• Advances in concrete construction
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• 제5권4호
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• pp.377-390
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• 2017

This study proposes a mix design method for geopolymer concrete (GPC) using low calcium fly ash and alccofine, with the focus on achieving the required compressive strength and workability at heat and ambient curing. Key factors identified and nine mixes with varied fly ash content (350, 375 and $400kg/m^3$) and different molarity (8, 12 and 16M) of NaOH solutions were prepared. The cubes prepared were cured at different temperatures ($27^{\circ}C$, $60^{\circ}C$ and $90^{\circ}C$) and tested for its compressive strength after 3, 7 and 28 days of curing. Fly ash content has been considered as the direct measure of workability and strength. The suggested mix design approach has been verified with the help of the example and targets well the requirements of fresh and hardened concrete.

• 한국세라믹학회지
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• 제32권2호
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• pp.155-162
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• 1995

Solid oxide electrolytes of the MCe1-xGdxO3-x/2 (M: Ba, Mg. x=0.0-0.20) system were prepared using powders synthesized by the "liquid mix" method and calcined from the cross-linked polyacrylic polymer. The specimens were analyzed using XRD and SEM with EDX, and the sintering behavior of the electrolytes and their electrical conductivity were also studied. Although Mg-cerate is relatively inferior to Ba-cerate in the sinterability and chemical homogenity(EDX analysis data), both the Ba- and the Mg-cerate electrolytes at 80$0^{\circ}C$ show their maximum conductivities at x=0.10 and their values are in the same order of magnitude, i.e., 3.5$\pm$0.17.10-2(ohm.cm)-1.ohm.cm)-1.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.269-272
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• 2005

Due to the high density and heating value, liquid fuel is attractive for ramjet propulsion system. Liquid fuel requires time to evaporation and mix with incoming air before ignition; insufficient evaporation and mixing result in low combustion efficiency and instability. So the numerical studies are conducted to investigate the spray and combustion characteristics of a liquid-fueled dump type Integrated Rocket Ramjet combustor. The governing equations are solved by means of a finite-volume using time derivative preconditioning method for chemical reacting flow. The liquid phase is treated by solving Lagrangian equations of motion and transport for the life histories of a statistically significant sample of individual droplets.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.218-222
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• 2006

Due to the high density and heating value, liquid fuel is attractive for ramjet propulsion system. Liquid fuel requires time to evaporation and mix with incoming air before ignition; insufficient evaporation and mixing result in low combustion efficiency and instability. So the numerical studies are conducted to investigate the spray and combustion characteristics of a liquid-fueled dump type Ramjet combustor. The governing equations are solved by means of a finite-volume using time derivative preconditioning method for chemical reacting flow. The liquid phase is treated by solving Lagrangian equations of motion and transport for the life histories of a statistically significant sample of individual droplets.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1162-1167
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• 2004

From the early 1980's, the New Austrian Tunnelling Method (NATM) has been developed as a one of the standard tunneling method in Korea. Owing to the results of many researches, the practical problems of shotcrete has been improved for a last decade. However, the excess amount of rebound still remains one of the critical problems in shotcrete technology. In order to improve for this rebound problem, recently developed cement mineral accelerator has been successfully applied to several NATM tunnels in Korea. An experimental investigation was carried out in order to verify the rebound characteristics of wet-mix Steel Fiber Reinforced Shotcrete (SFRS) with powder types cement mineral accelerator. Mortar setting test, SEM analysis, bonding test under spring water condition and rebound test were conducted. From the result, wet-mix SFRS with cement mineral acelerator exhibited excellent bonding characteristics even spring water condition and less rebound ratio compared to the conventional liquid accelerator.

• 생약학회지
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• 제49권4호
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• pp.349-361
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• 2018

Socheongryong-tang (SCRT) was one of the major traditional herbal medicines wildly used in the treatment of respiratory disease. SCRT is being commercially produced in the form of mix extracts powder and soft dry extract by different extract methods in the Korean Herbal Pharmacopeia (KHP). In this study, the contents of marker components and biological activities of the SCRT mix extract powder were compared with those of the SCRT decoction. To analyze the marker components of SCRT, nine marker from eight herbal preparations were chosen. And the method using high performance liquid chromatography (HPLC) with diode-array detector method was established for the simultaneous analysis. Method validation was accomplished by linearity, precision test, and recovery test. The contents of nine marker components in this extract was ascertained by ratio. The biological activities were examined the effect of SCRT on anti-oxidation and pro-inflammation mediated by LPS-stimulation. We confirmed that both of SCRT mix extrct powder and decoction have the similar contents on total polyphenol and flavonoid and inhibited the secretion of nitric oxide (NO), $IL-1{\beta}$, IL-6, tumor necrosis factor $(TNF)-{\alpha}$ and the expression of iNOS, COX-2, $IL-1{\beta}$, IL-6, $TNF-{\alpha}$. These results suggest that SCRT mix extract powder and decoction have a significant correlation.

• 대한안전경영과학회지
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• 제13권2호
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• pp.275-282
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• 2011

A core device of foam system is the in-line eductor and it is the device to mix the foam liquid into liquid solution proper to the use density and the mixture ratio must be kept regularly regardless of changing fluid condition of the front and rear end of the in-line eductor. However, if the flux of the pressurized water changes, the mixture ratio is not kept regularly, and so it becomes a cause which a performance of fire-extinguishing deteriorates in discharging foam liquid. I devise a method to improve it that the metering orifice type in-line eductor is improved into the metering venturi type in-line eductor, the fluctuation of the mixture ratio to the flux change of the pressurized water is minimized and the performance of fire-extinguishing is kept regularly. As this method is simple in its structure and can be designed at a low cost, it helps for maintenance as well. In the future, it seems to need the research for the metering nozzle type in-line eductor in the future.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.163-166
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• 2006

This paper presents numerical results of fluid flows and mixing in a microfluidic device for AC electroosmotic flow (AC-EOF) with coplanar electrodes on top and bottom walls. Differently from previous EOF a channel which attached a couple of coplanar electrodes can be utilized to mix a target liquid with a reagent. In this study we propose a method of controlling fluid flows and mixing enhancement. To obtain the flow and mixing characteristics, numerical computations are performed by using a commercial code, CFX10. It was found that the flow near the coplanar electrodes is of 3-D complex flows and vortices between the other electrodes, and as a consequence the AC-electroosmotic flow on the electrodes plays an important role in mixing the liquid.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.695-702
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• 2002

Shotcrete (or Sprayed concrete) has been used as an important support material in New Austrian Tunnelling Method (NATM). Since the mid of 1990, permanent shotcrete tunnel linings such as Single-shell, NMT (Norwegian Method of Tunnelling) has been constructed in many countries for reducing the construction time and lowing construction costs instead of conventional in-situ concrete linings. Among essential technologies for successful application of permanent shotcrcte linings, high performance shotcrete providing high strength, high durability, better pumpability has to be developed in advance as an integral component. This paper presents the Ideas and first experimental attempts to increase early strength and bond strength of wet-mixed Steel Fiber Reinforced Shotcrete(SFRS) in sump water condition. In order to increase early strength, a new approach using high-early strength cement with liquid alkali-free accelerator has been investigated From the results, wet-mix SFRS with high-early strength cement and alkali-free accelerator exhibited excellent early strength improvement compared to the ordinary portland content and good bond strength even under sump water condition.

• 한국전산유체공학회지
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• 제11권3호
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• pp.46-51
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• 2006

This paper presents the numerical results of fluid flow and mixing in a microfluidic device for electro-osmotic flow (EOF) with an trapezoidal electrode array on the bottom wall (ETZEA). Differently from previous EOF in a channel which only transports fluid in colloidal system. ETZEA can also be utilized to mix a target liquid with a reagent. In this study we propose a method of controlling fluid flow and mixing enhancement. To obtain the flow and mixing characteristics, numerical computations are performed by using a commercial code, CFX-10, and a self-made code LBM-D. It was found that the flow near the trapezoidal electrode in the ETZEA is of 3-D complex flows due to the zeta potential difference between the trapezoidal electrode and channel walls, and as a consequence the hetrogeneous zeta potential on the electrodes plays an important role in mixing the liquid.