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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Korean Society of Hazard Mitigation
Journal Basic Information
Journal DOI :
Korean Society of Hazard Mitigation
Editor in Chief :
Moo Jong Park
Volume & Issues
Volume 5, Issue 4 - Dec 2005
Volume 5, Issue 3 - Sep 2005
Volume 5, Issue 2 - Jun 2005
Volume 5, Issue 1 - Mar 2005
Selecting the target year
Subsurface Imaging Technology For Damage Detection of Concrete Structures Using Microwave Antenna Array
Kim, Yoo-Jin ; Choi, Ko-Il ; Jang, Il-Young ;
Journal of Korean Society of Hazard Mitigation, volume 5, issue 2, 2005, Pages 1~8
Microwave tomographic imaging technology using a bi-focusing operator has been developed in order to detect the internal voids/objects inside concrete structures. The imaging system consists of several cylindrical or planar array antennas for transmitting and receiving signals, and a numerical focusing operator is applied to the external signals both in transmitting and in receiving fields. In this study, the authors developed 3-dimensional (3D) electromagnetic (EM) imaging technology to detect such damage and to identify exact location of steel rebars or dowel. The authors have developed sub-surface two-dimensional (2D) imaging technique using tomographic antenna array in previous works. In this study, extending the earlier analytical and experimental works on 2D image reconstruction, a 3D microwave imaging system using tomographic antenna way was developed, and multi-frequency technique was applied to improve quality of the reconstructed image and to reduce background noises. Numerical simulation demonstrated that a sub-surface image can be successfully reconstructed by using the proposed tomographic imaging technology. For the experimental verification, a prototype antenna array was fabricated and tested on a concrete specimen.
A New Model for Forecasting Inundation Damage within Watersheds - An Artificial Neural Network Approach
Chung, Kyung-Jin ; Chen, Huaiqun ; Kim, Albert S. ;
Journal of Korean Society of Hazard Mitigation, volume 5, issue 2, 2005, Pages 9~16
This paper presents the use of an Artificial Neural Network (ANN) as a viable means of forecasting Inundation Damage Area (IDA) in many watersheds. In order to develop the forecasting model with various environmental factors, we selected 108 watershed areas in South Korea and collected 49 damage data sets from 1990 to 2000, of which each set is composed of 27 parameters including the IDA, rainfall amount, and land use. After successful training processes of the ANN, a good agreement (R=0.92) is obtained (under present conditions) between the measured values of the IDA and those predicted by the developed ANN using the remaining 26 data sets as input parameters. The results indicate that the inundation damage is affected by not only meteorological information such as the rainfall amount, but also various environmental characteristics of the watersheds. So, the ANN proves its present ability to predict the IDA caused by an event of complex factors in a specific watershed area using accumulated temporal-spatial information, and it also shows a potential capability to handle complex non-linear dynamic phenomena of environmental changes. In this light, the ANN can be further harnessed to estimate the importance of certain input parameters to an output (e.g., the IDA in this study), quantify the significance of parameters involved in pre-existing models, and contribute to the presumption, selection, and calibration of input parameters of conventional models.
The Analysis of Critical Duration of uncontrolled single detention facility in Small Catchment
Park, Jong-Young ; Shin, Chang-Dong ; Lee, Jung-Sik ;
Journal of Korean Society of Hazard Mitigation, volume 5, issue 2, 2005, Pages 17~28
The objective of this study is to evaluate the critical duration between detention facility and flood control facility of small size catchment. 4 small size catchments are applied for hydrological analysis and rainfall excess is computed by using the NRCS Runoff Curve Number method. The critical duration of detention facility and flood control facility is evaluated using the concept of allowable release rate. The conclusions studied in this study are as follows; (1) The type of temporal pattern of design rainfall which causes maximum storage ratio has resulted in Huff's 2 quartile in case of the use of the concept of allowable release rate. (2) Based on (1) of conclusion, the critical durations of flood control facility are similar to those of detention facility, which is used for uncontrolled single detention pond.
Integrity Assessment of Spread Footing Pier for Scour Using Natural Frequency
Park, Byung-Cheol ; Oh, Keum-Ho ; Park, Seung-Bum ;
Journal of Korean Society of Hazard Mitigation, volume 5, issue 2, 2005, Pages 29~35
In Korea more than ninety bridges are collapsed every year by flood, which causes the scour of pier foundation. Researches on the quantitative assessment method to assess the integrity of bridge against scour have not been organized systematically in the bridge design practice and maintenance area. In this study, dynamic characteristics assessment experiments are carried out as an emergency inspection method to assess the integrity of the pier foundation for scour after a flood. According to the dynamic characteristics assessment experiment, which simulates foundation scour of the spread footing pier, foundation scour can be evaluated by the first mode natural frequency of the pier.
Application of Urban Hydrologic Monitoring System for Urban Runoff Analysis
Seo, Kyu-Woo ;
Journal of Korean Society of Hazard Mitigation, volume 5, issue 2, 2005, Pages 37~44
It reflects well feature of slope that is characteristic of urban river basin of Busan local. In this study, process various hydrological data and basin details data which is collected through basin basis data, hydrological monitoring system(EMS-DEU) and automatic water level equipment(AWS-DEU) for urban flood disaster prevention and use as basin input data of ILLUDAS, SWMM and HEC-HMS in order to examine outflow feature of experiment basin and then use in reservoir design of experiment basin through calibration and verification about HEC-HMS. Inserted design rainfall for 30 years that is design criteria of creek into HEC-HMS and then calculated design floods according to change aspect of the impermeable rate. Capacity of reservoir was determined on the outflow mass curve. Designed detention pond(volume
) at last outlet upper stream of experiment basin, after designing reservoir. It could be confirmed that the peak flow was reduced resulting from examining outflow aspect. Designing reservoir must decrease outflow of urban areas.
Investigation on Cloud Properties for Fog Modification at Daegwallyeong Mountains
Yang, Ha-Young ; Oh, Sung-Nam ;
Journal of Korean Society of Hazard Mitigation, volume 5, issue 2, 2005, Pages 45~56
Cloud meteorological properties over Daegwallyeong mountain area were analyzed for experimental cloud seeding which related to a feasibility study of fog modification. The cloud seeding for fog modification has been refocused to using hygroscopic chemical to dissipate warm fog. In this study, the statistics of fog observations were analyzed and discussed. Fog properties mostly showed the Summer warm fog, the early morning occurrences before to 6 o'clock AM, and 7 to 9 o'clock dissipation in the statistics. In the Spring and Winter season an easterly wind produced cold fog which is good applied with AgI seeding agents. Extrapolation of these results suggests that the suitable seeding method and material for fog modification will be introduced from the actual seeding experiments in the cold and warm fog.
Dynamic Behavior of Unsaturated Decomposed Granite Soils under Low Shear Strain Amplitude
Huh, Kyung-Han ; Baek, Joong-Yuk ;
Journal of Korean Society of Hazard Mitigation, volume 5, issue 2, 2005, Pages 57~63
In case of general structures, it has been known that the strain amplitude band experienced by the base in a state of service load is less than 1% and most of the base show low, strain amplitude behavior less than 0.01%. In this study examining the influence affected to dynamic behavior in a condition of the low strain amplitude of unsaturated decomposed granite soils, the resonant column test, using some samples in Su-won area, has been performed for each degree of saturation resulted from different void ratios and confined stress. It is found out that the minimum value of the damping ratio occurred in roughly
according to void ratios regardless of confined pressure in the same manner with the case of the maximum shear elastic modulus; and it is estimated that for the influence of surface tension in the optimum degree of saturation, the damping ratio appears to be least.