4-치환 Phenyl Ethyl Benzylphosphonate의 알칼리 가수분해 반응에 대한 속도론적 연구

손경화,박경곤,이부영,신갑철,Shon, Kyoung Hwa,Park, Kyung Kone,Lee, Bu Young,Shin, Bu Young 대한화학회 1997 대한화학회지 Vol.41 No.6

4-치환 Phenyl ethyl benzylphosphonate의 알칼리 가수분해 반응에 대한 속도 상수($k_{OH}$)를 UV-Vis 분광 광도계로서 결정하였다. 활성화 엔트로피(${\Delta}S^{\neq}$)값은 큰 음의 값을 가졌으며 이 결과는 활성화 엔트로피가 양의 값이나 작은 음의 값으로 기대되는 해리 반응(EA)과 일치하지 않았고 좋은 Hammett 상관 관계식으로부터 속도결정단계에서 이탈기에 의해 음의 전하가 거의 발생하지 않는 회합성(AE) 메커니즘이 일어남을 강력히 암시하고 있다. 반응속도론적 연구 결과에 의하면 4-치환 Phenyl ethyl benzylphosphonate의 가수분해 반응은 해리 메커니즘으로 진행되지 않음을 알 수 있었다. The rate constants($k_{OH}$) for the alkaline hydrolysis of the 4-substituted phenyl ethyl benzylphosphonates were determined in various buffer solutions by UV(Vis spectrophotometer. The activation entropies of the title reactions show negative values and this result is not consistent with a dissociative mechanism (EA) for which a positive or slightly negative value of the entropy of activation should be expected. An associative mechanism(AE) is favorable because the negligible negative charge is generated on the leaving group in the rate determining step from a good Hammett relationship(ρ=1.89). By the results of a kinetic study, we conclude that a dissociative mechanism is not proceeded in the title reactions.

배달서비스 구매결정과정에서 신뢰와 브랜드 이미지의 조절효과에 관한 연구 -카페 카테고리를 중심으로-

손경화 한국외식산업학회 2023 한국외식산업학회지 Vol.19 No.3

The current study examined the impact of the quality of food delivery services on customer satisfaction and repurchase intentions. The study further investigated whether brand image and trust, which have been found to be important factors in previous studies, played a positive moderating role between delivery service quality and customer satisfaction. Three key findings were identified as follows. First, the analysis of the four factors of food delivery service quality indicated that delivery service quality had the most significant impact on customer satisfaction. In addition, system quality and food quality were found to influence customer satisfaction positively. However, these findings suggest that safety quality does not have any effect on customer satisfaction. Second, customer satisfaction with food delivery services was found to have a highly significant effect on purchase intention in statistical terms. Lastly, the moderated regression analysis, which was conducted to examine the moderating effects of brand image on the relationship between food delivery service quality and customer satisfaction, indicated that there was no moderating effect. Furthermore, the examination of the moderating effects of value on the relationship between food delivery service quality and customer satisfaction suggested that the moderating effects of value existed in delivery quality, safety quality, and food quality.

홀뮴 및 홀뮴-키토산 복합체가 정상 백서 뇌에 미치는 효과에 대한 연구

손경화,조철우,안영환,박찬희,심철,박경배,조경기,Sun, Jing He,Joh, Chul W,Ahn, Young Hwan,Park, Chan Hee,Shim, Chull,Park, Kyung Bae,Cho, Kyung Gi 대한신경외과학회 2000 Journal of Korean neurosurgical society Vol.29 No.10

Objectives : We performed an in vivo experiment to investigate the effect of $^{166}Holmium$ and $^{166}Holmium$-chitosan complex($^{166}Ho$-CHICO) on the normal brain of rats and to determine the sublethal dose of $^{166}Ho$-CHICO. Materials and Methods : $^{166}Ho$ is a beta and gamma ray emitter. $^{166}Ho$-CHICO is a novel radio-pharmaceutical complex with chitosan to facilitate the transport of $^{166}Ho$ obtained from Korea Atomic Energy Research Center(Taejon, Korea). It is in acidic form and becomes gel state at alkaline pH. One hundred and seventy consecutive rats were divided into four groups : $^{166}Ho$ treated(n=50), $^{166}Ho$-CHICO treated(n=57), saline treated(n=5) and chitosan treated(n=5) groups. $^{166}Ho$ and $^{166}Ho$-CHICO were injected into the rat brain stereotactically with various doses of 0.1mCi/$20{\mu}l$, 0.2mCi/$20{\mu}l$, 0.3mCi/$20{\mu}l$, and 0.4mCi/$20{\mu}l$ using an automated microinjector. Nuclear imaging, histopathological and hematological studies were performed in 10 rats in each group at 1 day, 3days, 7 days, 1 month and 3 months after the injections. Results : An infiltration of inflammatory cells and necrotic changes were noted in $^{166}Ho$ treated group at 1 week after the injection. A wedge-shaped tissue defect due to necrosis, lined with infiltrated glial cells in $^{166}Ho$ treated group and a cystic defect lined with reactive astroglial cells in $^{166}Holmium$-CHICO treated group at 3 months after the injection were observed. $^{166}Ho$ alone without chitosan leaked out and caused necrotic lesion on the cerebral surface but $^{166}Holmium$-CHICO treated group did not show this feature. As the dose of $^{166}Ho$ increased, the mortality rates were also increased. The mortality rate of the $^{166}Holmium$-CHICO group was higher than the $^{166}Ho$ treated group at a dose of 0.4mCi/$20{\mu}l$/300g. There was no detectable radioactivity due to the leakage or extravasation from the injected site of the brain on the scintigraphy performed at 1 hour, 24 hours and 48 hours after the injection. There was also no detectable activity of $^{166}Holmium$-CHICO in other organs including spleen, liver and kidney. Conclusions : $^{166}Ho$-CHICO did not leak out to the critical cortical surface of the brain from the injection site and induced radiation changes of the parenchyma around the injection site without cortical damage. The sublethal dose of $^{166}Ho$-CHICO for the normal brain in rats was determined to be 0.2mCi/$20{\mu}l$/300g.

치환 Phenyl N,N-diethyl-P-benzylphosphonamidates의 염기성 가수분해 반응에 대한 속도론적 연구

손경화,신갑철,Shon, Kyoung Hwa,Shin, Gap Cheol 대한화학회 1999 대한화학회지 Vol.43 No.1

Phenyl N,N-diethyl-P-benzylphonamidate 및 그 유도체들의 염기성 가수분해 반응속도 상수를 분광 광도법으로 측정하였다. 속도 상수로부터 열역학적 파라메타(Ea, ${\Delta}H^{\neq}$,${\Delta}S^{\neq}$)를 구하였고, 이탈기의 치환기 효과는 Hammett 식을 이용하여 얻었다. 이들 실험 자료에 의하면 가수분해 반응은 활성화 엔트로피가 양의 값이나 작은 음의 값을 갖고 카르보음이온 생성이 수반되는 해리반응 보다는 이중피라미드 중간체 또는 전이 상태를 경유하는 회합 메카니즘을 강력히 암시하고 있다. 반응속도론적 연구 결과에 의하면 치환 pheny N,N-diethyl-P-benzylphosphonamidates의 가수분해 반응은 회합성 메카니즘으로 진행됨을 알 수 있었다. The second order rate constants for the hydrolysis of substituted phenyl N,N-diethyl-P-benzylphosphonamidates (2,4-$(NO_2)_2$, 4-$NO_2$, 4-CN, 4-Cl, 4-H)in 20% dioxane-water (v/v) have been determined by UV/Vis spectrophotometric method at various temperatures. The activation parameters (Ea, ${\Delta}H^{\neq}$,${\Delta}S^{\neq}$) were calculated from the rate constants and the reaction constant ($\rho$) was also estimated by Hammett equation. The activation entropies of the title reactions show considerably negative values, this result is not consistent with a dissociative mechanism (EA) in which a positive or a slightly negative value of the entropy of activation should be expected. Further, kinetic evidence for an associative mechanism (AE) was obtained from the linear free energy relationship. By the results of kinetic study for the alkaline hydrolysis of substituted phenyl N,N-diethyl-P-benzylphosphonamidates, it may be concluded that these reactions proceed through an associative mechanism.

Synthesis and Application of Triphenylsulfonium triflate Containing PMMA-Based Resist for Lithography

손경화,김민정,이해원 한국고분자학회 2011 한국고분자학회 학술대회 연구논문 초록집 Vol.2011 No.1

밥 짓던 감각으로

손경화[기:잉] 한국여성민우회 2012 함께가는 여성 Vol.208 No.-

영아기 자녀를 둔 어머니의 취업과 보육선택

손경화 ( Kyeng Hwa Shon ),조복희 ( Bok Hee Cho ) 대한가정학회 2010 Human Ecology Research(HER) Vol.48 No.7

This study examine the employment and childcare choices of mothers of infants. Study participants were 543 mothers, with infants younger than 40 months, in Suncheon. The results were as follows. First, mothers` employment beliefs, regardless of whether they worked outside the home, showed more positive scores regarding employment when they had jobs and/or higher educational levels. Second, mothers` use of child-care was more likely to begin when their children were at younger ages when the mothers worked outside the home, had higher educational levels and/or perceived their employment circumstances as including the ideas "Always have internal conflicts over whether to quit the job or not" and/or "Have never thought of quitting the job". Third, we examined how the features of the childcare environment and childcare type affected the mothers.

취업신념 측정척도 개발과 타당화 연구

손경화 ( Kyeng Hwa Shon ),조복희 ( Bok Hee Cho ) 대한가정학회 2009 Family and Environment Research Vol.47 No.2

의자가 되는 법

손경화(Kyoughwa Son),송재상 한국독립영화협회 2016 한국독립영화협회 기타간행물 Vol.- No.-

간호대학생의 학업스트레스 및 임상실습스트레스가 문제음주 양상에 미치는 영향

최우중, 김현정, 권채연, 김은지, 손경화, 유현아, 허연주, 권민 水原大學校 2019 論文集 Vol.33 No.-

Purpose: The study was to identify degree and relationship between of problem drinking, academic stress and clinical practice stress in university students of nursing. The data was collected using questionnaires targeting university nursing students. Methods: Date collection was done between June 16, 2017 and July 31, 2017, and collected total 259 copies. Data was analyzed by using descriptive statistics, t-test, ANOVA and Pearson’s Correlation. Results: There was found significant positive correlation between academic stress and clinical practice stress in university students of nursing.(r=0.355, p<.001) And there was no significant correlation between of problem drinking, academic stress and clinical practice stress. Also, stress score of clinical practice in group of problem drinking is significantly lower than that of group of non drinking problem.(p=.045) Conclusions: To reduce clinical practice stress in group of non drinking problem and to develop alternative coping instead of drinking for group of drinking problem, nursing intervention is required.