• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.68-71
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• 2004

Effects of surfactants and natural organic matter (NOM) on the sorption and reduction of tetrachloroethylene (PCE) and chromate with iron were examined in this study. PCE and chromate reduction by iron depended on the ionic type of the surfactants in this study. The apparent reaction rate constants of PCE with Triton X-100 and hexadecyltrimethyl ammonium (HDTMA) at one half and two times of the critical micelle concentration (CMC) were relatively higher than without surfactants because of the enhanced PCE partitioning and surface concentration. In the presence of sodium dodecyl benzene sulfonate (SDDBS) at 2000 mg/L and NOM at 50 mg/L, the apparent reaction rate constants of PCE increased, but TCE production decreased. The enhanced removal rate of PCE was not due to the dechlorination, and the sorption was dominant iron with SDDBS and NOM. The apparent reaction rate constants of chromate by iron with Triton X-100 and NOM were 1.4-3.1 times lower than without surfactants while that with HDTMA was two times higher than without HDTMA, When the sorbed HDTMA molecules form admicelles, negatively-charged chromate has an affinity for the positively-charged HDTMA head group.

• 한국기계가공학회지
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• 제19권3호
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• pp.77-85
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• 2020

In this study, we proposed a method to replace the solid finite element model of the boiler membrane wall for coal-fired power plants using an equivalent shell model. The application of a bending load to the membrane wall creates greater displacement at both ends of the central portion when compared with the middle when an isotropic elastic constant is used in the shell model. This is inconsistent with the results of the solid model where the central portion is uniformly deformed. Here, we presented a method to determine the orthotropic elastic constants of the shell model in terms of bending stiffness and vibration characteristics to solve this problem. Our analysis of the orthotropic shell model showed that the error ratio was 0.9% for the maximum displacement due to the bending load, 0.3% for the first natural frequency, and 2.5% for the second natural frequency when compared with the solid model. In conclusion, a complicated boiler membrane wall composed of a large number of pipes and fins can be replaced with a simple shell model that shows equivalent bending stiffness and vibration characteristics using our proposed method.

• 대한화학회지
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• 제31권6호
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• pp.503-508
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• 1987

3,4 : 9,10-dibenzo-1,12-diaza-5,8-dioxacyclotetradecane $(NenOenH_4)$과 전이금속이온$(Cu^{2+},\;Ni^{2+},\;Co^{2+},\;Zn^{2+},\;Mn^{2+})$과의 착물의 안정도상수를 50%다이옥산-수용액에서 이온강도를 0.1로 하고, 전위차법적정으로 측정한 결과, 전이금속이온과 리간드가 만드는 착물의 안정도상수의 순서는 Williams-Irving서열과 일치한다.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.809-812
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• 2004

Complexation reactions of nitrilotriacetate (NTA) and penicillamine with $Cu^{2+}$ and $Co^{2+}$ have been studied in solution phase using paper electrophoresis technique. The stability constants of the complexes Cu(II)-nitrilotriacetate-penicillamine and Co(II)-nitrilotriacetate-penicillamine have been found to be $6.64{\pm}0.03\;and\;5.86{\pm}0.05$ (logarithm stability constant values), respectively at 35$^{\circ}C$ and ionic strength 0.1 M.

• Structural Engineering and Mechanics
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• 제22권6호
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• pp.701-717
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• 2006

In the existing reports regarding free transverse vibrations of the Euler-Bernoulli beams, most of them studied a uniform beam carrying various concentrated elements (such as point masses, rotary inertias, linear springs, rotational springs, spring-mass systems, ${\ldots}$, etc.) or a stepped beam with one to three step changes in cross-sections but without any attachments. The purpose of this paper is to utilize the numerical assembly method (NAM) to determine the exact natural frequencies and mode shapes of the multiple-step Euler-Bernoulli beams carrying a number of lumped masses and rotary inertias. First, the coefficient matrices for an intermediate lumped mass (and rotary inertia), left-end support and right-end support of a multiple-step beam are derived. Next, the overall coefficient matrix for the whole vibrating system is obtained using the numerical assembly technique of the conventional finite element method (FEM). Finally, the exact natural frequencies and the associated mode shapes of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and substituting the corresponding values of integration constants into the associated eigenfunctions, respectively. The effects of distribution of lumped masses and rotary inertias on the dynamic characteristics of the multiple-step beam are also studied.

• 대한화학회지
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• 제31권5호
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• pp.434-443
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• 1987

Ln-EDTA 1 : 1 착물과 IMDA 사이의 착물형성에 대한 안정도 상수들을 이온세기 ${\mu}$ = 0.1, KNO$_3$와 20.0${\pm}$0.2$^{\circ}$C에서 전위차 적정법으로 연구하였다. Ln(EDTA)(IMDA) 혼합리간드착물들에 비교적 큰 안정도 상수가 형성된다는 사실을 밝혔으며, Ln원소들의 원자번호에 대한 형성도상수들의 경향을 Ln원소의 배위수와 반지름의 바탕에서 고찰하였다.

• 자연과학논문집
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• 제17권1호
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• pp.31-37
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• 2006

We have found that the polarization mode coupling between the orthogonally linearly polarized dual mode laser results from the anisotropy of dipole moments. Rate equation analysis demonstrated that high anisotropy in dipole moment components can give rise to law intrinsic mode coupling constants while isotropic dipole moment components give high intrinsic mode coupling constant. The populations at active ion sites are shown to self-organize the populations such that laser mode gain is constant adove threshold while the gain contributions from the each site adjust themselves with pump power.

• 대한수학회보
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• 제40권2호
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• pp.341-349
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• 2003

Let {$x_{nk}\;$\mid$1\;\leq\;k\;\leq\;n,\;n\;\geq\;1$} be an array of random varianbles and $\{a_n$\mid$n\;\geq\;1\}\;and\;\{b_n$\mid$n\;\geq\;1} be a sequence of constants with $a_n\;>\;0,\;b_n\;>\;0,\;n\;\geq\;1. In this paper, for array of row negatively associated(NA) random variables, we establish a general weak law of large numbers (WLLA) of the form (${\sum_{\kappa=1}}^n\;a_{\kappa}X_{n\kappa}\;-\;\nu_{n\kappa})\;/b_n$ converges in probability to zero, as $n\;\rightarrow\;\infty$, where {$\nu_{n\kappa}$\mid$1\;\leq\;\kappa\;\leq\;n,\;n\;\geq\;1$} is a suitable array of constants.

• 한국환경보건학회지
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• 제25권3호
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• pp.36-43
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• 1999

The present study was performed to investigate biodegradation rate of dichlorvos and methidathion. In the biodegradation test of two pesticides by the modified river die-away method from June 17 to August 22, 1998, the biodegradation rate constants and half-life were determined in Nakdong(A) and Kumho River(B). Biodegradation rate of dichlorvos was 4.51% in A sampling point, 6.88% in B sampling point after 7 days. Biodegradation rate constants and half-life of dichlorvos were 0.0066 and 105 days in A sampling point, 0.0102 and 67.9 days in B sampling point, respectively. Biodegradation rate of methidathion was 23% in A sampling point, 36% in B sampling point after 7 days. Biodegradation rate constants and half-life of methidathion were 0.0377 and 18.4 days in A sampling point, 0.0641 and 10.8 days in B sampling point, respectively. Biodegradation rate of methidathion was faster than that of dichlorvos. This suggested that the difference in biodegradation of pesticides was due to difference in the water quality and standard plate counts in the Nackdong and Kumho Rivers. The result of correlation analysis between biodegradation rate constants of the pesticides and water quality(DO, BOD, SS, ABS, NH$_3$-N, and NO$_3$-N) showed significant correlation with BOD, SS and NH$_3$-N at the 5% significant level. A significant linear equation was obtained from regression analysis at the 5% significant level, whereas, dependent variables were BOD, SS and NH$_3$-N, and the biodegradation rate constant was independent variable. It is suggested that dichlorvos will be mainly degraded by hydrolysis, and for methidathion was both hydrolysis and biodegradation. A significant QSAR equation was obtained from regression analysis at the 10% significant level, whereas, dependent variable is biodegradation rate constants of BPMC, chlorothalonil, dichlorvos and methidathion, vapor pressures, partition coefficients and water solubilities of the pesticides are independent variables. Also, a significant linear equation was obtained from regression analysis at the 1% significant level, whereas, dependent variable is biodegradation rate constants of BPMC, chlorothalonil, dichlorvos and methidathion, hydrolysis rate constants of the pesticides are independent variables. It is suggested that the pesticides will be degraded by main degradation factor when the pesticides was affected both hydrolysis and biodegradation.

• BMB Reports
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• 제30권1호
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• pp.7-12
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• 1997

The kinetics of the interesterification of triolein and stearic acid catalyzed by immobilized Rhizopus delemar lipase were studied in a batch operation. In order to clarify the mechanisms of this reaction, three models are discussed under various conditions in terms of the ratio of triolein and stearic acid. The rate constants involved in the proposed model were determined by combining the numerical Gauss-elemination method, and the trial-and-error method so as to fit the calculated results with the experimental data. The accuracy of the obtained rate constants was confirmed after they were substituted for simultaneous differential equations and the equations simulated using an adaptive step-size Runge-Kutta method. Finally, the model which agrees with the calculated results and the experimental data was selected.