• 동의생리병리학회지
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• 제23권2호
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• pp.389-396
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• 2009

The ethanol extract of Persicaria perfoliata (EPP) induced relaxation of the phenylephrine-precontracted aorta in a dose-dependent manner, which was abolished by removal of functional endothelium. Pretreatment of the aortic tissues with NG-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4}-oxadiazole-[4,3-${\alpha}$)-quinixalin-1-one (ODQ) inhibited the relaxation induced by EPP. However, EPP-induced relaxation was not blocked by pretreatment with indomethacine, glibenclamide, tetraethylammonium (TEA), atropine, or propranolol. Incubation of endothelium-intact thoracic aortic ring with EPP increased the production of cGMP, which was also blocked by pretreatment with L-NAME or ODQ. These results suggest that EPP dilates vascular smooth muscle via endothelium-dependent NO/cGMP signaling.

• The Journal of the Acoustical Society of Korea
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• 제16권1E호
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• pp.24-28
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• 1997

Ultrasonic relaxation measurements for imidazole and its derivative in phosphate buffer exhibit a high peak of absorption at neutral pH. Near neutral pH, protolysis and hydrosis may be neglected and the essential reaction only consists of a direct proton-exchange. The kinetics constants and the volume changes for the proton transfer reaction with the protonated imidazole and 2-methylimidazole have been determined at 25℃. The kinetics constants are 7.2×108s-1M-1for imidazole and 1.7×108s-1M-1 for 2-methylimidazole. The kinetics constants are used to estimate the spectrum of relaxation times and acoustic relaxation amplitude associated with intermolecular and intramolecular proton-exchange reactions in bilogical media. It is concluded that the magnitude of the acoustic absorption reasonalbly attributable to the perturbation of proton-transfer equilibria between imidazole and inorganic phosphate is comparable in magnitude with the acoustic absorption observed in some intact tissues.

• 한국자기공명학회논문지
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• 제23권2호
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• pp.40-45
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• 2019

The phase transition temperatures and thermodynamic properties of $(NH_4)_2MnCl_4{\cdot}2H_2O$ grown by the slow evaporation method were studied using differential scanning calorimetry and thermogravimetric analysis. A structural phase transition occurred at temperature $T_{C1}$ (=264 K), whereas the changes at $T_{C2}$ (=460 K) and $T_{C3}$ (=475 K) seemed to be chemical changes caused by thermal decomposition. In addition, the chemical shift and the spin-lattice relaxation time $T_{1{\rho}}$ were investigated using $^1H$ magic-angle spinning nuclear magnetic resonance (MAS NMR), in order to understand the role of $NH_4{^+}$ and $H_2O$. The rise in $T_{1{\rho}}$ with temperature was related to variations in the symmetry of the surrounding $H_2O$ and $NH_4{^+}$.

• 한국자기공명학회논문지
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• 제14권2호
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• pp.76-87
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• 2010

The structural phase transition of $Cs_2MnCl_4{\cdot}2H_2O$ single crystals was investigated by determining the $^{133}Cs$ spin-lattice relaxation time $T_1$. The number of resonance lines in the $^{133}Cs$ spectrum changes from seven to one near 375 K, which means that above 375 K the Cs sites are symmetric. Further, the $T_1$ of the $^{133}Cs$ nucleus undergoes a significant change near 375 K, which coincides with the change in the splitting of the $^{133}Cs$ resonance lines. The change in $T_1$ near $T_C$ is related to the loss of $H_2O$, and means that the forms of the octahedra of water molecules surrounding $Cs^+$ are disrupted.

• Journal of Biosystems Engineering
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• 제18권3호
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• pp.262-269
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• 1993

Stress relaxation behaviors of the cucumber under bending moment were tested with UTM at three levels of loading rate and initial deflection ratio. Sample cucumber was selected from three cultivars of cucumber, Cheongjangmadi, Baekdadagi, and Gyeousalicheongjang, because these cultivars are the most popular grown cultivars in Korea. When the bending moment was applied to the cucumber sample, the effective span between simple supports was held a constant value of 116mm with consideration of the selected sample length. The objectives of this study were to develop the rheological models such as linear and nonlinear models of the stress relaxation for the cucumber samples, and to investigate the effects of loading rate and initial deflection ratio on the stress relaxation behavior of the cucumber. The results of this study may be summarized as follows : 1. Stress relaxation behavior of the cucumber could be well described by the generalized Maxwell model for each level of deflection ratio. But the stress relaxation behavior of the sample was found to be initial deflection ratio and time dependent, and it was represented the nonlinear viscoelastic model as a function of initial deflection ratio and time. 2. Stress relaxation behavior of the cucumber samples was very highly affected by the loading rate and the initial deflection ratio. The more loading rate and initial deflection ratio resulted in the more initial bending stress and after stress relaxation progressed more rapidly. 3. At the same test conditions, it was found that the stress relaxation rate of Cheongjangmadi was faster than that of other cultivars.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.546-549
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• 1993

The correlation between electrical conduct ion and dielectric relaxation properties of copper ion conducting glasses is discussed. The glasses were prepared in the system $CuI-Cu_2S-Cu_2O-MoO_3$ using rapid quenching technique. These glasses have high ionic conductivities at room temperature in the range of $10^{circ}$[S/m], and the conductivities increase with increasing CuI content. The activation energies for conduction are 0.26-0.57 eV. The dielectric relaxation times are 1-10uS, and the activation energy for ion jumping are 0.18-0.41eV. It is shown that the tendency of conduction properties depending on composition of the glass is similar those of dilectric relaxation.

• 대한수의학회지
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• 제37권1호
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• pp.119-128
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• 1997

The relaxation of gastric fundus smooth muscles is the primary physiological event which induces the receptive relaxation of monogastric animals. L-arginine/Nitric oxide(L-arg/NO) system is known to mediate the inhibitory non-adrenergic non-cholinergic(NANC) neurotransmission in various tissues including gastrointestinal smooth muscles. The longitudinal smooth muscles of porcine gastric fundus showed fast relaxation during electrical field stimulation(EFS) and rebound contraction after EFS in NANC condition. So, the purpose of present study was elucidation of the neurotrasmitters related to the NANC relaxation and explanation of the relation between NANC relaxation and L-arg/NO system. The longitdinal smooth muscles of porcine gastric fundus were hung in the organ bath and under the presence of guanethidine($5{\times}10^{-5}M$), precontraction was induced by carbachol($1{\times}10^{-6}M$). The muscle responses to EFS and drugs were isomerically recorded. The rusults were summarized as follows. 1. The longtudinal muscles of porcine gastric fundus showed frequency-dependent relaxation and rebound contraction to electrical field stimulaton(1ms, 8V, 1~16Hz, 20sec, EFS). These responses were blocked by tetrodotoxin($1{\times}10^{-6}M$). 2. The relaxation and rebound contraction of the longitudinal muscles of porcine gastric fundus to EFS were inhibited by L-NAME($2{\times}10^{-5}M$). The inhibitory effect of L-NAME was antagonized by L-arginine($1{\times}10^{-3}M$), but not by D-arginine($1{\times}10^{-3}M$). 3. Exogenous NO($NaNO_2$, $1{\times}10^{-5}{\sim}1{\times}10^{-4}M$, pH=2.0) caused concentration-dependent relaxation as EFS did. 4. Methylene Blue($2{\times}10^{-5}M$), a soluble guanylate cyclase inhibitor, inhibited the relaxation and rebound contraction of the longitudinal muscles of porcine gastric fundus induced by EFS, but N-ethlmaleimide, a adenylate cyclase inhibitor, did not. 5. 8-Br-cGMP($1{\times}10^{-6}{\sim}3{\times}10^{-6}M$), permeable cGMP analogue, induced dose-dependent relaxation. but 8-Br-cAMP($1{\times}10^{-6}{\sim}3{\times}10^{-6}M$), permeable cAMP analogue, did not. Both did not evoked rebound contraction. 6. ${\alpha}$-chymotrypsin did not affect the relaxation of the longitudinal muscles of porcine gastric fundus. 7. Reactive blue 2($1{\times}10^{-4}M$, 40min) siginificantly inhibited the rebound contraction induced by EFS and inhibited contraction caused by exogenous ATP($1{\times}10^{-4}{\sim}1{\times}10^{-3}M$). These results suggests that NANC relaxation of the longitudinal muscles of porcine gastric fundus mainly mediated by NO and the rebound contraction is related to NO and other neurotransmitters.

• 한국자기공명학회논문지
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• 제15권2호
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• pp.146-156
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• 2011

The line widths and spin-lattice relaxation times of protons in $[N(C_2H_5)_4]_2CoCl_4$ and $[N(CH_3)_4]_2CoCl_4$ single crystals were investigated in the temperature range 160-400 K. The temperature dependences of the spin-lattice relaxation times are attributed to the molecular motions of the ethyl and methyl groups in the $[N(C_2H_5)_4]^+$ and $[N(CH_3)_4]^+$ ions respectively. The NMR line widths indicate that the ethyl groups in $[N(C_2H_5)_4]_2CoCl_4$ have one more degree of freedom than the methyl groups in $[N(CH_3)_4]_2CoCl_4$. The experimental results are interpreted in terms of the reorientations of the methyl and ethyl groups.

• 한국자기학회지
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• 제3권1호
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• pp.13-17
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• 1993

수소$(^{1}H)$와 불소$(^{19}F)$ 원자핵에 대한 펄스 핵자기공명 기법을 써서 $CuF_{2}.2H_{2}O$ 분말 시료를 연구하였다. 선모양과 스핀-격자 완화의 측정으로 공명 원자핵들은 격자내 상자성 이온들의 영향을 강하게 받음을 알 수 있었다. 또 이로부터 상자성 이온의 상관시간(correlation time)을 계산할 수 있었으며 관측된 공명선 폭과 스핀 메아리 붕괴상수로부터 스핀-스핀 상호작용의 크기와 공명원자핵들은 운동상태를 유추할 수 있었다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1992년도 춘계연구발표회 논문개요집
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• pp.40-41
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• 1992