• 한국초전도ㆍ저온공학회논문지
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• 제18권3호
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• pp.21-24
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• 2016

Recently, production technique and property of the High-Temperature Superconductor (HTS) tape have been improved. Thus, the study on applying an HTS magnet to the high magnetic field application is rapidly increased. A Nuclear Magnetic Resonance (NMR) spectrometer requires high magnitude and homogeneous of central magnetic field. However, the HTS magnet has fabrication errors because shape of HTS is tape and HTS magnet is manufactured by winding HTS tape to the bobbin. The fabrication errors are winding error, bobbin diameter error, spacer thickness error and so on. The winding error occurs when HTS tape is departed from the arranged position on the bobbin. The bobbin diameter and spacer thickness error occur since the diameter of bobbin and spacer are inaccurate. These errors lead magnitude and homogeneity of central magnetic field to be different from its ideal design. The purpose of this paper is to investigate the effect of winding error, bobbin diameter error and spacer thickness error on the central field and field homogeneity of HTS magnet using the virtual NMR signals in MATLAB simulation.

• 한국초전도ㆍ저온공학회논문지
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• 제19권1호
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• pp.51-55
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• 2017

To obtain Nuclear Magnetic Resonance (NMR) measurement of membrane protein, an NMR magnet is required to generate high intensity, homogeneity, and stability of field. A High-Temperature Superconducting (HTS) magnet is a promising alternative to a conventional Low-Temperature Superconducting (LTS) NMR magnet for high field, current density, and stability margin. Conventionally, an HTS coil has been wound by several winding techniques such as Single-Pancake (SP), Double-Pancake (DP), and layer-wound. The DP winding technique has been frequently used for a large magnet because long HTS wire is generally difficult to manufacture, and maintenance of magnet is convenient. However, magnetic field generated by the slanted turns and the splice leads to field inhomogeneity in Diameter of Spherical Volume (DSV). The field inhomogeneity degrades performance of NMR spectrometer and thus effect of the slanted turns and the splice should be analyzed. In this paper, field gradient of HTS double-pancake coils considering the slanted turns and the splice was calculated using Biot-Savart law and numerical integration. The calculation results showed that magnetic field produced by the slanted turns and the splice caused significant inhomogeneity of field.

• 대한방사선기술학회지:방사선기술과학
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• 제44권3호
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• pp.239-245
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• 2021

Since the side effects of contrast agents occur in many ways, hospitals must clearly identify the contrast agents and know how to manage them. Storage of contrast media It is common practice to store contrast media in a warm room to reduce viscosity and improve patient comfort. However, it is important to recognize that long-term storage at high temperatures can shorten the shelf life of a product. Therefore, in this study, the presence or absence of chemical changes according to the storage period after using the contrast medium was analyzed. As the analysis equipment, a 500 MHz Nuclear Magnetic Resonance Spectrometer of Bruker Avance (Germany) possessed by Korea Basic Science Institute (KOREA BASIC SCIENCE INSTITUTE; KBSI) was used. For the X-ray iodide contrast medium, Pamiray contrast medium of Iopamidol and Optiray contrast medium of Ioversol, samples remaining after 7 days, 20 days, 30 days, and 1 year were collected, By acquiring the spectrum from the 1H-NMR spectrometer of the contrast medium stimulated by It was compared and analyzed with the standard sample. In conclusion, depending on the storage period of the contrast medium, no peaks of physical and chemical changes were observed in both the Pamiray contrast medium of Iopamidol and the Optiray contrast medium of Ioversol after 7 days, 20 days, 30 days, and 1 year after use.

• 한국자기학회지
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• 제25권6호
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• pp.185-188
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• 2015

본 연구에서는 FT-NMR 분광기를 사용하여 $NaMgCl_3$ 단결정의 구성 원자인 $^{23}Na$ 원자핵에 대한 핵 자기 공명 실험을 하였다. 이로부터 $^{23}Na$ 원자핵이 모결정 내에서 입방정계 대칭성 내에 존재한다는 것을 알았고, 200 K~410 K 온도 범위에서 $^{23}Na$ 원자핵에 대한 스핀-격자 완화 시간 $T_1$을 온도 변화에 따라 계산하였다. 온도가 증가함에 따라서 $^{23}Na$ 원자핵의 $T_1$ 값이 점차적으로 감소하였다. 스핀-격자 완화율 $1/T_1$ 이 온도 T에 선형적으로 비례하였고, $^{23}Na$ 원자핵의 스핀-격자 완화 메커니즘을 $^{23}Na$ 원자핵 스핀과 단일 포논이 직접적으로 작용하는 직접과정(direct process)으로 설명하였다. 또한 $^{23}Na$ 원자핵의 활성화 에너지를 계산하여 $E_a=4.82J/mol$를 얻었다.

• 한국자기학회지
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• 제4권2호
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• pp.184-187
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• 1994

Czochralski 방법에 의해 성장된 $CsMnCl_{3}$ 단결정에서 $^{133}Cs$의 핵자기 공명을 Bruker FT NMR 분광기를 이용하여 연구하였다. 두 개의 다른 무리의 $^{133}Cs$ 공명선이 관측되었다. : 서로 다른 intensity를 갖는 두 cesium 스펙트럼에 속하는 여러 transition이 분석되었다. Cs(I)의 핵 사중극 결합상수는 $0.15{\pm}0.01$ MHz이고, Cs(II)는 $0.21{\pm}0.01$ MHz이다. 비대칭인자는 두 경우에 대하여 영이고, 일들 두 경우의 EFG 텐서의 주축은 같았다. EFG 텐서의 가장 큰 성분을 만족하는 Z 축은 결정학적인 c축과 나란한 방향임을 알았다.

• International Journal of Industrial Entomology and Biomaterials
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• 제27권2호
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• pp.298-302
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• 2013

In this study, the effect of sericin on synthesis of the silica was investigated. Using the mixture of sericin solution and tetraethyl orthosilicate (TEOS), it was confirmed that silica could be synthesized in the presence of sericin, which was verified by thermal gravimetric analysis (TGA), Fourier-transformed infrared spectrometer (FT-IR) and nuclear magnetic resonance spectrometer (NMR) analysis. The TGA and FT-IR data revealed that silica-sericin complex was formed as a final product. Based on the TGA result, the content of silica and sericin in the complex would be 87 and 13%, respectively. The degree of silica condensation was higher than the natural biosilica. It could be concluded that sericin can induce the synthesis of silica directly from TEOS, which is similar to silicatein from marine sponges.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.64-71
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• 2003

In order to analyze the effect of the chemical structure and the cetane number of reformed diesel fuels by ultrasonic energy irradiation, proton nuclear magnetic resonance spectrometer$(^1H-NMR)$ was used. From the study, following conclusive remarks can be made. 1) Branch Index(BI), aromatics percentages, and alpha methyl radical$(H_{\alpha})$ of the reformed diesel fuels by ultrasonic energy irradiation decreased more than the conventional ones. 2) All the cetane numbers which were calculated from carbon type structure and hydrogen type distribution of the reformed diesel fuels increased more than the conventional ones. 3) It is more reasonable to predict cetane number equation from carbon type structure than from hydrogen type distribution. 4) BI, aromatics percentages, and $H_{\alpha}$ on both for conventional fuel and reformed diesel fuels by ultrasonic energy irradiation are inversely proportional to cetane number fur these fuels.

• 한국자기학회지
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• 제5권3호
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• pp.175-178
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• 1995

Czochralski 방법에 의해 성장된 $NaMnCl_{3}$ 단결정에서 $^{23}Na$의 핵자기공명의 온도 의존성이 Bruker FT NMR 분광기를 이용하여 연구하였다. $NaMnCl_{3}$에서 $^{23}Na$의 핵 사중극 결합상수는 온도가 증가함에 따라 증가하였다. 140-380 K의 온도 범위에서 $e^{2}qQ/h$의 온도 의존성은 $e^{2}qQ/h=155+0.117(T-T_{r})\;kHz$의 직선방정식으로 나타낼 수 있었다.

• Applied Biological Chemistry
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• 제32권1호
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• pp.8-13
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• 1989

자동산화반응(自動酸化反應)의 Model화합물(化合物)로서 methyl linolenate를 시간별(時間別)로 상온과 90ml/min의 air flow rate하(下)에 96시간(時間)까지 산화(酸化)시켰다. 이들 산화반응물(酸化反應物)에 대(對)한 NMR측정치(測定値)로부터 반응속도상수(反應速度常數)와 반응차수(反應次數)를 산출(算出)한 결과(結果) methyl lino1enate의 자동산화(化自動酸化)는 일차(一次) 반응속도론(反應速度論)을 따르며, 그 반응속도상수(反應速度常數)는 $1.96{\times}10^{-2}hr^{-1}$이었다. 지방산(脂肪酸)의 자동산화(自動酸化)에 대(對)한 Kinetics연구(硏究)에 여러가지 방법(方法)이 이용(利用)되고 있으나 본실험결과(本實驗結果)로 보아 NMR가 보다 신속(迅速)하고도 효과적(效果的)인 분석방법(分析方法)이라고 생각된다.

• 한국식품위생안전성학회지
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• 제12권3호
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• pp.195-199
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• 1997

For the purpose of isolation and screening of tyrosinase inhibitory activity from edible mushrooms, Pleurotus ostreatus, Auricularia auricula-Judae, Umbilicaria esculenta, Agaricus bisporus, Flammuline velutipes, Lentinus edodes, Ganoderma lucidum, and Coriouls versicolor were examined by tracing inhibitory activities against tyrosinase, utilizing L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate. Among the eight edible mushrooms tested, Umbilicaria esculenta showed potent enzyme inhibitory activities above 7804% against tyrosinase in ethylacetate (EtOAc) extracts. Ganoderma lucidum and Agaricus bisporus showed inhibitory activities of 67.3% and 51.5% in water extracts. EtOAc extracts of Umbilicaria esculenta was fractionated from silicagel column chromatography and one fraction showed the most inhibitory activity of 60.9%. The three bands (Rf=0.38, 0.27, 0.19) were isolated from preparative TLC of the fraction for purification and identified as mixtures of orsellinate, methyl orsellinate, methyl lecanorate, and methyl gyrophorate by high pressure liquid chromatography (HPLC), ultravisible spectrophotometer (UV), mass spectrophotometer (Mass), nuclear magnetic resonance spectrometer (NMR).