• Journal of The Korean Society of Agricultural Engineers
• /
• v.51 no.5
• /
• pp.51-58
• /
• 2009

The total recovery ratio test on undisturbed clay soil sampling in the field and the finite element method analysis on modified static state of penetration process were conducted for the purpose of deciding the most important factor among the shape factors of thin wall tube. The adhesion between tube wall and soil did not decrease although internal clearance ratio of tube increased within the little change of tube area ratio. The most part of disturbance occurred in the tip of sampling tube during the penetration. The longitudinal displacement was larger than the lateral displacement because soil was confined laterally after being entered into tube, and also the longitudinal displacement was larger in the upper part of the sample tube than in the lower part.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.51 no.5
• /
• pp.59-68
• /
• 2009

In this study, it was developed that the software could be used to estimate consolidation settlement by curve fitting method according to Terzaghi's consolidation theory on the condition of gradual incremental loading, and the method of estimating settlement caused by lateral displacement was suggested, in which the settlement was calculated from the difference between the settlement calculated with the developed software using the early part of measured data and the settlement measured for the short duration from the beginning of embankment in the field. The verification of the suggested method of estimating settlement caused by lateral displacement showed good results.

• Journal of Korean Society for Quality Management
• /
• v.41 no.4
• /
• pp.693-708
• /
• 2013

Purpose: This study is to develop an evaluation model for analysis of CMMS Implementation status and provide CMMS advancement methods to maximize implementation effect through the evaluation model. Methods: After extracting common modules from CMMS packages and establishing evaluation standard for each module, then the evaluation standard is applied to 33 Korean companies for evaluating their own current implementation status. Results: Preventive maintenance and analysis information modules were considered the most vulnerable in Korean companies which have introduced CMMS packages. And the reason why preventive maintenance is vulnerable is that there is poor build-up of their own preventive maintenance standards. Conclusion: Korean companies which will introduce CMMS need to make preventive maintenance standards, and data of the materials and the equipment to improve the effectiveness in advance.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.47 no.5
• /
• pp.43-49
• /
• 2005

In this study. it was suggested that the elastic model to analyze the behavior of pore water pressure in saturated sand specimen on the condition of non-drainage. The model based on the experiments which were performed for the relationships between the pore water pressure and the grain size of specimen, and effective stress, respectively. The suggested model embodied the pore water and soil grain as separate elastic springs of different stiffness. The springs were joined parallel and the axial strains were restricted to the same deformation. The suggested model was well consistent with the experiments.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.47 no.4
• /
• pp.43-52
• /
• 2005

It is known in some literatures that the B value is not equal to unity in saturated soil when effective stress is given, in which the B Value is the ratio of measured excess pore water pressure and isometric loading pressure. In this study the B value was measured on various effective stresses and on various incremental loading stresses in various grain size of specimens with saturated sand. The test results showed that the B value was affected largely by grain size of sand in specimen and the amount of effective stress. There was the semi-logarithmic relationship between B value and effective stress, and also there was the linear relationship between the gradient of the former semi-logarithmic relationship and grain size of specimen.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.56 no.1
• /
• pp.101-107
• /
• 2014

It has been known that Terzaghi's consolidation theory is not well consistent with the consolidation phenomenon on the soft clay ground, but this theory has still been adopted normally in practice because there is no method for estimating the consolidation settlement and rate easier than Terzaghi's theory. It is impossible to map whole part of consolidation settlement vs time curve to the curve of Terzaghi'z average degree of consolidation. If the primary consolidation and the secondary compression are happened same time, it would be useless of trying to find the end of primary consolidation, but it is needed for using Terzaghi's theory that the end of consolidation is determined to the time of beginning consistency between the final settlement analyzed with curve fitting and the experimented consolidation settlement.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.10
• /
• pp.1259-1263
• /
• 1999

In this paper, a method to guarantee system continuity is developed, which can be applied to discontinuity problem in the time domain of restructurable control system. This method can be summarized as input alternation using weight change considering convergence speed of system mode. Input is changed from 'system continuity guarantee input,' which is defined as a input that minimizes the change of state variables, to 'alternative controller input,' which is selected by Neil's PI/EAM[3]. AIDC aircraft model is used for simulation. By showing the waveform of system input and state variable, we can sure that this method is effective for depression of system shock like jerk.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.12
• /
• pp.1047-1054
• /
• 2008

In this paper, the molecular dynamics (MD) simulations are performed with single-crystal copper blocks under simple shear and simple tension to investigate the effect of size and crystal orientation. There are many variances to give influences such as deformation path, temperature, specimen size and crystal orientation. Among them, the crystal orientation has a primary influence on the volume averaged stress. The numerical results show that the volume averaged shear stress decreases as the specimen size increases and as the crystal orientation changes from single to octal. Furthermore, the Schmid factor and yield stress for crystal orientation are evaluated by using the MD simulation on the standard triangle of stereographic projection.

• Journal of Powder Materials
• /
• v.22 no.4
• /
• pp.247-253
• /
• 2015

The sintering mechanisms of nanoscale copper powders have been investigated. A molecular dynamics (MD) simulation with the embedded-atom method (EAM) was employed for these simulations. The dimensional changes for initial-stage sintering such as characteristic lengths, neck growth, and neck angle were calculated to understand the densification behavior of copper nano-powders. Factors affecting sintering such as the temperature, powder size, and crystalline misalignment between adjacent powders have also been studied. These results could provide information of setting the processing cycles and material designs applicable to nano-powders. In addition, it is expected that MD simulation will be a foundation for the multi-scale modeling in sintering process.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.56 no.6
• /
• pp.159-167
• /
• 2014

In this study the process of normalizing hydraulic head loss rate was developed for the purpose of estimation of seepage blocking state at each seepage segment in sea dike embankment. Pore water pressure sensors were installed with some interval along seepage path, then the hydraulic head loss rate at each segment between pore water pressure sensors was calculated, and then the calculated hydraulic head loss rate was normalized based on seepage path length. The comparison of normalized hydraulic head loss rates showed that the cross section of sea dike embankment was homogeneous approximately and the width of cross section was long enough to blocking tide water.