• Journal of Korea Foundry Society
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• v.22 no.5
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• pp.245-251
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• 2002

Cast AZ91 and extruded AM50 alloys were isothermally heated as solid/liquid coexistent temperatures, and semi-solid formed into sheets. Mold filling ability of semi-solid slurry with different liquid fractions was investigated in relation to process variables such as injection speed and mold temperature. Relatively uniform distribution of solid particle size and liquid fraction were observed throughout the semi-solid formed sheet. AZ91 alloy sheets were also manufactured by conventional die casting and compared with the semi-solid formed. It was found that the surface was more smooth and the dimensional accuracy was higher in case of the semi-solid formed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.2
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• pp.124-131
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• 1993

Recently. with the rapid development in large sea water systems. there occurs much interest in the study of erosion-corrosion. In this study. the mild steel(SB41) was tested by using of a erosion-corrosion test apparatus with fountain-jet and was investigated under the environments of liquid, air-liquid 2 phase flow and solid particle-liquid 2 phase flow. Main results obtained are as follows : 1. The weight loss by corrosion-erosion in air-liquid 2 phase flow are more increased than that in only liquid solution. 2. Effect of air-liquid 2 phase flow on corrosion-erosion sensitivity becomes more sensitive in natural seawater than that in distilled water. 3. The corrosion potential by corrosion-erosion in air-liquid and solid particle-liquid 2 phase flow becomes noble than that of only liquid solution.

• Journal of Information Display
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• v.10 no.2
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• pp.76-79
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• 2009

In Joule-heating-induced crystallization, solid-to-solid or liquid-to-solid phase transformation could occur. It was found that novel physical phenomena that randomly nucleated liquid seeds, followed by rapid solidification in an amorphous matrix, during the Joule-heating-up period play an important role especially in liquid-to-solid transformation. Under some processing conditions, super-grains sized 6-8 ${\um}m$ were produced by the lateral growth from the initial seeds, without any artificially control.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.150-155
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• 2000

In this study, deformation analysis for solid-liquid coupled structure has been performed using explicit finite element program In order to model the behavior of liquid, SPH (Smooth Particle Hydrodynamics) algorithm was adopted. Crash test and simulation for the hydro-type impact energy absorber were given as an example of industrial application. The obtained good correlation between the test results and simulation reveals that the proposed method could be used effectively for the structural analysis of solid-liquid coupled problems

• Applied Microscopy
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• v.36 no.spc1
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• pp.19-24
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• 2006

The alumina-aluminum solid-liquid interfaces were directly observed at atomic scale by heating the alumina single crystal in high-voltage electron microscope (HVEM) owing to the electron beam damage processes, Atomic ordering in the first several layers of the liquid was clearly resolved adjacent to the alumina surface and its relevance to the single crystal growth was examined with the real-time observations.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.61-72
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• 1995

The author performed radionuclide esophageal transit studies(RETS) with liquid and solid boluses using the same day protocol in 90 normal controls and 164 patients with various primary esophageal motility disorders who were diagnosed by manometric criteria and clinical courses. The authors calculated mean esophageal transit time(MTT) and mean residual retention(MRR) in each of the liquid and solid studies, and classified time-activity curve(TAC) patterns. The normal criteria of RETS with liquid bolus were MTT<24 sec, MRR<9%, and the TAC pattern that showed rapid declining slope and flat low residual(Type 1). The normal criteria of RETS with solid bolus were MTT<35 sec, MRR<9% and TAC of type 1. With these normal criteria, the sensitivity and the specificity of the liquid study were 62.2 % and 97.8%, respectively. The sensitivity increased to 75.4% with the solid study. The author also found that the RETS was highly reproducible. The achalasia typically showed no effective emptying of both liquid and solid boluses during the whole study period, and was well differentiated by its extremely long transit time and high retention from the other motility disorders. The diffuse esophageal spasm (DES) and nonspecific esophageal motility disorder(NEMD) showed intermediate delay in transit time and increased retention. In the groups of hypertensive lower esophageal sphincter(LES), hypotensive LES and nutcracker, there noted no significant difference with the normal control group in terms of MTT and MRR. The DES and NEMD could be more easily identified by solid studies that showed more marked delay in MTT and increased MRR as compared with the liquid study. In conclusion, esophageal scintigraphy is a safe, noninvasive and physiologic method for the evaluation of esophageal emptying.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1095-1101
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• 1995

Numerical analysis of vertical solidification process allowing solid-liquid density change is performed by a hybrid method between a winite volume method (FVM) and a finite element method (FEM). The investigation focuses on the influence of solid-liquid density change and cooling rates on the motion of solid-liquid interface, solidified mass fraction, temperatures and thermal stresses in the solid region. Due to the density change of pure aluminium, solid-liquid interface moves more slowly but the solidified mass fraction is larger. The cooling rate of the wall is shown to have a significant influence on the phase change heat transfer and thermal stresses, while the density change has a small influence on the motion of the interface, solidified mass fraction, temperature distributions and thermal stresses. As the cooling rate increases, the thermal stresses become higher at the early stage of a solidification process, but it has small influence on the final stresses as the steady state is reached.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.167-170
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• 1997

For the optimal net shape forging of semi-solid materials (SSM), it is important to predict the deformation for variation of strain rate. It should be necessruy to conduct a formation of stress-strain curve in semi-solid alloys for analysis of the thixoforming process. Particularly, important problem to application of computer aided engineering in SSM processing is to prevent a segregation of liquid component during compression process. The liquid segregation is studied as multistage change of the strain rate and test piece size to prevent the liquid segregation during the compression process. The compression test for semi-solid aluminium alloy with a controlled solid fraction is performed by dynamic material test system with a furnace. Moreover morphology of structure and fraction of pore are investigated through compression test.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.234-237
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• 2008

It was reported that the semi-solid forming process has many advantages over the conventional forming process, such as a long die life, good mechanical properties and energy savings. It is very important, however, to control liquid segregation to gain mechanical property improvement of materials. During forming process, Rheology material has complex characteristics, thixotropic behavior. Also, difference of velocity between solid and liquid in the semi-solid state material makes a liquid segregation and specific stress variation. Therefore, it is difficult for a numerical simulation of the rheology Process to be Performed. General Plastic or fluid dynamic analysis is not suitable for the behavior of rheology material. The behavior and stress of solid particle in the rheology material during forging process is affected by viscosity, temperature and solid fraction. In this study, compression experiments of aluminum alloy were performed under each other tool shape. In addition, the dynamics behavior compare with Okano equation to Power law model which is viscosity equation.

• Korean Membrane Journal
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• v.9 no.1
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• pp.27-33
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• 2007

PVDF membrane formation via TIPS was performed for PVDF/DBP and PVDF/DMP systems. PVDF/DBP system showed solid-liquid phase separation behavior, while PVDF/DMP system has liquid-liquid phase separation characteristic as well as solid-liquid phase separation characteristic. PVDF contents and cooling conditions had great influence on structure, and the effects of each parameter were examined. Spherulitic structure was obtained due to the dominant PVDF crystallization. Diluent rejected to the outside of spherulite occupied the surface of the PVDF spherulites to result in the microporous spherulite formation and micro-void between spherulites. PVDF/DMP system had competitive solid-liquid and liquid-liquid phase separation depending on the cooling path.