• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.969-975
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• 2013

While accelerating, bicycle frames are subject to torsion forces and deformation. In this study, bicycle frame durability was evaluated by using structural, fatigue, and vibration experiments. Three types of models were designed by changing the frame configurations according to the shape and direction of a bicycle frame design. Because maximum equivalent stress was greatest at the saddle and at connected parts in Models 1, 2, and 3, these frame sections were most vulnerable to failure. Model 2 was the least safe, due to the increased total deformation and equivalent stresses in the top tube horizontal to the ground. Based on vibration and fatigue analysis results, Model 2 was also determined to be the least safe frame, because the head tube was placed slightly higher above the seat tube and inclined to $10^{\circ}$. These study results can be utilized in the design of bicycle frames by investigating prevention and durability against damage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.843-850
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• 2010

A spacer grid assembly is one of the most important structural components of the nuclear fuel assembly of a Pressurized Water Reactor (PWR). A primary design requirement is that the fuel rod integrity be maintained by the spacer grid assembly during the operation of the reactor. In this study, we suggested a new spacer grid assembly having a fuel rod support, which is capable of sliding when the fuel rod vibrates due to flow-induced vibrations in the reactor. By adjusting the relative displacement between the fuel rod and its support, the proposed design will help in reducing fuel rod fretting damage.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.33-39
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• 2007

In this paper, we investigate the throughput capacity of a multi-hop relay with cognitive radio (CR) enabled relay stations (RS). We suggest a TDMA/FDMA based frame structure where RSs dynamically select unused channels to communicate with the base station (BS) using CR techniques to analyze the throughput capacity. We develop the throughput capacity model for the proposed system based on utilization factor. The analytical results based on those equations show significant improvement in throughput capacity for CR enabled multi-hop relay system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.298-303
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• 2016

Owing to the advantages of reduced weight and wind effect, the space-framed towers that consist of vertical and horizontal members of circular hollow tubular sections have been adopted widely for various purposes. It is critical to guarantee the strengths of tubular joints where vertical and horizontal members are connected structurally to make the entire space-framed system behave as a single tower structure. In this study, a strength evaluation was conducted for T-type tubular joints subjected to the concurrent action of compression and bending. Three of the available design codes, i.e., AISC, Eurocode 3, ISO 19902 were investigated and a design equation was suggested for an ultimate strength interaction between the axial force and bending moment based on nonlinear finite element analyses by selecting the slenderness ratios at the joints as major parameters.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.267-275
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• 2014

Recently, the construction of curved bridge has increased, thus researchers perform the analytic studies on PSC curved bridge. However, the grid analysis method that are mostly used in the construction industry is not adequate to acquire the precise behavior evaluation of curved PSC briges. Therefore, the precise finite element analysis considering the effective variables were performed to establish the basis for the design method of curved PSC bridge by using 3D elements and bar element. The evaluated variables in this analysis were the number of girders, loading point, section figure, change of prestressing force. The results show the load carrying capacity of the 3 girder type bridge is 200% of that of the 2 girder type, and that applying load on outer girder makes the load resistance capacity and the deflection deviation of 2 girders smaller. The structural capacity of the bridge is improved when the section size is increased, but the efficiency of it is not sufficient enough compare to that of the change of prestressing forces. The change of prestressing forces shows that the camber and the load carrying capacity are linearly increased as PS force is increased. Moreover, when the PS force applied on outer girder is increased than that of inner girder, the deviation of deflection the girders decreases, thereby the stability of the bridge is enhanced.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.1
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• pp.43-50
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• 2001

In order to analyze the dynamic motions of fish cage systems made of a frame and a netting under the conditions of waves and current, the hydraulic model experiment at towing tank and the numerical computation using boundary integral element method based on linear potential theory were carried out on a square and a circular type of fish cage, The computed and measured results for the dynamic motions of model fish cage systems showed that the heave and pitch motions were almost unaffected by the inclusion of nets, while the surge motions were very reduced by drag force acting on them. In addition, irregular wave-induced motions of fish cages included non-negligible 2nd order harmonic components at high frequency nearly twice the wave frequency. The reason why these motions were considered was due to resonance or structural components of frames being overflown and out of water during a wave cycle. It was found that circular type was more desirable structure in the open sea than square one only in the respect of dynamic motions due to waves and current. Further verifications were needed considering hydrodynamic forces, fatigue life, and structure analysis based on long term stochastic waves including frequency and time domain for the purpose of analyzing and designing fish cage systems.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.477-483
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• 2013

The widlass base frame which is currently used is designed by lots of volume and costs so as to obtain high rigidity in spite of the greatly external load. The purpose of this research is to draw conceptual design of optimal design which can satisfy high rigidity existing windlass base frame has and lessening the body at the same time. Therefore, it progressed conceptual design by applying Topology optimization and Size optimization based on the finite-element analysis for the early model and indicated the result by comparing the early model with optimized model. As the result of Topology optimization, its stress was increased by about 6MPa and weight was decreased by about 560kg in comparison with the early model. In addition, in case of Size optimization, its stress was increased by about 7MPa and weight was decreased by about 1,560kg in comparison with the early model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.577-585
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• 2023

Lateral torsional buckling causessafety accidentssuch as collapse accidents during erection. Therefore, anaccurate safety designshould be conducted. Lateral torsional buckling canbe prevented by reinforcing the end orreducing the unbraced length. The method ofreducing the unbraced length by installing a crossframe has high material and installation costs and low maintenance performance.In addition, structuralsafety may be deteriorated due to cracks. The end reinforcement method using Concrete Filled Half Pipe Stiffeneris a method ofreinforcing the end of a plate girder using a stiffenerin the form of a semi-circular column. This method increasesthewarping strength ofthe girder and increasesthe lateral torsional buckling strength.In thisstudy, the effect ofincreasing the warping strengthof plate girders with concrete filled half pipe stiffeners was confirmed. To verify the effect, the results ofthe designequationand the finite element analysis were compared and verified through a experiment. As a result, the plate girderwithCFHPS increased thewarping strengthand confirmed that the lateral torsional buckling strength was increased.

• Composites Research
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• v.31 no.5
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• pp.227-237
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• 2018

In this paper, the design application for the lightweight and insulation of the manipulator of the mobile welding robot for the closed/narrow space is presented. A variety of robotic platforms have been developed for weld-worker using a welding robot outside a workpiece for welding work in a complex and narrow space such as a ship or an offshore plant. Normally, The development process of robots consists of machine development, electronic device development, control algorithm development and integration verification considering application environment and requirements. In order to develop the robustness of the welding robot, the lightweight design of the robot manipulator considering the environmental conditions was performed in the basic design of the robot platform. Also, The results of the robot selection and validation, analysis and testing for the insulation performance and cooling performance and the results of the research are shown.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.251-258
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• 2014

The purpose of the neural image analysis is to trace the velocities and the directions of moving mitochondria migrating through axons. This paper proposes an automated technique for detecting axon structure. Previously, the detection process has been carried out using a partially automated technique combined with some human intervention. In our algorithm, a consolidated image is built by taking the maximum intensity value on the all image frames at each pixel Axon detection is performed through vessel enhancement filtering followed by a peak detection procedure. In order to remove errors contained in ridge points, a filtering process is devised using a local reliability measure. Experiments have been performed using real neural image sequences and ground truth data extracted manually. It has been turned out that the proposed algorithm results in high detection rate and precision.