• 대한기계학회논문집
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• 제18권2호
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• pp.424-431
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• 1994

The characteristics of supersonic flow with condensation along a wavy wall of a small Smplitude in a channel is investigated experimentally and numerically. In the present study for the case of supersonic moist air flow, the dependency of location of reflection of oblique shock wave generated by the wavy wall, and the distributions of flow properties in the flow field, on the stagnation relative humidity and temperature is clarified by the plots of streamline, iso-Mach number and iso-flow properties of numerical result and the schlieren photographs of experiment. And. experimental and numerical results are in good agreement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1372-1375
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• 2006

The simplified impedance model which can consider a combined flow condition was suggested. Although the strength and position of the shear layer cannot be obtained by a linear sum of two separate contributions when both flows occur together, it was simply assumed that the impedance under the combined flow follows from summing the separate flow impedance. To validate the simplified impedance model, acoustic properties of a concentric resonator was predicted and measured. The predicted transmission loss using the simplified model shows reasonable agreements with measurements. One can find that the simplified impedance model obtained by the superposition of the separate flow impedances can be adjusted to predict the acoustic properties of a concentric resonator.

• 대한기계학회논문집
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• 제19권9호
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• pp.2237-2248
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• 1995

In incompressible flow which has multi-length scale, it has a very important effect which dependent variables are used for adaptive grid generation. Among many length scales in incompressible flow, the dependent variables used for the adaptive grid generation should be able to represent the feature of the concerned system. In this paper, by using vorticity and stream function, in addition to velocity components, the smoother and more stable grid generation is possible and these four flow properties represent each scale. The adaptive grid generation for a lid-driven cavity flow with $N_{re}$ =3200 using four flow properties such as velocity components, vorticity, stream function is performed, and the usefulness of using vorticity and stream function as the indicator for adaptive grid generation is shown.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2010년도 춘계 학술논문 발표대회 2부
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• pp.67-68
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• 2010

Recently, there were not enough studies regarding the mix adjustment and changes of normal physical properties of slump flow type concrete in domestically. Therefore in this paper, it is aimed securing the fundamental data about flow its mix design method by experimental research. The experiment includes the adjustment of the way for slump flow type concrete by the variation of size of coarse aggregate. In the result, it is advisable raising the ratio of fine aggregate and unit water amount by considering the specific surface when increasing the Gmax size.

• 한국응용과학기술학회지
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• 제32권4호
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• pp.661-668
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• 2015

The surface rheological properties of polymer monolayer show complicated non-linear viscoelastic flow phenomena when they are subjected to spreading flow. These spreading flow properties are controlled by the characteristics of flow units. The kinetics of the formation of an interfacial film obtained after spreading poly(diisobutylene maleic acid) at air-water interface were studied by measuring of the surface pressure with time. The experimental data were analyzed theoretically according to a nonlinear surface viscoelastic model. The values of dynamic modulus, static modulus, surface viscosities and rheological parameters in various area/ monomer were obtained by appling experimental data to the equation of nonlinear surface viscoelastic model.

• 한국도로학회논문집
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• 제19권5호
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• pp.77-88
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• 2017

PURPOSES : It is necessary to clarify the rheological properties of cement paste as a basic research in the development of mechanistic concrete mix design. The rheological properties of cement paste with different binder types, mix propositions, and with/without high range water reducers have been analyzed. METHODS : In this study, ordinary Portland cement, fly-ash, blast furnace slag, silica fume, and limestone powder were used as binders. The range of water-binder ratio was 0.3-0.5, and a total of 30 different mixes have been tested. The slump flow test, V-funnel test, and Dynamic Shear Rheometer (DSR) test were performed to analyze the rheological properties of cement paste. RESULTS : As a result of the slump flow test, it was found that the composition ratio of the binder contents greatly affected the paste flow when the high range water reducers were added. The results of V-funnel test showed that when the water-binder ratio was decreased without high range water reducers, the binder composition ratio had a large effect on the passing time of the V-funnel tester, but with high range water reducers the impact of the binder composition ratio was decreased. The slump flow and V-funnel have a certain relationship with the rheological factors (yield stress and plastic viscosity), but the correlation was not significant. Finally, we proposed the M-value considering the density and specific surface area of the binder. The correlation between rheological factors and M-value were better demonstrated than experimental values, but there is still a limit to predict the rheological factor in general mix design. CONCLUSIONS :In this study, the rheological properties of cement paste were analyzed. The binder type, composition ratio of binder, and with/without high range water reducers have combined to provide the complex effects on the rheological properties of cement paste. The correlation between the proposed M-value and rheological factor was found to be better than experimental results, but needs to be improved in the future.

• 폴리머
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• 제24권1호
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• pp.38-47
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• 2000

본 논문은 선형 폴리카보네이트와 분지화된 폴리카보네이트를 블렌드한 시스템에 대해서 연구하였다. 여러가지 조성으로 두 성분을 블렌드하여 각 조성에 대해서 상용성, 기계적 성질 그리고 유동특성을 조사하였다. 본 블렌드 시스템에서 상분리는 관찰되지 않았고 상용성도 있었다. 기계적 성질은 블렌드의 각 조성에 대해서 인장강도, 굽힘강도 그리고 충격강도 등을 측정하여 검토하였으며, 흐름특성 역시 블렌드의 각 조성에 대해 용융점도, 저장탄성률 및 손실탄성률을 여러 온도에서 측정하여 검토하였다. 그리고 용융점도의 분자량에 대한 의존성을 조사하였다. 선형 폴리카보네이트와 분지화된 폴리카보네이트의 조성에 따라 기계적 물성은 거의 변화가 없었으나, 흐름특성은 큰 변화가 있었다. 본 블렌드 시스템에서 분지화된 폴리카보네이트 함량이 증가할수록 점도의 분자량에 대한 의존성이 컸으며, shear thinning 현상은 두드러지게 나타났다. 따라서 재료의 기계적 물성의 변화없이 흐름특성이 다른 블렌드 시스템을 설계할 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.596-599
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• 2004

The purpose of this study is to investigate properties of porous concrete according to rheological properties of binder and compaction factor. The results of this study, the rheological property of binder is stabilized when a mixing time is over 240 seconds in case of target flow values are $175\%\;and\;200\%$. The void ratio of specimen has a very near value by target void ratio on the whole according as the rheological properties of binder and compaction energy are changed when target flow value is $200\%$, compaction energy is $75kN{\cdot}m/m^2$. The specimen has the excellent compressive strength when compaction energy and target flow value are $100kN{\cdot}m/m^2$ and $200\%$ respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.602-605
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• 2007

Soybean and rape seed are common feedstocks for biodiesel product ion in USA and Europe, respectively. On the other hand, South Eastern countries like Malaysia and Indonesia have surplus palm crops. However due to substantial amount of saturated fats in palm, the palm biodiesel has poor low temperature properties. To improve the low temperature flow properties as biodiesel, the dependence of the cold filter plugging point (CFPP) on the fatty acid compositions was examined. Two different kinds of biodiesels, palm and soybean biodiesels, were blended with the different volume ratios. And the low temperature flow properties of 0.5%, 1%, and 5% biodiesel in diesel blend fuels was tested. The decrease of CFPP was not observed for BD1 with Palm BD. Also, WDI test didn't exceed in the range of 4oC by the mixing of Palm BD upto 5% in commercial diesels.

• International Journal of Concrete Structures and Materials
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• 제6권1호
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• pp.59-64
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• 2012

Sand-concrete is being researched for potential usage in construction in Saharan regions of Algeria, because of shortage in coarse aggregate resources. This research work deals with the effect of dune sand, available in huge quantities in these regions, on the properties of flowing sand-concrete (FSC) prepared with different proportions of dune and river sands. Mini-cone slump test, v-funnel flow-time test and viscosity measurements were used to characterize the behaviour of FSC in fresh state. The 28-day compressive strength was also determined. Test results show that an optimal content of dune sand, which makes satisfied fresh and hardened properties of FSC, is obtained. Moreover, the obtained flow index (constant b) calculated by the help of power-law viscosity model is successfully correlated to the experimental results of v-funnel flow time.