• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.135-143
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• 2015

This study evaluated fuel properties of composite materials which were prepared by mixing a waste activated carbon from the used purifier filter with torrefied wood powder. Wood species of the raw material of torrefied wood powder are oak wood (Quercus serrata Thunb. ex Murray) and pine wood (Pinus densiflora Siebold & Zucc). And the treatment conditions used for this study were 300 s, 450 s, and 600 s at $200^{\circ}C$ for the wood roaster. Also, the mixing ratios are 5 : 95, 10 : 90, 15 : 85, 20 : 80, 40 : 60, 60 : 40 and 80 : 20 (waste activated carbon : torrefied wood powder). The fuel properties such as highly heating value (HHV), elementary analysis and ash content were evaluated. The results obtained are followings; 1. Despite the same treatment condition of wood roasting, pine wood has higher carbon contents than oak wood. Therefore, pine wood indicated the optimum carbonization at low temperature and short treatment times. 2. The gross calorific value and ash content increased as the mixing ratio of waste activated carbon increased. 3. Mixtures of the waste activated carbon and torrefied wood powder showed greater gross calorific value than those of the mixtures of waste activated carbon and the untreated wood powder. Also, the pine wood resulted in higher heating value that thaose of the oak wood. 4. When composite fuels that were composed waste activate carbon and wood powder are used, higher temperature conditions are required because the combustion is incomplete at $800^{\circ}C$ and 4 hours. 5. The increasing rate of the gross calorific value of mixtures of waste activated carbon and untreated wood powder is higher than does the mixtures of waste activated carbon and torrefied wood powder. Also, this phenomenon is more obvious for pine woods. Therefore, an optimal mixing ratio of waste activated carbon was determined to be between 5% and 10% (wt%). Also, this condition satisfied the requirement of the No.1 grade of wood pellet.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.1
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• pp.85-95
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• 1998

The broadband ultrasonic transducers have been designed to use in obtaining the broadband echo signals from fish schools in relation to the identification of fish species. The broadening of bandwidth was achieved by attaching double acoustic matching layers on the front face of a Tonpilz transducer consisted of an aluminum head, a piezoelectric ring, a brass tail and to evaluate the performance characteristics, such as the transmitting voltage response(TVR) of transducers. The constructed transducers were tested experimentally and numerically by changing the parameters such as impedances and thicknesses of the head, tail and matching layers, in the water tank. Also, the developed transducer was excited by a chirp signal and the received chirp waveforms were analyzed. According to the measured TVR results, the available 3 dB bandwidth of the transducer with double matching layers of an $Al_O_3/epoxy$ composite of 7 mm thick and a polyurethane window of 18 mm thick was 7.3 kHz with a center frequency of 38.8 kHz, and the maximum and the minimum values of the TVR in this frequency region were 135.7 dB and 132.7 dB re $1\;{\mu}Pa/V$ at 1 m, respectively. Also, the available 3 dB bandwidth of the transducer with double matching layers of an $Al_O_3/epoxy$ composite of 11 mm thick and a polyurethane window of 15 mm thick was 6.2 kHz with a center frequency of 38.6 kHz, and the maximum TVR value in the frequency region was 136.3 dB re $1\;{\mu}Pa/V$ at 1 m. Reasonable agreement between the experimental results and the numerical results for the TVR of the developed transducers was achieved. The frequency dependant characteristics of experimentally observed chirp signals closely matched to the measured TVR results. These results suggest that there is potential for increasing the bandwidth by varying other parameters in the transducer design and the material of the acoustic matching layers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.93-99
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• 2019

The purpose of this study was to investigate the bond strength between PEKK(Polyetherketoneketone) and Sinfony(3M ESPE, Seefeld, Germany) the dental composite resin by proposing the three representative surface treatment methods and evaluate to see if they affect the bond strength between two materials. A total of 30 PEKK($Pekkton^{(R)}$ Ivory, $Cendres+M{\acute{e}}taux$, Bienne, Switzerland) specimens were prepared, embedded in acrylic resin, polished(P 1200 grid) to surface, and each group was divided into 10 specimens. After then, by the surface treatment method, it classified into three groups(n=10) such as Air abrasion group(PN), applying Single Bond Universal(3M ESPE) after Air abrasion(PB), applying OPAQUE(3M ESPE) after Air abrasion(PO). Then, veneering was performed by using Sinfony(3M ESPE, Seefeld, Germany). All completed specimens were allowed to rest in a $37^{\circ}C$ water bath for 24 hours. Shear bond strength of each group was measured and fracture patterns were classified. Statistic analysis was performed with One-way ANOVA followed by post hoc Scheffe tast (p<.05). Statistical analysis was performed using the SPSSWIN 21.0 program. As a result of one-way ANOVA, the average value of PB group was $27.67{\pm}4,18MPa$ and it was shown as the highest bond strength, PN and PO were $20.43{\pm}1.70$ and $19.8{\pm}4.77MPa$ each, and these were relatively low(F=18.4, P<.001), and as the post-test the Scheffe test was conducted and verified (p<.05). After examining the scheffe test, it was showed significant differences as PB>PO, PB>PN(p<.001). Through this study, in order to enhance the bonding force between PEKK and the composite resin, perform the Air abrasion and surface treatment by using Single Bond Universal(3M ESPE) is recommended, and as coMPared with other studies. And it is assumed that the increase of the application time of the Air abrasion affects the increase of the shear bond strength. Thus, further research is required.

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.342-349
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• 2018

In this study, the physicochemical properties, emulsifying capacity, moisture content and cytotoxicity of the composite material produced by transesterification reactions of the olive oil (olive oil esters) were investigated for cosmetic applications. Olive oil esters with short (S) and long (L) reaction times were studied. From the TLC-image analysis, composition ratios of the olive oil esters S were found to be 5.2, 24.1, 46.4, and 21.9% for mono-, di-, tri-glyceride, and fatty acid ethyl ester, respectively. Those of the olive oil esters L were 4.1, 24.7, 40.6, and 28.8% for mono-, di-, tri-glyceride, and fatty acid ethyl ester, respectively. The iodine value, acid value, saponification value, unsaponified matter, refractive index, and specific gravity were determined and purity tests were also carried out and normalized to establish standards and testing methods for using olive oil esters in cosmetics. To evaluate their emulsifying capacities, the O/W emulsion was prepared without surfactants and the formation of the emulsified particles were confirmed. After 5 days of applying the olive oil esters to human skin, the skin moisture retention was improved by 13.1% from the initial state. For the evaluation of toxicity on human skin cells, the olive oil esters showed 90% or more of the cell viability at $0.2-200{\mu}g/mL$. These results suggested that olive oil esters can be applied as natural/non-toxic ingredients to cosmetics industries.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.260-265
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• 1999

$SiC/Si_3N_4$ composites were prepared by mixing ${\alpha}-Si_3N_4$ powder to $\alpha$-SiC powder in the range of 10 to 30 vol% with 10 vol% interval. 6 wt% of $Al_2O_3$ and $Y_2O_3$ were also added respectively as sintering aids. Then, pressureless sintering was performed at 1,78$0^{\circ}C$ for 2 hours in $N_2$ gas. In the case of adding 20 vol% of ${\alpha}-Si_3N_4$ powder, the relative desity to theoretical value and the flexutal strength were 92 % and 3,560 MPa, respectively. The smallest relative worn amount thereof was $2.68{\times}10^{-3}\;mm^2$ for 20 vol% ${\alpha}-Si_3N_4$. The composite containing 30 vol % of ${\alpha}-Si_3N_4$ powder showed the highest fracture toughness $(K_{1c})$ of $4.9\;MN/m^{3/2}$, although the reduction of the wear resistance due to the effect of the pores was observed.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.173-182
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• 2017

This study was conducted to investigate the change of Aaster scaber antioxidative activity, total phenolic compounds and flavonoids during the blanching processes. With two parameters such as blanching time and temperature, response surface methodology and central composite design was used to study the combined effect of blanching time (90 to 162 sec) and blanching temperature (75 to $99^{\circ}C$). We found that antioxidative activity, total phenolic compounds and flavonoids during the blanching processes were influenced by blanching temperature and time. Within process condition, total phenolic compounds and flavonoids were extracted 3.00 - 35.48 mg/g and 2.35 - 8.38 mg/g, respectively. DPPH radical scavenging activity was 42.10 - 67.14%. The change of total phenolic compounds, flavonoids, and DPPH radical scavenging activity was dependent of blanching temperature more than time. The total phenolic compounds was increased as temperature rise, but flavonoids not. However, DPPH radical scavenging activity was increased during the blanching process.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.50-57
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• 2017

Zinc oxide is, one of metal oxide semiconductor, harmless to human and environment-friendly. It has excellent chemical and thermal stability properties. Wurtzite-zinc oxide is a large band gap energy of 3.37 eV and high exciton binding energy of 60 meV. It can be applied to various fields, such as solar cells, degradation of the dye waste, the gas sensor. The photocatalytic activity of zinc oxide is varied according to the particle shape and change of crystallinity. Therefore, It is very important to specify the additives and the experimental variables. In this study, the zinc oxide were synthesized by using a microwave assisted hydrothermal synthesis. The precursor was used as the zinc nitrate, the pH value was controlled as 11 by NaOH. Surfactants are the ethanolamine, cetyltrimethylammonium bromide, sodium dodecyl sulfate, sorbitan monooleate was added by changing the concentration. The composite particles had the shape of a star-like, curcular cone, seed shape, flake-sphere. Physical and chemical properties of the obtained zinc oxide was characterized using x-ray diffractometer, field emission scanning electron microscopy, thermogravimetric analysis and optical properties was characterized using UV-visible spectroscopy, photoluminescence and raman spectroscopy.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.116-124
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• 2017

A plate-type inorganic pigment complex was manufactured in a manner that treats the surface of the complex by adjusting zeta potential between talc, an inorganic pigment used as a material for color cosmetics, and hydrophobic silica. Talc, which is usually used in the prescription of color cosmetics, is a plate-type, white-colored inorganic substance with good application and spreadability to skin. Furthermore, it features excellent dispersibility and extensibility as well as outstanding heat tolerance, light stability, and chemical resistance. In general, silica contributes to durable makeup and stabilized formulation. This paper covers a process of manufacturing an inorganic pigment complex, where hydrophobic silica was applied to the surface of talc by using differences in zeta potential after the surface charges of talc and hydrophobic silica had been adjusted with cationic and anionic surfactants, respectively. The resulting inorganic pigment complex was composed of talc whose surface is coated hydrophobic silica to the thickness of $1{\mu}m$ or less, which developed an effective hydrophobic property. Zeta potential was measured to analyze the surface charge of an inorganic pigment, and FT-IR, used to check the functional group of a surfactant, was applied to treat the surface of the pigment. The surface of the inorganic pigment complex was observed employing SEM, EDS, and FIB, while its structure was confirmed with XRD and FT-IR.

• Science of Emotion and Sensibility
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• v.20 no.2
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• pp.117-126
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• 2017

In this study, moisture transport characteristics for the woven and knitted fabrics made of 8 kinds of fiber materials using MMT (moisture management tester) were measured and discussed with the Bireck bt MMT and water evaporating rate (WER) measuring methods, which are vertical moisture transport methods. In addition, the drying property by MMT of the eight kinds of specimens was compared and discussed with the results measured by the vertical drying measurement. MMT experimental result which is horizental moisture transport appeared to be similar to the result of the Bireck method, which is the vertical moisture transport experiment. Absortion time measured from drip method of the fabrics made of the bamboo, linen, and cotton/nylon composite fabrics was short and thus they showed best wicking property, which was attributed to the low contact angle on the fabric surface and high porosity of the fabrics due to the staple yarn structure composed of the hydrophilic staple fibers. In drying property of the fabric specimens by MMT, maximum absorption radius of the dry-zone knit and bamboo woven fabrics were the highest and they showed the best drying property, which was a little different result compared with vertical drying measurement method. Half time of the drying rate in the MMT method was highly correlated with the fabric thickness and saturated moisture absortion rate and their regression coefficients were 0.9 and 0.88, respectively. This means that the knitted and woven fabric design technology for retaining good wicking and drying properties of the fabrics with thin fabric thickness is very important for obtaining high functional wear comfort fabrics. In addition, wicking and drying properties of the fabrics made of different fiber materials and with different yarns and fabric structures showed different results according to the measuring methods.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.622-627
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• 2009

The objectives of this study were to evaluate a protease suitable for the enzymatic hydrolysis of a snow crab processing by-product (SPB) and to optimize the hydrolysis conditions using response surface methodology (RSM). The SPB was hydrolyzed at $50^{\circ}C$ and pH 7.0-7.2 to obtain various degree of hydrolysis (DH) using Flavourzyme at an enzyme/substrate (E/S) ratio of 3.0%. The reaction progress curve exhibited an initial fast reaction rate followed by a slowing of the rate. The DH was increased to 30% at 90 min with a final DH 32 to 36%. A central composite experimental design having three independent variables (reaction temperature, reaction time, and E/S ratio) with five levels was used to optimize the enzymatic hydrolysis conditions. Based on the DH data, the optimum reaction conditions for the enzymatic hydrolysis of the SPB were a temperature of $51.8^{\circ}C$, reaction time of 4 hr 45 min, and an E/S ratio of 3.8%. It was demonstrated that the enzymatic hydrolysate of SPB could be used as a flavoring agent or a source of precursors for the production of reaction flavors.