• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.8-15
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• 2014

The increase of wet web solid content in wet pressing will save drying energy greatly. We applied wood flours as spacers to increase the old corrugated container (OCC) solid contents in wet pressing. The mixed furnish of OCC and wood flours of 3-5% (wt/wt) increased bulk and drainage rate, and by increasing wet pressing pressure, its solid content started to be higher than 100% OCC furnish at more than 50% solid content level. Addition of cationic starch and drainage aid to the mixed furnish increased solid content further up to around 2%. Cationic starch addition compensated or exceeded the loss of tensile and compressive strength caused by the addition of wood flour, but drainage aid did not. Cationic starch also improved the stretch of the OCC, which could mitigate cracking at folding in boxboard.

• Resources Recycling
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• v.8 no.4
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• pp.57-63
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• 1999

Wood-Polymer Composites (WPC) m s prepared irom recycled films of agricullural use and wood wastes, and LLDPE and neal PE resin mlxlurr war also utilized in order to cornpiue the praperlies. Molc~ca nhydride (MA) and dicumyl peroxide were used as an adheslon pmmoler and an il~lliatotor~, .espcmivelyT. ensile prapenies of W Cw zrc measured via lenslle test as a funclieu of woad lille~m d MA contmt, and rractu1.e surface was also mvestigaled wilh SEM. As the content of wwd tiller mcreased, clongauon deneased bul modulus increased However, tensile slrength OI WPC increased only when MA war used, and 1 wt.% of MA may be hgh enough to increase the tensile properties. The tensilc ptopcrlies af WPC prepwed from recycled PE films were &nost same as thosc of neal PE resin mixture.

• Textile Coloration and Finishing
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• v.24 no.4
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• pp.281-287
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• 2012

Poly(phenylene sulfide) films containing acetophenone as a photoinitiator were photocrosslinked under UV irradiation using a continuous UV irradiator. The gel fraction of the irradiated PPS in 1-Chloro naphthalene reached 94.7% with increasing UV energy and the photoinitiator concentration in the film upto $200J/cm^2$ and 12wt% respectively. Solid state $^1C$ NMR analysis suggested that the crosslinking occurred between the phenylene chains in PPS, indicating that the acetophenone may the phenylene hydrogens and subsequently adjacent polymer radicals could be recombined to form the crosslinked structure. The crosslinking improved the thermal behavior of PPS such as loss of $T_g$ and $T_c$, higher melting point and lower melting enthalphy as well as significantly higher peak pyrolysis temperature as much as $63.5^{\circ}C$. Surprisingly the tensile toughness of the most crosslinked PPS increased by 842%, resulting from the substantial enhancements in tensile modulus, strength and strain as much as 76%, 236% and 240% respectively. Also dynamic mechanical measurement indicated that the distance between crosslinks in the crosslinked PPS reached 85.3 g/mol corresponing to a crosslink density of 0.012 mol/g.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.41-47
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• 2012

Multi-walled carbon nanotubes (MWCNTs) incorporated polyacrylonitrile (PAN) and poly (methyl methacrylate) (PMMA) nanofibers were synthesized using electronspinning method. Effects of polymer concentration and applied voltage on the synthesis of PAN and PMMA nanofibers were systematically investigated. The structural characterization of PAN/MWCNTs and PMMA/MWCNTs composited nanofibers synthesized as a function of the MWCNTs concentration was performed by scanning electron microscopy and transmission electron microscopy. 5 wt% MWCNTs incorporated PAN and PMMA electrospun nanofiber exhibit best strength and stiffness.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.43-49
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• 2002

A7003 alloy has characteristics of their excellent weldability, high corrosion resistance and superior plastic working however the broadening of application for the alloy has been hampered by the lower extrudability associated by Mg content. For improvement of extrudability and enhanced recovery efficiency during Al scrap recyeling, it has been generally practiced to reduce Mg content in A7003 alloy. Therefore, it is necessary to investigate the influence of Mg content on mechanical strength and extrudability of A7003 alloy. For efficient material processing which has small amounts, life cycle assessment in material processing(MLCA) is evaluated. The quantitative analysis of energy requirements and $CO_2$ emission for production of A7003 extruded bar are estimated with different Mg content and billet pre-heating process (heating source by light oil or LPG). In particular, the estimation of energy requirements was performed within shipping and gating range (except the mining and extraction stages)to investigate the influence of the variables on energy requirements and $CO_2$ emission in detail. As Mg content increased, the flow stress and the extrusion pressure for A7003 alloy increased. It has been thought that an increment in extrusion pressure with increasing Mg content is caused by the solid solution hardening of Mg atoms in the matrix and increment in volume fraction of intermetallic compound, $Mg_2Si$. The extrudability and the tensile strength are equal to, or above that of conventional A 7003 alloy even the content of Mg varied from $1.1wt.\%\;to\;0.5wt.\%$ alloy. This means that minimizing the content of Mg in A7003 alloy can enhance recovery efficiency during Al scrap recycling. It can be quoted that rather than Mg content energy source for billet heating is a prime factor to determine the atmospheric $CO_2$ emission.

• Polymer(Korea)
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• v.35 no.1
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• pp.13-16
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• 2011

In this study, the hydrogels composed of polyvinylpyrrolidone (PVP), ${\kappa}$-carrageenan (${\kappa}C$), and 1,2-hexanediol (HD) were prepared by ${\gamma}$-ray irradiation. The radiation dose was 25 kGy and the concentration of ${\kappa}C$ was 3 wt%. The physical properties of the hydrogels were investigated as a function of the concentrations of PVP and HD. The gel content and the tensile strength increased with increasing PVP concentration due to the crosslinking between the pyrrolidone molecules and decreased with increasing HD concentration. The degree of swelling was inversely proportional to the gel content because the highly crosslinked hydrogels had a tighter structure, hence reducing their water absorption. The antibacterial tests indicated that the hydrogels containing HD had antibacterial activity.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.561-569
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• 2014

Ceria ($CeO_2$) was used to increase the durability of the membrane in the polymer electrolyte membrane water electrolysis (PEMWE) circumstance. The sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK) to improve electrochemical characteristics. After sulfonation reaction, the organic-inorganic blended composite membranes were prepared by means of sol-gel casting method with loading the highly dispersed $CeO_2$ and Cs-substituted molybdophosphoric acid (Cs-MoPA) with cross-linking agent (tetrapropyl orthosilicate). Consequently, the composite membrane CL-SPEEK/Silane 4wt%/Cs-MoPA/Ceria(1%) showed the improved characteristics such as 82% of water content, 0.11136 S/cm of proton conductivity at $80^{\circ}C$, 55.50 MPa of tensile strength and 4.37% of breeding out of MoPA.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.525-530
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• 2023

Stretchable piezoelectric energy harvester (S-PEHs) based on composite materials are considered one of the potential candidates for realizing wearable self-powered devices for smart clothing and electronic skin. However, low energy conversion performance and expensive stretchable electrodes are major bottlenecks hindering the development and application of S-PEHs. Here, we fabricated the S-PEH by adopting the piezoelectric composites with enhanced stress transfer properties and kirigami-patterned textile electrodes. The optimum contents of piezoelectric BaTiO₃ nanoparticles inside the carbon nanotube/ecoflex composite were selected as 30 wt% considering the trade-off between stretchability and energy harvesting performance of the device. The final S-PEH shows an output voltage and mechanical stability of ~5 V and ~3,000 cycles under repeated 150% of tensile strain, respectively. This work presents a cost-effective and scalable way to fabricate stretchable piezoelectric devices for self-powered wearable electronic systems.

• Korean Journal of Metals and Materials
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• v.50 no.1
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• pp.1-7
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• 2012

The fracture resistance and tensile properties of $Y_2O_3$ oxide dispersion strengthened steel containing 9 wt% Cr(9Cr-ODS) were measured at various temperatures up to $700^{\circ}C$. The fracture characteristics were compared with those of commercial E911 ferritic/martensitic steel. The strength of 9Cr-ODS was at least 30% higher than that of E911 steel at the test temperatures below $500^{\circ}C$. The strength difference between the two materials was almost diminished at $700^{\circ}C$. 9Cr-ODS showed cleavage fracture behavior at room temperature and unstable crack growth behaviors at $300^{\circ}C$ and $500^{\circ}C$. The J-R fracture resistance of 9Cr-ODS was much lower than that of E911 steel at all temperatures. It was deduced that the coarse $Cr_2O_3$ particles that were formed during the alloying process provided the crack initiation sites of cleavage fracture in 9Cr-ODS.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.65-75
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• 1992

0.4wt%C steel added with V and/or Nb were forged and followed by air cooling. The structure-property relationships were examined and multiple regression analysis was conducted to quantify the magnitudes of effects of microalloying elements on the properties of the steels. All material's tensile strength are greater than $70kg/\textrm{mm}^2$, so they are equal to or superior to Q/T material's(S45C). Their impact energies are less than 40J, so they are 50% of Q/T material's. Increasing the content of V from 0.10 to 0.15 wt% had brought improvement in UTS about 20% but with some sacrifice of impact energy. These were the results from the precipitation strengthening by fine dispersion of VC in ferrite, increment of pearlite volume fraction and decrement of pearlite interlamellar spacings. However, increasing the content of Nb from 0.05 to 0.l0wt % slightly improved UTS and impact energy. NbC precipitates were more effective in suppression of austenite grain coarsening than VC precipitates. Combined additions of V+Nb were more effective to bring impact toughness than sole addition. Optimum combination of strength and toughness was accomplished wish 0.4C-1. 19Mn-0.05S-0.12V-0.07Nb steel.