• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1199-1204
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• 2000

This study concerns the cement-solidification/stabilization of the municipal waste incineration fly-ash. Compressive strength and leaching test of heavy metals were evaluated for varying types and ratios of cements and the effects of some additives of Hauyne clinker and slag were also discussed. In the cases of using cement binders more than 10%, the compressive strength after 3 days showed the values over $20kgf/cm^2$. Type III cement and Hauyne clinker improved the compressive strength, especially early strength. And the values of leaching test showed that cement-solidification is effective method to stabilize heavy metals especialy when using type III cement and adding Hauyne clinker and slag,.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1120-1125
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• 2004

Welding characteristics of STS304 stainless steel and Inconel 600 using a continuous wave Nd:YAG laser are experimentally investigated. Alloy 600 being used in steam generator tubing of pressurized water reactor(PWR) exposed to some corrosion environment, stress corrosion cracking can occur on this material. Presented here are the results from a series of experiments in which dissimilar metal welds were made using the gas tungsten arc welding process with pure argon shielding gas. But It is well known that solidification cracking susceptibility of austenitic alloys depends on the solidification temperature range and amount/distribution of solute rich liquid that exists at the terminal stages of solidification. An experimental study was conducted to determine effects of welding parameters and to optimize those parameters that have the most influence on eliminating or reducing the extent welding zone formation at dissimilar metal welds.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.4
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• pp.182-186
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• 2003

The photovoltaic industry has been forced to lower the production cost in many ways. Ingot preparation technology is growing rapidly toward large-scale production. Multicrystalline silicon ingot of 69 cm square cross section, 240kg has been produced with fully automated equipment. During solidification, heat has been extracted from the bottom of the crucible through the graphite pedestal moving downward. The characteristics of the large ingot grown in this method are found to be uniform structurally and electrically.

• Journal of Korea Foundry Society
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• v.3 no.2
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• pp.83-91
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• 1983

In this paper analytical and numerical methods fur analysis of solidification of castings are described, and the matrix method, one of numerical method, where the nodal point is designated on the element boundary was adapted. The cooling curve obtained by experimental values, when cast steel (0.29%C. 0.62%Si) was poured into $CO_2$ mold, is compared with that of computed values by exploiting computer (V77-600 Data Proceeding System, UNIVAC). The computed value is nearly approximation to the experimental. But the computed value shows a tendency that is a little higher than the experimental in solid-liquid coexisting temperature ranges and much lower than the experimental after solidification. It is considered to result from the lacks and difficulties of ultimately appropriate adaptation of various physical properties and also air cap between castings and mold.

• Journal of Korea Foundry Society
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• v.20 no.2
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• pp.80-88
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• 2000

Continuous casting equipment was designed to cast the metallic uranium rods, and a thermal analysis was carried out to calculate the temperature and solidification profiles. Fluid flow and heat transfer analysis model including the effects of phase change was used to simulate the continuous casting process by finite volume method. In the design of continuous casting equipment, the casting speed, pouring temperature and cooling conditions should be considered as significant factors. In this study, the effects of casting speed, pouring temperature, and air gap between the uranium and mold were investigate. The results represented that the temperature and solidification profiles of continuous casting equipment varied with the casting speed, pouring temperature, and air gap.

• Journal of Welding and Joining
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• v.10 no.3
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• pp.1-12
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• 1992

A literature review was conducted to survey informations available on the welding metallurgy of aluminum alloys and its effect on fusion weldability, especially on solidification cracking and pore formation. Solidification cracking behavior of Al weld is a complicate matter as compared to other high alloys, where a relatively simple Fe-X(most detrimental elements S, P, B, Si, etc) binary diagram can be successfully applicable. Both additive and synergistic effects of elements should be considered together. A same element play a different role from system to system. Porosity, caused by hydrogen contamination of the weld is one of the most troublesome welding problems. The primary sources of hydrogen are believed to be an absorbed moisture on the filler metal or base metal and in the shielding gas. It is extremely important that reliable quality-control procedures be employed to eliminate all possible sources of hydrogen contamination. Selection of proper process and parameters is sometimes more important than controlling of alloying elements in order to make a defect-free weld.

• Journal of Advanced Marine Engineering and Technology
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• v.7 no.1
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• pp.79-90
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• 1983

The examination for the changes of structures and mechanical properties in directionally solidified Al-Fe-Ni alloys containing the small amount of Fe and Ni was carried out by the varying the composition and solidification rate R of alloy, provided that the temperature gradient was 80 .deg.C/cm. The result were obtained as follows. A) In proportion to the increase of the solidification rate (R), the crystallized phase of this alloy was changed from the Ribbon-type structure to the Rod-type structure. B) The strength was rapidly increased in the changing process of composite shape from the Ribbon-type to the Rod-type with the solidification rate (R) increasing. C) The fiber stress (${\sigma}^f$) and Young's modulus ($E_f$) calculated for the Rod-type structure were 220 kg/$mm^2$ and 11, 800 kg/$mm^2$ respectively, which were in good accord with the rule of Mixtures.

• Journal of Mechanical Science and Technology
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• v.19 no.7
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• pp.1488-1502
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• 2005

A three dimensional model was developed to analyze the mold filling and solidification in the casting processes. The model uses the VOF method for the calculation of the free surface and the modified Equivalent Specific Heat method for the treatment of the latent heat evolution. The solution procedure is based on the SIMPLER algorithm. The complete model has been validated using the exact solutions for phase change heat transfer and the experimental results of broken water column. The three-dimensional model has been applied to the benchmark test and the results were compared to those from experiment, a two-dimensional analysis, and another three dimensional numerical model.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.1-11
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• 2000

This study investigates the problem of phase change from liquid to solid in the inviscid stagnation flow. The solution of dimensionless governing equations is determined by the three dimensionless parameters of (temperature ratio/conductivity ratio), Stefan number, and diffusi-vity ratio. The solution at the initial stage of freezing is obtained by expanding it in powers of time, and the final equilibrium state is determined from the steady-state governing equations. The equilibrium state is dependent on (temperature ratio/conductivity ratio), but is independent of Stefan number and diffusivity ratio. The effect of fluid flow on the pure conduction problem can be clearly seen from the solution of the initial stage and the final equilibrium state, and the characteristics of the solidification process for all the dimensionless parameters are elucidated.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.80-85
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• 1997

Studies on particles formed in the laser melted zone (LMZ) of sensitized Ni base Alloy 600 have been carried out using microscopic equipments. Most of them were identified as TiN type and MgS type particles were also found in the cell boundaries. All of the particles were located in the cellular solidification region, but no particle was formed in the plane front solidification regions of the LMZ. Cr carbides which had formed during sensitization treatment were completely melted during laser surface melting and hardly re-precipitated during the matrix solidification.