• 주류산업
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• v.26 no.1 s.87
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• pp.40-47
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• 2005

• 주류산업
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• v.28 no.2 s.96
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• pp.28-33
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• 2008

• 월간낙농육우
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• v.23 no.12 s.260
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• pp.94-101
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• 2003

• 월간낙농육우
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• v.23 no.3 s.251
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• pp.146-149
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• 2003

• Monthly Duck's Village
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• s.85
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• pp.52-55
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• 2010

• Tunnel and Underground Space
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• v.13 no.4
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• pp.304-315
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• 2003

In this paper, the DDA method with a new hydro-mechanical algorithm is used to study the effect of rock discontinuities on uplift and seepage in concrete gravity dam foundations. This paper presents an alternative method of predicting uplift and seepage at the base of concrete gravity dams. A sensitivity analysis was carried out to study the importance of several parameters on dam stability such as the orientation, spacing, and location of discontinuities. The study shows that joint water flow and adverse geological conditions could result in unusual uplift at the base of concrete gravity dams, well in excess of what is predicted with the classical linear or hi-linear pressure assumption. It is shown that, in general, the DDA program with the hydro-mechanical algorithm can be used as a practical tool in the design of gravity dams built on fractured rock masses.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.3
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• pp.1-7
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• 2014

This paper describes the implementation of high speed comparator for the ATE (automatic test equipment) system. The comparator block is composed of continuous comparator, differential difference amplifier(DDA) and output stage. For the wide input dynamic range of 0V to 5V, and for the high speed operation (1~800MHz), high speed rail-to-rail amplifier is used in the first stage. And hysteresis circuits, pre-amp and latch are followed for high speed operation. To measure the difference of output signals between the two devices under test (DUTs), a DDA is applied because it can detect the differences of both common signals and differential signals. This comparator chip was implemented with $0.18{\mu}m$ BCDMOS process and can compare the signal difference of 5mV up to the frequency range of 800 MHz. The chip area of the comparator is $620{\mu}m{\times}830{\mu}m$.

• Polymer(Korea)
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• v.33 no.4
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• pp.333-341
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• 2009

Polypropylene (PP)/functionalized multiwalled carbon nanotube (F-MWNT) nanocomposites were prepared by using solution intercalation method with different F-MWNT loads. The PP composite films, which contain dodecanol-MWNT (DDO-MWNT) or dodecylamine-MWNT (DDA-MWNT) as reinforcing additive, were evaluated by thermomechanical properties, morphology, electrical conductivity and gas permeability. The images from electron microscopy (SEM and TEM) showed that F-MWNTs were homogeneously dispersed in PP matrix, while they were agglomerated in some other part. The addition of F-MWNT could improve thermomechanical properties of the films. The maximum enhancement was observed at 2 wt% F-MWNT. DDO-MWNT was more effective than DDA-MWNT for both tensile modulus and optical transparency of the films.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.1075-1084
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• 2005

The compressive strength of concrete is commonly used criterion in producing concrete. However, the tests on the compressive strength are complicated and time-consuming. More importantly, it is too late to make improvement even if the test result does not satisfy the required strength, since the test is usually performed at the 28th day after the placement of concrete at the construction site. Therefore, accurate and realistic strength estimation before the placement of concrete is being highly required. In this study, the estimation of the compressive strength of concrete was performed by probabilistic neural network(PNN) on the basis of concrete mix proportions. The estimation performance of PNN was improved by considering the correlation between input data and targeted output value. Improved probabilistic neural network was proposed to automatically calculate the smoothing parameter in the conventional PNN by using the scheme of dynamic decay adjustment (DDA) algorithm. The conventional PNN and the PNN with DDA algorithm(IPNN) were applied to predict the compressive strength of concrete using actual test data of two concrete companies. IPNN showed better results than the conventional PNN in predicting the compressive strength of concrete.

• Elastomers and Composites
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• v.54 no.4
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• pp.335-344
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• 2019

In this work, styrene butadiene rubber (SBR) and styrene butadiene styrene (SBS) were used to modify asphalt, resulting in SBR- and SBS-modified asphalt, respectively. The two modified asphalts were emulsified with a nonionic emulsifier (Span 60) and cationic emulsifiers (ID, DDA) and their phase stabilization was investigated via particle size, Zeta potential, and flow behavior analysis. With increasing amount of the mixed emulsifier, the particle size decreased, leading to an increase in viscosity. The shear thinning behaviors and Zeta potential values ranging from 35-65 mV were determined and remained considerably stable. In addition, the adhesion strength and compression strength of the SBR-and SBS-modified asphalt emulsion were evaluated via surface free energy examination. The remarkable adhesion and compression strengths were estimated when 5 phr ID and 6 phr DDA were added to the emulsified asphalt modified with SBR and SBS. Therefore ID and DDA, the two cationic surfactants, played significant roles in improving the dispersion and interfacial adhesion strength, resulting in the improved adhesion and compression strength of the emulsified asphalts modified with SBR and SBS.