• Journal of electromagnetic engineering and science
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• v.17 no.1
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• pp.34-38
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• 2017

In this paper, we propose an active tunable bandpass filter (BPF) for efficient spectrum sensing in the TV White Space (TVWS) band. By designing a narrow bandwidth, it is possible to improve the sensing probability. The basic circuit configuration involves switching the PIN diode compromising capacitor bank to change the capacitance of the LC resonant circuit. To cover the whole TVWS band effectively, we add a varactor diode, and the bandwidth is set to 25-MHz. We improve the insertion loss by using the active capacitance circuit. The tunable BPF in the TVWS band with a 20-MHz interval is designed to have 11 channels with a bandwidth of 25 MHz and a low insertion loss of 1.7-2.0 dB.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.12a
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• pp.68-77
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• 2003

TFT-LCD 모니터 및 TV의 핵심부품인 TFT/Color Filter를 제조하는 공장라인에서 제품의 품질에 중요한 역할을 하는 것은 유리기판에 TFT와 Color Filter을 형성시키는 노광공정(Exposure)이다. 이러한 TFT/Color Filter를 생산하는 공정내에서 노광기는 핵심기술이므로 진동에 대하여 엄격하게 관리되어지고 있다. 그리고, TV 및 TFT-LCD 모니터의 크기가 큰 것을 사용자의 요구로 TFT/Color Filter 생산 공장은 세대가 거듭될수록 사용되어지는 유리기판의 크기도 따라서 커지고 있다. 이러한 유리기판의 크기 증가는 공정라인에서 진동에 더욱더 취약해지는 결과를 초래하므로 보다 엄격하게 진동관리가 필요하게 된다. 이에, 본 논문에서는 기존 세대인 1～5세대 TFT-LCD 공장 현장에서 노광기의 진동실태를 수집하여 파악하고 Maker에서 제시하는 자료와 비교/평가하고, 문제점을 확인한다. 이를 기초로 수정/보완되어야 할 사항을 검토하며, 차세대인 6∼7세대 노광기에 대한 진동저감 대책을 위한 시스템을 설계하는 절차서에 대한 예를 들었으며, 최적의 진동저감 대책에 대한 설계안의 방향을 제시하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.302-312
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• 2000

Digital TV tuner for 8-VSB modulation was developed with satisfying the requirements of ATSC. Double frequency conversion and active tracking filter was used in order to suppress IF beat and image band, which results in reducing the interference between adjacent channels and multi-channels. The implemented digital TV tuner has excellent performance such as the wide dynamic range, good flatness in passing band, and low phase noise. The developed tuner is available to handle the digital and analogue television signal at the same time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.511-516
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• 2006

In this raper, we propose the Sequentiel Couleur Avec Memoire or Sequential Color with Memory (SECAM) video encoder system using modified anti-cloche filters and the SECAM video decoder system using a band pass filter (BPF) and an error-free square root. The SECAM encoder requires an anti-cloche filter recommended by International Telecommunication Union-Recommendation (ITU-R) Broadcasting service Television (BT) 470. However, the design of the anti-cloche filter is difficult because the frequency response of the anti-cloche filter is very sharp around rejection-frequency area. So, we convert the filter into a hish pass filter (HPF) by shifting the rejection frequency of 4.286MHz to 0Hz frequency. The design of HPF becomes very easy, compared to that of the anti-cloche filter. The proposed decoder also uses an error-free square root, two differentiators and trigonometric functions to extract color-component information of Db and Dr accurately from frequency modulation (FM) signals in SECAM systems. Also, the BPF in decoder it used for removing color noise in chrominance and dividing CVBS into chrominance and luminance. The proposed systems are experimentally demonstrated with Altera FPGA APEX20KE EP20K1000EBC652-3 device and TV sets.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.922-924
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• 2015

Recently, the image processing technologies using the public media such as the film, TV, camera and advertisement have been rapidly developed. However, the deterioration occurs with the image in the process of data processing, transmission and storage, and the typical cause of such deterioration is the salt and pepper noise. Typical filters to remove the salt and pepper noise include CWMF(center weighted median filter) and AMF(adaptive median filter) but such filters bring more or less insufficient characteristics of noise removal and visual error as the noise density gets higher. Thus, this paper proposed the median filter which applied the local mask segmented to 4 areas in order to remove the salt and pepper noise effectively and used PSNR(peak signal to noise ratio) as a criterion of judgment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.613-623
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• 2000

Digital TV tuner for 8-VSB modulation was developed with satisfying the requirements of ATSC. The double frequency conversion and the active tracking filter in the front-end were used to reduce interference of the adjacent channels and multi-channels, which suppress If beat and image band. However, it was impossible to get frequency mapping between tracking filter and first VCO(Voltage Controlled Oscillator) in the double conversion digital TV tuner differing from conventional NTSC tuner. This paper, therefore, suggests the available structure and a new method for automatic frequency selection by obtaining the mapping of frequency characteristic over tracking voltage and the combined hardware which compose of Micro-controller, EEPROM, D/A(Digital-to-Analog Converter), OP amp and switch driver to solve above problems.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.773-778
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• 2019

Images using X-rays are essential to diagnosis, but noise is inevitable in the image. To compensate for this, a total variation (TV) algorithm was presented to reduce the patient's exposure dose while increasing the quality of the images. The purpose of this study is to verify the effect on the image quality in radiographic imaging according to the thickness of the additional filtration plate through simulation, and to evaluate the usefulness of the TV algorithm. By using the Geant4 Application for Tomographic Emissions (GATE) simulation image, the actual size, shape and material of the Polymethylmethacrylate (PMMA) phantom were identical, the contrast to noise ratio (CNR) and coefficient of variation (COV) were compared. The results showed that the CNR value was the highest and the COV the lowest when applying the TV algorithm. In addition, we can acquire superior CNR and COV results with 0 mm Al in all algorithm cases.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.27-32
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• 1984

In SAW filters with a small aperture, diffraction effect is not negligible and degrades the frequency response near the trap. A computer simulation program for diffraction analysis is developed, and an effective diffraction compensation method is proposed to compensate the diffraction effect. A TV-lF SAW filter was designed with the diffraction taken account by the proposed method, which satisfies given frequency specifications.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.408-411
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• 2004

Color filter is a fundamental and necessary component to make a full-color TFT-LCD, its quality intensively influence the performance of TFT-LCD in the application of Notebook Computer, Monitor and Television. Color filter in chromaticity also make an effect for human visual system and video enjoyment. Recently, mother glass size is enlarged for demand of large-size panels and new generation color .filter technology for large-size liquid crystal cell panels is also developed. Here, latest generation color filter technology in TFT-LCD will be discussed.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.17-26
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• 1984

This paper reports the design methods and fabrication processes developed for a TV-lF SAW filter. The windowing method, the frequency sampling method, and the time sampling method were studied and compared to obtain a satisfactory initial impulse response. To obtain high attenuation near the trap frequency, diffraction effects were compensated. The 4fo sampling technique was used for avoiding multiple reflections at finger edges and obtaining an asymmetrical frequency response, and effective photolithographic techniques were used for electrode fingers with 11.2$\mu$ width. The developed filter is of sufficiently small size to be cost-effective and satisfies the industry specifications required for mass production.