• Journal of the Korean Society of Radiology
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• 제11권1호
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• pp.37-42
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• 2017

We measured the absorbed dose and the area dose using an ionization chamber type of area dose product (DAP) meter and measured the calibration factor in the X-ray examination. In the indirect dose measurement method, the detector was installed in the radiation part of the X-ray equipment, and the measured value was calculated as the dose at the exposure part. The instrument used to calculate the calibration factor was an X-ray equipment (DK-550R / F, DongKang Medical Co., Ltd., Seoul, Korea). The calibration method for the calibration factor was to connect the DAP meter (PD-8100, Toreck Co. Ltd., Japan) to the calibration dosimeter tube voltage of 70 kV, tube current of 500 mA, 0.158 sec. The reference dosimeter used a semiconductor (DOSIMAX plus A, Scanditronix, $Wellh{\ddot{o}}fer$, Germany). After installing the DAP meter on the front of the multi-collimator of the ionization chamber, the calibration factor of the dosimeter was obtained using the reference dosimeter for accurate dose measurement. Experimental exposure values and values from the calibration dosimeter were calculated by multiplying each calibration factor. The calibration factor was calculated as 1.045. In order to calculate the calibration coefficient according to the tube voltage in the ionization type DAP dosimeter, the absorbed dose and the area dose were calculated and the calibration factor was calculated. The corrective area dose was calculated by calculating the calibration factor of the DAP meter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제40권3호
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• pp.230-236
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• 2012

The purpose of this research is to determine the calibration constants of the wind speed measurement systems required to calculate the wind tunnel velocity in the test section. In the present work, the aerodynamic calibration tests of the test section were conducted in the Agency for Defense Development's Low-Speed Wind Tunnel. The test speed ranged from 10 to 100 m/s with a reference pitot-static pressure probe. The validity of the calibration results was evaluated by comparing them with the previous calibration constants. The calibration results show that fair to good agreement is obtained with resonable accuracy.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.45-45
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• 2010

반도체 및 디스플레이 산업에 사용되는 진공펌프의 효율이 증대됨에 따른 성능 평가 기술의 향상 과 미세 유량을 조절 및 측정할 수 있는 시스템의 개발이 요구되고 있다. 유량 시스템 중 소닉노즐은 기체 유량 측정 표준기로 사용되고 있다. 또한 유량 측정에 있어서 사용상의 편리성, 이동성, 재현성 등 여러 가지의 장점을 가지고 있어 산업 현장에서 많이 사용되고 있다. 본 연구는 소닉노즐을 넓은 유량 범위에서 사용할 수 있도록 소닉노즐의 유출계수 교정을 목적으로 한다. ISO 9300에서 제시한 사양에 맞추어 목 직경 0.03 mm와 0.2 mm 그리고 1.6 mm의 소닉노즐을 제작하였다. 한국표준과학연구원에서 진공용 유량측정 장치로 개발된 정적형 유량계를 이용하여 제작된 3 종의 소닉노즐 유출계수를 확장불확도 3% 이내로 교정하였다. 교정된 소닉노즐의 유량 측정범위는 약 0.6~90, 000 cc/min 범위를 갖는 것으로 나타났으며, 사용유동 조건에 해당되는 레이놀드 수(Reynolds number) 범위는 26~75, 700 으로 확인되었다. 이러한 결과는 교정된 소닉노즐을 이용하여 진공공정에서 필요한 극 미세 유량의 정밀측정을 가능하게한 새로운 연구결과로 판단된다. 교정된 소닉노즐을 이용하여 진공펌프의 배기속도 측정결과는 기 구축된 정적법을 이용한 배기속도 측정결과와 3% 이내의 오차범위내로 매우 잘 일치함을 보였다. 교정된 소닉노즐은 향후 반도체 및 디스플레이 공정에 사용되는 다양한 진공펌프들의 배기속도를 현장에서 간단하게 평가할 수 있는 '현장 성능평가 장치'에 활용할 예정이며, 현재 공정현장에서 배기속도 측정에 널리 사용 중인 MFC를 대체할 수 있을 것으로 예상된다.

• Journal of the Korean Society of Radiology
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• 제12권1호
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• pp.31-37
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• 2018

In the surface contamination test using the end-window Geiger-Muller type counter, the wrap is used as a method for protecting the detector exposed to the outside in order to measure the beta-rays. We analyze the effect of this method on the measurement rate and the correction factor, and wanted to make it clear to radiation workers that excessive use of the wrap can affect the measured value of the beta-rays. The experimental method was to compare and analyze the change of the beta-rays measurement counting rate and the calibration factor according to the wrap thickness using the beta-rays with different energy of 3 KBq, 1.5 KBq and 0.3 KBq. The subjects of this study were the end-window Geiger-Muller type counter which were held at the calibration center certified by Korea Laboratory Accreditation Scheme (KOLAS) in March 2012, Cl-36 (Chlorine) and Sr-90 (Strontium) were used as the source of beta radiation. The measurement counting rate decreased with increasing wrap thickness, and the calibration factor increased with increasing wrap thickness. Since the changes of the measurement counting rate and the calibration factors can reduce the accuracy of the instrument readings, but also have a significant impact on detector contamination and damage, so there is a need to find out what thickness of wrap is most effective. If we using a wraps with thickness that show a low rate of change of the measurement counting rate and the calibration factor, it will protect the detector and minimize the effect on the measured value of the beta-rays.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제17권12호
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• pp.98-106
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• 2016

Measurements of the elastic modulus and hardness using a nano indentation machine rely on the equation for the fitted contact area, which is valid for only sink-in materials. For most soft engineering materials that involve pile-up behavior rather than sink-in, the contact area equation underestimates the contact area and thus overestimates the elastic modulus and hardness. This study proposes a correction method to amend erroneous hardness measurements in pile-up situations. The method is a supplemental derivation to the original hardness measurement with the known value of the elastic modulus. The method was examined for soft engineering metals, Al 6061 T6 and C 12200, via tensile tests, nano indentation tests, impression observations, and finite element analysis. The proposed technique shows reasonable agreement with the analytical results accounting for strain gradient plasticity from a previous study.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.410-413
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• 2003

We have developed the measurement system for the high power laser The absorber is made of gold-plated copper cavity. The calibration heater is using a manganin(CuMn12Ni ; Isabellenhutte) coil, and output power is measured by using of resistance bridge with composed manganin and copper coil. Developed system can measure for 5∼1000w laser output power range. Calibration factors are 489.13 J/mV at 100W range and 489.13 J/mV at 500W range. Correction factors are 0.99 at 100W range and 1.006 at 500W range.

• Proceedings of the KIEE Conference
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2059_2060
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• 2009

본 연구에서는 표준 용량기와 표준 저항을 이용하여 전기용량 브리지의 손실계수와 커패시턴스 비를 측정하여 전기용량 브리지를 평가하는 방법을 개발하였다. 이를 적용하면 기존의 해외 인증기관에서 성능평가를 의뢰했을 때 소요되는 교정기간을 단축하고, 교정 비용을 감소시킬 수 있다. 또한 현장에서 사용되고 있는 장비를 해외 인증기관에 교정 의뢰할 경우 그 기간 동안 장비를 사용할 수 없는 문제를 해결할 수 있다. 측정 범위는 손실계수의 경우 $1{\times}10^{-6}{\sim}7.5{\times}10^{-3}$의 범위까지 광범위하게 측정하였고, 커패시턴스 비는 $C_N{\times}0.1{\sim}C_N{\times}10^3$�劉沮� 측정하였다. 이로부터 제조사에서 제공하고 있는 전기용량 브리지의 성능을 확인이 가능하게 되었다.

• Aerospace Engineering and Technology
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• 제4권2호
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• pp.117-125
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• 2005

Generally, the inertial navigation and guidance unit uses AF(Analog-to-Frequency) converters which convert analog signals into frequency signals to enhance a measurement accuracy of gyroscope and accelerometer outputs. The confidence level of AF converter is guaranteed by a prudential decision of calibration procedure and a performance of periodic calibration test. In this paper, we focus on the synchronous charge balance type AF converter which has a separate positive or negative current input and its calibration method is described. The calibration tests are classified into the scale factor error calibration and the bias calibration. These tests are automatically performed by the calibration program.

• Journal of Korea Port Economic Association
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• 제39권2호
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• pp.129-141
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• 2023

This study analyzes the dynamic characteristics of daily freight rates of dry bulk and tanker shipping markets and their forecasting accuracy by using the error correction models. In order to calculate the error terms from the co-integrated time series, this study uses the common stochastic trend model (CSTM model) and vector error correction model (VECM model). First, the error correction model using the error term from the CSTM model yields more appropriate results of adjustment speed coefficient than one using the error term from the VECM model. Furthermore, according to the adjusted determination coefficients (adjR²), the error correction model of CSTM-model error term shows more model fitness than that of VECM-model error term. Second, according to the criteria of mean absolute error (MAE) and mean absolute scaled error (MASE) which measure the forecasting accuracy, the results show that the error correction model with CSTM-model error term produces more accurate forecasts than that of VECM-model error term in the 12 cases among the total 15 cases. This study proposes the analysis and forecast tasks 1) using both of the CSTM-model and VECM-model error terms at the same time and 2) incorporating additional data of commodity and energy markets, and 3) differentiating the adjustment speed coefficients based the sign of the error term as the future research topics.

• Nuclear Engineering and Technology
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• 제10권3호
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• pp.137-144
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• 1978

A method is presented here in order to determine a nonlinearity correction of observed counter rates in a GM counter. An expression, which is developed under the assumption of dead time dependence on counting rates, gives good agreement with the results obtained from the experimental work. The variation of pulse voltages from a GM counter with counting rates was measured with the aid of pulse height analyzer. This method gives accurate values for the dead time over a wide range of counting. The technique as outlined allows tile exact correction of the nonlinearity caused by dead time loss. It was observed that the dead time decreases as the counting rate increases.