• 펄프종이기술
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• 제40권4호
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• pp.43-50
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• 2008

Adsorption of xylans extracted from birchwood and oat spelt on Hw-BKP were analyzed using HPLC. The effect of xylan adsorption on paper properties such as tensile, tear index and brightness was also investigated. The constituents of xylan was analyzed with HPLC after hydrolysis with dilute sulfuric acid. It was shown that xylose was the major constituent and small amounts of glucose and galactose were contained in the xylan samples. Adsorption of xylan on hardwood fibers was evaluated using acid hydrolysis and HPLC techniques. Results showed that the adsorption of negatively charged xylan on the fiber surface was negligible probably because electrostatic repulsion between these two materials. Pretreatment of the fiber with alum increased xylan adsorption. The amount of adsorption increased up to 30 mg/g. With the increase of xylan adsorption both tensile and tear strength of the handsheet increased suggesting xylan can be a very effective strength agents for papermaking. Brightness of the handsheets decreased, however, with the use of xylan.

• 펄프종이기술
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• 제46권6호
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• pp.50-55
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• 2014

An oxidized starch was modified for surface sizing via etherification and esterification. Propylene oxide (PO), sodium monochloroacetate (SMCA), and acrylonitrile (AN) were used as etherification, and vinyl acetate monomer (VAM), maleic anhydride (MA), fumaric acid (FA), and itaconic acid (ITA) were used for esterification. Esterification and etherification of starch decreased both Brookfield viscosity and Brabender viscosity substantially even though the solids level was increased by 2% from 14 to 16%. Surface sizing performance of starches in tensile strength, stiffness and compressive strength was improved by esterification and etherification of the oxidized starch. Especially, SMCA etherification was found to be the most effective modification method.

• 한국염색가공학회지
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• 제26권1호
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• pp.32-38
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• 2014

There has been increasing demand to the eco-friendly materials such as phytoncide which is extracted to plants in the textile industry, recently. It is interesting that alginic acid sodium salt(Alg-Na) is used to eco-friendly binder for the functional capsule finishing. In this study, we made PEO/Alg-Na blend solutions of various ratio and observed the changing binding property of the blend solutions according to PEO contents through FT-IR, DSC, contact angle, peel strength, etc. The viscosity of Alg-Na/PEO blend solutions increased with increase of contents and the viscosity quickly increased with increase of PEO content in Alg-Na 5% content, specially. It is shown that the hydrogen bond peak by blend of Alg-Na and PEO found through FT-IR analysis but the peak decreased in PEO above 60% content. And the peel strength was predominant in PEO 50% ratio.

• 한국수소및신에너지학회논문집
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• 제27권3호
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• pp.306-310
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• 2016

In Na-base Battery for ESS, ${\alpha}-Al_2O_3$ and metal bonding was used to prevent direct reaction between electrolyte and electrode. The hard metal was metalized at $1600^{\circ}C$ in a flowing hydrogen gas for high bonding strength. In this study, instead of hard metal metalizing, Ni was plated on ${\alpha}-Al_2O_3$ by electroless Ni plating technique and then bonded with metal. To enhance the bonding strength, surface of ${\alpha}-Al_2O_3$ was treated with $H_3PO_4$. The effects of strength and leakage of joining as a function of acid treatment time on ${\alpha}-Al_2O_3$ are described.

• 한국염색가공학회지
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• 제31권1호
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• pp.42-47
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• 2019

In this study, the effects of surface treatment of bamboo fiber on the physical properties of polypropylene(PP)/glass fiber(GF)/Bamboo fiber(BF) composite for engine cover were investigated. PP, GF and BF were fixed at 40%, 40% and 20% and the surface of bamboo fibers were treated to 0.5, 1.0 and 2.0% as an acid and alkali solution. PP/GF/BR composites using surface treated bamboo fibers were prepared and their tensile strength, bursting strength and impact strength were measured by universal testing machine(UTM). The composites with alkali treated bamboo fiber showed better mechanical properties than the acid treated composites. It was checked that the optimum alkali content was at 1.0% from the results of mechanical properties. The effect of surface treatment on the mechanical properties was confirmed by SEM images of fractured surface.

• 대한기계학회논문집A
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• 제28권12호
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• pp.1864-1870
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• 2004

A spot welded structures have an influence on a diverse climatic situation, for instance temperature, humidity and precipitation. In addition factors of environmental pollution such as acid rain, that courses corrosion, have the tendency to increase. But spot welded structures strength is affected by humidity and environment temperature. Therefore, it is important to evaluate effect of temperature and water immersion on strength properties of spot welded part. In this study, the strength distribution of spot welded plates is evaluated the environmental temperature of zinc coated steel plates. Test is conducted with welded part immersed in distilled and synthetic sea water. Specimens are immersed into water for 10, 100, 500 and 1000 hours to evaluate the offsets of water immersion time on tensile-shear strength under the conditions of -40, 0, 20 and 5$0^{\circ}C$. From this result, spot welded specimens with 5 mm clearance have lower tensile-shear strength in the distilled water or synthetic sea water than without clearance. And they have lower tensile-shear strength under -4$0^{\circ}C$ and over 5$0^{\circ}C$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.358-363
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• 2003

Spot welded structure is operated in diverse situation because of temperature, humidity and precipitation. In addition factors of environmental pollution such as acid rain, that courses corrosion, have the tendency to increase, But spot welded structure strength is affected by dampness and environment temperatures. Therefore, it is important to evaluate effect of temperature of spot welded part, In this study, the strength distribution of spot welded plates is evaluated about the environmental temperature of zine coated steel plates and test is conducted with welded part immersed in distilled and synthetic sea water. Specimens are immersed into water for 10, 100, 500 and 1000hours to evaluate the effects of water immersion time on tensile-shear strength under the conditions of -40, 0, 20 and $50^{\circ}C$. Strength is evaluated by tensile-shear test. The conditions of spot welding are 240kgf electrode force, 10KA welding current with 0 and 5mm clearance. From this study, spot welded specimens with clearance have lower tensile-shear strength in the distilled water or synthetic sea water comparing with spot welded specimens without clearance. And they have lower tensile-shear strength under $-40^{\circ}C$ and over $50^{\circ}C$.

• 접착 및 계면
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• 제17권4호
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• pp.136-140
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• 2016

본 연구에서는 aliphatic diamine 또는 aromatic diamine을 함유하는 다이머산계 폴리아미드 수지를 축합중합법으로 합성하였으며, FT-IR로 폴리아미드가 합성되었음을 확인하였다. Diamine의 구조에 따라 합성된 폴리아미드의 기계적, 열적 특성을 확인하였다. 방향족 diamine 함유 폴리아미드(DAP)의 경우 지방족 diamine 함유 폴리아미드(DAH) 보다 인장강도와 전단접착강도가 우수하였다. DSC thermogram에서 DAP는 DAH 보다 높은 $T_g$와 $T_m$을 나타내었다. DAP의 연화점은 $112-115^{\circ}C$이고, DAH는 $98-121^{\circ}C$이었다.

• 한국안전학회지
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• 제27권4호
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• pp.68-75
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• 2012

The biogenic corrosion of mortars adopted in sewage repair by sulfuric acid-producing bacteria was considered in this paper. Calcium aluminate cement (CAC) was known to resist microbiologically-induced corrosion significantly better than portland and blended portland cement.In this study, CAC as well portland cement mortars were tested as main binder to evaluate the corrosion resistance by the chemical immersion test. Replacement ratios of CAC were changed as 0, 20, 40, 50, 60% of OPC binder and 0, 2, 4, 6% of EVA(Ethylene Vinyl Acetate) were also adopted to increase properties of CAC repair mortars in sewage application. Setting time, compressive strength, acid resistance and adhesive strength were measured for various experiments. As a results of the experiments, the proper formulation of repair mortars was found at 40% of CAC and 4% of EVA. Finally, the CAC mortars adopted in field sewer pipe and were demonstrated to superior in adhesion and workability.

• 패션비즈니스
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• 제12권6호
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• pp.23-33
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• 2008

The physico-chemical characteristics by bleaching treatments were assessed by several instrumental analyses such as surface morphology, chemical structural change, color change as well as tensile strength. The change of morphological characteristic was observed through scanning electron microscope(SEM). The observation of the fine structure on hair surface by SEM showed the bleached hair had much damaged to hair cuticle, and some of cuticle surface were worn away. To investigate the chemical structural changes in hair keratin, the cross-sections of hair samples were directly analysed using Fourier transform infrared microspectroscopy(FT-IRM). The results showed the cysteic acid S=O band intensity was distinctively increased by performing the bleaching treatment. The cleavage of cystine was appeared to proceed primarily through the sulfur-sulfur (-S-S-) fission whereby cysteic acid was formed as a principal oxidation products. The distribution of amide I band in hair keratin was determined by attenuated total reflectance(ATR) FT-IR mapping image. The results showed that the outer side of hair cortex was more damaged than the inner side of the hair cortex. Also, during chemical bleaching of the hair with alkaline peroxide, the hair was turned to reddish yellow due to the oxidative degradation of eumelanin. This means the eumelanin is more unstable than pheomelanin in chemical oxidation. With bleaching, the tensile strength was also reduced as a results of the chemical oxidation.