• Proceeding of EDISON Challenge
• /
• 2017.03a
• /
• pp.304-310
• /
• 2017

In this paper, various webs of I-shaped beam used in aircraft spars are examined. Under the assumption that an aircraft spar is a cantilevered beam with a constant cross-section and is subjected to only bending, four kinds of webs are analyzed for three different sizes. To enable comparison, each hole has the same area and are subjected to the same load by using EDISON 2D Continuum analysis. While circular hole is the most often used, elliptic one is obtained with the minimum von-Mises stress by about 40% decreased. To verify the results gathered by EDISON, comparison was made with ANSYS and analytic predictions obtained with the stress intensity factor K. As comparison shows insignificant discrepancies, it is concluded that a well-designed beam with elliptic holes will be the most efficient spar regarding weight to rigidity ratio in terms of the bending stress.

• Journal of Energy Engineering
• /
• v.24 no.4
• /
• pp.55-62
• /
• 2015

It is expected that the size of welding defect affects the mechanical performance of welded medium density polyethylene (MDPE) pipe joints. In this study, butt fusion welded MDPE pipe joints with a single spherical or planar defect of various sizes were studied using experimental crush testing and also by finite element method. The crush test showed that the mechanical performance of crush was not affected by the size and geometry of a single welding defect when the defect size was increased to 45% of the pipe's wall thickness. The simulation results indicated that the effect of the single welding defect on the Von Mises stress distribution near the defect explained the reason of the test results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.3
• /
• pp.353-358
• /
• 1995

The emission characteristics of a semi-Bunsen type burner for gas boilers were studied experimentally. The experimental results reveal that nitric oxide emission increases with fuel flow rate. It is linearly proportional to total fue flow rate at a small amount of fuel up to 0.4 liters per minute. It does not change significantly within the range of fuel flow rate from 0.4 to 1.2 liters per minute per nozzle and increases at large fuel flow rate. The carbon monoxide emission reveals to be dependent upon the fuel flow rate per each nozzle and the number of fuel injection nozzles. Diameter of an injection nozzle could have an effect on the emission characteristics of this type of burners. However, there is no marked change in the nitric oxide emission if the total fuel flow rate is same with different nozzle sizes.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2002.10a
• /
• pp.533-540
• /
• 2002

Tubular joints having a large diameter are reinforced using internal ring stiffener in order to increase the load carrying capacity. In this study, the static strengths of Internally ring-stiffened tubular T-joints subjected to compressive brace loading are assessed. Nonlinear finite element analyses are used to compute the behavior of unstiffened and ring-stiffened T-joints. From the numerical results, Internal ring stiffener is found to efficient in improving the ultimate capacity, and reinforcement effect are calculated. The influence of geometric parameters for members and ring is evaluated. Based on the FE results, regression analysis is performed considering practical sizes of ring stiffener, finally strength estimation formulae for ring-stiffened T-joints are proposed.

• Journal of the Korea Society for Simulation
• /
• v.9 no.2
• /
• pp.1-14
• /
• 2000

Recently, as construction of information infra including high-speed communication networks remarkably expands, more various information services have been provided. Thus the number of internet users rapidly increases, and it results in heavy load on Web server and higher traffics on networks. The phenomena cause longer response time that means worse quality of service. To solve such problems, much effort has been attempted to loosen bottleneck on Web server, reduce traffic on networks and shorten response times by caching informations being accessed more frequently at the proxy server that is located near to clients. And it is also possible to improve internet performance further by allowing clients to share informations stored in proxy caches. In this paper, we perform simulations of hierarchical proxy caches with the 3-level 4-ary tree structure by using real web traces, and analyze cache hit ratio for various cache replacement policies and cache sizes when the delayed-store scheme is applied. According to simulation results, the delayed-store scheme increases the remote cache hit ratio, that improves quality of service by shortening the service response time.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.10
• /
• pp.1014-1020
• /
• 2011

This presents a motion and force estimation system of human fingers by using an Electromyography (EMG) sensor module and a data glove system to be proposed in this paper. Both EMG sensor module and data glove system are developed in such a way to minimize the number of hardware filters in acquiring the signals as well as to reduce their sizes for the wearable. Since the onset of EMG precedes the onset of actual finger movement by dozens to hundreds milliseconds, we show that it is possible to predict the pattern of finger movement before actual movement by using the suggested system. Also, we are to suggest how to estimate the grasping force of hand based on the relationship between RMS taken EMG signal and the applied load. Finally we show the effectiveness of the suggested estimation system through several experiments.

• Computers and Concrete
• /
• v.15 no.4
• /
• pp.673-686
• /
• 2015

R-curve based on the size effect law previously developed for geometrically similar specimens (geometry type III) is extended to geometries with variable depth (geometry type I) as well as with variable notch (geometry type II), where the R-curve is defined as the envelope of the family of critical strain energy release rates from specimens of different sizes. The results show that the extended R-curve for type I tends to be the same for different specimen configurations, while it is greatly dependent on specimen geometry in terms of the initial crack length. Furthermore, the predicted load-deflection responses from the suggested R-curve are found to agree well with the testing results on concrete and rock materials. Besides, maximum loads for type II specimen are predicted well from the extended R-curve.

• Structural Engineering and Mechanics
• /
• v.39 no.1
• /
• pp.115-123
• /
• 2011

The present work deals with obtaining the critical buckling load and the natural frequencies of clamped, orthotropic, rectangular thin plates subjected to different linear distributed in-plane forces. An analytical solution is proposed. Using the Ritz method, the dependence between in-plane forces and natural frequencies are estimated for various plate sizes, and some results are compared with finite element solutions and where possible, comparison is made with previously published results. Beam functions are used as admissible functions in the Ritz method.

• Proceedings of the KIEE Conference
• /
• 2003.07d
• /
• pp.2480-2482
• /
• 2003

As make a simulator including user interface functions like start & stop, load parameters, record and save, view 3D display has a real-like length and numerical value of sizes, represent real-shape of inner and outer part of robot, make the possible fast and slow selective observation as a adjust a step, receiving the images through the image device which attached in robot, so make a motion tester simulator of humanoid robot which coded by windows based GUI(Graphic User Interface) program with a MMI(Man Machine Interface) function that user can watch the environment which included robot and use a images. For implement this, we use a design data that converted data which made by use a CAD for Laser RP(Rapid Prototyping) progress into C coding for simulator programming. Using OpenGL, an API of graphic, it has a efficiency and detail of graphic operation. To make and test animation data, it has the option of save and resume in animation.

• Journal of the Korean Society of Combustion
• /
• v.16 no.2
• /
• pp.16-22
• /
• 2011

It is a challenging task to apply large detailed chemical mechanisms of fuel oxidation in simulation of complex combustion phenomena. There exist a few systematic methodologies to reduce detailed chemical mechanisms to smaller sizes involving less computational load. This research work concerns generation of a skeletal chemical mechanism by a directed relation graph with specified accuracy requirement. Two sequential stages for mechanism reduction are followed in a perfectly stirred reactor(PSR) for high temperature chemistry and to consider the autoignition delay time for low and high temperature chemistry. Reduction was performed for the detailed chemical mechanism of n-heptane consisting of 561 species and 2539 elementary reaction steps. Validation results show acceptable agreement for the autoignition delay time and the PSR calculation in wide parametric ranges of pressure, temperature and equivalence ratio.