• 설비공학논문집
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• 제14권5호
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• pp.415-423
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• 2002

An experimental study using a psychrometric calorimeter was conducted to investigate the temperature and pressure mea surement errors permitted for determining cooling capacity of an air conditioner. First, the instrument calibration was made in accordance with the related test methods and guidelines in order to accurately evaluate basic performance (cooling capacity and airs flow rate). Secondly, a parametric study was performed to examine the effect of measurement error involved if temperature and pressure measuring instruments on the cooling capacity calculation. From the results, it was found that the degree of accuracy for both temperature and pressure measurements played an important role on the error occurring in the determination of cooling capacity and needed to be maintained within a certain value to guarantee required accuracy of cooling capacity.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.525-543
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• 2010

Testing and validation processes are critical tasks in developing a new hardware platform based on a new technology. This paper describes a series of experiments to evaluate the performance of a newly developed MEMS-based wireless sensor node as part of a wireless sensor network (WSN). The sensor node consists of a sensor board with four accelerometers, a thermometer and filtering and digitization units, and a MICAz mote for control, local computation and communication. The experiments include calibration and linearity tests for all sensor channels on the sensor boards, dynamic range tests to evaluate their performance when subjected to varying excitation, noise characteristic tests to quantify the noise floor of the sensor board, and temperature tests to study the behavior of the sensors under changing temperature profiles. The paper also describes a large-scale deployment of the WSN on a long-span suspension bridge, which lasted over three months and continuously collected ambient vibration and temperature data on the bridge. Statistical modal properties of a bridge tower are presented and compared with similar estimates from a previous deployment of sensors on the bridge and finite element models.

• 한국유체기계학회 논문집
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• 제14권1호
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• pp.42-47
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• 2011

Measurement uncertainty analysis of fuel flow using turbine flowmeter was performed for the case of altitude engine test. SAE ARP4990 was used as the fuel flow calculation procedure, as well as the mathematical model for the measurement uncertainty assessment. The assessment was performed using Sensitivity Coefficient Method. 11 parameters involved in the calculation of the flow rate were considered. For the given equipment setup, the measurement uncertainty of fuel flow was assessed in the range of 1.19~1.86 % for high flow rate case, and 1.47~3.31 % for low flow rate case. Fluctuation in frequency signal from the flowmeter had the largest influence on the fuel flow measurement uncertainty for most cases. Fuel temperature measurement had the largest for the case of low temperature and low flow rate. Calibration of K-factor and the interpolation of the calibration data also had large influence, especially for the case of very low temperature. Reference temperature, at which the reference viscosity of the sample fuel was measured, had relatively small contribution, but it became larger when the operating fuel temperature was far from reference temperature. Measurement of reference density had small contribution on the flow rate uncertainty. Fuel pressure and atmospheric pressure measurement had virtually no contribution on the flow rate uncertainty.

• 한국광학회지
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• 제29권2호
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• pp.70-76
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• 2018

$0^{\circ}C$ 이하 적외선 복사온도계의 복사온도눈금 교정을 위해 기준 복사온도계 TRT2 (Transfer Radiation Thermometer 2, HEITRONICS)와 온도가변 흑체 ME30 (Model: ME30, HEITRONICS)을 사용하여 비교 교정장치를 구축하였다. 3개의 고정점(Ice ($0.01^{\circ}C$), In ($156.5985^{\circ}C$), Sn ($231.928^{\circ}C$))과 플랑크형 사쿠마-하토리식을 사용하고, $-50^{\circ}C$에서 TRT2의 내외삽 오차를 불확도에 포함시켜 TRT2의 복사온도 눈금을 교정하였다. ME30 흑체 개구에 공압으로 동작되는 뚜껑을 설치한 후 30초 동안만 뚜껑을 열고 복사온도를 측정함으로써 ME30 내에서 생기는 성에를 방지할 수 있었으며 비교 교정에 소요되는 시간도 반으로 줄일 수 있었다. $0{\sim}232^{\circ}C$ 영역 밖으로 벗어날수록 비교 교정장치의 불확도는 증가하며 $-20^{\circ}C$에서 확장 불확도는 0.26 K였다.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.673-683
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• 2016

This paper analyzes the accuracy of the methods used in calibrating the thermal power of Nigeria Research Reactor-1 (NIRR-1), a low-power miniature neutron source reactor located at the Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria. The calibration was performed at three different power levels: low power (3.6 kW), half power (15 kW), and full power (30 kW). Two methods were used in the calibration, namely, slope and heat balance methods. The thermal power obtained by the heat balance method at low power, half power, and full power was $3.7{\pm}0.2kW$, $15.2{\pm}1.2kW$, and $30.7{\pm}2.5kW$, respectively. The thermal power obtained by the slope method at half power and full power was $15.8{\pm}0.7kW$ and $30.2{\pm}1.5kW$, respectively. It was observed that the slope method is more accurate with deviations of 4% and 5% for calibrations at half and full power, respectively, although the linear fit (slope method) on average temperature-rising rates during the thermal power calibration procedure at low power (3.6 kW) is not fitting. As such, the slope method of power calibration is not suitable at lower power for NIRR-1.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1086-1087
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• 2009

A small temperature sensor is designed in a 0.35um CMOS process. Transistors operating in the intermediate inversion region are employed in the core of the sensor. This temperature sensor operates in $-50^{\circ}C{\sim}120^{\circ}C$ with ${\pm}2^{\circ}C$ of accuracy after two-point calibration. This temperature sensor can be placed in the active pixel area of a display panel to measure the temperature of the display panel for temperature compensation.

• 한국의학물리학회지:의학물리
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• 제19권1호
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• pp.49-55
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• 2008

본 연구는 MDCT에서 선량을 측정하는데 사용되는 ionization chamber의 calibration 전과 후의 calibration factor에 따른 선량과 촬영실의 온도, 기압의 보정(correction factor) 적용 유무에 따른 $CTDI_w$를 비교 분석하는데 있다. 2007년 3월 21일에 교정된 Model 2026C electormeter (RADICAL 2026C, USA)를 이용한 MDCT (GE light speed plus 4 slice, USA)와 head and body CT dosimetry phantom을 사용하여 측정된 값을 비교 분석하였다. 결과는 calibration factor와 주변 온도, 압력의 correction factor를 보정 해 준 $CTDI_w$ 값이 보정을 하지 않고 계산된 값보다 $0.479{\sim}3.162mGy$의 범위만큼 더 많은 선량 값이 계산되었고 실제 병원에서 사용하는 복부 일반 CT (abdomen routine CT) 조건에서의 환자선량을 측정한 결과 factor적용 전과 후의 유효선량 차는 최고 0.7 mSv의 차이가 남을 확인 할 수 있었다. 이러한 결과는 ionization chamber의 calibration과 촬영실 주변 온도와 압력이 환자선량의 측정과 계산에 중요한 요소임을 알 수 있다. 따라서 정확한 환자 선량 측정을 위해서는 촬영실 주변 온도와 압력뿐만 아니라 습도 및 recombination factor, x-ray beam quality 특성, 촬영조건(exposure conditions), 측정부위(scan region) 등에 대한 보정 factor들의 정확한 정보를 알아야 한다.

• 광물과 암석
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• 제35권1호
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• pp.65-73
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• 2022

지구/행성 내부의 다양한 지질학적 과정을 이해하기 위해서는 고온-고압 환경에서 지구 내부 구성물질의 특성을 이해하는 것이 필수적이다. 이러한 고압환경을 생성하기 위하여 사용되는 멀티 앤빌 프레스(multi-anvil press)는 주로 상부맨틀조건의 극한 상황을 재현하는데 사용된다. 멀티 엔빌프레스의 지질학적 사용을 위한 필수 보정 과정 중 하나는 압력을 생성하기 위한 프레스의 유압과 실제로 시료에 가해지는 압력 사이의 관계인 압력-부하 보정(pressure-load calibration)이다. 압력-부하 보정은 일반적으로 고온-고압 조건에서는 결정질 물질의 상전이를 이용해서 이루어지는데, 고온에서의 경우와 달리 저온(상온)의 경우 상전이 과정이 상대적으로 비효율적이므로 압력-부하 보정의 다른 방법론이 요구된다. 본 연구에서는 파이로프 조성(Mg₃Al₂Si₃O₁₂)의 비정질(비정질 파이로프)의 상온에서의 압축(cold compression)에 따라 발생하는 영구적인 고밀도화 현상(permanent densification)과 그 기원이 되는 알루미늄 배위 환경의 변화를 고해상도의 ²⁷Al MAS 및 3QMAS NMR 분광분석을 통해 정량화하고, 이로부터 압력에 따른 알루미늄의 배위수 변화를 이용해 14/8 HT 조립세트(assembly set)와 1,100톤 멀티 앤빌 프레스에 대한 상온에서의 압력-부하 보정을 수행하였다. 본 연구는 NMR분광분석을 이용하여 압력보정을 수행한 최초의 연구결과이며, 비정질 파이로프의 압축-감압에 따른 원자 단위에서의 비가역적 구조 변화는 섭입대 환경과 같은 저온 고압 환경에서 비정질 물질이 겪는 변화와 그에 따른 지질학적 현상의 이해고양에 실마리를 제공한다.

• 대한기계학회논문집B
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• 제27권11호
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• pp.1572-1578
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• 2003

Particle Image Thermometry(PIT) with liquid crystal tracers is used for visualizing and analysis of the bubbly flow in a vertical temperature gradient. Quantitative data of the temperature were obtained by applying the color-image processing to a visualized image, and neural-network was applied to the color-to-temperature calibration. This paper describes the method, and presents the transient mixing temperature patterns of the bubbly flow.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.814-822
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• 2022

The deployment of sensors for Structural Health Monitoring requires a complicated network arrangement, ground truthing, and calibration for validating sensor performance periodically. Any conventional sensor on a structural element is also subjected to static and dynamic vertical loadings in conjunction with other environmental factors, such as brightness, noise, temperature, and humidity. A structural model with strain gauges was built and tested to get realistic sensory information. This paper investigates different deep learning architectures and algorithms, including unsupervised, autoencoder, and supervised methods, to benchmark blind drift calibration methods using deep learning. It involves a fully connected neural network (FCNN), a long short-term memory (LSTM), and a gated recurrent unit (GRU) to address the blind drift calibration problem (i.e., performing calibrations of installed sensors when ground truth is not available). The results show that the supervised methods perform much better than unsupervised methods, such as an autoencoder, when ground truths are available. Furthermore, taking advantage of time-series information, the GRU model generates the most precise predictions to remove the drift overall.