• Bulletin of the Society of Naval Architects of Korea
• /
• v.13 no.1
• /
• pp.17-23
• /
• 1976

Some methods of analysis of rectangular plates under distributed load of various intensity with interior supports are presented herein. Analysis of many structures such as bottom, side shell, and deck plate of ship hull and flat slab, with or without internal supports, Floor systems of bridges, included crthotropic bridges is a problem of plate with elastic supports or continuous edges. When the four edges of rectangular plate is simply supported, the double Fourier series solution developed by Navier can represent an exact result of this problem. If two opposite edges are simply supported, Levy's method is available to give an "exact" solution. When the loading condition and supporting condition of a plate does not fall into these cases, no simple analytic method seems to be feasible. Analysis of a simply supported rectangular plate under irregularly distributed loads of various intensity with internal supports is carried out by applying Navier solution well as the "Principle of Superposition." Finite difference technique is used to solve plates under irregularly distributed loads of various intensity with internal supports and with various boundary conditions. When finite difference technique is applied to the Lagrange's plate bending equation, any of fourth order derivative term in this equation produces at least five pivotal points leading to some troubles when the resulting linear algebraic equations are to be solved. This problem was solved by reducing the order of the derivatives to two: the fourth order partial differential equation with one dependent variable, namely deflection, is changed to an equivalent pair of second order partial differential equations with two dependent variables. Finite difference technique is then applied to transform these equations to a set of simultaneous linear algebraic equations. Principle of Superposition is then applied to handle the problems caused by concentrated loads and interior supports. This method can be used for the cases of plates under irregularly distributed loads of various intensity with arbitrary conditions such as elastic supports, or continuous edges with or without interior supports, and this method can also be solve the influence values of deflection, moment and etc. at arbitrary position of plates under the live load.

• The KIPS Transactions:PartD
• /
• v.8D no.5
• /
• pp.473-482
• /
• 2001

Integrated heterogeneous database systems provide the unified interface for users and applications today in order to access the underlying diverse data sources located in different sites. The multiple heterogeneous data sources have the different and specialized data structures and transaction processing capabilities. Because of local autonomy, the local system does not have the capability of cooperation to control the global transaction. Hence designing the global transaction manager with supporting the global serializability is difficult task. To resolve the well-known indirect conflict, we define the global transaction model by using the characteristics of global integrity constraints. And then we propose the site-locking operation and its protocol to manage the global transaction. The correctness and analysis of our site-locking protocol is proved and performance gain over the related other methods is also estimated in this paper.

• The KIPS Transactions:PartD
• /
• v.15D no.4
• /
• pp.557-568
• /
• 2008

An ontology as the core element of Semantic Web is a formal specification of a conceptualization of shared domain knowledge. The use of well-defined ontologies can increase the quality of interoperable information systems in the area of Semantic Web. However, in practice, it is not easy to develop high-quality ontologies which have no errors. Therefore, with methodologies for ontology design, various methods or tools for ontology analysis supporting for error-detection might be very helpful for ontology developers. In this paper, we propose a novel approach for analyzing the core constructs of ontology based on the Formal Concept Analysis and develop a tool that supports error-checking ontologies. Our approach can serve not only as a guidance to modify the existing ontologies, but also as a valuable tool in developing high-quality ontologies.

• Wind and Structures
• /
• v.23 no.1
• /
• pp.1-18
• /
• 2016

This work experimentally and numerically analyzes the flow configurations and the dynamic wind loads on panels of rectangular L/h 5:1 cross section mounted on a structural frame of rectangular bars of L/h 0.5:1, corresponding to a radar structure. The fluid dynamic interaction between panels and frame wakes imposes dynamic loads on the panels, with particular frequencies and Strouhal numbers, different from those of isolated elements. The numerical scheme is validated by comparison with mean forces and velocity spectra of a panel wake obtained by wind tunnel tests. The flow configuration is analyzed through images of the numerical simulations. For a large number of panels, as in the radar array, their wakes couple in either phase or counter-phase configurations, changing the resultant forces on each panel. Instantaneous normal and tangential force coefficients are reported; their spectra show two distinct peaks, caused by the interaction of the wakes. Finally, a scaled model of a rectangular structure comprised of panels and frame elements is tested in the boundary layer wind tunnel in order to determine the influence of the velocity variation with height and the three-dimensionality of the bulk flow around the structure. Results show that the unsteady aerodynamic loads, being strongly influenced by the vortex shedding of the supporting elements and by the global 3-D geometry of the array, differ considerably on a panel in this array from loads acting on an isolated panel, not only in magnitude, but also in frequency.

• Steel and Composite Structures
• /
• v.20 no.1
• /
• pp.127-145
• /
• 2016

Composite column design is strongly influenced by the computation of the critical buckling load, which is very sensitive to the effective flexural stiffness (EI) of the column. Because of this, the behaviour of a composite column under lateral loading and its response to deflection is largely determined by the EI of the member. Thus, prediction models used for composite member design should accurately mirror this behaviour. However, EI varies due to several design parameters, and the implementation of high-strength materials, which are not considered by the current composite design codes of practice. The reliability of the design methods from six codes of practice (i.e., AS 5100, AS/NZS 2327, Eurocode 4, AISC 2010, ACI 318, and AIJ) for composite columns is studied in this paper. Also, the reliability of these codes of practice against a serviceability limit state criterion are estimated based on the combined use of the test-based statistical procedure proposed by Johnson and Huang (1997) and Monte Carlo simulations. The composite columns database includes 100 tests of circular concrete-filled tubes, rectangular concrete-filled tubes, and concrete-encased steel composite columns. A summary of the reliability analysis procedure and the evaluated reliability indices are provided. The reasons for the reliability analysis results are discussed to provide useful insight and supporting information for a possible revision of available codes of practice.

• Journal of the Society of Naval Architects of Korea
• /
• v.50 no.1
• /
• pp.33-40
• /
• 2013

Since most of yacht sails are made of thin fabric, they form cambered sail shape that can efficiently generate lift power by aerodynamic interaction and by external force delivered from supporting structures such as mast and boom. When the incident flow and external force alter in terms of volume or condition, the shape of sail also change. This deformation in shape has impact on the peripheral flow and aerodynamic interaction of the sail, and thus it is related to the deformation of the sail in shape again. Therefore, the precise optimization of aerodynamic performance of sail requires fluid-structure interaction (FSI) analysis. In this study, the simplified sail without camber was under experiment for one-way FSI that uses the result of flow analysis to the structural analysis as load condition in an attempt to fluid-structure interaction phenomenon. To confirm the validity of the analytical methods and the reliability of numerical computation, the difference in deformation by the number of finite element was compared. This study reproduced the boundary conditions that sail could have by rigs such as mast and boom and looked into the deformation of sail. Sail has non-linear deformation such as wrinkles because it is made of a thin fabric material. Thus non-linear structural analysis was conducted and the results were compared with those of analysis on elastic material.

• International Journal of High-Rise Buildings
• /
• v.4 no.3
• /
• pp.171-180
• /
• 2015

A shaking table test was conducted at the E-Defense shaking table facility to investigate the damage and collapse behavior of a steel high-rise building under exceedingly large ground motions. The specimen is a one-third scale 18-story steel moment frame designed and constructed according to design specifications and practices used in the 1980s and 1990s. The shaking table tests used a long-duration, long-period ground motion simulated for a sequential Tokai, Nankai, and Nankai earthquake scenario. The building specimen was subjected to a series of progressively increasing scaled motions until it completely collapsed. The damage to the steel frame began through the yielding of beams along lower stories and column bases of the first story. After several excitations by increasing scaled motions, cracks initiated at the welded moment connections and fractures in the beam flanges spread to the lower stories. As the shear strength of each story decreased, the drifts of lower stories increased and the frame finally collapsed and settled on the supporting frame. From the test, a typical progression of collapse for a tall steel moment frame was obtained, and the hysteretic behavior of steel structural members including deterioration due to local buckling and fracture were observed. The results provide important information for further understanding and an accurate numerical simulation of collapse behavior.

• Journal of Periodontal and Implant Science
• /
• v.38 no.3
• /
• pp.429-436
• /
• 2008

Purpose: The goal of periodontal regenerative therapy is to replace bone, cementum, and periodontal ligament on a previously diseased root surface, which has suffered the loss of these supporting structures. To accomplish the regeneration, a number of surgical procedures have been advocated throughout the years. There seems to be a potential for some spontaneous periodontal tissue regeneration in the bottom of periodontal defect following open flap debridement alone. The aim of this study was to analyse the radiographic bone changes over 2-year after flap operation. Material and Methods: Patients attending the department of periodontics of Kyungpook National University Hospital were studied. Patients had clinical and radiographic evidence of infrabony defect(s). forty two sites of 33 patients aged 26 to 65 (mean age 45.5) were treated by flap operation with or without osseous surgery. Baseline and over 2-year follow-up radiographs were collected and evaluated for this study. Radiographic assessment includes a bone fill, bone crest change, defect resolution, and % of defect resolution. Pre- and post-treatment differences between variables (maxilla and mandible, gender, defect depth, defect angle) using the paired t-test were examined. Result: We observed 0.74 mm of bone fill, 0.66 mm of crestal resorption, 1.40 mm of defect resolution, and 27% of percentage of defect resolution. Mandible, women, deeper initial defect depth, narrower initial defect angle showed greater bone fill, defect resolution, and % of defect resolution. Conclusion: The results of this study suggest that the use of flap operation did enhance the outcome in terms of radiographically detectable bone fill. Both treatment resulted in some loss of crestal bone height.

• The Journal of the Korea Contents Association
• /
• v.3 no.2
• /
• pp.87-95
• /
• 2003

Prompt and efficient information collection on each research area is emerging as the key factor of national technology competitiveness in industrialized society. Accordingly, constructing a variety of specialized DBs as the tool for supporting R&D activities and providing appropriate information are essential task to be solved in promoting R&D productivity. On this study, We have developed ceramics material property DB to support and facilitate R&D activities of industry, academia and research institutes. The ceramic property DB which was regarded as the most important DB surveyed from korean done for scientists and researchers was selected. To develop this DB, us have designed DB customized for domestic users after analyzing items and structures of ceramic material property information. We hope that R&D researchers can save time and cost in acquiring property information and the R&D productivity will be improved by utilizing our research result.

• Journal of the Korean Institute of Gas
• /
• v.8 no.2 s.23
• /
• pp.48-53
• /
• 2004

Korea Gas Corporation(KOGAS) is a Liquified Natural Gas(LNG) supplier through out the Korea. LNG, which is imported wholly from foreign countries, is compressed 1/600 for easy transportation and is stored in a liquid state in the storage tanks at Incheon, Pyeongtaek and Tongyeong. At LNG receiving terminals, LNG is vaporized to natural gas before supplying to City Gas Consumer or Power Plant. The secondary pump is a equipment which compress LNG from $10 kgf/cm^2$ to $70 kgf/cm^2$. The secondary pump at Tongyeong LNG receiving terminal is consisted of two pumps in one underground PIT, and is connected to supporting structures. It is therefore expected that there is a vibration problem with the pump and was found that high level vibration was occurred in a low frequency band(5${\~}$10Hz). In this paper, the vibration of secondary pump was analyzed, and the main cause of vibration was found out.