작은 분자의 다양한 필터를 통한 이론적 이완작용

남궁현 空軍士官學校 1994 論文集 Vol.34 No.-

분자운동을 연구하는데 cross-correlation spectral density를 얻어내는 것은 매우 중요한 일이다. Methyl Group과 같은 A_3 스핀계에서도 이 효과에 의해 multiple Quantum filtering을 통해서도 peak가 나타나게 된다. 이번 연구에서는 잘 알려진 작은 분자의 spectral density를 이용하여 double quantum과 zero quantum filtering을 하였을때 peak가 excitation과 acquisition 시간에 따라 어떻게 변화되는지를 이론적으로 살펴 보았다.

한국 뿌리차의 生藥學的 硏究

남궁현,이영민,정숙경,신은정,김지영,박숙희 이화여자대학교약학회 1990 梨花藥學硏究 Vol.- No.29

Mixture and Quantitative Analysis by NMR Spectroscopy

남궁현 한국고분자학회 2011 한국고분자학회 학술대회 연구논문 초록집 Vol.2011 No.2

Two Dimensional Transfer Modes in CH2 Spin System

남궁현 한국자기공명학회 2006 Journal of the Korean Magnetic Resonance Society Vol.10 No.1

Spin-lattice relaxation pathway of CH2 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-5-13C and Bromoacetic 2-13C acid has been theoretically traced 영어논문

Characterization of Internal Reorientation of Methyl Group in 2,6-Dichlorotoluene

남궁현,노정래 한국자기공명학회 2009 Journal of the Korean Magnetic Resonance Society Vol.13 No.1

The two correlation times previously obtained in our coupled 13C relaxation measurement for the methyl group in 2,6-dichlorotoluene may be used as a criterion for evaluating the reorientation dynamics of an internal rotor. We numerically tested an extended diffusion model and the Smoluchowski diffusion equation to see how the rotational inertial effect and jump character contribute to the internal correlation time ratio of the internal rotor. We also analytically solved the general jump model with three different rate constants in a sixfold symmetric potential barrier. By assuming that the internal rotation of the methyl group in 2,6-dichlorotoluene can be described in terms of jumps among sixfold harmonic potential wells, we can conclude that the jump model satisfactorily reproduce the experimental data and the rate for sixfold jump is at least 1.53 times as great as that of a threefold jump.

Efficient baseline suppression via TIP and modified DEPTH

남궁현 한국자기공명학회 2022 Journal of the Korean Magnetic Resonance Society Vol.26 No.4

The baseline flattened NMR spectrum has been achieved by several methodologies including pulse manipulation with a series of phase cycling. The background signal inherent in the probe is also main source of baseline distortion both in solution and solid NMR. The simple direct polarization with 90o pulse flipping the magnetization from the z-axis onto the receiver coil requires the strong rf pulse enough to encompass the wide frequency range to excite the resonance of interest nuclei. Albeit the perfect polarization 90o pulse, the signal from the unwanted magnetic fields such as background signal can not be completely suppressed by suitable phase cycling. Moreover, slowly baseline wiggling signal from the low gamma nuclei is not easy to eliminate with multiple pulse manipulation. So there is still need to contrive the new scheme for that purpose in an adroit manner. In this article new triple pulse excitation schemes for TIP and modified DEPTH pulse sequence are analytically examined in terms of arbitrary phase and flip angle of pulse. The suitable phase cycling for these pulse trains is necessary for the good sensitivity and resolution of the spectrum. It is observed that the 13C sensitivity TIP experiment is almost equal to the CP/MAS with modified DEPTH sequence, both of which are applicable to both solid and solution state NMR.

Study on Direct Dipolar Effect of Neighboring Protons in Proton Coupled $^{13}C$ Relaxation Experiment

남궁현,이임표,이조웅,NamGung, Hyeon,Lee, Im Pyo,Lee, Jo Ung Korean Chemical Society 2000 Bulletin of the Korean Chemical Society Vol.21 No.11

The dipolar effect of neighboring protons that are not directly bonded to the carbon of interest on coupled carbon-13 relaxation in a simple organic molecule has been studied by comparing the relaxation behaviors of labeled carbon-13 in $Br13CH_2COOH$ with those in $BrCH_213COOH.$ Various pulse sequences, such as coupled inversion recovery pulse sequence, J-negative and J-positive pulse sequence, and nonselective and selective proton ${\pi}pulse$ sequence, were employed to perform the required coupled spin relaxation experiments. To gain information on various spectral densities, including that of dipolar-CSA cross correlation, the experiments were performed on two different spectrometers, operating, respectively, at 50.31 and 125.51MHz for 13C. The magnitude of CH dipolar spectral densities for $BrCH_213COOH$ was found to be about 8% of those for $Br13CH_2COOH$, which means the effect due to the protons not directly bonded to the carbon of interest is small but not completely negligible.

Micro-Chemical Structure of Polyaniline Synthesized by Self-Stabilized Dispersion Polymerization

남궁현,우동진,이석현 한국고분자학회 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 13C-NMR and solid 13C DD/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.

A Study on Local Segmental Motions of Methylene Chain in Poly(Butylene Terephthalate) in Solution Phase

남궁현,오정래,이조웅,NamGung, Hyeon,O, Jeong Rae,Lee, Jo Ung Korean Chemical Society 2000 Bulletin of the Korean Chemical Society Vol.21 No.11

Temperature dependent data of 13C spin-lattice relaxation times and NOE factors for methylene carbons at 50.3MHz and 125.5 MHz have been used to probe the local chain dynamics of poly(butylene terephthalate) (PBT) in solution phase. The interpretation of the relaxation data for methylene chain carbons in PBT was attempted on the basis of several proposed motional models, among which the DLM model was found to be superior. Analysis based on the DLM model indicated that the motion of the $OCH_2groups$ was more restricted compared with the central methylene carbon, which is consistent with conclusions from solid state experiments reported by other investigators. Librational amplitudes of terminal and central carbon of PBT were estimated to be $29.84^{\circ}$ and $32.01^{\circ}respectively.

경주읍성 수습 탑신석 부조상에 관한 고찰

남궁현 회당학회 2006 회당학보 Vol.11 No.-

According to documentary records in China and Japan, Esoteric Buddhism monks in Silla after Myeongnang(明朗) and Hyetong(惠通) went to China, learned Buddhism there from SunmuisamJang(善無畏), GeumgangjisamJang(金剛智), BulgongsamJang(不空) and other Chinese monks and came back to Silla. Since further information than these documents is needed to fully study Esoteric Buddhism monks, research was done on the formative arts. Our research re-sult tells us that the most of Vairocana holds their hands in the bodhi??ri mudr?(智拳印) on Chilsajajwa(七獅子座), suggesting corre-spondence between the bodhi?sattva form in the bodhi??ri mudr? of Vajradh?tu (金剛界大日如來) and iconography. Iconography of Ekadasamukha(十一面觀音菩薩像) and Ten ThouSands Armed Bodhi?sattva(千手觀音菩薩像), both established with Sinjudokseong (神呪讀誦, an evil?repelling incantation) were introduced into United Silla at the end of 7th Century and were made during the 8th and 9th Century. Among embossed work on stone pagodas, images of the Four Guardian Kings(四天王像) and twelve zodiac figures(十二支像) are expected to be closely related with Myeongnang’s(明朗) Sininjong(神印宗). And other Sinjangsang(神將像) was also expectedly built to preserve relics of the Buddha and to protect a nation. In particular, Sinjangsang embossed on a base rock of stone pagoda in Gyeongju Fortress(慶州邑城) was ana-lyzed and found to be Myeongwang Sang(明王像, vidy?[dhara]r?ja, suggesting that Sinjangsang appeared after other previously em-bossed work on stone pagodas in the site of Sach’?nwangsa Temple(四天王寺) and Wonwon Temple(遠願寺) might be affected by Esoteric Buddhism.