• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.147-154
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• 2005

The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact Hence, for more rational and safe design of ship structures, it is of crucial importance to better understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1041-1050
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• 2011

An elasto-plastic finite element method using the theory of strain gradient plasticity is proposed to evaluate the size dependency of structural plasticity that occurs when the configuration size decreases to micron scale. For this method, we suggest a low-order plane and three-dimensional displacement-based elements, eliminating the need for a high order, many degrees of freedom, a mixed element, or super elements, which have been considered necessary in previous researches. The proposed method can be performed in the framework of nonlinear incremental analysis in which plastic strains are calculated and averaged at nodes. These strains are then interpolated and differentiated for gradient calculation. We adopted a strain-gradient-hardening constitutive equation from the Taylor dislocation model, which requires the plastic strain gradient. The developed finite elements are tested numerically on the basis of typical size-effect problems such as micro-bending, micro-torsion, and micro-voids. With respect to the strain gradient plasticity, i.e., the size effects, the results obtained by using the proposed method, which are simple in their calculation, are in good agreement with the experimental results cited in previously published papers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.1 s.24
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• pp.67-74
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• 2006

The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion rf the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact. Hence, for more rational and safe design rf ship structures, it is of crucial importance to better understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated secondary buckling behavior through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.2919-2924
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• 2011

The automatic drawer is used to absorb the movement shock and adjust its velocity when it opens and closes. The tube in shock-absorber is the cylindrical case which surrounds its parts and is made of acetal. The purpose of this study is to determine the quality stability of the tube in the shock-absorber in injection molding process. The tube which had been manufactured in the process with 4 cavity cooling unit was used. In this study, the analysis and test are carried out to determine its quality stability. Which are the quality analysis with numerical simulation and performance tests of the tube compared with one of foreign make. It is calculated that the injection press is 87.6 MPa and the deflections in X, Y, Z directions are ranged in 0.07~1.00 mm. When the researched tube is compared with the foreign made tube, the maximum bending compressive load is 231 kgf higher, average axial compressive load is 0.05 kgf higher, and the roughness(Ra) on the inner surface is $0.02\;{\mu}m$. lower. In the result, it is known that the quality of researched tube in injection mold process is stable and its performance is superior.

• Current Research on Agriculture and Life Sciences
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• v.31 no.3
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• pp.193-199
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• 2013

This study dyed rayon fabric using loess as a natural colorant. To obtain the optimal dyeing conditions, various dyeing conditions were examined (temperature, pH, time, and concentration). The color fastness was evaluated using standard washing and rubbing fastness tests. The results were as follows: The loess powder particle size ranged from 0.4 to $1.7{\mu}m$ with a distribution range of 1.1 to $1.4{\mu}m$, representing a fine and uniform manufactured loess powder. The loess component analysis showed a large amount of silicon dioxide and aluminum oxide. TheFT-IR spectra showed that the ammonium group in the rayon fabric produced N-H banding at $1,540cm^{-1}$. The highest K/S value for the rayon fabric was obtained when the pH was 8.0, and this value increased rapidly with a longer dyeing time and when increasing the loess concentration to 30% (w/v). Pre-treatment with a soybean solution produced the highest K/S value for the rayon fabric with a loess concentration of 30% (w/v). The SEM analysis showed a higher amount of loess adhered to the rayon fabric surface when increasing the loess concentration. However, pre-treatment with a cationic agent and soybean solution resulted in a much higher attachment of loess to the fabric surface. Thus, the experimental results showed that using a cationized fabric and pre-treatment with a soybean solution are more effective when dyeing rayon fabric with loess than when using only loess.

• Journal of Biomedical Engineering Research
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• v.27 no.5
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• pp.210-217
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• 2006

Many types of interspinous distraction devices (IDDs) have been recently developed as an alternative surgical treatment to laminectomy and fusion with pedicle screws for the treatment of the lumbar spinal stenosis (LSS). They are intended to keep the lumbar spine in a slightly flexed posture to relieve pain caused by narrowing of the spinal canal and vertebral foramen. However, their biomechanical efficacies are not well known. In this study, we evaluated the kinematic behaviors and changes in intradiscal pressure (IDP) of the porcine lumbar spine implanted with IDD. For kinematics analysis, five porcine lumbar spines (L2-L6) were used and the IDD was inserted at L4-L5. Three markers (${\phi}{\le}0.8mm$) were attached on each vertebra to define a rigid body motion for stereophotogrammetric assessment of the spinal motion in 3-D. A moment of 7.5Nm in flexion-extension, lateral bending, and axial rotation were imparted with a compressive force of 700N. Then, IDD was implanted at L3-L4. IDPs were measured using pressure transducer under compression (700N) and additional extension moment (700N+7.5Nm). In kinematic behaviors, insertion of IDD resulted in statistically significant decrease 42.8% at the implanted level in extension. There were considerable changes in ROM at the adjacent levels, but statistically insignificant. In other motions, there were no significant changes in ROM as well regardless of levels. IDPs at the surgical level (L3-L4) under compression and extension moment decreased by 12.9% and 18.8% respectively after surgery (p<0.05). At the superiorly adjacent levels, IDPs increased by 19.4% and 12.9% under compression and extension, respectively (p<0.05). Corresponding changes at the inferiorly adjacent levels were 29.4% and 6.9%, but they were statistically insignificant (p>0.05). The magnitude of pressure changes due to IDD, both at the operated and adjacent levels, were far less than the previously reported values with conventional fusion techniques. Our experimental results demonstrated the IDDs can be very effective in limiting the extension motion that may cause narrowing of the spinal canal and vertebral foramens while maintaining kinematic behaviors and disc pressures at the adjacent levels.

• Journal of the Korean Society for Railway
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• v.17 no.5
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• pp.355-364
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• 2014

The restrained volume changes of concrete due to variations of temperature and moisture produce transverse cracks in continuously reinforced concrete tracks (CRCTs). Such cracks are known to significantly affect the behaviors and long-term performance of CRCT. To investigate the effects of the transverse cracks on the behavior of CRCT and to develop more reasonable maintenance standards for cracks, in this study, the stress distribution of the track concrete layers (TCL) and the hydraulically stabilized base course (HSB) with transverse cracks were numerically predicted by a three dimensional finite element analysis when CRCT was subjected to train loads. The results indicate that the bending stresses of TCL and vertical stresses at the interfaces between TCL and HSB increased as the cracks were deepened. In addition, vertical stresses were locally concentrated near reinforcing steel in cracks in TCL when full-depth cracks developed, which may lead to punch-outs in CRCTs. Comparably, the effects of crack width and spacing were not as significant as crack depth. This study indicates that ensuring the long-term performance of CRCTs requires adequate maintenance not only for crack width and spacing but also for crack depth. Our results also show that locating HSB joints between sleepers is beneficial to the long-term performance of CRCTs.

• Journal of the Korean GEO-environmental Society
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• v.20 no.3
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• pp.21-30
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• 2019

Composite pile, which is composed of the steel pipe pile in which the large horizontal force acts and the PHC pile in which the small horizontal force acts by a special connecting devices, is being commercialized as a base material for civil engineering structures. The core of such a composite pile can be said to be a design criterion for estimating the joint position and stability of the connection device between steel pipe pile and PHC pile. In Korea, there is no precise specification for the location of composite pile joints. In the LH Design Department (Korea Land & Housing Corporation, 2009), "Application of composite pile design and review of design book marking" was made with reference to Road Design Practice Volume 3 (Korea Expressway Corporation, 2001). this is used as a basis of the design of the composite pile. It can not be regarded as a section change of the composite pile, so it has a limitation in application. Therefore, In this study, we propose a design criterion for the location of the section of the composite pile (joint of steel pipe pile and PHC pile) and evaluate the stability and economical efficiency of it by using experimental method and analytical method. Analysis of composite pile design data installed in 79 domestic bridges abutment showed that the stresses, bending moments, and displacements acting on the pile body and connection of the pile were analyzed. Through the redesign process, it was confirmed that the stresses generated in the connecting device occur within the allowable stress values of the connecting device and the PHC pile. In conclusion, the design proposal of composite pile joint location through empirical case study in this study is an improved design method considering both stability and economical efficiency in designing composite pile.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.141-152
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• 2022

As interest increases related to the development of eco-friendly energy, the offshore wind turbine market is growing at an increasing rate every year. In line with this, the demand for an installation vessel with large scaled capacity is also increasing rapidly. The wind turbine installation vessel (WTIV) is a fixed penetration of the spudcan in the sea-bed to install the wind turbine. At this time, a review of the spudcan is an important issue regarding structural safety in the entire structure system. In the study, we analyzed the current procedure suggested by classification of societies and new procedures reflect the new loading scenarios based on reasonable operating conditions; which is also verified through FE-analysis. The current procedure shows that the maximum stress is less than the allowable criteria because it does not consider the effect of the sea-bed slope, the leg bending moment, and the spudcan shape. However, results of some load conditions as defined by the new procedure confirm that it is necessary to reinforce the structure to required levels under actual pre-load conditions. Therefore, the new procedure considers additional actual operating conditions and the possible problems were verified through detailed FE-analysis.

• Composites Research
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• v.35 no.5
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• pp.303-308
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• 2022

PIC (Piecewise Integrated Composite) is a new concept for designing a composite structure with mosaically assigning various types of stacking sequences in order to improve mechanical properties of laminated composites. Also, machine learning is a sub-category of artificial intelligence, that refers to the process by which computers develop the ability to continuously learn from and make predictions based on data, then make adjustments without further programming. In the present study, the tapered box beam type PIC robot arm for carrying and transferring wide and thin LCD display was designed based on the machine learning in order to increase structural stiffness. Essential training data were collected from the reference elements, which were intentionally designated elements among finite element models, during preliminary FE analysis. Additionally, triaxiality values for each finite element were obtained for judging the dominant external loading type, such as tensile, compressive or shear. Training and evaluating machine learning model were conducted using the training data and loading types of elements were predicted in case the level accuracy was fulfilled. Three types of stacking sequences, which were to be known as robust toward specific loading types, were mosaically assigned to the PIC robot arm. Henceforth, the bending type FE analysis was carried out and its result claimed that the PIC robot arm showed increased stiffness compared to conventional uni-stacking sequence type composite robot arm.