Experiments on characteristic deformation and breakup behaviors of an immiscible drop in a screw channel flow / H. S. Jun in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 3 (09/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 3 (09/2004) . - p. 218-224 Titre : Experiments on characteristic deformation and breakup behaviors of an immiscible drop in a screw channel flow Type de document : texte imprimé Auteurs : H. S. Jun, Auteur ; W. R. Hwang, Auteur ; T. H. Kwon, Auteur Année de publication : 2004 Article en page(s) : p. 218-224 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Deformation and breakup mechanisms of an immiscible drop were investigated experimentally in a screw channel flow, which mimics the flow in the metering section of the single screw extruder. It was observed that the deformation/breakup mechanisms are far distinct from the well-known routes for the linear flow, mainly because of the complex flow history that can be characterized by the repetition of strong/weak shear, the continuously varying shear direction and the acceleration/deceleration. The experimental observations include: cometlike thread formation with the large bulbous head and the long narrow tail; the initiation of the breakup at the entrance of the low-shear zone; breakup by asymmetric end pinching; breakup by the growth of the capillary wave, propagating from the tail toward the head; monotonically decreasing droplet size distribution from the head to tail. The mechanism for the comet-like thread formation has been investigated by using the numerically obtained flow field. DOI : 10.3139/217.1833 En ligne : https://drive.google.com/file/d/1ZIZj_lwVKGtaKAyqcthh_hWk6mM9bqvT/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3103 [article]

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Injection molding technology for high speed optical disk / S. J. Park in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 285-290 Titre : Injection molding technology for high speed optical disk Type de document : texte imprimé Auteurs : S. J. Park, Auteur ; S. K. Kim, Auteur ; T. H. Kwon, Auteur ; K. H. Yoon, Auteur Année de publication : 2001 Article en page(s) : p. 285-290 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Recently great efforts have been made to increase the data access speed and the data storage density of the optical memory disks such as CD-ROM, DVD, ASMO disk, etc. In the viewpoint of increasing the data access speed of the optical disks, it is of great importance to characterize accurately the vibration phenomena of the rotating disk, which is related to the critical speed and the characteristics of the frequency response. In this paper, towards the goal of increasing the data access speed of the optical disks, we have proposed a novel method for improved characteristics of disk vibration without deteriorating any other specification for the optical memory disks such as geometrical and optical characteristics. A possible idea to improve the vibration characteristics of the optical disk is that the tensile initial stress in the radial direction is to be imposed within the optical disk on purpose. By the synergy effect from the residual (initial) tensile stress frozen within the optical disk combined with the stress induced by the centrifugal force occurring in rotating the optical disk, the stiffness of the disk would increase to have a stronger resistance to the disturbance resulting in increase of critical speed. With such a synergy effect in mind, modifications related to the optical disk substrate design, injection mold design and processing conditions of injection molding were presented and partially evaluated. The computer simulation and experiments indicate that the suggested ideas clearly improve the characteristics of disk vibration without deteriorating any other specification for the optical memory disks. Note de contenu : - FEASIBILITY STUDY I : VIBRATION CHARASTERISTICS OF THE OPTICAL DISKS : Modal frequencies and FRF characteristics - Disk rotating and critical speeds - Initial stress effects - FEASIBILITY STUDY II : INJECTION MOLDING OF THE OPTICAL DISK - EXPERIMENTAL VERIFICATIONS DOI : 10.3139/217.1644 En ligne : https://drive.google.com/file/d/1p4KUT-q5sMcDjZCf9ZLJRQcIALGoPh3t/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15912 [article]

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Numerical investigation of hot embossing filling characteristics / T. G Kang in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 3 (07/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 3 (07/2007) . - p. 266-275 Titre : Numerical investigation of hot embossing filling characteristics Type de document : texte imprimé Auteurs : T. G Kang, Auteur ; T. H. Kwon, Auteur Année de publication : 2007 Article en page(s) : p. 266-275 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In the present study, we aim to investigate the basic flow and filling characteristics in the hot embossing filling stage, which depend on the geometry and processing conditions. For this purpose, we have developed a numerical analysis to simulate hot embossing filling using the finite element method and verified the developed program using the existing experimental data. As s basic study to understand hot embossing filling we have chosen a simple rectangular cavity with repeating protruded parts as a computational domain. The filling pattern was found to be significantly influenced by the variation of thickness of polymer substrate for the same stamp geometry, thermal boundary condition, and the embossing time. Filling from the border of the cavity is clearly observed as the thickness of polymer substrate decreases under the equal wall temperature condition. As for the effect of unequal temperature at the stamp and solid base plate, we found that the filling pattern has been affected by the temperature difference between the two surfaces and embossing time. The localized uprising flow results from the thermal boundary condition and subsequent change in the effective thickness of polymer substrate having enough fluidity to deform. DOI : 10.3139/217.0029 En ligne : https://drive.google.com/file/d/18_gljCeF5uoghHt5Vi_r9Zqvut3lu39U/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2704 [article]

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Resonant and invariant advection in single-screw extrusion / W. R. Hwang in INTERNATIONAL POLYMER PROCESSING, Vol. XVII, N° 4 (12/2002)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVII, N° 4 (12/2002) . - p. 309-317 Titre : Resonant and invariant advection in single-screw extrusion Type de document : texte imprimé Auteurs : W. R. Hwang, Auteur ; T. H. Kwon, Auteur Année de publication : 2002 Article en page(s) : p. 309-317 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In this paper, we discussed how unmixed and well-mixed zones are determined by the practical design parameters of the Chaos Screw (CS) system for the single-screw extruder, e.g. the helix angle, the magnitude of adverse pressure gradient, and the fraction of no-barrier zone. The key concept is the frequency ratio distribution of the unperturbed system. Through the extensive three-dimensional numerical simulations with finite element methods and particle tracing techniques, successive creation and breakup of resonant orbits and KAM tori in terms of design parameters are presented. The results show that one can predict the spatial configuration of well-mixed and unmixed zones from the frequency ratio distribution and the amount of the perturbation strength. Finally, the exit time distributions caused by dynamical structures are discussed. Note de contenu : - MODELING : System - Frequency ratios - NUMERICAL ANALYSES : Numerical methods - Frequency ratio distribution - Overall structures - Four example cases - Longitudinal mixing and exit time distribution DOI : 10.3139/217.1710 En ligne : https://drive.google.com/file/d/1nN8xJRGclwO3jXKebPy5Ov67qO0M98mo/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16019 [article]

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