• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.268-271
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• 2004

An analytic design formula is proposed for a TEM mode dielectric bandpass filter with attenuation poles at desired frequencies in the stop band. In order to sustain the constant ripple in the passband due to attenuation poles, the initial resonant frequencies of the various resonators adopted in a filter with attenuation poles are newly calculated. The proposed design theory is verified by designing various bandpass filters with attenuation poles in the stop band.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.80-88
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• 2016

For next generation global navigation satellite systems, new carrier frequencies in Ku/V band are expected to emerge as a promising alternative to the current frequency windows in L band as they get severely congestive. In the case of higher frequency bands, signal attenuation phenomenon through the atmosphere is significantly different from the L band signal propagation. In this paper, a fundamental investigation is carried out to explore the Ku/V band as a candidate frequency band for a new global satellite navigation carrier signal, wherein specific attention is given to the effects of the dominant attenuation factors through the tropospheric propagation path. For a specific application, a candidate orbit preliminarily designed for the Korean regional satellite navigation system is adapted. Simulation results summarize that the Ku band can provide a promising satellite navigation implementation considering the present satellite's power budget, while the V band still requires technical advances in satellite transceiver system implementations.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.356-363
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• 2006

The demand for digital multimedia service using Ka band satellite communication are growing rapidly. So, in this paper, we have analyzed rain attenuation with typical model, and proposed prediction model of rain attenuation in high frequency(20 GHz). This paper illustrates Korea rain attenuation characteristics at the Ka band Koreasat beacon frequency based on the theoretical and empirical approaches and seek for efficient techniques by rain attenuation estimate and analyzed performance of adaptive modulation system. Propose prediction model of rain attenuation and parameter of satellite link can be available for the Ka band satellite communication.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.387-392
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• 2006

In this paper, measurement scheme and uncertainty estimation of the K-band attenuation standard fitted with 3.5 mm coaxial connectors are described. The standard comprises a build-up chain of four steps of power ratio mea-surement and operates in the frequency range of 18 GHz to 26.5 GHz. The nominal attenuation of each step is around 20 dB and total dynamic range is 80 dB. The expanded uncertainty of the overall system is 0.01 dB at the confidence level of approximately 95%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1248-1256
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• 2015

It is necessary to apply an exact data and a precise prediction model for a rain attenuation to design the link margin for a data link using Ku-band with the serious effect by rain. In this paper, we investigate the regional rainfall-rate distribution of Korea proposed in TTAK.KO-06.0122/R1 and compare it with the distribution provided by Rec. ITU-R PN.837-1 and Crane. And, the rain rate climate regions similar with the rainfall-rate distribution of Korea in Rec. ITU-R PN.837-1 and Crane model are selected. Finally, using Rec. ITU-R P.618-8 and Crane rain attenuation prediction model, we derive and analyze the rain attenuation for Ku-band frequency according to the time percentage of an average year and the distance of wireless communication link between unmanned aerial vehicle (UAV) and ground data terminal (GDT).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.884-890
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• 2008

In this paper, Characteristics responded to frequency of a band-pass filter with admittance inverters(J-inverters) is considered. As a result, it is confirmed that attenuation characteristics of upper and lower frequency is asymmetric. And a modified circuit and design formulas are proposed to improve the asymmetric attenuation characteristics. By confirming the simulated and measured results that are got from designed and made a experiment on the band-pass filter with the proposed circuit and formulas for design, we confirm that the asymmetric attenuation characteristics of the band-pass filter are improved without any optimization or iterative design procedures and additional calculation efforts.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.751-755
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• 2003

In this paper, We proposed compact multi-layer LTCC (Low Temperature Cofired Ceramic) bandpass filter for Bluetooth module. A ${\lambda}/4$ coupled stripline resonators are designed, which composed of coupled strip-line section and loading capacitance. This resonator with a loading capacitor has slow-wave characteristics. Due to the slow-wave effect of the proposed resonator, it is possible to design and fabricate a compact bandpass filter with a wide upper stop band. Attenuation poles in the lower stop band are achieved using controlling of electro-magnetic coupling between resonators. Using multi-layer LTCC technology, we designed and fabricated band pass filter with a finite attenuation pole and wide upper stopband. The overall size of the filter is $1.2{\times}2.0{\times}1.0mm^3$.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.56-62
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• 2010

In this paper, a recurrent cerebellar modulation articulation control (RCMAC) has been developed for improvement of noise attenuation performance in active noise control system. For the narrow band noise, a filter-x least mean square (FXLMS) method has bee frequently employed as an algorithm for active noise control (ANC) and has a partial satisfactory noise attenuation performance. However, noise attenuation performance of an ANC system with FXLMS method is poor for broad band noise and nonlinear path since it has linear filtering structure. Thus, an ANC system using RCMAC is proposed to improve this problem. Some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source were executed. It is shown that satisfactory noise attenuation performance can be obtained.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.193-196
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• 2000

A new type low-pass filter design method based on a coupled line and transmission line theory is proposed to suppress harmonics by attenuation poles in the stop band. The design formula are derived using the equivalent circuit of a coupled transmission line. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range and low insertion loss. The seventh-order low-pass filter designed by present method has a cutoff frequency of 0.9 CHz with a 0.01 dB ripple level. The coupled line type low-pass filter with strip line configuration was fabricated by using a high-temperature superconducting (HTS : YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin film on MgO(100) substrate. Since the HTS coupled tine type low-pass filter was proposed with five attenuation poles in stop band such as 1.8, 2.5, 4, 5.5, 6.2 GHz. The fabricated low-pass filter has improved the attenuation characteristics up to seven times of the cutoff frequency.

• Structural Engineering and Mechanics
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• v.40 no.3
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• pp.373-392
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• 2011

Periodic and quasi-periodic Timoshenko beams on Pasternak foundation are investigated using the differential quadrature method. Not only band gaps in the beams but also the dynamic response of them is analyzed. Numerical results show that vibration in periodic beams can be dramatically attenuated when the exciting frequency falls into band gaps. Different from the band structures of periodic beams without foundation, the so-called critical frequency was found because of the Pasternak foundation. Its physical meaning was explained in detail and a useful formula was given to calculate the critical frequency. Additionally, a comprehensive parameter study is conducted to highlight the influence of foundation modulus on the band gaps.