• Title/Summary/Keyword: E. coil

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A Study on Eddy-current Probe with Ferrite Cores over a Layered Half-Space (레이어가 있는 하프스페이스에서 페라이트코아가 있는 와류탐침에 대한 연구)

  • Kim, T.W.;Byun, K.R.;Choi, J.H.;Kang, E.S.;Hwang, H.J.
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.613-616
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    • 1998
  • In this paper, a model of a Eddy-current probe coil with a ferrite core in the presence of a half-space with a layer is developed. The half-space with a layer is accounted for by computing the appropriate Green's function by using Bessel transforms. Upon introducing equivalent Amperian currents within a core to explain effect to a impedance change in the coil due to a (ferrite) core, we derive a volume integral equation, The integral equation is transformed via the method of moments into a vector-matrix equation, which is then solved using a linear equation solver. Through the above processing, we computed impedance value in a Eddy-current probe coil due to a conductivity change of layer.

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Stent-assisted coiling of a ruptured basilar artery perforator aneurysm: A case report

  • Jongwon Cho;Sang Hyun Suh;Joonho Chung
    • Journal of Cerebrovascular and Endovascular Neurosurgery
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    • v.25 no.1
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    • pp.81-86
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    • 2023
  • Basilar artery (BA) perforator aneurysms are exceedingly rare causes of subarachnoid hemorrhage. Therefore, the natural history and optimal treatment have not been established, and surgical, endovascular, and conservative management have been used. However, there is no consensus on the optimal treatment strategy. Herein, we report the case of a 52-year-old man presenting with a ruptured BA perforator aneurysm. First, we deployed an Enterprise stent from the left P1 segment to the BA because the microcatheter could not enter the aneurysm. Then, we deployed a helical coil on the orifice of the BA perforator. Finally, we deployed another Enterprise stent, sandwiching the helical coil between the two Enterprise stents. The aneurysm was completely obliterated without recurrence on the follow-up angiography. Our technique of sandwiching the small helical coil between two Enterprise stents might help other surgeons by offering another feasible treatment option for ruptured BA perforator aneurysms.

Spiral Coil Magnetostrictive Strip Transducers for Long Range Ultrasonic Testing of Cylindrical Structures (실린더형 구조물의 원거리 초음파검사용 나선형 코일 자왜 스트립 변환기)

  • Heo, Won-Nyoung;Choi, Myoung-Seon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.5
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    • pp.416-420
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    • 2008
  • In EMAT field, spiral RF coils are much more widely used when compared with solenoid coils. In the field of the magnetostrictive strip transducers for long range ultrasonic testing of cylindrical structures, however, solenoid coils has been used. This seems to be attributed to the difficulty in fabricating low frequency (i.e., large size) spiral coils. In this paper, we describe a method for fabricating spiral coil magnetostrictive strip guided wave transducers from FFC (flexible flat cable). It is demonstrated through a comparison experiment that the spiral coil transducer has much superior performance (sensitivity, SNR, and guided wave direction control capability) than the previous transducer with solenoid coils.

A Study on the Optical Emission Spectroscopy of the RF Inductive Plasma Process (RF 유도형 플라즈마 프로세스에 대한 분광학적 연구)

  • Jang, Mun-Gug;Han, Sang-Bo;Park, Sang-Hyun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.11
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    • pp.103-112
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    • 2011
  • This paper is tried to analysis the optical emission spectroscopy related to the position of inductive load coil and flow rates of methane and oxygen in the RF inductive plasma process. According to the position of load coil, peak of $H_{\alpha}$, $H_{\beta}$, and CH were appeared strongly at the middle position of the coil and it decreased both direction. The electron temperature was approximately 0.9[eV] at that position. Emission intensities of $H_{\alpha}$, $H_{\beta}$, and CH increased linearly by increasing input power. In addition, intensities of $H_{\alpha}$ and $H_{\beta}$ increased by increasing the flow rate of oxygen. It might be ascribed that the oxygen species were bonded with $C_nH_m$ by suppressing the combination with hydrogen atoms. Consequently, the optimal position of the inductive coil is decided to the intermediate position between 4th and 5th turns, the wanted carbon thin-film is possible to deposit by controlling flow rates of methane and oxygen.

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.

Time dependent numerical simulation of MFL coil sensor for metal damage detection

  • Azad, Ali;Lee, Jong-Jae;Kim, Namgyu
    • Smart Structures and Systems
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    • v.28 no.6
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    • pp.727-735
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    • 2021
  • Recently, non-destructive health monitoring methods such as magnetic flux leakage (MFL) method, have become popular due to their advantages over destructive methods. Currently, numerical study on this field has been limited to simplified studies by only obtaining MFL instead of induced voltage inside coil sensor. In this study, it was proposed to perform a novel numerical simulation of MFL's coil sensor by considering vital parameters including specimen's motion with constant velocity and saturation status of specimen in time domain. A steel-rod specimen with two stepwise cross-sectional changes (i.e., 21% and 16%) was fabricated using low carbon steel. In order to evaluate the results of numerical simulation, an experimental test was also conducted using a magnetic probe, with same size specimen and test parameters, exclusively. According to comparative results of numerical simulation and experimental test, similar signal amplitude and signal pattern were observed. Thus, proposed numerical simulation method can be used as a reliable source to check efficiency of sensor probe when different size specimens with different defects should be inspected.

Design of 1 MW High-temperature Superconducting Motor with Water-cooled Armature (수냉식 전기자로 구성된 1 MW 고온초전도 동기모터의 설계)

  • Baik, S.K.;Lee, J.D.;Kim, S.H.;Lee, E.Y.;Sohn, M.H.;Kwon, Y.K.;Moon, T.S.;Park, H.J.;Kim, Y.C.;Lee, J.Y.;Hong, J.P.
    • Proceedings of the KIEE Conference
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    • 2005.07b
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    • pp.1258-1260
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    • 2005
  • Superconducting synchronous motors and generators have the field coil composed of superconductor with almost zero resistance at superconducting state. Therefore, co or loss at the conventional field coil is eliminated and the superconducting machine gets higher efficiency. The armature coil of the superconducting machine is composed of cower wire and supported by non-magnetic material such as FRP(Fiber Reinforced Plastic). Although a fully-superconducting machine with superconducting armature coil has been researched, it was not developed toward industrial application because of AC transporting loss and difficulty in construction of the cooling structure and so on. This paper contains the design procedure of a 1 MW superconducting synchronous motor using high-temperature superconductor only for the field coil. Especially, the armature coil is designed by water-cooling in order to dissipate Joule heat easily. Moreover, 3-dimensional electromagnetic design is conducted to get a proper design result and reduce design errors from 2-dimensional approach.

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Design and test results of a Rogowski coil for measurement of current distribution characteristics in 4-parallel superconducting coils (사병렬 초전도코일의 전류분류 측정을 위한 Rogowski 코일의 제작 및 특성 실험)

  • Cho, Dae-Ho;Yang, S.E.;Kim, M.J.;Ahn, M.C.;Park, D.K.;Bae, D.K.;Seok, B.Y.;Ko, T.K.
    • Progress in Superconductivity and Cryogenics
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    • v.9 no.3
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    • pp.37-40
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    • 2007
  • Large critical current is one of the prerequisites for the design of superconducting electrical equipments with large power capacity. To enlarge the critical current. multiple parallel connection is inevitable. In multiple parallel superconducting coils. the difference in normal resistance of each shunt leads to unequal current distribution. which may yield burnout. Therefore. uniform current distribution is required for a stable operation of multiple parallel superconducting coils. In this paper, Rogowski coils were fabricated to measure each shunt current of a 4-parallel superconducting coil. Four Rogowski coils were installed at the copper bars, which are used as current leads in superconducting coils. As a result, linearity of the Rogowski coils was ascertained and coefficients of each coil, the ratio of voltage and current, were derived. The coefficients were compared with theoretically calculated values. Based on the coefficients, each shunt current was calculated in a 4-parallel superconducting coil, where uniform current. distribution was confirmed. This paper verified the feasibility of the fabricated Rogowski coils as well as operational stability of the 4-parallel superconducting coil in 77K.

Measurement of Formaldehyde in the Atmosphere using a Dual-channel Glass Coil Sampler (이중 채널 유리코일 샘플러를 이용한 대기 중 포름알데하이드 측정)

  • Park Seung-Shik;Hong Sang-Bum;Lee Jai-Hoon;Cho Sung-Yong;Kim Seung-Jai
    • Journal of Korean Society for Atmospheric Environment
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    • v.22 no.2
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    • pp.259-266
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    • 2006
  • A dual-channel glass coil sampling technique was used to measure hourly formaldehyde concentration in the ambient air. The dual-channel coil sampling assembly consists of three parts; an all-pyrex 28-turn coil made of 0.2-cm internal diameter glass tubing for gas-liquid contact and scrubbing of soluble gases, an inlet section upstream of the coil for introducing sample air and scrubbing solution, and a widened glass section downstream of the coil for gas-liquid separation. The scrubbing solution used was a dilute aqueous DNPH (dinitrophenylhydrazine) solution. Hourly concentration of formaldehyde was determined at a Gwangju semi-urban site during two intensive studies between September and October using the dual channel glass-coil/DNPH sampling technique and HPLC (High Performance Liquid Chromatography) analysis. The mean concentration was 1.7($0.4{\sim}4.7$) and 3.0($0.5{\sim}19.1$) ppbv for the September and October intensives, respectively, which are considerably low, compared to those measured in polluted urban areas around the world including several urban areas of Korea. The diurnal variation showed significant increase of formaldehyde in the daytime suggesting the dominance of formation of formaldehyde due to photochemical oxidation of methane and other hydrocarbons. An increase in the formaldehyde sometimes in the night might be due to an increase in primary source, i.e. traffic emissions. It was also found that rapid increase in formaldehyde levels from 3.0 to 19.1 ppbv in the afternoon on October 20 was due to plumes from burning of agricultural wastes such as rice straw and stubble. It is expected from the measurement data that the constructed dual-channel glass coil sampling system can be utilized for measuring atmospheric concentration of the formaldehyde with high time resolution.