• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.71-72
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• 2022

In this paper, the performance evaluation of the vibration damping ratio according to the polymer mixing ratio of the polymer modified mortar used as the floor finishing material of the apartment building structure was evaluated. To compare the vibration damping rate, ordinary potland cement (OPC) mortar and polymer modified mortar (PMM) were prepared. In addition, the mixed polymer was mixed with Styrene Butadiene Rubber (SBR) liquid polymer with a solid content of about 49%. Accordingly, the W/C of the test specimen was adjusted and compounded, and the experiment was conducted by mixing 5 types of the test specimen: OPC-60, PMM-5%, PMM-10%, PMM-15%, and PMM-20%. In addition, in order to adjust the W/C of the specimen, the fluidity of each specimen was set as 210 (±5) mm. The specimens measured density and flow in fresh mortar and after curing for 28 days, flexural strength, compressive strength and ultrasonic pulse were measured. The attenuation rate was shown. The experimental results showed that the density increased according to the mixing of the polymer, the flexural strength increased as the mixing rate of the polymer increased, and the compressive strength was decreased. In addition, it was shown that the vibration damping rate increases with the increase in the amount of polymer incorporated.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.5
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• pp.251-258
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• 2002

In this paper, the dipole-fed planar array antenna applied Yagi-Uda antenna away theory to microstrip antenna is designed and fabricated at X-band. The design procedure of the dipole-fed planar array antenna with the wide bandwidth is presented to be easily practiced to a wireless communication system. The radiation pattern, return loss and bandwidth of the antenna are improved by the finite differential time domain(FDTD) numerical method. The propriety of analysis of planar dipole antenna is proved from the measured data. From the measured results, the antenna maximum gain is 4.9dBi at center frequency of 10GHz and frequency bandwidth is about 40%. Front-to-back ratio is 16dB, and half-power beam-width of E-plane and H-plane are 117$^{\circ}$and 156$^{\circ}$, respectively. When VSWR of antenna is less than 2, the measured results are agreed well with the theoretical values in the frequency range from 7.4GHz to 11.88GHz.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.75-82
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• 2016

This study analytically reviewed the behavior of steel plate concrete (SC) walls subjected to forced vibration to investigate the effects of shape and arrangement spacing of studs on the behavior spacing of studs in SC wall were carried out. From the analyses, it was noted that the damping ratio obtained from the time history analyses showed overall high value in Half-power Bandwidth method and the lowest value in Fitted Exponential Curve method. And, in half of the design strength, the damping ratio presented approximately 3.0~4.2% and, in the design strength, it was approximately 4.1~5.2%. When the developed studs were used, the damping ratio was reduced slightly and it did not show consistent results between DS1 and DS2. When the distance between the studs increases more than necessary, it was also confirmed that the natural frequency was reduced and the damping ratio was increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3425-3430
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• 2013

The fast-growing market in wireless communications has led to the development of multi-standard mobile terminals. In this paper, a frequency-tunable active RC bandpass filter for multi-standards wireless communication system is designed using an active inductor. The conventional bandpass filter design methods employ the high order filter or high quality factor Q to improve the stopband attenuation characteristics and frequency selectivity of the passband. The proposed bandpass filter based on the high Q active inductor has an improved frequency characteristics. The center frequency and gain of the designed bandpass filter is tuned by employing the tuning circuit. We have performed the simulation using TSMC $0.18{\mu}m$ process parameter to analyze the characteristics of the designed active RC bandpass filter. The bandpass filter with Q=20.5 has 90MHz half power bandwidth at the center frequency of 1.86GHz. Moreover, the center frequency of the proposed bandpass filter can be tuned between 1.86~2.38GHz for the multi-standards wireless communication system using the capacitor of the tuning circuit.