• 한국초전도ㆍ저온공학회논문지
• /
• 제17권2호
• /
• pp.41-44
• /
• 2015

Critical current of high-temperature superconducting (HTS) coil is influenced by its own self magnetic field. Direction and density distribution of the magnetic field around the coil are fixed after the shape of the coil is decided. If the entire part of the HTS tape has homogeneous $I_c$ distribution characteristic, quench would be initiated in fixed location on the coil. However, the actual HTS tape has inhomogeneous $I_c$ distribution along the length. If the $I_c$ distribution of the HTS tape is known, we can expect the spot within the HTS coil that has the highest probability to initiate the quench. In this paper, $I_c$ distribution within the HTS coil under self-field effect is simulated by MATLAB. In the simulation procedure, $I_c$ distribution of the entire part of the HTS tape is assume d to follow Gaussian-distribution by central limit theorem. The HTS coil model is divided into several segments, and the critical current of each segment is calculated based on the-generalized Kim model. Single pancake model is simulated and self-field of HTS coil is calculated by Biot-Savart's law. As a result of simulation, quench-initiating spot in the actual HTS coil can be predicted statistically. And that statistical analysis can help detect or protect the quench of the HTS coil.

• 한국초전도ㆍ저온공학회논문지
• /
• 제16권4호
• /
• pp.44-48
• /
• 2014

A liquid nitrogen-cooled prepolarization ($B_p$) coil made for ultra-low field nuclear magnetic resonance and magnetic resonance imaging (ULF-MR) designed to generate 7 mT/A was fabricated. However, with suspected internal insulation failure, the coil was investigated in order to find out the source of the failure. This paper reports detailed build of the failed $B_p$ coil and a number of analysis methods utilized to figure out the source and the mode of failure. The analysis revealed that pyrolytic graphite sheet linings put on either sides of the coil for better thermal conduction acted as an electrical bridge between inner and outer layers of the coil to short out the coil whenever a moderately high voltage was applied across the coil. A simple model circuit simulation corroborated the analysis and further revealed that the failed insulation acted effectively as a damping resistor of $R_{d,eff}=6{\Omega}$ across the coil. This damping resistance produced a 50 ms-long voltage tail after the coil current was ramped down, making the coil not suitable for use in ULF-MR, which requires complete removal of magnetic field from $B_p$ coil within milliseconds.

• 한국전자파학회논문지
• /
• 제26권4호
• /
• pp.389-396
• /
• 2015

펄스 유도(Pulse Induction) 방식의 금속 탐지기 코일 설계에 대하여 살펴보았다. 0.3 mm, 0.5 mm, 1.0 mm의 직경을 갖는 도선과 $30cm{\times}30cm$ 및 $35cm{\times}35cm$ 크기의 유전체 탐지판을 이용하여 탐지 코일을 제작하였고, 코일 크기와 코일 감은 수 등의 파라미터 변화에 따른 코일 시정수 및 코일 전류 등의 특성을 살펴보았다. 도선의 직경, 코일 크기 및 코일 감은 수 변화에 따른 코일의 인덕턴스, 저항 및 시정수 값에 대하여 계산 결과와 측정 결과를 비교 분석하였다. 또한, 입력 펄스폭 변화에 따른 탐지 코일의 전류 변화에 대하여 계산 결과와 측정 결과를 비교 분석함으로써 펄스 유도 방식의 금속탐지기 코일 설계에 대하여 논하였다.

• 한국전기전자재료학회논문지
• /
• 제22권1호
• /
• pp.1-6
• /
• 2009

Air core based transformers have been designed, simulated and fabricated by using micromachining process for the application of wireless power transmission with the range of frequency from 1 GHz to 20 GHz. Fabricated transformers are the types of solenoid transformers with primary and secondary coils. the size of fabricated transformer is $1.1{\times}1.5{\sim}2.15\;mm$ including ground shield. Transformers have been measured by dividing two groups based on the turns ratio between primary coil and secondary coil which are 1:1 transformers(the number of turns of primary coil and secondary coil: 3/3, 5/5, 7/7) and l:n transformers(the number of turns of primary coil and secondary coil: 3/3, 3/6, 3/9). As a result of the measurement, the lowest insertion loss of transformers ranged from 2 dB to 2.8 dB according to the number of turns between primary coil and secondary coil. And the lowest insertion loss from the transformers was measured at the frequency from 7 GHz to 11 GHz according to the number of turns between primary coil and secondary coil. Based on the measurement data from the microfabricated transformers, the transformer with the 3/3 turns in the primary coil and secondary coil showed best performance compared to others in terms of lowest insertion loss, lowest insertion loss frequency and bandwidth.

• 자연과학논문집
• /
• 제17권1호
• /
• pp.103-111
• /
• 2006

호알칼리성이며 고온성인 Bacillus sp. TA-11이 세포내로 생성하는 invertase 유전자를 대장균에 클로닝 시켜 얻은 재조합 E. coil pYC17의 invertase 생합성 조절양상을 조사 하였다. 재조합 E. coil의 invertase는 30 mM sucrose에 의해 3시간에 가장 효과적으로 유도 되었으며 조합 E. coil pYC17의 sucrose에 의한 invertase 유도는 10 mM의 glucose 농도에서 심하게 억제 되었다. 이러한 재조합 E. coil pYC17에서의 invertase 생합성 조절 양상은 친주인 Bacillus sp. TA-11과 유사하였으나 저해농도는 낮았다.

• 한국전자통신학회논문지
• /
• 제7권4호
• /
• pp.861-866
• /
• 2012

현재까지 코일을 이용한 자성물질 가속에 코일과 자성물질간의 최적한 거리를 명시한 적이 없다. 전류세그먼트 코일구조와 그 다단계를 이용하여 자성물질을 가속 시 통상 코일과 자성 물질이 가깝게만 있으면 최적한 것으로 알고 있으나 미분법으로 극대점을 찾은 결과 코일간의 거리에 대한 절반위치에 있을 때 최적한 거리임을 알 수 있다. 여러 개의 상하 전류세그먼트 코일구조를 만들어 전류세그먼트 코일구조가 자성물질인 강구를 최적한 거리에서 가속할 수 있는지 확인하였다. 강구의 질량에 대한 코일 최소 전류를 실험으로 알았고 그 결과 코일 건이나 자성물질, 자성유체에 적용 시 코일과 물질 간에 최적 거리를 해결 하였다.

• 조명전기설비학회논문지
• /
• 제25권2호
• /
• pp.61-68
• /
• 2011

The circuit breaker of power distribution board is essential part for the protection of electrical disaster from load short, trouble of power system. For the normal operation of circuit breaker, trip coil of the circuit breaker can cut the mechanical contact of circuit breaker from the detection of power system troubles. This paper presents a design and experimental results of trip coil fault detection system for the real time monitoring of the circuit breaker. The designed system is consisted by the trip coil fault detector which is connected to the each circuit breaker and remote monitoring unit. The trip coil fault detector can detect the impedance and operating voltage of the trip coil, and the detected values are compared with the normal state. And the remote monitoring unit can be connected to the 32 channels of trip coil fault detectors by serial communication. From the designed system, the fault and normal states of the trip coil can be remotely monitored in real time. The designed system is verified by the practical circuit breaker of power distribution board. And the results shows the effectiveness of the designed system.

• 한국전기전자재료학회논문지
• /
• 제23권9호
• /
• pp.714-717
• /
• 2010

The improved flux-lock type superconducting fault current limiter (SFCL) is composed of a series transformer and superconducting unit of the yttrium-barium-copper-oxide (YBCO) coated conductor. In this paper, we investigated current limiting characteristics through winding direction of coil 2 and variable number of coil 1 and coil 2 in improved flux-lock type SFCL. The better fault current characteristics and the burden of YBCO coated conductor can be confirmed from the experimental result in the higher turn ratio of coil 1 and coil 2 in the additive conditions. In case of subtractive condition, we can confirm a similar result in the same case of experimental conditions. but the burden of YBCO coated conductor has been increased from an increase in winding numbers of coil 2.

• Journal of Korean Neurosurgical Society
• /
• 제43권1호
• /
• pp.21-25
• /
• 2008

Objective : Both endovascular coil embolization and microsurgical clipping are now firmly established as treatment options for the management of cerebral aneurysms. Moreover, they are sometimes used as complementary approaches each other. This study retrospectively analyzed our experience with endovascular and microsurgical procedures as complementary approaches in treating a single aneurysm. Methods : Nineteen patients with intracranial aneurysm were managed with both endovascular and microsurgical treatments. All of the aneurysms were located in the anterior circulation. Eighteen patients presented with SAH, and 14 aneurysms had diameters of less than 10 mm, and five had diameters of 10-25 mm. Results : Thirteen of the 19 patients were initially treated with endovascular coil embolization, followed by microsurgical management. Of the 13 patients, 9 patients had intraprocedural complications during coil embolization (intraprocedural rupture, coil protrusion, coil migration), rebleeding with regrowth of aneurysm in two patients, residual sac in one patient, and coil compaction in one patient. Six patients who had undergone microsurgical clipping were followed by coil embolization because of a residual aneurysm sac in four patients, and regrowth in two patients. Conclusion : In intracranial aneurysms involving procedural endovascular complications or incomplete coil embolization and failed microsurgical clipping, because of anatomical and/or technical difficulties, the combined and complementary therapy with endovascular coiling and microsurgical clipping are valuable in providing the best outcome.

• 대한기계학회논문집A
• /
• 제31권1호
• /
• pp.43-49
• /
• 2007

A new electric coil design methodology using the notion of topology optimization is developed. The specific design problem in consideration is to find optimal coil configuration that maximizes the Lorentz force under given magnetic field. Topology optimization is usually formulated using the finite element method, but the novel feature of this method is that no such partial differential equation solver is employed during the whole optimization process. The proposed methodology allows the determination of not only coil shape but also the number of coil turns which is not possible to determine by any existing topology optimization concept and to perform single coil strand identification algorithm. The specific applications are made in the design of two-dimensional fine-pattern focusing coils of an optical pickup actuator. In this method, the concept of equivalent magnetizing current is utilized to calculate the Lorentz force, and the optimal coil configuration is obtained without any initial layout. The method is capable of generating the location and shape of turns of coil. To confirm the effectiveness of the proposed method in optical pickup applications, design problems involving multipolar permanent magnets are considered.