• Advances in Automotive Engineering
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• v.1 no.1
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• pp.123-141
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• 2018

Hardware-in-the-loop (HiL) simulation is a very powerful tool to design, test and verify automotive control systems. However, well-validated and high degree of freedom vehicle models have to be utilized in these simulations in order to obtain realistic results. In this paper, a vehicle dynamics model developed in the Carsim Real Time program environment and its validation has been performed using experimental results. The developed Carsim real time model has been employed in the Tofas R&D hardware-in-the-loop simulator. Experimental and hardware-in-the-loop simulation results have been compared for the standard FMVSS No. 126 test and the results have been found to be in good agreement with each other. Two electronic stability control (ESC) algorithms, named the Basic ESC and the Integrated ESC, taken from the earlier work of the authors have been tested and evaluated in the hardware-in-the-loop simulator. Different evaluation methods have been formulated and used to compare these ESC algorithms. As a result, the Integrated ESC system has been shown superior performance as compared to the Basic ESC algorithm.

• Earthquakes and Structures
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• v.18 no.1
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• pp.45-56
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• 2020

The application of critical excitation method with displacement-based objective function for multi degree of freedom (MDOF) systems is investigated. To this end, a new critical excitation method is developed to find the critical input motion of a MDOF system as a synthetic accelerogram. The upper bound of earthquake input energy per unit mass is considered as a new constraint for the problem, and its advantages are discussed. Considering this constraint, the critical excitation method is then used to generate synthetic accelerograms for MDOF models corresponding to three shear buildings of 10, 16, and 22 stories. In order to demonstrate the reliability of generated accelerograms to estimate dynamic response of the structures, three target ground motions with considerable level of energy contents are selected to represent "real critical excitation" of each model, and the method is used to re-generate these ground motions. Afterwards, linear dynamic analyses are conducted using these accelerograms along with the generated critical excitations, to investigate the key parameters of response including maximum displacement, maximum interstory drift, and maximum absolute acceleration of stories. The results show that the generated critical excitations can make an acceptable estimate of the structural behavior compared to the target ground motions. Therefore, the method can be reliably implemented to generate critical excitation of the structure when real one is not available.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.803-807
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• 2009

The bobsleigh is a winter sport which use a sled to slide down an ice-covered course. There is a big expectation for having a training environment and being able to train year round. At present, training is very limited due to the season or course facilities. A variety of VR (Virtual Reality) equipment has been developed in recent years, and it is beginning to spread. We have also made our contribution in bobsleigh simulation. The reactive force applied in our bobsleigh simulation is much smaller than that of a real bobsleigh. This paper proposes a method to enhance reactive force of bobsleigh simulation in real time. The reactive force is magnified instantly in the physically-based simulation. The Laplacian filter is applied to the sequence of reactive force, this technique is often used in the field of image processing. The simulation is comprised of four large scale surround screens and a 6-D.O.F. (Degree Of Freedom) motion system. We also conducted an experiment with several motion patterns to evaluate the effectiveness of enhancement. The experimental results proved useful in some cases.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.5
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• pp.356-361
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• 2014

Accurate block shape assessment is critical for ship manufacturing and a careful assessment of the shape of a fabricated block against the design shape is a core issue. However, in current fabrication practice, the shape of each block is evaluated manually using rigid body transformation. This manual evaluation process entirely depends on workers' experiences and knowledge and makes automation of block shape assessment difficult. In this paper we propose a computation method on the registration for shape assessment of a block during the fabrication process and for evaluation of its completion against the design shape. A conversion on matching method by adding DOF(degree of freedom) restriction is required to reach the goals. We test our method using a real block quality assessment data to demonstrate its applicability to real ship manufacturing process.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.123-128
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• 2006

This paper presents the design of a surveillance night vision system for marine ships. Both a hardware system and software modules for tracking control are developed. In order to control each control axis with compensation for ship motion, the two-degree of freedom(TDF) PID controller is designed and its parameters are tuned using a real-coded genetic algorithm(RCGA). Simulation demonstrates the effectiveness of the proposed system.

• Earthquakes and Structures
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• v.16 no.4
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• pp.487-499
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• 2019

Energy-based seismic design of structures has gradually become prominent in today's structural engineering investigations because of being more rational and reliable when it is compared to traditional force-based and displacement-based methods. Energy-based approaches have widely taken place in many previous studies and investigations and undoubtedly, they are going to play more important role in future seismic design codes, too. This paper aims to compute the maximum earthquake energy input to elastic single-degree-of-freedom (SDOF) systems for selected real ground motion records. A data set containing 100 real ground motion records which have the same site soil profiles has been selected from Pacific Earthquake Research (PEER) database. Response time history (RTH) analyses have been conducted for elastic SDOF systems having a constant damping ratio and natural periods of 0.1 s to 3.0 s. Totally 3000 RTH analyses have been performed and the maximum mass normalized earthquake input energy values for all records have been computed. Previous researchers' approaches have been compared to the results of RTH analyses and an approach which considers the pseudo-spectral velocity with Arias Intensity has been proposed. Graphs of the maximum earthquake input energy versus the maximum pseudo-spectral velocity have been obtained. The results show that there is a good agreement between the maximum input energy demands of RTH analysis and the other approaches and the maximum earthquake input energy is a relatively stable response parameter to be used for further seismic design and evaluations.

• Journal of applied mathematics & informatics
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• v.42 no.2
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• pp.257-281
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• 2024

In real life, a decision-maker can assign multiple values for pairwise comparison with a certain confidence level. Studies incorporating multi-choice parameters in multi-criteria decision-making methods are lacking in the literature. So, In this work, an extension of the Best-Worst Method (BWM) with multi-choice pairwise comparisons and multi-choice confidence parameters has been proposed. This work incorporates an extension to the original BWM with multi-choice uncertainty and confidence level. The BWM presumes the Decision-Maker to be fully confident about preference criteria vectors best to others & others to worst. In the proposed work, we consider uncertainty by giving decision-makers freedom to have multiple choices for preference comparison and having a corresponding confidence degree for each choice. This adds one more parameter corresponding to the degree of confidence of each choice to the already existing MCDM, i.e. multi-choice BWM and yields acceptable results similar to other studies. Also, the consistency ratio remained low within the acceptable range. Two real-life case studies are presented to validate our study on proposed models.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.344-351
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• 2016

Recently, mobile application for english vocabulary learning is being developed actively. However, most mobile English vocabulary learning applications did not effectively connected with the technical advantages of mobile learning. Also,the study of mobile english vocabulary learning app are still insufficient. Therefore, this paper development a english vocabulary context-learning Agent that can practice context learning more reasonably using a location-based service, a character recognition technology and augmented reality technology based on smart phones. In order to evaluate the performance of the proposed agent, we have measured the precision and usability. As results of experiments, the precision of learning vocabulary is 89% and 'Match between system and the real world', 'User control and freedom', 'Recognition rather than recall', 'Aesthetic and minimalist design' appeared to be respectively 3.91, 3.80, 3.85, 4.01 in evaluation of usability. It were obtained significant results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.4
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• pp.232-237
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• 2015

Complex dynamic systems are composed of several subsystems. Each subsystems affect the dynamics of other subsystems since they are connected to each other in the whole system. Theoretically, we can derive the exact mass and stiffness matrix of a system if we have the natural frequencies and mode shapes of that system. In real situation, the modal parameters for the higher modes are not available and the number of degree of freedom concerned are not so high. This paper shows a simple method to derive the mass and stiffness matrix of a system considering the connecting points of subsystems. Since the accuracy of reconstructed structure depends on the selection of node and mode, the rule for selection of node and mode are derived from the numerical examples.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1845-1855
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• 2004

This paper presents the forward kinematics of the Casing Oscillator that is a construction machine. The Structure of the Casing Oscillator is similar to those of 4 degree-of-freedom mechanisms with a redundancy. With analytical (geometrical) methods, the solutions of the forward position kinematics problem are significantly found by both solving an 8$^{th}$ -order polynomial equation in one unknown variable and using one over-constraint geometrical equation which can be derived under the condition of a redundancy. The proposed forward kinematics has closed-form solutions and allows Auto-Balancing control of the moving platform in real time. Numerical examples are presented and the results are verified by an inverse kinematics analysis.