• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1026-1030
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• 1999

The properties of semiflexible polymer brushes are studied by applying the classical limit of mean-field approach for chains with marginal chain stiffness. Using the mean-spherical Gaussian model, the most probable configuration for semiflexible chains is obtained, which reduces to the parabolic brush of Milner et al. [Mac-romolecules 1988, 21, 2610] in the flexible limit. From this configuration, equilibrium brush height as well as interactions between semiflexible brushes are estimated.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.401-405
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• 2010

스크램제트 엔진에 대한 주요 성능설계기법에 대한 연구를 통해 효율적인 해석모델을 제시하였다. 초음속 흡입구의 설계에 있어 최대 전압력회복률을 얻기 위한 Oswatisch의 설계기준을 적용하여 흡입구의 압축각도를 설계하였다. 초음속 연소기의 해석을 위해 준 1차원 해석모델을 제시하였으며, 이에 화학평형 모델 및 유한화학반응 모델의 두 연소모델을 적용함으로서 그 결과를 비교분석하였다. 또한 Starkey의 Waverider에 대한 1차원 해석결과와 비교를 통해 연소모델의 결과를 검증하였다. 가상의 설계조건에 대한 엔진의 성능해석을 수행함으로서 모델의 적용가능성을 확인하였다.

• Journal of Welding and Joining
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• 제16권5호
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• pp.56-66
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• 1998

During solidification or welding of alloys, the solute redistribution brings out microsegregation. The microsegregation causes the formation of non-equilibrium second phases, shrinkage and porosity degrading mechanical/chemical properties Therefore, it has been required to predict microsegregation quantitatively. To predict the degree of microsegregation, more exact and appropriate computer simulation technique has been actively used during last two decades. To predict the degree of microsegregation in weld metal, an advanced two dimensional model was suggested. In the new model, both primary and secondary arm regions were defined for the analysis region. The growth in the primary arm regina was assumed to be a planar for effective calculation. Especially, for the growth of a secondary arm, a simple and effective mathematical function was established to show the growing pattern, the solute diffusion in the solid phase was calculated by finite difference method (FDM). The solid-liquid interface movement was considered to be in local equilibrium state. The experiments for welding of 310S stainless steel were carried out in order to examined the reasonability and feasibility of this model. The concentration profiles of the solute predicted by this model were compared with those obtained from experimental works.

• 에너지공학
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• 제2권2호
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• pp.225-230
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• 1993

n-dodecane-1-decanol, n-dodecane-1-dodecanol 및 1-decanol-1-dodecanol계 의 14$0^{\circ}C$ 등온 기액평형 데이타를 static method로써 Head Space Gas Chromatography (H.S.G.C)를 이용하여 측정하였다. 액상의 비이상성을 고려하여 계산된 활동도계수는 Margules, Van Laar, Wilson, NRTL g$^{E}$ 모델을 이용하여 상관관계를 구하였으며, Redlich-Kister의 열역학적 일치성 시험을 통해 데이타의 신빙성을 확인하였다. 측정한 이성분계중 n-dodecane-1-decanol계는 최소 공비점을 가짐을 알 수 있었다.

• 한국환경과학회지
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• 제21권7호
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• pp.805-813
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• 2012

The removal property of Cu and Zn ions by chemical precipitation and adsorption using zeolite(Z-C1) prepared from coal fly ash(CFA) were evaluated in this study. Adsorption kinetic and equilibrium mechanisms described to analyze parameters and correlation factors with Lagergen $1^{st}$ and $2^{nd}$ order model and Langmuir and Freundlich model. Analysis of adsorption kinetics data revealed that the pseudo $2^{nd}$ order kinetics mechanism was predominant. The equilibrium data in pH 3 - 5 were able to be fitted well to a Langmuir model, by which the maximum adsorption capacities($q_{max}$) were determined at 124.9 - 140.1 mg $Cu^{2+}/g$ and 153.2 - 166.9 mg $Zn^{2+}/g$, respectively. We found that Z-C1 has a potential application as absorbents in metal ion recovery with low pH.

• Advances in environmental research
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• 제3권2호
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• pp.131-149
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• 2014

Two different model selection indices, the Akaike information criterion (AIC) and the coefficient of determination ($R^2$), are used to discriminate competing isotherm equations for aqueous pollutant removal systems. The former takes into account model accuracy and complexity while the latter considers model accuracy only. The five types of isotherm shape in the Brunauer-Deming-Deming-Teller (BDDT) classification are considered. Sorption equilibrium data taken from the literature were correlated using isotherm equations with fitting parameters ranging from two to five. For the isotherm shapes of types I (favorable) and III (unfavorable), the AIC favors two-parameter equations which can easily track these simple isotherm shapes with high accuracy. The $R^2$ indicator by contrast recommends isotherm equations with more than two parameters which can provide marginally better fits than two-parameter equations. To correlate the more intricate shapes of types II (multilayer), IV (two-plateau) and V (S-shaped) isotherms, both indices favor isotherm equations with more than two parameters.

• Environmental Engineering Research
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• 제11권1호
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• pp.33-44
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• 2006

The objective of this study was to develop and assess a method for estimating the rain scavenging ratios (RSRs) of particle-bound PAHs and PCBs using measured scavenging ratio of particulate matters (PM) and routinely available data of physico-chemical properties of PM. Paired atmospheric and rainwater sampling was conducted for a total of 4 rain events. Assuming equilibrium partitioning in rainwater-gas-PM system, an equation was derived for estimating the RSR of particle-bound chemicals as a function of RSR of PM and three equilibrium partition constants (i.e. dimensionless Henry's law constant, gas-particle partition coefficient, and water-particle partition coefficient). For all PAHs, the model significantly under-predicted the RSR while the model prediction for PCBs agreed with observation mostly within a factor of 5. The RSR model for the chemicals is of limited use as its accuracy critically depends on how close the observed partitioning of the chemicals in the gas-PM-rainwater system is to that estimated under the equilibrium assumption.

• 한국지반공학회지:지반
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• 제11권2호
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• pp.121-138
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• 1995

여러종류의 화합물질들이 동시에 토양에 유출되었을 때 이들이 토양에 흡착하는 정도를 예측 함에는 Langmuir Competitive Model과 IAS(Ideal Adsorption Model) 등이 널리 사용되고 있 는데, 5개의 유기화합물질(Phenol, 2,4-Dichlorophenol, 2,4,6-Trichlorophenot Brucine, Thiourea)과 2종류의 토양을 이용한 흡착실험을 통해서 이 Model들의 예측도를 비교분석하였다. 흡착실험은 이 화합물질들이 독자적인 상태에서 그리고 혼합상태에서 각각 구분하여 실헙하였다. 일반적으로 IAS Model이 Langmuir Model보다 혼합상태에서 각 구성 화합물질들의 흡착을 더 정확히 예측하였다. Langmuir Model은 Phenol과 함께 섞여있는 다른물질의 농도가 높을 때 Phenol의 흡착을 낮게 예측하였다. 두가지 Model모두 Thiourea가 혼합상태에 있을때 흡착정도를 만족스럽게 예측하지 못했는데 Thiourea는 Aliphatic화합물이고 나머지 4개는 Aromatic화합물이다.

• Korean Chemical Engineering Research
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• 제48권5호
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• pp.632-637
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• 2010

1기압 298.15 K에서 water + tetrahydrofuran + butyl acetate + isoamyl alcohol를 포함한 4성분 액-액추출계의 상평형에 대하여 연구하였다. Butyl acetate + isoamyl alcohol을 혼합용매로 사용하였으며, 수용액으로부터 tetrahydrofuran를 추출함에 있어서 혼합용매 사용의 효과를 고찰하기 위하여 각 4성분계에 대한 용해도 곡선, 대응선(Tie-line), 분배도, 선택도를 측정하였다. 또한 실험에 의한 대응선(Tie-line) 데이터를 UNIFAC 모델식으로부터 예측된 값들과 비교한 결과, 액-액평형에 대한 UNIFAC 모델이 본 실험에 설정된 4성분계에 대하여 혼합용매 비율 75/25, 50/50, 25/75에 따라 3.35, 5.21, 5.65%의 편차가 나타남을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3391-3398
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• 2013

The carboxylated multiwall carbon nanotubes (MWCNT-COOH) and functionalized with isatin derivative (MWCNT-isatin) have been used as efficient adsorbents for the removal of lead (Pb) from aqueous solutions. The influence of variables including pH, concentration of the lead, amount of adsorbents and contact time was investigated by the batch method. The adsorption of the lead ions from aqueous solution by modified MWCNTs was studied kinetically using different kinetic models. The kinetic data were fitted with pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The sorption process with MWCNT-COOH and MWCNT-isatin was well described by pseudo-second-order and pseudo-first-order kinetics, respectively which it was agreed well with the experimental data. Also, it involved the particle-diffusion mechanism. The values of regression coefficient of various adsorption isotherm models like Langmuir, Freundlich and Tempkin to obtain the characteristic parameters of each model have been carried out. The Langmuir isotherm was found to best represent the measured sorption data for both adsorbent.