• 한국토양비료학회지
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• 제34권3호
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• pp.213-236
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• 2001

토양용액의 이온조성은 작물의 양분흡수와 밀접한 관계를 가지고 있으며 양분의 이온조성을 추정하기 위하여 많은 모델이 개발되어 사용되고 있다. 토양용액 중 분석되는 양분의 몰농도는 insoluble 이온쌍과 평형을 이루고 있는 soluble 이온과 이온쌍 그리고 complex등의 농도로 간주하고, 양이온과 음이온을 동시에 고려한 양분의 이온조성을 추정하기 위하여 분석된 양분의 몰농도에 따른 선정된 평형식의 평형상수에 대한 conditional equilibrium constant를 구하여 모든 평형식이 만족되는 이온과 이온쌍의 몰농도를 구하는 모델을 설정하였다. 본 모델 이용시 기본적으로 필요한 성분은 pH, Eh, EC, 양이온 8종(K, Ca, Mg, Na, Fe, Mn, Al, $NH_4{^+}$, 음이온 6종(Si, 5, p Cl, $NO_3{^-}$, $HCO_3{^-}$)이며 다른 성분도 추가할 수 있도록 하였다. 토양과 토양용액이 평형조건인 경우 추정된 이온과 이온쌍의 조성과 이에 따른 존재 가능한 침전량과 mineral 종류별 함량을 계산하였다.

• 청정기술
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• 제20권1호
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• pp.35-41
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• 2014

본 연구에서는 입상 활성탄($8{\times}30mesh$, $1,578m^2/g$)을 사용하여 quinoline yellow 염료를 흡착하는데 필요한 흡착평형과 흡착동역학 및 열역학에 대하여 조사하였다. 등온흡착평형관계를 검토한 결과, 평가된 Langmuir 식의 상수($R_L=0.0730{\sim}0.0854$)와 Freundlich 식의 상수(1/n = 0.2077~0.2268)로부터 입상 활성탄에 의해 quinoline yellow를 적절하게 흡착처리 할 수 있음을 알았고, Temkin 식의 상수(B = 15.759~21.014 J/mol)와 Dubinin-Radushkevich 식의 상수(E = 1.0508~1.1514 kJ/mol)로부터 흡착공정이 물리흡착공정임을 알았다. 흡착공정에 대한 동력학적 해석을 통해 반응속도식의 적용결과는 유사이차반응속도식이 유사일차반응속도식에 비해 일치도가 높은 것으로 나타났으며, 흡착공정은 입자내세공확산과 표면확산의 두단계로 진행됨을 알았다. 유사이차반응속도식을 적용한 열역학적 해석을 통해 평가된 엔탈피 변화값(+35.03 kJ/mol)과 활성화에너지값(+35.137 kJ/mol)으로부터 흡착공정이 흡열반응으로 진행됨을 알았다. 또한 엔트로피 변화값(+134.38 J/mol K)은 흡착공정의 무질서도가 증가한다는 것을 나타내었고, 온도가 올라갈수록 자유에너지값이 감소하는 경향을 보인 것은 활성탄에 대한 quinoline yellow의 흡착반응은 온도가 올라갈수록 자발성이 높아지는 것으로 판단되었다.

• 한국환경과학회지
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• 제7권6호
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• pp.753-759
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• 1998

In physical and reactive extraction of acrylic acid using various solvents the equilibrium characteristics of extraction were investigated. The degree of extraction in reactive extraction with Tri-n-octylamine(TOA) was 1.5~3 times than that in physical extraction. Distribution ratio was constant in methyl isobutyl ketone(MIBK) and n-butylacetate(n-BAc) but was increased with increasing the concentration of acrylic acid in benzene and chloroform. It can be explained by formation of dimers. Maximum extraction leadings of acrylic acid were three in benzene and were two in MIBK, chloroform and n-BAc, and it was found that acrylic acid was extracted as the form of $A_3$R In benzene and $A_2R$ in MIBK, chloroform and n-BAc. In effect of solvent, the degree of extraction was increased as he difference of solubility parameter of solvent and solute was decreased, and as dielectric constant of solvent was increased.

• 환경위생공학
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• 제22권1호
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• pp.49-56
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• 2007

The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of metal ions by 1-aza-18-crown-6-styrene-DVB(divinylbenzene) resin(resin) adsorbent were investigated. The metal ions were showed fast adsorption on the resins in over pH 3. The equilibrium time for adsorption of metallic ions was about two hours and the adsorption selectivity determined in methanol was in increasing order $UO_2^{2+}>Mg^{2+}>Ho^{3+}$ ions. The adsorption was in the order of 1%, 2% and 4% crosslink resin and adsorption of resin decreased in proportion to the order of dielectric constant of solvents.

• 환경위생공학
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• 제17권3호
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• pp.31-36
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• 2002

The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of metal ions by resin(cryptand resin) adsorbent were investigated. The metal ions were showed fast adsorption on the resins in over pH 3. The equilibrium time for adsorption of metallic ions was about two hours and the adsorption selectivity determined in methanol was in increasing order $UO^{2+}$ > $Mn^{2+}$ > $Gd^{3+}$ ion. The adsorption was in the order of 1%, 2% and 5% crosslink resin and adsorption of resin decreased in proportion to the order of dielectric constant of solvents.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.381-386
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• 2007

The present study is concerned with the application of Constant arc-length method that proposed by Crisfield in the investigation of the geometrically nonlinear behaviour of spatial structures composed by truss or beam element. The arc-length method can trace the full nonlinear equilibrium path of Spatial structure far beyond the critical point such as limit or bifurcation point. So, we have developed the constant arc-length method of Crisfield to analysis spatial structure. The finite element formulation is used to develop the 3d truss/beam element including the geometrical nonlinear effect. In an effort to evaluate the merits of the methods, extensive numerical studies were carried out on a number of selected structural systems. The advantages of Constant arc length method in tracing the post-buckling behavior of spatial structures, are demonstrated.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4571-4584
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• 2022

The analysis of rapid flow transients in Reactor Coolant Pumps (RCP) is essential for a reactor safety study. An accurate and precise analysis of the RCP coastdown is necessary for the reactor design. The coastdown of RCP affects the coolant temperature and the colloidal crud in the primary coolant. A realistic and kinetic model has been used to investigate the behavior of activated colloidal crud in the primary coolant and steam generator that solves the pump speed analytically. The analytic solution of the non-dimensional flow rate has been determined by the energy ratio β. The kinetic energy of the coolant fluid and the kinetic energy stored in the rotating parts of a pump are two essential parameters in the form of β. Under normal operation, the pump's speed and moment of inertia are constant. However, in a coastdown situation, kinetic damping in the interval has been implemented. A dynamic model ACCP-SMART has been developed for System Integrated Modular and Advanced Reactor (SMART) to investigate the corrosion due to activated colloidal crud. The Fickian diffusion model has been implemented as the reference corrosion model for the constituent component of the primary loop of the SMART reactor. The activated colloidal crud activity in the primary coolant and steam generator of the SMART reactor has been studied for different equilibrium corrosion rates, linear increase in corrosion rate, and dynamic RCP coastdown situation energy ratio b. The coolant specific activity of SMART reactor equilibrium corrosion (4.0 mg s^-1) has been found 9.63×10^-3 µCi cm^-3, 3.53×10^-3 µC cm^-3, 2.39×10^-2 µC cm^-3, 8.10×10^-3 µC cm^-3, 6.77× 10^-3 µC cm^-3, 4.95×10^-4 µC cm^-3, 1.19×10^-3 µC cm^-3, and 7.87×10^-4 µC cm^-3 for ²⁴Na, ⁵⁴Mn, ⁵⁶Mn, ⁵⁹Fe, ⁵⁸Co, ⁶⁰Co, ⁹⁹Mo, and ⁵¹Cr which are 14.95%, 5.48%, 37.08%, 12.57%, 10.51%, 0.77%, 18.50%, and 0.12% respectively. For linear and exponential coastdown with a constant corrosion rate, the total coolant and steam generator activity approaches a higher saturation value than the normal values. The coolant and steam generator activity changes considerably with kinetic corrosion rate, equilibrium corrosion, growth of corrosion rate (ΔC/Δt), and RCP coastdown situations. The effect of the RCP coastdown on the specific activity of the steam generators is smeared by linearly rising corrosion rates, equilibrium corrosion, and rapid coasting down of the RCP. However, the time taken to reach the saturation activity is also influenced by the slope of corrosion rate, coastdown situation, equilibrium corrosion rate, and energy ratio β.

• 암석학회지
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• 제2권2호
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• pp.139-155
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• 1993

We have shown that the volcanic rocks from the northern part of Cheju Island can be divided into high $P_2O_5/K_2O$(HPK) and low $P_3O_5/K_2O$(LPK) groups, each with distinct geochemical characteristics(Park and Kwon, 1993a and b). This study reports mineral compositions for plagioc-lase, olivine, and clinopyroxene in order to see the dependence of mineral chemistry on the whole rock composition, and discusses equilibrium relationships between crystal and liquid. Plagioclase and olivine phenocrysts show no compositional differences for the two rock group. However, $Al^{ⅵ}/Al^{ⅳ}$ ratios of clinopyroxenes suggest that pyroxenes have fractionated at deeper level, and that the LPK group might have fractionated at higher pressure than the HPK group. These are in good agreement with our previous interpretation based on whole rock chemistry(Park and Kwon, 1993a). Although subhedral or euhedral form and homogenous composition for most plagioclase and clinopy-roxene phenocrysts suggest equilibrium relationship with liquid, the uncertainties associated with liquid, the uncertainites associated with equilibrium constant for these minerals do not allow testing equilibium relationship between mineral and liquid on the basis of chemistry. On the other hand, olivine phenocrysts in hawaiites, for which Kd is well known, show distinct nonequilibrium relationship with calculated liquid composi-tions, while those in other rock compositions are in equilibrium from those for other rocks. We report for the first time as far as we know plagioclase xenocryst and pigeonite inclusion in plagioclase, which indicates assimilation process. In conclusion, these mineralogical observations imply that mag-matic processes underneath the Cheju volcano were not simple.

• Elastomers and Composites
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• 제14권4호
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• pp.231-252
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• 1979

Polymerization of 2-pyrrolidone was carried out through anionic mechanism using $SO_2/KOH$ as catalyst. The effects of KOH concentration, $SO_2/KOH$ mole ratio and temperature on polymerization were investigated. The conversion and viscosity of polymers were measured at various polymerization conditions. It was observed that as the concentration of KOH was increased, equilibrium conversion was also increased. It was, however, found that after the concentration of KOH was reached above 8 mole percent, the equilibrium conversion was decreased. The highest rate of polymerization and maximum conversion were obtained when $SO_2/KOH$ mole ratio was around 0.5. It was also found that the rate of polymerization and the equilibrium conversion were higher at $50^{\circ}C$. than at $30^{\circ}C$. but the viscosity of polymer solution at $50^{\circ}C$. was not so high as expected. The rate constant, $K_p$ of polymerization, was determined by least square method: the value of $K_p$ was observed as 16 liter/mole hour at $50^{\circ}C$. and 2.6 liter/mole hour at $30^{\circ}C$., respectively. The mechanism of polymerization was also discussed.

• 에너지공학
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• 제2권3호
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• pp.308-314
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• 1993

15mbar 정합하에서 n.dodecane-1.decanol-1.dodecanol 혼합물의 삼성분계 및 각 이성분계의 기액평형 데이타와 비점을 측정하였다. 측정된 기액평형 데이타는 g$^{E}$ 모델식 인 Margules, van Laar, Wilson, NRTL, UNIQA 식에 의해 상관관계를 알아보았다. 이성분계 데이타는 Redlich-Kister의 적분법에 의해 열역학적으로 검토하였으며, 삼성분계 데이터 역시 McDermott-Ellis에 의한 two-point consistency test에 의해 질적으로 검토되었다. 이성분계의 기액평형 데이타 중에 n.dodecane-1.decanol계 만이 공비점을 보였다.