• Journal of the Korean Data and Information Science Society
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• 제26권2호
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• pp.289-299
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• 2015

본 연구는 PM10 농도에 대한 계량치 예측모형 개발을 목적으로 한다. 세 종류의 자료 (기상관측 자료, 세계기상통신망 중국 관측자료, 대기질 화학수치모델자료)를 예측인자로 사용하였으며, 일일 단기예보 시스템에 쉽게 적용할 수 있도록 시간자료를 일자료로 변환하였고 시차변환을 수행하였다. 상관분석과 다중공선성 진단을 통하여 예측인자를 선택하고 두 종류의 모형 (중회귀모형, 문턱치 회귀모형)을 각각 적합하였다. 모형 안정성 검사를 위하여 모형검증을 수행하였으며, 전체자료를 사용하여 모형을 재추정한 후 예측치와 관측치 사이의 산점도와 시계열그림, RMSE, 예측성 평가측도를 작성 및 산출하여 두 모형을 비교하였다. 문턱치 회귀모형의 예측력이 고농도 PM10예측에서 다소 우수한 결과를 보였다.

• 한국세라믹학회지
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• 제32권11호
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• pp.1292-1300
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• 1995

The ionic conductivity of NASICON solid electrolytes was simulated by using Monte Carlo Method (MCM). There were included two conduction paths: (1) Na1-Na2 and (2) Na1-Na2 including Na2-Na2. We assumed that mid-Na ions provde an additional driving force for Na mobile ions due to the interionic repulsion between Na1 and Na2 ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, W increased rapidly with the composition at low temperature, but decreased at high temperature region. On Na1-Na2 conduction path, the minimum of charge correlation factor, fc and the maximum of $\sigma$T were appeared at x=2.0. this indicated that mid-Na ions affect on the high ionic conductivity behavior. At the whole range of NASICON composition, 1n $\sigma$T vs. 1/T* plots have been shown Arrhenius behavior but 1n (VWFc) vs. 1/T* have been shown the Arrhenius type tendency at x=2, which mid-Na is being the maximum. The results of MCM agreed with the experimental one when the chosen saddle point value was 6$\varepsilon$ : 3$\varepsilon$. Here the calculated characteristic parameter of materials, K and the phase transition temperature were -4.001$\times$103 and 178$^{\circ}C$ (1/T*=1.92, 1000/T=2.22), respectively.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.225-230
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• 2014

A kinetic study on nucleophilic substitution reactions of 4-nitrophenyl X-substituted-benzoates (7a-i) with EtOK in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$ is reported. The plots of pseudo-first-order rate constants ($k_{obsd}$) vs. [EtOK] curve upward. Dissection of $k_{obsd}$ into the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOK (i.e., $k_{EtO^-}$ and $k_{EtOK}$, respectively) has revealed that the ion-paired EtOK is more reactive than the dissociated $EtO^-$. Hammett plots for the reactions of 7a-i with the dissociated $EtO^-$ and ion-paired EtOK exhibit excellent linear correlations with ${\rho}_X$ = 3.00 and 2.47, respectively. The reactions have been suggested to proceed through a stepwise mechanism in which departure of the leaving-group occurs after the RDS. The correlation of the $k_{EtOK}/k_{EtO^-}$ ratio with the ${\sigma}_X$ constants exhibits excellent linearity with a slope of -0.53. It is concluded that the ion-paired EtOK catalyzes the reaction by increasing the electrophilicity of the reaction center rather than by enhancing the nucleofugality of the leaving group.

• Journal of Microbiology and Biotechnology
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• 제23권2호
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• pp.177-183
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• 2013

Bacterial blight, an important and potentially destructive bacterial disease in rice caused by Xanthomonas oryzae pv. oryzae (Xoo), has recently developed resistance to the available antibiotics. In this study, mass spectrometry (MS)-based metabolite profiling and multivariate analysis were employed to investigate the correlation between timedependent metabolite changes and antimicrobial activities against Xoo over the course of Phomopsis longicolla S1B4 fermentation. Metabolites were clearly differentiated based on fermentation time into phase 1 (days 4-8) and phase 2 (days 10-20) in the principal component analysis (PCA) plot. The multivariate statistical analysis showed that the metabolites contributing significantly for phases 1 and 2 were deacetylphomoxanthone B, monodeacetylphomoxanthone B, fusaristatin A, and dicerandrols A, B, and C as identified by liquid chromatography-mass spectrometry (LC-MS), and dimethylglycine, isobutyric acid, pyruvic acid, ribofuranose, galactofuranose, fructose, arabinose, hexitol, myristic acid, and propylstearic acid were identified by gas chromatography-mass spectrometry (GC-MS)-based metabolite profiling. The most significantly different secondary metabolites, especially deacetylphomoxanthone B, monodeacetylphomoxanthone B, and dicerandrol A, B and C, were positively correlated with antibacterial activity against Xoo during fermentation.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1089-1096
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• 2002

Solvolyses rate constants of trimethylacetyl chloride (2), isobutyryl chloride (3), diphenylacetyl chloride (4) and p-methoxyphenylacetyl chloride (5) in 2,2,2-trifluoroethanol (TFE)-water, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)-water and TFE-et hanol solvent systems at $10^{\circ}C$ are determined by a conductimetric method. Kinetic solvent isotope effects (KSIE) are reported from additional kinetic data for methanolyses of various substituted acetylchlorides in methanol According to the results of those reactions analyzed in terms of rate-rate profiles,extended Grunwald-Winstein type correlations, application of a third order reaction model based a general base catalyzed (GBC) and KSIE values. Regardless of the kind of neighboring groups (CH3- or Ph-groups) of reaction center, for aqueous fluorinated alcohol systems, solvolyses of 2, 3, 4, and 5 were exposed to the reaction with the same mechanism (a loose SN2 type mechanism by electrophilic solvation) controlled by a similarity of solvation of the transition sate (TS). Whereas, for TFE-ethanol solvent systems, the reactivity depended on whether substituted acetyl chloride have aromatic rings (Ph-) or alkyl groups (CH3-); the solvations by the predominant stoichiometric effect (third order reaction mechanism by GBC and/or by push-pull type) for Ph- groups (4 and 5) and the same solvation effects as those shown in TFE-water solvent systems for CH3- groups (2 and 3) were exhibited Such phenomena can be interpreted as having relevance to the inductive effect ( $\sigmaI)$ of substituted groups; the plot of log (KSIE) vs. ${\sigma}I$ parameter give an acceptable the linear correlation with r = 0.970 (slope = 0.44 $\pm$ 0.06, n = 5).

• 대한족부족관절학회지
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• 제20권4호
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• pp.145-151
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• 2016

Purpose: To evaluate the reliability of preoperative and postoperative distal metatarsal articular angle (DMAA) measurements and to determine whether such reliability is different in accordance with the foot and ankle fellowship and the number of years in practice. Materials and Methods: Between July 2012 and June 2014, a total of 20 patients (24 feet) were treated with proximal chevron osteotomy and distal soft tissue procedure for symptomatic hallux valgus deformity. DMAA were measured twice with an interval of two weeks between the preoperative and postoperative dorsoplantar radiographs by four observers; two of whom were foot and ankle surgeons (A and B), one knee surgeon, and one senior resident. The intraobserver reproducibility and interobserver reliability were assessed by intraclass correlation coefficients. Moreover, the limit of agreement between the preoperative and postoperative DMAA measurements were assessed using a Bland-Altman plot. Results: The intraobserver reproducibility of the foot and ankle surgeon A, knee surgeon, and senior resident improved from 0.796, 0.575, and 0.586 preoperatively to 0.968, 0.864, and 0.864 postoperatively, respectively. The interobserver reliability of foot and ankle surgeon A-B, foot and ankle surgeon A-knee surgeon, and foot and ankle surgeon A-senior resident improved from 0.874, 0.688, and 0.677 preoperatively to 0.971, 0.917, and 0.838 postoperatively, respectively. Conclusion: The intra- and interobserver reliabilities for DMAA measurement improved after proximal chevron osteotomy. Therefore, the necessity of additional procedures to correct the increased DMAA should be reevaluated after proximal chevron osteotomy in the hallux valgus with an increased DMAA.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2913-2917
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• 2009

Second-order rate constants (k$_{Nu–}$) have been measured for nucleophilic substitution reactions of Y-substituted phenyl benzoates (1a-i) with butane-2,3-dione monoximate ($Ox^-\;an\;\alpha$-nucleophile) and Z-substituted phenoxides in 80 mol% H$_2$O/20 mol% DMSO at 25.0${\pm}$0.1$^{\circ}C$. Hammett plots correlated with ${\sigma}^o$ and ${\sigma}^-$ constants for reactions of 1a-h with Ox$^–$ exhibit many scattered points. In contrast, the Yukawa-Tsuno plot results in a good linear correlation with ${\rho}_Y$ = 2.20 and r = 0.45, indicating that expulsion of the leaving group occurs in the rate-determining step (RDS). A stepwise mechanism with expulsion of the leaving-group being the RDS has been excluded, since Y-substituted phenoxides are less basic and better nucleofuges than Ox$^–$. Thus, the reactions have been concluded to proceed through a concerted mechanism. Ox$^–$ is over 10$^2$ times more reactive than its reference nucleophile, 4-chlorophenoxide (4-ClPhO$^–$). One might suggest that stabilization of the transition-state (TS) through intramolecular general acid/base catalysis is responsible for the ${\alpha}$-effect since such general acid/base catalysis is not possible for the corresponding reactions with 4-ClPhO$^–$. However, destabilization of the ground-state (GS) of Ox$^–$ has been concluded to be mainly responsible for the ${\alpha}$-effect found in this study on the basis of the fact that the magnitude of the ${\alpha}$-effect is independent of the nature of the substituent Y.

• 대한의생명과학회지
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• 제22권3호
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• pp.83-97
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• 2016

The measurement of viral load in HIV-1 infected patients is essential for the establishment of a therapeutic strategy. Several commercial assays have shown shortcomings in quantifying rare genotypes of HIV-1 such as minor groups of N and O. In this study, the HIV-1 RT-qPCR assay was developed. The primers and probe of HIV-1 were designed to target the pol gene and to increase the detection efficiency of various subtypes including group N and O. The HIV-1 quantitative RT-qPCR assay was assessed for its analytical performance and clinical evaluation. The LoD was determined to 33.9 IU/ml. The LoD of several subtypes including A, C, D, CRF_01AE, F, CRF_02AG, G and H, were determined to less than 40 IU/ml. The HIV-1 quantitative RT-qPCR assay was evaluated using the China National Reference Panel of HIV-1 RNA to determine the analytical performance. The results were all within the acceptable range. The clinical evaluation was performed at Hunan CDC in China. The clinical evaluation results were compared with those of the China domestic commercial kit. A significant correlation (fresh samples; $R^2=0.84$, P<0.001, frozen samples; $R^2=0.76$, P<0.001) between the two systems was observed for 64 fresh samples and 76 frozen samples with viral loads, and the Bland-Altman plot showed good agreement (98.4%, 96.1%, respectively). In conclusion, the HIV-1 quantitative RT-qPCR assay had comparable analytical performance with several commercial kits. The study provides basic data for the research of HIV-1 diagnosis and the development of P < HIV-1 molecular diagnostic assay.

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3543-3548
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• 2010

A kinetic study on nucleophilic displacement reactions of 2-pyridyl X-substituted benzoates 1a-e with potassium ethoxide (EtOK) in anhydrous ethanol is reported. Plots of pseudo-first-order rate constants ($k_{obsd}$) vs. $[EtOK]_o$ exhibit upward curvature. The $k_{obsd}$ value at a fixed $[EtOK]_o$ decreases steeply upon addition of 18-crown-6-ether (18C6) to the reaction mixture up to [18C6]/$[EtOK]_o$ = 1 and then remains nearly constant thereafter. In contrast, $k_{obsd}$ increases sharply upon addition of LiSCN or KSCN. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ has revealed that ion-paired EtOK is more reactive than dissociated $EtO^-$, indicating that $K^+$ ion acts as a Lewis acid catalyst. Hammett plots for the reactions of 1a-e with dissociated $EtO^-$ and ion-paired EtOK result in excellent linear correlation with $\rho$ values of 3.01 and 2.67, respectively. The $k_{EtOK}/k_{EtO^-}$ ratio increases as the substituent X in the benzoyl moiety becomes a stronger electron-donating group. $K^+$ ion has been concluded to catalyze the current reaction by stabilizing the transition state through formation of a 6-membered cyclic complex.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1525-1529
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• 2013

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for the nucleophilic substitution reactions of 2-pyridyl thionobenzoate (5b) with alkali-metal ethoxides (EtOM, $M^+=Li^+$, $Na^+$, $K^+$, and 18-crown-6-ether complexed $K^+$) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. $[EtOM]_o$ curve upward regardless of the nature of the $M^+$ ions, while those of $k_{obsd}/[EtO^-]_{eq}$ vs. $[EtO^-]_{eq}$ are linear with a positive intercept. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ (i.e., the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOM, respectively) has revealed that the ion-paired EtOM is more reactive than the dissociated $EtO^-$, and $M^+$ ions catalyze the reactions in the order $K^+$ < $Na^+$ < $Li^+$ < 18C6-complexed $K^+$. The plot of log $k_{EtOM}$ vs. $1/r_{Stokes}$ results in an excellent linear correlation, indicating that the reactions are catalyzed by the solvated $M^+$ ions but not by the bare $M^+$ ions. The reactions of 5b with EtOM have been concluded to proceed through a six-membered cyclic TS, in which the solvated $M^+$ ions increase the electrophilicity of the reaction center and the nucleofugality of the leaving group.