• Journal of Energy Engineering
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• v.22 no.3
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• pp.287-293
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• 2013

This study was carried out to diminish the formation of scale in boilers which is one of the defect elements when they are operating. The defect relating to scale can cause a fatal impact on the explosion of boilers due to the overheating of their tubes, or it can affect the flow of water inside boilers with its bad circulation and result in a disparity of water inside the equipment. Heat transfer in the scale is low comparing to the boiler material, so it can lead to energy losses and has also impact on the global warming. In 2005, the Korean government introduced a system which requires boiler users to install the equipment which can prevent or eliminate the formation of scale to improve the management of water quality in boilers. The study on the techniques for preventing or eliminating the formation of scale started in 1821 and since then subsequently there have been lots of similar studies. The first one was about the scale reduction using potato starch. Since an ultrasonic scale preventer developed by a scientist from a Russian acoustic institute was introduced in1993, a variety of equipment of this kind have been disseminated in Korea. There has been a need to demonstrate the condition for the best performances of such equipment. Boilers are mostly composed of the main body and 288 the tube with a circular curved surface. I carried out a demonstration study on a circular tube which affects the scale defect the most among the boiler components. As a result of it, I found out the fact that the ultrasonic wave needs to reach a certain level of sound pressure and frequency to affect the formation of scale.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.710-716
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• 2013

New and renewable energy sources have drawn attention because of climate change. Many studies have been carried out in waste-to-energy field. Fast pyrolysis of waste lignocelluosic biomass is one of the waste-to-energy technologies. Bubbling fluidized bed (BFB) reactor is widely used for fast pyrolysis of the biomass. In BFB pyrolyzer, bubble behavior influences on the chemical reaction. Accordingly, in the present study, hydrodynamic characteristics and fast pyrolysis reaction of waste lignocellulosic biomass occurring in a BFB pyrolyzer are scrutinized. The computational fluid dynamics (CFD) simulation of the fast pyrolysis reactor is carried out by using Eulerian-Granular approach. And two-stage semi-global kinetics is applied for modeling the fast pyrolysis reaction of waste lignocellulosic biomass. To summarize, generation and ascendant motion of bubbles in the bed affect particle behavior. Thus biomass particles are well mixed with hot sand and consequent rapid heat transfer occurs from sand to biomass particles. As a result, primary reaction is observed throughout the bed. And reaction rate of tar formation is the highest. Consequently, tar accounts for 66wt.% of the product gas. However, secondary reaction occurs mostly in the freeboard. Therefore, it is considered that bubble behavior and particle motions hardly influences on the secondary reaction.

• Economic and Environmental Geology
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• v.50 no.3
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• pp.225-238
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• 2017

In this study, two viable measures of mean length and cumulative thickness of sand layers as important spatial statistics responsible for optimal SAGD (Steam Assisted Gravity Drainage) location for oil sand development were compared. For the comparisons, various deposits composed of sand and clay media were realized using a geostatistical simulator and the extent of steam chamber is simulated using multiphysics numerical simulator (dualphase flow and heat transfer). Based on the spatial statistics of each realization and the corresponding size of simulated steam chamber, the representativeness of two candidate measures (cumulative thickness and mean length of permeable media) were compared. The results of the geostatistical and SAGD simulations suggest that the mean length of permeable media is better correlated to the size of steam chamber than the cumulative thickness. Given those two-dimensional results, it is concluded that the cumulative thickness of the permeable media alone may not be a sufficient criterion for determining an optimal SAGD location and the mean length needs to be complementarily considered for the sound selections.

• Korean Journal of Veterinary Service
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• v.25 no.3
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• pp.245-257
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• 2002

The gene encoding the HN protein from the CBP-1 strain, a heat stable Newcastle disease virus (NDV) isolated from diseased pheasants in Korea, was characterized by reverse transcriptase- polymerase chain reaction(RT-PCR) and the nucleotide and amino acid sequences were analyzed following cloning of the HN gene. In all of the NDV strains studied, a 1.75 kb size cDNA fragment for the HN gene was generated by RT-PCR and smaller specific band sizes harboring the internal portions of the HN gene were also detected by using four pairs of primers. The RT-PCR was sensitive enough to detect viral transcripts when the virus titer was above 25 hemagglutination units. The amplified 1.75 kb cDNA was cloned into a BamHI site of the pVL1393 Baculo transfer vector. The nucleotide sequences of the 1,758 bp HN gene from the CBP-1 strain were determined by the dye terminator cyclic sequencing method. The gene sequences were compared among the strains of CBP-1, Texas GB, Beaudette C, LaSota, B1 and Ulster. The homology of the CBP-1 HN gene to other HN variants was 97.8% to Texas GB, 98.4% to Beaudette C, 95.4% to LaSota, 95.6% to B1 and 90.2% to Ulster. As the deduced 577 amino acid sequences were compared among the strains, the homology for CBP-1 HN appeared to be 96.7% to Texas GB, 97.9% to Beaudette C, 95.5% to LaSota, 95.5% to B1 and 92.7% to Ulster. It was evident that the amino acid sequences included 5 sites for N-asparagine linked glycosylation and 12 cysteine residues. The three conserved leucine residues within the predicted transmembrane domain of the HN protein are amino acid 30, 37 and 44. The three antigenic sites on the HN protein of NDV are amino acids 347(Glu), 481(Asn) and 495(Glu). These data indicate that the genotype of the CBP-1 strain is more closely associated with the strains of Texas GB and Beaudette C than it is for the LaSota, B1 and Ulster strains.

• Fire Science and Engineering
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• v.23 no.6
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• pp.126-134
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• 2009

In an attempt to control the spalling in high strength concrete, spalling reducer was mixed to identify the effect and thermal characteristics of concrete beam member at high temperature. The member was manufactured in such as way of adding 40~60MPa of high strength concrete into spalling reducer, and then fire resistance performance were monitored under the ISO standard fire load condition in accordance with KS F 2257. As a result of test, fore rate performance of 40MPa beam without spalling reducer was 180minutes, 50MPa was 174minutes and 60MPa was 152minutes, indicating that 50MPa and 60MPa beam appeared 6~28minutes short to become a 3-hour rate. However, 50 and 60MPa beam mixed with spalling reducer appeared to have satisfied the requirements for 180minutes. A spalling was occurred in surface of 50 and 60MPa beam mixed without spalling reducer, while no spalling or surface failure was occurred with 50 and 60MPa beam mixed with spalling reducer. Thus polypropylene fiber mixed with the concrete proved to be effective, but viewing that the surface of 60MPa was peeled off partially, the steel fiber mixed appeared not to be effective for the beam more than 60MPa.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.727-736
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• 2017

In this study, the method of evaluation of moisturizing ability of cosmetics using specimens was studied as an alternative method of clinical tests. Cosmetic spreadability, surface drying, and moisture loss rate of four specimens (Japanese cake (Maru mochi), Garaetteok, wheat flour, and agar) were evaluated. Also, the water loss rate of the specimens and the transepidermal waterloss were analyzed for 10 kinds of lip make-up products (5 kinds of lipstick, 3 kinds of lip balm, 2 kinds of lip gloss). The moisture loss rate (moisture evaporation sensitivity) of the agar specimen was highest in the order of agar> Garaetteok> Japanese cake> wheat flour. Agar specimens are the most suitable in terms of spreadability, surface crack, and raw material supply. Containers for the preparation of agar specimens are suitable for plastic materials with low heat transfer, which can produce convex, smooth surface specimens. In the evaluation of moisturizing ability of lip makeup products, there was a strong correlation between the water loss rate and the transepidermal waterloss rate measured with agar specimens. These results show that the proposed method can be used as one of the useful alternative test methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.97-107
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• 2020

In this study, finite element analysis was carried out through the finite element analysis program (ANSYS) to investigate the fire resistance of composite columns in fire. Transient heat transfer analysis and static structural analysis were performed according to ASTM E 119 heating curve and axial force ratio 0.7, 0.6, 0.5 by applying stress-strain curves according to temperature, and loading heating experiments were carried out under the same conditions. In addition, the nominal compressive strength of the composite column according to the heating time according to the standard(Eurocode 4) was calculated and expressed as the axial force ratio and compared with the analytical and experimental values. Through the analysis, As a result of finite element analysis, the fire resistance time was 180 minutes and similar value to the experimental value was obtained, whereas the fire resistance time 150 minutes and 60 minutes were derived from the axial force ratios 0.6 and 0.7. In addition, it was confirmed that the fire resistance time according to the axial force ratio calculated according to the reference equation (Eurocode 4) was lower than the actual experimental value. However, it was confirmed that the standard(Eurocode 4) was higher than the experimental value at the axial force ratio of 0.7. Accordingly, it is possible to confirm the fire resistance characteristics(time-axial force ratio relationship) of the SRC column at high axial force, and to use the experimental and anaylsis data of the SRC column as the data for verification based on Eurocode.

• Solar Energy
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• v.14 no.2
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• pp.75-90
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• 1994

Thermal energy transport in a two-dimensional horizontal and vertical channel with an isothermal rectangular beam attached to one adiabatic wall is investigated from the numerical solution of Navier-Stokes and energy equations. The solutions have been obtained for dimensionless aspect equations. The solutions have been obtained for dimensionless aspect ratios of beam, H/B=$0.25{sim}4$, Reynolds numbers, Re=$50{\sim}500$ and Grashof numbers, Gr=$0{\sim}5{\times}10^4$. The mean Nusselt number, $\overline{Nu}$ for horizontal and vertical channels shows same value at Gr=0 and increases as Gr increases and decreases as H/B increases at Re=100. $\overline{Nu}$ of vertical channel shows higher in $0.25{\leq}H/B<1.1$ and lower in $1.1{\leq}H/B{\leq}4.0$ than that of horizontal channel at $Gr=10^4$, Re=100. $\overline{Nu}$ of vertical channel shows higher in $0.25{\leq}H/B<1.1$ and lower in $1.1{\leq}H/B=1.0$ than that of horizontal channel at Re=100, $0<Gr{\leq}5{\times}10^4$. A comparison between the experimental and numerical results shows good agreement.

• Elastomers and Composites
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• v.40 no.4
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• pp.266-271
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• 2005

In this work, the thermal stability factors, such as the thermal decomposition temperature, decomposition activation energy ($E_d$), and char yield, were measured to investigate the effect of silicone rubber (SR) content on the thermal stabilities of EPDM/SR blends. As a result, the thermal decomposition curve of EPDM/SR blends was similar to the neat EPDM rubber at 10 wt% SR and the thermal decomposition temperature increased above this content. The $E_d$ value of EPDM rubber initially decreased and then was constant above 20 wt% weight losses. The $E_d$ of EPDM/SR blends was higher than that of the neat EPDM rubber and then decreased with increasing the weight loss when the SR content was in the range of 10-20 wt%. Whereas the $E_d$ of the blends was lower than that of the EPDM rubber and then decreased with increasing the weight loss when 30 wt% SR was added. The char yield at $800^{\circ}C$ increased with increasing the SR content, because the decomposition of silane groups in the backbone was capable of forming a silane-rich residue after the initial stage of thermal degradation, which finally prevents further heat transfer and diffusion in the blends.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.1
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• pp.27-34
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• 2015

Many applications of nanoparticles have been developed since 1970s. Surface plasmon resonance (SPR) effect can be generated at the surface of nanoparticles by illumination. SPR is the resonant oscillation of conduction electrons at the surface material stimulated by incident light. The collisions between excited electrons and metal atoms can cause the production of thermal energy (photothermal effect). Here, we presented the development of thermo-cosmetics using photothermal effect of gold nanoparticles. Gold nanoparticles (GNPs) were chosen for it's low toxicity. We also and investigated the cell biocompatibility and heating effectiveness for photothermal effect of GNPs. Synthesized GNPs were verified by UV-vis spectrophotometer, where GNP has a characteristic absorbance spectrum. Concentration of GNP was measured by atomic absorption analyzer. The cytotoxicity was confirmed by MTT assay and double staining assay. Photothermal effect of GNP was demonstrated by the thermal increasing properties depending on GNP concentration, which was taken by an IR-thermal camera with a xenon lamp as the light source. If the thermal effect of GNP is applied for thermo-cosmetics, it can supply heat to skin by converting solar energy into thermal energy. Thus, cosmetics containing GNPs can provide benefits to people in the cold region or winter season for maintaining skin temperature, which lead to a positive effect on skin health.