• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3293-3297
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• 2012

The solvolysis rate constants of 5-nitro-2-furoyl chloride (5-$NO_2(C_4H_2O)$-2-COCl, 1) in 27 different solvents are well correlated with the extended Grunwald-Winstein equation, using the $N_T$ solvent nucleophilicity scale and YCl solvent ionizing scale, with sensitivity values of $1.20{\pm}0.05$ and $0.37{\pm}0.02$ for l and m, respectively. The activation enthalpies (${\Delta}H^{\neq}$) were 5.63 to $13.0kcal{\cdot}mol^{-1}$ and the activation entropies (${\Delta}S^{\neq}$) were -25.9 to $-43.4cal{\cdot}mol^{-1}{\cdot}K^{-1}$, which is consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effect (SKIE, $k_{MeOH}/k_{MeOD}$) of 2.65 was also in accord with the $S_N2$ mechanism and was possibly assisted using a general-base catalysis. The product selectivity (S) for solvolysis of 1 in alcohol/water mixtures was 1.2 to 11, which is also consistent with the proposed bimolecular reaction mechanism.

• Korean Journal of Materials Research
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• v.15 no.12
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• pp.786-790
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• 2005

We investigated the particularity of temperature and composition changes in $xNa_2O{\cdot}(52.5-x)B_2O_3{\cdot}47.5SiO_2$ glasses by use of FT-IR, $^{11}B$ NMR, Raman spectrometer. From FT-IR and $^{11}B$ NMR spectrometer, we thought that tetrahedral boron, $BO_4$ units are created $N_4$ increasing tendency generated near $600^{\circ}C$. It's expected that composition ana heat treatment directly contributed to structural changes, this changes are following to $Na_2O$ increasing or decreasing. caused by $N_4\;and\;BO_4$ units are caused by relatively increasing or decreasing in the glasses' structure. Particularly, $BO_4$ units are converted to $BO_3$ units after $600^{\circ}C$ heat treatment for 50h in the composition of $x<18(R<0.5,\;R=Na_2O/B_2O_3\;mol\%)$. On the order hand, $BO_3$ units are converted to, $BO_4$ units after $600^{\circ}C$ heat treatment for 50h in the composition of $x{\geq}18\;(R>0.5)$. This particularity of composition and temperature dependence of structural changes are similarly represented by Raman analysis results.

• FLOWER RESEARCH JOURNAL
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• v.19 no.2
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• pp.110-114
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• 2011

This experiment was conducted to examine the ideal condition for multiple colors dyeing of cut rose, 'Akito'. Four different colors of dye were applied to make multiple flower colors in cut rose by absorption method. Acidic condition around pH 3.5 showed the fastest absorption speed in all four colors. There is no difference at each pH levels, at part of leaves dyeing, it is more affected colors rather than pH levels in purple and blue colors. From vary concentration of each dyes, $10g{\cdot}L^{-1}$ concentration of dyeing solution gave the best color definition. But it's not significant and result was different by each color in a same concentration. 10 minutes of dyeing performed pastel color and 30 minutes performed the best color definition, but the 30 minutes treatment accompanied with significant dyeing on the leaves also. As a result of this experiment, optimum condition for dyeing cut rose, 'Akito' requires pH 3.5, $5-10g{\cdot}L^{-1}$ of dye concentration and 10-30 minutes treatment.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.535-542
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• 2005

Two series of experiments on the performance of beam-column joints in High-Strength Reinforced concrete frames were carried out. Main experimental parameters were : concrete strength, column axial load and amount of joint hoop reinforcement. Test result showed that the ultimate shear strength of exterior joints increased of column axial compressive force and the amount of the joint hoop reinforcements. Through the regression analysis on the 24data, the following equation is obtained $jv_u=(2.935{\times}10-3\;{\rho}jw{\cdot}fy\;+\;0.365){\sqrt{f_{ck}}}$

• Horticultural Science & Technology
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• v.32 no.6
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• pp.753-761
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• 2014

Growth and flowering of Cymbidium 'Red Fire' and 'Yokihi' plants were examined in a greenhouse with cooling systems in summer, and with night interruption (NI) lighting in winter as a forcing culture system. The greenhouse was divided into two sections with separate cooling controls during the summer season. One section was cooled by a mist system (mist), while the other section was cooled by a shade screen (shade). During the winter, the greenhouse was redivided into three sections within each cooling system. Plants were grown with NI either at a low light intensity of $3-7{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$(LNI) or a high l ight intensity of $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$(HNI) u sing h igh-pressure sodium l amps during the 22:00-02:00 HR. The control plants were grown under 9 h short-day condition. NI for 16 weeks and cooling for 9 weeks were employed twice during the 2 years of the experimental period. The air temperature was approximately $2^{\circ}C$ lower in the mist than in the shade and the relative humidity was 80 ${\pm}5%$ in the mist compared to $55{\pm}5%$ in the shade. The daily light integral in the mist section was 48% higher than in the shade section. The time from initial planting to flowering pseudobulb emergence decreased with both LNI and HNI for both cultivars, regardless of the cooling treatments. Under NI conditions, however, between 60% and 1 00% of plants of both cultivars flowered in the mist, whereas no or 20% of 'Red Fire' or 'Yokihi' plants, respectively, flowered in the shade treatment over 2 years. Plants grown under the mist had bigger pseudobulbs than those grown in the shade under both NI treatments. These results show that commercial use of NI in winter and a mist cooling system in summer would decrease crop production time to 2 years and increase profits in Cymbidium forcing culture.

• Journal of Adhesion and Interface
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• v.12 no.4
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• pp.133-137
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• 2011

Exfoliated graphite oxide (EGO) was prepared by graphite oxide in an aqueous solution of TMAOH. The hybrid graphene/Zn-Al LDH material was fabricated by the hydrothermal reduction of the solution of EGO, $Zn(NO_3)_2{\cdot}6H_2O$, $Al(NO_3)_3{\cdot}9H_2O$, urea, and trisodium citrate. That is, metal ions were absorbed on the surface of EGO, and Zn-Al LDH material was randomly dispersed on the surface of graphene along with a reduction process of EGO to graphene by hydrothermal treatment. The composition, morphology, and thermal property of the obtained graphene-based hybrid material were studied by FE-SEM, EDX, TEM, FT-IR, XRD, TGA, and DSC.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1747-1751
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• 2006

The dinuclear tetraazadiphenol macrocyclic nickel(II) complexes [$Ni_2$([20]-DCHDC)]$Cl_2$ (I), [$Ni_2$([20]-DCHDC)]$(ClO_4)_2{\cdot}2CH_3CN $ (II(b)) and [$Ni_2$([20]-DCHDC)$(NCS)_2$] (III) {$H_2$[20]-DCHDC = 14,29-dimethyl-3,10,18,25-tetraazapentacyclo-[25,3,1,$0^{4,9}$,$1^{12,16}$,$0^{19,24}$]ditriacontane-2,10,12,14,16(32),17,27(31), 28,30-decane-31,32-diol} have been synthesized by self-assembly and characterized by elemental analyses, conductances, FT-IR and FAB-MS spectra, and single crystal X-ray diffraction. The crystal structure of II(b) is determined. It crystallizes in the monoclinic space group P2(1)/c. The coordination geometries around Ni(II) ions in I and II(b) are identical and square planes. In complex III each Ni(II) ion is coordinated to $N_2O_2$ plane from the macrocycle and N atoms of NCS- ions occupying the axial positions, forming a square pyramidal geometry. The nonbonded Ni…Ni intermetallic separation in the complex II(b) is 2.8078(10) $\AA$. The FAB mass spectra of I, II and III display major fragments at m/z 635.1, 699.4 and 662.4 corresponding to [$Ni_2$([20]-DCHDC)(Cl + 2H)]$^+$, [$Ni_2$([20]-DCHDC)$(ClO_4\;+\;2H)]^+$ and [$Ni_2$([20]-DCHDC)(NCS) + 6H]$^+$, respectively.

• Journal of Korean Society of Forest Science
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• v.71 no.1
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• pp.66-73
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• 1985

Factors affecting isolation and fusion of protoplasts of three Quercus species were investigated and procedures for isolation, purification and fusion of protoplasts of the three species were also established. Unhardened leaves and rapidly growing callus cultures were good source of viable protoplasts. The optimum composition of enzyme mixture for rapid isolation of protoplasts from leaf mesophyll tissues and calli was Cellulase Onozuka R-10 (20g/l, Macerozyme R-10(10g/l), Pectinase(250 units/l, $CaCl_2$, $2H_2O$(14mM), $MgSO_4{\cdot}7H_2O$(1.8mM), $KNO_3$(1.0mM), $H_3BO_3$(1.0mM), $KH_2PO_4$(0.2mM), KI($1.0{\mu}M$), 1,4-dithiothreitol (0.1mM) and mannitol (0.6M). Optimum density of protoplasts for maximum fusion was $2{\times}10^5/ml$ which was the highest protoplast density given in this study. Optimum concentration and duration of PEG 1450 treatment for inducing fusion appeared to be 29%(W/V) final PEG 1450 concentration and 5-10 minutes, respectively.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1415-1417
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• 2003

Yoneyama 등이 2001년 기존의 potentiometry 형의 요소 센서보다 우수한 성능을 갖는ampeometry 정의 요소 센서를 제안한 이후, 전자 전달 메커니즘에 관한 관심이 집중되어 왔으나, urease로부터 전극 기질까지의 전자 전달 매질로서 전도성 고분자보다 쉽고 단순한 공정은 아직까지 제시된 바 없다. 본 논문에서는 전도성 고분자로서 polypyrrole(PPy)과 poly(3-methylthiophene)(P3MT)을 이용하여 다공성 실리콘(PS) 요소 센서를 제작하고 각각의 특성을 전기화학적으로 분석하였다. Urease 고정화 전압, 고정화 시간, 고정화 시의 효소 농도, 수소이온 농도 등이 감도에 미치는 영향은 PPy 와 P3MT 각각의 경우 유사한 경향성을 보였다. 감도 특성의 경우, PPy는 다공질 실리콘 전극과 평면 전극 각각에 대하여 1.55 ${\mu}A/mM{\cdot}cm^2$와 0.91 ${\mu}A/mM{\cdot}cm^2$였고, P3MT의 경우는 각각 8.44 ${\mu}A/mM{\cdot}cm^2$와 4.28 ${\mu}A/mM{\cdot}cm^2$의 감도를 보였다. 즉, PPy가 P3MT 보다 일반적으로 높은 감도를 보였고, 다공질 실리콘 전극을 사용하는 경우, 그렇지 않은 경우보다 약 2배외 감도 향상 효과를 기대할 수 있었다. 재현성이나 안정성의 경우는 P3MT 가 PPy 보다 우수하였다. 사용 빈도에 따른 감도 저하는 다공질 실리콘 전극의 경우 직선적으로 감소하셨으나 평면 전극의 경우는 지수함수적으로 감소하였다 시간에 따른 감도 저하 현상은 만15일 이후의 감도를 기준으로 하여, 10% 미만의 감도저하를 보임으로써 PPy, P3MT 모두 우수한 특성을 보였다.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.113-123
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• 2017

This study investigated effects of physical and chemical cleaning methods on the initial flux recovery of fouled membrane in membrane distillation process. A laboratory scale direct contact membrane distillation (DCMD) experiment was performed to treat digested livestock wastewater with 3.89 mg/L suspended solids, 874.7 mg/L COD, 543.7 mg/L nitrogen, 15.6 mg/L total phosphorus, and pH of 8.6. A hydrophobic PVDF membrane with an average pore size of $0.22{\mu}m$ and a porosity of 75 % was installed inside a direct contact type membrane distillation module. The temperature difference between feed and permeate side was maintained at $40^{\circ}C$ with the feed and permeate stream velocity of 0.18 m/s. The results showed that the permeate flux decreased from $22.1L{\cdot}m^{-2}{\cdot}hr^{-1}$ to $19.0L{\cdot}m^{-2}{\cdot}hr^{-1}$ after 75 hours of distillation. The fouled membrane was cleaned first by physical flushing and consecutively by chemicals with NaOCl and citric acid. After the physical cleaning the flux was recovered to 92 % as compared with the initial clean water flux of the virgin membrane. Then 94 % of the flux was recovered after cleaning by 2,000 ppm NaOCl for 90 minutes and finally 97 % of flux recovered after 3 % citric acid for 90 minutes. SEM-EDS and FT-IR analysis results presented that the foulants on the membrane surface were removed effectively after each cleaning step. The contact angle measurement showed that the hydrophobicity of the membrane surface was also restored gradually after each cleaning step to reach nearly the same hydrophobicity level as the virgin membrane.