• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.23-33
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• 2012

Recently, landslide disasters caused by severe rain storms and typhoons have been frequently reported. Due to the geomorphologic characteristics of Korea, considerable portion of urban area and infrastructures such as road and railway have been constructed near mountains. These infrastructures may encounter the risk of landslide and debris flow. It is important to evaluate the highly risky locations of landslide and to prepare measures for the protection of landslide in the process of construction planning. In this study, a landslide-risk prediction equation is proposed based on the statistical analysis of 423 landslide data set obtained from field surveys, disaster reports on national road, and digital maps of landslide area. Each dataset includes geomorphologic characteristics, soil properties, rainfall information, forest properties and hazard history. The comparison between the result of proposed equation and actual occurrence of landslide shows 92 percent in the accuracy of classification. Since the input for the equation can be provided within short period and low cost, and the results of equation can be easily incorporated with hazard map, the proposed equation can be effectively utilized in the analysis of landslide-risk for large mountainous area.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.283-291
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• 2012

Various studies regarding the prediction of landslides are underway internationally. Research into disaster prevention with regard to debris flows is a particular focus of research because this type of landslide can cause enormous damage over a short period. The objective of this study is to determine the hazard susceptibility of debris flow via predictions of surface water concentrations based on the concept that a debris flow is similar to a surface water flow, as it is influenced by mountain topography. This study considered urban areas affected by large debris flows or landslides. Digital mapping (including the slope and upslope contributing areas) and the wetness index were used to determine the relevant topographic factors and the hydrology of the area. We determined the hazard susceptibility of debris flow by predicting the surface water concentration based on the topography of the surrounding mountainous terrain. Results obtained using the distinct element method were used to derive a correlation equation between the weight and the impact force of the debris flow. We consider that in using a correlation equation, this method could assist in the effective installation of debris-flow-prevention structures.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.73-79
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• 2008

Economic growth, industrialization and urbanization have made society more vulnerable than ever to seismic hazard in Korea. Although Korea has not experienced severe damage due to earthquakes during the last few decades, there is little doubt of the potential for large earthquakes in Korea as documented in the historical literature. As we see no immediate promise of short-term earthquake prediction with current science and technology, earthquake early warning systems attract more and more attention as a practical measure to mitigate damage from earthquakes. Earthquake early warning systems provide a few seconds to tens of seconds of warning time before the onset of strong ground shaking. To achieve rapid earthquake location, we propose to take full advantage of information from existing seismic networks; by using P wave arrival times at two nearest stations from the earthquake hypocenter and also information that P waves have not yet arrived at other stations. Ten earthquakes in the Korean peninsula and its vicinity are selected for the feasibility study. We observed that location results are not reliable when earthquakes occur outside of the seismic network. Earthquakes inside the seismic network, however, can be located very rapidly for the purpose of earthquake early warning. Seoul metropolitan area may secure $10{\sim}50$ seconds of warning time before any strong shaking starts for certain events. Carefully orchestrated actions during the given warning time should be able to reduce hazard and mitigate damages due to potentially disastrous earthquakes.

• Journal of Korean Society of Disaster and Security
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• v.12 no.3
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• pp.13-24
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• 2019

The concept of shape similarity has been applied to verify the accuracy of the SIND model, the real-time prediction model for disaster risk. However, the CRITIC method, one of the most widely used in geometric methodology, is definitely limited to apply to complex shape such as hazard map for coastal disaster. Therefore, we suggested the modified CRITIC method of which we added the shape factors such as RCCI and TF to consider complicated shapes. The matching pairs were manually divided into exact-matching pairs and mis-matching pairs to evaluate the applicability of the new method for shape similarity into hazard maps for storm surges. And the shape similarity of each matching pair was calculated by changing the weights of each shape factor and criteria. Newly proposed methodology and the calculated weights were applied to the objects of the existent hazard map and the results from SIND model. About 90% of exact-matching pairs had the shape similarity of 0.5 or higher, and about 70% of mis-matching pairs were it below 0.5. As future works, if we would calibrate narrowly and adjust carefully multi-objects corresponding to one object, it would be expected that the shape similarity of the exact-matching pairs will increase overall while it of the mis-matching pairs will decrease.

• Journal of the Korean GEO-environmental Society
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• v.22 no.11
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• pp.5-13
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• 2021

The interest of expecting the liquefaction damage is increasing due to the liquefaction in Pohang in 2017. Liquefaction is defined as a phenomenon that the ground can not support the superstructure due to loss of the strength of the ground. As an alternative against this, many studies are being conducted to increase the precision and to compose a liquefaction hazard map for the purpose of identifying the scale of liquefaction damage using the liquefaction potential index (LPI). In this research, in order to analyze the degree of precision with regard to spatial interpolation objects such as LPI value and geotechnical information for LPI determination, liquefaction hazard map were made for the target area. Furthermore, based on the trend of precision, probability value was analyzed using probability maps prepared through qualitative characteristics. Based on the analysis results, the precision of the liquefaction hazard map setting the spatial interpolation object as geotechnical information is higher than that as LPI value. Furthermore, the precision of the liquefaction hazard map does not affect the distribution of the probability value.

• Journal of the Korea Society for Simulation
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• v.30 no.2
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• pp.49-64
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• 2021

M&S techniques are widely used as scientific means to systematically develop response plans to chemical and biological (CB) hazards. However, while the theoretical area of hazard dispersion modeling has achieved remarkable practical results, the operational analysis area to simulate CB hazard response plans is still in an early stage. This paper presents a model to simulate CB hazard response plans such as detection, protection, and decontamination. First, we present a possible way to display high-fidelity hazard dispersion in a combat simulation model, taking into account weather and terrain conditions. We then develop an improved vulnerability model of the combat simulation model, in order to simulate CB damage of combat simulation entities based on other casualty prediction techniques. In addition, we implement tactical behavior task models that simulate CB hazard response plans such as detection, reconnaissance, protection, and decontamination. Finally, we explore its feasibility by analyzing contamination detection effects by distributed CB detectors and decontamination effects according to the size of the {contaminated, decontamination} unit. We expect that the proposed model will be partially utilized in disaster prevention and simulation training area as well as analysis of combat effectiveness analysis of CB protection system and its operational concepts in the military area.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1497-1501
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• 2005

Branch instructions which make the sequential instruction flow changed cause pipeline stalls in microprocessor. The pipeline hazard due to branch instructions are the most serious problem that degrades the performance of microprocessors. Branch target buffer predicts whether a branch will be taken or not and supplies the address of the next instruction on the basis of that prediction. If the hanch target buffer predicts correctly, the instruction flow will not be stalled. This leads to the better performance of microprocessor. In this paper, the architecture of a ta8 memory that branch target buffer and TLB can share is presented. Because the two tag memories used for branch target buffer and TLB each is replaced by single combined tag memory, we can expect the smaller chip size and the faster prediction. This shared tag architecture is more advantageous for the microprocessors that uses more bits of address and exploits much more instruction level parallelism.

• Earthquakes and Structures
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• v.11 no.5
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• pp.779-807
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• 2016

Ground Motion Prediction Equations (GMPEs) are essential tools in seismic hazard analysis. With the introduction of probabilistic approaches for the estimation of seismic response of structures, also known as, performance based earthquake engineering framework; new tasks are defined for response spectrum such as the reference criterion for effective structure-specific selection of ground motions for nonlinear time history analysis. One of the recent efforts to introduce a high quality databank of ground motions besides the corresponding selection scheme based on the broadband spectral consistency is the development of SIMBAD (Selected Input Motions for displacement-Based Assessment and Design), which is designed to improve the reliability of spectral values at all natural periods by removing noise with modern proposed approaches. In this paper, a new global GMPE is proposed by using selected ground motions from SIMBAD to improve the reliability of computed spectral shape indicators. To determine regression coefficients, 204 pairs of horizontal components from 35 earthquakes with magnitude ranging from Mw 5 to Mw 7.1 and epicentral distances lower than 40 km selected from SIMBAD are used. The proposed equation is compared with similar models both qualitatively and quantitatively. After the verification of model by several goodness-of-fit measures, the epsilon values as the spectral shape indicator are computed and the validity of available prediction equations for correlation of the pairs of epsilon values is examined. General consistency between predictions by new model and others, especially, in short periods is confirmed, while, at longer periods, there are meaningful differences between normalized residuals and correlation coefficients between pairs of them estimated by new model and those are computed by other empirical equations. A simple collapse assessment example indicate possible improvement in the correlation between collapse capacity and spectral shape indicators (${\varepsilon}$) up to 20% by selection of a more applicable GMPE for calculation of ${\varepsilon}$.

• Earthquakes and Structures
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• v.6 no.1
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• pp.1-18
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• 2014

The main focus of this paper is the analysis of the different components of the variability for strong ground motions recorded from earthquakes produced by the Vrancea subcrustal seismic source. The analysis is performed for two ground motion prediction equations: Youngs et al. (1997) and Zhao et al. (2006), recommended within the SHARE project for the Vrancea subcrustal seismic source and which are proposed in the work of Delavaud et al. (2012) and graded best in Vacareanu et al. (2013c). The first phase of the analysis procedure consists of a grading procedure. In the second phase, the single station sigma procedure is applied for both attenuation models in order to reduce some parts of ground motion models' variability produced by the ergodic assumption. The strong ground motion database which is used throughout the study consists of over 400 accelerograms recorded from 9 Vrancea intermediate-depth seismic events. The results of the single station sigma analysis show significant reduction of the standard deviations, especially in the case of the Youngs et al. (1997) attenuation model, which is also graded better than the other selected GMPE.

• Korea Journal of Hospital Management
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• v.6 no.2
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• pp.22-36
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• 2001

The hospital bankruptcy rate is increasing, therefore it is very important to predict the bankruptcy using the existing hospital management information. The hospital bankruptcy is often measured in year intervals, called grouped duration data, not by the continuous time elapsed to the bankruptcy. This study introduces a hierarchical generalized linear model(HGLM) for analysis of hospital bankruptcy data. The hazard function for each hospital may be influenced by unobservable latent variables, and these unknown variables are usually termed as random effects or frailties which explain correlations among repeated measures of the same hospital and describe individual heterogeneities of hospitals. Practically, the data of twenty bankrupt and sixty profitable hospitals were collected for five years, and were fitted to HGLM. The results were compared with those of the logit model. While the logit model resulted only in the effects of explanatory variables on the bankruptcy status at specific period, the HGLM showed variables with significant effects over all observed years. It is concluded that the HGLM with a fixed ratio and a period of total asset turnrounds was justified, and could find significant within and between hospital variations.