• 소성∙가공
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• 제12권4호
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• pp.382-387
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• 2003

In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behaviors of the materials during indentation were studied with numerical method by ABAQUS S/W. Brittle materials (Si, Pyrex glass 7740) were used as specimens, and forming conditions to reduce the elastic recovery and pile-up were proposed. The indenter was modeled a rigid surface. Minimum mesh sizes of specimens are 1-10nm. Comparisons between the experimental data and numerical result demonstrated that the finite element approach is capable of reproducing the loading-unloading behavior of a nanoindentation test.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.337-337
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• 2004

As one of researches for the P ＆ T purposes, a basic experiment on the recovery of actinide elements from the mixture with rare earth elements by means of electrorefining using a liquid cadmium cathode in the LiCl-KC1 eutectic melt was carried out. In order to examine the behaviors of electrodeposition of metal ions on a liquid electrode, recovery experiments of rare earth metals resulting from forming electrodeposits were performed by a galvanostatic electrolysis method at various current densities. A cyclic voltammetric technique was applied to determine reduction-oxidation potential of each metal element in the melt and to detect the changes of the multi component melt composition for on-line monitoring. Also, a collaboration study with RIAR was completed to test the preliminary feasibility on a recovery of actinide elements from the mixture with rare earth elements using a liquid cadmium cathode and actinide metals. Experimental results showed that the ratio of actinides to rare earths, 9: 0.5∼1 led to the rare earth content of about 5∼10 wt% in the deposit.

• 열처리공학회지
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• 제4권3호
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• pp.1-6
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• 1991

In this study, intermediate thermo-mechanical treated Al-2.0 wt%Li, and Al-2.0 wt%Li-1.2 wt%Cu-1.0 wt%Mg-0.12 wt%Zr alloys were tested in tension at $10^{\circ}C$ and elevated temperature(100, 200 and $300^{\circ}C$). The results are follows : The tensile strength of Al-Li-Cu-Mg-Zr alloy is the highest but the elongation of Al-Li alloy is the highest(106%) among the all alloys in tension at $300^{\circ}C$. The Portervin-LeChartlier effect is showed in AI-Li-Cu-Mg-Zr alloy at 10 and $100^{\circ}C$, because of tangled dislocation by Mg and Cu. In the true stress-strain curves of all alloy, the peaks of stress at $300^{\circ}C$ are showed at the strain less than 0.1. In the binary alloy, the dynamic restoration process at 200 and $300^{\circ}C$ is nearly similar to dynamic recovery type. The hot deformation stress is decreased with increase of dynamic recovery degree, but the elongation is increased. When the strain the strain rate are constant, the temperature dependence of hot deformation stress is increased with increase of deformation temperature. The elongation and degree of dynamic recovery are decreased with increase of hot deformation activation energy, but the deformation stresses slightly increased.

• Smart Structures and Systems
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• 제24권2호
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• pp.157-171
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• 2019

This study investigated the effects of the geometric parameters of superelastic shape memory alloy (SE SMA) fibers on the pullout displacement recovering and self-healing capacity of reinforced cementitious composites. Three diameters of 0.5, 0.7 and 1.0 mm and two different crimped lengths of 5.0 and 10.0 mm were considered. To provide best anchoring action and high bond between fiber and cement mortar, the fibers were crimped at the end to create spear-head shape. The single fiber cement-based specimens were manufactured with the cement mortar of a compressive strength of 84 MPa with the square shape at the top and a dog-bone shape at the bottom. The embedded length of each fiber was 15 mm. The pullout test was performed with displacement control to obtain monotonic or hysteretic behaviors. The results showed that pullout displacements were recovered after fibers slipped and stuck in the specimen. The specimens with fiber of larger diameter showed better displacement recovering capacity. The flag-shaped behavior was observed for all specimens, and those with fiber of 1.0 mm diameter showed the clearest one. It was observed that the length of fiber anchorage did not have a significant effect on the displacement recovery, pullout resistance and self-healing capacity.

• 한국환경보건학회지
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• 제23권2호
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• pp.106-114
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• 1997

When surfactants meet chlorine bleaches not only in the washing drums but also through the whole path from the stream to the river, it is not difficult to expect that they produce the harmful substances like DBPs. Furthermore considering wastewater that is contaminated by surfactants is used to discharge into drinking water sources via sewer system, it also can be imagined that residual surfactants would contribute to the some extent of DBPs' formation during chlorine disinfection in water treatment plants. Although the main behavior observed was the formation of chloroform during the reaction of LAS with free chlorine, the other manifest behaviors like the trends of pH, MBAS, free chlorine, the mole concentration of benzene ring and etc. were also investigated.

• 한국해양공학회지
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• 제8권1호
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• pp.154-164
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• 1994

In this paper, fatigue testing was carried out under the change of aging time(0.5,1.5.10hrs) by electric heating method which is one of the useful method in the application of Robot's actuator. Fatigue degradation behaviors such as cyclic deformation property, amount of deformation, decrease in recovery and variation of transformation temperature for each specimen were examined closely, and the effect of aging time condition was studied on their fatigue degradation behaviors.

• 아동학회지
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• 제26권4호
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• pp.35-53
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• 2005

The attachment of Korean infants with their mothers was analyzed by individual attachment and interaction behaviors. The Strange Situation was used with 35 12- 18-month-old infants. Results were similar to the findings of Ainsworth et al(l978), in that exploratory and attachment behavior systems of Korean infants changed depending on separation with their mothers. Then again we could discover the orginal attachment characteristics of Korean infants. Korean infants showed meaningful differences in individual attachment and interaction behaviors from the second separation(episode 6), and the difference between attachnet type were also definite from the second separation. Also, the recovery of exploratory behavior from episode 7 with the advent of a stranger was a distinguishable characteristic compared to Ainsworth et al(l978). This empirical evidence mandates the inclusion of episodes 6 in future studies on attachment of Korean infants.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.478-485
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• 2002

The shape memory alloys (SMAs) are often used in smart materials and structures as the active components. Their ability to provide a high recovery force and a large displacement has been used in many applications. In this paper the radial displacement of an externally pressurized elliptic composite cylinder where SMA liner or strips actuators are bonded on its inner or outer surface is investigated numerically. The elliptic composite cylinders consisting of an inlet duct system with SMAs are designed and analyzed to determine the feasibility of such a system for the removal of stiffeners from an externally pressurized duct of an aircraft inlet. The deformations caused by prestrained SMAs placed on either surface of an elliptic composite cylinder are studied when activated. The externally pressurized elliptic composite cylinders with the SMA actuators were analyzed using the 3-D finite element method incorporated with 3-D SMA behaviors. The results show that the role of stiffeners may be switched by the activated light SMA actuators.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.24-32
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• 2018

Nanocellulose was surface-functionalized toward the applications in enhanced oil recovery (EOR) as a green alternative. The focus of this paper is on the effect of this material based nanofluid (NF) on foam lamella stabilization through studying its bubble breakup dynamics and flow behaviors in constricted mircofluidic devices. The NF stabilized foam produced an improved flow resistance across the capillary largely due to the capillary trapped bubbles at the contraction. The "snap-off" caused the NF stabilized foam to produce finer textured bubbles, which can migrate readily forward to the deep porous media, as revealed by the pressure profiles.

• 한국식품저장유통학회지
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• 제30권5호
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• pp.785-796
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• 2023

The aim of this study was to elucidate chemical structures and rheological properties of arabinogalactans (AGs) isolated from three legumes including black gram (BG), great northern bean (GNB), and California small white bean (CSWB). The ratio of galactose to arabinose (G/A) in three legumes increased in the order of BG > GNB > CSWB. The rheological measurements of 1-5% (w/v) AG solutions revealed Newtonian and non-Newtonian flow behaviors. BG exhibited yield stress, indicating plastic behavior. Small-amplitude oscillatory tests indicated viscoelastic properties of BG, GNB, and CSWB ranging from solid-like, paste-like, and liquid-like behaviors, respectively. Small-strain oscillatory tests were conducted to assess the structure recovery of the AGs after pre-shearing. G" values of BG and GNB increased, but those of CSWB remained constant after shearing. These results suggest that the chemical structures of the AGs, particularly their G/A ratios, influence their rheological properties.