• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.336-341
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• 1993

In metal-affinify aqueous two-phase systems, protein partitioning is affected by a variety of parameters such as pH, the number of surface-accessible histidines, and the amount and partition coefficient of metallated polythylene glyco(PEG) ligand. To enhance partitioning of proteins with surface-accessible histidines, we have synthesized and used a (Cu(II)-ininodiacetic acid)$_2$-PEG20,000($Cu(II)_2IDA_2$-PEG20,000) as well as Cu(II)IDA-PEG5,000 as an affinity ligand. The partition coefficient of $Cu(II)_2-IDA_2$-PEG20,000 in a PEG5,000/dextran two-phase system was 30.1, which corresponded to a 3.8-fold increase over that of Cu(II)IDA-PEG5,000. The partitioning experiments were performed on four proteins, horse cytochrome c, S. cerevisiae cytochrome c, horse myoglobin, and sheep myoglobin. Partitioning of proteins which convey surface-accessible histidines was enhanced dramatically by the addition of $Cu(II)_2IDA_2$-PEG20,000 ligand. These results demonstrate that enhanced partitioning of metal-binding proteins in an aqueous two -phase system can by achieved by using an appropriate metallated PEG ligand.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.172-175
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• 2001

The high temperature deformation behavior of two-phase gamma TiAl alloy has been investigated with the variation of temperature and ${\gamma}/{\alpha}_2$ volume fraction. For this purpose, a series of load relaxation tests and tensile tests have been conducted at temperature ranging from 800 to $1050^{\circ}C$. In the early stage of the deformation as in the load relaxation test experimental flow curves of the fine-grained TiAl alloy are well fitted with the combined curves of two processes (grain matrix deformation and dislocation climb) in the inelastic deformation theory. The evidence of grain boundary sliding has not been observed at this stage. However, when the amount of deformation is large (${\epsilon}{\approx}$ 0.8), flow curves significantly changes its shape indicating that grain boundary sliding also operates at this stage, which has been attributed to the occurrence of dynamic recrystallization during the deformation. With the increase in the volume fraction of ${\alpha}_2$-phase, the flow stress for grain matrix deformation increases since ${\alpha}_2$-Phase is considered as hard phase acting as barrier for dislocation movement. It is considered that cavity initiation is more probable to occur at ${\alpha}_2/{\gamma}$ interface rather than at ${\gamma}/{\gamma}$ interface.

• Journal of the Korean Chemical Society
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• v.40 no.5
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• pp.365-373
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• 1996

A series of new dimesogenic compounds, di-4-(p-substituted phenoxycarbonyl) phenoxyethyltetramethyldisiloxanes, were prepared and identified. Another compound having a $\beta$-naphthyl group in the place of a p-substituted phenyl ring was also synthesized. The results were as follows, 1) The compounds were synthesized with considerably high yields in the range of 85% to 95%. 2) All of the compounds are enantiotropic and form smectic phase in melt, the compound with $X=NO_2$ is $S_A$ while the remaining ones are SB. 3) Liguid crystalline phase transion of the compounds were influenced in corporations of the size and electron affinity of the substituent. 4) The heats of melting ΔHm, are particulary low, while the heats of isotropization, ΔHi, are comparable to other dimesogenic compounds. 5) The smectic group efficiency of the substituents in the compounds is in the order of $H

• Journal of the Korean Chemical Society
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• v.39 no.1
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• pp.66-70
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• 1995

The soil humic acid was subdivided into four subfractions by molecular weight (F1: >100.000 dalton; F2: >100.000 dalton; F3: >10.000 dalton; F4: >2.000 dalton) using MP-dual hollow fiber ultrafiltration system. The characterization using IR, 1H and 13C NMR spectroscopy, showed similar spectroscopic features of HA, demonstrating that the bulk properties of HA subfractions are very similar to one another. IR spectral data showed a decrease in polysaccharide contents and increase in carboxylate functionality as molecular weight become smaller.functions. The structure of (NO) can be described by two interactions (N${\cdot}{\cdot}{\cdot}$N, N${\cdot}{\cdot}{\cdot}$O). One is the ONNO structure with an (N${\cdot}{\cdot}{\cdot}$N) interaction. In this structure, acyclic cis-ONNO with $C_{2v}$-symmetry, acyclic trans-ONNO with $C_{2h}$, and cyclic ONNO with trapezoidal structure ($C_{2v}$) are optimized at the MP2 level. The other structure is the ONON structure with an (N${\cdot}{\cdot}{\cdot}$O) interaction. In the structure, acyclic cis-ONON with Cs$^{-symmetry}$ and cyclic ONON of the rectangular ($C_{2h}$), square $(D_{2h})$, rhombic $(D_{2h})$, and parallelogramic $(D_{2h})$ geometries are also optimized. It is found that acyclic cis-ONNO $(^1A_1$) is the most stable structure and cyclic ONNO ($^3A_1$) is the least stable. Acyclic trans-ONNO ($^3A_1$) with an (N${\cdot}{\cdot}{\cdot}$N) interaction, acyclic trans-ONON and bicyclic ONON $(C_{2v})$ with (N${\cdot}{\cdot}{\cdot}$O) interaction, and acyclic cis- and trans-NOON with an (O${\cdot}{\cdot}{\cdot}$O) interaction can not be optimized at the MP2 level. Particularly, acyclic trans-ONNO with $C_{2h}$-symmetry can not be optimized at the CCSD(T) level. Meanwhile, acyclic NNOO ($^1A_1$, $C_s)$ and trianglic NNOO ($^1A_1$,$C_{2v})$ formed by the (O${\cdot}{\cdot}{\cdot}$N) interaction between $O_2$and $N_2$are optimized at the MP2 level. The binding energies and the relative energy gaps among the isomers are found to be relatively small./sec. Spiral CT scans during the arterial phase were obtained 35 seconds after the injection of contrast medium. CT findings of 78 lesions less than 4cm in diameter were correlated with angiographic findings. Results : The attenuation of lesions was high(n = 69), iso(n = 5), and low(n = 4) compared with liver parenchyma during the arterial phase of spiral CT. In lesions with high-, iso-, and low-attenuation during the arterial phase of spiral CT, hypervascularity on angiograms was found in 63 of 69(91.3%), three of five(60%), and three of four lesions(75%), respectively. Six lesions with high-attenuation on the arterial phase of spiral CT were not seen on angiography. Two iso-attenuated and one low-attenuated lesion were hypovascular on angiograms. Conclusion : The results of this study suggest that with some exceptions there was good correlation between the arterial phase of spiral CT and angiography.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.96-98
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• 2005

Proposed Multi-level PDP sustain Driver make use of element which has a low voltage rating instead of suggested method by the existing Webber and it passes through a second phase both rising and falling at sustaining voltage waveform In accordance with the change of timing phase(Tr1, Ti1, Tr2) performance comparison of a electric discharge characteristics in a PDP module has been carried out. At the conclusion of experimentation, the feature is extended by alteration of Ti1 and it has little to do with alteration of Tr1.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.5
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• pp.12-23
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• 1994

The two-phase flow is observed in power plants, chemical process plants, and refrigeration systems etc., and it is very important to solve the heat transfer mechanism of a boiler, an automic reactor, a condenser and various types of evaporators. Recently, the problem of two phase heat transfer is braught up in many regions with development of energy saving technique. In flow boiling system it is necessary to store data in each condition because the heat transfer characteristics of flow boiling region vary by the change of flow pattern and the magnetude of heat flux to tube length, and be subtly affected by the flow and heating condition. So basic study for knowing flow pattern in heat transfer region and the relation between heat transfer characteristic and flow condition is desired to accumulate data in wide variety of liquid and flow system in the study of heat transfer of two phase flow. In this study R-113 was selected as working fluid whose properties were programmed by least square method, and experiment was conducted in the region of mass flow $1.628{\times}10^6$~$4.884{\times}10^6$/kg/$m^2$hr with inlet subcooling 10~3$0^{\circ}C$, sustaining test section inlet pressure to 1.5kg$_f$/$cm^2$abs.

• Solar Energy
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• v.15 no.3
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• pp.15-27
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• 1995

This study presents experimental and numerical results of the temperature characteristics, the heat transfer phenomema, and the heat storage quantity during the heat storage process with sodium phyrophosphate decahydrate($Na_4P_2O_7{\cdot}10H_2O$)-Phase Change Material(PCM) in a latent heat storage tank(cubic type). It was proved that heat transfer by conduction was dominant because PCM($Na_4P_2O_7{\cdot}10H_2O$) during heating processes was gel phase, not liquid phase The gap ratio(rate of air content) of PCM became smaller, the thermal capacity of PCM became larger, therefore the temperature distribution of PCM slowly increased than that of large gap ratio. There was maximum 15% difference between measured temperatures and calculated temperatures.

• Fibers and Polymers
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• v.7 no.1
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• pp.12-19
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• 2006

For thermal adaptable fabrics, the polyurethane-urea microcapsules containing phase-change materials (PCMs: hexadecane, octadecane and eicosane) were successfully synthesized by interfacial polycondensation using 2,4-toluene diisocyanate (TDI)/poly(ethylene glycol) (PEG400)/ethylene diamine (EDA) as shell monomers and nonionic surfactant NP-12 in an emulsion system under stirring rates of $3,000{\sim}13,000$ rpm. The mean particle size of microcapsule decreased significantly with increasing the stirring rate up to 11,000 rpm, and then leveled off. The mean particle size increased with increasing the content and molecular weight (eicosane > octadecane > hexadecane) of PCMs at the same stirring rate. The mean particle sizes of microcapsules were found to decrease with increasing the NP-12 content up to 1.5 wt%, and thereafter increased a little. It was found that the melting temperature ($T_m$) and crystallization temperature ($T_c$) of three kinds of encapsulated PCMs and their enthalpy changes (${\Delta}H_m,{\Delta}H_c$) increased with increasing PCM contents. The encapsulation efficiencies (Ee) of hexadecane microcapsule linearly increased with increasing the content of hexadecane. It was found that the stable microcapsule containing 50 wt% of hexadecane could be obtained in this study. However, Ee of octadecane and eicosane microcapsules increased with increasing PCM's contents up to 40 wt%, and then decreased a little. By considering the encapsulation efficiency, it was found that the maximum/optimum contents of octadecane and eicosane microcapsules were about 40 wt%. By the dynamic thermal performance test, it was found that the maximum buffering levels of Nylon fabrics coated with hexadecane, octadecane, and eicosane microcapsules were about $-2.4/+2.9^{\circ}C,\;-3.6/+3.6^{\circ}C\;and\;-4.0/+4.7^{\circ}C$, respectively.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.62-68
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• 2003

Ba-ferrite particles added with Co and Ti, which were known well the additives for the control in coercivity, were synthesized by sol-gel method. In the range 90 to 120 minute reaction time, a stable sol solution which showed no change with temperature, pH, viscosity and aging time. After dried and heat treatment of sol solution, Ba-ferrite phase formed at $700^{\circ}C$ with Differential Thermal Analysis(DTA) and X-Ray Diffractometer(XRD) measurement. The crystallinity became to be better with increasing the temperature. It were showed by Scanning Electron Microscopy(SEM) that Ba-ferrite increased to particle sizes as increasing heating temperature and obtained of narrow particles size distribution. Also, magnetic characteristics of Ba-ferrite powders Co and Ti added were observed by a Vibrating Sample Magnetometer(VSM). Saturation magnetization$(M_s)$ was not much changed, however. the coercivity$(H_c)$dramatically dropped with addition of Co and Ti.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.146-148
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• 2006

This paper deals with a simple structured power quality disturbance generator for nonlinear load devices. The proposed generator can be applied to the performance test of custom power devices. Voltage sag, swell, outage, unbalance and phase jump after outage are provided by the generator. The improving phase jump operating principle of the generator is described and analysed. The usefulness of the generator is verified through simulation.