• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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• pp.340-347
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• 2004

Ultra-small size, high-performance, solenoid-type RF chip inductors utilizing low-loss A1$_2$O$_3$ core materials were investigated. The dimensions of the RF chip inductors fabricated were 1.0mm${\times}$0.5mm${\times}$0.5mm and copper coils were used. The materials (96％ A1$_2$O$_3$) and shape (I-type) of the core, the diameters (40${\mu}{\textrm}{m}$) and position (middle) of the coil, and the lengths (0.35mm) of solenoid were determined by a high-frequency structure simulator (HFSS) to maximize the performance of the inductors. The high-frequency characteristics of the inductance (L) and quality-factor (Q) of the developed inductors were measured using a RF impedance/material analyzer (E4991A with E16197A test fixture). The developed inductors exhibit an inductance of 11 to 11.3nH and a qualify factor of 22.3 to 65.7 over the frequency ranges of 250 MHz to 1.7 GHz, and show results comparable to those measured for the inductors prepared by Coilcraft$^{TM}$. The simulated data described the high-frequency data of the L and Q of the fabricated inductors well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1154-1159
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• 2006

The mold transformers have been widely used in underground substations of large building and have some advantages when compared with oil-transformer. Those advantages are low fire risk, environmental compatibility, compact size and high reliability. The mold transformer is generally known to have cooling duct between low voltage and high voltage coil. To achieve better compact structure and low loss, mold transformers made by one body molding method has been developed. Nevertheless, such kinds of transformer need better cooling method because heat radiation between each winding is still of problem. The life of transformer is significantly dependent on the thermal behavior in windings. Many designers have calculated temperature distribution in transformers and hot spot point by finite element method(FEM) to analyze winding temperature rise. In this paper, the temperature distribution analysis of 100 kVA pole mold transformer for power distribution were investigated by FEM program and the thermal analysis results were compared with temperature rise test.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.3
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• pp.107-115
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• 2003

This paper deals with the effect of the auxiliary pole core in the automotive starter motor on its characteristics. This motor is excited by the permanent magnet and has auxiliary pole core in the stator. The auxiliary pole core is a device to increase the effective flux to obtain the starling torque and prevent the demagnetization of the permanent magnet from the starting current. It Is important to design the auxiliary pore core. And overhang structure causes the electromagnetic phenomenon of 3-dimensional flux Path. Therefore. the characteristic analysis is achieved by the 2-dimensional Finite Element Method (FEM) with the compensated model and the 3-dimensional Equivalent Magnet Circuit Network (3D EMCN). The mechanical loss and the brush and coil resistance are separated from the various experiment of the tested motor, and then these factor are reflected on the analysis results. The validity of the proposed analysis method is verified by comparing the experimental and analysis results. The effects of the design parameters related to the auxiliary pole cote on the motor performance are analyzed by the proposed method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1176-1179
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• 2003

Low-Pressure inductively coupled RF discharge sources have important industrial applications mainly because they can provide a high-density electrodeless plasma source with low ion energy and low power loss. In an inductive discharge, the RF power is coupled to the plasma by an electromagnetic interaction with the current flowing in a coil. In this paper, the experiments have been focussed on the electric characteristic and carried out using a single Langmuir probe. The internal electric characteristics of inductively coupled Ar RF discharge at 13.56 [MHz] have been measured over a wide range of power at gas pressure ranging from $1{\sim}70$ [mTorr].

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1863-1872
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• 2001

In this Paper, we suggest the precision stage using a novel non-contact planar actuator that utilizes an interaction between an array type of air-core solenoids and permanent magnets. The former with axes arranged in the mutually orthogonal direction is fixed on the stator and the latter with the same polar direction is attached below the stage. The promising magnetic structure has little uncertainty such as hysteresis loss caused by ferromagnetic material, then it is simple to quantify the magnetic phenomenon. And all the magnetic forces are transmitted through narrow air-gap between the coil and the permanent magnet, therefore the structure can be highly compacted. Furthermore, the stage or plate can be perfectly isolated from the stator without any wire connection, leading to diminish the generating possibility of wear particles due to mechanical contact. Then. it is estimated that the proposed operating principle is very suitable for work requiring high accuracy and cleanness. or general-purpose nano stage. The main issues rebated to the plate driving are discussed here.

• Progress in Superconductivity
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• v.2 no.1
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• pp.20-26
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• 2000

A 40-channel superconducting quantum interference device (SQUID) system was constructed for measuring neuromagnetic fields. Main features of the system are the use of double relaxation oscillation SQUIDs (DROSs), and planar gradiometers measuring magnetic field components tangential to the head surface. The DROSs with high flux-to-voltage transfers enabled direct readout of the SQUID output by room-temperature dc preamplifiers and simple flux-locked loop circuits could be used for SQUID operation. The pickup coil is an integrated first-order planar gradiometer with a baseline of 40 mm. Average noise level of the 40 channels is around 1.2 $fT/cm/{\surd}Hz$ at 100 Hz, corresponding to a field noise of 5 $fT/{\surd}Hz$, operated inside a magnetically shielded room. The SQUID insert was designed to have low thermal load, minimizing the loss of liquid helium. The constructed system was applied to measure auditory-evoked neuromagnetic fields.

• Journal of Korean Neurosurgical Society
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• v.57 no.3
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• pp.204-207
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• 2015

We are reporting an unusual case of dural arteriovenous fistula (AVF) of the superior sagittal sinus (SSS) after tamoxifen treatment for breast cancer. A 30-year-old female arrived at the emergency room with a sudden headache and left sided weakness and sensory loss. In her past medical history, she was diagnosed with breast cancer 1 year prior, and subsequently underwent a breast conserving mastectomy with whole breast radiation and adjuvant chemotherapy with tamoxifen. At the time of admission, computed tomography showed a small acute intracerebral hemorrhage at the right parietal cortex, and magnetic resonance imaging showed that a dural AVF at the SSS with a prominent and tortuous venous enhancement along the centrum semiovale was present. Cerebral angiography showed that the dural AVF at the mid-portion of the SSS with meningeal arterial feeding vessels entering the wall of the SSS, then draining through the dilated cortical veins. Our patient had no signs of active malignancy or any abnormalities in her coagulation profile, so it can be concluded that the tamoxifen was the likely cause of the SSS thrombosis and dural AVF. The dural AVF was treated by an endovascular coil embolization for the arterialized segment of the SSS. The patient dramatically recovered favorably from left side motor and sensory deficit. The best clinical approach is to screen potential patients of tamoxifen hormonal therapy and educate them on the sign and symptoms of life threatening thromboembolic events while taking tamoxifen.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.439-449
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• 2011

The temperature distribution and subsequent permanent deformation of SS400 carbon steel plate subjected to an induction-based line heating process were studied by a numerical method involving coupled 3-D electromagnetic-thermal-structural analysis. The numerical study revealed that the amount of permanent deformation is strongly related to the Joule loss caused by such process conditions as input power and moving speed of the heat source. To validate the numerical analysis results, line heating experiments were carried out with a high frequency(HF) induction heating(IH) equipment capable of bending thick plate with the moving accuracy of ${\pm}0.1mm$ in heating coil position. The amount of permanent deformation increased with decreasing moving speed and increasing input power.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2103-2105
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• 1998

Switched Reluctance Motor is simple structure which used Accel/Decel application field because of cheap cost and High efficiency. For driving this motor, it is essential to need position sensor and driving converter. so, many topology and sensor have been studied untill now. Asymmetric Bridge Converter which has been known for the best control and efficiency is used chopping to control current of motor coil according to changing of motor speed. But this is embossed as a fault because it come to bring switching loss due to rapid switching frequency. In this paper, I applied to Soft Switching Mode by Partial Resonant Method to compensate these fault and to show the usabilityness of low switching device.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.121-128
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• 1998

A new magnetic ballast was designed and developed to get high luminous efficiency. The core material of new magnetic ballast was G-9 and its shape of core is modified. The diameter of the coil was upgraded to 0.5[mm], and a new power-saving circuit was designed for the semiconductor ignition starter. The experimental results of the ballast showed reduction of the electric loss in the magnetic ballast about 1.7Watt (0.5[%]). The luminous efficiency was increased by 6.2 lm/Watt (7.6[%]) and the ballast efficiency factor(BEF) of 1.09(7.6[%]). The prototype was tested through national standard testing procedure. A high efficient energy-using equipment (the second grade in the efficiency of energy consumption) was certified. The saving power of 1.7[W] was shown by lighting appratus for fluorescent lamps. The result will be used for the high efficient magnetic ballast technology.nology.