• Elastomers and Composites
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• v.48 no.3
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• pp.225-231
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• 2013

In this study, we observed the effect of carboxylated SBR latex and zinc oxide on styrene-butadiene-styrene( SBS) composites for improving abrasion and debris. SBS composite, which added only silica, showed poor mechanical properties, NBS abrasion, and debris, caused by strong filler-filler interaction of silica. In case of adding carboxylated SBR latex, mechanical properties, NBS abrasion and debris of SBS composite were improved. Because of carboxyl group of carboxylated SBR latex interacted with silanol group of silica. Both carboxylated SBR latex and zinc oxide were added, SBS composite showed highest mechanical properties, NBS abrasion, and debris by forming ion cluster between carboxylated SBR latex and zinc oxide. By FT-IR analysis, ion clusters were confirmed that observed zinc carboxylated group stretch peak at $1550{\sim}1650cm^{-1}$ range. SBS composite, SC-4, showed excellent mechanical properties ; tensile strength $156kgf/cm^2$, elongation 936%, tear strength 59.4kgf/cm ; and excellent abrasion characteristics ; NBS abrasion 338%. Also, debris of SC-4 was minimized and showed wave-shape in fracture surface.

• Elastomers and Composites
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• v.38 no.3
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• pp.227-234
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• 2003

Silicone composites for high voltage insulator (HVI SC) were prepared by adding aluminum trihydrate(ATH) treated by surface treatment agent to base silicone compound at the ratio oi 100:20, 100:40, 100:60, 100:80, and 100:100, respectively And also, ATH was treated by various surface treatment agents, such as stearic arid, acryl silane, and vinyl silane under compounding process. Mechanical properties and electrical properties were investigated for the various contents of ATH and surface-treatment agents. Mechanical properties such as tensile strength, elongation, and tear strength decreased as the load of ATH increased. Volume resistivity, AC break down strength, and tracking resistance for HVI SC containing ATH treated by vinyl silane were better than those for HVI SC containing ATH treated by other surface treatment agents, such as stearic acid and acryl silane. Polymer-filler interaction of silicone composites according to surface treatment agents was studied by measuring bound rubber contend(BR). From the experimental results, BR of silicone composite containing ATH treated with vinyl silane was higher than that of the others. The degree of rule for silicone composite was investigated using Rheometer. Maximum torque of silicone composites contaning ATH treated with vinyl silane was higher than that of silicone composite contaning ATH treated with other surface agents.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.37-46
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• 2010

This study was carried out to develop new application field and obtain the basic data of mixed paper with wood pulp and chitosan fiber for producing functional paper. Two types of wood pulp, such as SwBKP and HwBKP, were mixed with chitosan fiber. Physical and optical properties, water vapor absorption, air permeability, antibacterial activity and ash were measured. And the surface morphology of manufactured paper was observed using SEM. The results are as follows. It was revealed that density, breaking length, burst index, tear index, folding endurance and brightness were reduced but water vapor absorption and air permeability were on the rise in the structural view of SwBKP according to increasing the chitosan fiber ratio. Those HwBKP added chitosan fiber were great not only in the strength but also water vapor absorption and air permeability except for brightness. The water vapor absorption was lower and the air permeability was higher in the HwBKP added various chitosan fiber ratios than those with no chitosan fiber. It is estimated that these properties were related with various mixed rate of chitosan fiber. Particularly, air permeability was strongly dependent on the mixed rate of chitosan fiber. The chitosan fiber has superior antibacterial property, comparing with wood fiber. Adding chitosan fiber to the wood pulp was found to have an excellent antibacterial activity, more than 90%. The ashes were determined within 0.5%. Special bonds between chitosan fiber and wood pulp was observed by SEM and it means that the chitosan fiber were combined equally in the interior of wood pulp. In conclusion, mixing wood pulp with chitosan fiber can not only improves the quality of paper but also extend the usage of paper as a functional paper by using inherent property of chitosan. After all, production of functional paper added chitosan fiber is expected for new valuable industry of paper.

• Elastomers and Composites
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• v.41 no.1
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• pp.27-39
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• 2006

In this study, modified DA-MMT filled NR/DA-MMT nanocomposites were manufactured by a latex method and a compounding method. Cure characteristics and mechanical properties of the Cloisite 15A, carbon black, Na-MMT filled NR compounds and the DA-MMT filled NR compound by a latex method were also evaluated. The filler content of all compounds was 10phr except the carbon black filled compound. Degree of intercalation and dispersion was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). According to the XRD diffraction pattern and TEM analysis, extensive intercalation and homogeneous dispersion of the clay were obtained after the two-roll milling. Although the layer distance was increased, some parts of DA-MMT showed the layer distance of Na-MMT after vulcanization. DA-MMT filled NR compounds showed the highest ODR torques, tensile strength, modulus, and tear energy. The NR/DA-MMT nanocomposite (by a latex method) compared with a NR/DA-MMT nanocomposite (by a compounding method) was found that the improvement of the mechanical properties was mainly due to the degree of dispersion of the clay.

• Rubber Technology
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• v.9 no.1
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• pp.1-12
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• 2008

Effects of silane modifier, bis(triethoxysilylpropyl) tetrasulfide (TESPT(S4)) and bis(triethoxysilylpropyl) disulfide (TESPD(S2)), on silica filled compound were investigated upon processability, dynamic, mechanical, heat build-up, blowout properties, and silica dispersion in natural rubber (NR). The temperature of the S2 treated silica compound generated higher than that of the S4 treated compound during internal mixer compounding. The shear viscosity of the S2 compound exhibited lower than that of the S4 compound and the viscosity measured in dynamic mode was close to each other. The elongation modulus of the S2 compound exhibited lower than that of the S4; however, the tear resistance strength of the S2 compound exhibited higher than that of the S4 compound. The loss tan$\delta$ values of the S2 compound exhibited higher than those of the S4 at room temperature. The augmentation of the test temperature lowered the tan$\delta$ values of each compound, which results in close tan$\delta$ values to each other at $100^{\circ}C$. The S2 compound deformed less than the S4 compound, and the blowout time of each compound was close to each other. The S2 compound generated more heat build-up than the S4 compound. The abrasion loss of the S2 compound was less than that of the S4 compound. The size of the silica agglomerate reduced on both S4 and S2 compounds upon vulcanization. The addition of the bifunctional silanes (S2 and S4) on silica filled NR compound improved the processability of each compound and their effects were more significant on the S2 compound than the S4 compound. After vulcanization the silica agglomerate size of each compound reduced compared with before vulcanization.

• Journal of the Korean Wood Science and Technology
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• v.10 no.3
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• pp.168-179
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• 1982

The first step to utilize the growing resources of Italian poplar (Populus euramericana I-476) for pulp-Woods, its characteristics and adaptabilities to the pulp industry must be investigated completely. The plantation methods are important for its fast growing in stock, and no less important is the cutting age for its utilization as pulpwood. In this paper, the stone groundwood pulping, refiner groundwood pulping and chemi-groundwood pulping characteristics by the age of tree, along with their physical and chemical characterstics were tested, and relationships between the age groups were analyzed to find out the optimum felling age. The results obtained are as follows: 1. The coefficient of pliability was a little higher in the case of younger trees. 2. The water retention value of each pulp was directly proportional to its physical strength, but this tendency was not detected between the age groups of sample woods. 3. Generally, the physical strength of younger wood pulp was lower regardless of the pulping process. But in the case of pretreatment with NaOH, Asphund and CGP pulp from 5 year old sample wood were stronger in physical strengths than those of GP and Asplund pulp with no pretreatment from 10 years old sample wood. 4. The tear factor of Asplund pulp with alkali pretreatment was higher than that of CGP pulp but the breaking length and the burst factor was similar in all processes. Considering the pulp yield and its brightness, CGP process seems to be advantageous. 5. The dissimilarity of physical strength between 7 and 10 years old wood pulp was not very large in all pulping processes but the physical strength of 5 year old wood pulp was very weak. In the of groundwood pulping from Italian poplar woods, 5 year old wood pulp should be mixed with other long fiber pulp for making a good paper.

• Journal of Ocean Engineering and Technology
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• v.28 no.1
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• pp.28-33
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• 2014

The Korean icebreaking research vessel "Araon" performed four sea trials in the Arctic and Antarctic Seas. The ice properties, such as the ice thickness, floe size, ice strength, and power of the vessel were quite different in these trials. To compare the speeds of ship with the same ice strength and power, the AARC (Arker Arctic Research Center) method is used with a vessel power of 10 MW and an ice strength of 630 Pa in this paper. Based on the analysis results, the speed of the ship was 1.62 knots (0.83 m/s) with a 1.02-m ice thickness and 2.5-km floe size, 5.3 knots (2.73 m/s) with a 1.2-m ice thickness and 1.0-km floe size, and 13.8 knots (7.10 m/s) with a 1.1-m ice thickness and 200-m floe size. The analysis results showed that the ship speed and floe size have an inversely proportional relationship. Two reasonable reasons are given in this paper for the final result. One is an ice breaking phenomenon, and the other is the effect of the ice floe mass. For the breaking phenomenon, the ice breaking force is very small because the ice floe is not breaking but tearing when a ship is passing through a small ice floe. Regarding the effect of the ice floe mass, it is impossible for a ship to push and tear an ice floe if the mass of the ice floe is too large compared to the mass of the ship. The velocity of the ship decreases when the ice floe has a large mass and a large size because the ship has to break the ice floe to move forward.

• Health Policy and Management
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• v.9 no.1
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• pp.72-109
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• 1999

This study is conducted to investigate the current status on the utilization of health care and plan for solving this problem. The claims data of the fiscal tear 1995 obtained from the regional health insurance society are used for the study. The main findings of the study are summarized as follows. Indexes(The Extremal Quotient(EQ), coefficients of variance(CV's))which represent the regional difference in the admission rate of the tertiary medical diagnosis group report that there is difference in quantity and quality of utilization of health care. The admission rate is lower in the big city areas, Kyoungkido, Kangwondo and Chunlapukdo. Even after age-sex adjustment, the admission rate is still low in Kangwondo, Chunlapukdo and Kyoungsangpukdo. The big city areas tend to have higher rates in the expenses per claim, hospital days per claim, and daily expenses but the rates are still low in some area in Kangwondo, Chunlanamdo and Kyoungsangpukdo. This result remains as same after age-sex adjustment. There is a large regional difference in average utilization rate for the tertiary hospital of the tertiary medical diagnosis group: 57.2%(SD 11.53). The utilization rates for the tertiary hospital in their large catchment area are 96.34%, 83.19% and 73.22% in each Kyoungin, Kyoungnam and Kyoungpuk areas whereas it is lower in a Chungpuk and Chungnam areas. The regional differences of health care utilization of the tertiary medical diagnosis group gave some relationships with their geographical characteristics such as socio-economic characteristics and supply factors of medical services. It is important that many medical policies should be developed in order to minimize and balance out the regional differences of health care utilization. The service allocation policy should include the reconstruction of manpower policy, developing the resource allocating formula, finding the self-sufficient catchment area and reforcing of public health services. Moreover, in order to achieve the balanced development by region, they should investigate and consider each county's microscopic properties under the consistent macrocopic policy. The further studies to find causes of regional difference are needed.

• Fashion & Textile Research Journal
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• v.15 no.2
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• pp.294-301
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• 2013

Sustainable fashion & textile is more than eco fashion & textile with the concepts for the next generation's happiness, prosumer value, and community responsibility. This study considers methods to enhance fashion and textile industry sustainability in accordance to clothing types (material, product life and washing properties) and to investigate company strategies. Company strategies are of redesign with stock, volunteering & measuring trash amount, participation by evaluation stores, clerk environment education, hiring QC specialist and reinforcing partnerships. For the case of daily innerwear, throwing away and recycling is more efficient for the environment than laundering in the consumer use stage; subsequently, we recommend the use of polypropylene fiber (a cheap and an eco-friendly material) for this item that can be recycled and reformed after use. For the case of single layer clothing (such as sportswear, blouse or pants) we recommend the use of thermoplastic materials with welding or fuse assembling technology instead of a sewing method of seams as well as the recycle design that is simply melted and reformed into new clothing without an after use dissembling process. Secondhand use or resale is suitable for denim/jean items if the clothing has a storytelling or private history tag. Lastly, module-type jacket or coat shows the variety of styles with one clothing worn w/o collar or sleeve details and changed into vest/coat; in addition, it is possible to add or partly tear off some jacket/coat fibers of the felt material to reform it into a new design.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.299-303
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• 1999

In this paper, to investigate the deinkability of domestic and Australian old newsprint according to aging time, two types of newsprint printed with commercial offset ink in domestic(K; Korean newsprint, C; Canadian newsprint), Japanase(J) and Australian(A) old newsprint were aged naturally for 10, 30, 90, 180 days, and then yield, brightness, fiber length, and physical properties (tensile index, tear index, burst index) were evaluated according to aging time. As the aging time increased, the yield and brightness of respective samples decreased. The brightness and yield were decreased in the order of A, K, J and C. The brightness and strength of newsprint varied according to the ink formulation and kinds of pulp and wood. The decreasing order of strength is subsequently J, K, C and A.