• Title/Summary/Keyword: retraction

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Transition of Rivulet Flow from Linear to Droplet Stream

  • Kim, Ho-Young;Kim, Jin-Ho;Kang, Byung-Ha;Lee, Seung-Chul;Lee, Jae-Heon
    • International Journal of Air-Conditioning and Refrigeration
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    • v.10 no.3
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    • pp.147-152
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    • 2002
  • When a liquid is supplied through a nozzle onto a relatively non-wetting inclined solid surface, a narrow rivulet forms. There exist several regimes of rivulet flow depending on various flow conditions. In this paper, the fundamental mechanism behind the transition of a linear rivulet to a droplet flow is investigated. The experiments show that the droplet flow emerges due to the necking of a liquid thread near the nozzle. Based on the observation, it is argued that when the retraction velocity of a liquid thread exceeds its axial velocity, the bifurcation of the liquid thread occurs, and this argument is experimentally verified.

A Study on Blood Coagulation and Bleeding Time under Electroacupuncture Anesthesia and Medicament Anesthesia in the Dog (개의 전침마취(電針麻醉)와 약물마취하(藥物麻醉下)에서 혈액응고(血液凝固) 및 출혈시간(出血時間)에 관한 비교실험(比較實驗))

  • Park, Hyung-seon;Suh, Doo-seok
    • Korean Journal of Veterinary Research
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    • v.28 no.1
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    • pp.193-198
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    • 1988
  • Blood coagulation time, bleeding time, clot retraction ability, thrombocytes counts and hematological values under electroacpuncture anesthesis and medicament anesthesia, using 10 mongrel dogs were compared. The results were summarized as follows: 1. Blood coagulation time under electroacupuncture anesthesia was shorter than that under medicament anesthesia (p<0.001). 2. Bleeding time under electroacupuncture anesthesia was shorter than that under medicament anesthesia (p<0.01). 3. Clot retraction ability under electroacupuncture anesthesia was better than that under medicament anesthesia (p<0.01). 4. Thrombocytes counts under electroacupuncture anesthesia was more increased than that under medicament anesthesia (p<0.05). 5. Erythrocytes counts, hematocrit values, hemnglobin contents and leukocytes counts were decreased (p<0.01) under medicament anesthesia in comparison with control group, but there was no significant difference under electroacupuncture anesthesia.

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A Study of Rivulet Flow on Inclined Surface (경사면에서의 리뷸릿 유동에 관한 연구)

  • Kim, Jin-Ho;Kim, Ho-Young;Lee, Jae-Heon
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.576-581
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    • 2001
  • When a liquid is supplied through a nozzle onto a relatively nonwetting inclined solid surface, a narrow rivulet forms. This work provides novel physical insights into the following phenomena in the rivulet flow that have not been well understood to date. Firstly, the fundamental mechanism behind the transition of a linear rivulet to a droplet flow is investigated. The experiments show that the droplet flow emerges due to the necking of a liquid thread near the nozzle. Based on the observation, it is argued that when the retraction velocity of a liquid thread exceeds its axial velocity, the bifurcation of the liquid thread occurs, and this argument is experimentally verified. Secondly, a discussion on the curved motion of a meandering rivulet is given. This study proposes the contact angle hysteresis as a primary origin of the centripetal force that enables the rivulet's curved motion A simple scaling analysis based on this assumption predicts a radius of curvature which agrees with the experimental observation.

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CONVERGENCE OF APPROXIMATING FIXED POINTS FOR NONEXPANSIVE NONSELF-MAPPINGS IN BANACH SPACES

  • Jung, Jong-Soo;Park, Jong-Seo;Park, Eun-Hee
    • Communications of the Korean Mathematical Society
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    • v.12 no.2
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    • pp.275-285
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    • 1997
  • Let E be a uniformly convex Banach space with a uniformly G$\hat{a}teaux differentiable norm, C a nonempty closed convex subset of $E, T : C \to E$ a nonexpansive mapping, and Q a sunny nonexpansive retraction of E onto C. For $u \in C$ and $t \in (0,1)$, let $x_t$ be a unique fixed point of a contraction $R_t : C \to C$, defined by $R_tx = Q(tTx + (1-t)u), x \in C$. It is proved that if ${x_t}$ is bounded, then the strong $lim_{t\to1}x_t$ exists and belongs to the fixed point set of T. Furthermore, the strong convergence of ${x_t}$ in a reflexive and strictly convex Banach space with a uniformly G$\hat{a}$teaux differentiable norm is also given in case that the fixed point set of T is nonempty.

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CONVERGENCE OF VISCOSITY APPROXIMATIONS TO FIXED POINTS OF NONEXPANSIVE NONSELF-MAPPINGS IN BANACH SPACES

  • Jung, Jong-Soo
    • East Asian mathematical journal
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    • v.24 no.1
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    • pp.81-95
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    • 2008
  • Let E be a uniformly convex Banach space with a uniformly $G{\hat{a}}teaux$ differentiable norm, C a nonempty closed convex subset of E, and $T\;:\;C\;{\rightarrow}\;E$ a nonexpansive mapping satisfying the weak inwardness condition. Assume that every weakly compact convex subset of E has the fixed point property. For $f\;:\;C\;{\rightarrow}\;C$ a contraction and $t\;{\in}\;(0,\;1)$, let $x_t$ be a unique fixed point of a contraction $T_t\;:\;C\;{\rightarrow}\;E$, defined by $T_tx\;=\;tf(x)\;+\;(1\;-\;t)Tx$, $x\;{\in}\;C$. It is proved that if {$x_t$} is bounded, then $x_t$ converges to a fixed point of T, which is the unique solution of certain variational inequality. Moreover, the strong convergence of other implicit and explicit iterative schemes involving the sunny nonexpansive retraction is also given in a reflexive and strictly convex Banach space with a uniformly $G{\hat{a}}teaux$ differentiable norm.

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Design and Performance Evaluation of Retraction-Type Actuators with Displacement Amplification Mechanism Based on Thermomechanical Metamaterial

  • Cho, Yelin;Lee, Euntaek;Kim, Yongdae
    • Journal of Aerospace System Engineering
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    • v.14 no.2
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    • pp.28-35
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    • 2020
  • In this paper, we present a design for a retraction-type actuator (ReACT) that has the characteristics of both thermomechanical metamaterials and displacement amplification mechanisms. The ReACT consists of an actuating bar, a diamond-shaped displacement amplification (DA) structure, and a slot for loading thin-film heaters formed through the actuating bar. When power is supplied to the thin film heater, the actuating bars contacting the heater thermally expand, and the diamond-shaped DA structures retract in the longitudinal direction. The performance characteristics of the ReACT, such as temperature distribution and retracting displacement, were calculated with thermomechanical analysis methods using the finite element method (FEM). Subsequently, the ReACTs were fabricated using a polymer-based 3D printer that can easily execute complex structures, and the performance of the ReACT was evaluated through repeated tests under various temperature conditions. The results of the performance evaluation were compared with the results of the FEM analysis.

A Study of Rivulet Flow on an Inclined Solid Surface (경사면에서의 리뷸릿 유동에 관한 연구)

  • 김진호;김호영;강병하;이재헌
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.10
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    • pp.1042-1048
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    • 2001
  • When a liquid is supplied through a nozzle onto a relatively non-wetting inclined solid surface, a narrow rivulet forms. This work provides novel physical insights into the following phenomena in the rivulet flow that have not been well understood to date. Firstly, the fundamental mechanism behind the transition of a linear rivulet to a droplet flow is investigated. The experiments show that the droplet flow emerges due to the necking of a liquid thread near the nozzle. Based on the observation, it is argued that when the axial velocity of a liquid is slower than the retraction velocity of its thread, the bifurcation of the liquid thread occurs, and this argument is experimentally verified. Secondly, a discussion on the curled motion of a meandering rivulet is given. This study proposes the contact angle hysteresis as a primary origin of the centripetal force that enables the rivulet\`s curved motion. A simple scaling analysis based on this assumption predicts a radius of curvature which agrees with the experimental observation.

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