• Journal of the Semiconductor & Display Technology
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• v.23 no.1
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• pp.52-55
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• 2024

In this paper, a state change study was conducted through Frequency Domain Reflectometry (FDR) technology for the process chamber of plasma equipment for semiconductor manufacturing. In the experiment, by direct connecting the network analyzer to the RF matcher input of the 300 mm plasma enhanced chemical vapor deposition (PECVD) chamber, S11 was measured in a situation where plasma was not applied, and the frequency domain reacting to the chamber state change was searched. Response factors to changes in the status, such as temperature, spacing of the heating chuck, internal pressure difference, and process gas supply state were confirmed. Through this, the frequency domain in which a change in the reflection value was detected through repeated experiments. The reliability of the measured micro-displacement was verified through reproducibility experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.88-90
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• 2012

This paper describes a 10-bit 10-MS/s asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) with a rail-to-rail input range. The proposed SAR ADC consists of a capacitor digital-analog converter (DAC), a SAR logic and a comparator. To reduce the frequency of an external clock, the internal clock which is asynchronously generated by the SAR logic and the comparator is used. The time-domain comparator with a offset calibration technique is used to achieve a high resolution. To reduce the power consumption and area, a split capacitor-based differential DAC is used. The designed asynchronous SAR ADC is fabricated by using a 0.18 um CMOS process, and the active area is $420{\times}140{\mu}m^2$. It consumes the power of 0.818 mW with a 1.8 V supply and the FoM is 91.8 fJ/conversion-step.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.414-422
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• 2013

This paper describes a 10-bit 10-MS/s asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) using a split-capacitor-based differential digital-to-analog converter (DAC). SAR logic and comparator are asynchronously operated to increase the sampling frequency. The time-domain comparator with an offset calibration technique is used to achieve a high resolution. The proposed 10-bit 10-MS/s asynchronous SAR ADC with the area of $140{\times}420{\mu}m^2$ is fabricated using a 0.18-${\mu}m$ CMOS process. Its power consumption is 1.19 mW at 1.8 V supply. The measured SNDR is 49.95 dB for the analog input frequency of 101 kHz. The DNL and INL are +0.57/-0.67 and +1.73/-1.58, respectively.

• Journal of Internet Computing and Services
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• v.8 no.3
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• pp.33-43
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• 2007

In this proper, we proposes a robust watermarking against the lossy compression in the Hadamard domain. The Hadamard matrix consists of only 1 or -1 and can be computed veru fast. The Hadamrd transform has the inverse transform therefore it is able to be applied into the watermarking technology. In embedding process, we select 10 coefficients from intermediate frequency domain and create two watermark patterns. In extraction process, we use the watermark patterns and compare them to detect the watermark information. When we use the standard image ($512{\times}512$) and binary watermark image ($64{\times}64$), the results of these examines are PSNR for $38{\sim}42dB$ and BER for $3.9{\sim}12.5%$. The JPEG QF between 30 and100, naked human eyes can detect to watermark image easily. The experimental results show that performance of Hadamard domain is better than those of DCT, FFT, and DWT.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.05a
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• pp.61-64
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• 2001

본 논문은 Self Organizing Map을 이용한 한국어의 모음 10개를 인식하는 것을 다루고 있다. 분류기로서 우수한 성능을 보이고 있는 Self Organizing Map의 출력 층을 2차원으로 구성하여 짧은 시간 간격으로 주파수 도메인에서 벡터화 되어진 음성을 입력 층에 인가하여 유사한 출력 층의 분포를 이용하여 모음 10개를 인식하는 분류기로서의 가능성을 보여줄 것이다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.859-861
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• 2001

본 논문은 오디오의 masking특성을 적용한 심리음향 모델을 이용하여 오디오의 고음질을 보장하면서 잡음과 압축 등의 공격에 강한 오디오 워터마킹 방법을 제안한다. 제안하는 워터마킹 방법은 심리음향 모델에 의해 생산되는 masking thresholds와 원신호의 power spectral density의 각 주파수별 차이 에너지를 이용하여 시간도메인에서 워터마크를 삽입하는 방법으로 오디오의 품질을 유지할 수 있다. 워터마크로는 자기상관성이 강한 PN-시퀀스를 이용하여 강인한 워터마킹을 구현한다. 그리고 PN-시퀀스와 같은 이진 시퀀스 워터마크의 검출을 위한 유사도 측정식을 제안한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.66-73
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• 2024

Stay-cable is one of the most important load carrying members in cable-stayed bridges. Monitoring structural integrity of stay-cables is crucial for evaluating the structural condition of the cable-stayed bridge. For stay-cables, tension and damping ratio are estimated based on modal properties as a measure of structural integrity. Since the monitoring system continuously measures the vibration for the long-term period, data acquisition systems should be stable and power-efficiency as the hardware system. In addition, massive signals from the data acquisition systems are continuously generated, so that automated analysis system should be indispensable. In order to fulfill these purpose simultaneously, this study presents an autonomous cable monitoring system based on domain-knowledge using IoT for continuous cable monitoring systems of cable-stayed bridges. An IoT system was developed to provide effective and power-efficient data acquisition and on-board processing capability for Edge-computing. Automated peak-picking algorithm using domain knowledge was embedded to the IoT system in order to analyze massive data from continuous monitoring automatically and reliably. To evaluate its operational performance in real fields, the developed autonomous monitoring system has been installed on a cable-stayed bridge in Korea. The operational performance are confirmed and validated by comparing with the existing system in terms of data transmission rates, accuracy and efficiency of tension estimation.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.448-450
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• 2001

본 논문에서는 웨이블릿 변환된 영상으로부터 바코드 영역을 추출하기 위한 한 방법이 제안된다. 일반적으로 택배 등의 물류처리에서 사용되는 바코드는 직선 형태의 바로 구성되어지며, 물체의 윗면에 붙여진 바코드 라벨의 방향에 따라 바코드의 방향은 수직, 수평, 대각선의 방향으로 나타난다. 제안된 방법에서는 이러한 바코드의 수직, 수평, 대각선 방향의 주파수특성을 독립적으로 잘 반영하는 웨이블릿 변환의 특성을 활용하여 각각의 주파수 대역별로 바코드 영역을 검색하여 바코드 영역의 후보를 검출한다. 바코드의 후보 영역이 검출되면, 바코드의 후보 영역은 바코드의 길이 방향의 스캔 및 검증 과정을 통해 바코드 영역인지 최종 판별된다. 다양한 영상에 대한 실험을 통해 제안된 방법이 효과적임이 증명되었다.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.583-585
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• 2011

이 논문에서는 비접촉 방식의 심박 및 호흡 검출이 가능한 FFT를 이용하는 새로운 검출 방식의 알고리즘을 제안한다. 기존 FFT 방식은 주파수 도메인에서 필터링을 수행한 후 IFFT 후 특징점 추출 알고리즘을 수행하여 심박 및 호흡을 추출한다. 이 논문에서는 제안된 FFT 방식을 사용하여 기존의 FFT 방식과 달리 FFT를 한 후 주파수 영역에서 바로 심박수 및 호흡수를 추출할 수 있음을 제안한다.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.691-700
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• 1995

Most fractal image codings using fractal concept require long encoding time because a large amount of computation is needed to find an optimal affine transformation point. Such a problem can be solved by designing a block classifier fitted to characteristics of image blocks. In general, it is possible to predict more precise and various types of blocks in frequency domain than in spatial domain. In this paper, we propose a block classifier to predict the block type using characteristics of DCT(Discrete Cosine Transform). This classifier has merits to enhance the quality of decoded images as well as to reduce the encoding time meeting fractal features. AC coefficient values in frequency domain make it possible to predict various types of blocks. As the results, the number of comparisons between a range block and the correspoding domain blocks to reach an optimal affine transformation point can be reduced. Specially, signs of DCT coefficients help to find the optimal affine transformation point with only two isometric transformations by eliminating unnecessary isometric transformations among eight isometric transformations used in traditional fractal codings.