• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.4
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• pp.1-9
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• 2020

This study conducted to understand effects of CA (CaAl₂O₄) and CA₂ (CaAl₄O₇) ratio on chloride binding ability and compressive strength and pore structure of cement mortar incorporating mixture of CA and CA₂. The Portland cement based specimens were mixed with the clinkers CA and CA₂, and these calcium aluminate clinker mixture were replaced 0, 5, 10% by weight of cement. After all the test specimens were cured for 28 days under water curing, they were immersed in the distilled water and NaCl solution. As a result, 28 days compressive strength of all specimens was similar, and As the replacement ratio of calcium aluminate clinker in the specimen increased, Friedel's salt production tended to increase. However, it was dependent on the amount of Al₂O₃ in the level of 5% replacement and CA ratio in the level of 10% replacement. Through equilibrium isotherm result, it was also indicated that as replacement ratio of calcium aluminate clinker in cement matrix increased, chloride binding capacity was improved, and chloride penetration was suppressed. In this study, the specimen replaced with 10% of the calcium aluminate clinker mixture (CA 39%, CA₂ 60%) was remarkable to control chloride attack. We figured out necessity to understand optimal CA/CA₂ ratio to effectively apply CA₂ as a sustainable building material by improving the chloride binding ability in Portland cement based system.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.659-665
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• 2012

IgY (Immunoglobulin Yolk) in egg yolk corresponds to IgG (Immunoglobulin G) in animal serum and plays an important role as immunological proteins in intestines. Carrageenan and Arabic gum were used as pretreatment agents to purify IgY from fresh egg yolk. DEAE (Diethylaminoethyl) Sepharose column in FPLC (Fast Protein Liquid chromatography) was an ion exchange tool to remove contaminants as well as to elute IgY from the column. GF HPLC (Gel Filtration High Performance Liquid Chromatography) enables to measure the molecular weights of IgY and to identify the purified IgY by comparing the molecular weight of standard IgY with the purified one. IgY is a heterogeneous group of different molecular weight and ionic properties, which was investigated with various IE HPLC (Ion Exchange High Performance Liquid Chromatography) columns such as AX, CX and SCX. Three peaks of IgY were separated in the AX column under the conditions of 0.5 M NaCl and pH=8. The SCX column also gave the three peaks of IgY at 0.5 M NaCl and pH=5.

• Journal of Environmental Science International
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• v.21 no.4
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• pp.421-435
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• 2012

Novel $N_2O_2$ tetradentate ligands, H-3BPD and H-2BPD were synthesized. Hydrochloric acid salts of Br-3BPD, Cl-3BPD, Br-2BPD and Cl-2BPD having Br and Cl substituents at the $para$ position of the phenol hydroxyl group, were synthesized. The ligands were characterized by C. H. N atomic analysis, $^1H$ NMR, $^{13}C$ NMR, UV-visible, and mass spectra. The proton dissociation constants ($logK_n{^H}$) of the phenol hydroxyl group and secondary amine of the synthesized $N_2O_2$ ligands were shown by four step wise values. The orders of the calculated overall proton dissociation constants ($log{\beta}_p$) were Br-3BPD < Cl-3BPD < H-3BPD in case of 3BPD and Br-2BPD < Cl-2BPD < H-2BPD in case of 2BPD respectively. The order agreed well with that of $para$ Hammett substituent constants(${\delta}_p$). The stability constants($logK_{ML}$) of the complexes between the synthesized ligands and transition metal(II) ions agreed with the order of $log{\beta}_p$ of the ligands. The order of the $logK_{ML}$ value of the each transition metal (II) ion was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II), which agreed well with that of Iriving-Williams series.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1169-1178
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• 1998

This study was performed to purify fig pectinesterase(F-PE) and characterize its in situ activity. Three kinds of F-PE were partially separated by using ammonium sulfate fractionation, Q-Sepharose column, CM-cation exchanger column chromatography, and HPLC. One of those was anionic protein and the others were cationic proteins. All of them had approximate molecular weight of 27,000 and lost rapidly their activity during storage. Therefore alternative crude enzyme was prepared by suspending the freeze dried and milled fig powder in 0.1 M NaCl at pH 7.5. F-PE had the optimum pH of 8.5, the optimum temperature of $50^{\circ}C$ with activation energy of 7,671 cal $mol^{-1}K^{-1}$ and stability up to $55^{\circ}C$ with 10 minutes heating. Optimum activity was obtained in $0.2{\sim}0.4$ M NaCl with optimum solubility at above 0.8 M NaCl.

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.109-114
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• 2003

The electronic absorption spectra of trans-$[CrX_2([15]aneN_4)]ClO_4\;([15]aneN_4$=1,4,8,12-tetraazacyclopentadecane; X=F, Cl) complexes have been interpreted using the ligand field theory. An AOMX program is used to optimize the differences between the calculated and the observed positions for the spin-allowed transition bands. The crystal field theory(CFT) parameter is directly related to the angular overlap model(AOM), normalized spherical harmonic hamiltonians(NSH), and semiempirical parameters. The various ligand field parameters are discussed in terms of their chemical significances. According to the ligand field analysis, we can confirm that the fluoride ligand is a very strong ${\sigma}-$ and ${\pi}-$donor while the chloride has weak ${\sigma}-$ and ${\pi}-$donor properties toward chromium(III) ion.

• Journal of Life Science
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• v.8 no.5
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• pp.614-621
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• 1998

An extracellular inulinase from Penicillium sp. which isolated from soil sample was purified to a single protein th-rough ammonium sulfate fractionation, DEAE-Sephacel ion exchange chromatography and Toyopearl HW 65 F gel filtration. The temperature and pH for the enzyme reaction were around 6$0^{\circ}C$ and 4.0, respectively. The enzyme was stable at 3$0^{\circ}C$-5$0^{\circ}C$ and in the pH range of 4 to 5. $CuCl_2$, $HgCl_2$ and EDTA inhibited the enzyme activity strongly. By contrast, $MnCl_2$ and $CaCl_2$ activated the enzyme activity. The molecular weight of the purified enzyme was esti-mated to be 77,000 dalton by SDS-polyacrylamide gel electrophoresis. The Km values of the enzyme for inulin were calculated to be $2.2\times10^{-3}$M. TLC analysis suggested that purified enzyme is exo-type inulinase. The NH2-terminal amino acid sequences of the purified enzyme was determined to be $NH_2$-X-Glu-Ser-Tyr-Thr-Glu-Lys/Leu-Tyr-Arg-Pro.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.152-159
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• 2017

In marine environment, the durability of concrete and reinforcing steel is known to be deteriorate by the permeation of chloride ion into concrete. In this study the conductive photocatalyst was used to improve the seawater corrosion resistance of the concrete and steel. Mortar and concrete samples were prepared by mixing with various amounts of conductive active carbon and photocatalytic powder($TiO_2$). The compressive strength of concrete was decreased with the increase of the amount of conductive carbon powders. The samples containing conductive carbon and photocatalytic powders showed the superior seawater corrosion resistance compared with the ordinary sample, which was verified by XRF analysis showing the concentration of chloride ion($Cl^-$) of mortars and concretes. The inhibitive effect of photocatalyst against chloride attack was discussed with the diffusion coefficient of chloride ion into mortar and concrete.

• Clean Technology
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• v.17 no.1
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• pp.37-40
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• 2011

Some ionic liquids are suitable for catalysts and solvents which are applicable to $CO_2$ fixation reaction converting $CO_2$ to carbonate. Using the ionic liquids, the synthesis process will become greener and simpler because of easy catalyst recycling and unnecessary use of volatile and harmful organic solvents. In this work, the synthesis of propylene carbonate from propylene oxide using carbon dioxide and ionic liquids were measured at high pressures up to ~140 bar and at temperatures between $60^{\circ}C$ and $80^{\circ}C$. As a results, we found the optimum condition and obtained the maximum yield under that condition.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.77-77
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• 1999

박막시료의 분석에는 RBS, XPS, SIMS, AES 등이 주로 이용되고 있으며, 특히 RBS는 비교체가 필요없고 정량성이 좋다는 장점 때문에 중요하다. 그러나 RBS는 원리적으로 경원소에 대한 감도가 낮아 기판원소보다 무거운 질량을 갖는 원소의 분석에만 이용되는 것이 보통이다. 이러한 단점을 보완하기 위해 본 연구에서는 수년전부터 RBS와 비슷한 원리를 갖고 같은 장비를 이용하여 수행이 가능한 경원소 분석법인 TOF-ERDA(Time of Flight Elastic Recoil detection)을 개발하여 실용화 하였다. 본 연구실에서 보유하고 있는 미국 NEC사의 5SDH 가속기는 최대 가속전압이 1.7MV로 Cl5+ 이온을 사용하는 경우 10 MeV가 최대 가속에너지가 된다. 이런 정도의 에너지 범위에서는 TOF spectrometer의 시간분해능이 아주 높을 필요가 없고 비교적 작은 가속기로도 분석이 가능하며, 수소의 검출효율이 우수하다는 점 등 많은 장점이 있다. 그러나 한편으로는 분석가능한 깊이가 수천 $\AA$ 정도로 제한되고 질량 분해능도 수십 MeV 내지 100MeV 이상의 고에너지 이온빔을 이용하는 경우에 비해 떨어진다는 단점이 있다. 또한 묵운 원소의 분석이 불가능하기 때문에 경원소의 분석에 국한하여 적용하고 무거운 원소에 대해서는 RBS를 병용하게 된다. 본 연구에서는 일본 이화학연구소의 선형가속기인 RILAC으로부터 얻은 40MeV Ar 이온 및 138 MeV Xe 이온을 이용하여 TOF-ERDA 시스템을 제작하였다. 그러기 위해서 고에너지 이온의 비행시간을 측정하는 목적으로 높은 시간 분해능을 갖는 시간 검출기를 설계, 제작하였다. 또한 표적함 밑에는 회전원판이 있어 시간검출기 및 에너지 검출기가 중앙의 시료홀더를 중심으로 회전이 가능하도록 되었다. 회전은 표적함 밖에서 원격조정 가능하다. 이렇게 함으로써 검출각을 임의로 바꾸면서 측정이 가능하도록 하였다. 제작된 분석시스템의 성능을 확인하기 위해 YBaCuO 초전도 박막을 측정하였으며 그 결과를 그림에 나타낸다. 저 에너지 ERDA에서는 나타나기 힘든 Ba, Y, Cu 등의 무거운 원소의 피크들이 분명히 나타남을 확인할 수 있다.

• Journal of Life Science
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• v.18 no.8
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• pp.1164-1168
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• 2008

We investigated gravitropic responses in the primary root of maize (Zea mays) seedlings which were exposed to salt stress. The maize roots salt-stressed with higher than 100 mM NaCl or KCl started to reveal enhanced gravitropic curvature after 2 hours form the gravi-stimulation. Such a promotion was not caused by sodium phosphate, but invoked by potassium phosphate, indicating the active component is $K^{+}$. Because NaCl increased gravitropic curvature, despite that $Na^{+}$ did not played any role, we evaluated the role for $Cl^{-}$ by comparing the effects of $MgCl_2$ and $MgSO_4$. The enhancement of the curvature only with $MgCl_2$ revealed that $Cl^{-}$ played a role in the gravi-response, indicating the involvement of anion channels. These results suggest that both of $K^{+}$ and $Cl^{-}$ play roles in the regulation of osmosis that is required for cell expansion in gravitropism as well as in nyctinasty and stomatal opening.