• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.131-137
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• 2000

2 phase 8 pole HB-type(flat-type) Linear Pulse Motor can be used as the high precision position actuator because of its many advantages (simple control circuit, high stiffness characteristics, etc). Also, using the microstep drive, its noise and vibration can be reduced considerably and positional resolution may be increased further. But, $20^{\circ}$tapered tooth shape to reduce the normal force have an much effect on the static thrust force characteristics. And, because of hybrid-type LPM, interaction between the permanent magnet and the excitation current have an effect on the various characteristics of LPM. Hence, in this paper, the effect of tooth shape on static thrust force characteristics was analyzed using the air gap permeance by finite element method. For analyzing the effect of unbalance between the m.m.f of permanent magnet and the m.m.f of excitation current, unbalanced m.m.f coefficient $\sigma$ were introduced with the permenace matrix and switching matrix.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.125-135
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• 2001

A 8$\times$4 microstrip antenna array is designed at 5.3 GHz and its characteristics are investigated with respect to the application in dual polarized synthetic aperture radars. The design is focused on the achievement of a wide bandwidth, a high polarization purity, a low loss, a good isolation and some mechanical requirements suitable for the application. The antenna is fed by a -3 dB tapered feed network, and is composed of dual polarized SSFIP (Strip-Slot-Foam-Inverted Patch) elements with honeycomb and shielding plane. Simulation results for the antenna array are presented and compared with measurements. It is observed that the antenna shows a bandwidth of 80 MHz, a polarization isolation better than 20 dB, an isolation of 40 dB, and good mechanical characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.53-59
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• 2002

In this paper, we present design results for an orthomode transducer(OMT) to be used in multi-band antenna feeds. The OMT is realized in the form of a tapered square waveguide, where 18-20 GHz ports are placed in the taper region normal to the waveguide axis, while 30-45 GHz ports are placed in line with the waveguide axis. The reflection coefficient of each port is designed to be less than 20 dB, while the isolation between ports are greater than 15 dB. Thin septa are placed in side ports to reduce the effect of side ports on the return loss of the in-line port. The commercial software HFSS？ is used to design the whole structure.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.108-116
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• 2018

In this paper, a method of designing a Vivaldi type phased array antenna (PAA) which operates at S-band (2.8-3.3 GHz) is presented. The presented antenna uses broadside coupled split ring resonators (BC-SRRs) for high isolation, wide field of view, and good active S-parameter characteristics. As an example, we design a $1{\times}8$ array antenna with various BC-SRR structures using theory and EM simulations. The antenna is fabricated and measured to verify the design. With the BC-SRR implemented between the two radiating elements, the isolation is shown to be enhanced by 6 dB, up to 23 dB. The scan angle is shown to be within ${\pm}53^{\circ}$ based on a -10 dB active reflection coefficient. The operation of the scan angle is possible within ${\pm}60^{\circ}$ with a little larger reflection coefficient (-7 dB to -8 dB). The proposed design with BC-SRRs is expected to be useful for PAA applications.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1159-1163
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• 2012

In this paper, a new method is suggested to reduce the size of a wide-band array antenna. The power-divider for the feeding structure is made compact as ${\lambda}/8$ with the help of a novel Metamaterial UWB bandpass filter. This power divider is clearly different from others in that the proposed design uses microstrip structured Composite Right and Left-Handed (CRLH) filters, while others use two dielectric layers or long tapered transmission lines. In order to validate the proposed design method, the circuit and full-wave simulated results of the power divider with the Metamaterial UWB filters are compared to each other, and the Metamaterial properties of the structure are shown with the electric field at the ZOR and dispersion diagram. Furthermore, the antenna performance of the fabricated antenna with the power divider is measured and compared with the prediction. Also, the size reduction effect by the proposed scheme is addressed.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.16-22
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• 2014

Automotive NVH on brake operation is mainly caused by a coupling action of vehicle speed and inter parts friction and its frequency occurs over a broad band of 0.1 kHz~10 kHz. Especially, squeal noise, being a self-excited vibration generated by friction force between drum and lining, occurs over 1 kHz and consequently dynamic instability is induced when friction energy is applied to a brake vibration system. The squeal strongly depends on nonlinear properties influenced by the material of lining, velocity of vehicle, and the dynamic properties of a brake system. The dynamic properties are considered as a main influential design factor to squeal noise, however the analysis of the properties are rarely facilitated due to arbitrariness of shape by wearing down. In this paper, we research generating tendency of squeal noise through complex eigenvalue analysis, tracking drum brake's unstable modes in accordance with the wear shape of drum and lining such as tapered and bellmouth shape, and analyze computed unstable modes by variable shapes.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.677-681
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• 2014

A high voltage pulse generator was fabricated to radiate ultrawide band electromagnetic pulse. A coaxial type of Blumlein pulse forming line is employed to produce a pulse of high voltage (>300 kV) and short pulse duration (~5 ns). A helical strip/wire type of air-cored pulse transformer was used to charge the Blumlein pulse forming line up to more than 300 kV. A peaking switch is essential to make the pulse rise time as fast as possible. Typically, the rise time is ~500 ps. The output pulse of the generator is radiated into air through an exponentially tapered TEM horn antenna. The electric field intensity of a radiated pulse was measured as a function of the distance from the transmitting horn as well as the output voltage of the peaking switch. The peak-to-peak value of the electric field intensity at 10 m from the TEM antenna was~100 kV/m.

• Mycobiology
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• v.44 no.4
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• pp.191-201
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• 2016

In this study, the phylogeny and morphology of Mycosphaerella nawae (Dothideomycetes, Ascomycota) were examined using Korean and Japanese isolates, to establish the phylogenetic relationship between M. nawae and its allied species. Korean and Japanese isolates of M. nawae were collected from circular leaf spot-diseased leaves and were confirmed based on internal transcribed spacer (ITS) sequence data. Phylogenetic analysis was conducted using multiple genes, including the ITS region, 28S rDNA, ${\beta}-tubulin$, translation elongation $factor-1{\alpha}$, and actin genes. Our results revealed that M. nawae is closely related to members of the genus Phaeophleospora but are distant from the Ramularia spp. In addition, microscopic analysis revealed pseudothecia on the adaxial and abaxial surface of overwintered diseased leaves (ODL) and only on the abaxial surface of diseased leaves. Ascospores are oval to fusiform, one-septate, tapered at both ends, $1.7{\sim}3.1{\times}8.1{\sim}14.1{\mu}m$, and were observed in ODL. Conidia are oval, guttulate, one-septate, $3.5{\sim}4.9{\times}12.8{\sim}19.8{\mu}m$, and barely discernable on 30-day cultures. To our knowledge, this is the first report on the phylogeny of M. nawae, which is closely related to the genus Phaeophleospora, especially P. scytalidii.

• Journal of Veterinary Clinics
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• v.32 no.6
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• pp.523-526
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• 2015

A 9-year-old, castrated male Malamute dog was presented with chronic cough. On thoracic computed tomography, non-tapered and dilated peripheral bronchi were detected. Bronchoarterial ratio was about 2.2. The dilated bronchi appeared as a cluster of grapes especially in left cranial, left caudal and right middle lung lobe. Based on the computed tomographic findings, the diagnosis was made as the saccular type of bronchiectasis.

• Journal of Veterinary Clinics
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• v.34 no.2
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• pp.103-107
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• 2017

A 7-year-old spayed female Shih-tzu dog with 4-month history of anorexia and weight loss was diagnosed with splenic hemangiosarcoma. One week after splenectomy, the dog developed severe, multifocal, coalescing erosive and ulcerative dermatosis with epidermal collarettes and crusts on the dorsal trunk. The dog was prescribed systemic antibiotics comprising cephradine and enrofloxacin postoperatively. Histopathological examination of skin biopsies from haired skin lesions revealed changes consistent with pemphigus foliaceus (PF). Tentative diagnosis for this patient was pemphigus-like drug reaction resulting from cephradine treatment. However, given the dog's history of hemangiosarcoma, paraneoplastic pemphigus (PNP), a rarely reported cancer-related pemphigus in dogs, was also considered for tentative diagnosis. Significant clinical remission of dermal lesions was achieved with four weeks of prednisolone and mycophenolate mofetil (MMF) treatment. Drugs were gradually tapered and eventually discontinued with concurrent reduction of dermal lesions, and no further recurrence was noted.