• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.57-64
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• 1999

This research was carried out to investigate the effects of density, resin and particle types on the physical and mechanical properties of the composites made from various wood particles mixed with coating paper. The experiment was designed to apply with three particles (flake, chip, and fiber) and three resin types (urea, phenol and PMDI resin). The mixed ratio of coating paper to wood particle was fixed on 50 to 50% in each board making. And also it was designed to apply for four density levels (0.6, 0.7, 0.8 and 0.9 g/$cm^3$) and four mixed formulations of coating paper to wood particle (10:90, 20:80, 30:70, and 40:60 %) to analyze clearly the effects of PMDI resin. Coating paper-wood particle composites have acceptable bending strength (MOR, MOE) though the mixed ratio of coating paper was increased, but have low internal bond strength and poor dimensional stability (WA, TS, LE). Composites with high density had higher mechanical properties but showed lower physical properties than composites with low density. In conclusion, at least up to 20% mixed ratios, coating paper-wood particle composites have acceptable physical and mechanical properties, and PMDI resin has possibility for coating paper-wood particle composite manufacture.

• Carbon letters
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• v.12 no.4
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• pp.243-248
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• 2011

Two different types of graphite, such as flake graphite (FG) and spherical graphite (SG), were used as anode materials for a lithium-ion secondary battery in order to investigate their electrochemical performance. The FG particles were prepared by pulverizing natural graphite with a planetary mill. The SG particles were treated by immersing them in acid solutions or mixing them with various carbon additives. With a longer milling time, the particle size of the FG decreased. Since smaller particles allow more exposure of the edge planes toward the electrolyte, it could be possible for the FG anodes with longer milling time to deliver high reversible capacity; however, their initial efficiency was found to have decreased. The initial efficiency of SG anodes with acid treatments was about 90%, showing an over 20% higher value than that of FG anodes. With acid treatment, the discharge rate capability and the initial efficiency improved slightly. The electrochemical properties of the SG anodes improved slightly with carbon additives such as acetylene black (AB), Super P, Ketjen black, and carbon nanotubes. Furthermore, the cyclability was much improved due to the effect of the conductive bridge made by carbon additives such as AB and Super P.

• Journal of Korea Game Society
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• v.3 no.1
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• pp.3-9
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• 2003

This paper deals with animation of snowy scenery using texture mapping and particle system. Two different OpenGL programs were prepared and compared for implementation and evaluation of their performance. One used glPointSize(), and the other used glut SoildSphere(). Result of implementation revealed that the first was faster than the second. So the first is considered to be more useful for the slow PC. In relation to the first method, I found that control of shape of snow flake conflicts with that of color. Fortunately, I found out an esoteric method which handles the back ground image for scene that is used in texture mapping, I present that method.

• Journal of the Korean Magnetics Society
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• v.11 no.1
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• pp.8-13
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• 2001

Effects of casting Processes and lubricant addition were studied to improve remanence of 31RE-68TM-lB based sintered magnet by using axial pressing process. Strip casting was effective to get the fine and homogeneous microstructure without ${\alpha}$-Fe segregation. The strip cast flake resulted in narrower particle size distribution after jet milling with respect to the conventional cast ingot. During pressing step with a magnetic field, the particle alignment was increased by appropriate addition of liquid lubricant. In this study, it was revealed that narrow particle size distribution and appropriate addition of liquid lubricant were essential to improve the grain alignment and thus the remanence of Nd-Fe-B sintered magnet.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.39-41
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• 2011

The recycling rate of recovered paper in Korea is the highest in the world, 92%, but remanufacturing yield is low due to the extremely poor quality of the paper. The poor quality, in turn, influences to the reject amount in deinking process. To increase the yield of old newspaper recycling process, hydrophobic degree of inorganic pigments of deinking stock must be reduced. To determine the hydrophobicity, Pitch Potential Deposit Tester (PDT) was newly designed and applied with respect to the SB latex property of various quality used in Korea; its hydrophobic degree according to Tg, gel content, charge and particle size of latex and optimum designing condition of SB latex. And below are the conclusions: 1. The reason of excessive reject from old newspaper deinking process for total amount of printed ink is loss of inorganic pigments. When lipase, a biochemical catalyst, was applied with the purpose of preventing inorganic pigments loss about more than 70% of total reject weight and promoting hydration of pulp for deinking, deinking process yield of pre flotation secondary stage increased remarkably without any changes of deinking efficiency. 2. Lipase improved deinking stock by cutting ester linkage on surface of hydrophobic materials to promote its hydration. From this, it reached the conclusion that hydration degree of stock exercises significant effect on flotation deinking process yield. 3. Inorganic alkali promotes hydration of deinking stock. But there have been needs for more fundamental measures other than inorganic alkali of promoting hydration for yield improvement. For this, this study intended to find out reasons of chemical properties change on surface of hydrophobic material by change of pH. 4. Pitch Deposit Test (PDT) was performed for understanding principle of why surface of coating flake from OMG is hydrophobic and why it becomes hydrophilic when pH of stock is alkaline. As a result of this test, it is determined that swelling property by change of pH of latex film, which were used as coating adhesive is the reason for hydrophobic change. 5. Hydrophilicity of coating flake increased with hydrophilic pigments. And as more of SB Latex adhesive was used and higher of calcium hardness of stock became, its hydrophilicity decreased. SB Latex adhesive film is reformed by mechanical friction. For having hydrophilicity under neutral pH, strong bruising action such as kneading is required. 6. Because swelling of adhesive film decreases as Tg of SB latex gets lower and mean diameter gets smaller, it shows hydrophobicity under neutral pH. This lowers hydrophilicity of coating flake, which leads to easy elimination with flotation reject on DIP process. Therefore, for improving future flotation yield, it is necessary to develop to use eco-friendly clean SB latex by raising Tg and increasing mean diameter for recycling, and as a result, to reduce excessive loss of coating flake as a reject from deinking process.

• Food Science and Preservation
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• v.12 no.1
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• pp.62-67
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• 2005

Microwave-assisted extraction (50 W, 2,450 MHz, MAE) with properties of selective heating and subsequent extraction for certain phytochemicals from natural materials was applied to pre-establish the extraction conditions for total yield total phenolics, and electron donating ability (EDA) from Brossica oleacea. The experiments with $50\%$ EtOH solvent showed that 20 mesh in particle size of cabbage flake $(moisture\;4.5\%)$ and 1:10 (g/mL) in the sample to solvent ratio for both raw $(moisture\;90.2\%)$ and flake cabbages were optimal for MAE efficiency. Under these conditions, total yield increased with extraction tim, which was highest for raw cabbage extract in $50\%\;EtOH$ solvent followed by $100\%\;EtOH$ and water. While that of flake cabbage extracts was highest in $50\%\;EtOH$ followed by water and $100\%\;EtOH$. The contents of total phenolics and EDA in extracts gradually increased after 3 min of MAE, which were highest when using $100\%\;EtOH$ solvent followed by $50\%\;EtOH$ and water in raw cabbage and $50\%\;EtOH$ followed by water and $100\%\;EtOH$ in flake cabbage, respectively.

• Composites Research
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• v.30 no.3
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• pp.181-187
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• 2017

The effect of nanoscopic and microscopic Fe, $Fe_3O_4$, and Ni particles and their shapes and substrate materials on the heating behavior of thermoplastic polyurethane (TPU) adhesive films was investigated via induction heating. The heat generation tendency of $Fe_3O_4$ particles was higher than that shown by Fe and Ni particles in the TPU adhesive films. When the Fe and Ni particle size was larger than the penetration skin depth, the initial heating rate and maximum temperature increased with an increase in the particle size. This is attributed to the eddy current heat loss. The heating behavior of the TPU films with Ni particles of different shapes was examined, and different hysteresis heat losses were observed depending on the particle shape. Consequently, the flake-shaped Ni particles showed the most favorable heat generation because of the largest hysteresis loss. The substrate materials also affected the heating behavior of the TPU adhesive films in an induction heating system, and the thermal conductivity of the substrate materials was determined to be the main factor affecting the heating behavior.

• Analytical Science and Technology
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• v.23 no.2
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• pp.216-223
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• 2010

In previous research, results on efficiency versus size and type of Ag particles showed similarity of detection efficiency comparing the particles of flake and spherical type with the gray particle on the market and in the case of nAg (rod, $0.9\;{\mu}m$) particle, relatively good results was given in the various evaluation methods for detection efficiency of latent fingerprint. However, oxidation was occurred when nAg particles laying on nature condition for a month and due to water absorption, detection efficiency was decreased. Therefore, with need to prevent oxidation and water absorption, more research is necessary. In this research, surface modification on nAg particles using silicon oil was conducted in various methods for complementing weakness of oxidation and water absorption. Then detection efficiency of nAg particles and surface modified nAg particles was evaluated by the number of feature points on the surface of non-porous materials (glass, plastic etc.) and degree of particle adhesion with ridges and contrast of detected fingerprint. Improvement of preventing oxidation and water absorbtion was given by surface modification using silicon oil (DC200, 0.5%) on the surface of non-porous materials.

• Journal of the Korean Magnetics Society
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• v.14 no.4
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• pp.131-137
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• 2004

For the aim of thin electromagnetic wave absorbers used in mobile telecommunication frequency band (0.8-2.0㎓), we investigate high-frequency magnetic, dielectric and microwave absorbing properties of iron particles dispersed in rubber matrix in this study. The major experimental variables are particle shape (sphere and flake) and initial particle size (in the range 5-70 $\mu\textrm{m}$) of iron powders. High value of magnetic permeability and dielectric permittivity can be obtained in the composites containing thin plate-shape (flake) iron particles (of which thickness is less than skin depth in ㎓frequency), which can be produced by mechanical forging of spherical iron powders using an attrition mill. This result is attributed to the reduction of eddy current loss (increase of permeability) and the increase of space charge polarization (increase of permeability). The optimum initial particle size is found to be about 10 $\mu\textrm{m}$ for the attainment of the material parameters (particularly, real part of complex permeability) satisfying the wave impedance matching. With the iron powders controlled in size and shape as absorbent fillers in rubber matrix, the thickness can be reduced to about 0.7mm with respect to -5㏈ reflection loss (70% power absorption) in mobile telecommunication frequency band.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.2049-2054
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• 2013

Recently, magnesium hydroxide ($Mg(OH)_2$) has many applications in various field, due to its outstanding characteristics such as a nontoxic, noncorrosive and thermal stable properties. In this study, different shapes of flower and flake type magnesium hydroxide were synthesized by precipitation method at room temperature using $MgSO_4$, $MgCl_2$ and $Mg(NO_3)_2$ as magnesium sources, NaOH and $NH_3$ as alkaline sources. Influence of synthesis on the morphological characteristics, sizes and shapes of magnesium hydroxide particles, was investigated, such as different precursors and parameters. The shape of magnesium hydroxide depend on magnesium and alkali sources. Average size of flower particle had about $1{\mu}m$, and flake had about 20 ~ 50 nm. The synthesised magnesium hydroxide groups were characterized by XRD, FE-SEM, FT-IR, EDS, PSA and TG.