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Two Dimensional Transfer Modes in $CH_2$ Spin System
NamGoong Hyun Korean Magnetic Resonance Society 2006 Journal of the Korean Magnetic Resonance Society Vol.10 No.1
Spin-lattice relaxation pathway of $CH_2$ spin system by two dimensional NOESY sequence has been discussed. Two-dimensional spectra governed by dipolar relaxation mechanism were simulated in term of transfer mode, the generalization of conventionally used magnetization mode in one dimension. The transfer matrix directly related to the Redfield relaxation matrix can be constructed by the multiplet of transfer mode. The observable relaxation transfer modes causes to variation of the off-diagonal signal intensity of phase sensitive NOESY spectra from which variable spectral density can be extracted with simple group theoretical calculation. The variation of the J-coupling peak intensity as a function of the mixing time in 2-D spectra for $n-Undecane-5-^{13}C$ and Bromoacetic $2-^{13}C$ acid has been theoretically traced.
Hyun Namgoong,Jo Woong Lee Korean Chemical Society 1993 Bulletin of the Korean Chemical Society Vol.14 No.1
In this work we have studied the spin-lattice relaxation of $^{19}$F spins in benzotrifluoride in our quest for a reliable method of discriminating the contribution due to dipolar relaxation mechanism from that due to spin-rotational mechanism for nuclear spins located on methyl or substituted methyl group in organic molecules. Over the temperature range of 248-268 K the decay of normalized longitudinal magnetization was found to be well described by a two parameter equation of the form R(t) = exp(-st){$\frac{5}{6}$exp(-s$_1$)+$\frac{1}{6}$} which was derived under the assumption that interactions in the A3 spin system are modulated randomly and predominantly by internal rotational motions of -CF_3$ top, and it was shown that the separation of contribution due to dipolar interactions from that due to spin-rotation interaction could be successfully achieved by least-square fitting of observed data to this equation. The results indicate that the spin-rotational contribution is overwhelmingly larger than that of dipolar origin over the given temperature range and becomes more deminating at higher temperature.
Micro-Chemical Structure of Polyaniline Synthesized by Self-Stabilized Dispersion Polymerization
NamGoong, Hyun,Woo, Dong-Jin,Lee, Suck-Hyun The Polymer Society of Korea 2007 Macromolecular Research Vol.15 No.7
A variety of NMR techniques were applied to the micro-chemical structural characterization of polyanilines prepared via an efficient synthetic method in a self-stabilized dispersion medium in which the polymerization was conducted in a heterogeneous organic/aqueous biphasic system without any stabilizers. Here, the monomer and growing polymer chain were shown to function simultaneously as a stabilizer, imparting compatibility for the dispersion of the organic phase, and as a form of flexible template in an aqueous reaction medium. Polymerizations predicated on this concept generated polyanilines with a low defect content: solution state $^{13}C-NMR$ and solid $^{13}CDD/CP/MAS$ spectroscopy indicated that the synthesized HCPANi and its soluble derivative, HCPANi-t-BOC, evidenced distinctly different NMR spectra with fewer side peaks, as compared to conventionally prepared PANis, and the complete structural assignments of the observed NMR peaks could be determined via the combination of both 1D and 2D techniques. Ortho-linked defects in HCPANi were estimated to be as low as 7%, as shown by a comparison of the integration of the carbonyl carbon resonance peaks.
( Hyun Namgoong ),( Chaeeun Cho ),( Sewon Lee ) 한국운동영양학회 2018 Physical Activity and Nutrition (Phys Act Nutr) Vol.22 No.3
[Purpose] Previous studies have indicated that Kv7 channels have an important role in the regulation of blood vessel reactivity, including in the coronary, renal, and cerebral arteries. The present studies examined whether Kv7 channels regulated vascular reactivity in the mouse aorta and investigated the mechanisms involved in the reactivity. [Methods] Wild-type (WT) male C57BL/6 mice, between 10 and 15 weeks old, were used in this study. The vascular function of the aorta in WT male mice was assessed by using a pin myography system (Model 620; DMT, Denmark). [Results] Vasorelaxation by an endothelial-dependent vasodilator, acetylcholine (ACh, 1 nM - 10 μM) and an endothelial-independent vasodilator, sodium nitroprusside (SNP, 1 nM - 10 μM) was induced in the aorta in a dose-dependent manner. Pre-incubation with the nitric oxide synthase inhibitor, L-NAME (100 μM, 20 min), completely abolished ACh-induced vasorelaxation, but did not block retigabine-induced vasorelaxation, which suggested that retigabine caused vasorelaxation in the aorta via smooth muscle activation rather than via endothelial cells. Pre-application of the Kv7 channel blocker, linopirdine (10 μM), resulted in a greater contractile response compared with that induced by vehicle in the aorta. In addition, pre-incubation with linopirdine (10 μM, 20 min) reduced retigabine-induced vasorelaxation (1-50 μM). [Conclusion] This study has provided evidence that Kv7 channels may play a role in the regulation of aortic blood flow via smooth muscle activation.
온라인 포탈 서비스를 활용한 사용자 관심사의 의미적 확장 방법
남궁현(Hyun Namgoong),정진욱(Jinuk Jung),이강용(Kang Yong Lee),조기성(Kee Seong Cho),김홍기(Hong-Gee Kim) 한국HCI학회 2012 한국HCI학회 학술대회 Vol.2012 No.1
본 논문은 개인화된 추천을 위해 소셜 네트워크 서비스(Social Network Service) 로부터 얻은 사용자 관심사 단어들로부터 추천 서비스에서 활용 용이한 일반화된 형태의 키워드들을 이끌어 내기 위한 의미적 확장 방법을 제안한다. 의미적 확장은 사용자 관심사 단어들을 유사한 단어들로 확장하는 단어 확장과 이렇게 확장된 단어의 집합에 대한 대표성을 가지는 단어를 선택하는 대표화 방법으로 이루어진다. 논문에서 제안된 의미적 확장은 방법은 SNS 에서 얻은 사용자의 관심사를 보다 일반화된 형태의 문맥정보를 제공하여, 최근 주목을 받고 있는 여러 형태의 개인화 서비스에서의 사용자 관심사의 활용을 용이하게 해줄 것으로 기대한다. This paper proposes an approach to expand user interest words gathered from social network services to keywords to be easily usable at personalized content recommendation systems. The proposed approach, named semantic expansion, is consisted of word expansion and delegation. Former discovers relative words with given user interest words whereas later selects representative words among them. We expect the proposed approach will enhance the personalized services by providing contextual information on user interests.