• Computers and Concrete
• /
• v.18 no.5
• /
• pp.983-998
• /
• 2016

Structural optimization is one of the most important topics in structural engineering and has a wide range of applicability. Therefore, the main objective of the present study is to apply the Lagrange Multiplier Method (LMM) for minimum cost design of singly and doubly reinforced rectangular concrete beams. Concrete and steel material costs are used as objective cost function to be minimized in this study, and ultimate flexural strength of the beam is considered to be as the main constraint. The ultimate limit state method with partial material strength factors and equivalent concrete stress block is used to derive general relations for flexural strength of RC beam and empirical coefficients are taken from topic 9 of the Iranian National Building Regulation (INBR9). Optimum designs are obtained by using the LMM and are presented in closed form solutions. Graphical representation of solutions are presented and it is shown that proposed design curves can be used for minimum cost design of the beams without prior knowledge of optimization and without the need for iterative trials. The applicability of the proposed relations and curves are demonstrated through two real life examples of SRB and DRB design situations and it is shown that the minimum cost design is actually reached using proposed method.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.25 no.4
• /
• pp.47-57
• /
• 1988

A new discrete method using idealized rigid body-spring model is introduced. This rigid element method is known to be more efficient and accurate than the finite element method in the inelastic range of structural analysis owing to simplified stress-strain and strain-displacement relations This kind of physical concept using idealized rigid model has been already applied among structural engineers to some problems such as rigid-plastic analysis or plastic design considering rigid bodies and plastic hinges. However the most rigorous and systematic research has been recently performed by T. Kawai et al.[1]. In this paper, an attempt is made to analyze the collapse behavior of stiffened plates under lateral loading by some modification and expansion of Kawai's rigid element approach to the collapse of plates without stiffener. Stiffened plates are treated as orthotropic plates which have equivalent bending rigidities. By employing Morley's plate element resubdivision technique, variety is given to mesh-division styles which have greate effect on the accuracy of numerical results. Some examples are shown to verify the validity of applying rigid element method to the ultimate strength analysis of stiffened plates. It is clarified that lateral deflections and detailed collapse patterns up to the ultimate state of stiffened plates can be easily obtained by the present approach.

• Journal of the Korean Society for Railway
• /
• v.13 no.6
• /
• pp.577-582
• /
• 2010

The importance of maintenance of rail surface defects is increasing according to the KTX operation. That is because during high speed operation of rolling stocks, rail surface defects shorten fatigue life of rail, accelerate track degradation and deteriorate ride comfort. Rail grinding has been applied for effective rail maintenance in Kyeong-Bu HS line. This paper evaluates the effectiveness of rail grinding in term of rail fatigue life. To this end, the stresses of the rail are measured under KTX running and the equivalent stress range is calculated by RMC after the frequency analysis done with rainflow counting method. Also, The Modified Miner's rule is applied to predict the fatigue life of ground rail. The result of the analysis shows that the fatigue life of ground rail is increased by 15%.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.6
• /
• pp.1156-1162
• /
• 1992

The effect of aspect ratio on the flow characteristics of elliptic jets was experimentally investigated. The flow characteristics of sharp-edged elliptic nozzles with aspect ratio of 1 (round nozzle), 2 and 4 were measured by using a 3-D LDV system along the major and minor axis at X/De = 2, 3, 5, 7 and along the centerline up to X/De = 14. At each measurement point mean velocites, turbulent intensities, skewness of three orthogonal velocity components, and Reynolds shear stress were obtained. The Reynolds number based on the nozzle exit velocity and nozzle equivalent diameter(De) was about 4 * 10$^{4}$. Difference in the spreading rate along the major and minor axis was remarkable. The jet half width along the major axis decreased at first and then increased again with going downstream. But the jet width along the minor axis increased steadly. The elliptic jet of AR = 2 had two switching points within the measurement range, while that of AR = 4 had only one. (AAA) : The elliptic jet of AR = 2 showed larger velocity decay rate than that of AR = 1 and AR = 4. The effect of aspect ratio on the flow characteristics of elliptic jets was dominant in the near jet regions of X/De < 7, and the skewness and Reynolds shear stress had quite different distribution depending on the aspect ratio of the elliptic nozzle.

• Biomaterials and Biomechanics in Bioengineering
• /
• v.3 no.2
• /
• pp.115-127
• /
• 2016

Shoulder pain, injury and discomfort are public health and economic issues world-wide. The function of these joints and the stresses developed during their movement is a major concern to the orthopedic surgeon to study precisely the injury mechanisms and thereby analyze the post-operative progress of the injury. Shoulder is one of the most critical joints in the human anatomy with maximum degrees of freedom. It mainly consists of the clavicle, scapula and humerus; the articulations linking them; and the muscles that move them. In order to understand the behavior of individual muscle during abduction arm movement, an attempt has been made to analyze the stresses developed in the shoulder muscles during abduction arm movement during the full range of motion by using the 3D FEM model. 3D scanning (ATOS III scanner) is used for the 3D shoulder joint cad model generation in CATIA V5. Muscles are added and then exported to the ANSYS APDL solver for stress analysis. Sensitivity Analysis is done for stress and strain behavior amongst different shoulder muscles; deltoid, supraspinatus, teres minor, infraspinatus, and subscapularies during adduction arm movement. During the individual deltoid muscle analysis, the von Mises stresses induced in deltoid muscle was maximum (4.2175 MPa) and in group muscle analysis it was (2.4127MPa) compared to other individual four rotor cuff muscles. The study confirmed that deltoid muscle is more sensitive muscle for the abduction arm movement during individual and group muscle analysis. The present work provides in depth information to the researchers and orthopedicians for the better understanding about the shoulder mechanism and the most stressed muscle during the abduction arm movement at different ROM. So during rehabilitation, the orthopedicians should focus on strengthening the deltoid muscles at earliest.

• Journal of Plant Biotechnology
• /
• v.41 no.4
• /
• pp.206-211
• /
• 2014

Nutritional assessment of transgenic crops to improve safety evaluations is important for food production. An oxidative stress-tolerant rice was generated by stable insertion of the TC gene-a tocopherol cyclase isolated from tobacco-into the genome of a common variety of japonica colored rice. The nutritional composition of the brown rice grains from the transgenic TC line was compared with that of the parental rice cultivar Heugnambyeo and two different varieties of non-transgenic rice. The results indicate that the analyzed nutritional compositions of the brown grains from the transgenic TC line were within the range of values reported for other commercial lines, and measurements of nutritional compositions were equivalent to those of the non-transgenic rice.

• Computational Structural Engineering
• /
• v.7 no.3
• /
• pp.133-141
• /
• 1994

When a bolt is tightened up to the range of plastic deformation, yielding may be governed by the combined stresses due to the axial force developed in the bolt and the frictional torque induced on the thread by the contact with the nut. Consideration is taken account of the fact that the unengaged portion of the thread has least sectional area, being subject to initial yielding. Once yielding has taken place some strain hardening effect may result. Incremental stress-strain relations are used to treat the continued yielding, which is equivalent to treat continued yielding as if summing up the effects of thin walled cylinders subject to plastic deformation. M10 bolts of fine threads are used for both computational and experimental purposes. Variation of axial forces and frictional torques vs. the frictional coefficients are presented together with other plots showing some characterist of bolt under plastic deformation. Finally, a design and control aid for the tightening(i.e., kind of nomograph) is presented, showing the relationships among the torque factor and frictional coefficients for that particular bolt used in the experiment.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.33 no.3
• /
• pp.145-152
• /
• 2020

In this study, we evaluated spinal stability based on the change in the thoracolumbar fixation segment using finite element analysis (FEA). To accomplish this, a finite element (FE) model of a normal thoracolumbar spine (T10-L4), including intervertebral discs (IVD), ligaments, and facet joints, was constructed, and the material properties reported in previous studies were implemented. However, L1 was assumed as the lesion site, and three types of posterior fixation, namely, L1-L2, T12-L2, and T12-L1-L2, were implemented in the thoracolumbar FE model. In addition, the loading conditions for flexion, extension, lateral bending, and axial rotation were adopted. Through the series FEA, the deformation, equivalent stress, range of motion, and moment on the pedicle screws, vertebrae, and IVD were calculated, and the spinal stability was evaluated based on the FEA results.

• Horticultural Science & Technology
• /
• v.32 no.2
• /
• pp.227-234
• /
• 2014

The responses to chilling temperature of 12 Korean cucumber varieties was compared to those of two U.S.A. (previously determined cold tolerant NC76 and 'Chipper'), and Chinese and Japanese germplasms. Seedlings of each entry were exposed to $4^{\circ}C$ (Experiment 1) and $1^{\circ}C$ (Experiments 2 and 3) at the first-true leaf stage for eight and nine hours, respectively, under 80% relative humidity (RH) and $149{\mu}moles{\cdot}m^{-2}{\cdot}s^{-1}$ photosynthetic photon flux (PPF). The chilling response [damage rating (DR)] of each accession was based on visual ratings (1 to 5) after treatment, where 1 = no damage, 2 = slight, 3 = moderate, 4 = advanced, and 5 = severe damage. Predictably the cumulative average DR of chilling tolerant line NC76 and 'Chipper' after chilling w as 1 and 1.1, respectively. Korean 'Nacdongchungjang' was most sensitive to chilling temperatures [DR = 2.3] when compared to the other entries examined. The sensitivity to chilling of 'Nacdongchungjang' was followed by Chinese 'Dongguan' [DR = 1.7]. In contrast, 'Saeronchungjang' (DR = 1) and 'Janghyungnachap' (DR = 1) were the most chilling tolerant of the Korean accessions examined and equivalent to the response of line NC76 and 'Chipper'. Nevertheless, chloroplast type genotyping of these accessions with known chilling-linked sdCAPS genomic markers revealed genotypic differences between chilling tolerant lines (NC76 and 'Chipper') and all Korean lines examined.

• Resources Recycling
• /
• v.9 no.3
• /
• pp.46-53
• /
• 2000

Recently, the efficient disposal of the waste rubber is necessary due to increasing amount of the waste rubbers. In this paper, method of recycling waste rubbers as components of medium for hydroponic rose culture was suggested. We investigated growth of rose, and macro- and micro-elements, pH and EC of the media amended with waste rubber, In the beginning of culture, stress symptoms such as thin brittle stem and incipient wilting were observed, but they disappeared in a few weeks. Concentration of $Zn^{2+}$ in media at flowering increased in proportion to contents of waste tire in the media. pH of media at flowering were in the range of 5.70 to 6.35. Rose growth in all media, except in wasterock wool mixed with EPDM powder at 9:3 ratio, was normal and equivalent to the control in terms of stem length, number of stems harvested and fresh weight.