• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2403-2407
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• 2009

Second-order rate constants have been measured for two series of nucleophilic displacement reactions, i.e., reactions of 4-nitrophenyl benzoate with Z-substituted phenoxides and those of Y-substituted phenyl benzoates (1a-h) with 4-chlorophenoxide (4-ClPhO–) in 80 mol% $H_2O$/20 mol% DMSO at 25.0 ${\pm}\;0.1\;{^{\circ}C}$. The Br$\phi$nsted-type plot for reactions of 4-nitrophenyl benzoate with Z-substituted phenoxides exhibits an excellent linear correlation with ${\beta}_{nuc}$ = 0.72. Reactions of 1a-h with 4-chlorophenoxide result in also a linear Br$\phi$nsted-type plot with ${\beta}_{lg}$ = –0.62, a typical ${\beta}_{lg}$ value for a concerted mechanism. The Hammett plots correlated with ${\sigma}^o\;and\;{\sigma}^-$ constants show many scattered points for reactions of 1a-h with 4-chlorophenoxide. In contrast, the corresponding Yukawa-Tsuno plot exhibits an excellent linear correlation with $\rho_Y$ = 2.26 and r = 0.53, indicating that expulsion of the leaving group occurs at the rate-determining step (RDS) either in a concerted mechanism or in a stepwise pathway. However, a stepwise mechanism with leaving group departure being the RDS is excluded since the leaving Y-substituted phenoxide is less basic and a better nucleofuge than the incoming 4-ClPh$O^-$. Thus, the reactions have been concluded to proceed through a concerted mechanism, in which bond formation between the nucleophile and electrophilic center is more advanced than expulsion of the leaving group in the transition state on the basis of the magnitude of ${\beta}_{nuc}\;and\;{\beta}_{lg}$ values.

• Bulletin of the Korean Chemical Society
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• 제29권7호
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• pp.1359-1363
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• 2008

Second-order rate constants have been determined spectrophotometrically for reactions of 2,4-dinitrophenyl 2- thiophenecarboxylate (2) with a series of alicyclic secondary amines in 80 mol % $H_2O$/20 mol % DMSO at 25.0 ${\pm}$ 0.1 ${^{\circ}C}$. The Brønsted-type plot exhibits a downward curvature, i.e., the slope decreases from 0.74 to 0.34 as the amine basicity increases. The $pK_a$ at the center of the Brønsted curvature, defined as $pK_a^o$, has been determined to be 9.1. Comparison of the Brønsted-type plot for the reactions of 2 with that for the corresponding reactions of 2,4-dinitrophenyl 2-furoate (1) suggests that reactions of 1 and 2 proceed through a common mechanism, although 2 is less reactive than 1. The curved Brønsted-type plot has been interpreted as a change in RDS of a stepwise mechanism. The replacement of the O atom in the furoyl ring by an S atom (1 $\rightarrow$ 2) does not alter the reaction mechanism but causes a decrease in reactivity. Dissection of the apparent second-order rate constants into the microscopic rate constants has revealed that the $k_2/k_{-1}$ ratio is not influenced upon changing the nonleaving group from furoyl to thiophenecarbonyl. However, $k_1$ has been calculated to be smaller for the reactions of 2 than for the corresponding reactions of 1, indicating that the C=O bond in the thiophenecarboxylate 2 is less electrophilic than that in the furoate 1. The smaller k1 for the reactions of 2 is fully responsible for the fact that 2 is less reactive than 1.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2455-2460
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• 2013

Second-order rate constants ($k_N$) have been measured spectrophotometrically for the nucleophilic displacement reactions of 4-nitrophenyl X-substituted-cinnamates (4a-4e) and Y-substituted-phenyl cinnamates (5a-5e) with Z-substituted-phenoxide anions in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$. The Hammett plot for the reactions of 4a-4e with 4-chlorophenoxide (4-$ClPhO^-$) consists of two intersecting straight lines, which might be taken as a change in the rate-determining step (RDS). However, it has been concluded that the nonlinear Hammett plot is not due to a change in the RDS but is caused by stabilization of the ground state of substrates possessing an electron-withdrawing group in the cinnamoyl moiety through resonance interactions, since the Yukawa-Tsuno plot exhibits an excellent linear correlation with ${\rho}X=0.89$ and r = 0.58. The Br${\o}$nsted-type plot for the reactions of 4-nitrophenyl cinnamate (4c) with Z-substituted-phenoxides is linear with ${\beta}_{nuc}=0.76$. The Br${\o}$nsted-type plot for the reactions of Y-substituted-phenyl cinnamates (5a-5d) with 4-chlorophenoxides (4-$ClPhO^-$) is also linear with ${\beta}_{lg}=-0.72$. The Hammett plot correlated with ${\sigma}^-$ constants for the reactions of 5a-5d results in a much better linear correlation than that correlated with ${\sigma}^o$ constants, indicating that a partial negative charge develops on the O atom of the leaving aryloxide. Thus, the reactions have been concluded to proceed through a concerted mechanism.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2325-2329
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• 2013

Second-order rate constants $k_N$ have been measured for reactions of benzyl 2-pyridyl thionocarbonate (4b) and t-butyl 2-pyridyl thionocarbonate (5b) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. The $k_N$ values for the reactions of 4b and 5b have been compared with those reported previously for the corresponding reactions of benzyl 2-pyridyl carbonate (4a) and t-butyl 2-pyridyl carbonate (5a) to investigate the effect of changing the electrophilic center from C=O to C=S on reactivity and reaction mechanism. The thiono compound 4b is more reactive than its oxygen analogue 4a. The Br${\o}$nsted-type plots for the reactions of 4a and 4b are linear with ${\beta}_{nuc}=0.57$ and 0.37, respectively. The reactions of 4a were previously reported to proceed through a concerted mechanism, while those of 4b in this study have been concluded to proceed through a stepwise mechanism with formation of an intermediate being the rate-determining step on the basis of the ${\beta}_{nuc}$ value of 0.37. Enhanced polarizability upon changing the C=O in 4a by C=S has been suggested to be responsible for the reactivity order and the contrasting reaction mechanisms. In contrast, the reactivity of 5a and 5b is similar, but they are much less reactive than 4a and 4b. Furthermore, the reactions of 5a and 5b have been concluded to proceed through the same mechanism (i.e., a concerted mechanism) on the basis of linear Bronsted-type plots with ${\beta}_{nuc}=0.45$ or 0.47. It has been concluded that the strong steric hindrance exerted by the t-Bu in 5a and 5b causes a decrease in their reactivity and forces the reactions to proceed through a concerted mechanism.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제10권11호
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• pp.465-472
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• 2021

본 논문에서는 약물의 시판 후 이상 반응을 모니터링하기 위해 약물 리뷰 데이터로부터 약물 이상 반응을 탐지할 수 있는 방법을 제시하였다. 부정적인 약물 리뷰는 주로 약물 이상 반응을 언급하고 있다는 점을 고려하여 약물 리뷰들을 감성 분석하여 부정 리뷰를 추출하고, 부정 리뷰에 사전 기반 추출과 개체명 인식 기법을 적용하여 약물 이상 반응을 탐지하였다. 제안하는 BERT+ 알고리즘으로 부정 리뷰를 판별한 다음, MedDRA 표준 의학 용어 사전을 활용해 이상 반응 단어를 찾고, 개체명 인식 기법을 사용하여 구로 표현된 이상 반응 표현을 탐지하였다. 실험을 위해 비스테로이드성 소염진통제 세 종류의 약물 리뷰를 약물 리뷰 사이트로부터 수집하여 테스트하였으며, 실험 결과는 약물 리뷰를 통한 약물 이상 반응 탐지가 현재의 약물 감시 체계의 한계점을 보완할 수 있음을 보여준다.

• 대한한의학회지
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• 제28권2호통권70호
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• pp.66-79
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• 2007

Objectives : To explore the type and frequency of short term reactions, de Qi associated with acupuncture treatment and to determine the incidence of adverse events following acupuncture in Korea. Subjects and methods : This study is a retrospective and cross-sectional survey of patient reports. 1095 subjects, 585 of out-patients of the Oriental Medicine of Stroke & Neurological Disorders Center, East-West NEO Medical Center of Kyunghee University and 510 of out-patients of the Department of Cardiovascular & Neurologic Diseases (Stoke Center), Hospital of Oriental Medicine, Kyunghee Medical Center, from June through November of 2006, who had acupuncture, gave informed consent and completed one survey form. On this form, patients were asked to report short term acupuncture reactions, de Qi, patient satisfaction measurement (using VAS), and adverse events relating to acupuncture treatment. The acupuncturists of this study are Korean Medicine Doctors (KMD) who had worked as practitioners for 3-30 years or more. Results : The average age of the 1095 subjects was 58 years old. Positive short term acupuncture reactions after treatment were reported by 878 (80.2%), negative short term acupuncture reactions by 75 (6.8%) and no reactions were reported by 142 (13.0%). The most common positive short term acupuncture reactions were feeling 'relaxed', 472 (43.1%), followed by feeling 'less pain' 90 (8.2%), 'energized' 16 ( 1.5%), 'tingling' 16 (1.5%), 'heat feeling or Cold feeling' 10 (0.9%), and others 274 (25.0%), respectively. Negative short term acupuncture reactions were feeling 'pain' 37 (3.4%), tiredness 24 (2.2%), dizziness 9 (0.8%), and others 5 (0.2%), respectively. Traditionally described needling sensations of de Qi refer to a patient's response to distention, pulling, soreness, heaviness, numbness. 39.7% of subjects reported de Qi during needling, experiencing 'distention' 333 (30.4%), 'soreness' 52 (4.7%), 'pulling' 22 (2.0%), 'heaviness' 18 (1.6%), and 'numbness' 10 (0.9%) respectively. Positive short term acupuncture reactions and de Qi rate were the highest in the less than 40 years group (83/96 86.5%, 50/96 52.1%). No acupuncture reactions were highly seen in the over 70 years old group (31/187, 16.6%). Patient satisfaction level using VAS was a comparatively high $72.9{\pm}19.9$. Adverse events were only bleeding in 92 (8.4%) of the total subjects. High sensitive acupoints were 95 points as GV26 (54 times), LI4 (54 times), ST36 (53 times), GB20 (37 times), HT8(34 times), LV3 (29 times), SI3 (29 times), and LI11 (27 times) in order. Main impressions were stroke patients 430 (16.9%), headache 185 (16.9%), hypertension 97 (8.9%), and dizziness 85 (7.8%). Conclusions : Although 8 different Korean Medicine Doctors participated in this research, we obtained similar results from each. There were no significantly different results between the two hospitals. Short term acupuncture reactions and de Qi were most related to age. Except for bleeding there were no adverse events relating to acupuncture treatment in this study. We consider acupuncture treatment as very safe depending on practitioners. Positive short term acupuncture reactions after treatment were 12 times higher than negative short term acupuncture reactions. Subjects were comparatively satisfied with acupuncture treatment.

• Journal of Applied Biological Chemistry
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• 제48권2호
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• pp.105-107
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• 2005

• 대한임상약리학회:학술대회논문집
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• 대한임상약리학회 2002년도 제11차 추계학술대회
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• pp.11-11
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• 2002

• Investigative Magnetic Resonance Imaging
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• 제15권2호
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• pp.139-145
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• 2011

목적 : 단일기관에서 발생한 가돌리니움 기반의 자기공명영상 경정맥 조영제의 급성 부작용의 빈도 및 종류, 조영제 별 차이를 알아보았다. 대상 및 방법 : 병원정보시스템의 부작용 보고체계를 분석하여, 2008년 10월부터 2010년 12월 사이에 증례를 검색하였다. 부작용은 경증, 중등도, 중증으로 분류되었고 서로 다른 조영제간에 빈도의 차이가 있는지를 분석하였다. 결과 : 총 33,600건의 조영제가 투여되었고, Gd-BT-DO3A 20,824건 (62%), Gd-DTPA 10,417건 (31%), Gd-EOB-DTPA 2,359건 (7%)이었다. 부작용은 총 39예가 발생하여 빈도는 0.1161%였고, Gd-BT-DO3A 0.1248% (26/39,67%), Gd-DTPA 0.0768% (8/39, 21%), Gd-EOB-DTPA 0.2120% (5/39,13%) 였으며, 조영제 간에 유의한 차이는 없었다. 대부분 (89.7%) 이 경증 부작용이었으며 중등도 및 중증 부작용은 각각 2명에서 발생하였다. 결론 : 한국인에서의 자기공명영상 검사용 경정맥 조영제에 의한 부작용의 빈도는 드물었으며, 특히 중등도 혹은 중증 부작용은 매우 드물었다. 세가지 조영제 사이에 부작용 발생 빈도는 차이는 없었다.

• 한국항공우주학회지
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• 제48권3호
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• pp.195-205
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• 2020

본 논문은 항공기 전기체 구조시험에서 6개 자유도를 구속하는 자세구속시스템에서 발생하는 반력들 분석에 대해 다루고 있다. 반력에는 시험의 모든 오차(제어오차와 기타시험오차)를 포함하고 있으므로 반력분석을 통한 시험오차를 평가하는 연구가 의미가 있고 이를 위해서는 우선 바른 반력산출이 우선되어야 하고 바른 반력산출이 본 연구의 초점이다. 본 연구에서 반력을 공칭반력(Rn)과 시험오차반력(Rce, Rerr)의 합으로 표시할 것을 제시하였고 초기상태(0%DLL)에서 이미 내포한 시험오차특성과 하중증분에 따라 발생하는 시험오차특성을 구분하기 위해 반력을 초기상태반력과 상대 반력으로 구분하여 분석하였다. 선미익기 전기체 구조시험 데이터를 활용하여 정량적 반력분석 결과 제어오차로 인한 반력(Rce)값은 전 하중레벨에서 크기변화가 크지 않으며, 합성력 크기가 82.8N 이내로 유지되었고, 이는 하중부가 전체널에 대한 제어오차(TMF)가 -30~40N 범위 내에서 큰 변화 없이 유지되기 때문이다. 상대반력분석을 통해 산출된 기타시험오차(Rerr_r)의 합성력 크기는 하중 증분에 따라 증대되며, 그 크기도 Rce_r보다는 매우 크게 증대됨(최대치808N)을 보여주었고 바른 상대반력 산출을 위해서는 시험체 변형을 고려해야 함을 각 성분별(X0, Y0, Z0) Rerr_r 분석을 통해 보였다. 시험체 변형을 고려한 반력산출은 시험체에 가해지는 힘들의 작용점 이동을 산출할 수 있는 시험체 변형특성식을 요구한다는 것을 보였다.