• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.85-87
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• 2001

Linear motor damper(LMD) for vibration control of structure is consisted of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure and an iron core as a pathway for magnetic flux. The active mass of LMD is 1.5 ton and consisted of permanent magnet and iron yoke. In this paper, LMD system is manufactured and tested for dynamic characteristics and frequency response.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.104-106
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• 2001

In this paper, it is object of design of high efficiency slotless BLDC motor using film coil. Slotless BLDC motor is able to have high efficiency property and low cogging torque, due to magnetization of stator core have constant contribution by slotless core. But it is difficult to make coil winding of slotless BLDC motor. So we make amateur of slotless BLDC motor using film coil. Film coil is fabricated by drilling, electro-plating and etching of copper/insulator/copper plate. In this paper, after design of slotless BLDC motor for moving axial blower, it is fabricated by NdFeB permanent magnet type rotor and film coil.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.404-407
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• 1995

Magnetic properties of model exchange-spring magnets, which are composed of magnetically soft and hard grains, were calculated by means of computer simulation. The dependence of the magnetic properties on the strength of intergrain exchange interaction and the amount of soft grains was studied. The existence of soft grains enhanced the remanence remarkably, and the remanence over $0.8M_{s}$ was obtained in the model magnets containing 25% or more soft grains by volume. The calculated coercivity vs. the strength of the exchange interaction curves showed a peak at a critical strength of the exchange interaction, although the remanence increased monotonously with increase in the strength of the exchange interaction. Thus the maximum energy product also reached a peak around the same critical strength. The calculated maximum energy product exceeded $300kJ/m^{3}$ when the magnet is assumed to be composed of $Fe_{3}B$ and $Nd_{2}Fe_{14}B$.

• 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.

• Resources Recycling
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• v.23 no.2
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• pp.3-16
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• 2014

Car exhaust $CO_2$ gas reduction and fuel efficiency of the car lighter for the current era is a big challenge. The developments of high-performance Nd magnets, Li-ion secondary battery and exhaust gas purification performance of PGM catalysts used in the lightweight EV and HEV are activated. Country in order to improve the car lighter and function that use the resources of rare metals are ubiquitous imported from China because of export supply control, as soaring prices have unstable supply and demand. Compared to the emissions from the next-generation automotive recycling, waste scarce resources need to be. This study investigated the recycling technology analysis and development of the information technology, or delivered to the researchers by giving national car industry aims to contribute to the development. Findings, pulmonary high-performance motor vehicle emissions in the exhaust gas purification PGM Catalysts, Li-ion battery and Nd magnets recycling technology, such as pre- and post-processing techniques to classify technology, pre-urban mining technology mechanical separation by screening techniques under development, the study and post-processing technology has, pyro and hydro metallurgical smelting technology is established. Waste Recycling in terms of economic efficiency of mechanical components for the intensive study of screening techniques is needed.

• Journal of the Korean Magnetics Society
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• v.13 no.4
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• pp.182-186
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• 2003

A new axial pressing method using pulse magnetizing field was studied to improve the remanence of Nd-Fe-B sintered magnets. In order to make near-net shape green compacts of butterfly, disk, or coin magnets, conventional axial-type pressing has been normally used. However, compared to the transverse-type pressing, it is not possible to obtain higher remanence by this method because the magnetic alignment of powder begins to deteriorate when the density of green compacts increases over a critical value. On the other hand, we found that an axial pressing under pulse magnetizing field was very effective to increase the degree of magnetic alignment of powder, yielding remanences even higher than those obtained by the transverse pressing. In this study, it was revealed that appropriate tapping density and how to apply pulse magnetic held were important to improve the grain alignment and thus remanence of Nd-Fe-B sintered magnet.

• The Journal of Advanced Prosthodontics
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• v.8 no.1
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• pp.9-15
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• 2016

PURPOSE. Although magnetic attachment is used frequently for overdenture, it is reported that attractive force can be decreased by abrasion and corrosion. The purpose of this study was to establish the clinical basis about considerations and long term prognosis of overdenture using magnetic attachments by investigating the change in attractive force of magnetic attachment applied to the patients. MATERIALS AND METHODS. Among the patients treated with overdenture using magnetic attachments in Dankook University Dental Hospital, attractive force records of 61 magnetic attachments of 20 subjects who re-visited from July 2013 to June 2014 were analyzed. Dental magnet tester (Aichi Micro Intelligent Co., Aichi, Japan) was used for measurement. The magnetic attachments used in this study were Magfit IP-B Flat, Magfit DX400, Magfit DX600 and Magfit DX800 (Aichi Steel Co., Aichi, Japan) filled with Neodymium (NdFeB), a rare-earth magnet. RESULTS. Reduction ratio of attractive force had no significant correlation with conditional variables to which attachments were applied, and was higher when the maintenance period was longer (P<.05, r=.361). Reduction ratio of attractive force was significantly higher in the subject group in which attachments were used over 9 years than within 9 years (P<.05). Furthermore, 16.39% of total magnetic attachments showed detachment of keeper or assembly. CONCLUSION. Attractive force of magnetic attachment is maintained regardless of conditional variables and reduction ratio increased as the maintenance period became longer. Further study on adhesive material, attachment method and design improvement to prevent detachment of magnetic attachment is needed.

• Journal of Society of Preventive Korean Medicine
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• v.3 no.1
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• pp.125-145
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• 1999

The effects of Wang-ttum, Magnetic Water, Magnetic field and Sibjeondaebotang on hemodynamics in sleep deprivation were studied. The results as follows; 1. In case of Wang-ttum operated group, significant changes were observed at 12 p.m., 2 a.m., 4 a.m. in maximum blood pressure for the first and second overnight stay and at 2 a.m. for the third and, respectively, average blood pressure at 12 p.m., 2 a.m. for the 1st and 2nd overnight stay, minimum blood pressure at 10 p.m.. 12 p.m.. 2 a.m. for the 1st overnight stay and at 10 p.m., 12 p.m. for the 2nd and at 12 p.m. for the 3rd, pulse rate at 12 p.m., 2 a.m., 4 a.m., 6 a.m., for 1st and 2nd and at 2 a.m., 4 a.m. for the 3rd and 4th, TP-KS at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and 2nd and at 2 a.m., 4 a.m., 6 a.m. for the 3rd, PRP at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and 2nd and at 12 p.m., 2 a.m., 4 a.m. for the 3rd and at 2 a.m., 4 a.m. for the 4th, TPR at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. from 1st to 4th overnight stay. 2. In case of taking magnetic water group, significant changes were observed at 2 a.m., 4 a.m. in pulse rate for the 1st overnight stay and, respectively, PRP at 2 a.m. for the 1st, TRP at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and 4th. 3. In case of attaching magnet group, TPR was significantly observed at 10 p.m. for the 1st overnight stay. 4. In case of medicating Sibjeondaebotang group, significant changes were observed at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. in maximum blood pressure for the 1st and 2nd overnight stay and at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 3rd and at 2 a.m., 4 a.m., 6 a.m. for the 4th and, respectively, average blood pressure at 10 p.m., 12 p.m. for the 1st and 2nd and at 10 p.m. for the 3rd and 4th, minimum blood pressure at 10 p.m., 12 p.m. from 1st to 4th, pulse rate at 2 a.m., 4 a.m., 6 a.m. from 1st to 3rd and at 2 a.m., 4 a.m. for the 4th, TP-KS at 10 p.m., 12 p.m., 2 a.m., 4a.m., 6 a.m. for the 1st and at 10 p.m., 2 a.m., 4 a.m., 6 a.m. for the 2nd and at 2 a.m., 4 a.m., 6 a.m. for the 3rd and at 6 a.m. for the 4th, PRP at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 2nd and 3rd and at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 4th, TPR at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. from 1st to 4th. As mentioned obove, the effects of Wangttum and Sibjeondaebotang on hemodynamics in sleep deprivation were observed both the impulse of SIM-YANG and mutual function of QI-HYOL. The effects of Magnetic water and Magnetic field were observed the side of mutual function of QI-HYOL.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.57-65
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• 2007

Along with the development of power electronics and magnetic materials, permanent magnet (PM) brushless direct current (BLDC) motors are now widely used in many fields of modern industry BLDC motors have many advantages such as high efficiency, large peak torque, easy control of speed, and reliable working characteristics. However, Compared with the other electric motors without a PM, BLDC motors with a PM have inherent cogging torque. It is often a principle source of vibration, noise and difficulty of control in BLDC motors. Cogging torque which is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance can be reduced by sinusoidal air-gap flux density waveform due to reduction of variation of magnetic reluctance. Therefore, this paper will present a design method of magnetizing system for reduction of cogging torque and low manufacturing cost of BLDC motor with isotropic bonded neodynium-iron-boron (Nd-Fe-B) magnets in ring type by sinusoidal air-gap flux density distribution. An analytical technique of magnetization makes use of two-dimensional finite element method (2-D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation. In addition, For optimum design of magnetizing fixture, Factorial design which is one of the design of experiments (DOE) is used.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.456-463
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• 2018

With the development of weapon systems by mounting various sensors, it makes important to analyze the precise functioning of sensor to external environment. In the case of small arms with magnetic sensor, the malfunction of small arms might be caused by strong external magnetic fields. In this study, the effects of magnetic sensor on external magnetic fields were analyzed, and optimal magnetic shield and shield structure were designed through M&S. In addition, the magnetic-shielding effectiveness of magnetic sensor in small arms was verified with commercial shielding materials. As a result, it was demonstrated that the Fe-Cu-Si-Nd-B with the structure of multi-layer metallic shields was shown the magnetic-shielding effectiveness of 83 % for an external permanent magnet and 19 % for an alternating magnetic field of 180 dBpT at 60 Hz, respectively.