• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.309-313
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• 2001

In this paper, a multifunctional three-phase electronic step-down transformer with output voltage stabilization characteristics is presented for custom power applications. The proposed electronic transformer has some advantages and features as follows: 1) It has 40 % weights lighter than that of commercial magnetic transformer, 2) It has output voltage stabilization characteristic with regulated output voltage over input variations, 3) It cab be operated as circuit breaker in the case of emergency, 4) It can be operated with so called soft starting function. Moreover, the electronic transformer may have stand-by power cutoff function and act as distortion compensator. This paper show the circuit diagram and present its features through various PSPICE simulations.

• Journal of Magnetics
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• v.21 no.2
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• pp.235-238
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• 2016

Microstructure and magnetization behaviors of $MnBi/Fe_3B/Nd2_Fe_{14}B$ nanocomposite alloy have been investigated. It was found that the coercivity increased firstly and then decreased, and saturation magnetization decreased with the additon of MnBi alloy. The addition of 40 wt.% MnBi powder enhanced the coercivity from 192.8 kA/m to 311.2 kA/m. The ${\delta}M$ and D(H)-H plots suggested the occurrence of a stronger exchange-coupling occurring between the hard and soft magnetic phase for this sample. The dependence of coercivity with temperature was discussed in 40 wt.% $Mn_{55}Bi_{45}$/ 60 wt.% $Nd_{4.5}Fe_{76.5}Nb_{0.5}B_{18.5}$ alloy powder, and a positive temperature coefficient was founded from 298 K to 350 K.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.35.2-35.2
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• 2011

We have investigated a coronal jet near the limb on 2010 June 27 by Hinode/X-Ray Telescope (XRT), EUV Imaging Spectrograph (EIS), SDO/Atmospheric Imaging Assembly (AIA), and STEREO. From EUV (AIA and EIS) and soft X-ray (XRT) images we identify the erupting jet feature in cool and hot temperatures. Using the high temporal and multi wavelength AIA images, we found that the hot jet preceded its associated cool jet and their structures are well consistent with the numerical simulation of the emerging flux-reconnection model. From the spectroscopic analysis, we found that the jet structure changes from blue shift to red one with time, which may indicate the helical structure of the jet. The STEREO observation, which enables us to observe this jet on the disk, shows that there was a dim loop associated with the jet. On the other hand, we found that the structure of its associated active region seen in STEREO is similar to that in AIA observed 5 days before. Based on this fact, we compared the jet morphology on the limb with the magnectic fields extrapolated from a HMI vector magnetogram of this active region observed on the disk. Interestingly, the comparison shows that the open and closed magnetic field configuration correspond to the jet and the dim loop, respectively, as the Shibata's jet model predicted.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2206-2208
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• 2003

LMTT(Linear Motor-based Transfer Technology) is horizontal transfer system in the maritime container terminal for the port automation. The system is modeled PMLSM(Permanent Magnetic Linear Synchronous Motor) that is consists of stator modules on the rail and shuttle car(mover). Because of large variant of movers weight by loading and unloading containers, the difference of each characteristic of stator modules, and a stator module's default etc., LMCS(Linear Motor Conveyance System) is considered as that the system is changed its model suddenly and variously. In this paper, we will introduce the soft-computing method of a multi-step prediction control for LMCS using DR-FNN(Dynamically Constructed Recurrent Fuzzy Neural Network). The proposed control system is used two networks for multi-step prediction. Consequently, the system has an ability to adapt for external disturbance, cogging force, force ripple, and sudden changes of itself.

• Journal of Powder Materials
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• v.14 no.4
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• pp.261-264
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• 2007

The electromagnetic wave (EM) absorption properties of various particle size have been investigated in a sheet-type absorber using the $Fe_{73}Si_{16}B_{7}Nb_{3}Cu_{1}$ alloy powder. With decreasing the average particle size, the complex permeability (${\mu}_{r}$) and permittivity (${\varepsilon}_{r}$) increased and the matching frequency is shifted toward lower frequency. The fabricated EM wave absorbers showed permeability $2{\sim}6$, permittivity $17{\sim}23$ for a $-325{\sim}+400$ mesh sample, and the calculated power absorption was as high as 80% in the frequency range over 2 GHz.

• The Korean Journal of Pain
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• v.18 no.1
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• pp.34-38
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• 2005

Background: Over the years, disc surgery has progressively evolved in the direction of decreasing trauma and its invasiveness. Conventional open surgery has many complications, such as scarring, instability, bleeding and a relative high mortality rate. Minimally invasive spinal surgery is now an alternative to a traditional discectomy. Herein, we present an operative technique, and the early results, for a percutaneous endoscopic lumbar discectomy in herniated lumbar disc disease. Methods: 43 patients, including 27 men and 16 women, with ages ranging from 18 to 66 years, were enrolled in this study. All the patients showed a protruded or extruded soft disc herniation at the lumbar level on magnetic resonance imaging and computed tomography. A percutaneous endoscopic lumbar discectomy was applied to the patients, and clinical responses evaluated using MacNab's criteria. Results: 40 patients were regarded as showing successful responses (93.1%), and there were no severe complications, such as a hematoma, nerve injury, postoperative dysesthesia or death. One patient underwent fusion surgery for remnant back pain six month later. Conclusions: We conclude that, in properly selected patients, a percutaneous endoscopic lumbar discectomy is a safe, noninvasive and effective treatment modality for herniated lumbar intervertebral disc disease.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.57-63
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• 2012

A surfaced permanent magnet spherical motor is capable of operating as three degree of freedom that used for the joints of the robot's arm, leg, and eyes. Ongoing research like new concept is essential part of motor field, it will make a great contribution in the future the overall portion of the motor, is becoming expected. The author analysis torque characteristics in spherical motor with state of rotating and positioning. And future design direction is smaller motors with equivalent or higher output. Solutions as torque and efficiency improvements are selecting the core with special processing type like powder metallurgy materials. Their special characteristic is high permeability and low eddy current losses at high speed, so improved the torque and efficiency.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1029-1030
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• 2007

This paper describes the dynamic analysis method and the characteristics of rotating type transverse flux motors excited by permanent magnets; the machine is called TFRM in here. A prototype of TFRM, made by combing soft magnetic composite (SMC) core, is introduced first, then the magneto static and dynamic analysis methods are explained. Analysis results are compared with measured results, and finally the effects of the proposed dynamic analysis method and the characteristics of TFRM are discussed.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.144-148
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• 2001

We report a rare case of Brown-Sequard syndrome associated with Horner's syndrome in cervical epidural hematoma caused by a ruptured arteriovenous malformation. A 54-year-old man developed sudden sharp neck pain, radiating to the interscapular area. Within hours, left side hemiplegia and decreased tactile sense and loss of contralateral pain sense ensued. Emergency cervical magnetic resonance image showed an epidural hematoma over the cervico-thoracic junction. The hematoma was located in the left posterolateral area of the cervical spinal canal. Emergent decompressive laminectomy and an evacuation of the hematoma were performed. A tangled soft tissue mass found in the hematoma was proven to be an arteriovenous malformation. To the authors, knowledge, this might be the first case of a Brown-Sequard syndrome associated with Horner's syndrome caused by ruptured cervical epidural arteriovenous malformation.

• Journal of Korean Neurosurgical Society
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• v.29 no.3
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• pp.396-401
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• 2000

We report a case of spontaneous cervical epidural hematoma caused by a pure epidural arteriovenous malformation. A 22-year-old woman developed a sudden quadriplegia after a vigourous physical therapy including multiple acupunctures for her neck pain. Emergency cervical magnetic resonance image showed an epidural hematoma in her cervicothoracic junction. Emergent decompressive laminectomy and an evacuation of the hematoma were performed. A soft tissue mass found in the hematoma was proven to be an arteriovenous malformation. Postoperatively, the patient experienced some complications. However, she recovered completely from the motor weakness.