• Smart Structures and Systems
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• v.15 no.6
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• pp.1583-1600
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• 2015

When natural disasters occur, including earthquakes, tsunamis, and debris flows, they are often accompanied by various types of damages such as the collapse of buildings, broken bridges and roads, and the destruction of natural scenery. Natural disaster detection and warning is an important issue which could help to reduce the incidence of serious damage to life and property as well as provide information for search and rescue afterwards. In this study, we propose a novel computer vision technique for debris flow detection which is feature-based that can be used to construct a debris flow event warning system. The landscape is composed of various elements, including trees, rocks, and buildings which are characterized by their features, shapes, positions, and colors. Unlike the traditional methods, our analysis relies on changes in the natural scenery which influence changes to the features. The "background module" and "monitoring module" procedures are designed and used to detect debris flows and construct an event warning system. The multi-criteria decision-making method used to construct an event warring system includes gradient information and the percentage of variation of the features. To prove the feasibility of the proposed method for detecting debris flows, some real cases of debris flows are analyzed. The natural environment is simulated and an event warning system is constructed to warn of debris flows. Debris flows are successfully detected using these two procedures, by analyzing the variation in the detected features and the matched feature. The feasibility of the event warning system is proven using the simulation method. Therefore, the feature based method is found to be useful for detecting debris flows and the event warning system is triggered when debris flows occur.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.4
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• pp.10-21
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• 2001

This paper develops a logical simulation method for by dyversity of situations. Most existing systems, for example, games and infant tutoring systems lead users to virtual environment with unfolding situations, but are not designed to induce the change of the environment itself. In this paper, a logically simulated environment is created by defining situations and single events based on situation hierarchy structure. We elaborate the occurrence of events by classifying the causality. The occurrence or natural phenomena is dictated by physical laws and natural phenomena are expressed as the transition of the event based on event association. Specifically we define the source of the event for natural phenomena and we consider the existence of objects as a primary factor in event occurrence. The advantages of this approach include the reuse of events, that is, different events can be generated in the same flow with fresh conditions. This allows us to implement a more practical and logical environment. A drawback to this method is the difficulty in dividing a situation into events. The proposed method was implemented in the context of the change of season among natural phenomena.

• Nuclear Engineering and Technology
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• v.49 no.2
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• pp.395-403
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• 2017

An efficient evaluation method for the probability of a tornado missile strike without using the Monte Carlo method is proposed in this paper. A major part of the proposed probability evaluation is based on numerical results computed using an in-house code, Tornado-borne missile analysis code, which enables us to evaluate the liftoff and flight behaviors of unconstrained objects on the ground driven by a tornado. Using the Tornado-borne missile analysis code, we can obtain a stochastic correlation between local wind speed and flight distance of each object, and this stochastic correlation is used to evaluate the conditional strike probability, $Q_V(r)$, of a missile located at position r, where the local wind speed is V. In contrast, the annual exceedance probability of local wind speed, which can be computed using a tornado hazard analysis code, is used to derive the probability density function, p(V). Then, we finally obtain the annual probability of tornado missile strike on a structure with the convolutional integration of product of $Q_V(r)$ and p(V) over V. The evaluation method is applied to a simple problem to qualitatively confirm the validity, and to quantitatively verify the results for two extreme cases in which an object is located just in the vicinity of or far away from the structure.

• 한국지구물리탐사학회:학술대회논문집
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• 2011.10a
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• pp.119-122
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• 2011

• Korean Journal of Cognitive Science
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• v.10 no.1
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• pp.45-55
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• 1999

This paper argues that the basic modes of spatial cognition can be best identified in terms of argument/participant location, and shows that natural language uses‘simple’types of semantic denotations to encode spatial cognition, and further notes that spatial expressions should be interpreted not as locating an event/state as a whole but as locating arguments/participants of the event. The ways of locating events/states are identified in terms of argument orientation(AO), Which indicates semantic patterns of linkiarticipant location. and shows that natural langrage uses ng locatives to specific arguments. Four patterns of argument orientation described here reveal substantial modes of spatial cognition. and the AO patterns are mostly determined by the semantic classes of English verbs combining with locative expressions, i.e., by the event type of the predicate. As for the denotational constraint of locatives, the paper concludes that semantic denotations of locative PPs are restricted to the intersecting functions mapping relations to relations.

• Journal of Astronomy and Space Sciences
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• v.20 no.2
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• pp.95-100
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• 2003

This paper is for the investigation of the relationship between the geomagnetic disturbances and the relativistic electron events occurring at geosynchronous orbit. We have analyzed the electron fluxes of E > 2 MeV measured by GOES 10 satellite and the hourly Dst index for the period of April, 1999 to December, 2002. With the rigorous definition of the relativistic event, total 34 events were identified during the time period. Our statistical study showed that more than 50% of the total events occurred associated with weak (or sometimes virtually no) magnetic storms. And only ~ 20% of the events took place accompanied by a strong magnetic storm of $Dst_{min}$ < -100 nT. This result suggests that large geomagnetic storms may not be crucial for the occurrence of a relativistic event at geosynchronous orbit. We also found that there is no clear correlation between the maximum electron flux of an event and the associated minimum of Dst. Therefore any study on the physical mechanism (s) accounting for the relativistic events should take it into account that strong magnetic storms may not be necessarily required for the occurrence of a relativistic electron event at geosynchronous orbit.

• Earthquakes and Structures
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• v.7 no.4
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• pp.449-462
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• 2014

Seismically induced structural damage, as well as any damage caused by a natural catastrophic event, covers a wide area. This suggests to supervise the event consequences by vision tools. This paper reports the evolution from the results obtained by the project RADATT (RApid Damage Assessment Telematics Tool) funded by the European Commission within FP4. The aim was to supply a rapid and reliable damage detector/estimator for an area where a catastrophic event had occurred. Here, a general open-source methodology for the detection and the estimation of the damage caused by natural catastrophes is developed. The suitable available hazard and vulnerability data and satellite pictures covering the area of interest represent the required bits of information for updated telematics tools able to manage it. As a result the global damage is detected by the simple use of open source software. A case-study to a highly dense agglomerate of buildings is discussed in order to provide the main details of the proposed methodology.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2375-2387
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• 2024

The passive safety systems (PSSs) within water-cooled reactors are meticulously engineered to function autonomously, requiring no external power source or manual intervention. They depend exclusively on inherent natural forces and the fundamental principles of reactor physics, such as gravity, natural convection, and phase changes, to manage, alleviate, and avert the release of radioactive materials into the environment during accident scenarios like a loss-of-coolant accident (LOCA). PSSs are already integrated into such operating commercial reactors as the Advanced Pressurized Reactor-1000 MWe (AP1000) and the Water-Water Energetic Reactor-1200 MWe (WWER-1200) are adopted in most of the upcoming small modular reactor (SMR) designs. Examples of water-cooled SMR PSSs are the passive emergency core-cooling system (ECCS), passive containment cooling system (PCCS), and passive decay-heat removal system, the designs of which vary based on reactor system-design requirements. However, understanding the accident-event progression and phases of a LOCA is pivotal for adopting a specific PSS for a new SMR design. This study covers the accident-event progression for direct vessel injection (DVI) small-break loss-of-coolant accident (SB-LOCA), associated physics phenomena, knowledge gaps, and important figures of merit (FOMs) that may need to be evaluated and assessed to validate thermal-hydraulics models with an available experimental dataset to support new SMR design and development.

• Korea Trade Review
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• v.45 no.3
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• pp.21-33
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• 2020

This study aims to determine if the current COVID-19 event can be admitted as an excuse for non-performance in international trade transactions. In order to do so, this study selected case study method in the analysis. Firstly, the definitions of Force Majeure addressed in CISG, UCC, Chinese Law, and Korean Law were organized. Secondly, this study reviewed the avian influenza event in 2006 and the natural disaster event occurred in Guangdong, China, in 2017. In the study, three critical evaluation factors are suggested in order to be admitted as a Force Majeure event in international transactions as following: 1) possibility of foresight of the event, 2) possibility to overcome and avoid the event, and 3) the enterprise's countermeasures of the event. As an implication, this study organized the definitions of Force Majeure that were indicated in various kinds of Laws and suggested the basic framework to analyze the possibility of admittance as a Force Majeure event.

• Journal of the Korean Society of Safety
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• v.37 no.1
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• pp.1-11
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• 2022

This numerical study investigates the effects of the size of the natural smoke vent area (10% and 1% of the floor area) and the location of the fire source (i.e., at the side and center of the stage) on the temperature distribution in the compartment and velocity distribution and mass flow rate of flow through a natural smoke vent for a reduced-scale model of a theater stage. Then, the mass flow rate of outflow through the natural smoke vent in the event of a fire for a real-scale theater stage was examined. The case with the larger natural smoke vent area and central fire source location showed lower temperature distributions and higher mass flow rates of outflow and inflow than the case with the smaller natural smoke vent area and side fire source location. The trends of the temperature distributions were closely related to those of the mass flow rates for the outflow and inflow. Additionally, the case with the larger natural smoke vent area and central fire source location exhibited the most non-uniform flow velocity distribution in all cases tested. A bidirectional flow, in which the outflow and inflow occur simultaneously, was observed through the natural smoke vent. In the event of a fire situation in a real-scale theater stage, it was predicted that the case with the larger natural smoke vent area and central fire source location would have a mass flow rate of outflow that is 43.53 times higher than that of the case with the smaller natural smoke vent area and side fire source location. The present results indicate that the natural smoke vent location should be determined by considering the location in a theater stage where a fire can occur.