• Macromolecular Research
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• v.12 no.1
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• pp.85-93
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• 2004

We have prepared poly(ethylene terephthalate) (PET) nanocomposites filled with two different types of fumed silicas, hydrophilic (FS) and hydrophobic (MFS) silicas of 7-nm diameter, by in situ polymerization. We then investigated the morphological changes, rheological properties, crystallization behavior, and mechanical properties of the PET nanocomposites. Transmission electron microscopy (TEM) images indicate that the dispersibility of the fumed silica was improved effectively by in situ polymerization; in particular, MFS had better dispersibility than FS on the non-polar PET polymer. The crystallization behavior of the nanocomposites revealed a peculiar tendency: all the fillers acted as retarding agents for the crystallization of the PET nanocomposites. The incorporation of fumed silicas increased the intrinsic viscosities (IV) of the PET matrix, and the strong particleparticle interactions of the filler led to an increased melt viscosity. Additionally, the mechanical properties, toughness, and modules of the nano-composites all increased, even at low filler content.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.10
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• pp.460-466
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• 2014

This paper uses in-situ thermal response tests to present the characteristics of the ground thermal conductivities of three different SCW GHX. These SCW GHXs were installed in the same site in Seojong City. The three different cases are distinguished by the flow direction and the presence of a filler. The first type (A) is constructed for water to flow downstream. The second (B) and third (C) types are designed for water to flow upstream, and a filler is additionally inserted into the third type. The results of the in-situ thermal response tests, indicate that the ground thermal conductivity for types (A), (B) and (C) are of $4.84W/m{\cdot}K$, $3.40W/m{\cdot}K$, and $11.62W/m{\cdot}K$, respectively.

• Journal of the Korean Ceramic Society
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• v.51 no.2
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• pp.132-137
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• 2014

The study was performed with low-grade limestone, which is used to make cement or is disposed of due to its low CaO content. In this study, the optimal condition of limestone with which to manufacture precipitated calcium carbonate (PCC) and limestone in fiber was determined through in-situ reactions. The best firing condition is with slaked lime with rapid cooling after 2 h of firing at $1000^{\circ}C$. In addition, the content of CaO can be increased by sorting the low-grade limestone using a 200 mesh filter, and the optical quality of old newspaper (ONP) was similar when using both low-grade and high-grade limestone. Also, controlling the particle size of PCC is an important factor pertaining to the optical characteristics of paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.76-80
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• 2015

In filler loaded paper, the size of the filler affects its strength, optical and surface properties. As the size of the filler increases, tensile strength and bulk usually increases, opacity decreases, and smoothness becomes worse. Pre-flocculation of GCC (grounded calcium carbonate) makes large diameter flocs at aqueous medium that consists of multiple GCC particles, but they collapse to 2-dimensional shape in dried paper and makes low bulk paper. The hybrid calcium carbonate (HCC) that was made by in-situ $CaCO_3$ formation between GCC in aqueous medium made high bulk paper without harming tensile strength, bulk, opacity, and smoothness. The GCC that has equivalent size as HCC failed to make high opacity and smoothness as much as HCC.

• Journal of the Korean Wood Science and Technology
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• v.20 no.4
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• pp.57-64
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• 1992

The unique cell wall micropores of pulp fiber can be utilized as loading site in variety of important practical application which could be the basis of new papermaking technologies. One of these includes the manufature of paper containing higher levels of in situ filler precipitated. Hardwood pulp fiber were first impregnated with the solution of sodium carbonate($Na_2CO_3$). The micropores in cell wall of pulp fibers were filled with the liquid salt solution. The second calcium nitrate($Ca(NO_3)_2$) solution formed an insoluble calcium carbonate($CaCO_3$) precipitate within the cell wall micropores by interacting with the first sodium carbonate solution. The effects of chemical concentration and dryness of pulp fibers on the retention of cell wall micropore loaded filler were investigated. The paper properties of cell wall micropore loaded pulp fibers were compared with those of conventionally loaded and lumen loaded pulp fibers. Also the presense of the fillers within the cell wall micropore was observed by SEM. Increasing the chemical concentration to generate the calcium carbonate increased the retention of filler in cell wall micropore loaded pulp fibers. The particle size distribution of precipitated calcium carbonate ranged from $0.1{\mu}m$ to $80{\mu}m$. But, the average particle size of cell wall micropore loaded calcium carbonate was $4{\mu}m$. The paper made from never dried pulp fibers, the cell wall micropores which were filled with calcium carbonate, had better mechanical and optical properties than those of conventionally loaded or lumen loaded pulp fibers.

• Resources Recycling
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• v.19 no.3
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• pp.62-70
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• 2010

As the demand for paper continues to grow and the importance of recycled paper, white ledgar(WL) and old newspaper pulp(ONP), continuously increase. In addition, usage of recycled paper is essential in terms of forest conservation and environmental protection issues. However, optical and mechanical properties of recycled paper have some drawbacks than regular paper's properties that is indispensable. In order to complement these problems of recycled paper, precipitated calcium carbonate (PCC) was synthesized by the In-situ process with a recycled pulp. Depending on the size of PCC is divided into 2 types, $0.01{\mu}m{\sim}0.09{\mu}m$ colloid type ultra-fine particle and $0.1{\mu}m{\sim}0.9{\mu}m$ cubic type particles. In this study, we analyze how the different shape and size of precipitated calcium carbonate affects in the optical and mechanical properties of the recycled paper used as a filler. Furthermore, we mixed with chemical pulp for overcome reduce of mechanical properties, without using other chemicals, when we use PCC as a filler. The results has the possibility to meet in GR excellent recycling certification mark, standard was proposed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.19-26
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• 2014

In-situ $CaCO_3$ formation on recycled wood pulp was studied to improve optical property and filler attachment to the fiber furnish in papermaking. We tried to attach calcium oxide (CaO) to the recycled fibers, old newspaper (ONP) in this case, by using selected polymers before in-situ $CaCO_3$ formation reaction on fibers, and then, $CO_2$ was injected to the furnish until all the CaO on fiber surfaces was consumed. It was found that the attachment of newly formed $CaCO_3$ to recycled fibers became stronger by attaching CaO to the fibers before in-situ $CaCO_3$ formation reaction. It was expected that the polymers used for the attachment of calcium source to the fiber furnishes helped to keep the newly formed $CaCO_3$ strongly attached to the fiber surface as well as to retain the impurities associated with calcium source and recycled fibers, if any. In-situ $CaCO_3$ formation gave higher brightness and much less ERIC value in ONP sheet than the case when the equivalent amount of GCC was added to the furnish.

• Macromolecular Research
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• v.17 no.12
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• pp.1032-1038
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• 2009

A polypyrrole (PPy)/alumina composite filler prepared via in-situ polymerization of pyrrole on alumina particles was incorporated into $Nafion^{(R)}$ to improve the performance of ionic polymer-metal composite (IPMC) actuators. The IPMCs with the pristine PPy without alumina support did not show bending displacements superior to that of the bare Nafion-based IPMC, except at a high PPy content of 4 wt%. This result was attributed to the low redox efficiency of the PPy alone in the IPMC and may have also been related to the modulus of the IPMC. However, at the optimized filler contents, the cyclic displacement of the IPMCs bearing the PPy/alumina filler was 2.2 times larger than that of the bare Nafion-based IPMC under an applied AC potential of 3 Vat 1 Hz. Even under a low AC potential of 1.5 V at 1 Hz, the displacement of the PPy/alumina-based IPMCs was a viable level of performance for actuator applications and was 2.7 times higher than that of the conventional Nafion-based IPMC. The generated blocking force was also improved with the PPy/aiumina composite filler. The greatly enhanced performance and the low-voltage-operational characteristic of the IPMCs bearing the PPy/alumina filler were attributed to the synergic effects of the neighboring alumina moiety near the PPy moiety involving electrochemical redox reactions.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.72-74
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• 2003

There has been extensive interest in the development of new nanocomposites. One kind of these systems is the hybrid based on organic polymers and inorganic minerals consisting of layered silicates. Some properties like stiffness, strength, barrier properties, thermal, and oxidative stability can be improved by the presence of the filler in the polymeric matrix[1]. It is reported that, in the nylon 6/clay nanocomposites, the modulus is increased, but impact strength and elongation at break are drastically decreased. (omitted)

• Journal of the Korean GEO-environmental Society
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• v.21 no.9
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• pp.25-32
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• 2020

The underground utilities installed under the ground is an important civil engineering structure, such as water supply and sewerage pipes, underground power lines, various communication lines, and city gas pipes. Such underground utilities can be exposed to risk due to external factors such as concentrated rainfall and vehicle load, and it is important to select and construct an appropriate backfill material. Currently, a method mainly used is to fill the soil around the underground utilities and compact it. But it is difficult to compact the lower part of the buried pipe and the compaction efficiency decreases, reducing the stability of the underground utilities and causing various damages. In addition, there are disadvantages such as a decrease in ground strength due to disturbance of the ground, a complicated construction process, and construction costs increase because the construction period becomes longer, and civil complaints due to traffic restrictions. One way to solve this problem is to use a liquid filler. The liquid filler has advantages such as self-leveling ability, self-compaction, fluidity, artificial strength control, and low strength that can be re-excavated for maintenance. In this study, uniaxial compression strength test and fluidity test were performed to characterize the mixed soil using marine clay, stabilizer, and in-situ soil as backfill material. A freezing-thawing test was performed to understand the strength characteristics of the liquid filler by freezing, and in order to examine the effect of the filling materials on the corrosion of the underground pipe, an electrical resistivity test and a pH test were performed.