• Journal of Adhesion and Interface
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• v.6 no.2
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• pp.6-12
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• 2005

The plasma generally, ionized gas state, is the 4th material state composed the universe. Generating the plasma artificially has been studied by spending energy and it has a lot of applications in human's life. There are several merits to modify the surface of polymer using plasma. Above all, plasma maintains the property of polymer because of it changes the property of surface only. Also, it doesn't use a organic solvent and it is the environment friendship because of there are no waste under processing. Furthemore, in case of high-pressure plasma, it is possible that automated-processing continuously. In this study, we tried the reforming of surface to rise the adhesive strength between the material of polymer, experimented the rising of adhesive strength through a experiment of peel strength by virtue of processing time and using gas, confirmed the change of polymer's surface through measuring the surface contact angle analyzer and scanning electron microscopy (SEM).

• Journal of Adhesion and Interface
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• v.7 no.4
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• pp.32-38
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• 2006

A series of organic-inorganic hybrids, PCL/EP/$SiO_2$, involving epoxy resin and triethoxysilane-terminated polycaprolactone elastomer (PCL-TESi) were prepared via polymerization of diglycidyl ether of bisphenol A (DGEBA) with amine curing agent KB-2 and sol-gel process of PCL-TESi. The curing reactions were started from the initially homogeneous mixture of DGEBA, KB-2 and the PCL-TESi. The organicinorganic hybrids containing up to 4.95% (wt) of $SiO_2$ were obtained and characterized by FT-IR, transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). It was experimentally shown that the swelling property in toluene, morphologies and thermal properties of the resulting hybrids were quite dependent on the contents of $SiO_2$. The crosslink network density decreases with increasing of the PCL-TESi. And in TEM, the phase separated morphology of these hybrids was found, which resulted from the coagulation of Si-O-Si networks resulting from $-Si(OC_2H_5)_3$ of PCL-TESi self-curing by hydrolytic silanol condensation, with the advancement of the curing reaction in the modified epoxy resin systems. Meanwhile, the change of the $SiO_2$ content made the morphologies changed from aggregated particles of Si-O-Si in the hybrid to nanocluster of interconnected Si-O-Si particles, then to aggregated Si-O-Si dispersing in the continuous cured epoxy phase again, and last to co-continuous interpenetrating network. The glass transition behavior of the hybrid material was cooperative motion of large chain segments, which were hindered by the inorganic Si-O-Si network. And in TG analysis, the characteristic temperature at 5% of weight loss was evidently increased from $120.5^{\circ}C$ of pure cured epoxy to $277.6^{\circ}C$ of 3.84% (wt) of $SiO_2$ modified epoxy due to the existence of Si-O-Si when PCL-TESi was added in the hybrid.

• Korean Journal of Materials Research
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• v.15 no.2
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• pp.115-120
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• 2005

The aim of this research is to develop the TRIP aided high strength low carbon steels using reverse transformation process. The $4\~8\%$ Mn steel sheets were reversely transformed by slow heating to intercritical temperature region and furnace cooling to room temperature. The stability of retained austenite depends on the enrichment of carbon and manganese by diffusion during the reverse transformation. The amount of retained austenite formed after reversely transformed at $625^{\circ}C$ for 6 hrs was about $50\;vol.\%$ in the $8\%Mn$ steel. The change in volume fraction of retained austenite with a holding temperature was consistent with the changes in elongation and the strength-ductility combination. The maximum strength-ductility combination of 40,000 $MPa{\cdot}\%$ was obtained when the $8\%Mn$ steel reversely transformed at $625^{\circ}C$ for 12 hrs. However, it's property was significantly decreased at higher holding temperature of $675^{\circ}C$ resulting from the decrease of ductility.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.91-95
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• 2002

Effects of freeze-drying time on the microbiological, sensory, and other characteristics of freeze-dried kimchi were investigated to optimize freeze-drying time for kimchi. Quality attributes of freeze-dried kimchi, including number of lactic acid bacteria (LAB), pH, sensory properties, brittleness, rehydration property, moisture content, and microstructure of Chinese cabbage were observed for 24, 48 and 72 h, respectively. Number of LAB and pH of the kimchi freeze-dried for 24 h were significantly changed in comparison with those of the kimchi not freeze-dried. However, further freeze-drying did not change markedly number of LAB and pH. Overall acceptability of the sample freeze-dried for 48 of 72 h was better than that of the sample freeze-dried for 24 h. As freeze-drying time increased, brittleness of the dried sample increased, and rehydration property was improved while dried weight and moisture content of the sample decreased. In conclusion, the sample freeze-dried for 48 h was better than the sample freeze-dried for 24 or 72 h, based on sensory properties and other characteristics.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.511-517
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• 2014

Recently, the fire by sheath heater has been occurred frequently on winter season. The sheath heater has simple internal structure and boils water simply. Therefore, the use of sheath heater has been increased. In this study, found the fire hazard property of sheath heater from understanding the fire mechanism through the experiment to get the measure for decreasing the occurrence of fire. For the analysis of the fire hazard property of the sheath heater, performed the test of temperature change and ignition temperature by using current product. On the result of test, the sheath heaters are the most dangerous appliance to arise fire. Water temperature controller attached to sheath heater is not sufficient to prevent overheating it. The sheath heater should have level switch of water and temperature controller for heater itself to shut off the power supply. Because the cause of fire by sheath heater is overheating itself in the situation of lack water.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.125-140
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• 2018

Tianjin, which is located on the west shore of the Bohai Sea, is part of China's Circum-Bohai-Sea Region, where very weak clay is deposited. From the 1970s to the early $21^{st}$ century, Tianjin marine clay deposits have been the subject of numerous geotechnical investigations. Because of these deposits' geological complexity, great depositional thickness, high water content, large void ratio, excessive settlement, and low shear strength, the geotechnical properties of Tianjin marine clay need to be summarized and evaluated based on various in situ and laboratory tests so that Tianjin can safely and economically sustain more infrastructure in the coming decades. In this study, the properties of Tianjin marine clay, especially its consolidation properties, are summarized, evaluated and discussed. The focus is on establishing correlations between the geotechnical property indexes and mechanical parameters of Tianjin marine clay. These correlations include the correlations between the water content and the void ratio, the depth and the undrained shear strength, the liquid limit and the compression index, the tip resistance and the constrained modulus, the plasticity index and the ratio of undrained shear strength and the preconsolidation pressure. In addition, the primary consolidation properties of Tianjin marine clay, such as the intrinsic compression line (ICL), sedimentation compression line (SCL), compression index, $C_c$, coefficient of consolidation, $C_v$, and hydraulic conductivity change index, $C_{kv}$, are evaluated and discussed. A secondary consolidation property, i.e., the secondary compression index, $C_a$, is also investigated, and the results show that the ratio of $C_a/C_c$ for Tianjin marine clay can be used to calculate $C_a$ in secondary consolidation settlement predictions.

• Journal of Korea Foundry Society
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• v.33 no.3
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• pp.103-112
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• 2013

Effect of Fe and Mn contents on the tensile properties of Al-4 wt%Mg-0.9 wt%Si alloy system has been studied. Common phases of Al-4 wt%Mg-0.9 wt%Si alloy system were ${\alpha}$-Al, $Mg_2Si$, ${\alpha}-Al_{12}(Fe,Mn)_3Si$ and ${\beta}-Al_5FeSi$. As Fe content of Al-4 wt%Mg-0.9 wt%Si alloy system increased from 0.15 wt% to above 0.3 wt%, ${\beta}-Al_5FeSi$ compound appeared. When Mn content of the alloy increased from 0.3 wt% to 0.5 wt%, morphology of plate shaped ${\beta}-Al_5FeSi$ compound changed to chinese script ${\alpha}-Al_{12}(Fe,Mn)_3Si$. As Fe content of Al-4 wt%Mg-0.9 wt%Si-0.3 wt%Mn alloy increased from 0.15 wt% to 0.4 wt%, tensile strength of the as-cast alloy decreased from 191 MPa to 183 MPa and, elongation of the alloy also decreased from 8.0% to 6.2%. Decrease of these properties can be explained as the formation of plate shape, ${\beta}-Al_5FeSi$ phase with low Mn/Fe ratio of the alloy. However, when Mn content of Al-4 wt%Mg-0.9 wt%Si-0.3 wt%Fe alloy increased from 0.3 wt% to 0.5 wt%, tensile strength of as-cast alloy increased from 181 MPa to 194 MPa and, elongation of the alloy increased from 6.8% to 7.0%. These improvements attribute to the morphology change from ${\beta}-Al_5FeSi$ phase to chinese script, ${\alpha}-Al_{15}(Fe,Mn)_3Si_2$ phase shape-modified from with high Mn/Fe ratio of the alloy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.3
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• pp.280-286
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• 2006

As a way to expand electric capacity in conductor with electric power demand, STACIR/AW (Super Thermal-resistant Aluminum-alloy Conductors Aluminum-clad Invar-Reinforced) conductor which has high electric current and heat resistance characteristics have been developed. STACIR/AW power line is mechanical composite wire composed of steel cores for dip control and aluminum conductors for sending electric current. Recently, to ensure stable operation and prediction of wire life span of STACIR/AW conductor, a heat property of STACIR/AW conductor have been investigated. In the present work, a change of essential property with long term-heat exposure of STACIR/AW conductor and its structure material, INVAR wire and Al conductor, have been investigated. INVAR/AW is approximately $3.2\;{\mu}m/m^{\circ}C$. thermal expansion coefficient of INVAR/AW wire increases with time of heat exposure. the thermal expansion coefficient of INVAR/AW is markedly influenced by heat and mechanical treatment. creep rate(0.242) of STACIR/AW $410\;mm^2$ conductor at room temperature is much higher than that(0.022) at $210\;^{\circ}C$ STACIR/AW $410\;mm^2$ conductor has minimum creep rate at operating temperature. To lower creep rate with increase temperature is more unique characteristics in STACIR/AW. It is expected that STACIR/AW turned its tension to INVAR/AW at the transition temperature. at room temperature, the tension apportionment of INVAR/AW in STACIR/AW is about $50\;\%$. but whole tension of STACIR/AW is placed on the INVAR/AW alone of core metal above transition temperature.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.168-175
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• 1990

Softners-BHICS, BBICS, and BTICS were prepared from 1, 2-disubstituted imidazoline compounds, such as 1-behenoylaminoethyl-1-glycidyl-2-heneicosylimidazolinium chloride(BHIC), 1-behenoylbis(aminoethyl)-1-glycidyl-2-heneicosylimidazolinium chloride (BBIC), and 1-behenoyltris(aminoethyl)-1-glycidyl-2-heneicosylimidazolinium chloride(BTIC), and treated to acrylic fiber. The measurements of softness, lubricating and antistatic properties showed that they have not only good softness and lubricating property but also a little antistatic property. Furthermore, the initial bending resistance for BBICS and BTICS was 5 grade, and remained 3~4 grade after 5 times washing. As results of these tests, they showed good softner effects having durability. The prepared softners were proved to be durable softner through a series of experimental results for washable properties of feeling by varying treating temperature and pH change.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.505-510
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• 2009

It is well known that the properties of concrete such as the compressive strength, water permeability, water tightness and durability are affected by micro-structure in hardened cement paste. Especially, for durability of concrete, watertightness of cementitious materials is the most critical property among various properties. Recently, many types of material such as organic and/or inorganic materials are used for watertightness of concrete. In this study, we examined the effect of fluorine-based emulsion on watertightness property. And we also discussed the change of microstructure and formation of hydrates in hardened cement paste by the addition of fluorine-based emulsion. Cement paste with fluorine-based emulsion showed improvement of watertightness by the surface activation of cement paste and by formation of $CaF_2$ fine crystals in cement pore structure.