• Journal of the Korean Society of Food Science and Nutrition
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• v.11 no.3
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• pp.67-74
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• 1982

The effect of various pH levels, temperatures. organic acids, inorganic salts, metal ions on the stability of the anthocyanins pigment (pH 3.7) from the juice of raspberries were investigated. Initial absorption of total anthocyanin was decreased as pH increased from 1.0 to 7.0. Total amount of anthocyanin reached the highest at pH 3.7 and least at pH 7.0. The total anthocyanin content decreased rapidly with the increasing temperature. Many organic acids were found to enrich and stabilize the color density at 520nm in anthocyanin solution (pH 3.7). The hyperchromic effect of saturated n-carboxylic acid increased in the following order; formic acid> acetic acid>n-butyric acid>propionic acid. On the polycarboxylic acid, especially, malic acid showed 550$\sim$930% higher than control group. On the inorganic salts (0.5M), sodium perchlorate had the most hyperchromic effect and followed by sodium sulfate>sodium chloride>sodium phosphate, monobasic. Among the metal ions, both aluminium ion and cupric ion much more accelerated the anthocyanins degradation as compared with other metal ions.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.535-541
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• 2017

On the basis of 200 ppm of Ag and 120 l/h of feed flow rate, we built a pilot plant of an ion exchange fiber system having an double tube type ion exchange chamber with strong base ion exchange fiber (FIVAN A-6) which was designed to replace fibers easily and to eliminate the need for a fixture. The following results were obtained for the double tube type of ion exchange fiber system with an ion exchange capacity of 4.6 meq/g for Ag. The adsorption process was operated in the range of 40~90 l/h after confirming the effect of the flow rate and, pH did not affect formation of complex ion of Ag in the range of pH 7~12. In the case of backwash process, the recovery rate of Ag was tested in the range of 60~120 l/h and comparative experiments were carried out using NaOH, $NH_4Cl$, and NaCl as the chemicals for backwash. Although the desorption time was shortened at higher concentration, the desorption efficiency per mol was lowered. Therefore, it was confirmed that the desorption time and the concentration should be well balanced to operate economically. The desorption pattern of the backwash process is slower than the adsorption process and takes a lot of time. The results showed that the Ag adsorption ratio was 99.5% or more and the Ag recovery ratio was 96% or more, and commercialization was possible.

• Polymer(Korea)
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• v.30 no.6
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• pp.568-571
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• 2006

Poly(vinyl alcohol) (PVA)/gelatin(GEL) blend membranes were prepared under a high electric field, and their swelling and ion permeation behaviors were investigated. For alkali metal salts such as LiCl, NaCl and KCl, the permeability coefficients were increased until the electric field of 10 kV due to the decreased tortuosity, whereas they were decreased over 10 kV owing to the increase of the degree of crystallinity. The swelling ratios of the blend membranes showed the minimum values at pH 6, while the permeability coefficients exhibited the maximum values at the same condition. The minimum swelling ratios result from the repulsion effect between charged groups in acidic or basic regions, and the maximum permeabilities result from Donnan exclusion effect in the same regions. Especially, the per-meability coefficient for KCl of the membrane increased steeply to five times at $40^{\circ}C$ than below $35^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.665-671
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• 2017

The alkali-Metal Thermal-to-electric Converter (AMTEC) is one of the promising static energy conversion technologies for the direct conversion of thermal energy to electrical energy. The advantages over a conventional energy converter are its high theoretical conversion efficiency of 40% and power density of 500 W/kg. The working principle of an AMTEC battery is the electrochemical reaction of the sodium through an ion conducting electrolyte. Sodium ion pass through the hot side of the beta"-alumina solid electrolyte (BASE) primarily as a result of the pressure difference. This pressure difference across the BASE has a significant effect on the overall performance of the AMTEC system. In order to build the high pressure difference across the BASE, hermeticity is required for each joined components for high temperature range of $900^{\circ}C$. The AMTEC battery was manufactured by utilizing robust joining technology of BASE/insulator/metal flange interfaces of the system for both structural and electrical stability. The electrical potential difference between the anode and cathode sides, where the electrons emitted from sodium ionization and recombined into sodium, was characterized as the open-circuit voltage. The efforts of technological improvement were concentrated on a high-power output and conversion efficiency. This paper discusses about the joining and performance of the AMTEC systems.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.121-129
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• 1984

The adsorption characteristics of heavy metal ions $(Ni^{2+}$, $Zn^{2+}$) on domestic activated carbon which manufactured from the wood, waste rubber and coal has been studied. The following conclusions were obtained by investigating the effect of pH, halides, cyanide and temperature on the absorption of heavy metal ions and by determining absorption rate and absorption isotherms. When heavy metal ions were adsorbed on activated carbon in the pH range from 6 to 7, treated heavy metal ions were almost come to the equilibrium and recovered in the form of complex anions such as $MX_4^{2- }$and $M(CN)_4^{2-}$ in an hour. The absorption isotherms of heavy matel ions were well fitted in Freundlich's equation. Heavy metal complex anions on activated carbon were easily eluted by using 0.1N HCl solution. These results suggest that the complex anions have unexpectedly strong affinity for the surface of activated carbon.

• Economic and Environmental Geology
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• v.28 no.3
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• pp.231-241
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• 1995

It is well known that hydroxyapatite [$Ca_{10}(PO_4)_6(OH)_2$] have an exchangeability for various heavy metal ions in aqueous solution. To evalute the feasibility of employing the synthetic hydroxyapatites as an eliminatable exchanger for environmentally noxious caions in waste water, the adsorption properties, the removal capacities and the selectivity of the apatites for various cations were investigated in more detailed. The heavy metal cations have been exchanged in calcium part of hydroxyapatite. The order of the degree of amount exchanged of the investigated cations is $Pb^{2+}>Cd^{2+}>Zn^{2+}>Ba^{2+}$. The molar ratios between released $Cd^{2+}$ ions and remeved divalent metal cations in the reacted solution with hydroxyapatite are roughly close to an integer 1.0, suggesting that an ion-exchange reaction could have played a major role in the removal of heavy metals rather then an adsorption effect. The exchangeability of the hydroxyapatite powder of Ca/P molar ratio 1.67, which have specipic surface area of $104.5m^2g^{-1}$, appeared to be better then $237.6{\mu}g$ per g for $Pb^{2+}$ ions. The removal capacity of the heavy metal ions varies directly as particle size of hydroxyapatites. All evidences obtained indicate that the synthesized hydroxyapatite powders by precipitation reaction method can be employed as an effective cation exchanger for eliminating noxious ions in waste water even in some improvemental.

• Corrosion Science and Technology
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• v.5 no.1
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• pp.15-22
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• 2006

The introduction of two-grid inside a conventional process system produces a reactive coating deposition and increases metal ion ratio in the plasma, resulting in denser and smoother films. The corrosion behaviors of TiN coatings were investigated by electrochemical methods, such as potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in deaerated 3.5% NaCl solution. Electrochemical tests were used to evaluate the effect of microstructure on the corrosion behavior of TiN coatings exposed to a corrosive environment. The crystal structure of the coatings was examined by X-ray diffractometry (XRD) and the microstructure of the coatings was investigated by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). In the potentiodynamic polarization test and EIS measurement, the corrosion current density of TiN deposited by two grid-attached magnetron sputtering was lower than TiN deposited by conventional magnetron type and also presented higher Rct values during 240 h immersion time. It is attributed to the formation of a dense microstructure, which promotes the compactness of coatings and yields lower porosity.

• Journal of the Korean institute of surface engineering
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• v.53 no.5
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• pp.207-212
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• 2020

Silver is an inexpensive precious metal and is used in various jewelry in Asia. Although silver has high potential, it has corrosion resistance that is vulnerable to boiling sulfuric acid and nitric acid. So, silver research is needed to prevent the corrosion with environment. But silver corrosion is not studied. sulfuric acid make the uniform corrosion and chloride ion make the pitting corrosion. ICCP inhibits the corrosion because it offset electrons. This study used a potential from - 4 V to 4 V to check the effect of potential. Corrosion rate is lowet at -1 V.

• The Korean Journal of Pharmacology
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• v.19 no.2
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• pp.35-44
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• 1983

reactive oxygen species에 의해 나타나는 reactivity에 있어서 metal ions이 관여함이 시사되고 있다. 이미 알려진 reactive oxygen species와 metal ions의 상호작용 이외에 특히 $Cu^{++}$과 $H_2O_2$가 강력한 peroxidative action을 나타낸다는 사실이 알려져 있으며 $Cu^{++}-H_2O_2$가 biological system 에서의 조직파괴에 관여할 가능성이 저자들에 의해서 효소 및 조직치 구조 단백질의 gradation 효과를 관찰함으로써 시사되었다. 본 연구는 $H_2O_2$ 혹은 $H_2O_2$를 생성하는 효소계(xanthine과 xanthine oxidase 및 glucose과 glucose oxidase)에 $Cu^{++}$을 첨가하여 $Cu^{++}-H_2O_2$에 의한 peroxidation의 효과를 collagen gelation을 통하여 확인코저 수행하였으며 다음과 같은 결과를 얻었다. 1) $Cu^{++}(20\;{\mu}M)$과 $H_2O_2$에 의하며 collagen gelation은 현저히 억제되었으며 이같은 억제효과는 양자의 농도에 비례하였다. 2) $Cu^{++}-H_2O_2$ reactivity를 확인하는 다른 방법으로 glucose oxidase system를 이용하였다. glucose oxidase$(2.5{\mu}g/ml)$ 와 glucose(0.5 mM)는 collagen gelation에 영향을 미치지 않았으나 이에 $Cu^{++}$이 존재하면 gelation이 억제되었다. 이때 억제정도는 $glucose(0.125{\sim}l.25\;mM)$와 $Cu^{++}$의 농도에 비례하였다. 3) 여러 reactive oxygen species 가운데 $Cu^{++}-H_2O_2$ reactivity를 xanthine oxidase system을 이용하여 확인하였다. (a) collagen gelation은 xanthine oxidase(30 munits/ml)와 xanthine$(0.25{\sim}2\;mM)$에 의하여 억제되었다. (b) 이때 나타나는 collagen gelation의 억제는 superoxide dismutase에 의하여 완전히 회복되었으나 catalase에 의해서는 더욱 촉진되었다. 그러나 catalase에 의한 억제효과의 촉진은 1,4-diazabicyclo(2,2,2)octane에 의하여 완전히 소실되었다. 따라서 이 xanthine oxidase system에서는 $O_2-,\;H_2O_2,\;^1O_2$이 관여함을 알 수 있었다. (c) 그러나 $Cu^{++}(10\;{\mu}M)$이 존재하였을 때 collagen gelation은 superoxie dismutase에 의해 더욱 억제되었고 catalase에 의해서는 완전히 회복되었다. xanthine oxidase계에서 얻어진 결과는 여러 reactive oxygen species가운데 $H_2O_2$가 $Cu^{++}$에 의하여 peroxidation효과를 나타냄을 알 수 있었다. 이상의 결과로 미루어 볼 때 reactive oxygen species와 metal ions과의 상호작용 가운데 $Cu^{++}-H_2O_2$는 강한 반응을 나타내는 특이한 구성요소이고 헌재 시사되고 있는 reactive oxygen species의 biological effects에 비추어 $Cu^{++}-catalyzed peroxidation$도 병적상태에서 생체에 유해한 작용을 나타내는 요소임을 시사하며 특히 염증시 조직파괴역할에 관하여 고찰하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1169-1174
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• 2011

CdTe thin-film solar cell technology is well known that it can theoretically improve its conversion efficiency and manufacturing costs compared to the conventional silicon solar cell technology, due to its optical band gap energy (about 1.45eV) for solar energy absorption, high light absorption capability and low cost requirements for producing solar cells. Although the prior studies obtained the high light absorption, CdTe thin film solar cell has not been come up to the sufficient efficiency yet. So, doping method was selected for the improvement of the electrical characteristics in CdTe solar cells. Some elements including Cu, Ag, Cd and Te were generally used for the p-dopant as substitutional acceptors in CdTe thin film. In this study, the sputtering-deposited CdTe thin film was immersed in $AgNO_3$ solution for ion exchange method to dope Ag ions. The effects of immersion temperature and Ag-concentration were investigated on the optical properties and electrical characteristics of CdTe thin film by using Auger electron spectroscopy depth-profile, UV-visible spectrophotometer, and a Hall effect measurement system. The best optical and electrical characteristics were sucessfully obtained by Ag doping at high temperature and concentration. The larger and more uniform diffusion of Ag ions made increase of the Ag ion density in CdTe thin film to decrease the series resistance as well as mede the faster diffusion of light by the metal ions to enhance the light absorption.