approached to the outlet. It seemed that major foul ants were Ca consolidated into inorganic material and Si consolidated into organic material on the membrane surface. Fe was a great contribution to irreversible fouling. The SEM results indicated that the organic matter was attached to the first layer, closer to the membrane, and then inorganic matter with tetragonal shape layered over them. We could not observe biofouling because microorganism, which was cause of biofouling, was almost pretreated in UF membrane.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.327-332
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• 2021

Lithium-ion batteries (LIBs) have become a main energy storage device in various applications, such as portable appliances, renewable energy facilities, and electric vehicles. However, the poor thermal stability of LIBs may cause explosion or fire. The thermal runaway is the result of a failure of the separator inside LIB. Damages like tearing, piercing, and collapsing of the separator were simulated in a mechanical, an electrical, and a thermal way, and small discharge pulses of a few mV were detected at the time of separator damages. From the experimental results, this paper provided a method that can identify the separator failure before thermal runaway in the aspect of a potential explosion and fire prevention measures.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.810-815
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• 2011

Concentrated water discharged from seawater desalination process contains a high concentration of $Na^+$ ion. Electrolysis was applied to synthesize NaOH solution from the highly concentrated NaCl solution. The effect of various operating parameters of composited laboratory-scale chlor-alkali (CA) membrane cell was investigated. The operating parameters such as membrane types (CIMS and Nafion membranes), pretreatment of the membrane, flow rate (73 mL/min~200 mL/min), initial $Na^+$ ion concentration (1.5 M, 3M and 5 M) and current (1.5A and 2A) were evaluated. It was observed that synthesis efficiency of NaOH solution with CIMS membrane was higher than that with Nafion membrane, but the durability of CIMS membrane on $Cl_2$ gas was poor. The synthesis efficiency of NaOH solution increased with increasing initial $Na^+$ ion concentration and current, while the efficiency decreased with increasing flow rate using Nafion membrane.

• Korean Journal of Food Science and Technology
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• v.20 no.1
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• pp.90-94
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• 1988

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunodiffusion method were used for the species differentiation of yeasts, Saccharomyces cerevisiae, Candida utils, Candida tropicalis, and Kleuyveromyces fragilis. Comparing the electrophoretic patterns of soluble and membrane proteins, Saccharomyces cereνisiae was similar to Candida utilis but was different from Candida tropicalis and Kleuyveromyces fragilis. In immunochemical properties of soluble proteins, Saccharomyces cerevisiae was almost identical with Candido utilis. However, Saccharomyces cerevisiae or Candida utilis was quite different from Candida tropicalis and Kleuyveromyces fragilis in their immunoreactivities. In immunochemical properties of membrane proteins, almost the same results were obtained irrespective of four yeast species. By using SDS-PAGE and immunodiffusion methods, Saccharomyces cerevisiae and Candida utilis were difficult to differentiate but both species were easily differentiated from Candida tropicalis and Kleuyveromyces fragilis.

• Prospectives of Industrial Chemistry
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• v.23 no.1
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• pp.18-29
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• 2020

배터리 구동 기기의 사용이 계속적으로 증가하고 첨단화, 다기능화, 융합화가 되면서 고에너지 밀도 배터리에 대한 수요는 지속적으로 증가하고 있다. 배터리의 에너지 밀도를 높이는 여러 가지 전략 중에서 활물질 코팅 두께를 늘려 에너지를 저장하지 않는 집전체와 분리막의 사용량을 줄이고 배터리의 중량, 부피, 그리고 가격을 동시에 줄이는 전략은 간단하면서도 매우 효율적인 방법이다. 하지만 기존 전극 제작 방법으로 후막 전극을 제작할 경우 전극 제작 자체가 쉽지 않고 만들었다고 해도 전자와 이온의 두께 방향 이동 지연으로 인해 전극의 전기화학 특성이 좋지 않다. 이러한 문제점을 극복하고자 이차 전지용 첨단 후막 전극에 대한 연구가 활발하게 진행되고 있다. 본 기고문에서는 이차 전지용 후막 전극의 구조, 제조방법, 전기화학 특성에 관한 연구동향을 소개하고자 한다.

• Journal of the Korean Electrochemical Society
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• v.5 no.2
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• pp.62-67
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• 2002

The corrosion of the metallic cell components is blown to be one of the major reason f3r the performance degradation and subsequently the life-time limitation of the MCFC. To elucidate the corrosion phenomena, a corrosion study with the AISI-type 316L stainless steel, the most widely used separator material, in 621Li/38K carbonate eutectic melt was carried out. Corrosion phenomena in an MCFC were observed to differ from one location to another due to different environmental condition. The stability of passive film was found to be responsible fur the variations in corrosion phenomena. According to the potentiodynamic analysis, the passive film formed in anode-gas environment was less stable than in cathode-gas environment. The potentiostatic method combined with XRD analysis in addition to the cyclicvoltammetry was conducted to get an insight on variety corrosion reaction of AISI-type 316L stainless steel in a carbonate melt.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.227-238
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• 2013

The purpose of this study is to develop a process technology to produce high hardness drinking water which meet drinking water standard, remaining useful minerals like magnesium and calcium in the seawater desalination process while removing the sulfate ions and chloride ions. Seawater have been separated the concentrated seawater and desalted seawater by passing on Reverse Osmosis membrane (RO). Using Nano-filtration membrane (NF), We were prepared primary mineral concentrated water that sodium chloride were not removed. By the operation of electro-dialysis (ED) having ion exchange membrane, we were prepared concentrated mineral water (Mineral enriched desalted water) which the sodium chloride is removed. We have produced the high hardness water to meet the drinking water quality standards by diluting the mineral enriched desalted water with deionized water by RO. Reverse osmosis membranes (RO) can separate dissolved material and freshwater from seawater (deep seawater). The desalination water throughout the second reverse osmosis membrane was completely removed dissolved substances, which dissolved components was removed more than 99.9%, its the hardness concentration was 1 mg/L or less and its chloride concentration was 2.3 mg/L. Since the nano-filtration membrane pore size is $10^{-9}$ m, 50% of magnesium ions and calcium ions can not pass through the nano-filtration membrane, while more than 95% of sodium ions and chloride ions can pass through NF membrane. Nano-filtration membrane could be separated salt components like sodium ion and chloride ions and hardness ingredients like magnesium ions and calcium ions, but their separation was not perfect. Electric dialysis membrane system can be separated single charged ions (like sodium and chloride ions) and double charged ions (like magnesium and calcium ions) depending on its electrical conductivity. Above electrical conductivity 20mS/cm, hardness components (like magnesium and calcium ions) did not removed, on the other hand salt ingredients like sodium and chloride ions was removed continuously. Thus, we were able to concentrate hardness components (like magnesium and calcium ions) using nano-filtration membrane, also could be separated salts ingredients from the hardness concentration water using electrical dialysis membrane system. Finally, we were able to produce a highly concentrated mineral water removed chloride ions, which hardness concentration was 12,600 mg/L and chloride concentration was 2,446 mg/L. By diluting 10 times these high mineral water with secondary RO (Reverse Osmosis) desalination water, we could produce high mineral water suitable for drinking water standards, which chloride concentration was 244 mg/L at the same time hardness concentration 1,260 mg/L. Using the linked process with reverse osmosis (RO)/nano filteration (NF)/electric dialysis (ED), it could be concentrated hardness components like magnesium ions and calcium ions while at the same time removing salt ingredients like chloride ions and sodium ion without heating seawater. Thus, using only membrane as RO, NF and ED without heating seawater, it was possible to produce drinking water containing high hardness suitable for drinking water standard while reducing the energy required to evaporation.

• Clean Technology
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• v.13 no.4
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• pp.293-299
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• 2007

Direct coating of catalyst layer on the $Nafion^{(R)}$ membrane has been optimized in the process of fabrication of membrane electrode assembly (MEA) to enhance the performance of direct methanol fuel cell (DMFC). In this method, the contact resistance at the interface of the catalyst layer and the membrane was found to be low. The effect of catalyst loading, thickness of membrane and the gas diffusion layer (GDL) with or without the presence of micro-porous layer (MPL) on the performance of the MEA was also investigated. The MEA fabricated by the above-mentioned method exhibited a performance of $147\;mW/cm^2$ and $100\;mW/cm^2$ at $80^{\circ}C$ and $60^{\circ}C$, respectively, with the catalysts loading of $4\;mg/cm^2$.