• Nuclear Engineering and Technology
• /
• 제48권5호
• /
• pp.1264-1272
• /
• 2016

The accurate estimation of leak rate through cracks is crucial in applying the leak before break (LBB) concept to pipeline design in nuclear power plants. Because of its importance, several programs were developed based on the several proposed flow models, and used in nuclear power industries. As the flow models were developed for a homogeneous pipe material, however, some difficulties were encountered in estimating leak rates for bimaterial pipes. In this paper, a flow model is proposed to estimate leak rate in bimaterial pipes based on the modified Henry-Fauske flow model. In the new flow model, different crack morphology parameters can be considered in two parts of a flow path. In addition, based on the proposed flow model, a program was developed to estimate leak rate for a crack with linearly varying cross-sectional area. Using the program, leak rates were calculated for through-thickness cracks with constant or linearly varying cross-sectional areas in a bimaterial pipe. The leak rate results were then compared and discussed in comparison with the results for a homogeneous pipe. The effects of the crack morphology parameters and the variation in cross-sectional area on the leak rate were examined and discussed.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 추계학술대회 논문집
• /
• pp.736-738
• /
• 2014

The paper deals with the accuracy comparison between two kinds of ultrasonic paths for flow rate measurement. In the Z-path, two transducers are installed on the opposite side of each other on a pipe, and the ultrasonic waves generated of one transducer propagate and arrive at the other one only through refraction. In the V-path, two transducers are installed on one side of a pipe, and the ultrasonic waves reflected at the inner wall of the pipe are received. The backgrounds were established to select one path to fit the usage by considering the advantages and disadvantages.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2002년도 ICCAS
• /
• pp.101.3-101
• /
• 2002

Contents 1 Abstract- In the thermal power plant, there are six manipulated variables; main steam flow, feedwater flow, air flow, spray flow, fuel flow, and gas recirculation flow. Therefore, the thermal power plant control system is a multi-input and output system. In the control system, the main steam temperature typically is regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. Up to the present time, the PID controller has been used to operate this system. This paper focuses on the characteristic comparison of the PID controller, the modified 2-DOF PID Controller on the DCS, in order to design an optimal...

• 동력기계공학회지
• /
• 제14권5호
• /
• pp.71-75
• /
• 2010

Leak detection technology is a challenging research until nowadays, because it has wide and various applications in industry. Furthermore pneumatic component reliability test based on ISO requires air leakage measurement. The conventional measurement methods need a complex operation and the calibration of leak detector. Tracing the history of our study, we proposed a new method for measurement of leak flow rate using isothermal chamber. In this study, propose a simulation model of isothermal chamber by infinitesimal flow -rate, such as a leak flow-rate. The effectiveness of the proposed simulation model is proved by simulation and experimental results. Base on the comparison results, proposed simulation model is good agreement with experimental results.

• Journal of Mechanical Science and Technology
• /
• 제18권12호
• /
• pp.2258-2264
• /
• 2004

This article described the numerical investigation of shear-thinning blood flow characteristics when subjected to longitudinal and transverse vibrations and delineated the underlying mechanisms of the flow rate enhancements, respectively. In order to fully consider the mechanical vibrations of the capillary, a moving wall boundary condition was adopted. The present numerical results showed that the longitudinal vibration caused a significant increase of wall shear rates, which resulted in a decrease of viscosity and the subsequent increase of flow rates. However, the shear rate for the transverse vibration was slightly increased and the calculated flow rate was underestimated comparing with the previous experimental results.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2005년도 연구개발 발표회 논문집
• /
• pp.670-677
• /
• 2005

In this study, we analyzed the three dimensional unsteady flow field around the motor cooling fan using the unsteady lifting surface theory. We obtained the flow rate for various geometries of fan from the calculated results of velocity field. For the data of design parameter and rotating speed(rpm) of the fan, we can predict the flow rate of the motor cooling fan with thin thickness through numerical analysis without the experimental data of the free stream velocity which is a boundary condition of flow field. the numerical results showed the flow rate within 10% of error in comparison with experimental results. The radial fans, which are often used as internal motor fan were also investigated with the same procedure.

• 한국세라믹학회지
• /
• 제52권5호
• /
• pp.325-330
• /
• 2015

Performance of solid oxide fuel cells (SOFCs), in comparison with that under hydrogen fuel, were investigated under direct internal reforming conditions. Anode supported cells were fabricated with an Ni+YSZ anode, YSZ electrolyte, and LSM+YSZ cathode for the present work. Measurements of I-V curves and impedance were conducted with S/C (steam to carbon) ratio of ~ 2 at $800^{\circ}C$. The outlet gas was analyzed using gas chromatography under open circuit condition; the methane conversion rate was calculated and found to be ~ 90% in the case of low flow rate of methane and steam. Power density values were comparable for both cases (hydrogen fuel and internal steam reforming of methane), and in the latter case the cell performance was improved, with a decrease in the flow rate of methane with steam, because of the higher conversion rate. The present work indicates that the short-term performance of SOFCs with conventional Ni+YSZ anodes, in comparison with that under hydrogen fuel, is acceptable under internal reforming condition with the optimized fuel flow rate and S/C ratio.

• 설비공학논문집
• /
• 제15권10호
• /
• pp.843-851
• /
• 2003

The present paper studies the leakage flow model used in the performance prediction of a scroll compressor. Two leakage flow models, isentropic and Fanno flow model, are studied in detail. Their predictions are also compared with CFD solutions to check the validity as a leakage flow model. Comparison with CFD solutions shows that the isentropic flow model predicts excessive leakage flow rate, while the Fanno flow model shows acceptable agreement with CFD solutions. The excessive leakage flow rate by isentropic flow model results in under-prediction of the overall performance of a scroll compressor.

• 한국콘텐츠학회논문지
• /
• 제21권5호
• /
• pp.941-948
• /
• 2021

본 연구는 소극적 TV 시청 집단과 적극적 TV 시청 집단의 차이를 시청자의 거주지역의 특성을 중심으로 조사하였다. 플로우 이론과 사회비교 이론을 적용하여 드라마 스토리의 상류 계층 묘사 여부가 각 집단의 드라마 시청률에 미치는 영향력에 대해 살펴보았다. 2016년 2월부터 2019년 3월까지 방영된 드라마 중 상류 계층 묘사 스토리를 가진 것으로 평가되는 4개 드라마와 대조군의 4개 드라마를 선정하여 지역케이블 서비스 업체인 딜라이브 방송의 서울/경기 15개 권역 11만 가구를 대상으로 하는 권역별 평균 시청률 자료를 이용했다. 드라마 시청률에 영향을 미칠 수 있는 권역별 여성비율과 소득수준 등 변수들을 통제하고 분석한 결과 상류 사회 스토리를 담은 상류 계층 묘사 드라마는 적극적 시청 집단의 시청률에 긍정적 영향을 미치는 반면 소극적 시청 집단의 시청률에는 부정적 영향을 미치는 것으로 나타났다. 본 연구 결과는 시청자의 패턴에 따라 상류 계층을 묘사한 드라마 시청률에 미치는 상이한 영향력을 밝혔다는 점에서 의의를 갖는다.

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