• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.7-11
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• 2000

In this paper was studied on the mechanical characteristics of Glass Fiber Reinforced Plastics(GFRP) of the steel bar it is to replace. The advantage of FRP such as high strength, low weight and chemical inertness or noncorrosiveness can be fully exploited. GFRP bar were successfully fabricated at l0mm nominal diameters of solid and hollow types using a pultrusion method. Tensile and bending specimens from this bar were tested and compared with behavior of GFRP rebar and steel bar.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.199-205
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• 2001

This paper describes the design methodology, manufacturing process, rebar tensile and bending properties. Braidtrusion is a direct Composite fabrication technique utilizing an in-line braiding and pultrusion process. The produced Composite rebar exhibits ductile stress-strain behavior similar to that of conventional steel bar. Various rebar diameters ranging from modeling scale(3m) to full-scale prototype of 9.5mm have been produced Glass Fiber Reinforced Plastics(GFRP) rebar were successfully fabricated at $\phi$8.5mm and $\phi$9.5mm nominal diameters of soild and hollow type using a braidtrusion process. Tensile and bending specimens were tested and compared with behavior of stress-strain of GFRP rebar and steel bar.

• Journal of Korea Foundry Society
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• v.33 no.4
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• pp.157-161
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• 2013

A ribbon-type polycrystalline silicon wafer was directly fabricated from liquid silicon via a novel technique for both a fast growth rate and large grain size by exploiting gas pressure. Effects of processing parameters such as moving speed of a dummy bar and the length of the solidification zone on continuous casting of the silicon wafer were investigated. Silicon melt extruded from the growth region in the case of a solidification zone with a length of 1cm due to incomplete solidification. In case of a solidification zone wieh a length of 2 cm, on the other hand, continuous casting of the wafer was impossible due to the volume expansion of silicon derived from the liquid-solid transformation in solidification zone. Consequently, the optimal length of the solidification zone was 1.5 cm for maintaining the position of the solid-liquid interface in the solidification zone. The silicon wafer could be continuously casted when the moving speed of the dummy bar was 6 cm/min, but liquid silicon extruded from the growth region without solidification when the moving speed of the dummy bar was ${\geq}$ 9 cm/min. This was due to a shift of the position of the solid-liquid interface from the solidification zone to the moving area. The present study reports experimental findings on a new direct growth system for obtaining silicon wafers with both high quality and productivity, as a candidate for an alternate route for the fabrication of ribbon-type silicon wafers.

• Membrane and Water Treatment
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• v.6 no.2
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• pp.113-126
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• 2015

Salinity gradient power (SGP) systems have strong potential to generate sustainable clean electricity for 24 hours. Here, we introduce a solid-salt pressure-retarded osmosis (PRO) system using crystal salt powders rather than seawater. Solid salts have advantages such as a small storage volume, controllable solubility, high Gibbs dissolution energy, and a single type of water intake, low pretreatment costs. The power densities with 3 M draw solutions were $11W/m^2$ with exothermic energy and $8.9W/m^2$ without at 35 bar using a HTI FO membrane (water permeability $A=0.375L\;m^{-2}h^{-1}bar^{-1}$). These empirical power densities are ~13% of the theoretical value.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1084-1088
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• 1995

A complete solid solution (SrLaAl1-xNixO4) between insulating SrLaAlO4 and metallic SrLaNi(Ⅲ)O4 oxides were prepared under high oxygen pressure (1.5 kbar, 800 ℃). They have tetragonal K2NiF4-type structure in all the solid solution range. Compared with lattice parameters of the same solid solution prepared under normal condition (1 bar, 1200 ℃), large decrease in the c-parameter was induced by high pressure treatment while no noticeable variation of the a-parameter was observed. Although marked changes of structural parameters, magnetic susceptibilities, and electron paramagnetic resonance spectra were consistently occurred before and after x=0.5, overall behaviors were essentially the same with those of solid solution prepared under normal condition. Such a phenomenon is explained by assuming the formation of partially filled narrow σ*x2-y2 band for x>0.5. Lattice contraction along the c-axis by high pressure treatment seems not to broaden this band. Particularly, the continuous absorption characteristic of a high free carrier concentration for x>0.5 and the absence of Ni-O in-plane stretching mode in the infrared absorption spectra supports this picture. However, the conductivities increasing with temperature for all solid solution suggest that some localization character, of probably Anderson type, remains for x>0.5.

• Steel and Composite Structures
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• v.18 no.4
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• pp.853-871
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• 2015

Up to now, Japan has more than 200 corrugated steel web composite beam bridges which are under construction and have been constructed, and China has more than 30 corrugated steel web composite beam bridges. The bridge type includes the simply supported beam, continuous beam, continuous rigid frame and cable stayed bridge etc. The section form has developed to the single box and multi-cell box girder from the original single box and single chamber. From the stress performance and cost saving, the span range of 50~150 m is the most competitive. At present, the design mostly adopts the computational analytical method combining the spatial bar system model, plane beam grillage model and solid model. However, the spatial bar system model is short of the refinement analysis on the space effect, such as the shear lag effect, effective distribution width problem, and eccentric load factor problem etc. Due to the similarity of the plane beam grillage method in the equivalence principle, it cannot accurately reflect the shearing stress distribution and local stress of the top and bottom plates of the box type composite beam. The solid model is very difficult to combine with the overall calculation. Moreover, the spatial grid model can achieve the refinement analysis, with the integrity of the analysis and the comprehensiveness of the stress checking calculation, and can make up the deficiency of the analytical method currently. Through the example verification of the solid model and spatial grid model, it can be seen that the calculation results for the stress and the displacement of two models are almost consistent, indicating the applicability and precision of the spatial grid model.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.712-715
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• 2009

본 연구에서는 고밀도, 고촉진 가스하이드레이트 생성 촉진제 (promoter)의 개발을 위하여 음이온성 멀티체인형 게면활성제를 제조하였다. 또한 각 계면활성제의 알킬그룹의 길이에 따라 같은 조건에서의 계면활성제의 촉진 효과를 비교하였다. $1^{\circ}C$에서 35bar,40bar로 압력을 달리하여 비교 실험하여 메탄 하이드레이트 생성속도를 측정하고, 각 조건에서의 계면활성제의 촉진 효과를 비교하였다. 알킬그룹의 길이가 짧을수록, 압력이 높을수록 촉진 속도가 빠르다. 또한 기존의 상용화된 SDS(Sodium dodecyl sulfate)보다 본 연구에서 제조한 C10의 음이온성 멀티체인형 계면활성제가 SDS 대비하여 소량으로도 충분한 효과를 나타냄을 확인하였다.

• Environmental Engineering Research
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• v.25 no.2
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• pp.251-257
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• 2020

This study was performed to verify the possibility of nitrification and denitrification in a single reactor. In batch type experiment, optimal point of experimental conditions could be found by performing the experiments. When supply location of microbubbles was located at half of width of the aeration tank and operating pressure of 0.5 bar, it was possible for zones in the aeration tank to be separated into anoxic and aerobic by controlling air suction rate according to operating pressure of the generator. To be specific, the concentration of dissolved oxygen (DO) in zone 1 and 2 of the aeration tank could be maintained as less than 0.5 mg/L. Also, in the case of concentration of oxygen in zone 3 and 4, the concentration of DO was increased up to 1.7 mg/L due to effects of microbubbles. In continuous flow type experiment based on the results of batch type experiments, the removal efficiency of nitrogen based on T-N was observed as 39.83% at operating pressure of 0.5 bar and 46.51% at operating pressure of 1 bar so it was able to know that sufficient air suction rate should be required for nitrification. Also, denitrification process could be achieved in a single reactor by using ejector type microbubble generator and organic matter and suspended solid could be removed. Therefore, it was possible to verify that zones could be separated into anoxic and aerobic and nitrification and denitrification process could be performed in a single reactor.

• Bulletin of the Korean Chemical Society
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• v.17 no.5
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• pp.443-447
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• 1996

Several polysilanes with sterically bulky substituents such as poly(2-phenylpropyl)(n-hexyl)silane were prepared by Wurtz-type coupling. The polysilane products were mixtures of low-molecular-weight polymers (&bar{M};w~103) as major and high-molecular-weight polymers (&bar{M};w~106) as minor. Overall yields for polysilanes were in the range of 81-99%. λmax of liquid low MW polymers appeared at around 280 nm. Formations of solid high MW polymers were decreased by a longer reaction time and increased steric bulkiness of substituents. High MW polymers with λmax at 327 nm except crosslinked polymers were soluble in common organic solvents and found to be light sensitive. Crosslinked high MW polymer gave 21% TGA ceramic yield, compared with linear high polymer giving zero ceramic yield.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.41-51
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• 2018

In case of evaluating the bond stress of a void deck plate using a wire steel, there is no standard formula considering both the influence on the void and the type of the reinforcing bar. Therefore we proposed a model equation considered the bond characteristics of the void deck plate. A total of 46 specimens was carried out a direct pull-out test and the test variables were the presence of a void body, type of reinforcing bar, the inner cover thickness according to the location of reinforcing bars and bond region. As a result of the comparison between the steel bar and steel wire, the bond stress of the steel wire with the relative rib area of 0.071 is 4.5 ~ 28.58% lower than that of the steel bar with 0.092 and the bond stress reduction rate increases when the inner cover thickness is insufficient. In the case of the inner cover thickness of $1.7d_b$ and $2.7d_b$, the bond stress was reduced to 48.7 ~ 68.4%. In the inner cover thickness was $4.9d_b$ and $5.2d_b$, the bond stresses were equivalent to those of the solid specimens. It was confirmed that the average bond stress and strain were affected by the inner cover thickness. Therefore the predicted model for one module of the void deck plate is proposed and verified by considering the bond characteristics of the void deck plate.