• Textile Coloration and Finishing
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• v.33 no.4
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• pp.191-201
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• 2021

In this study, an eco-friendly indigo reduction system(scale up reduction, use of buffer solution, and pH control) using baker's yeast(Saccharomyces cerevisiae) was applied for natural indigo(Polygonum tinctorium) dyeing of Hanji fabric and Hanji-mixture fabric(Hanji/Cotton, Hanji/Silk). The effect of concentration of baker's yeast, repeat dyeing, and bath reuse was investigated in terms of dye uptake indicating reduction power. And the oxidation-reduction potential(ORP) was monitored. We also evaluated color properties and colorfastness according to the color strength. The yeast concentration did not significantly affect the maximum reduction power. However, the highest yeast concentration was effective in improving the initial dye uptake, and its the reduction retention power was the most excellent. Even on the last reduction day, the effect of increasing the dye uptake by repeat dyeing was observed. And it was confirmed that the reduction bath could be reused for up to 30 days by supplementing yeast at the end of reduction. For all the fabrics used, deeper and darker PB color were obtained by repeat dyeing. As dyeing was repeated, purplish tint got stronger on the Hanji/Silk fabric compared to other fabrics. Regardless of the composition of Hanji fabrics and color strength, washing and dry cleaning fastness were relatively good with above rating 4-5, and fastness to rubbing and light were acceptable with a rating 3-4 ~ 4-5. The eco-friendly natural indigo dyeing process using niram and baker's yeast would offer global marketability and diversity of Hanji product as a sustainable high value-added material.

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.449-451
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• 1992

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.305-309
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• 2006

In this paper vibration reduction characteristics of floating floors used in railway vehicles are studied. Vibration reduction characteristics are compared through a series of tests for elastically-coupled floor and rigidly-coupled floor. It was found that elastically-coupled floor has larger vibration reduction amount than rigidly-coupled floor. Around the fundamental natural frequency, however, elastic floor has poor vibration reduction effect than rigid floor. Measures to reduce structure-borne noise are also discussed based on the test results. Structure-borne noise for running railway vehicles cannot be reduced by an effort to deviate resonance between natural frequency of floors and major exciting forces. Instead, reducing vibration level of top floor and using covers which have low sound radiation coefficient will be effective for reducing structure-borne noise.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.3
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• pp.149-157
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• 2017

Since sloshing effects influences ship motions including floater's natural frequencies. The significant factors changing ship motions are inner liquid impact loads and inertia forces and moments with respect to its filling ratio. This means that changing sloshing loads with sloshing effects reduction device (SERD) may control ship motions. In this regard, conceptual model for adjustable SERD was suggested by authors and then implanted into fully coupled program between vessel motion and sloshing. By changing clearances of baffles in the inner tank which were component of SERD, then the roll RAOs from each case were obtained. It is revealed that using well-controlled SERD can maintain natural frequencies of floater even inner tank has different filling ratio.

• Fashion & Textile Research Journal
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• v.14 no.2
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• pp.304-310
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• 2012

The natural dyeing of silk fabric with Scutellaria baicalensis extract was investigated. The proper colorant concentration, dyeing temperature, dyeing time, and pH for the dyeing of silk fabric with Scutellaria baicalensis extract were 90% v/v, $90^{\circ}C$, 60 minutes and pH 3, respectively. In various mordanted methods, the K/S values of mordanted methods were higher than those of unmordanted methods. Light colorfastness and washing colorfastness of Fe mordanted silk fabric was improved by mordanting. The antibacterial properties of dyed and mordanted silk fabric showed a high reduction rate, and Scutellaria baicalensis extract was showed effective bacterial reduction.

• The Research Journal of the Costume Culture
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• v.21 no.5
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• pp.699-707
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• 2013

The natural dyeing of silk fabric with Thuja orientalis extract was investigated. The proper colorant concentration, dyeing temperature, dyeing time, and pH for the dyeing of silk fabric with Thuja orientalis extract were 100% v/v, $80^{\circ}C$, 80 minutes and pH 3, respectively. In various mordanted methods, the K/S values of mordanted methods were higher than those of unmordanted methods with increasing mordant concentration. Light colorfastness and washing colorfastness of Cu or Fe mordanted silk fabric was improved by mordanting. The antibacterial properties of dyed and mordanted silk fabric showed a high reduction rate, and Thuja orientalis extract was showed effective bacterial reduction. The dyed and mordanted fabric with Thuja orientalis extract showed a superior ultraviolet protection property.

• Fashion & Textile Research Journal
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• v.13 no.3
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• pp.432-437
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• 2011

The natural dyeing of silk fabric with Rheum undulatum L. extract was investigated. The proper colorant concentration, dyeing temperature, dyeing time, and pH for the dyeing of silk fabric with Rheum undulatum L. extract were 90% v/v, $90^{\circ}C$, 80 minutes and pH 3, respectively. In various mordanted methods, the K/S values of mordanted methods were higher than those of unmordanted methods. Light colorfastness of mordanted silk fabric was improved by mordanting. The antibacterial properties of dyed and mordanted silk fabric showed a high reduction rate, and Cu mordant was showed the most effective bacterial reduction.

• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.1012-1013
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• 1994

• Fashion & Textile Research Journal
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• v.10 no.5
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• pp.771-778
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• 2008

The natural dyeing of cotton fabric with Perilla frutescens var. acuta extract was investigated. The proper extraction temperature and time were $100^{\circ}C$ and 120 minutes. The proper temperature, time and colorant powder concentration for the dyeing of cotton fabric with Perilla frutescens var. acuta powder were $90^{\circ}C$, 60 minutes and 15%(o.w.b.), respectively. In various mordanted methods, the K/S values of simultaneous-mordanted methods were higher than those of pre-and post-mordanted methods. And the Cu-and Fe mordant showed higher K/S values than those of other mordants. Light colorfasness of mordanted cotton fabric was poor, but the other colorfasnesses were shown to be good. The cotton fabric mordanted with Cu mordant was showed effective bacterial reduction.

• Earthquakes and Structures
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• v.9 no.6
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• pp.1181-1192
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• 2015

In this paper, an analytical method is proposed to study the effect of crack and axial load on vibration behavior and stability of the cracked columns. Using the local flexibility model, the crack has been simulated by a torsional spring with connecting two segments of column in crack location. By solving governing eigenvalue equation, the effects of crack parameters and axial load on the natural frequencies and buckling load as well as buckling load are investigated. The results show that the presents of crack cause to reduction in natural frequencies and buckling load whereas this reduction is affected by the location and depth of the crack. Furthermore, the tensile and compressive axial load increase and decrease the natural frequencies, respectively. In addition, as the compression load approaches to certain value, the fundamental natural frequency reaches zero and instability occurs. The accuracy of the model is validated through the experimental data reported in the literature.