• Steel and Composite Structures
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• 제42권3호
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• pp.397-405
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• 2022

The existing researches on the dynamics of the fluid-conveying pipes only focus on stability and vibration problems, and there is no literature report on the wave propagation of the fluid-conveying pipes. Therefore, the purpose of this paper is to explore the propagation characteristics of longitudinal and flexural waves in the fluid-conveying pipes. First, it is assumed that the material properties of the fluid-conveying pipes vary based on a power function of the thickness. In addition, it is assumed that the material properties of both the fluid and the pipes are closely depended on temperature. Using the Euler-Bernoulli beam equation and based on the linear theory, the motion equations considering the thermal-mechanical-fluid coupling is derived. Then, the exact expressions of phase velocity and group velocity of longitudinal waves and bending waves in the fluid-conveying pipes are obtained by using the eigenvalue method. In addition, we also studied the free vibration frequency characteristics of the fluid-conveying pipes. In the numerical analysis, we successively studied the influence of temperature, functional gradient index and liquid velocity on the wave propagation and vibration problems. It is found that the temperature and functional gradient exponent decrease the phase and group velocities, on the contrary, the liquid flow velocity increases the phase and group velocities. However, for vibration problems, temperature, functional gradient exponent parameter, and fluid velocity all reduce the natural frequency.

• 한국항공우주학회지
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• 제37권5호
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• pp.450-456
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• 2009

수동형 진동제어 방식과 같이 시스템이 안정되며, 수동형에 비해 높은 제진 효과가 기대되는 반능동 진동제어 방식은 시스템의 안정화가 요구되는 우주구조물의 제진방법에 유효한 진동제어 방식중 하나이다. 본 논문에서는 유연우주트러스구조물의 진동제어를 위해 고안된 반능동 댐퍼내 작동유체의 질량을 모델링에 고려했을 경우의 제진특성을 분석하였고 댐퍼내 작동유체의 점성이 부족감쇠를 유지 할 경우, 작동유체 질량 적용에 따른 반능동 댐퍼의 제진효과를 확인하였으며 이를 토대로 반능동 댐퍼의 성능향상을 위한 설계방법을 제시하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.313-317
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• 2001

Magneto-Rheological fluid (MR fluid) is known as a class of functional fluid with controllable apparent viscosity of the fluid by the applied magnetic field strength. Extensive researches with the functional fluids have been done on applications of the fluid to mechanical components such as suspension, absorber, engine mount, clutch, break, valve, etc. In this study, a new torsional damper using MR fluid is proposed, and the response property of the damper was theoretically investigated. The present damper is quit effective for reducing the driveline vibration in a wide range of the engine speed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.67-70
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• 2002

This paper presents the property of the Squeeze Film Damper (SFD) using Magneto-Rheological fluid (MR fluid). The damping property of a SFD for a flexible rotor system varied according to vibration mode. MR fluid is known as a functional fluid with controllable apparent viscosity of the fluid by applied magnetic field strength. When the MR fluid is applied in the SFD, the SFD using MR fluid can effectively reduce vibrations of the flexible rotor in a wide range of rotating speed by control of the applied magnetic field strength. To investigate in detail the SFD using MR fluid, the SFD to support one mass was constructed and its performance was experimentally investigated in the present study. The damping property of the SFD using MR fluid has viscous damping by Newtonian fluid, but not Coulomb friction by Bingham fluid. Therefore, The system damped by the SFD can be considered as a linear system.

• KSBB Journal
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• 제23권2호
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• pp.147-152
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• 2008

다양한 기능성을 갖는 식물체를 대상으로 새로운 천연 식품보존제 및 방부제 개발의 일환으로 다양한 방법으로 추출한 항균환성 물질을 몇 종의 병원성균과 식중독균, 효모, 곰팡이 등 10개 균주에 대하여 항균활성 검색을 하였다. 각 추출방법에 따른 추출 수율을 보면 편백과 육계 초임계 추출물의 수율이 가장 높았지만, 오레가노와 황금의 경우에는 초임계 추출물의 수율이 가장 낮았다. 그러나 항균활성 실험에서 disc-diffusion method 및 최소억제농도 (MIC) 실험 결과 유기용매 추출 및 열수 추출보다 초임계 추출의 경우가 항균활성이 모든 시료에서 높은 것으로 나타났다. Disc-diffusion method에서 육계 초임계 추출물의 경우 에탄올 추출물보다 항균활성이 두 배정도 높게 나타났고, 10개 균주에 대해 모두 항균활성을 나타냈다. 황금 초임계 추출물은 L. monocytogenes에 강한 항균활성을 보였고, 오레가노와 편백의 초임계 추출물은 S. typhimurium에 강한 항균활성을 보였다. 최소억제농도 (MIC)에서는 편백 초임계 추출물이 다른 초임계 추출물에 비해 강한 항균활성을 보였으며, 그 다음으로 육계, 황금, 오레가노 초임계 추출물의 순으로 항균활성을 나타내었다. 따라서 천연물을 이용한 항균제 개발에 있어 초임계 추출방법이 항균력이 높은 기능성 성분을 추출해 내는데 가장 효과적인 추출방법인 것으로 판단된다.

• 유공압시스템학회논문집
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• 제8권4호
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• pp.1-8
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• 2011

Injection molding machine is the assembly of many kinds of mechanical and fluid power part and electro-electronic control system. From in these, fluid power is a part where becomes the first core of this machine. Fluid power systems of injection molding machine are modelled and analyzed using a commercial program AMESim. The analysis model which is detailed about the parts applied a publishing catalog data. Sub system models which is divided according to functional operation are made and its analysis results shows how design parameters work on operational characteristics like displacement, pressure, flow rates at each node and so on. Total fluid power circuit model is also made and analyzed. The results made by analysis will be used design of fluid power circuit of injection molding machine.

• Smart Structures and Systems
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• 제18권5호
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• pp.865-884
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• 2016

We have previously demonstrated a microfluidic elastomer, which changes apparent color and could have potential applications in smart windows. The practical use of such functional microfluidic systems requires rapid and uniform fluid displacement throughout the channel network with minimal amount of liquid supply. The goal of this simulation study is to design various microfluidic networks for similar applications including, but not limited to, the color-switching windows and compare the liquid displacement speed and efficiency of the designs. We numerically simulate and analyze the liquid displacement in the microfluidic networks with serpentine, parallel and lattice channel configurations, as well as their modified versions with wide or tapered distributor and collector channels. The data are analyzed on the basis of numerical criteria defined to evaluate the performance of the corresponding functional systems. We found that the lattice channel network geometry with the tapered distributors and collectors provides most rapid and uniform fluid displacement with minimum liquid waste. The simulation results could give an important guideline for efficient liquid supply/displacement in emerging functional systems with embedded microfluidic networks.

• 감성과학
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• 제10권3호
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• pp.367-372
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• 2007

본 연구에서는 유체시스템을 이용한 나일론 필라멘트의 실크감성화 기술을 연구하였다. 이를 위해서 타스란 텍스쳐링 ATY 기계를 개조하였으며, 4가지의 40d/12f 나일론 소재가 개조된 ATY기계에서 기능성 약제를 이용하여 만들어졌다. 이들 소재사를 사용하여 4가지 직물이 제조되어 염색 가공 공정을 진행시켰다. 그리고 이들 직물시료의 수분율, UV차단성, 직물태등과 같은 여러 가지 물성을 측정하였으며, 이들 물성을 ATY텍스쳐링 조건과 기능제 처리조건과 비교 분석하였다.

• 동의생리병리학회지
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• 제31권1호
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• pp.1-7
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• 2017

There are two kinds of body fluid metabolism in Traditional Korean Medicine based on 'Internal Classic'("內經"); one is metabolism of body fluid(津液) meaning metabolism of physiological substance, and another is metabolism of humor meaning a metabolic process that excretes waste out of the body. 'Phlegm-retained fluid'(痰飮) is a typical pathological condition caused by abnormal fluid metabolism in Traditional Korean Medicine. As a result of reviewing the literature on 'phlegm-retained fluid'(痰飮), the following facts were found; 'Phlegm-retained fluid'(痰飮) is formed by abnormal state of metabolism of body fluid(津液). In other words, because of the action of various etiologies, qi(氣) and body fluid(津液) metabolism can have abnormal conditions and these metabolic disorders cause formation of 'phlegm-retained fluid'(痰飮). Treatments for 'phlegm-retained fluid'(痰飮) include the following: Eliminating the causes of illness, recovery of metabolism of qi(氣) and body fluid(津液), and functional recovery of pancreas and kidney related to body fluid(津液) metabolism. These treatments are distinguished from promotion of sweating(發汗) and helping urination, the treatments for humor metabolism abnormality.

• 유공압시스템학회논문집
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• 제8권4호
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• pp.24-31
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• 2011

Double-color Injection molding machine is the assembly of many kinds of mechanical, fluid power part and electric electronic control system. From in these, fluid power is a part where becomes the first core of this machine. Fluid power systems of double-color injection molding machine are modelled and analyzed using a commercial program AMESim. Partial system models which is divided according to functional operation are made and its analysis results shows how design parameters work on operational characteristics like pressure, flow rates, displacement at each node and so on. Analysis modeling and compared the data which gets from experiment and the analysis result which has a reliability got data. The results made by analysis will be used design of fluid power circuit for developing a double-color injection molding machine.