• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.66-68
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• 2005

This paper presents the reduction characteristics of penetrated electromagnetic fields through a narrow slot aperture in a planar conducting screen of infinite extent. When a plane wave is excited to the narrow slot, the aperture electric field is controlled by the parallel plate connected on the slot. The magnitude of penetrated electromagnetic fields through a narrow slot is controlled by electric field distributions on the slot aperture. An integral equation for the aperture electric field on narrow slots is derived and solved by applying Galerkin's method of moments. The results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by installing the parallel plate on the slot aperture.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.586-594
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• 2013

This paper proposes a new coupling element of microwave slot coupler for designing waveguide slot array which can reduce the effect of undesired higher order mode coupling between coupling and radiating slots in the branch waveguide. The proposed device is composed of a centered longitudinal shunt-series coupling slot at the center of broad wall shared by two crossed rectangular waveguides and an asymmetric compound iris that excites the coupling slot. We first have obtained scattering parameters for the proposed coupler by use of EM S/W tool HFSS and then extracted the parameters of T- network equivalent circuit for the coupling slot. We also have analyzed the resonant properties such as resonant length and normalized admittance by changing the geometrical dimensions. The measured results for the fabricated coupler with short-circuited block ${\lambda}_g/4$ away from the coupling slot are well agreed with the simulated ones.

• The korean journal of orthodontics
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• v.45 no.1
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• pp.29-37
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• 2015

Objective: The coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined. Methods: Four types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a $0.017{\times}0.025$-in wire in the 0.018-in slots and a $0.019{\times}0.025$-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukey's post-hoc test at the 95% confidence level (${\alpha}$ = 0.05) were also used for statistical analyses. Results: There were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (${\mu}$ = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (${\mu}$ = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (${\mu}$ = 0.85). Conclusions: Brackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases.

• The Journal of the Korea Contents Association
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• v.7 no.7
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• pp.24-30
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• 2007

This paper observed characteristics of a triangular microstrip patch antenna with T-slot. When a narrow horizontal slot or vertical slot is embedded in a triangular microstrip antenna, we investigated variations of dual resonant frequency according to slot lengths and then we could make a triangular microstrip antenna with T-type slot suitable to a very low dielectric substrate. The proposed antennas used a dielectric substrate which has relative dielectric constant ${\epsilon}_r=3.38$ and a height of 8 [mils] (=0.2032mm) and antenna characteristics of horizontal or vertical slot antennas are compared by a ensemble 8.0 simulator. Theoretical and experimental results of manufactured antennas are compared.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.433-436
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• 2005

This paper presents the reduction methods of penetrated electromagnetic fields through a narrow slot aperture in a planar conducting screen of infinite extent. When a plane wave is excited to the narrow slot, the aperture electric field is controlled by the resistive sheets loaded on the slot. The magnitude of penetrated electromagnetic fields through a narrow slot is controlled by electric field distributions on the slot aperture. The results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by the resistive sheets on the slot aperture.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.214-217
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• 2007

This paper presents a reduction method of penetrated electromagnetic fields through a narrow slot with resistive sheet in a planar conducting screen of infinite extent. When a plane wave is excited to the narrow slot, the aperture electric field is controlled by the parallel plates connected on the slot. The magnitude of penetrated electromagnetic fields through the narrow slot is controlled by the electric field distribution on the slot. The results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by installing the resistive plates on the slot.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.107-110
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• 2005

This paper presents the reduction methods of penetrated electromagnetic fields through a narrow slot aperture in a planar conducting screen of infinite extent. When a plane wave is excited to the narrow slot, the aperture electric field is controlled by the resistive sheets loading on the slot. The magnitude of the penetrated electromagnetic fields through a narrow slot is controlled by electric field distributions on the slot aperture. The results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by the resistive sheets on the slot aperture.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.59-65
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• 2000

This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value Problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.281-283
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• 2006

This paper presents the reduction methods of penetrated electromagnetic fields through a narrow slot aperture in a planar conducting screen of infinite extent. When a plane wave is excited to the narrow slot, the aperture electric field is controlled by the resistive sheets loading on the slot. The magnitude of the penetrated electromagnetic fields through a narrow slot is controlled by electric field distributions on the slot aperture. The results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by the resistive sheets on the slot aperture.

• ETRI Journal
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• v.23 no.1
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• pp.33-38
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• 2001

A numerical simulation and an experimental implementation of T-shaped microstrip-fed printed slot array antenna are presented in this paper. The proposed antenna with relative permittivity 4.3 and thickness 1.0mm is analyzed by the finite-difference time-domain (FDTD) method. The dependence of design parameters on the bandwidth characteristics is investigated. The measured bandwidth of twin-slot array antenna is from 1.37 GHz to 2.388 GHz, which is approximately 53.9 % for return loss less than or equal to -10 dB. The bandwidth of twin-slot is about 1.06 % larger than that of single-slot antenna. The measured results are in good agreement with the FDTD results.