• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.01a
• /
• pp.263-266
• /
• 2009

When video packets are transmitted over error-prone networks, the leaky prediction can be used to mitigate the effect of error propagation. The leaky factor provides trade-off between coding efficiency and error resilience in the leaky prediction. In this paper, we propose an improved leaky prediction method where the leaky factor is adaptively determined for each frame by minimizing the estimated end-to-end distortion at the encoder. Experimental results show that the proposed method with the adaptive leaky factor shows the better performance of the error robustness as compared with the conventional method.

• Steel and Composite Structures
• /
• v.52 no.1
• /
• pp.109-119
• /
• 2024

This study presents a replaceable reduced beam section (R-RBS) located at the column end in moment resisting frames (MRFs). An end of the R-RBS is connected to column by using end-plate moment connection and the other end of that is connected to main beam with beam splice connection. Therefore, the RBS that is expected to yield under an earthquake can be easily replaceable. Geometry of the RBS and the thickness of the beam splice connection are the prime variables of this study. A total of eight experimental test was carried out to examine the seismic performance of the proposed R-RBS with the connection details. The results obtained from experimental studies demonstrated that plate sizes of the beam splice connection significantly affect the seismic performance of RBSs used in MRFs.

• Journal of the Korean Society for Railway
• /
• v.2 no.1
• /
• pp.16-27
• /
• 1999

The purpose of this study is to suggest the effective analytical procedure using finite element model for the crashworthiness of motorized trailer of high speed train. The static crush of rectangular section frame is analyzed by experiment and numerical simulation. The equivalent thickness distribution of the aluminum frame ensuring the same energy absorption as the steel frame is obtained. In the analysis of end-on collision of TGV-K, deformed pattern and section forces are obtained, and the effect of crushable zone are examined. The numerical results are applied to the design of motorized trailer of Korean high speed train.

• Journal of the Korean School Mathematics Society
• /
• v.13 no.4
• /
• pp.595-618
• /
• 2010

To grow as talents with future oriented knowledge and creativity, students need imaginative power and creativeness, and to that end, mathematics and science subjects may help. Students need activities that help gain explorative mind for new things, concentrating ability, researching ability and creativeness, and such attributes can be improved through the activities of making various shapes utilizing space geometry in 4D-frame. Such activities not only contribute to defining ability in mathematics but also cherish the qualifications required as architects and space scientists.

• Journal of Mechanical Science and Technology
• /
• v.15 no.1
• /
• pp.108-116
• /
• 2001

The in-cylinder flow field of gasoline engine comprises unsteady compressible turbulent flows caused by the intake port, combustion chamber geometry. Thus, the quantitative analysis of the in-cylinder flow characteristics plays an important role in the improvement of engine performances and the reduction of exhaust emission. In order to obtain the quantitative analysis of the in-cylinder gas flows for a gasoline engine, the single-frame particle tracking velocimetry was developed, which is designed to measure 2-dimensional gas flow field. In this paper, influences of the swirl and tumble intensifying valves on the in-cylinder flow characteristics under the various intake flow conditions were investigated by using this PTV method. Based on the results of experiment, the generation process of swirl and tumble flow in a cylinder during intake stroke was clarified. Its effect on the tumble ratio at the end of compression stroke was also investigated.

• Journal of Korean Association for Spatial Structures
• /
• v.1 no.1 s.1
• /
• pp.135-142
• /
• 2001

This paper proposes structural analysis on the World Wide Web to form a part of the architectural design project. It purposes modeling space frames and a structural analysis program on the internet only by inputting basic data for forming a shape in the whole phase of space frame analysis. The analysis data is conducted by Oracle DBMS(DataBase Management System), GUI(Graphic User Internet) by Java Applet and connection with server and database by Java Servlet respectively. The result from modeling and analysis is provided as graphic and text file forms by web browsers. Programs can be executed irrespective of user's OS by using internet and highly-secured system is constructed taking advantage of Java. Of great efficiency is maintaining and recycling data as the whole is dealt by database from the beginning to the end of program.

• Earthquakes and Structures
• /
• v.11 no.1
• /
• pp.45-61
• /
• 2016

Structures with soft story irregularity have been seriously damaged in earthquakes. Therefore, the analysis of dynamic behavior of structures with soft story irregularity is of great value and relevance. In this study, a certain method will be used to discover the displacements and internal forces and to find out results about soft story irregularity. For this study, the multi-story frame-hinged shear wall system has been used as a model according to the continuous calculation system. The dynamic characteristics of the system have been obtained by analyzing the governing differential equation of the system. The dynamic characteristics have been calculated for a practical and quick analysis as indicated in tables. The suggested method is wholly based on manual calculation. A spectral analysis can be easily conducted with the help of Tables provided by this study. A sample has been solved and compared to the finite elements method to study the suitability of the method suggested at the end of this study.

• Steel and Composite Structures
• /
• v.11 no.1
• /
• pp.21-38
• /
• 2011

This study examines the influence of curved, steel, I-girder bridge configuration on girder end reactions and cross frame member forces during seismic events. Simply-supported bridge finite element models were created and examined under seismic events mimicking what could be experienced in AASHTO Seismic Zone 2. Bridges were analyzed using practical ranges of: radius of curvature; girder and cross frame spacings; and lateral bracing configuration. Results from the study indicated that: (1) radius of curvature had the greatest influence on seismic response; (2) interior (lowest radius) girder reactions were heavily influenced by parameter variations and, in certain instances, uplift at their bearings could be a concern; (3) vertical excitation more heavily influenced bearing and cross frame seismic response; and (4) lateral bracing helped reduce seismic effects but using bracing along the entire span did not provide additional benefit over placing bracing only in bays adjacent to the supports.

• Structural Engineering and Mechanics
• /
• v.77 no.1
• /
• pp.37-46
• /
• 2021

In this study, a method for free vibration analysis of wall-frame systems built on weak soil is proposed. In the development of the method, the wall-frame system that constitutes the superstructure was modeled as flexural-shear beam. In the study, it is accepted that the soil layers are isotropic, homogeneous and elastic, and the waves are only vertical propagating shear waves. Based on this assumption, the soil layer below is modeled as an equivalent shear beam. Then the differential equation system that represented the behavior of the whole system was written for both regions in a separate way. Natural periods were obtained by solving the differential equations by employing boundary conditions. At the end of the study, two examples were solved and the suitability of the proposed method to the Finite Element Method was evaluated.

• Journal of Korean Association for Spatial Structures
• /
• v.23 no.4
• /
• pp.59-69
• /
• 2023

Recently, the occurrence frequency of earthquake has increased in Korea, and the interests for seismic reinforcement of existing school buildings have been raised. To this end, the seismic performance evaluations for school buildings that did not accomplish the seismic design are required. In particular, this study checks the eigenvalue analysis, pushover curves, maximum base shears, performance points and story drift ratios, and then analyzes the seismic performance characteristics according to bracing configuration of steel frame system reinforcement. Also, this study presents the practical field application methods through the comparison of analysis results for the seismic performance characteristics.