• Journal of Biomedical Engineering Research
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• v.13 no.1
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• pp.25-32
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• 1992

A new restoration method of chest X -ray image (dual project filter) was proposed to improve SNR(signal to noise ratio) characteristics. In this method, a priori Information of system and anatomical structure and statistics of projected object are used in the design of filter. Dual projection filter varies its parameters, adapting to the local regions of chest(lung region, mediasternum, subdiaphragm) and the structure of chest (bone, tissue, blood vessel, bronchia). The performance of Dual Projection Filter was 0.1-0.2dB better than Dual Sensor Wiener Filter, which was used for initial estimate of Dual Porjection Filter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.37-43
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• 2007

In this.paper, we introduce design and implementation results of the single balanced diode mixer for European point-to-point microwave radio in order to improve flatness performance. When a resonator such as RF filter is integrated with a mixer, impedance characteristic of 50 ohm is maintained only in RF band, not in LO band resulting deterioration of flatness performance because of LO power variation on the diode. In the paper, we suggest a design method of mixer integrated with image rejection filter and LO harmonic filter to have a better performance of flatness using embedding electrical length between filter and mixer's port. Frequency specification of fabricated mixer is $21.2{\sim}22.6\;GHz$ for RF, $19.32{\sim}20.72\;GHz$ for LO and 1.88 GHz+/-50 MHz for IF, respectively. Measured results show conversion loss of 8.5 dB, flatness of 2 dB, input PldB of 8 dBm, IIP3 of 15 dBm under LO power level of 10 dBm. Return losses of RF, LO and IF port are under -12 dB, -10 dB and -5 dB, respectively. Isolations of LO/RF and LO/IF are 20 dB and 50 dB, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.487-493
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• 2001

In this paper, A new microstrip bandpass filter is proposed. The novelty of the proposed structures is to use a interdigital capacitor and embeded slot that are fanned on a patch resonator such that its insertion loss and size can be significantly reduced simultaneously. As a result, it is found that the resonant frequency of patch filter designed at 5 GHz is decreased to 1.8946 GHz and the insertion loss is reduced from -2.168 dB to -0.379 dB. This proposed filter has small size and low insertion loss in comparison with the conventional parallel edge coupled bandpass filter.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.3 s.8
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• pp.73-78
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• 2005

In this paper, a bandpass filter with excellent cut off characteristic due to transmission zero using bypass coupling capacitor and with superior harmonic characteristic by interdigital capacitor is suggested. The measurement results for SIR bandpass filter with bypass coupling capacitor and interdigital capacitor show that the insertion loss is less than 1.9 dB and the return loss is better than 15.4 dB with 4.2 % bandwidth at the center frequency of 5.78 GHz.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.10
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• pp.1-7
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• 1997

This paper proposes a new real-time 2-D convolver filter architecture wihtout using any multiplier. To meet the massive amount of computations for real-time image processing, several commercial 2-D convolver chips have many multipliers occupying large VLSI area. Te proposed architecture using only one shift-and-accumulator can reduce the chip size by more than 70% of commercial 2-D convolver filter chips and can meet the real-time image processing srequirement, i.e., the standard of CCIR601. In addition, the proposed chip can be used for not only 2-D image processing but also 1-D signal processing and has bood scalability for higher speed applications. We have simulated the architecture by using VHDL models and have performed logic synthesis. We used the samsung SOG cell library (KG60K) and verified completely function and timing simulations. The implemented filter chip consists of only 3,893 gates, operates at 125 MHz and can meet the real-time image processing requirement, that is, 720*480 pixels per frame and 30 frames per second (10.4 mpixels/second).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2374-2381
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• 2007

.We have studied to obtain the properly conditions about impedance matching of the SAW filter for the SPUDT type and the bidirectional transducer type later. And we have studied to obtain the SAW filter for the Slanted Finger Interdigital Transducer(SFIT), was formed on the Langasite substrate and was evaporated by Aluminum-Copper alloy and then we performed computer-simulated by simulator In case the SPUDT, we have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflector are $5000{\AA}$ and $3.6{\mu}m$, respectively. And the of the bidirectional transducer, the width of IDT' fingers and the space between IDT' finger and reflector is $1.8{\mu}m$, respectively. Also, we have performed to series connected the SPUDT type with the bidirectional transducer type filter. The frequency response of the fabricated SAW filter has the property that the center frequency is about 190MHz and bahdwidth at the 3dB is probably 5.3MHz after when we have matched impedance. Also, we could obtain that ripple characteristics is less than 0.3dB and insert loss is probably -20dB after when we have matched impedance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.1-7
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• 2019

In this paper, we propose an approach to design a practical filter and a mathematical modeling for images. In the areas of signal processing, including high-dimensional image processing, the filtering process has been fundamental and crucial in diverse practical applications such as image processing, computer vision, and pattern recognition. In general, the ideal filter is modeled as circular-shaped in the 2D frequency domain as the rectangular shape is ideal for the 1D frequency domain. This paper proposes an approach to modeling practical and efficient image filter in the 2D frequency domain. Instead of employing a circular-shaped filter, this study proposes a polygon-shaped filter inspired by the concept of a hexagon cellular system for frequency reuse in wireless communication systems. By employing the concept of frequency reuse, bandwidth efficiency is also achieved in the frequency domain. To substantiate the proposed approach, quantitative evaluation is performed using PSNR.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.598-601
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• 2004

A microstrip filter has been designed and fabricated in hairpin form on a GaAs substrate and its characteristics such as the insertion loss, return loss, and bandwidth have been investigated. The presented filter is realized with relatively small size, 4.5 by 3.6 mm. The insertion loss and return loss of the filter are 1.17 dB and 30 dB, respectively. The filter exhibits 3 dB-bandwidth of 350 MHz at the center frequency, 5.890 GHz. The experimental results show good agreement with the numerical ones. However, the measured center frequency is about 100 MHz higher than the designed one.

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.415-420
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• 2007

In this paper, we have designed and fabricated a new type of bandpass-filter that used rectangular ring and interdigital capacitive feeding-structure. The filter is applied the modified rectangular ring and interdigital capacitive feeding-structure in patch, which reduce rho size of filter and IEEE 802. 11 correspond to wireless LAN domain(2.45GHz and 5.2GHz) for operating. As a result, the design and fabrication process of the filter become simple and the size of it is reduced more than 60% compared with RF filter are available conventional PEMBF(Parallel Edge-coupled Microstrip Bandpass Filter) of accounted circuit by minimum stage, measurement result of fabricated filter, center frequence is down 2.408GHz and 5.075GHz. input return loss is -39.169dB at 2.408GHz, -40.922dB at 5.075GHz. insertion loss is -0.437dB at 2.408GHz, -1.669dB at 5.075GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.38-42
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• 2010

In this paper, a design method of the compact narrow band filter on the microstrip board is proposed using slot-type split spiral resonators. The design technique of this filter is based on cascading filter stages consisting of the combination of slot-type split spiral resonators, capacitive gaps between patches, and inductive grounded stubs with the meander configuration. By these means, it was possible to get the nearly symmetric frequency responses, adjustable bandwidths, compact sizes. And also excellent characteristic of the out-of-band rejection is achieved in contrast to the conventional filter design technique. The measured insertion loss shows good results about -3.47dB at the center frequency($f_0$=1GHz) and passband return loss is less than -12.62dB. The 3dB fractional bandwidth(FBW) is approximately 7.3%. The results of the frequency response measured on the fabricated band pass filter substrate show satisfactory agreement with the simulated frequency responses by the MWS(Microwave Studio) of CST in the region of interest.