• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.89-89
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• 2012

선행 연구에서는 m-Aramid와 p-Aramid의 Ring 방적사/Core 방적사 조건에 따른 방적사 물성에 대해서 연구하였는데, Ring 방적사의 혼용율, 스핀들 속도에 따른 물성 변화, Core 방적사의 공정특성에 따른 방적성, 피복성에 대해 연구를 하였다. 그 결과 Ring 방적사의 경우 m-Aramid의 혼용율이 증가할수록 사 강도는 증가하는 경향을 확인할 수 있었고, 스핀들 속도가 증가함에 따라서 불균제도 및 사결점이 다소 증가하였다. Core 방적사의 경우 Core에 p-Aramid를 사용했을 때 방적성과 피복성은 양호 하였지만, 강한 p-Aramid에 의해 톱 롤러코트의 마모가 되는 경향을 볼 수 있었다. 본 연구에서는 Ring 방적사/Core 방적사에 대해 좀더 구체적인 제조공정조건에 의한 물성 변화를 알아보았고, 좀더 다양한 섬유소재를 적용해서 제조하였다. Ring 방적사의 경우 p-Aramid 혼용율에 따른 실험을 하였는데, m-Aramid에 대한 p-Aramid의 혼용율을 0%, 5%, 10%, 20% 로 하여 Ne30을 제조하였으며, Core 방적사는 Core를 p-Aramid 200D로 하고 Sheath를 Cotton으로 하여 Core 공급속도비 (1.06, 1.10, 1.14), 연계수(T/M, 3.8, 4.0, 4.2), Sheath/Core 혼섬율(70/30, 60/40, 50/50)에 따라 제조하였다. 추가로 Core 방적사는 Sheath에 Cotton 대신 FR-Rayon과 선염 Cotton을 사용하여 각각 Sheath/Core 혼섬율 70/30의 비율로 방적사를 제조하여 다양한 소재에 따른 방적사의 물성을 측정하였다. 제조된 시험 원사들의 측정 물성은 번수(Ne), 균제도(U%), 사결점(IPI), 강력(cN), 신도(%), 비강도(cN/Tex) 등이며, 편직을 통해 편성물의 외관을 확인하였다. Ring 방적사의 경우 p-Aramid의 혼용율이 증가할수록 강도는 완만하게 증가한 반면, 신도는 급격하게 감소하였다. Cotton Core 방적사의 경우는 공급속도비가 높아질수록 균제도가 높아지는 것을 볼수 있었고, Core 공급속도비가 높아질수록 외관상 피복도는 높아진 것을 볼 수 있었다. 이렇게 연구된 Aramid 소재를 이용한 방적사 제조 공정조건변화에 따른 물성 및 피복도 결과는 기존 방적업체에서 Aramid를 이용한 방적사 제조시에 공정조건을 확보하는데 도움이 될 것이라 생각되며, 방적사 시제품 생산시에 발생할 수 있는 시행착오를 줄임으로써 시제품 제조를 위한 생산비용의 Loss를 절감할 수 있을 것으로 예상된다.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.1-5
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• 2012

$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ hollow fiber with o.d. 1.02 mm and i.d. 0.437 mm were fabricated by a phase-inversion spinning technique.The starting $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ precursor was synthesized by the polymerized complex method and then calcined at $900^{\circ}C$. As-prepared powder was dispersed in a polymer solution, and extruded as form of hollow fiber through a spinneret. Finallydense $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ hollow fiber membrane was obtained by sintering for 2 h at $1,080^{\circ}C$ for the application of oxygen separation. In addition, despite a very thin membrane with 0.58 mm, the BSCF hollow fiber membrane possessed a proper mechanical strength of 602.5 MPa.

• Membrane Journal
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• v.22 no.3
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• pp.224-233
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• 2012

To improve permeation performance of gas separation membrane, polysulfone hollow fiber membrane was prepared by wet-dry phase inversion method using Triton X-100 as non-ionic additive. And variation of gas permeation behavior by additive was investigated. Various spinning conditions such as air gap, concentration of polymer, dope tank temperature were controlled and these effects were studied. The morphology and gas permeation property of hollow fiber membranes were investigated using scanning electron microscope (SEM) and bubble flow meter respectively. We confirmed that the membranes added with Triton X-100 had a smooth external skin at various air gap length conditions. The macrovoids of these hollow fiber membranes were more developed with increase of air-gap from 4 to 90 cm and that induced higher permeance. The permeance of polysulfone membranes has the higher value at comparatively lower concentration polymer (30 wt% polysulfone) and lower concentration of additive (15 wt% Triton X-100). When temperature in dope tank was controlled, the membranes prepared at $100^{\circ}C$ showed low permeance because of volatilization of additive and solvent.

• Science of Emotion and Sensibility
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• v.15 no.1
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• pp.141-148
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• 2012

This study investigated the structural coloration and fabric hand of the caustic reduced fabrics for emotional garment using structural color yarns, which was spun by 37 alternating nylon and polyester layers capable of producing basic colors using biomimetic technology. The colorations of the three kinds of structural color yarns were confirmed using multi angle spectro-photometer, and their triangular cross sections composed with 37 alternating nylon and polyester layers were measured using SEM and were discussed with layer length in relation with coloration and spinning conditions were also set up. The apparent color difference and reflectance of the three kinds of fabrics with different density and weave pattern were analysed as ranging from 400nm to 700nm. The optimum fabric structural design which is made by warp and weft densities(194ends/in ${\times}$ 105picks/in) and caustic reduction condition by $100^{\circ}C$ temperature and 60minutes with NaOH, 20g/l solution were decided through analysis of the mechanical properties and fabric hands of these three kinds of fabrics treated with 3 kinds of the caustic reduction conditions. And it was shown that the rate of caustic reduction was increased from 13% to 23% with increasing temperature and time of caustic reduction. The extensibility, bending rigidity and shear modulus of caustic reduction treated fabrics were decreased by treatment of caustic reduction, on the other hand fabric compressibility was increased. And it was shown that the hand value of specimen number one which was treated with temperature $100^{\circ}C$ and time 60minute was the best and the hand of this fabric was better than that of Morpho $fabric^{(R)}$ made by Teijin co. Japan.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.559-564
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• 2019

Hierarchical $ZnCo_2O_4$ hollow nanofibers were prepared by electrospinning and subsequent heat-treatment process. The spinning solution containing polystyrene (PS) nanobeads was electrospun to nanofibers. During heat-treatment process, PS nanobeads in the composite were decomposed and therefore generated numerous pores uniformly in the structure, which facilitated the heat transfer and gas penetration into the structure. The resulting hierarchical $ZnCo_2O_4$ hollow nanofibers were applied as an anode material for lithium-ion batteries. The discharge capacity of the nanofibers was $815mA\;h\;g^{-1}$ ($646mA\;h\;cm^{-3}$) after the 300th cycle at a high current density of $1.0A\;g^{-1}$. However, $ZnCo_2O_4$ nanopowders showed the discharge capacity of $487mA\;h\;g^{-1}$ ($450mA\;h\;cm^{-3}$) after 300th cycle. The excellent lithium ion storage property of the hierarchical $ZnCo_2O_4$ hollow nanofibers was attributed to the synergetic effects of the hollow nanofiber structure and the $ZnCo_2O_4$ nanocrystals composing the shell. The hierarchical hollow nanofiber structure introduced in this study can be extended to various metal oxides for various applications, including energy storage.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.819-825
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• 2018

Porous nanofibers comprising hollow ${\alpha}-Fe_2O_3$ nanospheres were prepared by applying both template method and Kirkendall diffusion effect to electrospinning process. During heat-treatment processes, the solid Fe nano-metals formed by initial heat-treatment in the carbon matrix were converted into the hollow structured ${\alpha}-Fe_2O_3$ nanospheres. In particular, PS nanobeads added in the spinning solution were decomposed and formed numerous channels in the composite, which served as a good pathway for Kirkendall diffusion gas. The resulting porous nanofibers comprising hollow ${\alpha}-Fe_2O_3$ nanospheres were applied as an anode material for lithium-ion batteries. The discharge capacities of the nanofibers for the 30th cycle at a high current density of $1.0A\;g^{-1}$ was $776mA\;h\;g^{-1}$. The good lithium ion storage property was attributed to the synergetic effects of the hollow ${\alpha}-Fe_2O_3$ nanospheres and the interstitial nanovoids between the nanospheres. The synthetic method proposed in this study could be applied to the preparation of porous nanofibers comprising hollow nanospheres with various composition for various applications, including energy storage.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.37-44
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• 2011

The critical micelle concentration (CMC) of sorbitan laurate SP 20 surfactant in this paper was near $7.216{\times}10^{-4}mol/L$ and the surface tension at CMC was about 26.0 mN/m, which showed higher CMC and lower surface tension than those of octylphenol ethoxylate octylphenol ethoxylate (OPE) 10 surfactant. Dynamic surface tension measurement using a maximum bubble pressure tensiometer showed that the adsorption rate at the interface between air and surfactant solution was found to be slower with SP 20 surfactant, presumably due to a low mobility of SP 20 surfactant monomer. The contact angle of SP 20 surfactant solution was observed to decrease with an increase in surfactant concentration and showed a larger value than that of OPE 10 surfactant solution. Half-life time for foams generated with 1 wt% surfactant solution was also larger with SP 20 surfactant, which indicated higher foam stability with SP 20 surfactant. Dynamic behavior study reveals that the solubilization of n-decane oil was much lower with SP 20, which is in good agreement with experimental results of foam stability, contact angle and CMC. Dynamic interfacial tension measurement by a spinning drop tensiometer shows that interfacial tensions at equilibrium condition in both systems were almost the same but the time required to reach equilibrium was longer with SP 20.

• Korean Journal of Heritage: History & Science
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• v.48 no.2
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• pp.142-157
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• 2015

This study examines how traditional knowledge functions in the specific techniques to make pottery in terms of the traditional knowledge on the pottery techniques of Onggi potters. It focuses on how traditional pottery manufacturing skills are categorized and what aspects are observed with regard to the techniques. The pottery manufacturing process is divided into the preparation step of raw material, the molding step of pottery, and the final plasticity step. Each step involves unique traditional knowledge. The preparation step mainly comprises the knowledge on different kinds of mud. The knowledge is about the colors and properties of mud, the information on the regional distribution of quality mud, and the techniques to optimize mud for pottery manufacturing. The molding step mainly involves the structure and shape of spinning wheels, the techniques to accumulate mud, ways to use different kinds of tools, the techniques to dry processed pottery. The plasticity step involves the knowledge on kilns and the scheme to build kilns, the skills to stack pottery inside of the kilns, the knowledge on firewood and efficient ways of wood burning, the discrimination of different kinds of fire and the techniques to stoke the kilns. These different kinds of knowledge may be roughly divided into three categories : the preparation of raw material, molding, and plasticity. They are closely connected with one another, which is because it becomes difficult to manufacture quality pottery even with only one incorrect factor. The contents of knowledge involved in the manufacturing process of pottery focused are mainly about raw material, color, shape, distribution aspect, fusion point, durability, physical property, etc, which are all about science. They are rather obtained through the experimental learning process of apprenticeship, not through the official education. It is not easy to categorize the knowledge involved. Most of the knowledge can be understood in the category of ethnoscience. In terms of the UNESCO world heritage of intangible cultural assets, the knowledge is mainly about 'the knowledge on nature and universe'. Unique knowledge and skills are, however, identified in the molding step. They can be referred to 'body techniques', which unify the physical stance of potters, tools they employ, and the conceived pottery. Potters themselves find it difficult to articulate the knowledge. In case stated, it cannot be easily understood without the experience and knowledge on the field. From the preparation of raw material to the complete products, the techniques and traditional knowledge involved in the process of manufacturing pottery are closely connected, employing numerous categories and levels. Such an aspect can be referred to as a 'techniques chain'. Here the techniques mean not only the scientific techniques but also, in addition to the skills, the knowledge of various techniques and levels including habitual, unconscious behaviors of potters.