• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.35-41
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• 2010

In this study, a mode analysis of uncoupled system was discussed using FRF. The eigen-mode range of FRF analysis is consistent with conventional FFT in spectrum. Also, the numerical response of second order uncoupled system was obtained using the Runge-Kutta Gill method. The displacement, velocity and acceleration response were calculated after numerical analysis and its response was used for the calculation of FRF for uncoupled system. Using the separated and mixed response of 1st and 2nd mode in example, its FRF was analysed for the prediction of the uncoupled systems and its mode shape was calculated by solving the eigen problem.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1873-1881
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• 2014

This paper deals with the design of multi-machine power system stabilizers (PSSs) and Static var compensator (SVC) using Modified shuffled frog leaping algorithm (MSFLA). The effectiveness of the proposed scheme for optimal setting of the PSSs and SVC controllers has been attended. The PSSs and SVC controllers designing is converted to an optimization problem in which the speed deviations between generators are involved. In order to compare the capability of PSS and SVC, they are designed independently once, and in a coordinated mode once again. The proposed method is applied on a multi-machine power system under different operating conditions and disturbances to confirm the effectiveness of it. The results of tuned PSS controller based on MSFLA (MSFLAPSS) and tuned SVC controller based on MSFLA (MSFLA SVC) are compared with the Strength pareto evolutionary algorithm (SPEA) and Particle swarm optimization (PSO) based optimized PSS and SVC through some performance to reveal its strong performance.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.3
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• pp.111-116
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• 2013

Noise problem that occurs on the road is raising a lot of problems in the economic, social and environmental aspects. The objective of this paper is to propose ANC(active noise cancellation)-based road traffic noise reduction algorithm-model which can reduce noise by generating frequency opposed to noise sources to improve and complement the problem that existing physical form of a noise barrier. In this paper, we measured the noise characteristic from collection of two difference car noise also ANC simulation has been performed by using road traffic noises input. In order to compare the control performance, we performed noise reduction simulation of ANC by filtered-X LMS algorithm and delayed control signal injection. As a result of this simulation, we confirmed that convergence performance and noise decrease effect to the filtered-X LMS algorithm by inputting the road traffic noise.

• Advances in Computational Design
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• v.2 no.4
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• pp.273-281
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• 2017

In this work, a comparative study of multi-objective meta-heuristics (MOMHs) for optimum design of a walking tractor handlebar is conducted in order to reduce the structural mass and increase structural static and dynamic stiffness. The design problem has objective functions as maximising structural natural frequencies, minimising structural mass, bending deflection and torsional deflection with stress constraints. The problem is classified as a many-objective optimisation since there are more than three objectives. Design variables are structural shape and size. Several well established multi-objective optimisers are employed to solve the proposed many-objective optimisation problems of the walking tractor handlebar. The results are compared whereas optimum design solutions of the walking tractor handlebar are illustrated.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.2
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• pp.15-20
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• 1983

The nature and the sources of sound in cars is discussed in the light of many previous works, and the importance of the system resonances inside cars is suggested. An investigation of a 'boom' problem in a small size passenger car is described. It was established that the 'boom' frequencies coincided with engine firing frequency and also with several system resonances. To find out main transmission path of the noise to the car interior, various possible sources were eliminated from the investigation by means of simple modification to the vehicle. Data on the structural modes of the body, and the acoustic modes of the passenger compartment at various forcing cases were obtained to provide better understanding of the problem. It was found that the acoustic resonance responsible for the boom was controlled largely the bending motion of the floor. To investigate the effect of the structural modification to the acoustic response, center floor of the car was reinforced. a great reduction of the noise inside the car especially at the offending speed range, was achieved by this modification.

• Journal of Nutrition and Health
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• v.36 no.3
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• pp.298-305
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• 2003

The purpose of this study was to investigate the relationship between the eating habits and social behavior of preschool children. Six hundred twenty seven children ranging in age from 4 to 7 and their mothers were asked to complete a questionnaire assessing the children's eating habits and kindergarten teachers were asked to rate the social behavior of their preschool children. The eating habits of children positively correlated to those of their mothers, primarily in meal regularity, breakfast frequency, unbalanced meals, overeating, eating delivery food and food preferences. The results showed that 33% of preschool children always had unbalanced meals and 50% sometimes had them. Children who had ice cream, cake, carbonated drinks or cookies as snacks more often, tend to have meals irregularly because they favored sweets and were possibly induced to have unbalanced meals. Sixty five percent of the children were graded as good in terms of having healthy eating habits and had good social behavior. The results indicate that the eating habits of children are related to problem behavior, especially social withdrawal and anxiety. That is, children who have undesirable eating habits are likely to be anxious or socially withdrawn.

• Structural Engineering and Mechanics
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• v.19 no.1
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• pp.21-42
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• 2005

A method is presented to detect and assess the structural damage from changes in natural frequencies using Genetic Algorithm (GA). Using the natural frequencies of the structure, it is possible to formulate the inverse problem in optimization terms and then to utilize a solution procedure employing GA to assess the damages. The technique has been applied to a cantilever beam and a plane frame, each one with different damage scenario to study the efficiency of the developed algorithm. A laboratory tested data has been used to verify the proposed algorithm. The study indicates the potentiality of the developed code to solve a wide range of inverse identification problems in a systematic way. The outcomes show that this method can detect and estimate the amount of damages with satisfactory precision.

• Structural Engineering and Mechanics
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• v.34 no.3
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• pp.319-334
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• 2010

The dynamic response of a finite Bernoulli-Euler beam resting on a tensionless Pasternak foundation and subjected to a concentrated harmonic load is investigated in this study. This load may be applied at the center of the beam, or it may be offset from the center. Since the elastic foundation is assumed to be tensionless, the beam may lift off the foundation, resulting in contact and non-contact regions in the system. An analytical/numerical solution is obtained from the governing equations of the contact and non-contact regions to determine the coordinates of the lift-off points. Although there is no nonlinear term in the equations, the problem appears to be nonlinear since the contact regions are not known in advance. Due to that nonlinearity, the essentials of the problem (the coordinates of the lift-off points) are calculated numerically using the Newton-Raphson technique. The results, which represent the symmetric and asymmetric responses of the beam, are presented graphically in this work. They illustrate the effects of the forcing frequency and the beam length on the extent of the contact regions and displacements.

• Korean Management Science Review
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• v.29 no.3
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• pp.1-11
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• 2012

This paper considers a localization problem in time difference of arrival (TDOA)-based radio frequency identification (RFID) systems. To estimate the position of a target tag, this paper suggests three localization algorithms that use benchmark tags. The benchmark tags are the same type as the target tag, but either the locations or distance of the benchmark tags are known. Two algorithms use the benchmarks for auxiliary information to improve the estimation accuracy of the other localization algorithms such as least squared estimator (LSE). The other one utilizes the benchmarks as essential tags to estimate the location. Numerical tests show that the localization accuracy can be improved by using benchmark tags especially when an algorithm using the LSE is applied to the localization problem. Furthermore, this paper shows that our benchmark algorithm is valuable when the measurement noise is large.

• Journal of Korea Multimedia Society
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• v.14 no.12
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• pp.1549-1558
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• 2011

In this paper, we address the problem of bandwidth sharing among multiple primary users and multiple secondary users in a cognitive radio network. In cognitive radio networks, effective spectrum assignment for primary and secondary users is a challenge due to the available broad range of radio frequency spectrum as well as the requisition of harmonious coexistence of both users. To handle this problem, firstly, Bertrand game model is used to analyze a spectrum pricing in which multiple primary users emulate with each other to acquire maximal profit. After that, we employ Cournot game to model the spectrum sharing of secondary users to obtain optimal profit for each user also. Simulation results show that our scheme obtains optimal solution at Nash equilibrium.