• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2410-2414
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• 2014

A kinetic study is reported on nucleophilic substitution reactions of Y-substituted-phenyl picolinates (7a-7h) with a series of cyclic secondary amines in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$. Comparison of the kinetic results with those reported previously for the corresponding reactions of Y-substituted-phenyl benzoates (1a-1f) reveals that 7a-7h are significantly more reactive than 1a-1f. The Br${\o}$nsted-type plot for the aminolysis of 4-nitrophenyl picolinate (7a) is linear with ${\beta}_{nuc}=0.78$, which is typical for reactions proceeding through a stepwise mechanism with expulsion of the leaving group being the rate-determining step. The Br${\o}$nsted-type plots for the piperidinolysis of 7a-7h and 1a-1f are also linear with ${\beta}_{lg}=-1.04$ and -1.39, respectively, indicating that the more reactive 7a-7h are less selective than the less reactive 1a-1f to the leaving-group basicity. One might suggest that the enhanced reactivity of 7a-7h is due to the inductive effect exerted by the electronegative N atom in the picolinyl moiety, while the decreased selectivity of the more reactive substrates is in accord with the reactivity-selectivity principle. However, the nature of intermediate (e.g., a stabilized cyclic intermediate through the intramolecular H-bonding interaction for the reactions of 7a-7h, which is structurally not possible for the reactions of 1a-1f) is also responsible for the enhanced reactivity with a decreased selectivity.

• 보건행정학회지
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• 제19권4호
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• pp.78-97
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• 2009

This study examined the factors related to family caregiver satisfaction with institutional care services for beneficiaries under the Public Long-Term Care Insurance(PLTCI) system. Determining what contributes to family caregiver satisfaction is a critical step toward implementing effective quality improvement strategies. A national cross-sectional descriptive survey was conducted from November to December 2008, using proportionate quota sampling based on the location and level of Long-Term Care of the beneficiaries. Total 1,745 family caregivers wrote informed consents and 733 (response rate 42%) completed questionnaires, which included caregiver characteristics, organizational resources, primary objective and subjective stressors, perceived quality of services, and family caregiver satisfaction. Family caregivers were satisfied overall with institutional care. In multiple regression analysis, there was a statistically significant difference in degree of family caregiver satisfaction according to caregiver characteristics(relationship to beneficiary), primary objective stressors (insurance type of beneficiary), perceived quality of services(respect to family caregivers' idea, ADL support, expertness of staff, careful concern of staff, fulfillment of client's requests, and safety of institution's environment). In public long-term care, satisfaction efforts are in an early stage of development. This study is meaningful as the first attempt to measure family caregiver satisfaction with institutional care for beneficiaries under the PLTCI system, and to identify factors affecting the satisfaction. Among the identified factors, the policy makers, the insurer, and the providers need to pay attention to perceived quality of services, in particular, to improve customer satisfaction. Our findings can provide quality care improvement initiatives in the public long-term care setting.

• Archives of Plastic Surgery
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• 제41권5호
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• pp.550-555
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• 2014

Background Nipple reconstruction following breast mound reconstruction is the final step in breast reconstruction. Although nipple reconstruction is a simple surgery, the psychological aspects of nipple reconstruction are thought to be important. Nipple projection is a key factor in determining patient satisfaction with the surgery. In the present study, the Hammond flap technique was introduced for nipple reconstruction. Methods Twenty-six patients who had undergone breast reconstruction from February 2008 to March 2012 were enrolled in this prospective study. All patients were evaluated based on preoperative photos, and their nipple diameters and heights were measured. Postoperative evaluation was conducted 3, 6, 9, and 12 months following nipple reconstruction. A questionnaire on patient satisfaction with the nipple reconstruction was administered 12 months after nipple reconstruction. Moreover, the same plastic surgeon scored nipple projection and overall cosmetic result of the new nipple. Results The mean projection was 4.4 mm (range, 3-6 mm), and it well matched the contralateral nipple. Twelve months following nipple reconstruction, the mean reduction rate in the nipple projection was 43.6%. Patients were satisfied or very satisfied with the nipple projection and the overall cosmetic result in 80.7% cases. Conclusions In the present study, compared with other techniques, the use of the Hammond flap technique in nipple reconstruction showed competitive results with regard to nipple projection and patient satisfaction.

• 대한화학회지
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• 제33권5호
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• pp.468-476
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• 1989

여러가지 피리딘 존재하에서 1-염화안트라센술포닐(1-ASC) 및 3-페난트렌술포닐(3-PSC)이 메탄올 속에서 각각 일으키는 반응의 메카니즘을 속도론적으로 논의하였다. 이들 반응에 대한 Bronsted계수(${\beta}$)는 $20^{\circ}C$에서 1-ASC : 0.55, 3-PSC : 0.43였고 Hammett 반응상수(${\rho}$ 온도에서 1-ASC : -3.5, 3-PSC : -2.6이었다. 두 반응계에 대한 반응성-선택성 원리를 검토한 결과, 등선택성 온도는 $34.3^{\circ}C$였으며 이보다 높은 온도에서는 이 원리가 성립하지 않음을 알았다. 활성화 파라미터와 함께 위의 결과로부터 이들 반응은 속도 결정단계에서 synchronous $S_n2$메카니즘에 의해 진행되는 것으로 결론 지어졌다.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.93-97
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• 2014

A kinetic study is reported on nucleophilic substitution reactions of 4-nitrophenyl X-substituted-2-methylbenzoates (5a-e) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. The Hammett plots for the aminolysis of 5a-e are nonlinear, e.g., substrates possessing an electron-donating group (EDG) in the benzoyl moiety deviate negatively from the linear line composed of substrates bearing no EDG. In contrast, the Yukawa-Tsuno plots for the same reactions exhibit excellent linear correlations with ${\rho}_X$ = 0.30-0.59 and r = 0.90-1.15, indicating that the nonlinear Hammett plots are caused by stabilization of the substrates possessing an EDG through resonance interactions but are not due to a change in the rate-determining step (RDS). The Br${\phi}$nsted-type plots are linear with ${\beta}_{nuc}$ = 0.66-0.82. Thus, the aminolysis of 5a-e has been suggested to proceed through a stepwise mechanism in which departure of the leaving group occurs at the RDS. The ${\rho}_X$ and ${\beta}_{nuc}$ values for the aminolysis of 5a-e increase as the reactivity of the substrates and amines increases, indicating that the reactivity-selectivity principle is not applicable to the current reactions.

• Bulletin of the Korean Chemical Society
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• 제29권7호
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• pp.1335-1343
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• 2008

Theoretical studies on the un-catalyzed and catalyzed aminations of ketene with $NH_3$ and $(NH_3)_2$, respectively, were studied using MP2 and hybrid density functional theory of B3LYP at the 6-31+G(d,p) and 6- 311+G(3df,2p) basis sets in the gas phase and in benzene and acetonitrile solvents. In the gas phase reaction, the un-catalyzed mechanism was the same as those previously reported by others. The catalyzed mechanism, however, was more complicated than expected requiring three transition states for the complete description of the C=O addition pathways. In the un-catalyzed amination, rate determining step was the breakdown of enol amide but in the catalyzed reaction, it was changed to the formation of enol amide, which was contradictory to the previous findings. Starting from the gas-phase structures, all structures were re-optimized using the CPCM method in solvent medium. In a high dielectric medium, acetonitrile, a zwitterions formed from the reaction of $CH_2$=C=O with $(NH_3)_2$, I(d), exists as a genuine minimum but other zwitterions, I(m) in acetonitrile and I(d) in benzene become unstable when ZPE corrected energies are used. Structural and energetic changes induced by solvation were considered in detail. Lowering of the activation energy by introducing additional $NH_3$ molecule amounted to ca. −20 $\sim$ −25 kcal/mol, which made catalyzed reaction more facile than un-catalyzed one.

• Bulletin of the Korean Chemical Society
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• 제34권4호
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• pp.1115-1119
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• 2013

A kinetic study is reported for nucleophilic substitution reactions of benzyl 2-pyridyl thionocarbonate (5b) and t-butyl 2-pyridyl thionocarbonate (6b) with a series of alicyclic secondary amines in $H_2O$ at $25.0^{\circ}C$. General-base catalysis, which has often been reported to occur for aminolysis of esters possessing a C=S electrophilic center, is absent for the reactions of 5b and 6b. The Br${\o}$nsted-type plots for the reactions of 5b and 6b are linear with ${\beta}_{nuc}$ = 0.29 and 0.43, respectively, indicating that the reactions of 5b proceed through a stepwise mechanism with formation of a zwitterionic tetrahedral intermediate ($T^{\pm}$) being the rate-determining step while those of 6b proceed through a concerted mechanism. The reactivity of 5b and 6b is similar to that of their oxygen analogues (i.e., benzyl 2-pyridyl carbonate 5a and t-butyl 2-pyridyl carbonate 6a, respectively), indicating that the effect of modification of the electrophilic center from C=O to C=S (i.e., from 5a to 5b and from 6a to 6b) on reactivity is insignificant. In contrast, 6b is much less reactive than 5b, indicating that the replacement of the $PhCH_2$ in 5b by the t-Bu in 6b results in a significant decrease in reactivity as well as a change in the reaction mechanism (i.e., from a stepwise mechanism to a concerted pathway). It has been concluded that the contrasting reactivity and reaction mechanism for the reactions of 5b and 6b are not due to the electronic effects of $PhCH_2$ and t-Bu but are caused by the large steric hindrance exerted by the bulky t-Bu in 6b.

• 한국전자통신학회논문지
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• 제12권6호
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• pp.1159-1166
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• 2017

가속도 및 자이로 센서, 아두이노 프로 미니와 블루투스 모듈을 이용하여 사물인터넷 기반의 소 행동 특성을 관찰할 수 있는 시스템을 설계하고 구현하였다. 구현된 시스템을 통해 소의 움직임을 관찰하고 측정하였으며, 측정된 데이터를 블루투스 모듈을 통해 스마트폰으로 전송하여 스마트 폰에서 소의 움직임 변화를 그래프를 통해 나타내었으며 이를 통해 소의 걸음 수를 측정하도록 하였다. 구현된 시스템과 제안한 알고리듬에 의해 소의 발정 상태를 판단하며, 이는 소의 인공수정에 의한 번식력 향상에 도움을 줄 수 있다. 본 논문에서 구현된 시스템을 실제 소의 다리에 부착하여 데이터를 측정하고, 제안한 알고리듬에 의해 발정 유무를 판단하였다. 향후 연구 과제로 피 측정되는 소의 개체수와 통신 거리를 늘려 축산 농가에서 좀 더 효율적으로 사용할 수 있는 시스템 연구 및 측정 데이터의 데이터베이스화를 하고자 한다.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1128-1132
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• 2014

A kinetic study on aminolysis of 4-chloro-2-nitrophenyl X-substituted-benzoates (6a-i) in MeCN is reported. The Hammett plot for the reactions of 6a-i with piperidine consists of two intersecting straight lines, while the Yukawa-Tsuno plot exhibits an excellent linear correlation with ${\rho}_X$ = 1.03 and r = 0.78. The nonlinear Hammett plot is not due to a change in rate-determining step (RDS) but is caused by the resonance stabilization of substrates possessing an electron-donating group in the benzoyl moiety. The Br${\phi}$nsted-type plot for the reactions of 4-chloro-2-nitrophenyl benzoate (6e) with a series of cyclic secondary amines is linear with ${\beta}_{nuc}$ = 0.69, an upper limit for reactions reported to proceed through a concerted mechanism. The aminolysis of 6e in aqueous medium has previously been reported to proceed through a stepwise mechanism with a change in RDS on the basis of a curved Br${\phi}$nsted-type plot. It has been concluded that instability of the zwitterionic tetrahedral intermediate ($T^{\pm}$) in MeCN forces the reaction to proceed through a concerted mechanism. This is further supported by the kinetic result that the amines used in this study are less reactive in MeCN than in $H_2O$, although they are more basic in MeCN over 7 $pK_a$ units.

• 공업화학
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• 제3권3호
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• pp.507-515
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• 1992

본 연구에서는 소성 dolomite와 수증기계의 열화학 반응을 축열식열교환기에 응용하기 위해 충전층 형태의 실험장치에서 축열 및 방열특성에 관한 연구를 수행하였다. 실험 data는 수화반응온도 $150-400^{\circ}C$, 탈수반응온도 $700-800^{\circ}C$ 및 수증기 유량 294, 430, 567 g/hr의 실험조건에서 얻은 결과이다. 본 연구의 실험범위내에서는 소성 dolomite중 MgO가 수화반응 과정중 수화되지 않음을 알았다. 따라서 소성된 dolomite중 MgO는 불활성 물질로 취급할 수 있다. 또한 율속단계는 충전층의 입구와 벽면으로부터, 출구와 중심쪽으로 반응이 진행되므로 반응율속보다는 열전달율속으로 진행된다고 생각된다.