• Title, Summary, Keyword: Surface Coil

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3T MR Imaging에 적합한 RF Surface Coil의 개발: 피부 미세구조에 대한 예비 연구

  • 윤성익;이정우;최보영;이형구;서태석
    • Proceedings of the KSMRM Conference
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    • pp.73-73
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    • 2003
  • 목적: 피부조직과 같은 미세 인체구조 연구를 위해 고해상도 3T MRI 시스템에 적합한 고분해능의 RF surface coil을 개발하고 있다. In vivo 연구를 위한 여러 parameter를 최적화하여 기능영상에도 부합된다. 비침습적인 In vivo 검사에 의한 세포수준의 극 미세구조의 연구가 가능해짐으로써 과거 시행하던 침습적인 생검없이 각종질환의 진단적 접근이 병리학적 수준으로 향상되어 질병의 정확한 진단이 가능해지게 될 것이다.

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Numerical and experimental analysis of temperature distribution in TEFC induction motor (전폐형 유도전동기의 온도분포에 관한 수치 및 실험적 해석)

  • Yun, Myeong-Geun;Go, Sang-Geun;Han, Song-Yeop;Lee, Yang-Su
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.3
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    • pp.457-472
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    • 1997
  • We studied the temperature distribution and heat transfer characteristics of TEFC induction motor with thermal network program for more efficient design and better cooling performance of it. We knew the characteristics and the windage loss of outer cooling fan from fan test experiments. Frame axial and peripheral heat transfer coefficients and endwinding heat transfer coefficient were measured by various model experiments and then, compared with other experimental results. Frame was the main heat transfer surface, load-side and fan-side surface were not thermally symmetric from the heat flux distribution analysis. Steady and unsteady temperature distributions were measured by real motor experiments. From the results, we knew that rotor surface temperature was higher than coil temperature and the hottest spot in the coil was loadside endwinding outside surface. We compared the simulation results with those of real motor test and the two results showed a good agreement.

High-Order Surface Gradient Coil Design Using Target Field Approach

  • Lee, J.K.;Yang, Y.J.;Jeong, S.T.;Choi, H.J.;Cho, Z.H.;Oh, C.H.
    • Journal of Biomedical Engineering Research
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    • v.17 no.1
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    • pp.19-24
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    • 1996
  • The purpose of this paper is to design high-order (or radial) surface gradient coil (SGC), which can provide multi-dimensional spatial selection. Although the spatial Selection with High-Order gradienT (SHOT) can provide a 2-D selection with only one selective RF pulse, the high-order gradient pro- duced by conventional cylindrical-shape coils has not been clinically useful due to the large selection size caused by the limited radial gradient intensity. However, by using the proposed high-order SGCs located near the imaging region, the size of volume selection can be reduced to a clinically useflll size of 1-2 cm in diameter by applying stronger radial gradient field with much less gradient driving power. So far radial SGCs have been designed by using the field component method and may cause distortion in the selection shapes. In this paper, by using the target field approach for the coil design, selected volumes became almost circular. A 40 cm-by-40 cm $z^2$_surface gradient coil has been designed and implemented by using the target field approach. Phantom and volunteer studies have been performed Experimental results using spatially localized MRI show good agreement to the theoretically predicted behavior.

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Home-built Solid-state NMR Probe for Membrane Protein Studies

  • Kim, Yong-Ae;Hwang, Jung-Hyun;Park, Jae-Joon
    • Bulletin of the Korean Chemical Society
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    • v.24 no.9
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    • pp.1281-1283
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    • 2003
  • Proteins in highly oriented lipid bilayer samples are useful to study membrane protein structure determination. Planar lipid bilayers aligned and supported on glass slide were prepared. These stack of glass slide with planar lipid bilayers are not well fit for commercial solid-state NMR probe with round coil. Therefore, homebuilt solid-state NMR probe was built and used for a stack of thin glass plates and RF coil is wrapping directly around the flat square sample. The overall filling factor of the coil is much better and the large surface area enhances the extent to orientation by providing uniform environments for the phospholipids and the high ratio of circumference to area reduces edge effects. $^1H\;and\;^{15}N$ double resonance probe for 400 MHz NMR (9.4T) with a flat coil (coil size: 11 mm ${\times}$ 20 mm ${\times}$ 4 mm) is constructed and tested.

Tension/Heat/Thermal Deformation Analysis of a Cold Coiled Strip in Coiling Process (냉연 판재의 권취공정에 있어서 장력/열/변형 해석)

  • 정영진;이규택;강충길
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.39-43
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    • 2002
  • A new model for heat transfer and thermal deformation analysis according to strip mm in coiling process has been proposed. Finite difference analyses for heat transfer of cold rolled coil have been carried out under various coiling tensions and strip crown using the equivalent thermal conductivity for the radial direction of cold rolled coil which is a function of strip thickness, surface characteristics and compressive pressure. The compressive pressure is calculated from a equation expressed as a function of hoop stress and coil tension considering strip mm obtained by experiment. Finite element method for thermal deformation of cold rolled coil has been performed to investigate the effects of the strip crown, the coil tension and temperature. From these analyses, it is found that the axial inhomogeneity of thermal deformation is increased as the strip crown, compressive pressure, and temperature drop in cold coiled strip increase.

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Development and Characteristics of a New Insulator between Turns of Superconducting Coil (초전도 Coil의 새로운 turn간 절연재료의 개발 및 특성)

  • 박영욱;이동성;이정원;곽동순;김상현
    • Progress in Superconductivity and Cryogenics
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    • v.4 no.1
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    • pp.26-29
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    • 2002
  • Polyimide-epoxysilane (coupling agent) composites were reacted with oligomeric PDMS, a condensation product of difunctional silane, by a sol-gel process and were then dried into films. And then, the surface, mechanical, and electric properties were measured. The study showed that PDMS existed in the polymide matrix by the use of FT-IR. In the mechanical properties, the maximum elongation and toughness was increased in the polyimide with silane-groups. But the maximum tensile strength was slightly decreased. And the intensive dispersion of the silane-groups on the surface of polyimide was ascertained through XPS measurement. In the electric properties. AC break down voltage was increased by increasing the amount of difunctional silane. This experiment showed that PDMS added polyimide had better mechanical and electric properties than classical materials.

3T MR Imaging에 적합한 RF Surface Coil의 개발 : 피부 미세구조에 대한 예비 연구

  • 윤성익;이정우;최보영;이형구;서태석
    • Proceedings of the Korean Society of Medical Physics Conference
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    • pp.48-48
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    • 2003
  • Abstract: 현대 질병의 최종진단은 세포수준의 해부형태학적 연구가 일반적이며 광학현미경이나 전자현미경을 이용한 병리조직학적 소견을 바탕으로 진단되어지고 있다. 이러한 진단에는 In vivo 검사가 거의 불가능하여 주로 생검을 통한 연구만 수행되고 있어 진단함에 있어 단계적인 불편이 초래될 뿐만 아니라 악성 종양의 전이를 유발시킬 수 있고 또한 생리 및 생화학적 분석이 어렵다. 이러한 문제점을 해결하기 위해 고분해능의 RF Surface Coil을 개발하여 In vivo 및 비침습적인 방법인 MR Technology를 이용하고자 한다. Introduction: 피부조직과 같은 미세 인체구조 연구를 위해 고해상도 3T MRI 시스템에 적합한 고분해능의 RF surface coil을 개발하고 있다. In vivo 연구를 위한 여러 parameter를 최적화하여 기능영상에도 부합된다. 비침습적인 In vivo 검사에 의한 세포수준의 극 미세구조의 연구가 가능해짐으로써 과거 시행하던 침습적인 생검없이 각종질환의 진단적 접근이 병리학적 수준으로 향상되어 질병의 정확한 진단이 가능해지게 될 것이다. Method: 고분해능의 RF Surface Coil을 제작하여 3T MR 장비에서 피부 미세구조연구에 보다 적합하도록 In vivo 및 In vitro 실험을 수행하였다. In vitro 실험은 In vivo 연구를 위한 여러 parameter들을 최적화하기 위한 기초 실험을 하였고 다양한 팬톰들을 이용하여 Tl 강조영상, T2 강조영상을 획득하였으며, SNR을 높이기 위한 개선에 대한 연구를 수행하였다. In vivo 실험은 정상피부에서 다양한 부위에 대한 피부영상의 예비 연구를 수행하였다. Result and Discussion: 비침습적인 In vivo 검사에 의한 세포수준의 극 미세구조의 연구가 가능해짐으로써 과거 시행하던 침습적인 생검없이 각종질환의 진단적 접근이 병리학적 수준에서 가능해짐으로써 질병의 정확한 진단이 가능해지게 될 것이다. Acknowledgement: 본 연구는 2002 년도 한국과학재단 목적기초연구사업 (과제번호 : R0l-2002-000-00294-0 (2002)) 지원아래 수행되었다.

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Study on the Critical Current of Field Coil for High Temperature Superconducting Motor (고온초전도 전동기용 계자코일의 임계전류 연구)

  • Jo, Young-Sik;Sohn, Myung-Whan;Baik, Seung-Kyu;Kwon, Woon-Sik;Lee, Eon-Yong;Kwon, Young-Kil
    • Proceedings of the KIEE Conference
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    • pp.873-875
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    • 2003
  • It is well known that $I_c$ (critical current) in HTS tape is more sensitive to $B{\perp}$ (magnetic field amplitude applied perpendicular to the tape surface) than to B// (magnetic field amplitude applied parallel to the tape surface). Thus, the magnitude of $B{\perp}$ at HTS tape is important to the design of HTS motor, because it determines the operating current. In addition, the $I_c$ of HTS field coil is determined by not only the $B{\perp}$ but also stress and strain condition at given operating temperature. Therefore, at the stage of field coil design, stress and strain conditions should be considered because when the HTS tape is handled, it is necessary to know the limiting values of loading, bending and twisting to avoid any damages. The $I_c$ of field coil is calculated by 3D analysis and measured through experiments considering the $B{\perp}$ and the margin of contacts loss.

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Thermal Design of a Cooling Coil for Building Air Conditioning (건물 공조용 냉수 코일의 열 설계)

  • Kim, Nae-Hyun;Byun, Ho-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.10
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    • pp.6445-6452
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    • 2015
  • The surface of the cooling coil becomes dry, wet or partially wet depending on the operating condition. Thus, a proper design of the cooling coil should include a heat transfer analysis on dry, wet or partially wet surfaces. In this study, an elementary model, which analyzes the cooling on an elementaty basis, is proposed. Comparison of the predictions of the model with experimental data of the cooling coil revealed that heat transfer rates were predicted within 10.1%, airside pressure drop within 11.1% and sensible heat ratio within 5.7%. The model was used to investigate the effect of water circuitory on cooling coil performance.

Surface Characteristics of Solvent-Cast Cellulose Acetate (용매 성막 셀룰로오스 아세테이트의 표면특성)

  • 이기정;하완식
    • Textile Science and Engineering
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    • v.19 no.5
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    • pp.27-36
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    • 1982
  • The effects of solvent properties on the surface characteristics of solvent-cast cellulose acetate were investigated. The films of cellulose acetate 54.3% of acetyl value were cast from the solutions varying in thermodynamic quality, and the film properties were studied by means of surface tension measurements. In the surface properties such as the surface free energy, consisting of dispersion and polar contrbutions. and the work of adhesion, significant variations were observed and these were correlated to f-values defined as the balance of solubility parameter and the hystersis on the rough surface. To evaluate the degree of surface roughness, a parameter as the measure of coil dimensions in solution, ($\frac{1}{2}$-XH)/V1 was used on the assumption that the degree of surface roughness is proportional to the magnitude of the coil dimensions.

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