• CDE review
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• v.21 no.1
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• pp.30-31
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• 2015

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.34-41
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• 2021

Interventional radiology and minimally invasive surgery both require a precisely shaped microcatheter. Microcatheters are manufactured using polymer extrusion processes with a die and puller. The manufacturing parameters and die geometry greatly influence the profile of the extrudate and designing dies using a trial-and-error process is expensive and requires a lot of time. Therefore, predicting the profile of the extrudate is important for manufacturing microcatheters. This study investigates the effects of die design and geometry on the profile of the extrudate. The profiles of the extrudate are predicted using ANSYS Polyflow with respect to the different die geometries. The outer and inner diameters and wall thickness of the predicted extrudate are compared to those of a target extrudate. The die swell of melt polymer and the effect of the pulling are both examined. Optimized die designs are suggested for manufacturing the target extrudate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.110-113
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• 2008

This study was performed to predict the shape of polymer extrusion product and to find the cause of defective products Experiments was performed to extrude the complex profile shape using PC/ABS composite resin with new profile die and cooling die. A finite element analysis for the Polymer Extrusion process considering the heat transfer and thermal deformation was also performed, and the result was compared with the experimental data. It is found that the predicted profile shape in F. E. M was similar to the experimental result and the thickness of extruded product was thin when the velocity of profile die outlet was slow than the velocity of production (2m/min).

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.184.1-184
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• 2003

• Polymer(Korea)
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• v.39 no.3
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• pp.475-479
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• 2015

Droplet distribution of LCP(Vectra 950) and PET blend by repeated extrusion was examined through morphology analysis. Repeated extrusion was respectively proceeded twice and three times with blending condition and droplet distribution of only once extrusion sample showed uniform shape. However, droplet size of twice and three times extrusion samples increased and it was confirmed that droplets were concentrated on the center of specimens. It is thought that this phenomena were due to the compatibility and viscoelastic behavior of LCP/PET blend. Finally, it is thought that fiber manufacturing of different diameter is possible from spinning of repeated extrusion LCP/PET blended chip under same spinning condition.

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.106-110
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• 1998

최근 용융방사섬유의 제조에 이용되고 있는 고속방사법은 높은 신장속도하에서 일어나는 배향결정화에 의한 섬유구조형성을 목적으로 하는 방사법으로, 방사선에서의 동력학은 폴리머의 열특성, 냉각거동 및 방사선상에서 작용하는 응력 등의 많은 인자에 의해 영향을 받는다. 복합섬유란 특수한 복합방사장치를 이용하여 두 개의 폴리머가 동시에 압출되어 하나의 필라멘트를 형성하도록 방사한 섬유로써 권축섬유, 열융착형섬유, 이형단면섬유, 전도성섬유, 초극세섬유 등 특수한 섬유의 제조에 이용되기 때문에 그 상업적 관심도가 크다[1].(중략)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.145-155
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• 2005

In this study, a finite element method program code which can be accomodate boundary conditions on the complex surfaces has been developed to simulate polymer extruder processes. The analysis method includes the fractional 4-step method for efficient computation time and compact usage of memory storage to solve the velocities and the pressure values from the Navier-Stokes equation. By using the developed program which was verified with simple Poiseuille flow mixture phenomena in single-and twin-screw extruder are analyzed. It is concluded that the proposed method resulte Poiseuille Poiseuille d in fair agreement with the exact solution of simple flow and the back flow near the entrance happens in single-screw model. It is identified that the location and values of maximum pressure in the twin screw extruder model. It is expected that the Velocity field found can be used to predict the degree of mixture in the extruder barrel.

• Polymer(Korea)
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• v.34 no.6
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• pp.579-587
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• 2010

To investigate the properties of PET films, PET films were extruded at various temperature above $T_m$ and quenched at $18^{\circ}C$ for amorphous sheet, and stretched along a direction defined as the machine direction (MD) with a transverse direction (TD) above $T_g$ at various stretching ratios and then annealed at various temperatures produced by SKC PET line. Thermal shrinkage of MD and TD increased with decreasing annealing temperature and extruding temperature, and increasing stretching ratio. The degree of crystallinity, density, heat of fusion (${\Delta}H$) and pre-melting point ($T_m'$) increased with increasing annealing temperature and extruding temperature. Number average molecular weight ($M_n$) and intrinsic viscosity decreased with increasing extruding temperature. Tensile strength and modulus increased with increasing stretching ratio, however decreased with increasing annealing temperature. Reflective index of both stretching and thickness direction increased with increasing stretching ratio and annealing temperature.

• Polymer(Korea)
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• v.29 no.2
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• pp.198-203
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• 2005

Melt extrusion foaming process for the preparation of poly(L-lactic acid) (PLLA) scaffolds was carried out and the effects of foaming conditions on the pore structure of PLLA scaffolds and their mechanical properties were investigated. The porosity and mechanical properties of fabricated scaffolds were compared with the scaffolds obtained from the salt leaching method as well. It was found that the optimum pore structure was achieved when the PLLA melt was kept in extruder for the maximum decomposition time of blowing agent. In order to maintain the proper scaffolds structure, the blowing agent content should be less than $10\;wt\%$. It can be concluded that melt extrusion foaming process allows for the production of scaffold having higher mechanical properties with reasonable pore size and open cell structure for hard tissue regeneration even though it has less porosity than scaffolds made by salt leaching process.

• KIPE Magazine
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• v.6 no.4
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• pp.21-26
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• 2001

HVDC Light는 300MW에 이르는 전력을 가지고 있는 아불 성형된 DC Cable과 Voltage Source 컨버터에 기반을 둔 가장 최근의 HVDC 기술이다. HVDC Light 컨버터는 IGBT(Insulated Gate bi-polar Transistor)와 유효전력과 무효전력 사이의 고속 컨트롤을 위한 PWM(펄스 폭 변조)의 기능을 가지고 있다. HVDC Light 케이블은 압출 성형된 폴리머의 절연을 가진 케이블이며 직류 전압을 위해 특별히 개조되었다. 전력 범위 내에서 HVDC Light 컨버터와 케이블은 지중 또는 해저 송전 등에서도 송전전력을 위해 훌륭하게 조합될 수 있었다. 본 원고는 실제의 케이스로부터 얻은 경험지식으로, HVDC Light 기술의 조합을 사용해 해결된 문제점을 소개하고, HVDC Light의 장점을 설명하였다.