• Steel and Composite Structures
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• v.48 no.2
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• pp.207-233
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• 2023

Steel-concrete composite box girder bridges are widely used in the construction of highway and railway bridges both domestically and abroad due to their advantages of being light weight and having a large spanning ability and very large torsional rigidity. Composite box girder bridges exhibit the effects of shear lag, restrained torsion, distortion and interface bidirectional slip under various loads during operation. As one of the most commonly used calculation tools in bridge engineering analysis, one-dimensional models offer the advantages of high calculation efficiency and strong stability. Currently, research on the one-dimensional model of composite beams mainly focuses on simulating interface longitudinal slip and the shear lag effect. There are relatively few studies on the one-dimensional model which can consider the effects of restrained torsion, distortion and interface transverse slip. Additionally, there are few studies on vehicle-bridge integrated systems where a one-dimensional model is used as a tool that only considers the calculations of natural frequency, mode and moving load conditions to study the dynamic response of composite beams. Some scholars have established a dynamic analysis model of a coupled composite beam bridge-train system, but where the composite beam is only simulated using a Euler beam or Timoshenko beam. As a result, it is impossible to comprehensively consider multiple complex force effects, such as shear lag, restrained torsion, distortion and interface bidirectional slip of composite beams. In this paper, a 27 DOF vehicle rigid body model is used to simulate train operation. A two-node 26 DOF finite beam element with composed box beams considering the effects of shear lag, restrained torsion, distortion and interface bidirectional slip is proposed. The dynamic analysis model of the coupled composite box girder bridge-train system is constructed based on the wheel-rail contact relationship of vertical close-fitting and lateral linear creeping slip. Furthermore, the accuracy of the dynamic analysis model is verified via the measured dynamic response data of a practical composite box girder bridge. Finally, the dynamic analysis model is applied in order to study the influence of various mechanical effects on the dynamic performance of the vehicle-bridge system.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.97-102
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• 2005

Because of the limited fossil resources and the need to avoid emissions and toxic waste the future energy supply will be based on a large portion of renewable energies: wind-, solar-, biomass- and geothermal energy. Focus is on the utilization of wind energy coming from onshore- and offshore-sites. Generating electricity from wind is state of the art and feeding large amounts of wind power into the electrical grid will create some additional problems. Suggestions concerning energy storage will be made and the problem of power quality is discussed.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.57-62
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• 2013

Despite the many advantages of magnetic resonance imaging in orthopedic prosthetic body image distortion to the differences in the magnetic susceptibility occurs. Attached to the phantom and pork produced by the same $65{\times}15{\times}2mm$ stainless steel and titanium specimen examined the relationship between magnetic resonance imaging and phantom images, the signal intensity changes of the subcutaneous tissue, fat-suppressed quantitative assessment of the degree through the length of image distortion and pig bones. Stainless steel to titanium to 2.8 times 4.4 times in the longitudinal direction than in the direction of the height of large image distortion, signal strength is relatively low 58.5%. Normal 56.2% compared to the subcutaneous tissue, fat-suppressed, were stainless steel 16.04%, 54.53% titanium. Experimental results than the diagnostic value of magnetic resonance imaging (MRI) images of stainless steel with a titanium metal if better could see.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.62-67
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• 2015

A very large shell-structure built in shipyards like ship hulls or offshore structures are joined by welding through full process. As the welding contains a high thermal cycle at a local area, the welded structures should be distorted unavoidably. Because a distorted ship block should be revised to the designed value before the next stage, the ability to predict and to control the weld distortion is an accuracy level of the yard itself. Despite the ship block size, several present thermal distortion methodologies can deal those sizes, but it is a different story to deal full ship size model. Even a fully constructed ship hull not remaining any welding can have an accuracy issue like outfitting installation problems. Any present thermal distortion methodology cannot accept this size for its recommended element size and the number. The ordinary welding breadth at erection stage is about 20~40 mm. It can hardly be a good choice to make finite element model of these sizes considering human effort and computational environment. The finite element model for structure analysis of a ship hull is prepared at front-end engineering design stage which is the first process of the project. The element size of the model is as fine as the longitudinal space, and it is not proper to obtain a weld distortion at the erection stage. In this study, a methodology is suggested that a weldment can be shrunk at original place instead of using structural finite element model. We cut the original shell elements at erection weld-line and put truss elements between the edges of cut elements for weld shrinkage. Additional truss elements are used to facsimile transverse weld shrinkage which cannot be from the weld-line truss element shrink. They attach to weld-line truss element like twigs from barks. The capacity of developed elements is verified through an accuracy check of erection process of a container vessel at the apt. hull. It can be a useful tool for verifying a centering accuracy after renew and for block-separating planning considering accuracy.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.1
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• pp.79-85
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• 2010

In video standards such as H.264/AVC, motion estimation (ME) / compensation (MC) is regarded as a vital component in a video coder as it consumes a large amount of computation resources. The full search technique, which is used in general video codecs, gives the highest visual quality but also has the problem of significant computational load. To solve this problem, many fast algorithm has benn proposed. Among them, NPDS show that can maintain its video quality very close to the full search technique while achieving computation reduction by using a halfway-stop technique in the calculation of block distortion measure. In this paper, we proposed algorithm by determining minimum distortion measure with predictive motion vector and using the new search order. As the result, we can check that the proposed algorithm reduces the computational load 95% in average compared to the full search, respectively with the PSNR lost about 0.04dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.577-580
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• 2016

One of the effective jamming methods to disturb monopulse radars is a wavefront distortion. Most well-known wavefront distortion is the cross eye technique which uses two transmitters. The cross eye can make angle error regardless of monopulse radar structure but high accuracies of phase and amplitude between two transmitters should be needed to make large angle error. Thus, the accuracies of phase and amplitude are essentially required performance parameters for implementation of wavefront distortion systems and the required values of accuracy is dependant on amount of angle error. In this paper, we derive expressions for minimum required values of phase difference and amplitude ratio according to amount of angle error and analyze the results.

• Health Policy and Management
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• v.20 no.4
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• pp.1-18
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• 2010

Much policy attention has been directed to the concentration of patients in large hospitals, especially in tertiary care hospitals. In order to address the problem, the government has enforced referral requirement for accessing care in tertiary care hospitals by denying insurance benefits to the patients who do not observe the requirement. This approach somehow has failed to produce expected effects although it still exists in theory. The concentration of patients in a certain type of providers results in the distortion of functional differentiation among various types of providers and vice versa. Thus the approaches for the alleviation of the problem should be directed to both patients and providers. However, policy approaches has so far focused on ways of directly affecting patients' choice of a provider neglecting the effects of providers. Based upon the observation, this paper has reviewed selected issues that should be considered in agenda setting for policies concerned with the concentration of patients in large hospitals or the distortion of functional differentiation among health care providers. A brief discussion of each of the issues suggests three general guidelines for the formulation and implementation of policies intended to address the problem. First, attention should be directed to both patients and providers. Secondly, it is necessary to employ diverse measures including regulation, incentives and administrative supports. Thirdly, some of the approaches should be planned from a long range perspective, for it often takes a long time to change some aspects of health care utilization and provision.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.306-320
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• 2010

Modern ultra-large container carriers can be exposed to the unprecedented springing excitation from ocean waves due to their relatively low torsional rigidity. Large deck opening on the deck of container carriers tends to cause warping distortion of hull structure under wave-induced excitation, eventually leading to the higher chance of resonance vibration between its torsional response and incoming waves. To handle this problem, a higher-order B-spline Rankine panel method and Vlasov-beam FE model was directly coupled in the time domain, and the coupled equation was solved by using an implicit iterative method. In order to capture the complicated behavior of thin-walled open section girder, a sophisticated beam-based finite element model was developed, which takes into account warping distortion and shear-on-wall effect. Then, the developed beam model was directly coupled with the time-domain Rankine panel method for hydrodynamic problem by using the fixed-point iteration method. The developed computational scheme was validated through the comparison with the frequency-domain solution on the container carrier model in linear springing regime.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.58.2-58.2
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• 2013

Both peculiar velocities and errors in the assumed redshift-distance relation ("Alcock-Paczynski effect") generate correlations between clustering amplitude and orientation with respect to the line-of-sight. In this talk we propose a novel technique to extract the Alcock-Paczynski, geometric, distortion information from the anisotropic clustering of galaxies in 3-dimensional redshift space while minimizing non-linear clustering and peculiar velocity effects. We capitalize on the recent, large dataset from the Sloan Digital Sky Survey III (SDSS-III), which provides a large comoving sample of the universe out to high redshift. We focus our analysis on the Baryon Oscillation Spectroscopic Survey (BOSS) constant mass (CMASS) sample of 549,005 bright galaxies in the redshift range 0.43

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.4
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• pp.856-873
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• 2011

Reversible watermarking is an open problem in information hiding field, with embedding the encoded bit '1' or '0' into some sensitive images, such as the law enforcement, medical records and military images. The technique can retrieve the original image without distortion, after the embedded message has been extracted. Histogram-based scheme is a remarkable breakthrough in reversible watermarking schemes, in terms of high embedding capacity and low distortion. This scheme is lack of capacity control due to the requirement for embedding large-scale data, because the largest hidden capacity is decided by the amount of pixels with the peak point. In this paper, we propose a reversible watermarking scheme to enlarge the number of pixels with the peak point as large as possible. This algorithm is based on an adaptive edge-guided interpolation, furthermore, hides messages by interpolation-error, i.e. the difference between the original and interpolated image value. Simulation results compared with other state-of-the-art reversible watermarking schemes in this paper demonstrate the validity of the proposed algorithm.