• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.97-107
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• 2014

Settlement prediction has been conducted using Hyperbolic, Hoshino, and Monden methods, etc in the fields. These methods are only able to predict settlement after finishing the final filling stage. A new method is proposed to make up for such a weak point. This method was named as SPSFC (Settlement Prediction for Staged Filling Construction) method, which can be able to predict the settlement both the final filling stage and the staged filling from the initial filling stage in soft ground. To verify the applicability of the SPSFC method, firstly. The settlement predicted by the existed methods are compared with that obtained by the SPSFC method. The comparison results indicate the SPSFC has enough reliability to use for prediction of settlement. Secondly. by analyzing the settlement data measured during the initial filling stage, the soil parameters which need to predict the settlement are obtained by the SPSFC method. Then using the obtained soil parameters the time-settlement curve is predicted and compared. The predicted settlement is well matched with the measured one. From the study, the SPSFC method can be possible to predict settlement during the staged filling with only the initial settlement data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04a
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• pp.620-625
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• 1995

Finite element analysis tool was developed to analyze the casting process. Generally, casting processes consists of mold filling and solifification. In order to investigate the effects of process variables and to predict the defects, both filling and solidiffication process were simulated simultaneously. At filling process, especiallywe consider thermal coupling to investigate thermal history of material during the filling stage. And thermal condition at the final stage of filling is used as the initial conditions in a solidification process for the exact simulation of the actual casting processes. At mold filling process, Lagrangian-type finite element method with automatic remashing scheme was used to find the material flow. To avoid numerical instability in low viscous fluid, a perturbation method with artificial viscosity is adopted. At solififfication process, enthalpy-based finite element method was used to solve the heat transfer problem with phase change. And elastic stress analysis has been performed to predict the thermal residual stress. Through the FE analysis, solidiffication time, position of solidus line, liquidus line and thermal residual stress are studied. Finite element tools developed in this study will be used process design of casting process and maybe basic structure for total CAE system of castigs which will be constructed afterward.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.17-29
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• 2012

To investigate the characteristics of shear strength and soil deformation in soft grounds, in which various vertical drains were placed, two hundreds field monitoring data of embankments performed in thirteen road construction sites at west and south coastal areas of the Korean Peninsula were collected. At first, the relationship between settlement and lateral displacement was investigated into three stages, in which embankment construction works were divided into initial filling stage, final filling stage and stage after complete filling. And then, the relationship of surcharge pressures and embankment heights with undrained shear strength of soft grounds were investigated. The investigation on settlement and lateral displacement illustrated that the increment of lateral flow to the increment of settlement was low during initial filling stage, but increased gradually with filling and showed largest during final filling stage. After complete filling, the lateral displacement was converged, even though the settlement was increased continuously. Therefore, most of lateral flow was occurred during embankment filling. The ratio of the lateral displacement increment to the settlement increment was 20% for initial filling stage, which coincided with the one presented by Tavenas et al.(1979), but became 50% for final filling stage, which was half of the one presented by Tavenas et al.(1979). However, the ratio reduced to 1% to 9%, which was quite lower than the one presented by Tavenas et al.(1979). Shear deformations, even shear failures, were predicted in soft grounds under initial undrained shear strength, since the design heights of embankments were higher than the yield height in all the sites. However, embankment construction would be possible since the yield height became higher than the design height due to improvement of shear strength of soft grounds with application of the vertical drains. In order to perform safely embankments for road constructions, the embankment loads should be designed not to be exceed 5.14 times the initial undrained shear strength of soft grounds and to be less than 3.0 times the undrained shear strength improved with application of vertical drains in soft grounds.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.110-122
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• 1996

Finite element analysis tool was developed to analyze the casting process. Generally, casting process consists of mold filling and solidification. Both filling and solidication process were simulated simultaneously to investigate the effects of process variables and to predict the defect. At filling process, thermal coupling was especially considered to investigate thermal history of material during the filling stage. And thermal condition at the final stage of filling is used as the initial conditions in a solidification process for the exact simullation of the actual casting processes. At mold filling process, Lagragian-type finite element method with automatic remeshing scheme was used to find the material flow. A perturbation method with artificial viscosity is adopted to avoid numerical instability in low viscous fluid. At solidification process, enthalpy-based finite element method was used to solove the heat transfer problem with phase change. And elastic stress analysis has been performed to predict the thermal residual stress. Through the FE analysis, solidification time, position of solidus line, liquidus line and thermal residual stress are found. Through the study, the importance of combined analysis has been emphasized. Finite element tools developed in this study will be used process design of casting process and may be basic structure for total CAE system of castings which will be constructed afterward.

• Journal of Korea Foundry Society
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• v.40 no.2
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• pp.34-42
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• 2020

The effects of the initial balancing pressure, filling pressure and maximum build-up pressure on the casting characteristics of the thick-wall thickness casting during the counter-pressure casting process were investigated. Water model experiment and a computer simulation were carried out to evaluate the characteristics during the filling and solidification stages in counter-pressure casting (CPC); as a reference, the low-pressure casting (LPC) process was used. The average dendrite cell size decreased with an increase in the solidification rate and maximum build-up pressure. A turbulent flow occurred during the filling stage of the LPC process, resulting in the formation of inner gas, while a lamellar flow pattern dominated during the CPC process and was more evident with an increase in the initial balancing pressure, improving the mechanical properties of the castings.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.635-641
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• 1996

This study was designed to evaluate the anti cariogenic effect of F in primers, bonding agents, composite resins or glass ionomer cements in enamel. Twenty-five extracted teeth were selected and a cavity was prepared on either the buccal or the lingual surface of each tooth. After pumicing and etching, the samples were divided into 5 groups. In group A, the samples were primed, bonded and filled with ART bond and Brilliant Enamel (Coltene, Switzerland). Group B composed of Optibond and Herculited XRV (Kerr, USA), group C composed of Syntac and Tetric(Vivadent, Lichtenstein), and group D composed of Scotch-bond Multipurpose and Z 100 (3M, YSA). In group E, the samples were filled with glass ionomer cement (Fuji II LC, Japan), All surfaces except the 2mm beyond the cavosurface margin of the sample were protected, and samples were then put into an acid buffer for 3 days to develop the initial caries. The samples were then sectioned through the filling body into thin wafers and then examined with a polarizing microscope under water imbibition. The fluoride in primer, bonding agent, or composite filling material did not prevent the initial caries in the enamel area adjacent to the filling body whereas the fluoride in the glass ionomer did prevent the initial stage caries.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.29-35
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• 2007

The main objective of this paper is to propose the optimal design method of forging process using genetic algorithm. Design optimization of forging process was doing about one stage and multi stage. The objective function is considered the filling of die. The chosen design variables are die geometry in multi stage and initial billet shape in one stage. We performed FE analysis to simulated forging process. The optimized preform and initial billet shape was obtained by genetic algorithm and FE analysis. To show the efficiency of GA method in forging problem are solved and compared with published results.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.119-126
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• 2019

For rockets using cryogenic liquid hydrogen or liquid oxygen, chilling is required to avoid cavitation and surge problems. Chilling is categorized by the initial chilling/filling stage and the low-temperature maintenance stage. In addition, to improve satellite insertion capability, a multi-ignition capability is required and accordingly chilling to prepare for the next ignition during low-gravity coasting is also required. This paper describes the overall aspects of filling and low temperature maintain marinating for the booster and the upper stage engine including chilling for multi-ignition.

• Structural Engineering and Mechanics
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• v.50 no.4
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• pp.563-573
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• 2014

In hydroforming, the general technique employed to overcome the problem of die corner filling consist in increasing the maximum fluid pressure during the forming process. This technique, in other hand, leads to other difficulties such as thinning and rupturing of the final work piece. In this paper, a new technique has been suggested in order to produce a part with complete filled corners. In this approach, two moveable bushes have been used. So, the workpiece moves driven by both bushes simultaneously. In the first stage, system pressure increases until a maximum of 15 MPa, providing aninitial tube bulge. The results showed that the pressure in this stage have to be limited to 17 MPa to avoid fracture. In a second stage, bushes are moved keeping the constant initial pressure. The punches act simultaneously at the die extremities. Results show that the friction between part and die decreases during the forming process significantly. Also, by using this technique it is possible to produce a part with reasonable uniform thickness distribution. Other outcomes of applying this method are the lower pressures required to manufacture a workpiece with complete filled corners with no wrinkling.

• Journal of Korean Society on Water Environment
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• v.37 no.5
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• pp.363-368
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• 2021

On the assessment results of the non-point source pollutant removability of bio-block using waste sewage sludge, at the reactor's initial operation stage, the removal efficiency of COD was slightly unstable. However, after the reactor was stabilized, the COD removal efficiency was higher in the reactor filled with bio-blocks compared to the reactor filled with broken stones. In terms of nitrogen and phosphorus, their removal efficiency was unstable at the initial stage of the reactor operation. This phenomenon was investigated through the bio-block elution experiments. Results indicated that nitrogen and phosphorus were eluted from the bio-blocks affecting their removal at the initial operation. Furthermore, based on elution tests conducted after the dry ashing of the waste sewage sludge, part of the nitrogen and phosphorus was eluted similar to the bio-block elution test results, although considerable amounts of nitrogen and phosphorus were reduced compared to the sludge cake. Prior to the use of the waste sewage sludge bio-blocks as a filter medium to remove non-point source pollutants, a stabilization period of 10 days was required. After the stabilization process, results showed similar characteristics as general aggregates. Moreover, to use the bio-block as a filter medium for the non-point pollutant removal, the filling ratio of 75% was the most suitable as it resulted in the highest nitrogen removal efficiency after the stabilization. The results of this study suggested that waste sewage sludge can be suitably recycled as a mixed raw material for the bio-blocks, with satisfactory application as a filter medium in artificial wetlands, stormwater runoff problems, stream water pollutants to eliminate non-point source pollutants.