• Structural Engineering and Mechanics
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• v.56 no.6
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• pp.1003-1020
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• 2015

In this study, free vibration analysis of an edge cracked multilayered symmetric sandwich beams made of functionally graded materials are investigated. Modelling of the cracked structure is based on the linear elastic fracture mechanics theory. Material properties of the functionally graded beams change in the thickness direction according to the power and exponential laws. To represent functionally graded symmetric sandwich beams more realistic, fifty layered beam is considered. Composition of each layer is different although each layer is isotropic and homogeneous. The considered problem is carried out within the Timoshenko first order shear deformation beam theory by using finite element method. A MATLAB code developed to calculate natural frequencies for clamped and simply supported conditions. The obtained results are compared with published studies and excellent agreement is observed. In the study, the effects of crack location, depth of the crack, power law index and slenderness ratio on the natural frequencies are investigated.

• Structural Engineering and Mechanics
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• v.32 no.2
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• pp.269-282
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• 2009

Responding to the threat of terrorist attacks around the world, numerous studies have been conducted to search for new methods of vulnerability assessment and protective technologies for critical infrastructure under extreme bomb blasts or high velocity impacts. In this paper, a two-dimensional behavioral rate dependent lattice model (RDLM) capable of analyzing reinforced concrete members subjected to blast and impact loading is presented. The model inherently takes into account several major influencing factors: the progressive cracking of concrete in tension, the inelastic response in compression, the yielding of reinforcing steel, and strain rate sensitivity of both concrete and steel. A computer code using the explicit algorithm was developed based on the proposed lattice model. The explicit code along with the proposed numerical model was validated using experimental test results from the Woomera blast trial.

• Journal of the Semiconductor & Display Technology
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• v.10 no.3
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• pp.61-65
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• 2011

The capabilities of finite elements codes allow now accurate simulations of blanking processes when appropriate materials modelling are used. Over the last decade, numerous numerical studies have focused on the influence of process parameters such as punch-die clearance, tools geometry and friction on blanking force and blank profile. In this study, three dimensional finite element analysis is carried out to design a lead frame blanking die using LS-Dyna3D package. After design of the blanking die, an experiment is also carried out to investigate the characteristics of blanking for nickel alloy Alloy42, a kind of IC lead frame material. In this paper, it has been researched the investigation to examine the influence of process parameters such as clearance and air cylinder pressure on the accuracy of sheared plane. Through the experiment results, it is shown that the quality of sheared plane is less affected by clearance and air cylinder pressure.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.12
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• pp.1034-1039
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• 2016

This paper presents the implementation and control of a small-scaled excavator system. The commercial miniature of an excavator system has been modified and its control hardware is embedded to access the feedback control. Encoder sensors are attached to the joint and a force sensor is mounted on the end-effector so that feedback position control is accessible as well as force control. The dynamic model of the excavator system is derived as a four linkage robot arm and its control performances are simulated. Experimental studies of contact force control tasks are conducted to test the control algorithm for the excavator system.

• Journal of Korean Society of Archives and Records Management
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• v.11 no.1
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• pp.161-181
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• 2011

The study identifies benefits arising from the digital preservation of research data. Through analysing studies on digital preservation and digital research data in a economic perspective, broad benefits from digital preservation of research data have been identified and analysed quantitatively as well as qualitatively. It provides the starting point of systematic management and preservation of digital research data. Furthermore, it attempts modelling for investigating and producing benefits both in quantity and quality that is fundamental to promote investments.

• Proceedings of the KSPS conference
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• 2005.11a
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• pp.17-20
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• 2005

The purpose of this project is to develop a device that can automatically measure pronunciation of English speech produced by Korean learners of English. Pronunciation proficiency will be measured largely in two areas; suprasegmental and segmental areas. In suprasegmental area, intonation and word stress will be traced and compared with those of native speakers by way of statistical methods using tilt parameters. Durations of phones are also examined to measure speakers' naturalness of their pronunciations. In doing so, statistical duration modelling from a large speech database using CART will be considered. For segmental measurement of pronunciation, acoustic probability of a phone, which is a byproduct when doing the forced alignment, will be a basis of scoring pronunciation accuracy of a phone. The final score will be a feedback to the learners to improve their pronunciation.

• 대한예방의학회:학술대회논문집
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• 1998.10b
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• pp.72-73
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• 1998

• Earthquakes and Structures
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• v.1 no.2
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• pp.177-195
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• 2010

This paper presents an appraisal of four nonlinear static procedures (CSM, N2, MPA and ACSM) employed in seismic assessment of plan-irregular buildings. It uses a three storey reinforced concrete plan-irregular frame building exemplifying typical older constructions of the Mediterranean region in the early 1970s that was tested in full-scale under bi-directional pseudo-dynamic loading condition at JRC, Ispra. The adequacy and efficiency of the simplified analytical modelling assumptions adopted were verified. In addition, the appropriate variants of code-prescribed NSPs (CSM and N2) to be considered for subsequent evaluation were established. Subsequent parametric studies revealed that all such NSPs predicted reasonably well both global and local responses, having the benchmark values been determined through nonlinear dynamic analyses using a suit of seven ground motions applied with four different orientations. The ACSM, however, predicted responses that matched slightly better the median dynamic results.

• Journal of Smart Tourism
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• v.1 no.2
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• pp.19-25
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• 2021

Before COVID-19, tourist destinations have experienced problems with congestion of both famous tourist attractions and public transportation. Over-tourism is not an issue at this time, but it is likely to rekindle after the COVID-19 pandemic ends. One method of mitigating over-tourism is to estimate tourist behavior using a tourist transition model and consequently adjust public transportation operations. In this study, we propose a construction method for a model of tourist transitions among tourist attractions based on tourist GPS trajectory data. We construct tourist transition models using actual trajectory data for tourists staying in the vicinity of Kyoto City. The results verify the model performance.

• Computers and Concrete
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• v.23 no.3
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• pp.217-233
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• 2019

This paper describes the numerical modelling of an interior slab-column connection to investigate the punching shear resistance of reinforced concrete (RC) slabs under fire conditions. Parameters of the study were the fire direction, flexural reinforcement ratio, load levels, shear reinforcement and compressive strength of concrete. Moreover, the efficiency of the insulating material, gypsum, in reducing the heat transferred to the slab was assessed. Validation studies were conducted comparing the simulation results to experiments from the literature and common codes of practice. Temperature dependencies of both concrete and reinforcing steel bars were considered in thermo-mechanical analyses. Results showed that there is a slight difference in temperature endurance of various models with respect to concrete with different compressive strengths. It was also concluded that compared to a slab without gypsum, 10-mm and 20-mm thick gypsum reduce the maximum heat transferred to the slab by 45.8% and 70%, respectively. Finally, it was observed that increasing the flexural reinforcement ratio changes the failure mode from flexural punching to brittle punching in most cases.