• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.394-399
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• 1999

An automobile hot-film air flow sensor is deposited with platinum by sputtering method, patterned by photoresisted lift-off method, annealed in $1,000^{\circ}C$ and passivated with PI-2723. The TCR of the fabricated hot-film is about $3500\;ppm/^{\circ}C$. In the experiment, the output voltage of the sensor is in proportional to the fourth power root in the air mass flow range of 300 kg/h. The error in the full flow range is about ${\pm}0.7%$. In the range of air temperature of $-20^{\circ}C{\sim}120^{\circ}C$, the error is about ${\pm}1%$ that is ${\pm}2%$ lower than that of the reference sensor. Therefore, the fabricated hot-film air flow sensor satisfies the specification for automobile. Lower temperature error of the sensor provides to control the precise air/fuel ratio of automobile engine and results in improvement of a fuel mileage and the less amount of toxic gases emitted by automobile.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2007.05a
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• pp.151-152
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• 2007

ACP(Advanced Spent Fuel Conditioning Process)의 금속전환로에 $U_{3}O_{8}$을 공급하기 위하여 20 kgHM/batch의 $UO_{2}$ 펠릿(pellets)을 처리할 수 있는 공기산화로가 개발되고 있다. 그림 1은 산소농도 조절이 가능한 공기산화로이다. 공기산화로 이전의 공정인 슬리팅 장치에서 탈피복된 $UO_{2}$ 펠릿은 공기산화로로 운반되고, $500^{\circ}C$온도에서 공기를 공급하여 일정한 입도범위의 균질한 $U_{3}O_{8}$을 만든다. 그리고 다음공정의 금속전환장치로 이동된다. 본 논문에서는 모의연료의 산화에 대한 정확한 산소농도를 측정하고자 한다. 이를 위해서 갈바닉 센서와 지르코니움 센서가 사용되었고, 그 특성이 비교되었다. 14종의 금속 산화물이 혼합된 모의연료를 제조하여 산화실험이 수행되었으며, 시간변화에 따라 산소농도가 측정되었다. 산소농도 컨트롤러와 산소 센서를 사용한 공기산화로는 산소조절기에 의해 산소농도 100%까지 측정될 수 있다. 그림 2는 공기산화로의 산소농도를 조절할 수 있는 산소농도 측정시스템이다. 유량조절기(Mass Flow Controller)를 사용하여 질소와 산소의 혼합비를 변화시킬 수 있다. 또한 산소농도 측정시스템은 측정된 산소농도 값을 이용하여 $UO_{2}$의 산화시간을 계산하기 위하여 제작하였다. 산화시간 계산방법은 다음과 같다. 산소와 질소의 가스는 각각 40 L의 압력 봄베에 의해서 산소농도를 조절할 수 있는 공기산화로의 산소농도 측정시스템 안으로 유입된다. 유입된 산소와 질소의 배합은 컨트롤시스템 안에 있는 산소 유량조절기와 질소 유량 조절기를 사용하여 조절하며, 일정하게 혼합된 산소농도는 장치의 입구와 출구에서 산소 센서에 의해서 측정된다. 투입된 $UO_{2}$ 펠릿이 $500^{\circ}C$에서 반응하면서 공기산화로의 내부에 있는 산소농도가 감소된다. 이때 초기에 같았던 입력과 출력 농도가 시간의 흐름에 따라 감소되며, 펠릿이 완전히 산화됨과 동시에 출력 산소농도가 입력농도와 다시 같아질 때까지 소요된 구간이 산화시간이 된다.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.4
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• pp.846-856
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• 2001

An experimental study has been made to investigate the effect on wake flow and vortex shedding frequency by vortex stabilizer in Karman vortex type air flow sensor. The conditions investigated include 3 types of shapes and 3 types of separation distances of the vortex stabilizer. The phase averaged technique and smoke-wire flow visualization method are used to understand the detail information. The rolling up position of shear layer is fixed by the influence of the vortex stabilizer. Especially, the convex type vortex stabilizer has shown the more stable repeatability and linearity regarding the vortex shedding frequency compared to the other types.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.551-553
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• 2016

Since air compressor, as an essential equipment used in the factory and plant operations, accounts for around 20% of the total domestic electricity consumption, a real time sensor data monitoring based analysis for electricity consumption reduction is important. In particular, flow rates and pressures of these monitored variables has a direct correlation with the power consumption. This paper proposes a method to identify if the measurement error of the flow rate sensor comes from the sensor measurement limit through bivariate classification analysis of the flow rate and power using the EM (Expectation and Maximization) Algorithm and show how to enable more accurate analysis by the correlation between the flow rate and power on the right-censored data.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.77-82
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• 2023

The fuel cell in fuel cell electric vehicle utilizes oxygen in the atmosphere, which requires the use of an air cleaner system to minimize the intake of harmful pollutants. To estimate the performance of the air cleaner system, the pressure drop between the filter inlet and outlet is used under the rated air flow condition. In this study, the effect of sensor error in this air cleaner testing is experimentally carried out. It is found that the errors of the temperature sensor does not significantly affect the estimation of pressure drop. However, in the case of the pressure sensor, 5% sensor error results in the error of pressure drop estimation by 3%. Therefore, it is recommended that the measurement accuracy of the pressure sensor mounted in test system should be maintained at less than 5%.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.14-20
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• 2018

An estimation law of air mass flow rate for high speed engine control is presented. The variables of mass estimation equations are modified to measurable variables which can be obtained during flight, and the effectiveness of each variable to the estimation accuracy is evaluated. The equation is modified to a simplified form, and the uncertainty is evaluated. In addition, reference data for the selection of estimation methods is suggested by considering the sensitivity analysis of sensor error.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.257-258
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• 2007

이 논문에서는 자동차 공기청정기의 성능을 테스트하기 위한 자동화 시험 장치를 설계 및 구현하였다. 기존의 수동시험장치의 경우 정확한 유량 조절이 불가능하여 성능시험평가결과에 오차가 크고 시험과정이 불편하였다. 본 논문에서는 신뢰성 높고, 자동제어가 가능한 시스템을 설계하기 위하여 유량센서, 압력센서, 온도 센서, 습도 센서들의 데이터를 데이터 수집 장치를 통해 수집하고, 컴퓨터 기반의 제어 및 계측 프로그램인 LabVIEW를 이용하여 제어 및 모니터링 프로그램을 제작하였다. 그래픽 기반의 LabVIEW를 이용함으로써, 사용자에게 편리한 인터페이스를 제공하고, 기존의 수동 시스템보다 정확한 성능테스트 데이터를 제공함으로써, 에어필터의 품질향상이 되도록 하기 위한 성능 테스트 장치를 제작한다.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.268-273
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• 2000

This paper represents a hot-film flow sensor which is compensated by a noble temperature compensation method using the initial unbalanced voltage. The resistance value of the sensor is determined by using the graph of the initial unbalanced voltage of an open-loop circuit against the air temperature. The compensation is accomplished by applying the unbalanced ratio of the resistors in the Wheastone bridge circuit. In the range of air temperature of $-20^{\circ}C{\sim}120^{\circ}C$, the error is about ${\pm}1%$.

• The Journal of the Acoustical Society of Korea
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• v.42 no.1
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• pp.7-15
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• 2023

Recently, as interest in air quality in vehicles increases, the use of fine dust detection sensors for air quality measurement is becoming common. An axial-flow fan is inserted in the fine dust sensor installed in the air conditioning system in the vehicle to prevent dust from sinking directly on the sensor. When the sensor operates, the flow noise caused by the rotation of the axial-flow fan acts as a major noise source of the fine dust sensor. flow noise is recognized as one of the product competitiveness of fine dust sensors. In this study, the noise was gradually reduced at the same flow rate by improving the flow performance of the small axial flow fan. First, a virtual fan performance tester consisting of about 20 million grids was developed to analyze the aerodynamic performance of the target small axial-flow fan. In addition, the flow field was simulated by using compressible Large Eddy Simulation for direct computation of flow noise as well as high-accurate prediction of flow rate. The validity of numerical method are confirmed through the comparison of predicted results with experimental ones. After the effects of pitch angle on flow performance were analyzed using the verified numerical method, the pitch angle was determined to maximize the flow rate. It was found that the flow rate was increased by 8.1 % and noise was reduced by 0.8 dBA when the axial-flow fan with the optimum pitch angle was used.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.165-165
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• 1999