• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.77-77
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• 2002

목적： We has proposed a surface coil which has improved SNR compared with the standard head coil. Usually, a cylindrical head coil provide good homogeneity but less SNR than surface coil. A surface coil has better SNR at the expense of image homogeneity. In this paper, a surface coil of transmit-receive mode offers a better SNR as compared with a head coil.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.16-16
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• 2003

Purpose： Recently, a major interesting method of fast MR imaging is sensitivity encoding (SENSE) using arrays of multiple receiver coils. In this study, we have designed and implemented a 4-channel head array coil and optimized the structure and arrangement of the coil to improve the performance.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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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.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.363-364
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• 2002

We describe quadrature type surface coil for functional magnetic resonance imaging at 3T MRI system. The coil consisted of two coplanar resonators and was used as both transmitter and receiver. The signal-to-noise ratio (SNR) of the coil was compared with that of a standard birdcage head coil. Visual cortex activation on normal subjects using LED flicker was performed. The SNR of surface coil was found to be better than that of the conventional head coil.

• Journal of Magnetics
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• v.13 no.4
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• pp.177-181
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• 2008

A very simple a.c. magnetic susceptometer for use in a helium closed cycle cryostat is reported in this paper. This simple setup has only a single bobbin-less copper coil, instead of the primary coil and two secondary coils typically used in mutual-inductance types. The single bobbin-less copper coil is directly mounted on the cryostat cold head. A sample is attached on the inside wall of the copper coil using a thermal contact material and its a.c. magnetic susceptibility is obtained from the measurement of the self-inductance of the sample coil using an LCR meter or an impedance analyzer. Experimental details are described and illustrative measurements on magnetic and superconducting materials as a function of temperature are included. The performances and limitations of this simple a.c. magnetic suceptometer are also discussed.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.5
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• pp.38-43
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• 2009

We derive an equation that predicts the induced voltage across the receiving terminals of the three-coil head of a metal detector using a magnetic vector potential approach. We also derive an equation that relates the change of the impedance of the transmitting coil to the properties of the metal. We utilize the results to obtain the optimum spacing between the driving and the receiving coils at which the maximum induced voltage is attained. Further, we determine the position of the metallic object where the voltage reaches its peak. We verify our work by comparing the results with those of a previous work.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.177-177
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• 2001

목적： Head coil이나 Knee coil로 촬영하기에 부피가 작은 신체의 부위나 동물을 촬영하기 위하여 3T small birdcage coil을 개발하고 실험을 통해 코일의 효율성을 조사하였다. 대상 및 방법： 원통형 아크릴과 구리테이프를 사용하여 원통의 내경이 Knee coil보다 작은 8개의 elements를 가진 birdcage coil을 설계 제작하였고 팬톰, 지원자, 동물에 대한 MR 영상으로 그 가치를 평가하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.314-319
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• 2008

In this paper, the electric field distribution induced inside the brain during Transcranial Magnetic Stimulation(TMS) has been thoroughly investigated in terms of tissue heterogeneity and anisotropy as well as different head models. To achieve this, first, an elaborate head model consisting of seven major parts of the head has been built based on the Magnetic Resonance(MR) image data. Then the Finite Element Method(FEM) has been used to evaluate the electric field distribution under different head models or three different conductivity conditions when the head model has been exposed to a time varying magnetic field achieved by utilizing the Figure-Of-Eight(FOE) stimulation coil. The results show that the magnitude as well as the distribution of the induced field is significantly affected by the degree of geometrical asymmetry of head models and conductivity conditions with respect to the center of the FOE coil.

• Proceedings of the KSMRM Conference
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• 1999.11a
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• pp.97-97
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• 1999

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.3
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• pp.316-321
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• 2004

In this paper, we have developed a new mounting head system for flip chip. The proposed head system consists of a macro/micro positioning actuator for stable force control. The macro actuator provides the system with a gross motion while the micro device yields fine tuned motion to reduce the harmful impact force that occurs between very small sized electronic parts and the surface of a PCB(printed circuit board). In order to show the effectiveness of the proposed macro/micro chip mounting system, we compared the proposed system with the conventional chip mounting head equipped with a macro actuator only. A series of experiments were executed under the mounting conditions such as various access velocities and PCB stiffness. As a result of this study, a satisfactory voice coil actuator as the micro actuator has been developed, and its performance meet well the specifications desired for the design of the chip mounting head system and show good correspondence between theoretical analysis and experimental results.