• 전기전자학회논문지
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• 제24권1호
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• pp.33-39
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• 2020

본 논문에서는 타이어의 물리적인 요소 중 하나인 압력정보를 이용해서 자동차의 하중 표출이 가능한 타이어 공기압 측정 기술을 사용한 차량의 적재중량 측정시스템 설계 기법을 제안한다. 제안된 기법은 하중 및 진동에 의한 노이즈 보정, 기체유량 보정, 데이터 믹서, 중량 환산 등의 4가지 과정으로 구성된다. 하중 및 진동에 의한 노이즈 보정에서는 외부충격 및 차량이 주행 중 발생하는 진동 등에 의해 타이어의 내부 압력이 상승하는 노이즈를 제거한다. 기체유량 보정 과정에서는 하중 및 진동에 의한 노이즈 보정 과정을 거친 데이터에 대하여 지면의 온도상승에 의해 타이어의 내부 압력이 상승하는 노이즈를 제거한다. 데이터 믹서 과정에서는 화물적재 시 타이어에 수직으로 전달이 되어 타이어의 압력변화에 따른 공차, 중차, 만차에 대한 하중과 압력 등을 분류하게 된다. 중량 환산 과정에서는 하중 및 진동에 의한 노이즈 보정 및 기체유량 보정을 거친 데이터를 사용하여 중량 환산 알고리즘을 통해 중량으로 표출된다. 중량 환산 알고리즘은 하중과 압력변화에 대한 선형 함수의 기울기인 중량 환산 Factor를 구하여 중량을 환산한다. 본 논문에서 제안된 타이어 공기압 측정 기술을 사용한 차량의 적재중량 측정 시스템의 정밀도를 평가하기 위해 자체적으로 테스트 베드를 구축하여 평가하였다. 하중 및 진동에 의한 노이즈 보정 결과와 기체 유량 데이터 보정 결과는 신뢰성 있는 결과를 나타내었다. 또한 중량 정밀도 반복 실험도 국내 업체 기준치인 90% 보다 우수한 중량 정밀도를 나타내었다.

• 대한통합의학회지
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• 제9권1호
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• pp.183-192
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• 2021

Purpose : The purpose of this study was to investigate the impact of postural correction training on pulmonary function on 28 college students suspected of turtle neck syndrome, and the following conclusions were obtained. Methods : Turtle neck syndrome suspicion 28 person were randomly divided into a posture training group (n = 14) and group that does not perform posture training (n = 14). Respiratory function was measured by SPIROVIT SP-1 and respiratory gas analyzer. The posture training group performed balloon blowing and stair climbing after 20 minutes of posture training, and the group without posture training carried out balloon blowing training and stair climbing. Five times a week and for two weeks. Results : 1. The comparison of the FVC before and after experiments caused by balloon blowing showed a higher level of effortful pulmonary function in the control group than in the experimental group. 2. Comparison of PEFs before and after the experiment by balloon blowing showed that the experimental group's peak flow rate was higher than that of the control group. 3. Comparison of the FIVC before and after experiments with balloon blowing showed that the comparison of the FIVC showed a higher level of effortless intake pulmonary function in the control group than in the experimental group. 4. The comparison of the maximum ventilation volume(VE) before and after the experimental gas measurement showed that the maximum ventilation rate of the experimental group was higher than that of the control group. 5. The comparison of pre-test and post-test heart rate(HR) by breath gas measurement showed that the heart rate of the control group was higher than that of the experimental group. Conclusion : the results of this study showed that postural correction training, balloon blowing training, and stair climbing could have a positive impact on improving pulmonary function. However, the two-week experiment conducted five times a week showed an increase in pulmonary function, but it was difficult to see the effect due to the short study period. Therefore, it is hoped that later studies will be conducted more systematically on the effects of breathing exercises on improving pulmonary function after post-postural correction training for patients with pulmonary function problems.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.273-279
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• 2008

The purpose of this study is not only to evaluate thermal performance but also to find the stress behavior of heat transfer tubes under the part load operation in Heat Recovery Steam Generator. Flow analysis was performed to know the behavior of exhaust gas from gas turbine and thermal performance was calculated using distribution of hot exhaust velocity. In addition, tubes temperature during operation were gathered from actual plant to verify the uneven flow distribution under part load operation. Stress analysis was performed using tubes temperature data gathered from actual plant under both part and full load operations to know the stress behavior of tubes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.430-435
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• 2001

This paper introduces a pressure correction method for microflow computation. Conventional CFD methods with no slip boundary condition fail to predict the rarefaction effect of the wall when simulating gas microflows in the slip-flow regime. Pressure correction method with an appropriate slip boundary condition is an efficient tool in analyzing microscale flows. The present unstructured SIMPLE algorithm adopts both the classical Maxwell boundary condition and Langmuir boundary condition proposed by Myong. The simulation results of microchannel flows show that the proposed method has an effective predictive capability for microscale flows.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.127-133
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• 2008

Since the 1960's, exhaust gas recirculation(EGR) has been used effectively in spark ignition(SI) engines to control the exhaust emissions of the oxides of nitrogen(NOx). The most important requirements for the application of EGR systems to conventional SI engines are controllable flow rate and good dynamic response. In order to evaluate the characteristics of the electronic EGR valve, a test bench which is consisted of blower, heater, air flow meter and driving unit for electronic EGR valve was set up to simulate engine operating conditions. During the tests, the valve actuation parameters were controlled and the valve lifts and flow rates were measured to infer the characteristics of EGR valve. The results confirmed the capabilities of mathematical analysis and it seems that the correction for the valve lift and potentiometer output is necessary to achieve precise control of EGR rates.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.1067-1070
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• 1999

Anesthesia gas to pour to patients affects the flow and volume as the pressure difference of an oxygen and an anesthesia gas. An anesthesia gas, being injurious and polluting an environment, must control the pressure of an oxygen gas because of being used by closing up tight. But a pressure sensor to use for measuring an oxygen gas appears other pressure as the characteristic and the error difference of elements to use for implementing an system. A medical machine such as an anesthesia ventilator must be accurate because of using for the person's body. So we intend to implement an system for a sensor pressure measurement not to be change regardless of an environment. This papers is the target that a sensor pressrue measurement to be changed in environment is equal to actual sensor pressure measurement. So an implemented system is using analog filter and digital filter to reduce a noise. And we are using auto-zeroing and calibration to correct a sensor pressure which is changed in environment. Through such a process we increase the accuracy and the confidence of an anesthesia ventilator by controlling the flow of an anesthesia gas.

• 항공우주기술
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• 제2권1호
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• pp.1-10
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• 2003

항공기용 가스터빈엔진에 대한 경제적인 시험 기법 개발을 위해 천이상태 성능 시험 결과로부터 정상상태 성능을 예측할 수 있는 방안을 모색했다. 천이상태 성능과 정상상태 성능이 서로 달라지는 현상의 원인을 동역학적 천이 효과, 열적 천이 효과, 공기역학적 천이 효과로 구분하고, 각각을 모델링해서 엔진의 천이상태 성능을 통해 정상상태 성능을 계산하는 보정 인자를 정량화했다. 먼저 천이상태 성능시험 시 나타나는 엔진 입ㆍ출구의 온도 변화가 엔진 성능에 미치는 영향을 보정했고, 그 후 도입된 보정 인자를 사용해 정상상태 성능을 예측했다. 이렇게 예측된 결과와 실제 정상상태 성능시험 결과를 비교한 결과, 연료 소모량의 차이 3.68% 이내로 정상상태 성능을 예측할 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.187-194
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• 2005

For the analysis of compressible multi-phase and real gas flows, characteristic form of Roe's Riemann solver was derived using real gas equation of state. It was extended to multi component reactive system considering variable specific heat. From this study, it is known that some correction should be made for the use of existing numerical algorithm. 1) Sonic speed and characteristic variable should be corrected with real gas effect. 2) Roe's average was applicable only with the assumption of constant properties. 3) Artificial damping term and characteristic variables should be corrected but their influences may not be significant.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2059-2063
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• 2008

When a thermocouple is placed in a high temperature gas-flow stream, the measured temperature could be biased from the true gas temperature due to a large radiation heat loss from a thermocouple surface to its surroundings. In this study, two thermocouples of unequal diameters with 1/8 inch and 1/16 inch are used to correct the radiation effect. The method is called the reduced radiation error (RRE). The preliminary test results show that the radiation and the sheath conduction cannot be negligible for the gas temperature measurement. To minimize the sheath conduction effect, all the thermocouples will have a grounded junction and 1/8 inch thermocouple will be replaced with 1 mm thermocouples. In addition, the computational fluid dynamics code analysis shows that there is a negligible temperature difference between the positions where the thermocouples were installed.

• 천문학논총
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• 제30권2호
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• pp.457-459
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• 2015

Observations show that the accretion flows in low-luminosity active galactic nuclei (LLAGNs) probably have a two-component structure with an inner hot, optically thin, advection dominated accretion flow (ADAF) and an outer truncated cool, optically thick accretion disk. As shown by Taam et al. (2012), within the framework of the disk evaporation model, the truncation radius as a function of mass accretion rate is strongly affected by including the magnetic field. We define the parameter ${\beta}$ as $p_m=B^2/8{\pi}=(1-{\beta})p_{tot}$, (where $p_{tot}=p_{gas}+p_m$, $p_{gas}$ is gas pressure and $p_m$ is magnetic pressure) to describe the strength of the magnetic field in accretion flows. It is found that an increase of the magnetic field (decreasing the value of ${\beta}$) results in a smaller truncation radius for the accretion disk. We calculate the emergent spectrum of an inner ADAF + an outer truncated accretion disk around a supermassive black hole by considering the effects of the magnetic field on the truncation radius of the accretion disk. By comparing with observations, we found that a weaker magnetic field (corresponding to a bigger value of ${\beta}$) is required to match the observed correlation between $L_{2-10keV}/L_{Edd}$ and the bolometric correction $k_{2-10keV}$, which is consistent with the physics of the accretion flow with a low mass accretion rate around a black hole.