Conformational Characteristics of p-tert-Butylcalix[6]arene Mono-Alkyl Ester Derivatives

정기주,유효연,석다현,장석규,안상두 한국자기공명학회 2010 Journal of the Korean Magnetic Resonance Society Vol.14 No.2

Conformational properties of several mono-alkyl ester derivatives of p-tert-butylcalix[6]arene depending on temperatures have been investigated by solution NMR spectroscopy. It is found out that all derivatives can adopt a cone-like conformation around room temperature, while the conformational characteristics at high temperatures seem to be quite different each other.

A Numerical Study on the Dynamics of Distant Dipolar Field in Solution NMR: Understanding Spatial Aspect of Magnetizations

김유라,유효연,정기추,안상두 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.10

Convection Effects on PGSE-NMR Self-Diffusion Measurements at Low Temperature: Investigation into Sources of Induced Convective Flows

정기주,유효연,안상두 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.6

The effects of convection on the measurement of the diffusion coefficients of liquids by the pulsed gradient spin echo (PGSE) NMR method at low temperature are discussed. To examine the generation of convective flows, we used four different types of sample tubes in the diffusion measurements with temperature variation;a normal 5 mm NMR tube, a Shigemi tube, an ELISE type tube, and a capillary tube. Below room temperature,the calculated diffusion coefficients of chloroform in 5 mm o.d. type tubes increased with decreasing temperature, while those in the capillary tube decreased linearly. The convective flow was found to be significant even at low temperature and it seemed to be mainly induced by the transverse temperature gradient. It was also found that the capillary tube was most appropriate to measure the diffusion coefficients, since its small diameter is effective in suppressing the convective flows at both high and low temperatures.

Composition Analysis of Grafted ABS and its Blend Copolymers Using a Combination of 1H NMR Spectroscopy and Nitrogen Element Analysis

Kim Sohyun,유효연,정찬호,최은정,Ahn Sangdoo 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.9

The composition analysis of the acrylonitrile butadiene styrene (ABS) copolymer was performed using a method combining elemental analysis and 1 H nuclear magnetic resonance (NMR) spectroscopy. The physicochemical properties of ABS are determined by the relative contents of the constituent monomers. However, because ABS undergoes a complicated microstructural change during the polymerization process, it is difficult to accurately analyze the relative contents using only a typical method. In this study, a combination of nitrogen elemental analysis and 1 H NMR spectroscopy was proposed as an analytical method that can consider the effects of changes in the microstructures. This approach confirmed whether the ABS samples were close to meeting the specifications. In addition, the composition analyses of polylactic acid/ ABS blends, polycarbonate/ABS blends, and a polyamide 6/ABS mixture sample indicate that the obtained results were consistent with the expected values, thereby demonstrating that this combined analytical approach can be applied to various types of ABS copolymer systems.

중국에서의 민사주체에 대한 법률적용

두신리(杜新麗),유효연(번역자) 한국국제사법학회 2011 國際私法硏究 Vol.- No.17

중국이 2010년에 반포한 “중화인민공화국 섭외민사관계법률적용법”(이하법률적용법)은 별도의 장(章)을 두어 민사관계주체에 관한 몇가지 사항에대하여 법률적용규칙을 규정하였다. 그 내용은 자연인의 권리능력과 행위능력, 법인의 권리능력과 행위능력, 자연인의 국적충돌과 주소충돌의 해결, 인격권, 대리, 신탁 등을 주로 포함한다. 적용규칙의 주요한 내용으로는 민사주체의 상거소지 법률이 있다. 민사주체의 법률행위 측면에서는 의사자치의 원칙을 포함하고 있으며 민사주체 자신의 의사에 대한 존중을 충분히체현하고 있다. 이전 법률에 이미 나타나 있던 것도 있고 처음으로 시도되는 규칙도 있다. 이에 따라 규칙이 다소 매끄럽지 못한 부분도 있으며 앞으로 이행과정에서 더욱 정리되고 검증되어야 한다.

Treatment Outcomes and Prognostic Factors in Children with Non-Hodgkin Lymphoma at a Single Institution

김지숙,공성김,오지은,유효연,박재선 대한소아혈액종양학회 2014 Clinical Pediatric Hematology-Oncology Vol.21 No.2

Background: Treatment outcomes of children with non-Hodgkin lymphoma (NHL) have dramatically improved in recent years. However, there are few studies on the outcomes of pediatric NHL in Korea. Methods: We retrospectively analyzed the outcomes of 34 children diagnosed with NHL and treated at Kosin University Gospel Hospital from Jan. 1987 to Dec. 2009, according to age, lactate dehydrogenase (LDH) level, histology, stage and involved site. Results: The mean age of the subjects was 9.0 years. The abdomen and head/neck regions were the most common primary sites. On histologic classification, Burkitt lymphoma was the most common, followed by lymphoblastic lymphoma, diffuse large B-cell lymphoma, anaplastic large cell lymphoma, and unclassifiable, with respective incidences of 35.3%, 23.5%, 17.6%, 17.6%, and 5.9%. Various combination chemotherapies according to the diagnosis with mean treatment duration of 14.9 months showed 5 year event free survival (EFS) and 5 year overall survival (OS) rate of 67.7±8.0% and 79.3±7.0%, respectively. Nine out of the 34 patients relapsed, and the 5 year OS rates for those who relapsed vs. 25 patients without relapse were 44.4±16.6%, vs. 92.0±5.4%, respectively (P<0.01). Although 5 year EFS rate varied according to stage, 5 year OS rate were not different according to age, sex, LDH, stage, histology, or treatment period. Conclusion: The outcome of children with NHL treated in our setting was comparable to those of other large centers in Korea. No factor other than stage, including LDH, histologic subtype showed significant prognostic value.

Experimental Analyses on Contrast Behaviors of iDQC and iTQC MR Images at 4.7 T

조지현,안상두,류은경,유효연,정기주,조장근,이철현 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.6

no abstract

중국에서의 섭외적 물권 및 지적재산권의 법률적용

두환팡(杜?芳),유효연(번역자) 한국국제사법학회 2011 國際私法硏究 Vol.- No.17

중국 신(新)국제사법의 물권 및 지적재산권 관련 규정들은 대부분 새롭게추가된 것으로, 물권법률을 적용하는 일반규정을 더욱 명확히 하는 한편 특히 동산물권, 유가증권, 권리물권, 지적재산권 등 방면의 규정도 두었다. 관련 섭외 물권 및 지적재산권의 법률선택규칙은 국내외 및 국제적 관련 입법과 최대한 일치시켰지만, 개별조항에는 아직 입법상 매끄럽지 못한 부분 및 현행 국내 실체법과 일치하지 않는 부분도 존재한다. ‘동산물권’과 ‘운송중의 동산물권’ 영역에서는 당사자가 법률을 선택하게 하는 의사자치의 원칙을 최초로 도입하였으나 과유불급이라는 느낌이 없지 않다. 중국 증권시장의 점진적인 개방을 고려하여 유가증권의 법률적용규칙을 제정하였으나 유가증권 간접보유시스템에서의 법률적용에 대한 고려는 부족하다. 지적재산권 영역의 법률충돌 가능성을 명확히 인정하였으며, ‘지적재산권의 귀속과 내용’, ‘지적재산권의 양도와 허가’, ‘지적재산권의 침해책임’ 등의 3가지 법률관계에 관한 별도의 조항을 두어 각기 다른 법률선택규칙을 규정하였다.

핵자기공명 분광법을 이용한 PC/PBT 블렌드의 에스테르 교환에 관한 반응속도 연구

이금향(Keumhyang Lee),신지영(Jiyoung Shin),유효연(Hyo-Yeon Yu),곽동환(Donghwan Kwak),김창근(Chang Keun Kim),안상두(Sangdoo Ahn) 한국고분자학회 2016 폴리머 Vol.40 No.3

¹H NMR 분석방법을 이용하여 여러가지 가열 조건하에서 폴리카보네이트/폴리(부틸렌 테레프탈레이트) (PC/PBT) 블렌드의 에스테르 교환반응 속도에 관하여 조사하였다. 일반적으로 고분자 배합비를 산출하는데 사용하는 TGA 측정 과정에서, PBT의 열분해 온도에 이르기 전에 교환반응이 매우 활발히 일어난다는 것을 확인하였으며, 이에 따라 상대적으로 높은 열분해 온도를 가지는 PC의 함량이 원래 혼합된 것보다 적은 것처럼 관측된다는 것을 알았다. 200, 250, 300℃에서 가열시간을 증가시키면서 PC/PBT(50:50 wt%) 블렌드와 분말 혼합물의 에스테르 교환반응률을 측정하였고 이를 통하여 반응속도 상수를 결정하였다. 분석한 모든 온도에서 블렌드의 반응속도 상수가 더 크게 관측되었으며, 250℃ 이상의 고온에서는 짧은 가열시간에도 교환반응이 상당히 진행된다는 것을 확인할 수 있었다. The kinetic properties of transesterification reaction in polycarbonate/poly(butylene terephthalate) (PC/PBT) blends were investigated by ¹H NMR spectroscopy under various annealing conditions. During the TGA analysis which is commonly used for composition analysis of polymer blends, the exchange reaction occurred very actively before it reached the thermal decomposition temperature of PBT. Hence, the composition of PC in thermogram seemed to be less than the original value. The kinetic constants of transesterification in PC/PBT (50:50 wt%) blend and powder mixture at 200, 250, and 300℃ were calculated from the degrees of transesterification obtained while increasing the annealing time. It was found that the kinetic constants for the blend were greater than the mixture, and the exchange reaction was considerably progressed even in the short annealing time.

선택적 용해와 수소 핵자기공명분광법을 이용한 EVA/LDPE 블렌드의 조성 분석법

신은정(Eun Jeong Shin),서예진(Yejin Seo),김석윤(Seok Yoon Kim),박도윤(Doyoon Park),정찬호(Chan Ho Jeong),유효연(Hyo-Yeon Yu),안상두(Sangdoo Ahn) 한국고분자학회 2022 폴리머 Vol.46 No.6

본 연구에서는 사이클로헥산 용매의 선택적 용해 특성을 이용하여 poly(ethylene-co-vinyl acetate)(EVA)/low-density polyethylene(LDPE) 블렌드의 배합 비율을 결정하고 ¹H NMR 분광법을 이용하여 용해된 EVA의 비닐 아세테이트(VA) 함량도 산출할 수 있는 조성 분석법을 개발하였다. 이러한 분석법을 다양한 비율로 제작된 EVA/LDPE 혼합물 및 블렌드 시료에 적용한 결과, 분리된 가용성 부분과 불용성 부분의 무게 비율이 EVA와 LDPE 배합 비율의 97-109% 수준으로 얻어졌다. 또한 가용성 부분의 VA 함량은 배합에 사용된 EVA의 VA 함량과 비교하여 혼합물 시료에서는 평균 0.6 wt%, 블렌드 시료에서는 평균 1.9 wt% 수준의 차이로 산출되었다. 이러한 결과를 통하여 선택적 용해법과 ¹H NMR 분광법을 함께 적용하는 방법이 EVA/LDPE 블렌드의 조성 분석에 적합한 것임을 확인하였다. In this study, a compositional analysis method was developed that can determine the mixing ratio of poly(ethylene-co-vinyl acetate) (EVA)/low density polyethylene (LDPE) blend using the selective dissolution properties of cyclohexane solvent and also determine the vinyl acetate (VA) content of dissolved EVA using ¹H NMR spectroscopy. As a result of applying this analysis method to EVA/LDPE mixture and blend samples prepared in various ratios, the weight ratio of the separated soluble and insoluble parts was obtained at the level of 97-109% of the EVA and LDPE mixing ratio. Compared to the VA content of EVA used for formulation, the VA content of soluble part was calculated with an average difference of 0.6 and 1.9 wt% in the mixture and blend samples, respectively. These results confirmed that the method of applying the selective dissolution and 1H NMR spectroscopy together is suitable for the composition analysis of the EVA/LDPE blend.