• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권9호
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• pp.450-455
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• 2001

We proposed a new sensitivity verification method for the UHF partial discharge(PD) detection system. Initially, we measure the UHF power induced by 5 pC PD which takes place near UHF sensor. Subsequently, we inject the swept UHF signal from a network analyzer into the GIS and measure the attenuation of the signal along the 71S Both the UHF power by 5 pC PD and the attenuation make it possible to verify the sensitivity and spatial coverage of the PD detection system. This method doesn\`t require the calibration of injected pulse type UHF signal into the GIS and makes us precisely measure the attenuation in frequency domain.

• 한국음향학회지
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• 제41권1호
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• pp.1-8
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• 2022

본 논문은 마이크로폰 검교정을 위한 음향 챔버형 검교정기의 고주파 검교정 한계가 나타나는 원인을 밝히고 이를 향상시키는 방법을 제시한다. 상용 유한요소 해석 프로그램을 활용하여 고유 주파수 해석과 주파수 영역 해석을 통해 음향 챔버형 검교정기의 검교정 주파수 한계를 분석하였고, 이를 바탕으로 약 2 Hz 부터 6.4 kHz 까지 1 dB 수준 이내로 정교하게 검교정할 수 있는 음향 챔버형 검교정기를 설계 및 제작하고 실험을 통해 그 성능을 검증하였다. 본 연구를 통해 제안된 음향 챔버형 검교정기는 넓은 주파수 범위에서 다수의 마이크로폰을 동시에 검교정 할 수 있는 이점을 가지고 있어 다수의 마이크로폰을 위한 간편한 검교정에 유용하게 사용될 수 있다.

• 대기
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• 제33권5호
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• pp.549-560
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• 2023

This study evaluates three distinct observation methods, CRDS, OA-ICOS, and OF-CEAS, in greenhouse gas monitoring equipment for atmospheric CO₂ and CH₄ concentrations. The assessment encompasses fundamental performance, high-concentration measurement accuracy, calibration methods, and the impact of atmospheric humidity on measurement accuracy. Results indicate that within a range of approximately 500 ppm, all three devices demonstrate high accuracy and linearity. However, beyond 1000 ppm, CO₂ accuracy sharply declines (84%), emphasizing the need for caution when interpreting high-concentration CO₂ data. An analysis of calibration methods reveals that both CO₂ and CH₄ measurements achieve high accuracy and linearity through 1-point calibration, suggesting that multi-point calibration is not imperative for precision. In dynamic atmospheric conditions with significant CO₂ and CH₄ concentration variations, a 1-point calibration suffices for reliable data (99% accuracy). The evaluation of humidity impact demonstrates that humidity removal devices significantly reduce air moisture levels, yet this has a negligible effect on dry CO₂ concentrations (less than 0.5% relative error). All three observation method instruments, which have integrated humidity correction to calculate dry CO₂ concentrations, exhibit minor sensitivity to humidity removal devices, implying that additional removal devices may not be essential. Consequently, this study offers valuable insights for comparing data from different measurement devices and provides crucial information to consider in the operation of monitoring sites.

• 한국농공학회논문집
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• 제60권1호
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• pp.47-57
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• 2018

This study implemented the rainfall-runoff analysis of the Mekong River basin using the SWAT (Soil and Water Assessment Tool). The runoff analysis was simulated for 2000~2007, and 11 parameters were calibrated using the SUFI-2 (Sequential Uncertainty Fitting-version 2) algorithm of SWAT-CUP (Calibration and Uncertainty Program). As a result of analyzing optimal parameters and sensitivity analysis for 6 cases, the parameter ALPHA_BF was found to be the most sensitive. The reproducibility of the rainfall-runoff results decreased with increasing number of stations used for parameter calibration. The rainfall-runoff simulation results of Case 6 showed that the RMSE of Nong Khai and Kratie stations were 0.97 and 0.9, respectively, and the runoff patterns were relatively accurately simulated. The runoff patterns of Mukdahan and Khong Chaim stations were underestimated during the flood season from 2004 to 2005 but it was acceptable in terms of the overall runoff pattern. These results suggest that the combination of SWAT and SWAT-CUP models is applicable to very large watersheds such as the Mekong for rainfall-runoff simulation, but further studies are needed to reduce the range of modeling uncertainty.

• 소성∙가공
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• 제19권8호
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• pp.494-501
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• 2010

The main objective of this study is to examine the sensitivity of calibration curves of FEA of ring compression test to frictional shear factor. Ring compression test has been investigated by measuring dimensional changes at different positions of ring specimen and they include the changes in internal diameter at the middle and top section of the specimen, outer diameter at the middle and top section, surface expansion at the top surface, respectively. Initial ring geometries employed in analysis maintain a fixed ratio of 6 : 3 : 2, i.e. outer diameter : inner diameter : thickness of the ring specimen, which is generally known as 'standard' specimen. A rigid plastic material for different work-hardening characteristics has been modeled for simulations using rigid-plastic finite element code. Analyses have been performed within a definite range of friction as well as over whole range of friction to show different sensitivities to the interfacial friction for different ranges of friction. The results of investigation in this study have been summarized in terms of a dimensionless gradient. It has been known from the results that the dimensional changes at different positions of ring specimen show different linearity and sensitivity to the frictional condition on the contact surface.

• 대한원격탐사학회지
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• 제29권6호
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• pp.589-593
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• 2013

Sea Surface Temperature (SST) is the temperature close to the ocean's surface and affects the Earth's atmosphere as an important parameter for the climate circulation and change. The SST from satellite still has biases from the error in specifying retrieval coefficients from either forward modeling or instrumental biases. So in this paper, we performed sensitivity analysis using input parameter of the SST to notice that the SST is most affected among the input parameter. We used Infrared (IR) data from the Communication, Ocean, and Meteorological Satellite (COMS)/Meteorological Imager (MI) from April 2011 to March 2012. We also used the Global Space-based Inter-Calibration System (GSICS) correction to quality of the IR data from COMS. SST was calculated by substituting the input parameters; IR data with or without the GSICS correction. The results of this sensitivity analysis, the SST was sensitive from -0.0403 to 0.2743 K when the IR data were changed by the GSICS corrections.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.314-319
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• 2000

Back-face strain compliance (BFS compliance) for the four-point bend specimen has been calibrated for various crack length ratios. Finite element technique was employed to simulate four-point loading and calculate back-face strain of the bend specimen. The numerically determined strain variation along the back face indicates that the sensitivity to gage placement increases with crack length and back-face strain at the gage length less than O.2W, where W is the width of the bend specimen, can be measured within 5% deviation of the maximum BFS. Non-dimensional back-face strain compliance, -E'BCW, was calibrated with FE analysis and experiment. The experimentally determined compliance indicates good agreement with the numerical compliance and can be expressed as a function of crack length ratio.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.5-5
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• 2010

The depth of the object pointed by the laser beam is computed depending on the pixel position on the CCD There involved several number of internal and external parameters such as inter-pixel distance, focal length, position and orientation of the system components in the depth measurement error. In this paper, it is shown through the error sensitivity analysis of the parameters that the most important parameters in the sense of error sources are the angle of the laser beam and the inter pixel distance. Also, the calibration technique to minimize their effect for the depth computation is proposed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.444-446
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• 1995

This paper deals with semisphere-type sensor fo measuring the electric field waveforms by lightning discharges. The theoretical principle and design rule of the device are introduced, and also the calibration and application investigations are carried out. From the calibration experiments, the frequency bandwidth of the semisphere-type electric field measuring device ranges from 200 [Hz] to 1.56 [MHz], and the sensitivity of sensor is 0.96 [mV/V/m]. The electric field waveforms produced by lightning discharges were observed for June and August 1995. It is shown that the electric field waveforms produced at the distance of more than 50 [km] include only radiation component.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.298-302
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• 2002

Equivalent volume estimation of the coupler and two coupled microphones has a key role in standard microphone pressure calibration. The equivalent volume of the microphone is determined by the dynamic characteristics of the diaphragm system and front cavity. Therefore the modal parameters of diaphragm system - natural frequency and damping fatter - should be measured explicitly for the estimation of the equivalent volume. The diaphragm system is composed of the vibrating diaphragm, back slit behind diaphragm, pressure equalization vent, and front cavity which are acoustically coupled. In the measurement, the electrostatic actuator was used to excite the system with the swept sine, and the frequency response was obtained. The close actuator in front of the diaphragm must influence the radiation impedance of the system, and then the modal parameters. From the measured frequency response, the natural frequency and the damping factor could be estimated with the Complex exponential method based on the Prony model and the zero crossing real and imaginary plot.