• Journal of Ginseng Research
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• 제22권2호
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• pp.96-101
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• 1998

This paper describes the determination of bulk density and the discrimination of internal structure of red ginseng by nuclear magnetic resonance (NMR). The 102 red ginseng roots were tested for bulk density. The NMR properties measured by NMR parameters such as spin-lattice relaxation time ($T_1$) and spin-spin relaxation time ($T_2$) were determined using the low field proton NMR analyzer. Bulk density of red ginseng root showed a highly negative significant correlation (r=-0.8934) with the value of $T_1$, but a highly positive significant correlation (r=0.7672 and 0.5909) with the value of T21 (short T2) and T22 (long T2), respectively. Multiple regression equation, Y=-0.0069.$T_1$+0.3044.$T_{21}$-0.0156.$T_{22}$-0.6368, using the MNR parameter values of 80 red ginseng roots can effectively predict the bulk density of 22 red ginseng roots with the correlation coefficient of 0.9396 and the standard error of 0.086. The differences in the internal structure of normal and inside white part of red ginseng were easily found by the signal intensity of NMR image based on magnetic properties of proton nucleus.

• 대한의용생체공학회:의공학회지
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• 제36권6호
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• pp.241-250
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• 2015

Noninvasive temperature monitoring is feasible with Magnetic Resonance Imaging (MRI) based on temperature sensitive MR parameters such as $T_1$ and $T_2$ relaxation times, Proton Resonance Frequency shift (PRFs), diffusion, exchange process, magnetization transfer contrast, chemical exchange saturation transfer, etc. While the temperature monitoring is very useful to guide the thermal treatment such as RF hyperthermia or thermal ablation, the optimization of the MR thermometry method is essential because the range of temperature measurement depends on the choice of the measurement methods. Useful temperature range depends on the purpose of treatment methods, for example, $42^{\circ}C$ to $45^{\circ}C$ for RF hyperthermia and over $50^{\circ}C$ for thermal ablation. In this paper, MR thermometry methods using $T_1$ and $T_2$ relaxation times and PRFs-based MR thermometry are tried on a 3.0 T MRI system and their results are reported and compared. In addition, the scanning protocol and temperature calculation algorithms from $T_1$ and $T_2$ relaxation times and PRFs are optimized for the different temperature ranges for the purpose of RF hyperthermia and/or thermal ablation.

• 한국음향학회지
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• 제23권7호
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• pp.497-502
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• 2004

Poly (sodium 4-styrenesulfonate) 수용액에 대한 3 MHz의 초음파 음속측정과 0.2-2.2 MHz의 범위에 대한 흡수계수를 측정하였다. 음속은 펄스법을 사용하여 농도 5-25 wt%, 온도 10-90 ℃에 대하여 측정한 결과, 농도 25, 20, 15, 10, 5 wt%에 대한음속의 최대치 온도는 각각 55, 59, 63, 67, 71 ℃이였다. 흡수계수측정은 광 회절 초음파공명법을 사용하여 농도 5-25 wt%, 20 ℃에서 행하였다. 그 결과, 200 kHz부근에서 고분자 chain의 부분운동에 의한 완화현상을, 1 MHz 부근에서는 술폰기 (SO₃)의 proton의 전이에 의한 완화현상을 각각 관측하였다. 흡수계수와 점성은 농도와 함께 증가하였으나 온도증가에 대해서는 감소하였다.

• Bulletin of the Korean Chemical Society
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• 제23권12호
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• pp.1811-1815
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• 2002

We have calculated energies and structures for the hydrogen bonded clusters between trimethyl phosphate and nitric acids. The hydrogen bond lengths between phosphoryl oxygen and the proton of nitric acid are short compared to normal hydrogen bonds, and the H-bond strengths are fairly strong. The hydrogen bond length becomes longer, and the strength becomes weaker, as more nitric acids are bound to the TMP. The average H-bond strengths for the $TMP-(HNO_3)_n$ complexes with n = 1, 2, and 3, are 9.6, 7.9 and 6.4kcal/mol at 300K respectively. Weak hydrogen bonds between nitrate oxygen and methyl proton might contribute to the stability of the clusters. Not only the BSSE but also the fragment relaxation energies should be considered to calculate hydrogen bond strengths for the complexes accurately.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2909-2917
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• 2021

Following the launch of Rare Isotope Science Project in December 2011, a heavy ion accelerator complex in South Korea, named RAON, has since been designed. It includes a muon facility for muon spin rotation, relaxation, and resonance. The facility will be provided with 600 MeV and 100 kW (one-fourth of the maximum power) proton beam. In this study, the graphite target in RAON was designed to have a rotating disk shape and was cooled by radiative heat transfer. This cool-down process has the following advantages: a low-temperature gradient in the target and the absence of a liquid coolant cooling system. Monte Carlo simulations and ANSYS calculations were performed to optimize the target system in a thermally stable condition when the 100 kW proton beam collided with the target. A comparison between the simulation and experimental data was also included in the design process to obtain reliable results. The final design of the target system will be completed within 2020, and its manufacturing is in progress. The manufactured target system will be installed at the RAON in the Sindong area near Daejeon-city in 2021 to carry out verification experiments.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.128-135
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• 1998

The paper gives a brief introduction to protonic defects and their chemistry, thermodynamics and transport in oxides. The temperature dependence of the equilibrium concentration of protons is illustrated and compared for different acceptor-doped oxides. The difficulties of saturating as well as emptying the oxides of protons are discussed. In order to illustrate the possibility of lattice relaxation of defects, a conceptual study is made of a case where the enthalpy of dissolution of protons(water) at the cost of oxygen vacancies is assumed dependent on the concentration of vacancies. It is shown how this changes the behavior of hydration curves vs temperature and water vapour pressure. finally, a discussion is given on the water uptake in heavily oxygen deficient oxides; how water uptake may affect order-disorder in the oxygen sublattice and eventually lead to defective, disordered or ordered oxyhydroxides or hydroxides of potential interest as intermediate temperature proton conductions.

• 대한화학회지
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• 제19권3호
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• pp.149-155
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• 1975

플라스틱 결정체인 피발산의 temperature-dependent wide-line NMR line width, second monent 및 spin-lattice relaxation times 의 결과는 이 결정체의 특이한 운동학적 성질 및 수소결합에 기인된 것으로 해석된다. 이 분자의 운동학적 성질은 $C_3-C_3'$ reorientation 및 self-diffusion 으로 구성 되었음을 확인했다. Wide-line NMR 연구결과는 또한 Pople-Karasz 융해설과 비교검토되었고, 이 이론과의 차이점은 피발산의 수소결합에 기인되었음을 알아냈다.

• Bulletin of the Korean Chemical Society
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• 제15권7호
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• pp.553-559
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• 1994

Dynamics of $CH_2CI$ group in ${\alpha},2,6$-trichlorotoluene dissolved in $CDCl_3$ was studied by observing various relaxation modes for $^{13}C$ under proton undecoupled condition. Partially relaxed $^{13}C$ spectra were obtained at $34^{\circ}C$ as a function of evolution time after applying various designed pulse sequences to this $AX_2$ spin system. It was found that nonlinear regression analysis of the relaxation data for these magnetization modes could provide the information about dipolar and spin-rotational auto-correlation and cross-correlation spectral densities for fluctuation of the $^{13}C-^1H$ internuclear vector in $CH_2Cl$ group. The results show that the effect of cross-correlation is comparable in magnitude to that of auto-correlation and the relaxation in this spin system is dominated by dipolar mechanism rather than spin-rotational one. From the resulting spectral density data we could calculate the bond angle ${\angle}HCH\;(105.1$^{\circ}$) and elements of the rotational diffusion tensor for $CH_2Cl$ group.

• Bulletin of the Korean Chemical Society
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• 제13권3호
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• pp.296-306
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• 1992

$^{13}C$ spin-lattice relaxation times were measured for n-alkanes of moderate chain length, ranging from n-octane to n-dodecane, under the condition of proton broad-band decoupling within the temperature range of 248-318 K in order to gain some insight into basic features of segmental motions occurring in long chain ploymeric molecules. The NOE data showed that except for methyl carbon-13 dipole-dipole interactions between $^{13}C$ and directly bonded $^1H$ provide the major relaxation pathway, and we have analyzed the observed $T_1data$ on the basis of the internal rotational diffusion theory by Wallach and the conformational jump theory by London and Avitabile. The results show that the internal rotational diffusion constants about C-C bonds in the alkane backbone are all within the range of $10^9\;-10^10\;sec^{-1}$ in magnitude while the mean lifetimes for rotational isomers are all of the order of $10^{-11}\;-10^{-10}$ sec. Analysis by the L-A theory predicts that activation energies for conformational interconversion between gauche and trans form gradually increase as we move from the chain end toward the central C-C bond and they are within the range of 2-4 kcal/mol for all the compounds investigated.

• Food Science and Biotechnology
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• 제17권1호
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• pp.102-105
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• 2008

The freezing patterns of commercial frozen foods were characterized by using proton nuclear magnetic resonance ($^1H$ NMR) relaxometry and differential scanning calorimetry (DSC). The liquid-like components like unfrozen water were investigated as a function of temperature (10 to $-40^{\circ}C$) and then compared with the unfrozen water content measured by DSC. The formation of ice crystals and the reduction of water in the foods during freezing were readily observed as a loss of the NMR signal intensity. The proton NMR relaxation measurement showed that the decreasing pattern of the liquid-like components varied depending on the samples even though they exhibited the same onset temperature of ice formation at around $0^{\circ}C$. When compared with the unfrozen water content obtained by the DSC, the NMR and DSC results could be closely correlated at the temperature above $-20^{\circ}C$. However, the distinct divergence in the values between 2 methods was observed with further decreasing temperatures probably due to the solid glass formation which was not detected by DSC.