Papers by Author: Yoon Koog Hwang

Abstract: In this study, a Buoyancy Preflex Method was introduced to enhance structural safety and performances for a large floating structure on which recently many studies are actively conducted worldwide. To demonstrate the effect of the Buoyancy Preflex introduced to the floating structure, an analytical study was conducted using parameters such as the ratio of the lengths of center modules to those of end modules. The analysis models for parameter were modeled into 5 cases, then a hydrostatic analysis on live load was selected from Equivalent Static analysis methods, then was conducted. The analysis procedure was divided into two steps, before and after live loading. As The result of this study, first analysis step, it was confirmed by each analysis model that excellent buoyancy preflexes were introduced. Even after the live loading, the 2nd analysis step, compressive stresses occurred at the bottom slabs of all analysis models, which enabled a determination that all analysis models can afford to secure safety and structural performance against live load.

Abstract: In this study, in order to verify wave induced buoyancy effects by wave conditions of wave height and period, experimental studies were conducted to the floating structures of pontoon type. A series of small-scale tests with various wave cases were performed to the pontoon models. Two small-scale pontoon models having different bottom details were fabricated and tested under the five different wave cases. Six hydraulic pressure gauges were attached on the bottom of pontoon models and wave induced hydraulic pressure was measured during the tests. Finally, hydraulic pressure subjected to the bottom of pontoon models were compared with each other. As the results of this study, it was found that wave induced hydraulic pressures at bottom were dependent on the wave period as well as wave height, and waffled bottom shape hardly influenced on wave induced hydraulic pressure.

Abstract: In general, structures in service gradually lose their original performance-level over time due to initial defects in design and construction, or exposure to unfavorable external conditions such as repeated loading or deteriorating environment, and in extreme cases, may collapse. So, in order to maintain the serviceability of structures at optimal level, advanced structure measuring system which can inform optimal time point and method of maintenance is required in addition to accurate prediction of residual life of the structure by periodic inspection. In Korea, the large-scale project for the safety network integration for long-term smart monitoring systems for bridge structures started in 2007, and this is the second year of the project. In this system, various structure types such as bridge, tunnels and cut slopes were considered with an emphasis on safety. The purpose of this system is to integrate the operation centers for these structure types in order to control and evaluate the structure’s real-time safety level through measured behavioral data. In this paper, the progress methodology for this network system and the smart monitoring system installation techniques for each structure types are briefly suggested.