• Elastomers and Composites
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• v.41 no.4
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• pp.223-230
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• 2006

Rubber compounds have a high viscoelastic property. One of the viscoelastic behaviors during profile extrusion is the swelling of extrudate, and the amount of swelling varies with operational conditions in extrusion. It is well recognized that the elastic portion in the viscoelastic property plays an important role in the extrudate swell. In this study computer simulation of the die swell at the capillary die for several rubber compounds has been performed using commercial CFD code, Polyflow. A non-linear differential viscoelastic model, Phan-Thien-Tanner (PTT) model, was used in the computer simulation. Non-isothermal behavior was considered in the calculation. Distribution of pressure, velocity and temperature in the reservoir and capillary die, and extrudate profiles were predicted through the simulation. The amount of the die swell fur the different rubber compounds was investigated for various flow rates and three types of length to diameter of the capillary die. It is concluded that the PTT model successfully represented viscoelastic behavior of rubber compounds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.111-115
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• 2015

In injection molding process using hot runners, color change is a critical issue. This work proposes a method of assessing the color change characteristics of thermoplastics polymers. A method that utilizes a capillary die to measure degree of color change has been devised and implemented. The extrudate from the capillary die has been imaged and quantized to a gray scale value. Based on the gray scale value, the degree of color change has been determined. Under given temperatures and extrusion velocity, its trend along with the number of extrusion has been obtained and analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1023-1026
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• 2010

In this paper, rheological property of polymer blends in a confined geometry was investigated. The shear viscosity was measured in a capillary rheometer incorporated with a specially designed piston and three slit dies having 0.1, 0.2 and 0.5 mm in thickness. It was observed that the viscosity of polymer blends does not depend on the die size when the phase of polymer blends is a sea-island structure. However, when the phase of polymer blends is a co-continuous structure, the viscosity of the blends was dependent on the die size. By additional investigations, this result is attributed to the slip phenomenon between polymer phases in the blends.

• Elastomers and Composites
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• v.46 no.1
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• pp.54-59
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• 2011

One of the viscoelastic flow behaviors during profile extrusion is the swelling of extrudate. In this study, die swell of rubber compound in the capillary die have been investigated through experiment and computer simulation. Simplified viscoelastic model and non-linear differential viscoelastic model such as PTT model have been used in the computer simulation. The simulation results have been compared with experimental data. Experiment and simulation have been performed using fluidity tester and commercial CFD code, Polyflow respectively. Die swells predicted by two models showed good agreement with experimental results. Pressure and velocity distribution, and circulation flow at the corner of reservoir have been well predicted by PTT model. Simplified viscoelastic model can not predict circulation flow at the corner of reservoir. However this model has an advantage in computation time compare with full viscoelastic model, PTT model.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.101-101
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• 2019

비타민C가 많이 함유되어 있는 감귤류는 과육과 과피에 많은 영양성분을 함유하고 있다. 과육에는 비타민C, 각종 유기산, 비타민B복합체 등이 다량으로 함유되어 있고, 과피에는 펙틴과 비타민C, 베타카로틴 등이 함유되어 있어 암세포의 발달을 억제하고 생리활성물질로 피부노화를 지연시키며 미백효과를 가져다주고 있다. 또한 과피내의 '테레빈유'라는 기름성분으로 세포 노폐물의 배출을 양호하게 하여 다이어트와 복부비만을 억제하는데 좋은 효과가 있다고 알려져 있다. 이러한 감귤류는 다른 과수품종보다 비타민P, 비타민B군과 단백질 등이 많이 함유되어 있어 모세혈관을 보호하며 심혈관질환과 뇌졸중, 뇌출혈 등을 억제하는 효과를 가지고 있다고 보고되고 있다. 따라서 본 실험에서는 유자, 당유자, 청귤, 하귤, 병귤, 사두감, 레몬, 자몽, 오렌지 등의 과피와 과육 추출물로부터 항산화 활성을 조사하였던 바, 대부분의 감귤류에서 좋은 폴리페놀 함량을 보였으며 특히 과피에서 더 양호한 결과를 나타내었다. 이러한 결과들은 레몬, 자몽, 당유자, 유자, 청귤 등의 과피에서 과육보다 더 양호한 항산화 활성을 나타내었다. 이러한 결과들로 미루어 볼 때 감귤류 과육과 더불어서 과피에서도 매우 양호한 영양성분과 항산화 활성이 있다는 것을 확인 할 수 있었다.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.92-96
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• 2019

In the presence of ${\mu}-tip$ embedded in a slot-die head for stripe coatings, there arises the capillary flow that limits an increase of the stripe density, which is required for the potential applications in organic light-emitting diode displays. With an attempt to suppress it, we have employed a computational fluid dynamics software and performed simulations by varying the ${\mu}-tip$ length and the contact angles of the head lip and ${\mu}-tip$. We have first demonstrated that such a capillary flow phenomenon (a spread of solution along the head lip) observed experimentally can be reproduced by the computational fluid dynamics software. Through simulations, we have found that stronger capillary flow is observed in the hydrophilic head lip with a smaller contact angle and it is suppressed effectively as the contact angle increases. When the contact angle of the head lip increases from $16^{\circ}$ to $130^{\circ}$, the distance a solution can reach decreases sharply from $256{\mu}m$ to $44{\mu}m$. With increasing contact angle of the ${\mu}-tip$, however, the solution flow along the ${\mu}-tip$ is disturbed and thus the capillary flow phenomenon becomes more severe. If the ${\mu}-tip$ is long, the capillary flow also appears strong due to an increase of flow resistance (electronic-hydraulic analogy). It can be suppressed by reducing the ${\mu}-tip$ length, but not as effectively as reducing the contact angle of the head lip.

• Analytical Science and Technology
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• v.17 no.5
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• pp.393-400
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• 2004

Nitrosation of phenol (POH) was studied by adding hydrochloric acid and sodium nitrite to phenol solution with reaction temperature and time change. The optimum condition of nitrosation was found from the effects of hydrochloric acid and sodium nitrite concentration, reaction temperature, and reaction time changes on the production of nitrosophenol (POHNO). As a result, it was found that the optimum conditions were $5.0{\times}10^{-4}{\sim}2.0{\times}10^{-3}M$ range of $NO{_2}^-$ concentration, more than 0.10 M of HCl concentration, temperature of $80^{\circ}C$, and 3 hrs. of reaction time. In this condition, 10 U.S. E.P.A. classified priority environmental pollutant, phenols, were nitrosated. Nitrosated phenols were: POH, 2-Chlorophenol (2ClPOH), 2,4-diChlorophenol (2ClPOH), 2,4-dimethylphenol (24diMPOH), and 4-Chloro -3-methylphenol (4Cl3MPOH), and a small part of 2-nitrophenol (2NPOH). The ${\lambda}_{max}$ values of nitrosated phenols in acidic solution were around 300 nm, and those in basic solution were around 400 nm. Molar absorptivities (${\varepsilon}$) at the 400 nm of the nitrosated phenols in the basic solution were 1.5~2.0 times larger than those at 300 nm in acidic solution. It was also found by Capillary-HPLC chromatograms of the nitrosated phenol solutions that the production of the nitrosophenols were interfered by the excess concentration of nitrite (more than $3.0{\times}10^{-3}M$).