• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.38-45
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• 2009

In this study, interfacial properties were measured for imidazoline type cationic surfactant system which has been widely used as a fabric softener, a dispersant, an anti-static agent, a bleach activator, and an emulsifier. The CMC of imidazoline surfactant was near $6{\times}10^{-5}mol/L$ and the surface tension at CMC was about 32 mN/m. It was found that surface tension was not affected by surfactant concentration but decreased with an increase in pH. The interfacial tension between 1 wt% aqueous solution and n-dodecane was shown to be about 0.01 mN/m and equilibration time was not affected by pH. Phase behavior experiment in a binary aqueous surfactant system showed that only micellar solution of $L_1$ phase was found under conditions of temperature and pH investigated during this study. Only a two-phase region consisting of lower-phase microemulsion in equilibrium with excess oil phase existed under the same conditions, when oil was added to the binary surfactant system. The foam stability measured with 1 wt% surfactant solution increased with pH, which is consistent with surface tension measurement result. QCM(quartz crystal microbalance) measurement showed that surfactant adsorption increased with surfactant concentration but decreased with pH. According to the friction measurement, best fabric softening effect by imidazoline surfactant system was found under alkali conditions.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.345-356
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• 1994

Each of the three cationized compounds synthesized previously, poly(OMA-co-DAMA)[PODC], poly(DMA-co-DAMA)[PDDC] and poly(EMA-co-DAMA)[PEDC] was blended with waxes, emulsifiers and cationized fatty carbamide(ODTCC) synthesized in this study for the preparation of some durable softening water-repellenting agents, PODCW, PDDCW and PEDCW. The results of washability, tearing strength, crease recovery and contact angle of the cotton fabrics treated with PODCW, PDDCW and PEDCW with and without textile finishing resin, showed remarkable improvement of the physical properties. Rating of water repellency of cotton fabric treated with PODCW was 80, but those treated with PDDCW and PEDCW were not high enough to use in industry. Proper curing temperature of the synthesized water-repelleting agents was $140^{\circ}C$; proper using concentration was 3wt%; sodium acetate was the best catalyst for water-repellenting agents among the used, and proper concentration was 0.6wt%. From the results of reaction mechanism of cellulosic fiber with water-repellenting agent and washability of the fibers treated with water-repellenting agents the prepared water-repellenting agent proved to be durable. Surface structures of cotton fabrics treated with water-repellenting agent were investigated by SEM.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.149-154
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• 2003

Changes in mineral (Ca, Mg) contents and pectic substances of mature-green 'Nanko' Mume fruits hermetically packaged in 0.03 mm low density polyethylene (LDPE) films with and without gas absorbents were examined during storage at $25^{\circ}C$ for 10 days. Each packaging contained 10 g $Ca(OH)_2$ as a carbon dioxide scavenger, 30 g $KMnO_4$ as an ethylene scrubber or their mixture. In the presence of the ethylene scrubber, losses in mineral contents of alcohol insoluble solids and water soluble pectin were remarkably suppressed, whereas no significant difference was observed in the Ca content between the fresh fruit and those stored for 10 days. Fruits packaged with the ethylene absorbent retained higher amount of pectic substances than those with other packaging treatments. Degradation of the pectic substances into small molecules was also noticeably reduced when the ethylene scrubber was used. Overall results showed that the combination of the gas permeable film and the ethylene absorbent could be applied to mature-green Mume fruits as an effective packaging method to retard the texture softening during storage at the ambient temperature.

• Elastomers and Composites
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• v.44 no.3
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• pp.282-289
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• 2009

The pressure-sensitive adhesive(PSA) tapes are widely used as floor-sealing material in Korean constructive industry. However, the general PSA tapes can not seal the apertures completely. This is one of main reasons to cause imperfect finishing. In order to solve the problems, the asphalts were modified by FKM powder and SBS in this study. The physical properties of modified asphalts were examined by measuring the softening point, viscosity, tensile strength and adhesion strength of FKM and SBS modified asphalt. The softening point of SBS modified asphalt was increased greatly due to the formation of network structure in asphalt. Also, the change of adhesion strength of SBS modified asphalt with temperature was not so great comparing to those of pure asphalt and FKM modified asphalt. The best results of pressure-sensitive adhesion could be obtained by the SBS(linear) modified asphalt containing 6 wt.% of linear type SBS.

• Korean Journal of Food Science and Technology
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• v.51 no.3
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• pp.243-247
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• 2019

Calendula (Calendula officinalis L.) petals are edible flowers which have been used as a decorative ingredient in dishes or as a medicinal food. In this study, the anti-skin aging potential of calendula petals was investigated. Additionally, the texture was softened by non-enzymatic methods to broaden their application as a food or cosmetic agent. Treatment of calendula prevented ultraviolet-induced matrix metalloproteinase-1 expression in skin cells. We investigated whether heating-based processing could soften calendula petals. The results from the punctual test demonstrated significant changes in the hardness of calendula petals depending on the pH, heating temperature, and time. Although there were minor differences among various processing conditions, the largest alteration in hardness was observed when the petals were softened by incubation at $80^{\circ}C$ and pH 2.3 for 120 min. Collectively, these results show that the application of proper processing conditions can soften calendula petals without using enzymes.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.203-210
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• 2013

This study was conducted to investigate the optimum storage temperature and the effect of 1-methylcyclopropene (1-MCP) on the postharvest physiology and quality of plumcot (Prunus salicina Lindle. ${\times}$ Prunus armeniaca L.) 'Harmony' fruits. plumcot fruits were stored at 0, 5, 10, and $20^{\circ}C$, respectively, with three different ripeness stages grouped by skin color development. Furthermore, we treated $1{\mu}L{\cdot}L^{-1}$ 1-MCP was treated at $10^{\circ}C$ for 17 hours and stored at $10^{\circ}C$ for 12 days to evaluate the effectiveness for better shelf-life. The results indicated that lower storage temperature than room temperature effectively reduced the respiration rate with delaying quality changes. While, the fruits showed worse fruit taste than the fruits stored at 10 and $20^{\circ}C$. Reversely, the fruits stored at $20^{\circ}C$ showed more respiration rate and ethylene production. 1-MCP treatment effectively reduced the skin red color development, ethylene production, $CO_2$ and softening of plumcot 'Harmony' fruits. Overall data indicated that the optimum harvest time and storage temperature could be 30-50% red color and near $10^{\circ}C$. Postharvest 1-MCP application at the level of $1.0{\mu}L{\cdot}L^{-1}$ could maintain fruit quality well in plumcot fruits.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.515-521
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• 2000

The effect of precipitates on the high temperature tensile properties of cast alloy 718 was investigated by phase extraction method and microstructural observation. The value of tensile strength and elongation gradually decreased with increasing testing temperature up to $760^{\circ}C$. Elongation of the alloy increased, while tensile strength decreased above 76$0^{\circ}C$. The amount of precipitates in the specimen that tensile tested at $760^{\circ}C$ showed maximum owing to stress assisted precipitation. Therefore, the alloy exhibited the lowest value of the elongation and the degree of decrease in yield strength at this temperature due to high flow stress of precipitates. Little amount of precipitate, especially $\gamma$' and $\gamma$＂, resulted in softening of the alloy at the temperature above $760^{\circ}C$.

• Geophysics and Geophysical Exploration
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• v.23 no.1
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• pp.1-12
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• 2020

In the development of geodynamic structures such as subduction and rift zones, a weakening mechanism is essential for localized weak zone formation in the lithosphere. Shear heating, a weakening mechanism, generates short-wavelength temperature elevation in the lithosphere; the increased temperature can reduce lithospheric strength and promote its breakup. A two-dimensional elastoplastic extensional basin model was used to conduct benchmarking based on previous numerical simulation studies to quantitatively analyze shear heating. The amount of shear heating was investigated by controlling the yield strength, extensional velocity, and strain- and temperature-dependent weakening. In the absence of the weakening mechanism, the higher yield strength and extensional velocity led to more vigorous shear heating. The reference model with a 100-MPa yield strength and 2-cm/year extension showed a temperature increase of ~ 50 K when the bulk extension was 20 km (i.e., 0.025 strain). However, in the yield-strength weakening mechanism, depending on the plastic strain and temperature, more efficient weakening induced stronger shear heating, which indicates positive feedback between the weakening mechanism and the shear heating. The rate of shear heating rapidly increased at the initial stage of deformation, and the rate decreased by 80% as the lithosphere weakened. This suggests that shear heating with the weakening mechanism can significantly influence the strength of relatively undamaged lithosphere.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.191-200
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• 2003

This paper presents the rheological properties of bitumen for reducing negative skin friction. The bitumen has been widely used due to both the cost and construction effectiveness. Also, it is well known that the use of bitumen for reducing negative skin friction renders the best results among other available methods. Three different modified bitumens were used for the testing programs. The physical tests include the penetration, the softening point and penetration index. The rheological tests include phase angle, complex modulus, creep tests and flow tests. The tests were conducted at four different temperatures(15, 30, 45 and 6$0^{\circ}C$) in order to simulate the field condition. The test results were analyzed using the phase angle, G$^*$/sin $\delta$, creep compliance and shear viscosity. The result of tests showed that the phase angle increased and G$^*$/sin $\delta$ decreased with the increase of temperature. The creep compliance increased as the loading time increased. The difference of the creep compliance is detected as the time and temperature are varied, however, the difference of the shear viscosity is not significant among the samples tested in this study. The rheological properties of the bitumen also showed that the physical testing method and the temperature dependant testing method are somewhat limited to showing and expressing the full rheological properties of the modified bitumen. The introduction of the time and the temperature dependent testing method is necessary to find out the full rheological properties of the modified bitumen.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.537-542
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• 2016

In this study, we have prepared mesophase pitch from pyrolysis fuel oil (PFO) by heterogeneous reforming process. This process was conducted by direct fluorination at various temperature and followed by the heat treatment at $390^{\circ}C$. The reformed pitch was then investigated by softening point analysis, elemental analysis, fourier-transform infrared spectroscopy, high resolution X-ray diffraction and polarization microscope analysis. Carbon contents of reformed pitch increased according to increasing the reaction temperature of fluorination, while oxygen, nitrogen and sulfur contents were completely eliminated. As the fluorination temperature increased, the creation, growth, coalescence and alignment process of mesophase spheres were observed. Also the interlayer spacing of carbon hexagonal planar structure decreased, while its crystalline size increased. In addition, aromatic ring compound contents increased by the condensation polymerization of aliphatic compound. These results can be attributed to the radical reactivity of the fluorine increased as the reaction temperature increased. It was considered that the fluorination reaction could help PFO to generate aromatic compounds, via promoting polymerization by radical reaction.