• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.563-567
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• 1999

Reverse osmosis concentration for cephalosproin C was studied using a polyamide composite membrane, FT-30 in spiral wound type with high solute rejection. The experiments were carried out in the aqueous solution of cephalosporin C for water flux, solute rejection and mass transfer coefficient under applied pressure of $4{\sim}20kg/cm^2$, feed concentration of 100~1000 mg/L and feed velocity of 2.8 and 5.6 L/min at room temperature. The effect of operating pressure on the separation of cephalosporin C showed that permeate flux increased with increasing operation pressure. These results are consistent with those predicted by Kedem-Katchalsky model. Solute rejection was nearly 1. The increase of feed concentration caused the reduction of cephalosporin C rejection, which was higher at low concentration than at high concentration, but degree of reduction was small.

• Journal of Korea Foundry Society
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• v.12 no.3
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• pp.220-229
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• 1992

The degree of purification and the macrostructure of high purity aluminium were studied through the alternate stirring method in order to improve the nonuniformity of solute concentration in the unidirectional stirring method. The $2^3$ factorial design was done to examine the effects of experimental factors more qualitatively. In the relatively low stirring speed of 1500 rpm with alternate stirring mode, the uniform solute profile and refined grain structure were obtained due to strong washing effect and turbulent fluid flow. It was induced by the transition of the momentum boundary layer by alternation of the stirrer. It was concluded from this study that the alternate stirring mode was more effective to obtain the uniformity of solute even in the stirring speed of 1500 rpm. But the degree of purification decreased below the critical alternating period. When 2N(99.8wt.%) aluminium was used as the starting material the morphology of solid-liquid showed the cellular shape and the columnar grains were inclined to the direction of rotation. This inclined grain growth resulted from the difference of relative velocities of solid and liquid. The inclined angle was increased as the stirring speed increased and solidification proceeded. In the case of 4N aluminium, there was no inclined grain growth and it was confirmed from the macrostructure and SEM work that the morphology of solid-liquid interface was planar. From the factorial design, it was found that the alternate stirring mode showed poorer purification effect than that of unidirectional stirring mode at low speed(500 rpm). In addition, the factor that had the most significant effect on the degree of purification was the stirring speed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.1
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• pp.55-58
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• 1999

Plant water status during growth is directly and indirectly associated with seed yield. The objective of the present study was to determine the genotypic differences in leaf water characteristics at an early growth stage of soybean [Glycine max (L.) Merrill] plants through the pressure-bomb technique. Measurements of water potential as well as relative water content (RWC) were made at the third leaf from the fully-expanded top leaf of eight different soybean genotypes grown for 31 to 35 days after field emergence. On the basis of the modified exponential model, pressure-volume (PV) curves were fitted well ($R^2$=0.92＊＊ to 0.99＊＊ for the curvi-linear region and R=0.67＊＊ to 0.96＊＊ for the linear region), indicating that a segmented model using PROC NLIN of SAS could be used effectively to estimate the leaf water characteristics. The regression analysis for the pressure-volume (PV) curve revealed genotypic variation in the solute potential at saturation (Ψ$_{s,sat}$ :-10.7 to -14.8 bar), solute potential at incipient plasmolysis (Ψ$_{s,ip}$ : -14.3 to -18.3 bar), RWC at incipient plasmolysis (RW $C_{ip}$ : 83.3 to 91.7%), high integrated turgor pressure from saturation to plasmolysis ( $_1$$^{b}$ : 0.39 to 0.81), and maximum volumetric modulus of elasticity ($\varepsilon$$_{max}$ : 150 to 445 bar).).

• Journal of Sensor Science and Technology
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• v.9 no.5
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• pp.350-356
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• 2000

The optimum composition ratios of primary solute(p-terphenyl) and secondary solute(popop) have been investigated in order to fabricate plastic scintillator with higher light output and less radiation damage. The radiation damage induced by $^{60}Co$ $\gamma$-irradiation depends on mainly the concentration of secondary solute. The spectral range of the luminescence was $400{\sim}450\;nm$, its peak emission appeared at 415 nm. The transmittance and the light output were not changed by radiation damage up to $1{\times}10^4\;Gy$ irradiation with $^{60}Co$ $\gamma$-rays.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.68-74
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• 2014

In the spiral wound module of the pressure-retarded osmosis (PRO) system for the salinity gradient power generation, effects of the inlet pressure differences between feed-channel and draw-channel were studied. Fluxes of water and solute through membrane and power were estimated. The water flux through membrane decreased along the x-direction and increased along the y-direction with the increase of inlet pressure differences between two channels. On the other hand, the solute flux through membrane showed the opposite trend. The concentration of flow in the feed-channel increased a lot along the y-direction and that in the draw-channel decreased along the x-direction. In our system, for the inlet pressure differences of 1~11 atm, the flow rate in the feed-channel decreased about 8~13% and that in the draw-channel increased by the same amount. The power density increased and then decreased with the increasing inlet pressure difference.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.796-801
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• 1992

An empirical Lewis basicity, DN, for eight mixed methanol solvents has been measured by the solvatochromic behavior of the [Cu(tmen)(acac)]$CIO_4$. The change of DN in mixed methanol solvents is not correlated with composition of the mixtures and divided into three groups: (1) dipolar aprotic solvents contribute mainly to the solvation of solute (MeOH-DMSO, MeOH-PY, MeOH-DMF), (2) two components of mixture contribute equally to the solvation of solute (MeOH-MeCN, MeOH-dioxane, MeOH-AC) and (3) methanol contributes entirely to the solvation of solute (MeOH-DCE, MeOH-TCE). The relationship between DN and Kamlet-Taft's $B_{KT}$ for mixed methanol solvents was found to agree well. These DN values also were a useful factor to analysis of reactivity for mixed methanol solvents.

• Journal of Korea Water Resources Association
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• v.31 no.3
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• pp.347-360
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• 1998

Numerical simulations for fluid flow and solute transport in a fracture rock masses are performed by using a transient flow model, which is based on the three-dimensional stochastic and discrete fracture network model (DFN model) and is coupled hydraulic model with mechanical model. In the numerical simulations of the solute transport, we used to the particle following algorithm which is similar to an advective biased random walk. The purpose of this study is to predict the response of the tracer test between two deep bore holes (GPK1 and GPK2) implanted at Soultz sous Foret in France, in the context of the geothermal researches.l The data sets used are obtained from in situcirculating experiments during 1995. As the result of the transport simulation, the mean transit time for the non reactive particles is about 5 days between two bore holes.

• Journal of Korean Neurosurgical Society
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• v.38 no.6
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• pp.431-434
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• 2005

Objective : Subarachnoid hemorrhage[SAH] is commonly associated with polyuria [solute diuresis or water diuresis]. The authors investigate the incidence and clinical characteristics of polyuria with special reference to the administration of osmotic diuretics. Methods : One hundred and forty eight patients with high urine output [>200ml/hr] after ruptured cerebral aneurysm operated early from Jan 1998 to Jun 2003 were selected. Water diuresis [diabetes insipidus, DI] was differentiated from solute diuresis by lower urine specific gravity [<1.005] and higher plasma osmolality. The incidence and mode of onset of polyuria were compared between two types of diuresis. Additionally, the relationships between development of polyuria and clinical features including aneurysm location, clinical grade, Fisher grade, and outcome were analyzed. Osmotic diuretics were not routinely used in patients with Hunt-Hess grade I-III since July 2001. Results : Annual incidence of polyuria decreased markedly since July 2001 : 45.2% in 1998, 34.5% in 2001, 11.9% in 2003. Postoperative DI occurred in $2.4{\sim}11.1%$. DI developed mainly from ruptured anterior communicating artery aneurysm. The mean interval between the last SAH and the onset of DI was 7.1 days [range $1{\sim}27$ days] and lasted mean 4.6 days. When compared with solute diuresis, the development of DI was significantly delayed. Other clinical features were not closely related to polyuria. Conclusion : Uncontrolled polyuria may lead to cerebral ischemia and electrolyte imbalance because SAH patients are already predisposed to hypovolemia, and will risk precipitating the opposite situation with overhydration. We can decrease the development of polyuria without routine use of osmotic diuretics, by avoiding the increased intracranial pressure such as the intraoperative ventriculostomy and gentle brain retraction in good grade patients.

• Journal of The Korean Association For Science Education
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• v.26 no.7
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• pp.805-812
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• 2006

In this study the description patterns of chemistry textbooks on the boiling point elevation phenomenon and the understanding patterns of high school students, pre-service teachers and chemistry teachers were investigated. High school chemistry II textbooks developed in the 6th and 7th national curricula were analyzed and the conception patterns of subjects on this phenomenon were categorized using a questionnaire developed for this study. The description patterns of science textbooks were classified into three: 'decreasing of surface solvent molecules', 'attraction force between solvent and solute molecules' and 'decreasing of surface solvent molecules and attraction force between solvent and solute molecules'. In the result of the conception analysis, the ratio of 'attraction force between solvent and solute molecules' was high among students, pre-service teachers, and chemistry teachers. There was a propensity that they would like to explain the boiling point elevation in terms of enthalpy rather than entropy, and in order to analyze this propensity, follow-up interviews were carried out.

• Journal of the Korean Chemical Society
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• v.48 no.4
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• pp.399-413
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• 2004

In this study, a survey was conducted of students of elementary through college on their conceptions of phenomenon related with dissolution, saturation, and extraction. The teaching strategies of elementary and secondary teachers related to dissolution phenomena were also investigated. Most of elementary and secondary school students thought of dissolution as a phenomenon in which particles broke into the spaces between other particles. This explanation called 'space conception' can be sought in elementary school science textbooks. Some of high school students also had this type of thought. A concept of dissolution phenomenon as 'hydration through attraction of solvent and solute' was held by most of students of 11th, 12th grade, and college. This explanation called 'attraction concept' can be sought in high school chemistry textbooks for 11th and 12th grade. But many students of elementary through college used analogies and models related to 'space conception' when they tried to explain the dissolution phenomena. This indicates that the 'attraction concept' was not firmly established in the students' cognition. 90% of elementary school teachers thought and taught dissolution as a phenomenon in which two different size particles were mixing together like as mixing beans and millets. The model does not represent the attractions among solvent-solvent particles, solvent-solute particles, and solute-solute particles. This model only represents the space size effect (smaller size particles fitting into the spaces of larger size particles). Half of the secondary school teachers also had 'space conception' and only 20% of the teachers had 'attraction concept' Many teachers who had 'attraction concept' used to represent explanation related to 'space conception' for teaching dissolution.