• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.6
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• pp.258-263
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• 2008

The fine aggregates of below 2 mm size was fabricated using by the vertical furnace in which the aggregates could be sintered at floating state and its physical properties were analyzed. The liquid formed at the surface of specimens sintered at $1200{\sim}l300^{\circ}C$ induced a gas in core to expand so the denser shell and porous core could be produced. The C series specimen fabricated by crushing an extruded body had an irregular shape and sharp edges but those became spheroidized by bloating due to gas expansion inside. The fine aggregates fabricated in this study was as light as floating in the water and had an apparent density of $0.68{\sim}1.08$. The absorption rate was proportioned to a porosity showing that the pores in core was not closed completely. The properties of fine aggregates fabricated in vertical furnace were similar with those of in an electric muffle furnace but the sticking-together phenomenon by surface fusion was not occurred in the vertical furnace. The aggregates fabricated in this study had a little lower impact resistance than that of natural aggregate but satisfied the unit volume weight standard specified in KS.

• Journal of the Korean Geosynthetics Society
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• v.11 no.3
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• pp.27-35
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• 2012

In this paper, the frost heaving and thawing characteristics of flexible pavement structure were evaluated in the large scale freezer which have a specification of temperature range $-20^{\circ}C{\sim}10^{\circ}C$ and $3.2m(L){\times}3.2m(B){\times}2.4m(H)$ in size. The insulated steel box with the size of $0.9m(L){\times}0.9m(B){\times}0.9m(H)$ was used to simulate actual pavement road structure. The variation of temperature, frost heave amount and frost heave pressure were measured through the instrument of TDS-602 data logger. LFWD (light falling weight deflectometer) was used to determine the change of deflection due to the frost heaving and thawing. Furthermore, the influence of aggregate layer to the freezing of the subgrade soil was studied to verify the function and effectiveness of the anti-freezing layer.

• Journal of Ocean Engineering and Technology
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• v.19 no.4 s.65
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• pp.28-34
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• 2005

In the study application of volcanic scoria concrete to artificial reefs is investigated. Volcanic scoria is a natural volcanic product that shows light weight, mil/i-porous, and far-infrared irradiation characteristics. The properties of volcanic scoria concrete using Jeju scoria aggregate are evaluated by conducting a comprehensive series of tests on strength and void ratio. It is concluded that the volcanic scoria concrete has the sufficient strength of 4MPa-13MPa and adequate void ratio of $12\%-35\%$ to be accepted as artificial reef concrete. The field experiments are performed through observation by scuba diver's at the Seogwipo coast. Porous specimen and plane concrete specimen are prepared for comparison purposes. Seasonal changes of soft coral on the two series of test specimens were have been observed from Apr. 9, 2004 to Mar. 18, 2005. The soft coral is well grown on the porous specimen however there are no significant changes on the conventional plain concrete specimen. Thus it is concluded that the volcanic scoria concrete is highly suitable as artificial reef concrete.

• Textile Coloration and Finishing
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• v.30 no.3
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• pp.190-198
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• 2018

We fabricated high transmission and high scattering poly(ethylene-co-vinyl acetate)(EVA) films embedding $SiO_2$ nanoparticles to improve outcoupling efficiency in organic display. The 800nm diameter $SiO_2$ nanoparticles aggregated and formed $1.56{\mu}m$ (with ${\pm}0.853{\mu}m$ standard deviation) diameter microparticles in EVA. The total transmission of scattering film was 83.3% on Polyethylene terephthalate(PET), which was higher than reference 82.8% PET substrate. The diffuse transmission and haze of the $SiO_2$ embedded EVA film were 76.1% and 91.4%, respectively. The optimized condition was 1:1 weight ratio of $SiO_2$ nanoparticles to EVA in Tetrahydrofuran(THF) solution. When the ratio of $SiO_2$ was larger than 1, the total transmission decreased by the increase in backscattering of light due to high scattering. With the optimized condition, we could succeed to fabricate a large scale film(35m in length) with a roll-to-roll process.

• Steel and Composite Structures
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• v.7 no.6
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• pp.457-468
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• 2007

Analytical and experimental investigation on dynamic properties of extra lightweight concrete sandwich beams reinforced with various lay ups of carbon reinforced epoxy polymer composites (CFRP) are discussed. The lightweight concrete used in the core of the sandwich beams was made up of extra lightweight aggregate, Lica. The density of concrete was half of that of the ordinary concrete and its compressive strength was about $100Kg/cm^2$. Two extra lightweight unreinforced (control) beams and six extra lightweight sandwich beams with various lay ups of CFRP were clamped in one end and tested under an impact load. The dimension of the beams without considering any reinforcement was 20 cm ${\times}$ 10 cm ${\times}$ 1.4 m. These were selected to ensure that the effect of shear during the bending test would be minimized. Three other beams, made up of ordinary concrete reinforced with steel bars, were tested in the same conditions. For measuring the damping capacity of sandwich beams three methods, Logarithmic Decrement Analysis (LDA), Hilbert Transform Analysis (HTA) and Moving Block Analysis (MBA) were applied. The first two methods are in time domain and the last one is in frequency domain. A comparison between the damping capacity of the beams obtained from all three methods, shows that the damping capacity of the extra lightweight concrete decreases by adding the composite reinforced layers to the upper and lower sides of the beams, and becomes most similar to the damping of the ordinary beams. Also the results show that the stiffness of the extra lightweight concrete beams increases by adding the composite reinforced layer to their both sides and become similar to the ordinary beams.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.2
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• pp.155-161
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• 2005

The inherent instability of metabolite production in plant cell culture-based bioprocessing is a major problem hindering its commercialization. To understand the extent and causes of this instability, this study was aimed at understanding the variability of anthocyanin accumulation during long-term subcultures, as well as within subculture batches, in Vitis vinifera cell cultures. Therefore, four cell line suspensions of Vitis vinifera L. var. Gamay Freaux, A, B, C and D, originated from the same callus by cell-aggregate cloning, were established with starting anthocyanin contents of $2.73\;\pm\;0.15,\;1.45\;\pm\;0.04,\;0.7\;\pm\;0.024\;and\;0.27\;\pm\;0.04$CV (Color Value)/g-FCW (fresh cell weight), respectively. During weekly subculturing of 33 batches over 8 months, the anthocyanin biosynthetic capacity was gradually lost at various rates, for all four cell lines, regardless of the significant difference in the starting anthocyanin content. Contrary to this general trend, a significant fluctuation in the anthocyanin content was observed, but with an irregular cyclic pattern. The variabilities in the anthocyanin content between the subcultures for the 33 batches, as represented by the variation coefficient (VC), were 58, 57, 54, and $84\%$ for V. vinifera cell lines A, B, C and D, respectively. Within one subculture, the VCs from 12 replicate flasks for each of 12 independent subcultures were averaged, and found to be $9.7\%$, ranging from 4 to $17\%$. High- and low-producing cell lines, VV05 and VV06, with 1.8-fold differences in their basal anthocyanin contents, exhibited different inducibilities to L-phenylalanine feeding, methyl jasmonate and light irradiation. The low-producing cell line showed greater potential in enhanced the anthocyanin production.

• Steel and Composite Structures
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• v.50 no.6
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• pp.675-688
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• 2024

Cold-formed steel (CFS) is prone to buckling failure under loading. Lightweight concrete (LC) made of lightweight aggregate has light weight and excellent thermal insulation performance. However, concrete is brittle in nature which is why different materials have been used to improve this inherent behavior of concrete. The distortional buckling (DB) performance of cold-formed steel-lightweight concrete (CFS-LC) composite columns was investigated in this paper. Firstly, the compressive strength test of foam concrete (FC) and ceramsite concrete (CC) was carried out. The performance of the CFS-LC members was investigated. The test results indicated that the concrete-filled can effectively control the DB of the members. Secondly, finite element (FE) models of each test specimen were developed and validated with the experimental tests followed by extensive parametric studies using numerical analysis based on the validated FE models. The results show that the thickness of the steel and the strength of the concrete-filled were the main factors on the DB and bearing capacity of the members. Finally, the bearing capacity of the test specimens was calculated by using current codes. The results showed that the design results of the AIJ-1997 specification were closer to the experimental and FE values, while other results of specifications were conservative.