• Journal of the Semiconductor & Display Technology
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• v.2 no.2
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• pp.9-15
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• 2003

This paper proposes a thickness measurement method of silicon-oxide and poly-silicon film deposited on 12" silicon wafer for spin etcher. Halogen lamp is used as a light source for generating a wide-band spectrum, which is guided and focused on the wafer surface through a optical fiber cable. Interference signal from the film is detected by optical sensor to determine the thickness of the film using spectrum analysis and several signal processing techniques including curve-fitting and adaptive filtering. Test wafers with three kinds of priori-known films, polysilicon(300 nm), silicon-oxide(500 nm) and silicon-oxide(600 nm), are measured while the wafer is spinning at 20 Hz and DI water flowing on the wafer surface. From experiment results the algorithm presented in the paper is proved to be effective with accuracy of maximum 0.8% error.rror.

• Fibers and Polymers
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• v.4 no.4
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• pp.210-214
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• 2003

Siloxylated polypropylene fibers composed of polypropylene (PP) and aluminosiloxane (AS) were prepared by melt blending followed by spinning. The effects of blend compositions on the thermal behaviors, surface and tensile properties of PP/AS blend fibers were investigated by DSC, WAXD, SEM, static honestometer, etc. The heat of fusion of PP/AS blends decreased with increasing AS contents. In addition, the peak intensity of PP/AS blends in X-ray diffraction patterns decreased with increasing AS contents. It was observed that the silicone molecules exist and well distribute on the surface of siloxylated polypropylene fibers. From the results of the half-life period measurements, the anti-static properties of PP fibers siloxylated with AS was found to be significantly modified.

• Advances in materials Research
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• v.4 no.4
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• pp.207-214
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• 2015

It has been reported in the technical literature that orotic acid can be used in order to induce improved crystallization of biodegradable and biocompatible polymers like poly(L-lactic acid), polyhydroxybutyrate and poly(hydroxybutyrate-co-hydroxyhexaonat). The expected advantage of the changed crystalline structure is a reinforcing effect of the polymers. A lot of papers reported about the application of inorganic and organic agents for acceleration of heterogeneous nucleation. This study reports on an attempt to use orotic acid as appropriate non-toxic nucleating agent for improving mechanical properties of isotactic polypropylene. Special attention is given to demonstrate the effect of nucleation in a typical melt spinning process in order to improve the mechanical properties. The effects were demonstrated using rheology, thermal analysis and tensile testing.

• Composites Research
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• v.35 no.3
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• pp.216-221
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• 2022

Recently, the worldwide demand for disposable masks has increased due to COVID-19 infections and severe air pollution. Personal masks should reduce breathe resistance while maintaining filtering performance. In this study, a solution blowing process is used to produce composite nanofiber filters to co-spin two polymers at once. The manufacture process of the various fiber diameter filter was designed, and the filtration performance and differential pressure of the prepared filter was investigated. Poly vinylidene fluoride-hexafluoropropylene (PVDF-HFP) and Polylactic acid (PLA) fibers were chosen to be entangled together in a layer with a diameter of 1.05 ㎛ and 0.33 ㎛. Composite nanofilters showed up to 87% filtration efficiency and 32 Pa differential pressure.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.362-365
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• 2022

최근 노동 집약적인 성격의 섬유 산업에서는 AI를 통해 공정에 들어가는 시간과 비용을 줄이고 품질을 최적화 하려는 시도를 하고 있다. 그러나 섬유 방사 공정은 데이터 수집에 필요한 비용이 크고 체계적인 데이터 처리 시스템이 부족하여 축적된 데이터양이 적다. 또 방사 목적에 따라 특정 변수 위주의 조합에 대한 데이터만을 우선적으로 수집하여 데이터 불균형이 발생하며, 물성 측정환경 차이로 인해 동일 방사조건에서 수집된 샘플 간에도 오차가 존재한다. 이러한 데이터 특성들을 고려하지 않고 AI 모델에 활용할 경우 과적합과 성능 저하 등의 문제가 발생할 수 있다. 따라서 본 논문에서는 물성 단위 및 허용오차를 고려한 이상치 처리 기법과 데이터 불균형 정도 및 물성과의 상관성을 고려한 오버샘플링 기법을 물성 예측 모델에 적용한다. 두 기법들을 모델에 적용한 결과 그렇지 않은 모델에 비해 물성 예측 오차와 방사 공정 데이터에 대한 모델의 적합도가 개선됨을 보인다.

• Archives of Metallurgy and Materials
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• v.63 no.3
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• pp.1497-1502
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• 2018

Macroporous silica fibers having spherical cavities were fabricated by electrospinning using the spinning solution prepared from the mixed dispersion of tetraethylorthosilicate (TEOS) and polystyrene nanospheres as precursor and sacrificial templates, respectively, by injection through metallic nozzle. By applying electric field, the electro-spun fibers obtained by evaporation-driven self-assembly were collected on flat substrate or rotating drum, followed by the removal of the templates by calcination. The sound absorption coefficient of the porous fibers was measured by impedance tube, and the measured value was larger than 0.9 at high frequency region of incident waves. The surface of the resulting fibers was modified using fluorine-containing silane coupling agent to produce superhydrophobic fibrous materials to prevent the infiltration of humidity.

• Textile Coloration and Finishing
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• v.20 no.2
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• pp.1-8
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• 2008

Regenerated composite fibers are prepared from solution(styela clava tunics /poly vinyl alchol) using N-methylmorpholine-N-oxide(NMMO)/water(87/13)(wt/wt) as a solvent by dry-wet spinning. The chemical cellulose (94%, ${\alpha}$-cellulose content) used for this study is extracted from styela clava tunics (SCT, Midduck), which are treated in chemical process and mechanical grinding. The structure and physical properties of regenerated composite fibers were investigated through IR-spetra, DSC, TGA and SEM. The optimal blend ratio of SCT/PVA for spinning solution was 70/30 and the total weight was 4% concentrations in NMMO/water solvent system. The fiber density, moisture contents and the degree of swelling were $1.5(g/cm^3)$ 10.2(%) and 365(%), respectively. The crystallinity index of composite fibers are decreased as the PVA contents increased. Thermal decomposition of composite fibers took place in two stages at around $250^{\circ}C$ and $550^{\circ}C$. The best thermal stability was obtained with 30% PVA contents.

• Polymer(Korea)
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• v.33 no.5
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• pp.429-434
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• 2009

In this study, electro spinning conditions for PMMA were studied. Namely, the ratio of DMF and THF and its maximum concentration were examined. Conductivity of the polymer solution containing silver nanoparticles and its effect on fiber diameter were also studied. As the results, the maximum concentration for the electro spinning of PMMA was found at 18 wt%, and the ratio of DMF/THF was 7:3. The diameter of nanofibers obtained was 100-400 nm when the PMMA solution containing 1000 ppm silver was electrospun. It was found, from TEM results, that silver nanoparticles were distributed on the edge of fibers and the resulting nanofiber mats showed a good antibacterial activity.

• Polymer(Korea)
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• v.24 no.5
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• pp.656-663
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• 2000

The Effects of thermal history during the melt spinning process on the mechanical properties and crystallinity of polylactic acid (PLLA) fibers have been studied. Thermal history applied on PLLA during the melt process caused the decrease of number-average molecular weights and this resulted in the lowering of orientation and crystallinity in PLLA fibers. As a result, the longer applied thermal history, the less tensile strength and modulus, and the higher elongation at break. It was also found that primary factor for controlling crystallinity of PLLA fiber was the stress induced crystallization while the thermal induced crystallization had a little effect on the crystallinity of PLLA fibers. However, the thermal induced crystallization turn out to be important in the crystallinity developed by annealing of PLLA fibers.

• The Korean Journal of Zoology
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• v.33 no.3
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• pp.354-364
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• 1990

The ultrastructure and silk formational process of the flagelliform glands, one of the capture thread producing organs in the orb web spider (Nephila clavata L. Koch), have been studied with electron microscope. A pair of flagelliform glands consist of three distinct regions: excretory duct, storage sac and convoluted tail. This gland is connected to the large spinning tube (spigot) of the posterior spinnerets with two pairs of aggregate glands, and showed a characteristic spigot structure called "triad". The excretory duct consists of three long segments surrounded by the same sheath of connective tissue. The distal duct near the spinning tube bears the electron lucent subcuticles which have the functions of water removal and orientation of the silk fiber, whereas the proximal duct near the sac contains the cuticule precursor transported through the intercellular space. Cytoplasms of the sac and tail regions have well developed rough endoplasmic reticulum and contain the round secretory granules commonly, but the electron densities and internal textures of the granules do not coincided. Adjacent epithelial cells are connected with the specialized septate junctions, and secretory granules accumulated at the apical pole are released to the lumen by the apocrine secretion.secretion.