• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.3 s.234
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• pp.387-394
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• 2005

Accurate predictions and simulations of the behavior of space structures based on analytical models become more important. In order to perform analysis to support the design of Ku-band transponder panel for the Communications and Broadcasting Satellite(CBS), mathematical models of the panel were generated in the form of finite element models. Test verification of these models is required before the transponder panel can be certified for launch environments. A modal identification was performed to obtain modal parameters which can be compared with the test results using correlation techniques. This paper approaches the sensor placement from the standpoint of the structural dynamicist who uses the modal parameter obtained during launch environmental test. The models were validated by performing a test-analysis correlation and updating analysis. It was proved that the Ku-band transponder panel satisfies the environmental test requirements.

• Journal of KSNVE
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• v.9 no.1
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• pp.60-69
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• 1999

In the first paper of this research$^{(1)}$. a new time series method. directional ARMAX (dARMAX) model-based approach. was proposed for rotordynamics identification. The dARMAX processes complex-valued signals, utilizing the complex modal testing theory which enables the separation of the backward and forward modes in the two-sided frequency domain and makes effective modal parameter identification possible. to account for the dynamic characteristics inherent in rotating machinery. In this second part. an evaluation of its performance characteristics based on both simulated and experimental data is presented. Numerical simulations are carried out to show that the method. a complex time series method. successfully implements the complex modal testing in the time domain. and it is superior in nature to the conventional ARMAX and the frequency-domain methods in the estimation of the modal parameters for isotropic and weakly anisotropic rotor systems. Experiments are carried out to demonstrate the applicability and the effectiveness of the dARMAX model-based approach, following the proposed fitting strategy. for the rotordynamics identification.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.711-719
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• 2006

The effluent from anaerobic digestion process of slurry-type piggery waste has a characteristic of very low C/N ratio. Because of high nitrogen content, it is necessary to evaluate nitrogen removal alternative rather than conventional nitrification-denitrification scheme. In this study, two parallel treatment schemes of SBR-like partial nitritation reactor coupled with anaerobic ammonium oxidation (ANAMMOX) reactor, and a nitritation reactor followed by nitrite denitrification process were evaluated with a slurry-type piggery waste. The feed to reactors adjusted with various $NH_4-N$ and organics concentration. The nitrite accumulation was successfully accomplished at the loading rate of about $1.0kgNH_4-N/m^3-day$. The $NO_2-N/NH_4-N$ ratio 1~2.6 in nitritated effluent that operated at HRT of 1 day indicated that SBR-like partial nitritation was applicable to ANAMMOX operation. Meanwhile, the nitrite accumulation of 87% was achieved at SBR operated with HRT of 3 days and $0.4mgO_2/L$ for denitritation. Experimental results further suggested that HRT (SRT) and free ammonia(FA) rather than DO are an effective control parameter for nitrite accumulation in piggery waste.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.2
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• pp.15-21
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• 2012

Purpose : The purpose of this study is to compare the rehabilitation effects of hydrotherapy and Bobath therapy. Methods : The study was performed with patients of hemiparesis caused by cerebral stroke. The participants were divided into two groups based on random sampling method. One group received hydrotherapy while the other received Bobath therapy. Each rehabilitation program lasted 40 minutes a day, 5 days a week, for 6 weeks. Pertinent indicators-Berg's balance scale (BBS), gait parameter, and static balance analysis-were recorded before andafter the programs, as well as every 2 weeks during the rehabilitation programs Results : There was showed a significantly increase of BBS score. Static open and close showed statistically significant in interaction by time and groups. There was significant differences of gait velocity. Conclusion : These findings in this study that the hydrotherapy was effective therapy in improving balance and gait velocity.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.2
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• pp.20-30
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• 2001

In the paper, we propose a predictive control scheme using multiple neural network-based prediction models. To construct the multiple models, we select several specific values of a parameter whose variation affects serious control performance in the plant. Among the multiple prediction models, we choose one that shows the best predictions for future outputs of the plant by a switching technique. Based on a nonlinear programming method, we calculate the current process input in the nonlinear predictive control system with multiple prediction models. The proposed control method is shown to be very effective when a parameter of the plant changes or the time delay, if it exists, varies. It is also shown that the proposed method is successfully applied for the control of suspension in a electro-magnetic levitation system.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.268-273
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• 2000

Velocity-dependent increase in tonic stretch reflexes is one of the prominent characteristics of spasticity. It is very important to evaluate spasticity objectively and quantitatively before and after treatment for physicians. An accurate quantitative biomechanical evaluation for the spasticity which is caused by the disorder of central nervous system is made in this study. A sudden leg dropper which is designed to generate objective testing environment at every trial gives very effective environment for the test. Kinematic data are archived by the 3-dimensional motion analysis system($Elite^{(R)}$, B.T.S., Italy). Kinematic data are angle and angular velocity of lower limb joints, and length and lengthening velocity of lower limb muscle. A program is also developed to analyze the kinematic data of lower limb, contraction and relaxation length of muscles, and dynamic EMG data at the same tim. To evaluate spasticity quantitatively, total 31 parameters extracted from goniogram, EMG and muscle model are analyzed. Statistical analysis are made for bilateral correlations for all parameters. The described instrumentation and parameters to make quantitative and objective evaluation of spasticity shows good results.

• Steel and Composite Structures
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• v.26 no.6
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• pp.663-672
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• 2018

This paper contains a consistent couple-stress theory to capture size effects in Euler-Bernoulli nano-beams made of three-directional functionally graded materials (TDFGMs). These models can degenerate into the classical models if the material length scale parameter is taken to be zero. In this theory, the couple-stress tensor is skew-symmetric and energy conjugate to the skew-symmetric part of the rotation gradients as the curvature tensor. The material properties except Poisson's ratio are assumed to be graded in all three axial, thickness and width directions, which it can vary according to an arbitrary function. The governing equations are obtained using the concept of minimum potential energy. Generalized differential quadrature method (GDQM) is used to solve the governing equations for various boundary conditions to obtain the natural frequencies of TDFG nano-beam. At the end, some numerical results are performed to investigate some effective parameter on buckling load. In this theory the couple-stress tensor is skew-symmetric and energy conjugate to the skew-symmetric part of the rotation gradients as the curvature tensor.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.365-371
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• 2000

To restore image degraded by out-of-focus blur and additive noise, an iterative restoration is used. Acceleration parameter is usually applied equally to all over the image without considering the local characteristics of degraded images. As a result, the conventional methods are not effective in restoring severely degraded edge region and shows slow convergence rate. To solve this problem we propose an adaptive iterative restoration according to local degradation, in which the acceleration parameter has low value in flat region that is less degraded and high value in edge region that is more degraded. Through experiments, we verified that the proposed method showed better results with fast convergence rate, showed Visually better image in edge region and lower MSE than the conventional methods.

• Journal of Power System Engineering
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• v.6 no.2
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• pp.40-47
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• 2002

In this paper, friction welding optimization for 1Cr0.5Mo-STS304 (${\phi}14\;mm$), AE applications for the weld quality evaluation and the applications of various life prediction methods such as LMP (Larson-Miller Parameter) and ISM (initial strain method) were investigated : The creep behaviors of those steels and the friction welded joints under static load were examined by ISM combined with LMP at 400, 500, 550 and $600^{\circ}C$, and the relationship between these two kinds of phenomena was studied. The real-time predicting equations of elevated-temperature creep life (rupture time) under any creep stress at any elevated-temperature could be developed by LMP and LMP-ISM. It was confirmed that the life prediction equations by LMP and LMP-ISM are effective only up to 102 h and can not be used for long times of 103-106 h, but by ISM it can be used for long times creep prediction of more than 104 h with most reliability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.124-129
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• 2011

An improved NDIF method is introduced to efficiently extract eigenvalues of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, membranes, and plates, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods (FEM and BEM). However, the NDIF method has the weak point that the system matrix of the NDIF method depends on the frequency parameter and, as a result, a final system equation doesn't take the form of an algebra eigenvalue problem. The system matrix of the improved NDIF method developed in the paper is independent of the frequency parameter and eigenvalues can be efficiently obtained by solving a typical algebraic eigenvalue problem. Finally, the validity and accuracy of the proposed method is verified in two case studies, which indicate that eigenvalues and mode shapes obtained by the proposed method are very accurate compared to the exact method, the NDIF method or FEM(ANSYS).