• Journal of the Korean Geotechnical Society
• /
• v.15 no.1
• /
• pp.53-62
• /
• 1999

Despite the frequent use of the soil-reinforced segmental retaining wall (SRW) system, the roles of the different components comprising the system, such as facing blocks, reinforcements, backfill, and block/backfill interface, are still not fully understood, and much still need to be investigated for more safe and economical design/analysis method. Therefore, this study was undertaken with the aim of understanding the effect of the shear strength of backfill material and the reinforcement stiffness on the behavior of SRW by using the finite element analysis. In the analysis the details of construction sequence and the SRW components were carefully modeled, and a parametric study was performed in order to investigate the effects of shear strength of backfill soil and reinforcement stiffness on the wall displacement and earth pressure, the vertical stress under the reinforced block, the reinforcement and block/reinforcement connection forces. Implications of the findings from this study to current design practices were discussed in detail.

• Earthquakes and Structures
• /
• v.24 no.3
• /
• pp.205-215
• /
• 2023

Currently, many studies are underway at home and abroad on the seismic performance evaluation and dry construction method of the masonry structure. In this study, a dry stack masonry wall system without mortar using concrete blocks is proposed, and investigate the seismic performance of dry filling wall frames through experimental studies. First, two types of standard blocks and key blocks were designed to assemble dry walls of concrete blocks. And then, three types of experiments were manufactured, including pure frame, 1/2 height filling wall frame, and full height filling wall frame, and cyclic load experiments in horizontal direction were performed to analyze crack patterns, load displacement history, rebar deformation yield, effective stiffness change, displacement ductility, and energy dissipation capacity. According to the experimental results, the full height filling wall frame had the largest horizontal resistance against the earthquake load and showed a high energy dissipation capacity. However, the 1/2 height filling wall frame requires attention because the filling wall constrains the effective span of the column, limiting the horizontal displacement of the frame. In addition, the concrete block was firmly assembled in the vertical direction of the wall as the horizontal movement between the concrete blocks was allowed within installation margin, and there was no dropping of the assembled concrete block.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.1
• /
• pp.122-129
• /
• 2005

On the cluster system, the parallel code of rigid-plastic FEM has been developed. The cluster system, Simforge, has 15 processors and the total memory is 4.5GBytes. In the developed parallel code, the distributed data of the column-wise partitioned stiffness are stored as the compressed row storage and the diagonal preconditioned conjugate gradient solver is applied. The analysis of block upsetting is performed with the parallel code on Simforge cluster system. In this paper, the analysis results are compared and discussed.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.249-249
• /
• 2006

We have prepared an amphiphilic wedge-coil molecule consisting of a hydrophobic wedge-like segment and a hydrophilic poly(ethylene oxide) (PEO) segment. The wedge-coil block molecule self-assembles into cylindrical nanofibers in both polar as well as nonpolar solvents. Remarkably, the resulting nanofibers, as solvent polarity change from water to n-hexane, change from highly flexible coil-like to stiff rod-like characteristics. This dynamic switching in the stiffness of the nanofibers in response to solvent polarity is attributed to the structural inversion of cylindrical core from bulky dendritic segments with amorphous nature to crystallizable linear PEO segments.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.05a
• /
• pp.204-205
• /
• 2014

Among common test methods of assessing structure safety for existing lightweight walls, the criteria of the quality assessment of the horizontal static load resistance has been considered ambiguous. In the current study, therefore, an experiment was conducted to figure out the standardized assessment criteria of the lightweight wall's horizontal static load resistance. Based on the findings of the experiment with gypsum board and ALC block walls, an acceptable amount of each standard and the variables of the stud wall arising from the appropriate load (1000N) on the wall in a daily life were accounted for, arbitrarily setting the maximum deformation amount below 15mm.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.2
• /
• pp.238-243
• /
• 2015

Recently, the use of assembled-type drills as environmentally friendly products has expanded because the shanks of drills can be reused by replacing the tip when the tools are worn or cut. In addition to their precision and endurable stiffness with respect to the cutting force, assembled-type drills need no stricture because of thermal deformation, which makes replacement easily. In this study, we developed novel assembled-type drills and compared their characteristics, such as the precision, stiffness, and thermal deformation, with those of conventional drills. The new drills exhibited a precision over IT 8 class and no changes in dimensions due to thermal deformation, such that we can change the assembly easily with durability.

• Korean Journal of Agricultural Science
• /
• v.38 no.4
• /
• pp.711-716
• /
• 2011

Casein micelles are the basic building block of rennet-induced gels. The stiffness of these gels is increased with reaction time. This is probably due to the continuous participation of activated casein micelles into growing network. Dual binding model of casein micelles, which explains assembly of casein and colloidal calcium phosphate, can provides fairly reasonable explanation for the changes in mechanical properties of rennet-induced gels made from different milk pHs and varying colloidal calcium phosphates. The changes in stiffness of these gels would be used for controlling textural properties of cheeses.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.7 no.5
• /
• pp.67-76
• /
• 1997

In this paper, a theoretical study is presented for the force control of a miniature robotic manipulator which is driven by a pair of piezo-electric bimorph cells. In the theoretical analysis, one finger is modeled as a flexible cantilevers with a force sensor at the tip and the finger is a solid beam. The robotic finger is used to hold the objects with different stiffness such as an iron block and a living insect and a moving objcet. So it is very important to develop an adequate controller for the holding operation of the finger. The main problems in force controlling are overdamping, overshoot and unknown environment(such as the stiffness of object and unknown plant parameters). So, the main target is propose the new fuzzy compensation for unknown environment and incease the system performance. The fuzzy compensation is implemented by using PI-type fuzzy approach to identified unknown environment. And the result of proposed controller was compared with the conventaional PID and optimal controller.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.308-319
• /
• 2005

Piezo-ceramics are special materials which transform energy between mechanical and electrical forms. Bender-elements are composite materials consisting of thin piezo-ceramics and elastic shims, and are widely used as actuators and transducers in the field of electronics, robotics, autos and mechatronics utilizing the effectiveness of energy transformation capability. In geotechnical engineering, commercial bender-elements are used in laboratory as source and receiver in the measurements of soil stiffness. The elements were built by using various metal shims sandwiched between piezo-ceramics and coating over the composite in the research. A pair of elements were buried in a concrete block and used as source and receiver to measure the stiffness of the concrete. The test results were verified by comparing with the resonant column testing results. In a preliminary stage of the development of an in-situ seismic testing equipment using bender-elements for soft clay materials, shear waves were generated and measured by burying the elements in the barrel of kaolinite and water mixture. The measured shear wave signals were so distinct for the first-arrival pick that applicability of the elements in the field measurements is very promising.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.2
• /
• pp.30-37
• /
• 2014

In this study, we studied how to perform the structural analysis which need a large-capacity flash memory with the computer program when the flash memory storage of a personal computer has no enough room for the analysis of structure. As one of the solutions of this problem, the blocking method of stiffness matrix, which is a method that stiffness matrix is divided by a few blocks and each block is sequentially used for the calculation of matrix decomposition, is proposed and an algorithm available in computer program is derived on the method. Finally, A structural analysis program (sNs) based on this study is developed and the correctness and efficiency of the algorithm is founded through some examples which are fundamental in structural analysis.