• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.397-401
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• 2005

In this paper, a slot-coupled microstrip antenna with switchable polarization is proposed for the polarization diversity applications in the complicated communication environment. The proposed antenna is fed by a microstrip line through one of two slots located with the interval of $\lambda{g}/4$ in the ground plane. By switching the PIN diode between opened and shorted termination which is located at the tip of the microstrip line, the switching function between horizontal and vertical polarization was confirmed experimentally. The measured resonant frequencies of the fabricated antenna are $2.41\;\cal{GHz}\;2.40\;\cal{GHz}$ and the cross polarization levels are $19\;\cal{dB},\;23\;\cal{dB},\;the\;-10\;\cal{dB}$ return loss bandwidths are $95\;\cal{MHz}\;100\;\cal{MHz}$ in horizontal and vertical polarization, respectively, and the antenna gain is almost $6\;\cal{dBi}$.

• Steel and Composite Structures
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• v.35 no.5
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• pp.701-715
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• 2020

Steel storage racks are lightweight structures, made of thin-walled cold-formed members, whose behaviour is remarkably influenced by local, distortional and overall buckling phenomena, frequently mutually combined. In addition, the need of an easy and rapid erection and reconfiguration of the skeleton frame usually entails the presence of regular perforations along the length of the vertical elements (uprights). Holes and slots strongly influence their behaviour, whose prediction is however of paramount importance to guarantee an efficient design and a safe use of racks. This paper focuses on the behaviour of isolated uprights subjected to both axial load and bending moments, differing for the cross-section geometry and for the regular perforation systems. According to the European standards for routine design, four alternatives to evaluate the bending moment-axial load resisting domains are shortly discussed and critically compared in terms of member load carrying capacity.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.62-67
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• 2007

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin (Au/Sn) eutectic solder bonding. The membrane chip has 2.5 mm${\times}$2.5 mm, $0.5{\mu}m$ thick low stress silicon nitride membrane, 2 mm${\times}$2 mm Au/Ni/Cr membrane electrode, and $3{\mu}m$ thick Au/Sn layer. The backplate chip has 2 mm${\times}$2 mm, $150{\mu}m$ thick single crystal silicon rigid backplate, 1.8 mm${\times}$1.8 mm backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50-60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is $39.8{\mu}V/Pa$ (-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.11
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• pp.578-584
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• 2013

Vertical open display cases are widely used in shopping malls, supermarkets, or retail stores to sell frozen and refrigerated products. Open display cases use air curtains to maintain a reasonable temperature within the storage space, prevent insects from breaking in, and reduce energy usage. In this research, computational fluid dynamics was used to find the optimal condition for reducing energy by considering various conditions such as discharge speed or temperature of air curtains. Results of the study showed that the amount of energy consumed in the display cabinet is influenced by the discharge speed and temperature of the slots installed on the upper area and the amount of air supplied to the storage area inside the shelf. This shows that the amount of discharged air supplied from the storage area influences the formation of air curtain and also the amount of energy consumption. As a result of this study, we learned that the amount of energy used can be reduced by increasing the amount of discharged air within the storage area and enhancing back pressure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.59-60
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• 2018

In this paper, we studied a design method for a band-pass waveguide filter with a modified H-type resonant iris (RI) placed in a thin transverse wall of a rectangular waveguide. The horizontal straight gap at the center of a conventional H-shaped iris is modified to a U-shaped one to increase the equivalent capacitance, and the equivalent inductance is improved by changing the vertical two straight slots into C-shaped ones. A third-order band pass filter using the proposed modified H-shaped iris was designed and, it was observed that the filter operated in the frequency range of 9.22-9.75 GHz with its insertion loss of 0.5 dB and return loss of 17 dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.509-516
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• 1999

In this paper, it is designed a microstrip U-slotted patch antenna with double resonances to enhance the bandwidth. In the design of an U-slotted patch antenna, there are considered the input impedance, the width of patch, the total length of the slot, the height of foam, the position of the probe and the radius of feed pin. The broadband behavior of antenna can be obtained by adjusting the length and width of the slot. The radiation from the antenna is linear polarized with the E-paine parallel to the vertical slots and the H plane parallel to horizontal slot. The radiation pattern, impedance locus, and VSWR of the antenna are calculated using "ENSEMBLE" software, and compared with the experimental results. Experimental results show that the bandwidth for VSWR $\le$ 2:1 is about 28.6%, a directivity 14.18dBi at 6.040GHz. 6.040GHz.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.3
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• pp.101-109
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• 2012

Because the installation problem of parabola antenna that is tilted to 45 degree when this antenna is installed at the area of middle latitude, the study on planar antenna in place of parabola antenna is made rapid progess. Especially, The development of the planar antenna for VSAT is needed depending on the increased Ka-band satellite communications. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. Especially, for the lower sidelobe level, the design method of the radiation power distribution control using the different slot widths is proposed. An array antenna consisting of 32 leakywave waveguide antennas is showing 35.16 dBi of gain, 2.5 degree of beamwidth at azimuth, below than -30 dB of sidelobe level, 45.8 degree of beam tilt angle in center frequency 30.2 GHz.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.69-77
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• 2009

Small size and low profile antenna for mobile vehicular-top-mounted is needed in satellite communication services such as DBS, Satellite Internet and VSAT. In middle latitudes, the development of an array antenna which has the conformal, low profile and 45 degree beam tilted configuration, and has the high gain with sharp beamwidth, low sidelobe and low loss is required for Ka band satellite communication. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. Especially, for the lower sidelobe level the radiation power control using a design method of the different slot width is proposed. An array antenna consisting of 32 leakywave elements is showing 34.4 dBi of gain, 3.6 degree of beamwidth, below than -25 dB of sidelobe level, 43 degree of beam tilt angle in center frequency 20.0 GHz. Feed network designed by waveguide cooperated feed shows good performance of wideband and low loss.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1195-1204
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• 2021

In this paper, we present an optimal design method for wave power generators using the response surface analysis. Especially, in our method, we reduce the mechanical loss by selecting the linear generator whose linear movement can be converted to the electrical energy directly with the vertical movement of waves. Therefore, we calculate the exciting force acting on the drive device in a slow-wave condition and determine the winding process with a ratio of the slots and poles for the improvement of energy conversion efficiency. In addition, we employ the regression analysis for deriving the shape factors of the stator and the translator, which have a significant effect on the performance of a generator. We choose the best design variables through the response surface analysis, and then we study the optimization method for designing the efficient experiment using the analysis results. Finally, we show the validity of the proposed method through the simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.347-353
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• 2018

In this paper, we studied a design method for a band-pass waveguide filter with a modified H-type resonant iris (RI) placed in a thin transverse wall of a rectangular waveguide. The horizontal straight gap at the center of a conventional H-shaped iris is modified to a U-shaped one to increase the equivalent capacitance, and the equivalent inductance is improved by changing the vertical two straight slots into C-shaped ones. From some simulation results for the frequency response of the proposed RI, it was observed that the proposed iris was advantageous for reducing its size and having better cutoff, compared to typical H-shaped one. Equivalent inductance, capacitance, and quality factor of the proposed RI were extracted to analyze its performance. A third-order band pass filter using the proposed modified H-shaped iris was designed and, it was observed that the filter operated in the frequency range of 9.18-9.84 GHz with its insertion loss of 0.3 dB and return loss of 14 dB.