• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.5
• /
• pp.682-686
• /
• 2016

A fully differential RC calibrator for accurate cut-off frequency of a programmable channel selection filter is proposed. The proposed RC calibrator consists of an RC timer, clock generator, synchronous counter, digital comparator, and control block. To verify the proposed RC calibrator, a six-order Chebyshev programmable low-pass filter with adjustable 3 dB cut-off frequency, which is controlled by the proposed RC calibrator, was implemented in a $0.18-{\mu}m$ CMOS technology. The channel selection filter with the proposed RC calibrator draws 1.8 mA from a 1.8 V supply voltage and the measured 3 dB cut-off frequencies of the channel selection LPF is controlled accurately by the RC calibrator.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.2
• /
• pp.133.2-133.2
• /
• 2011

KVN phase Calibrator Survey(KVNCS)는 VLBI 관측 시 대기의 불규칙한 수증기 분포로 인한 visibility 위상의 불규칙한 변화를 보정하기 위해 도입되는 phase-referencing 기법 등에서 필수요소인 위상보정 calibrator를 얻기 위한 연구이다. Phase-referencing 기법을 이용하여 위상을 보정하기 위해서는 대상 천체의 근접한 곳에 비교적 compact한 calibrator가 존재해야 한다. 또한 Asaki et al.(1996)에 의하면 대기의 coherence structure가 유지되기 위해서는 두 천체가 적어도 $5^{\circ}$ 이내의 분리각을 가져야 한다. 위상보정 calibrator에 대한 연구는 주로 2, 8GHz 대역에서 진행되어 왔고 최근에는 22GHz에서 VLBI 관측이 진행되고 있지만 천구상의 특정 영역에 국한되거나 calibrator들 간의 분리각이 여전히 크다. KVNCS는 천구상에서 calibrator의 분포를 좀 더 고르게 하고 더 많은 calibrator를 얻어 적어도 $5^{\circ}$ 이내의 분리각을 구현하고자 한다. 먼저, 단일경을 이용하여 KVNCS의 대상을 확보하기위하여 이들의 플럭스를 정확히 측정하였다. 2, 8GHz 대역에서 관측된 VLBA(Very Long Baseline Array) Calibrator Survey(VCS) 목록을 기초로 power-law를 가정하여 22GHz에서 100mJy 이상일 것으로 예상되는 천체 2503개를 KVNCS 단일경 연구의 후보로 선정하였다. KVN 연세와 울산 전파망원경경을 이용하여 2009년 12월부터 2011년 3월까지 2298개의 플럭스 측정 관측을 진행하여 22GHz에서 약 77%, 43GHz에서 약 23%의 검출률을 얻었다. 또한 이 천체들의 공간분포도 $5^{\circ}$의 분리각을 만족하는 것을 확인하였다. 앞으로 KVNCS 단일경 결과를 활용하여 KVN 각 사이트의 위치 정보를 비롯하여 22GHz KVN VLBI 관측을 통해 KVN 위상보정 calibrator를 확보 할 계획이다.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.5
• /
• pp.677-683
• /
• 2011

The present paper describes the setup of standard partial discharge calibrator for measuring partial discharge and estimating uncertainties. The standard PD calibrator was designed and set up, consisting of a digital pulse generator, capacitor modules, and a digital oscilloscope controlled by software developed in the laboratory. Using this software, averages of charges and rising times and their standard deviations in the measured pulses can also be calculated. The standard PD calibrator generates five types of pulses: single, double, random, oscillating, and long-rising. The coefficient sensitivities to estimate the uncertainties of pulses were extracted in the model circuit of the standard PD calibrator. The uncertainties of charges and rising times in pulses of the standard PD calibrator were estimated with single pulses. These values were 0.3%-1.4% in charges and 1.9%-7.0% in rising time; however, these values are lower than the limit values in IEC 60270.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.19 no.2
• /
• pp.108-111
• /
• 2015

Purpose Lately, in accordance with the increasing interest about Healthcare accreditation program and International laboratory accreditation scheme, requirements about the instrument quality management are gradually taking shape. In nuclear medicine In vitro laboratory, the most typical instruments are multi detector gamma counter and automatic dispensing system. Each laboratory continue with the quality control adequate for circumstances. The purpose of this study is to application and establish the new Calibrator[I-125]Set which is efficient at standardization of equipment quality management. Materials and Methods Deviation between detectors were measured with 12 solid samples of the Calibrator[I-125]Set. their activities differ from each other by less than 1%. Multi detector gamma counters are GAMMA-10;Shinjin medics. Inc, Goyansi, Korea(Gamma counter A), SR300;Stratec biomedical systems AG, Gewerbestr, Germany(Gamma counter B) and COBRA II; Packard Instrument Co. Inc, Meriden, USA(Gamma counter C). Evaluation of two automatic dispensing system used A, B liquid tracer of the Calibrator[I-125]Set. After dispensing and counting, calculated using the ratio of the measured value and proposed value. We used solution A for 20, 25ul and solution B for 50, 100ul. Method of data analysis and reference range was provided by kit documentation. Furthermore, we could calculate our counter efficiency indirectly. Results The CV(%) of measured values by Gamma counter A, B, C are 0.34, 0.70, 1.30. Calculated value are 1.05314, 2.10419, 4.08485. Provided reference range is less than 3. A dispensing system's calculated values are 0.986, 0.989, 1.023, 1.017 and B are 0.874, 0.725, 1.021, 0.904. Provided reference range is from 0.95 to 1.05. Also, counter's efficiency are 74.18, 72.79, 74.32% at counter A, B, C and efficiency of the one detector counter is 79.26%. Conclusion If using this Calibrator[I-125]Set after verifying whether quality assurance, is applicable to equipment quality management on behalf of the role of gold standard.

• Journal of the Korean Society of Radiology
• /
• v.15 no.3
• /
• pp.307-312
• /
• 2021

In nuclear medicine, radioactive isotope tracers are administered to the human body to obtain and evaluate disease morphological information and biological function information. Dose calibrator is a device used to measure the radioactivity of a single nuclide in medical institutions. Administration of the correct dose to the human body acts as an important factor in diagnosis and treatment, and measurement through a dose calibrator before administration is the most important factor. Dose calibrator performs daily quality control after installation in each medical institution. Quality control is a means of guaranteeing quality control after installation, and is essential for improving the quality of treatment and promoting patient safety. Therefore, accurate and standardized performance evaluation methods should be established. In this study, 3D printing was used for quantitative evaluation of quality control by increasing the accuracy and standardization of quality control. When the 3D printer was installed and reproducibility was tested, the error range of the expected value and reading value decreased by 0.302% in the F-18 nuclide and 0.09% in the ^99mTc-pertechnate nuclide than when the 3D printer was installed. The error rate for other nuclides was also found to have a low error rate for reproducibility tests when 3D printing was installed.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.2
• /
• pp.60.2-60.2
• /
• 2010

대기의 불규칙한 수증기 분포로 인해 VLBI 관측시 visibility 위상에 불규칙한 변화가 발생한다. 이를 보정하기 위해 phase-referencing 기법 등을 이용할 수 있다. KVN calibrator survey는 Phase-referencing 기법에 필수적인 위상보정 calibrator를 얻기 위한 연구이다. 2, 8GHz 대역에서 관측된 VLBA(Very Long Baseline Array) Calibrator Survey(VCS) 목록을 기초로 power-law를 가정하여 22GHz에서 100mJy 이상일 것으로 예상되는 천체 2503개를 KVN Calibrator Survey의 대상으로 선정하였다. 먼저 KVN 연세 전파망원경을 이용하여 2009년 12월부터 2010년 6월까지 22GHz에서 500mJy 이상으로 예상되는 천체 595개에 대한 플럭스 측정 관측을 진행하였고 22GHz에서 517개, 43GHz에서 226개의 천체를 검출하였다. 이어 200mJy 이상 500mJy 미만으로 예상되는 천체 983개에 대하여 추가 관측을 진행하고 있다. 그리고 플럭스가 측정된 천체들에 대하여 VLBI Exploration of Radio Astrometry(VERA)와 VLBA, 각각 K밴드에서 관측된 결과와 비교하여 중복되지 않은 천체들에 대해 VLBI 관측을 수행하여 천체의 위치와 구조에 대한 정보를 얻을 계획이다.

• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.11
• /
• pp.944-951
• /
• 2016

Resistance temperature detectors (RTDs) and thermocouple sensors are broadly used to measure temperatures in the engineering and research fields. The contents of this standard calibration procedure (SCP) describe procedures related to the calculation of an electrical temperature calibrator and show different ways to indicate the calibration results, such as measurement uncertainty. As an SCP for the electrical temperature calibrator has not been developed yet, we studied the SCP and found a solution to this problem. In this paper, we present a mathematical model of the data and measurement variations with the calibration data results.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.245-246
• /
• 2009

• The Journal of the Acoustical Society of Korea
• /
• v.41 no.1
• /
• pp.1-8
• /
• 2022

This paper identifies the cause of the high frequency calibration limit of the acoustic chamber type calibrator for microphone calibration and presents a method to improve it. By using a commercial finite element analysis software, we analyzed the calibration frequency limit of the acoustic chamber type calibrator through eigen-frequency and frequency domain analysis. Based on this, we designed and fabricated an acoustic chamber type calibrator that can precisely calibrate within 1 dB from about 2 Hz to 6.4 kHz and verified its performance through experiments. The acoustic chamber type calibrator fabricated through this study has the advantage of being able to calibrate multiple microphones simultaneously in a wide frequency range, so it can be usefully used for simple calibration for multiple microphones.

• Journal of IKEEE
• /
• v.20 no.4
• /
• pp.439-448
• /
• 2016

RTDs and thermocouple sensors are broadly used to measure its temperature in industry and research. The contents of this standard calibration procedure(SCP) describe procedures related to the calculation of Electrical Temperature Calibrator and show different ways to indicate the calibration results like the uncertainty in measurement. As of current, SCP of electrical temperature calibrator has not been established yet and we have some inconveniences and difficulties in the standard calibration work. To solve these problems, we have studied the calibration technique for RTD and thermocouple of temperature calibrator. In this paper, we present the mathematic model of its data and variations of measurement with the results of calibration data.