• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.202-216
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• 1999

To control the motion of building structures under earthquakes their response should be measured first by various sensors and transformed into the control forces using some control algorithms. Of many control algorithms linear quadratic control is widely used as it is easy to implement and analyze. However the algorithms has the disadvantage that it needs the real-time measurements of all state variables(i.e, building's displacements and velocities) which are difficult to achieve for the building structures under earthquakes. Thus the practical algorithms employing output feedback are developed. In this paper LQG algorithm is used for the control of the building model with an active mass driver. The building's acceleration is used to obtain the control gain and the Kalman filter gain. The LQG control strategy is verified with the experimental study on the one-storybuilding model equipped with the active mass driver. This paper demonstrates experimentally the efficacy of the LQG algorithm based on the active mass driver system in reducing the response of seismically excited buildings.

• Wind and Structures
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• v.3 no.4
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• pp.221-241
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• 2000

Structural dynamics usually applies modal transformation rules aimed at de-coupling and/or minimizing the equations of motion. Proper orthogonal decomposition provides mathematical and conceptual tools to define suitable transformed spaces where a multi-variate and/or multi-dimensional random process is represented as a linear combination of one-variate and one-dimensional uncorrelated processes. Double modal transformation is the joint application of modal analysis and proper orthogonal decomposition applied to the loading process. By adopting this method the structural response is expressed as a double series expansion in which structural and loading mode contributions are superimposed. The simultaneous use of the structural modal truncation, the loading modal truncation and the cross-modal orthogonality property leads to efficient solutions that take into account only a few structural and loading modes. In addition the physical mechanisms of the dynamic response are clarified and interpreted.

• Structural Engineering and Mechanics
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• v.17 no.1
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• pp.29-50
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• 2004

A total life model was developed to assess the service life of aging aircraft. The primary focus of this paper is the development of crack growth life projection using the response surface method. Crack growth life projection is a necessary component of the total life model. The study showed that the number of load cycles N needed for a crack to propagate to a specified size can be linearly related to the geometric parameter, material, and stress level of the component considered when all the variables are transformed to logarithmic values. By the Central Limit theorem, the ln N was approximated by Gaussian distribution. This Gaussian model compared well with the histograms of the number of load cycles generated from simulated crack growth curves. The outcome of this study will aid engineers in designing their crack growth experiments to develop the stochastic crack growth models for service life assessments.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.107-112
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• 1999

This paper presents a time domain method for soil-structure interaction analysis for seismic loadings. It is based on the finite element formulation incorporating analytical frequency-dependent infinite elements for the far-field soil. The dynamic stiffness matrices of the far-field region formulated in frequency domain using the present method can be easily transformed into the corresponding matrices in time domain. Hence the response can be analytical computed in time domain. Example analysis has been carried out to verify the present method for an embedded block in a multi-layered half-space. The present methods can be easily extended to the nonlinear analysis since the response analysis is carried out in time domain.

• Water Engineering Research
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• v.6 no.3
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• pp.131-147
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• 2005

Today, a trend that tries to return the artificial space of a river to a natural one is expanding. But in Korea, which lies in the monsoon climate zone, rivers endure flood damage every year. Moreover, climatic change from global warming causes severe variations in precipitation patterns. Until recently, river restoration practices in Korea have followed partial restoration. These restorative treatments transformed artificial structures of the stream to natural ones and introduced natural vegetation by imitating natural or semi-natural streams. Treatment transformed the riparian structure and increased the diversity of micro-topography and vegetation. Furthermore, restoration recovered species composition, increased species diversity, and inhibited the establishment of exotic species. In particular, the Suip stream, which was left to its natural process for approximately 50 years, recovered its natural features almost completely through passive restoration. An urban stream, the Yangjae, and a rural stream, the Dongmoon, were restored partially by applying ecological principles. On the contrary, technological treatment applied to recover flood damage induced species composition far from the natural vegetation and decreased species diversity. Additionally, this treatment increased exotic species. The same results were found also in benthic invertebrate and fish fauna. The above-mentioned results reflect the importance of ecological considerations in river management.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1194-1201
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• 2006

All the loads in the real world are dynamic loads and structural optimization under dynamic loads is very difficult. Thus the dynamic loads are often transformed to static loads by dynamic factors, which are believed equivalent to the dynamic loads. However, due to the difference of load characteristics, there can be considerable differences between the results from static and dynamic analyses. When the natural frequency of a structure is high, the dynamic analysis result is similar to that of static analysis due to the small inertia effect on the behavior of the structure. However, if the natural frequency of the structure is low, the inertia effect should not be ignored. Then, the behavior of the dynamic system is different from that of the static system. The difference of the two cases can be explained from the relationship between the homogeneous and the particular solutions of the differential equation that governs the behavior of the structure. Through various examples, the difference between the dynamic analysis and the static analysis are shown. Also dynamic response optimization results are compared with the results with static loads transformed from dynamic loads by dynamic factors, which show the necessity of the design considering dynamic loads.

• Journal of Life Science
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• v.13 no.5
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• pp.551-558
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• 2003

Hepatitis C Virus (HCV) is associated with a severe liver disease and increased frequency in the development of hepatocellular carcinoma. Overexpression of HCV core protein is known to transform fibroblast cells. Phospholipase D (PLD) activity is commonly elevated in response to mitogenic signals, and PLD has been also reported to be overexpressed and hyperactivated in some human cancer. The aim of this study was to understand how PLD can be regulated in HCV core protein-transformed NIH3T3 mouse fibroblast cells. We observed that in unstimulated state, basal PLD activity was higher in NIH3T3 cells overexpressing HCV core protein than in vector-transfected cells. Although expression of PLD and protein kinase C (PKC) in core protein-transformed cells was similar with that of control cells, phorbol 12-myristate 13-acetate (PMA), which is known to activate PKC, stimulated significantly PLD activity in core protein-transformed cells, compared with that of the control cells. PLD activity assay using PKC isozyme-specific inhibitor, and PKC translocation experiment showed that PKC-$\delta$ was mainly involved in the PMA-induced PLD activation in the core-transformed cells. Taken together, these results suggest that PLD might be implicated in core protein-induced transformation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1949-1957
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• 2000

All the loads in the real world act dynamically on structures. Since dynamic loads are extremely difficult to handle in analysis and design, static loads are utilized with dynamic factors. The dyna mic factors are generally determined based on experiences. Therefore, the static loads can cause problems in precise analysis and design. An analytical method based on modal analysis has been proposed for the transformation of dynamic loads into equivalent static load sets. Equivalent static load sets are calculated to generate an identical displacement field in a structure with that from dynamic loads at a certain time. The process is derived and evaluated mathematically. The method is verified through numerical tests. Various characteristics are identified to match the dynamic and the static behaviors. For example, the opposite direction of a dynamic load should be considered due to the vibration response. A dynamic bad is transformed to multiple equivalent static loads according to the number of the critical times. The places of the equivalent static load can be different from those of the dynamic load. An optimization method is defined to use the equivalent static loads. The developed optimization process has the same effect as the dynamic optimization which uses the dynamic loads directly. Standard examples are solved and the results are discussed

• Journal of Veterinary Clinics
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• v.27 no.1
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• pp.66-70
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• 2010

Reference interval is critical for interpreting laboratory results, monitoring response to therapy and predicting the prognosis of the patients in clinical settings. The aim of the present study was to update established reference intervals for routine hematologic and serum chemistry values for a population of clinically healthy dogs (range, 1-8 years) seen in an animal hospital. Blood was obtained by venipuncture while animals were physically restrained, and samples were analyzed for 9 chemistries on MS9-5H (Melot Schloesing Lab, France) and 6 hematology on Vet Test 8008 (IDEXX, USA). Data from 105 dogs (52 males and 53 females) for hematology and 113 dogs (37 males and 76 females) for chemistry were used to determine reference intervals using the parametric, nonparametric and bootstrap methods. Prior to analysis, all parameters were tested for normal distribution using Anderson-Darling criterion. Of the 9 biochemical analytes, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatinine, total protein, and glucose concentrations did not fit normal distribution for both original and transformed data. All but eosinophil count satisfied normal distribution for either original or transformed data. Parametric method can be used for original cholesterol concentrations, RBC, WBC, and neutrophil counts. This technique can also be used for power-transformed values of blood urea nitrogen concentrations and for logarithm of lymphocyte and monocyte counts. Non-parametric or bootstrap method was the preferred choice for the remaining 7 biochemical parameters and eosinophil count as they did not follow normal distributions. All three statistical techniques performed in similar reference intervals. When establishing reference intervals for clinical laboratory data, it is essential to assess the distribution of the original data to increase the accuracy of the interval, and non-parametric or bootstrap methods are of alternative for the data that do not fit normal distribution.

• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1372-1381
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• 2017

In this paper, a texture feature extraction method using local energy and local correlation of Gabor transformed images is proposed and applied to an image retrieval system. The Gabor wavelet is known to be similar to the response of the human visual system. The outputs of the Gabor transformation are robust to variants of object size and illumination. Due to such advantages, it has been actively studied in various fields such as image retrieval, classification, analysis, etc. In this paper, in order to fully exploit the superior aspects of Gabor wavelet, local energy and local correlation features are extracted from Gabor transformed images and then applied to an image retrieval system. Some experiments are conducted to compare the performance of the proposed method with those of the conventional Gabor method and the popular rotation-invariant uniform local binary pattern (RULBP) method in terms of precision vs recall. The Mahalanobis distance is used to measure the similarity between a query image and a database (DB) image. Experimental results for Corel DB and VisTex DB show that the proposed method is superior to the conventional Gabor method. The proposed method also yields precision and recall 6.58% and 3.66% higher on average in Corel DB, respectively, and 4.87% and 3.37% higher on average in VisTex DB, respectively, than the popular RULBP method.