• Journal of the Korean Society for Precision Engineering
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• v.33 no.7
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• pp.601-606
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• 2016

In this paper, an energy harvester is developed that has advantages regarding piezoelectric noise minimization, mass production, and an easily available environmental energy source, electromagnetic induction, as well as low-frequency bandwidth and high amplitude. A process for fabricating a three-dimensional multilayered planar coil using micro-electro-mechanical systems (MEMS) on a flexible printed circuit board FPCB is introduced. Optimal shape and size were calculated via internal resistance and inductance, and a prototype was fabricated through the MEMS procedure while considering the possibility of mass production. Although the internal resistance matched the designed value, the electromotive force generated did not reach the intended amount. The main reason for the decrease in efficiency was the low area of coil outskirt exposed to the magnetic field while there was relative motion between the magnet and the coil.

• Journal of Magnetics
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• v.17 no.3
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• pp.210-213
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• 2012

To detect the surface and the opposite side cracks on iron specimen under AC and DC magnetic fields, the planar inductive coil sensors were employed. When the induced signals were measured, the planar inductive coil sensor and the magnetic field source were lifted off about 2 mm from the top surface of the specimen. AC magnetic fields and DC magnetic fields were applied to the specimens by single straight Cu coil and NdFeB permanent magnet, respectively. The detected signals at crack positions were good coincidence with those of the simulation results.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.1
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• pp.72-79
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• 1997

Most open magnetic resonance imaging systems have used the planar gradient coils whose inductances were minimized through the magnetic energy minimization procedure in the spatial frequency domain. Though the planar gradient coils have smaller inductance than conventional gradient coils, the planar gradient coils often suffer from their poor magnetic field linearity. Scaling the spatial frequencies of the current density function designed by the magnetic energy minimization, magnetic field linearity of the planar gradient coils can be greatly improved with small sacrifice of gradient coil inductance. We have found that the figure of merit of the planar gradient coils, defined by the gradient strength divided by the linearity error and the inductance, can be improved by proposed technique.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1281-1283
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• 2003

Proteins in highly oriented lipid bilayer samples are useful to study membrane protein structure determination. Planar lipid bilayers aligned and supported on glass slide were prepared. These stack of glass slide with planar lipid bilayers are not well fit for commercial solid-state NMR probe with round coil. Therefore, homebuilt solid-state NMR probe was built and used for a stack of thin glass plates and RF coil is wrapping directly around the flat square sample. The overall filling factor of the coil is much better and the large surface area enhances the extent to orientation by providing uniform environments for the phospholipids and the high ratio of circumference to area reduces edge effects. $^1H\;and\;^{15}N$ double resonance probe for 400 MHz NMR (9.4T) with a flat coil (coil size: 11 mm ${\times}$ 20 mm ${\times}$ 4 mm) is constructed and tested.

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.386-388
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• 2006

Membrane proteins in highly oriented lipid bilayer samples are useful for membrane protein structure determination. We used in the past planar lipid bilayers which were aligned and supported on the glass slide. These samples were mechanically aligned in a magnetic field. However, these stacks of glass slides with planar lipid bilayers are not well suited for use with a commercial solid-state NMR probe with a round coil. Therefore, a homebuilt solid-state NMR probe was built and used with a stack of thin glass plates wherein the RF coil was wrapped directly around the flat square sample. Recently, we began to use magnetically aligned bicelles that are suitable for the structure determination of membrane proteins by solid-state NMR spectroscopy without any effort to build a flat square coil probe. These bicelle samples are well suited for use with a commercial solidstate NMR probe with a round coil, are very easy to prepare and are very stable, so that they can be kept for more than a year. In this paper, we present the solid-state NMR spectra of optimized and magnetically oriented bicelle samples of membrane proteins.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.754-760
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• 2008

In this paper, we introduce an RFID planar coil whose inductance does not change when it is attached on the metal surface. The coil is designed considering the inductance reduction on metal surface so that the inductance is the inverse times the reduction rate, and copper pour is placed in the bottom layer of the coil. This coil configuration is very simple and effective in constructing RFID systems for managing objects with metal surface because it prevents inductance reduction on metal surface.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1268-1277
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• 2018

A relatively high operating frequency is required for efficient wireless power transfer (WPT). However, the alternating current (AC) resistance of coils increases sharply with operating frequency, which possibly degrades overall efficiency. Hence, the evaluation of coil AC resistance is critical in selecting operating frequency to achieve good efficiency. For a Litz wire coil, AC resistance is attributed to the magnetic field, which leads to the skin effect, the proximity effect, and the corresponding conductive resistance and inductive resistance in the coil. A numerical calculation method based on the Biot-Savart law is proposed to calculate magnetic field strength over strands in Litz wire planar spiral coils to evaluate their AC resistance. An optimized frequency can be found to achieve the maximum efficiency of a WPT system based on the predicted resistance. Sample coils are manufactured to verify the resistance analysis method. A prototype WPT system is set up to conduct the experiments. The experiments show that the proposed method can accurately predict the AC resistance of Litz wire planar spiral coils and the optimized operating frequency for maximum efficiency.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1446-1454
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• 1990

A systematic method of design modification to reduce the influence of impact from multiple clearances in a planar four bar mechanism is developed. For this purpose, an optimization method is used with the objective function which is the linear sum of the Earles and Wu criteria for every joints with clearances. One coil spring is attached to a joint of limited range of revolution to reduce the undesirable dynamic effects due to clearances at joints. The stiffness of the coil spring and its pre-loading angle are chosen as design variables. A numerical example is taken for a four bar mechanism. The initial and modified mechanisms are compared using a clearance mechanism analysis technic to see the difference in dynamic effects due to contact loss. It is found that the modified mechanism produces much more smooth joint contact forces than the original design.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.119-126
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• 2016

In this paper, we proposed the planar textile resonator for constructing wearable MR-WPT system and analyzed the characteristic of textile substrates used in resonators. The planar textile resonators were designed to resonate at 1-10 MHz. The loop and coil were fabricated planar structure on textile substrate using conductive materials. Polyester fiber and cotton widely used in real life were chosen as textile resonators for wearable applications and copper tape and silver paste were used for fabricating planar loop and coil on textile substrate. For comparison analysis on transfer efficiency according to the types of textile, transmitter and receiver parts were symmetric. According to the result, for the highest transfer efficiency of wearable WPT system, the planar resonators have specifications of relative thick textile substrate with low permittivity and low surface resistance of conductive pattern. The performed experiments show that the planar textile resonator is possible to be used for resonator in wearable MR-WPT system.

• Journal of the Korean Magnetics Society
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• v.14 no.6
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• pp.232-235
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• 2004

Linear GMR isolator which is profitable for transmitting analog signal was modeled and the output voltage and current in relation to the input current were investigated. GMR isolator modeling was divided into two parts, namely magnetic and electric parts. The flow chart of the modeling was drawn in which the MR curve of the spin valves were incorporated to obtain the electrical voltage output. For magnetic modeling, 3-dimensional model of planar coil was analyzed by FEM method to obtain the magnetic field strength corresponding to the input current. Coil efficiency of the planar coil having magnetic core layer was shown to have about 1.5 times larger than that of the coil without the magnetic core layer. The feedback coil current(output current) corresponding to the input coil current was calculated to be within ${\pm}$0.25 mA of the linear fitting function of I$\_$out/= I$\_$in/-5 mA. Also, the response time and output waveforms were obtained when the coil current was a rectangular waveform. The rise time and fall time was 6 ${\mu}\textrm{s}$, respectively when the slew rate of the op-amp was 0.3 V/${\mu}\textrm{s}$.