• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.395-400
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• 1994

High resolution spectral analysis is essential for ECG anaysis. The fast Fourier transform has been widely used for frequency analysis of ECG signals but this procedure provides poor resolution when the data record is short and shows Gibb's phenomena. The ARMA FTF (Fast Transversal Filter) algorithm is used for high resolution spectral analysis. The reason of unsalability of this algorithm is investigated and the method for improving the numerical stability is proposed. The proposed algorithm is applied to spectral analysis of the ECG. Since this result has less variations than the FFT based results, it can be used for the computerized diagonosis of the ECG.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.273-287
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• 2006

This study investigates the failure mechanism and load-carrying capacity of a single-shell lining which has no disturbance in transfer of shear force, with respect to a conventional double-shell lining which has separation between layers of shotcrete lining and secondary concrete lining by water-proof membrane. In order to evaluate the capacity, a 2-D numerical investigation is preliminarily carried out and then real-scale loading tests with tunnel lining section specimens are performed on the condition given by the numerical investigation. In the test, a concentrated load is applied for considering a released ground load or rock wedge load. Through this study, it appears that the single-shell lining takes the load-bearing capacity 20% higher than in case of the double-shell lining. In addition, a possibility of a composite single-shell shotcrete layer composed by multiple bonded layers partly involving different contents of high-capacity additives is shown thereby leading to use of less amount of the high-capacity additives on the condition of taking a similar load-bearing capacity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.11
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• pp.957-964
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• 2016

This paper presents numerical investigation on behaviors of the rear cover in the vertical launcher under rocket plume loading by using fluid-structure interaction analysis. The rocket plume loading is modeled by the fully Eulerian method and elasto-plastic behavior of the rear cover is predicted by the total Lagrangian method based on a 9-node planar element. The interface motion and boundary conditions are described by a hybrid particle level-set method within the ghost fluid framework. The present results will be compared with the experimental data in the future.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.547-556
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• 2001

This study presents new method in which to derive the constraint coefficient from the quantity of angular deformation by welding measured by varying the shape of welded joints and the magnitude of constraints by varying the shape of welded joints and the magnitude of constraints by experiment and from the result analyzed by elastic FEM method and then to decide equivalent load with it The numerical analysis results by this new method verified the validity by agreeing with the experimental result on specimen. In addition These results are applicable to the prediction of the quantity of welding deformation for large structures regardless of the size and the shape While in the effects of the constraints based on the shape of welded joints in the case of Butt welding when the constraint coefficients are not considered the deformed quantity is produced larger than one by the experiment and consequently is largely affected by the constraints But in the case of Fillet welding the deformed quantity is seldom affected regardless of considering the constraint coefficients or not.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.80-86
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• 2003

An anaysis on the discharge performance of an impinging-type injector for cavitating flow has been conducted by both numerical and experimental method. The predicted discharge coefficient for cavitating flow agrees well with the measured data showing less than 1% discrepancy. For the case of non-cavitating flow analysis, the disagreement between CFD results and the experimental data is 8%. The discharge coefficient for the cavitating flow decreases with decrease in the Reynolds number. On the other hand, it increases slightly as the Reynolds number increases for the non-cavitating flow because of the reduced viscous effect. From the present study, it is confirmed that the fact that cavitation phenomena should be included to predict accurately the discharge performance of injectors for cavitating flow regime. The uniformity of density and velocity magnitude degraded at the injector exit, and the secondary flow strength through the injector orifice accentuated due to cavitation.

• Journal of the Korean GEO-environmental Society
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• v.12 no.7
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• pp.67-76
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• 2011

In this present study, to evaluate a behavior characteristics of the sea dyke coastal covering stone by sea waves. sea waves act on coastal structures as an impact load. During impact loading, erosion and bluff slumping occur in the coastal structures. Also, the covering stone are worn down by wave impact. The sea dyke has been used near coastal region for protection of infra-structure since 1970s in Korea. The sea dyke consist of dredged sand and covering stone mainly. The damage type of covering stone has been reported since 1970s. However, the interaction of impact load by sea wave with the covering stone has not been investigated yet properly. Mainly damage type of covering stone is an abrasion. But the study of covering stone abrasion is not sufficient. Hence, In this study, it was analyzed the interaction of impact load by sea wave and the covering stone during sea wave action on coastal structures. In order to analyze the behavior characteristics of coastal covering stone considering the magnitude and period of impact loading and to evaluate the displacement increment of covering stone during impact load, numerical analysis was carried out considering impact loading by sea wave.