• Nuclear Engineering and Technology
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• 제51권2호
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• pp.432-438
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• 2019

In the study of nuclear structure, the fast timing technique can be used to measure the lifetime of excited states. In the paper, we have developed a new fast timing system, which is made up of two $LaBr_3:Ce$ detectors and a set of waveform sampling system. The sampling system based on domino ring sampler version 4 chip (DRS4) can digitize and store the waveform information of detector signal, with a smaller volume and higher timing accuracy, and the waveform data are performed by means of digital waveform analysis methods. The coincidence time resolution of the fast timing system for two annihilation 511 keV ${\gamma}$ photon is 200ps (FWHM), the energy resolution is 3.5%@511 keV, and the energy linear response in the large dynamic range is perfect. Meanwhile, to verify the fast timing performance of the system, the $^{152}Gd-2_1^+$ state form ${\beta}^+$ decay of $^{152}Eu$ source is measured. The measured lifetime is $45.3({\pm}5.0)ps$, very close to the value of the National Nuclear Data Center (NNDC: $46.2({\pm}3.9)ps$). The experimental results indicate that the fast timing system is capable of measuring the lifetime of dozens of ps. Therefore, the system can be widely used in the research of the fast timing technology.

• 한국초전도ㆍ저온공학회논문지
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• 제24권2호
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• pp.23-26
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• 2022

A lossless transport of an arbitrary waveform in a frequency range of 10⁶-10⁹ Hz through a conduction channel in a cryogenic temperature is of importance for a high-speed operation of quantum device. However, it is hard to use a commercial oscilloscope to directly detect the waveform travelling in a device located in a cryogenic system. Here, we developed a cryogenic voltage sampling technique by using a Schottky barrier gate prepared on a surface of a GaAs/AlGaAs device, which revealed that an incident rectangle waveform can transport through a 1 mm long two-dimensional conduction channel without waveform deformation up to 20 MHz, while further study is needed to increase the detection frequency.

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.429-440
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• 2007

A coded excitation has been studied to improve the performance for ultrasound imaging in term of SNR, imaging frame rate, contrast to tissue ratio, and so forth. However, it requires a complicated arbitrary waveform transmitter for each active channel that is typically composed of a multi-bit Digital-to-Analog Converter (DAC) and a linear power amplifier (LPA). Not only does the LPA increase the cost and size of a transmitter block, but it consumes much power, increasing the system complexity further and causing a heating-up problem. This paper proposes an optimized 1.5bit fourth order sigma-delta modulation technique applicable to design an efficient arbitrary waveform generator with greatly reduced power dissipation and hardware. The proposed SDM can provide a required SQNR with a low over-sampling ratio of 4. To this end, the loop coefficients are optimized to minimize the quantization noise power in signal band while maintaining system stability. In addition, the decision level for the 1.5 bit quantizer is optimized for a given input waveform, which results in the SQNR improvement of more than 5dB. Computer simulation results show that the SQNR of a FM(frequency modulated) signal generated by using the proposed method is about 26dB, and the peak side-lobe level (PSL) of its compressed waveform on receive is -48dB.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2164-2166
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• 1999

This paper is describes the measured electric field waveform radiated by lightning discharge. We have performed measurement and analysis of the electric fields associated with stepped leaders. Electric field measurement system was composed of hemisphere electric field sensor, measurement system of a distance from lightning strokes, automatical recording system, A/D board, personal computer etc. A/D board have high sampling time, high speed data processing, 8bit of resolution. Also, measured characteristics of stepped leaders radiated by were analyzed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.686_687
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• 2009

The traceability maintenance system for the AC voltage and current has been developed at the frequency range of 20 Hz to 100 Hz without using any compensation technique which is used at thermal converter (TC) ac-dc transfer system at low frequencies. The system uses a digital voltmeter (DVM) as a data acquisition system of the input waveform and stored data in memory. The developed algorithm acquires and processes the sampling data to calculate the root mean square (rms) value of the input voltage of DVM which operates at DC 10 V range for better accuracy. The best uncertainty of the AC voltage measurements is $3 {\mu}V/V$ within the frequency range. The best uncertainty of the AC current measurements is better than the $5 {\mu}A/A$ and mainly depend on the current to voltage converter, ac-dc current shunt or Current Transformer (CT), used for the measurement

• 대한전기학회논문지:시스템및제어부문D
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• 제49권1호
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• pp.48-53
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• 2000

In this paper, we develop a TMS320C31 (60MHz) digital signal processor (DSP) board to synthesize gradient waveforms for Spiral Scan Imaging (SSI), which is one of the ultra fast magnetic resonance imaging (MRI) methods widely used. In SSI, accurate gradient waveforms are very essential to high quality magnetic resonance images. For this purpose, sampling rate for synthesizing the gradient waveforms is set twice as high as the data sampling rate. With the developed DSP boards accurate gradient waveforms are obtained. Ultra fast spiral scan imaging with the developed with the developed DSP board is currently under development.

• 센서학회지
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• 제21권5호
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• pp.352-358
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• 2012

A sensor network system can be an efficient tool for healthcare telemetry for multiple users due to its power efficiency. One drawback is its limited data size. This paper proposed a real-time application of data compression/decompression method in u-Health monitoring system in order to improve the network efficiency. Our high priority was given to maintain a high quality of signal reconstruction since it is important to receive undistorted waveform. Our method consisted of down sampling coding and differential Huffman coding. Down sampling was applied based on the Nyquist-Shannon sampling theorem and signal amplitude was taken into account to increase compression rate in the differential Huffman coding. Our method was successfully tested in a ZigBee and WLAN dual network. Electrocardiogram (ECG) had an average compression ratio of 3.99 : 1 with 0.24% percentage root mean square difference (PRD). Photoplethysmogram (PPG) showed an average CR of 37.99 : 1 with 0.16% PRD. Our method produced an outstanding PRD compared to other previous reports.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.101-108
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• 2020

In order to solve the contradiction between requirements of high sampling rate for acquiring accurate energy information of pulses and large amount of data to be processed timely, the method with an algorithm to correct errors caused by reducing the sampling rate is normally used in front-end read-out system, which is conductive to extract accurate energy information from digitized waveform of pulse. The functions and effects of algorithms, which mainly include polynomial fitting with different fitting times, double exponential function fitting under different sampling modes, and integral area algorithm, are analyzed and evaluated, and some meaningful results is presented in this paper. The algorithm described in the paper has been used preliminarily in a prototype system of Positron Emission Tomography (PET) for heavy-ion cancer therapy facility.

• 한국자기학회지
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• 제7권6호
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• pp.327-333
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• 1997

페라이트, 비정질 코아등의 고주파 연자성재료의 고주파 자기특성 데이터를 디지타이징 방법으로 얻고, 철손 및 B-H 곡선, 투자율을 자동적으로 측정할 수 있는 고주파 자기특성측정장치를 제작하였다. 본 시스템은 교류 인가를 위한 신호발생기와 전력증폭기, 인가자장을 게측하기 위한 전류측정용 저항, H 및 B 신호를 디지타이징 (digitizing)하기 위한 대역폭 500 MHz, 샘플링속도 1 Gs/s의 디지털 오실로스코프, 시스템 제어에 사용되는 GPIB 케이블 및 퍼스널 컴퓨터로 구성되었다. 자계 H 계측을 위한 전류센서로서 저항기(resistor)와 Rogowski 코일을 비교 검토한 결과 고주파 변류기 (current transformer : 이하 CT)가 주파수 특성과 노이즈 억제효과에서 보다 우수하였다. 측정시스템에 동작자속밀도 설정, 비대칭 B-H 곡선의 보정, 구형파등의 다양한 파형지원등의 기능을 부가하였다.

• 한국컴퓨터정보학회논문지
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• 제12권6호
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• pp.97-104
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• 2007

본 논문에서는 오디오를 내용기반으로 분석, 분류, 검색하기 위하여 사용되어 온 특징 추출 기법의 문제점을 제시하며, 새로운 검색 방법을 위해 하나의 전처리 과정을 제안한다. 기존 오디오 데이터 분석은 샘플링을 어떻게 하느냐에 따라 특징 값이 달라지기 때문에 같은 음악이라도 다른 음악으로 인식될 수 있는 문제를 갖고 있다. 따라서 본 논문에서는 다양한 포맷의 오디오 데이터를 내용 기반으로 검색하기 위해 PCM 데이터의 파형 정보 추출 방법을 제안한다. 이 방법을 이용하여 다양한 포맷으로 샘플링 된 오디오 데이터들이 같은 데이터임을 발견 할 수 있으며, 이는 내용기반 음악검색에 적용 할 수 있을 것이다. 이 방법의 유효성을 증명하기 위해 STFT를 이용한 특징 추출과 PCM 데이터의 파형 정보를 이용한 추출 실험을 하였으며, 그 결과 PCM데이터의 파형 정보 추출 방법이 효과적임을 보였다.