• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.301-307
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• 2011

Turbo blowers are mainly used in refuse collection systems. We discuss blower performance in relation to the angle of the inlet vane installed at the upstream of the blower. The flow characteristics of the components are analyzed by three-dimensional Navier-Stokes analysis and compared to experimental results. A two-stage serially connected turbo blower is introduced to analyze the performance experimentally. Throughout the experimental measurements and the numerical simulation, the distorted inlet velocity generated in the small vane angle reduces the performance of the blower, because of the local leading-edge separation and the resulting non-uniform blade loading. We also perform a detailed flow analysis using the results obtained in the numerical simulation.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.426-430
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• 2012

본 연구에서는 3차원 수치 해석 기법으로 SDR 반응기 내 유동 특성을 모사하여 유동 분포 및 체류 시간등을 확인하고 혼합 특성 개선을 위한 방법에 대해 연구하였다. 본 연구 대상 SDR 반응기는 입구 덕트와 반응기 본체의 접속 구간에 가이드 베인(Guide vane)이 설치되어 있고 그 바로 하부 지점에 흡수제를 분무하는 노즐이 설치되어 있다. 이는 처리가스가 반응기로 유입될 때 가이드 베인에 의해 선회류를 형성하여 분무된 흡수제와의 혼합을 촉진시키기 위한 목적으로 설치하였다. 시간당 1,971$m^3/min$ at $260^{\circ}C$의 처리가스가 반응기 상부로 유입되어 가이드 베인을 거쳐 선회류를 형성한 후흡수제와 혼합되어 하부로 배출되는 구조이다. 유동 특성을 분석한 결과, 처리가스가 반응기 중앙으로 강하게 편중되고 있었으며 반응기 양 측면으로 부상 기류가 형성되고 있음을 확인할 수 있다. 또한 강한 편류에 의해 체류시간도 매우 짧은 것으로 판단되는 바, 가이드 베인의 기류 안내 각도가 적합하지 못함을 확인할 수 있었다. 이는 곧 혼합 특성 저하에 따른 미반응 액적의 다량 발생과 함께 고착에 의한 스케일 형성 가능성이 매우 클 것으로 예상되므로 혼합 특성을 개선할 수 있는 설계 변경이 필요할 것으로 판단되었다. 따라서 편류를 해소하고 노즐 근처에서의 체공시간을 확보할 수 있도록 가이드 베인의 안내 각도를 더 크게 변경한 결과, 기존 설계상에서 본체 중앙에 형성되는 편류가 해소되고 선회류의 전개 각도가 커지면서 체류시간 역시 약 5초 이상으로 유지되고 있음을 확인할 수 있었다. 따라서 가이드 베인의 각도만 변경하더라도 본체 형상의 추가적인 변경없이 유동의 혼합 특성을 개선시킬 수 있을 것으로 판단되었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.225-232
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• 2017

Several maintenance issues related to cavitation erosion and fatigue cracks in the water turbine subcomponents of pumped-storage plants, such as a runner and a draft tube, have been reported in the past. Generally, the pumped-storage plants provide ancillary services, such as black-start and system stabilization. The ancillary services are responsible for cyclic low opening operation of the guide vanes. It has been empirically established that this low opening operation further damages the water turbine subcomponents. In this study, the acceleration effect of the low opening operation on the cavitation erosion and fatigue of the water turbine is quantitatively assessed through finite element flow analysis, finite element stress analysis, and fatigue analysis. As a result of the assessment, it is identified that the cavitation potential increases and the turbine efficiency decreases with a decrease in the opening of the guide vane. Also, the low opening operation has an insignificant effect on the fatigue even though it increases the maximum stress values at the runner blade roots.

• The Korean Journal of Food And Nutrition
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• v.27 no.3
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• pp.400-405
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• 2014

Recently, cases of Aloe vera induced-toxic hepatitis have been reported. However, the precise inflammatory effects of Aloe vera extract have not been clearly elucidated yet. In this study, the inflammatory effects and the mechanism of 70% ethanolic Aloe vera extract on liver were evaluated by in vitro assays using human hepatoma HepG2 cells. Cell viability was investigated using MTT assay at $0.001{\sim}100{\mu}g/mL$ of Aloe vera extract. To evaluate inflammatory effect of the Aloe vera extract, the secretion of pro-inflammatory cytokine Interleukin 8 (IL-8) and Macrophage colony-stimulating factor (M-CSF) were detected. Aloe vera extract did not induce cell death at concentrations of $0.001{\sim}100{\mu}g/mL$. However, Aloe vera extract significantly increased the IL-8 secretion by 15.7~25.8% and the M-CSF secretion by 36.6~61.5% at the same concentrations. These results indicate that Aloe vera extract shows an inflammation-related mild hepatotoxicity than a severe toxicity such as cell death and this hepatitis is mediated by the secretion of inflammatory cytokine IL-8 and M-CSF.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.35-43
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• 2019

In this study, a guide vane with varying positions and incidence angles was adopted to a pin-fin channel to analyze the change in thermal performance and pressure loss characteristics. A numerical analysis was conducted to investigate the effect of incidence angles and positions on heat transfer and flow characteristics at Re =1400. The results of it were compared those of a pin-fin channel without a guide vane. In case 1 when the incidence angle is $0^{\circ}$, the heat transfer performance is maximized and improved by approximately 5% when compared to the pin-fin channel without the guide vane. In case 2 when the incidence angle is $10^{\circ}$, the pressure loss is minimized and decreased by approximately 1.9% when compared to the pin-fin channel without the guide vane.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.06d
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• pp.125-130
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• 1998

• Journal of the Korean Professional Engineers Association
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• v.43 no.4
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• pp.12-14
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• 2010

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.7-13
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• 2015

In this study, we developed a gear-type vane damper which replaces the link type through a proper gear design by means of a finite element analysis. We analyzed the fluid flow according to the amount of angular displacement. torque and backlash problems were addressed in conjunction with the pinion as a structural improvement of the forced draft fan (FD FAN). Through an environmental test. Also, results nearly identical to those in the test could be drawn when using a numerical method. Finally, we compared the gear driving result with simulation results. objective of the present study is to identify a nonlinear flow rate control method for a gear-type vane damper and to propose a damper shape which offers linear flow rate control. This study is related to the development of a gear-type vane damper of the change-link type in a forced draft fan.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.134-139
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• 2010

In this study, we developed the gear type vane damper replacing the link type through gear design using Finite Element Analysis(FEA). FEA about the pinion and the vane shaft in the boss of gear type damper for quality improvement was accomplished. We analyzed fluid flow according to angular displacement. Catched the problem of the torque and backlash bring to the pinion as structure improvement of the forced draft fan(FD FAN). Finally, we compared the gear driving result with simulation. It is the objective of the present study to identify a nonlinear flow rate control of gear type vane damper and to suggest a damper shape with a linear flow rate control. This study is related to the development of gear type vane damper change link type in forced draft fan.

• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.46-50
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• 2012

A high-speed centrifugal pump requires more attention to the control of its axial thrust due to the high discharge pressure than a conventional industrial pump. Vanes employed toward the rear cavity of the impeller can be an effective device to control the axial thrust of the pump. The vanes disturb circumferential flow of the cavity and it can modify the axial force acting on the impeller. In this paper, three types of vanes are installed in the high-speed centrifugal pump for liquid rocket engines and the thrust of the pump is measured with an additional thrust measurement unit. According to the results, shapes of cavity vanes have effects on the axial thrust of the pump. As the height of vanes increases, the outlet pressure of the rear floating ring seal decreases which results in a decrease of the thrust. On the other hand, head of the pump is almost same regardless of cavity vanes. Also, the pressure drop of the bypass pipeline increases when vanes are removed.