• Journal of the Korean Geosynthetics Society
• /
• v.14 no.1
• /
• pp.33-41
• /
• 2015

In this study, laboratory tests (flow, unit weight, unconfined compressive strength and bleeding tests) were performed to evaluate engineering properties of treated soil to improve pipe mixing method. As result, flow and bleeding properties are proportional to the water contents. The unit weight and unconfined compressive strength is decreased as the water contents increased. Comparing equipments contact pressure with bearing capacity of the mixed soil for dozer, backhoe and belt conveyor are immediately appliable. The applicable water content range is estimated from 80% to 200% by pipe mixing method using cement. Also, The design chart is developed from the results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.6
• /
• pp.797-803
• /
• 2010

A vehicle door impact beam made of a thin sheet of steel has been constructed using hot stamping technology with the aim of ensuring occupant safety in the event of a side collision. This technology has been used to increase the strength of the vehicle body parts and to reduce the weight of the door impact beam as well as the number of work processes. Mechanical tests were performed to determine the material properties of the hot-stamped specimen and the results of the tests were used as input data in stamping and structural simulation in order to obtain the optimal design of door impact beam. The strength of the hot-stamped door impact beam increased to a value that was 102% higher than that of conventional pipe-shaped door impact beam. A weight reduction of 34% was also achieved.

• Journal of the Korean Applied Science and Technology
• /
• v.29 no.4
• /
• pp.599-609
• /
• 2012

The objective of this research is to reuse and recycle the oyster shell wastes as a useful of antioxidant beads for foodstuff preservation through the treatment of oyster shell and seaweed pulp. This research is divided into two parts. In the first, designing and preparation of pilot scale condition was accomplished. The second part dealt with establishing the optimized manufacturing condition for [A],[B],[C-a],[C-b] compounds, and analyzing these products. The pilot scale preparation was composed of modify synthesized seaweed pulp / Cl-starch and it's various bead form were prepared with various weight ratios using polar protic solvents. In addition, with increased seaweed pulp content in the blends, antibacterial property values of seaweed pulp/Ag-oyster shell blend was decreased, however, the antioxidant and bead's solidity properties increased.

• Journal of IKEEE
• /
• v.17 no.2
• /
• pp.135-139
• /
• 2013

This paper presents the 8-channel active module operated in Ka-band. The module is designed for the mobile satellite communication antenna systems, and the module structure has the merit to minimize the size and weight of the antenna systems by 30% compared with the conventional systems using the active module composed of single channel. This module was designed to be optimally operated by prohibiting the electrical interference among the individual channels. From the test results of the fabricated 8-channel active module, it can be confirmed that the maximum channel gain error is ${\pm}1.3dB$, the minimum channel output power is 21.5dBm, and the maximum gain variation by phase control is ${\pm}1.0dB$.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.31 no.5
• /
• pp.243-250
• /
• 2018

In this paper, design technique using genetic algorithms(GA) for design optimization of composite leaf springs is presented here. After the initial design has been validated by the car plate spring as a finite element model, the genetic algorithm suggests the process of optimizing the number of layers of composite materials and their angles. Through optimization process, the weight reduction process of leaf springs and the number of repetitions are compared to the existing algorithm results. The safety margin is calculated by organizing a finite element model to verify the integrity of the structure by applying an additive sequence optimized through the genetic algorithm to the structure. When GA is applied, layer thickness and layer angle of complex leaf springs have been obtained, which contributes to the achievement of minimum weight with appropriate strength and stiffness. A reduction of 65.6% original weight is reached when a leaf steel spring is replaced with a leaf composite spring under identical requirement of design parameters and optimization.

• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.1
• /
• pp.88-97
• /
• 1998

Large aluminium extrusions can be used in rolling stocks and high speed vessels to reduce weight and labor cost. As sandwich plates with corrugated core have enough strength in transverse and longitudinal direction, welding lines to connect members are reduced and transverse members to strength longitudinal members are not required. However, for proper design of aluminium extrusion plates, understanding of structural behaviors of the exclusions are necessary. In this paper, at first, detailed finite element analysis is carried out to understand structural behavior. And then, simple theoretical formulas for design purpose are proposed using the orthotropic plate theory. Shear stresses resulting from end twisting which is characteristics of deep aluminium extrusion plates can also be calculated by the simple theoretical formula. Comparison with the results by detailed finite element analysis shows good accuracy of the proposed simple formulas. The simple formulas can be useful in repetitive analysis in the initial design stage.

• Journal of the Korean GEO-environmental Society
• /
• v.25 no.6
• /
• pp.5-12
• /
• 2024

Currently, a grouting method that minimizes damage to the reservoir embankment by injecting solidification agent at low pressure is commonly used to ensure waterproofing and safety of the embankment, but the use of solidification agents can cause issues, such as a decrease in durability and a lack of clear method for determining the mixing ratio. In this study, when the base ground and solidification agent were stirred and mixed at various weight mixing ratios, the permeability coefficient and strength of the mixture were confirmed through laboratory tests, and the optimal mixing ratio was suggested through analysis of the test results. The specimen for the laboratory test was produced considering the mixing ratio of the solidification agent. The specimen for the permeability coefficient test was tested by producing one each of cohesionless and cohesive soil for a mixing amount of 1.5 kN/m³ of solidification agent, and the permeability test results confirmed that the water barrier performance was secured below the permeability coefficient value required by various design criteria. A total of 24 specimens for the strength test were produced, 3 for each of 5 mixing amounts for cohesive soil and 3 mixing amounts for cohesionless soil. The strength test results showed that the uniaxial compressive strength tends to increase linearly with increasing curing time for both cohesionless soil and cohesive soil when the mixing amount is less than 2.0 kN/m³. Therefore, the optimal mixing ratio applied to the site is determined to be mixing amount of 1.5 kN/m³ and 2.0 kN/m³. Finally, numerical analysis reflecting test results was conducted on design case for improvement projects for aging reservoirs embankment to verify the water barrier performance and safety improvement effects.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.2
• /
• pp.73-84
• /
• 1993

In this research, configuration design optimization of plane truss structure has been tested by using decomposition technique. In the first level, the problem of transferring the nonlinear programming problem to linear programming problem has been effectively solved and the number of the structural analysis necessary for doing the sensitivity analysis can be decreased by developing stress constraint into member stress approximation according to the design space approach which has been proved to be efficient to the sensitivity analysis. And the weight function has been adopted as cost function in order to minimize structures. For the design constraint, allowable stress, buckling stress, displacement constraint under multi-condition and upper and lower constraints of the design variable are considered. In the second level, the nodal point coordinates of the truss structure are used as coordinating variable and the objective function has been taken as the weight function. By treating the nodal point coordinates as design variable, unconstrained optimal design problems are easy to solve. The decomposition method which optimize the section areas in the first level and optimize configuration variables in the second level was applied to the plane truss structures. The numerical comparisons with results which are obtained from numerical test for several truss structures with various shapes and any design criteria show that convergence rate is very fast regardless of constraint types and configuration of truss structures. And the optimal configuration of the truss structures obtained in this study is almost the identical one from other results. The total weight couldbe decreased by 5.4% - 15.4% when optimal configuration was accomplished, though there is some difference.

• Journal of the Korean Society for Railway
• /
• v.19 no.6
• /
• pp.717-726
• /
• 2016

Emergency tracks are necessary in case a broken down train evacuates, a train needs to make way for a faster train behind it, or a train suddenly stops and following trains must avoid colliding with it. Magnetic Levitated (maglev) Trains can change track to enter an emergency track using a segmented switch or a traverse switch. On a traverse switch, a train can change its track when the part of the track that the train is on moves to the other track. Currently manufactured Maglev trains have two bodies and the total length is 25 meters. If a traverse switch is used, it will only require 30 meters of track to move the train to the other track, so, when it comes to efficiency of costs and space, the traverse switch surpasses the articulated switch. Therefore, in this paper, an optimized design to secure structural safety and weight lightening is suggested. To achieve these results, the heights of the piled concrete and girders which are both placed on the top of the traverse switch, are set as design variables. The Finite Element Method (FEM), in application of kriging and in the design of the experiments (DOE), is used. Maximum stress, deformation, and structural weight are compared with the results, and through this process structural safety and weight lightening is proven.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.7
• /
• pp.992-1001
• /
• 2023

OWEC (Overtopping Wave Energy Converter) is a wave power generation system using the wave overtopping. The performance and safety of the OWEC are affected by wave characteristics, such as wave height, period. To mitigate this issue, optimal OWEC designs based on wave characteristics must be investigated. In this study, the environmental conditions along the Ulleungdo coast were used. The hydraulic efficiency of the OWEC was calculated using SPH (Smoothed Particle Hydrodynamics) by comparing 4 models that changed the substructure. As a result, it was possible to change the substructure. Through design optimization, a new truss-type structure, which is a substructure capable of carrying the design load, was proposed. Through a case study using member diameter and thickness as design variables, structural safety was secured under allowable stress conditions. Considering wave load, the natural frequency of the proposed structure was compared with the wave period of the relevant sea area. Harmonic response analysis was performed using wave with a 1-year return period as the load. The proposed substructure had a reduced response magnitude at the same exciting force, and achieved weight reduction of more than 32%.