• 한국가구학회지
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• 제19권1호
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• pp.83-90
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• 2008

Gypsum-wood composites were made by introducing inorganic substances into wood using calcium chloride, first treating solution, and sodium sulfate, secondary treating solution, by double diffusion process under atmospheric pressure at room temperature. The process conducted as follows: water saturated specimens were soaked in calcium chloride solutions at several concentration. Then the specimens were soaked further in saturated sodium sulfate solution, and they were leached in flowing tap water for 24h. To attain sufficient weight percent gain (WPG) values, the suitable concentration of calcium chloride and soaking time in saturated sodium sulfate solution were 20% and 48h, respectively. Inorganic substances were produced mainly in the lumina of tracheides. It was made sure that these substances were dihydrate gypsum($CaSO_4$ $2H_2O$) by X -ray microanalysis (SEM-EDX). The composites had good fire resistance due to low heat transfer rate of gypsum formed in wood. However, the composites had little decay resistances, because they showed high weight losses by test fungi attacks.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권2호
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• pp.34-39
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• 2010

In this study, the remediation of diesel contaminated soil was attempted with ozone treatment and Fenton reaction. About 10% of initial diesel concentration was removed by the ozone saturated solution. The pseudo-first order decomposition constant of diesel contaminated soil in the presence of 5% of hydrogen peroxide with 1.82, 2.82, 4.82, 6.82, and 11.82% of iron contents was 0.0228, 0.0308, 0.0482, 0.0471, and 0.0592 $min^{-1}$ respectively. The decomposition constant of the diesel was 0.0064 $min^{-1}$ with the addition of ozone saturated solution only. On the addition of ozone saturated solution in the presence of 5% hydrogen peroxide and 5% iron, the decomposition constant of the diesel was 0.0850 $min^{-1}$. These results indicated that the decomposition rate was 190% faster than without the addition of ozone saturated solution. Thus, the application of both ozone and the fenton reaction is promising for the remediation of the diesel contaminated soil.

• 한국전산구조공학회논문집
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• 제20권2호
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• pp.95-103
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• 2007

본 논문에서는 포화된 다공성매체에서 파동의 전파속도와 감쇠를 구할 수 있는 해석적 이론해를 유도하여 제시하였다. 이론해의 유도를 위하여 압축성의 고체입자와 간극수를 고려하는 완전 연계 Field모델을 사용하였다. 완전 포화된 다공성 매체의 해석을 위한 공학적인 접근방법이 채택되었으며, 균질 영역에서 1차원 파동의 전파를 위한 이론해가 유도되었다. 본 논문에서 유도한 이론해는 고체입자의 압축성, 간극수의 압축성, 다공성입자의 변형, 공간의 감쇠(Spatial damping) 등을 고려할 수 있어 매우 다양하게 사용될 수 있다. 또한 다양한 지반체에서 두 가지 종류의 파속(Wavespeed)과 감쇠계수를 계산하는데 이용 가능하다. 본 논문에서 제시한 이론해를 전산코드화하여 파동의 전파속도와 감쇠에 대한 파라미터연구를 수행한 결과는 본 연구의 II부에 제시할 예정이다.

• 농업과학연구
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• 제41권4호
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• pp.399-404
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• 2014

Soil moisture is an important factor for the availability and circulation of nutrients in arable soil. The purpose of this study was to set thresholds moisture content on soil nitrate concentration in the solution for real-time diagnosis. Sandy loam, silt loam, and sandy loam was filled with $1.2g\;cm^{-3}$ at Wagner pots, 0, 100, and $200mg\;L^{-1}$ of $KNO_3$ was saturated. Nitrate in standard solution was recovered about 95% by passing the porous cup. Nitrate concentrations in sampling of soil solution were examined by using a porous cup. The soil solution was higher in accordance with sandy loam> silt loam> clay loam, limited water filled pore space for sampling soil solution was 33.7, 56.4, and 62.2%, respectively. Nitrate concentration in the soil solution was negligible at sandy loam and silt loam during sampling periods, which was decreased about 50~82% in clay loam compared to the initial $NO_3$-N concentration in the saturated $KNO_3$ solution. Over limitation of soil solution sampling, soil EC and $NO_3$-N content were increased with the saturated $NO_3$-N concentration, regardless of soil texture (p<0.05). Conclusively, soil solution by using a porous cup was possible, regardless of the soil texture, which was useful for the diagnosis in nitrate concentration of soil solution. However, because nitrate concentration of soil solution in a clay loam changes, it was necessary for careful attention in order to take advantage for the real-time diagnosis of nitrogen management in soil.

• Computers and Concrete
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• 제15권1호
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• pp.127-140
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• 2015

The process of chloride ingress in saturated concrete was presented by a previous study that used a mathematical model for the same as that concrete. This model is to be studied chloride ion diffusion which is considered as a chemical phenomenon and is to be represented the chloride diffusion process to be a nonlinear partial differential equation (PDE). In this paper, this nonlinear PDE is solved by the Kirchhoff transformation to render into a linear PDE. This linear PDE associated with initial and boundary conditions is also solved by the Laplace transformation to obtain an analytical solution. To verify the serviceability and reliability of this proposed method, the practical application should be supplied. The input parameters were cited from the previous study. The free chloride concentration profiles obtained by the analytical solution of mathematical model for saturated concretes after 24 and 120 hrs of exposure were compared with the previous study. The predicted results obtained from proposed method have a tendency with experimental results obtained by the previous study and trend toward numerical results approximated by finite difference technique.

• 토지주택연구
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• 제1권1호
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• pp.59-65
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• 2010

The paper presents a comparison between a semi-implicit time integration linear finite element implementation and fully-implicit nonlinear Newton-Raphson finite element implementation of a triphasic small strain mixture formulation of an elastic partially saturated porous medium. The pore air phase pressure pa is assumed atmospheric, i.e., $p_a$ = 0, although the formulation and implementation are general to handle increase in pore air pressure as a result of loading, if needed. The solid skeleton phase is assumed linear isotropic elastic and partially saturated 'consolidation' in the presence of surface infiltration and traction is simulated. The verification of the implementation against an analytical solution for partially saturated pore water flow (no deformation) and comparison between the two implementations is presented and the important of the porosity-dependent nature of the partially saturated permeability is assessed on comparison with a commercial code for the partially saturated flow with deformation. As a result, the response of partially saturated permeability subjected to the porosity influences on the saturation of a soil, and the different behaviors of the partially saturated soil between staggered and monolithic coupled programs is worth of attention because the negative pore water pressure in the partially saturated soil depends on the difference.

• 한국세라믹학회지
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• 제27권5호
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• pp.577-582
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• 1990

The synthesis conditions of fibrous calcium sulfate hemihydrate were investigated by using phosphogypsum and calcium sulfate hemihydrate. The unstable organogel was deposited by adding methanol to the saturated solution with gypsum at ageing temperature, and it was crystallized to fibrous gypsum hemihydrate while methanol was removed by rapid filtrating. In case of using calcium sulfate hemihydrate, fibrous $\beta$-calcium sulfate hemihydrate was formed by adding methanol of 67% to saturated solution at 6$0^{\circ}C$ and ageing for 5 minutes and filtering with suction. Minor components in phosphogypsum did not affect the reaction.

• Bulletin of the Korean Chemical Society
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• 제17권9호
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• pp.798-802
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• 1996

The photochemical decomposition of aqueous ammonia in the absence (saturated with argon) and the presence of O2 (saturated with air or oxygen) has been investigated using 184.9 nm UV light. The decomposition of ammonia depended on the concentration of oxygen in the solution. With increasing the concentration of oxygen, the decomposition of ammonia diminishes. Hydrazine is found the major product from the irradiation. In the presence of oxygen, hydrogenperoxide was also produced. The product yields depended also on the concentration of oxygen in the solution. The initial quantum yield of the products and of the ammonia decomposed were determined. Probable reaction mechanisms for the reaction were presented from the products analysis.

• 대한설비공학회지:설비저널
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• 제17권4호
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• pp.377-381
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• 1988

Effects of thermal resistance of mold during freezing processes have been investigated. Saturated liquid is chosen to present one-dimensional quasi-steady solution and this solution is compared with numerical solutions. Front tracking finite element method has been applied for the numerical solutions. Results show that mold should be considered as well as phase change material except the cases when the very thin mold with relatively high thermal conductivity is used.

• Bulletin of the Korean Chemical Society
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• 제7권2호
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• pp.150-153
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• 1986

Co-sensitized photooxygenation of 1,1-diphenyl-2-vinylcyclopropane (VCP-DPh) with 9,10-dicyanoanthracene and biphenyl in oxygen-saturated acetonitrile solution produced 3,3-diphenyl-5-vinyl-1,2-dioxolane as the major product. The same photoproduct was obtained by acetone sensitized photooxygenation in oxygen-saturated acetone solution. However, VCP-DPh remained intact when directly irradiated with DCA or irradiated with Rose Bengal to generate singlet oxygen. A mechanism involving a cosensitizer radical cation and sensitizer radical anion is proposed.