• Title, Summary, Keyword: Surface Coil

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Functional MRI study with surface coil in 3T MRI

  • 추명자;최보영;이형구;서태석
    • Proceedings of the KSMRM Conference
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    • pp.149-149
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    • 2001
  • 목적: Birdcage coil보다 SNR이 높은 Surface coil을 이용하여 시각 자극에 대한 반응 정도의 차이를 보이고자 한다. 대상 및 방법: 연구 개발 중인 Magnum 3.0T로 영상을 얻었다. 실험 대상자는 정상인 지원자로 하였고, 10Hz로 깜박거리는 발광다이오드를 이용하여 시각 자극을 실행하였다. 일정 paradigm으로 얻어진 영상은 SPM으로 분석하였다.

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Development of Smart Tape Attachment Robot in the Cold Rolled Coil with 3D Non-Contact Recognition (3D 비접촉 인식을 이용한 냉연코일 테이프부착 로봇 개발)

  • Shin, Chan-Bai;Kim, Jin-Dae
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.11
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    • pp.1122-1129
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    • 2009
  • Recently taping robot with smart recognition function have been studied in the coil manufacturing field. Due to the difficulty of 3D surface processing from the complicated working environment, it is not easy to accomplish smart tape attachment motion with non-contact sensor. To solve these problems the applicable surface recognition algorithm and a flexible sensing device has been recommended. In this research, the fusion method between 1D displacement and 3D laser scanner is applied for robust tape attachment about cold rolled coil. With these sensors we develop a two-step exploration and the smart algorithm for the awareness of non-aligned coil's information. In the proposed robot system for tape attachment, the problem is reduced to coil's radius searching with laser displacement sensor at first, and then position and orientation detection with 3D laser scanner. To get the movement at the robot's base frame, the hand-eye compensation between robot's end effector and sensing device should be also carried out respectively. In this paper, we examine the auto-coordinate transformation method in the calibration step for the real environment usage. From the experimental results, it was shown that the taping motion of robot had a robust under the non-aligned cold rolled coil.

Breakdown Properties for Electrical Insulation Design of Double Pancake Coil Type HTS Transformer (Double Pancake Coil형 고온초전도 변압기의 전기적 절연 설계를 위한 절연파괴 특성)

  • Baek, Seung-Myeong;Jung, Jong-Man;Kim, Sang-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.52-57
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    • 2002
  • High temperature superconductors can only be applied against an engineering specification that has to be determined for each particular application form the design requirements for economic viability and for operation margins in service. However, in order to realize the HTS transformer, it is necessary to establish the high voltage insulation technique in cryogenic temperature. Therefore, the composite insulation of double pancake coil type transformer are described and ac breakdown voltage characteristics of liquid nitrogen($LN_{2}$) under HITS pancake coil electrode made by Bi-2223/Ag are studied. Breakdown in $LN_{2}$ is dominated electrode shape and distance. And we investigated AC breakdown properties of $LN_{2}$ and complex conition of cryogenic gaseous nitrogen($CGN_{2}$) obove a $LN_{2}$ surface. Also, the surface voltage of GFRP was measured as a function of thickness and electrode distance in $LN_{2}$ and complex condition of $CGN_{2}$ above a $LN_{2}$ surface. This research presented information of electrical insulation design for double pancake coil type HTS transformer.

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A Comparative Study of SNR and Image According to the Aplication Coil in MRI Inspection (자기공명영상검사에서 Coil적용에 따른 SNR과 영상의 비교연구)

  • Park, Ye-won;Lim, Cheong-hwan
    • Proceedings of the Korea Contents Association Conference
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    • pp.147-148
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    • 2015
  • MRI검사 시 다양한 환자를 고려한 변화에 적절한 coil의 선택과 조건에 따른 SNR의 차이를 조사하여 우수한 SNR의 영상을 획득하고자 한다. MR영상 획득실험은 Bottle Phantom를 이용하여 Philips achieva 1.5T와 SIMENS 1.0T을 이용하여 sequence별, surface coil별로 MR영상을 획득하여 SNR를 구하였다. 주자장이 1.0T에서 가장 높은 SNR은 TSE와 FLAIR에서 knee coil, GE에서 head coil로 측정되었고, 주자장이 1.5에서 가장 높은 SNR은 TSE에서 head coil, FLAIR와 GE에서 knee coil로 측정되었다. 본 연구에서 획득한 결과를 중심으로 다양한 환자를 고려한 변화에 따른 적절한 coil의 선택과 조건에 따라 SNR의 차이를 조사하여 우수한 SNR의 영상을 제시하여야 한다.

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자기공명 영상촬영을 위한 임의로 선택된 모양의 최소인덕턴스 경사자계코일의 설계 (Minimum-Inductance MRI Gradient Coil Design with Arbitrarily-Selected Shape)

  • Lee, J.K.;Yang, Y.J.;Yi, Y.;Cho, Z.H.;Oh, C.H.
    • Proceedings of the KOSOMBE Conference
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    • v.1994 no.05
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    • pp.85-87
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    • 1994
  • This paper proposes a new inductance minimization scheme for a gradient system of arbitrarily selected shape. Although it is important to minimize the gradient coil inductance to reduce the current switching time, such minimization has been possible only for cylindrical or parallel biplanar coils. By using small current loops on arbitrarily selected surface as optimization elements, the inductance of the whole circuit can be minimized using the loop's self- and mutual-inductances. Wire positions can be easily derived from the loop current distribution. Preliminary studies for the design of x-directional surface gradient coil show the utility of tile proposed gradient coil design scheme.

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Study on fabricated RF coil using high-temperature superconductor tape and matching circuit for low field MRI system (고온초전도 선재와 정합회로를 이용한 RF coil 제작에 대한 기초연구)

  • Kim, D.H.;Ko, R.K.;Kang, B.M.;Ha, D.W.;Sohn, M.H.;Mun, C.W.
    • Progress in Superconductivity and Cryogenics
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    • v.14 no.1
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    • pp.44-47
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    • 2012
  • The substantial improvement of the signal-to-noise ratio (SNR) can be achieved with small-size samples or low-field MRI system by high-temperature superconducting(HTS) RF coil. The typical HTS RF coil made of HTS thin film is expensive and is limited the coil geometry to planar surface coil. In this study, commercial Bi-2223 HTS tapes was used as RF coil for a 0.35T permanent MRI system. It has advantages of both much lower cost and easier fabrication over HTS thin film coil. SNR gain of the image obtained from the HTS RF coil over a conventional Cu RF coil at room temperature was about 2.4-fold and 1.9-fold using the spin echo pulse sequence and gradient echo pulse sequence respectively.

An Experimental Study on tee Heat Transfer Enhancement Effect of the Coil Fins for Ice Storage System (빙축열 시스템에서의 코일 휜의 열전달 촉진 효과에 관한 실험적 연구)

  • 성병호;이분희;임광빈;김철주
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • pp.219-224
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    • 2004
  • The present study was to investigate the heat transfer enhancement effect of coil wire fins in an ice storage system. For the two cases of tubes with internal brine flows, a finned tube with coil wires on its outer surface and a smooth tube, the rates of ice layer were tested and compared for both the icing processes. The coil fins were made of a stainless steel wire with a dia. of 2.0(mm), and the coil had an outer dia. of 10(mm) and a helix angle of 60($^{\circ}$). The experimental results showed that the coil fins could substantially reduce the thermal resistance of the ice layer, and enhance the heat flow rates between the water in the storage tank and the brine. The ice storing time was found to be shortened by 13(%) for the coil fins to get the same amount of ice layer that was built on the smooth tube wall for 10 hours of operation when the same thermal conditions were provided.

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Dielectric Insulation Properties of Double Pancake Coil Type HTS Transformer (Double Pancake Coil형 고온초전도 변압기의 전기적 절연 특성)

  • 백승명;정종만;이현수;한철수;김상현
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.2
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    • pp.151-156
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    • 2003
  • High temperature superconductor can only be applied against an engineering specofication that has to be determined for each particular application form the design requirements for economic viability and for operation margins in service. However, in order to realize the HTS transformer, it is necessary to establish the high voltage insulation technique in cryogenic temperature. Therefore, the composite insulation of double pancake coil type transformer are described and AC breakdown voltage characteristics of liquid nitrogen(LN$_2$) under HTS pancake coil electrode made by Bi-2223/Ag are studied. The Breakdown of LN$_2$ is dominated electrode shape and distance. The influence of pressure on breakdown voltage is discussed with th different electrode. For the electrical insulation design of turn-to-turn insulation for the HTS transformer, we tested breakdown strength of insulation sheet under varying pressure. And we investigated surface flashover properties of LN$_2$ and complex conition of cryogenic gaseous nitrogen(CGN$_2$) obove a LN$_2$ surface. The surface voltage of GFRP was measured as a function of thickness and electrode distance in LN$_2$ and complex condition of CGN$_2$ above a LN$_2$ surface. this research presented information of electrical insulation design for double pancake coil(DPC) type HTS transformer.

Process Design, Fabrication, and Evaluation of Cold Drawn SUS304N Coil Wedge (SUS304N 코일 웨지 인발 공정의 설계, 제조 및 평가)

  • Jung, J.E.;Kim, S.J.;Bae, S.;Namkung, J.;Kim, S.M.;Kim, S.I.;Lee, K.S.
    • Transactions of Materials Processing
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    • v.28 no.4
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    • pp.212-218
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    • 2019
  • In this study, the first drawing die for the production of coil wedge is redesigned in order to enhance properties such as dimensional accuracy, dimensional uniformity, non-magnetism, and residual stress. The equivalent strain distribution is observed to be asymmetric at certain corners of the product and un-filling of material is also observed at the same location, based on the results of FEM simulation for the current drawing process. Additionally, a relatively huge amount of deformation is concentrated on the surface of the reference product leading to an increase in magnetic component and surface residual stress. After re-designing the cross-section of the first drawing step process conformed to relatively higher amount of reduction ratio, reduction of both surface residual stress and the volume fraction of magnetic component could be achieved for the finally-drawn coil wedge product.

Usefulness of the Technique of Collecting Signals by Selecting Elements from RF Receive Phase Array Coil in Magnetic Resonance Imaging (자기공명영상검사 시 Array coil에서 element를 선택하여 신호를 수집하는 기법의 유용성)

  • Choi, Kwan-Woo;Son, Soon-Yong
    • The Journal of the Korea Contents Association
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    • v.18 no.6
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    • pp.461-466
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    • 2018
  • In this study, we investigated the signal intensity changes by activating all and partially selected coil elements as a way to increase the SNR in a single region MR imaging. Two cylindrical fluid phantoms were placed side by side in a phase array coil and MRI scans were repeated by turning on the entire elements and selected elements. As a result, on both of the T1 and T2 weighted images signal intensities were significantly increased by 5.49% and 14.64%, respectively. In conclusion, if only a single region was to be imaged, selecting appropriate elements and collecting signals only from them could easily improve image qualities and signal intensities.