• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.129-130
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• 2023

The From COVID-19 until recently, the demand for hiking has been rapidly increasing due to the popularization of mountain seekers.,On weekends and holidays, people who do not hike frequently while hiking in large and small mountains to see wildflowers and foliage in the mountains are more likely to be exposed to safety accidents due to an increase in sudden muscle use.,If you fall or get muscle damage during a hike, you can prevent a major accident with a simple treatment. In some cases, the error of first aid may permanently damage the important function of the body.,In particular, during a safety accident on a mountain, while climbing in light clothes, the body temperature rises due to the sweat that was shed at the beginning, and the blood pressure rises due to the contraction of the blood vessels due to the drop in body temperature from the top, resulting in an emergency such as cardiac arrest.,According to statistics from the National Park Service, nearly half (48%) of deaths in national parks are known to be sudden cardiac deaths.,There are many safety accidents that occur frequently in the mountains, but among them, we will study how to cope with acute diseases such as cardiac arrest due to increased blood pressure due to insufficient body temperature control, chest pain or dyspnea, and heart burden due to excessive hiking.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.3
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• pp.117-123
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• 2016

One of the major characteristics of the swell-like high waves, which occur in the East Sea mostly in winter with large height and long period, is its suddenness associated with the rapid development of high waves from a calm state of sea. To represent such suddenness, in this study, the term sudden high waves is introduced. To propose the criterion of sudden high waves, comparisons were made between the wave measurement data at Gangneung and Wangdolcho for eight years from 2005 and the record of marine accidents and property damage on the coast of Gangwon-do Province and Gyeongsangbuk-do Province during the same period. It was found that most of the accidents occurred when ${\Delta}(H^2L)/{\Delta}t$ was approximately greater than the top 20% or $88.6m^3/hr$, which is therefore proposed as the criterion of sudden high waves. The used variable represents the rate of increase of the wave energy in one wavelength, including not only height and period but also suddenness of high waves.

• Journal of Korea Water Resources Association
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• v.49 no.9
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• pp.749-759
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• 2016

The aim of this study is to apply and to evaluate the radar-based risk prediction algorithm for damage reduction by sudden localized heavy rain in urban areas. The algorithm is combined with three processes such as "detection of cumulonimbus convective cells that can cause a sudden downpour", "automatic tracking of the detected convective cells", and "risk prediction by considering the possibility of sudden downpour". This algorithm was applied to rain events that people were marooned in small urban stream. As the results, the convective cells were detected through this algorithm in advance and it showed that it is possible to determine the risk of the phenomenon of developing into local heavy rain. When use this risk predicted results for flood prevention operation, it is able to secure the evacuation time in small streams and be able to reduce the casualties.

• Structural Engineering and Mechanics
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• v.50 no.2
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• pp.241-255
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• 2014

The girder of self-anchored suspension bridge is subjected to large compression force applied by main cables. So, serious damage of the girder due to breakage of hangers may cause collapse of the whole bridge. With the time increasing, the hangers may break suddenly for their resistance capacities decrease due to corrosion. Using nonlinear static and dynamic analysis methods and adopting 3D finite element model, the responses of a concrete self-anchored suspension bridge to sudden breakage of hangers are studied in this paper. The results show that the sudden breakage of a hanger has significant effects on tensions of the hangers next to the broken hanger, bending and torsion moments of the girder, moments of the towers and reaction forces of the bearings. The results obtained from dynamic analysis method are very different from those obtained from static analysis method. The maximum tension of hanger produced by breakage of a hanger exceeds 2.2 times of its initial value, the maximum dynamic amplification factor reaches 2.54, which is larger than the value of 2.0 recommended for cable-stayed bridge in PTI codes. If two adjacent hangers on the same side of bridge break one after another, the maximum tension of other hangers exceeds 3.0 times of its initial value. If the safety factor adopted to design hanger is too small, or the hangers have been exposed to corrosion, the bridge may collapse due to breakage of two adjacent hangers.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.818-823
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• 2012

In order to predict necking behaviour of aluminium sheets, a crystal plasticity model is introduced in the finite element analysis of tensile test. Due to the computational limits of time and memory, only a small part of tensile specimen is subjected to the analysis. Grains having different orientations are subjected to numerical tensile tests and each grain is discretized by many elements. In order to predict the sudden drop of load carrying capacity after necking, a well-known Cockcroft-Latham damage model is introduced. The mismatch of grain orientation causes stress concentration at several points and damage is evolved at these points. This phenomenon is similar to void nucleation. In the same way, void growth and void coalescence behaviours are well predicted in the analysis. For the comparison of prediction capability of necking, same model is subjected to finite element analysis using uniform material properties of polycrystal with and without damage. As a result, it is shown that the crystal plasticity model can be used in prediction of necking and fracture behavior of materials accurately.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.221-226
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• 1994

A safety evaluation of cable tunnel, which is a concrete box structure with telecommunication facilities in it, exposed to fire is given. The immediate field observation was performed to find out any sign of sudden structural failure. In some region, where the fire intensity was heavy, the spalling of concrete cover in upper slab occurred. Next, more careful investigation was done with proper non-desturctive testing methods and structural analysis taking into account the changes in material properties due to fire. It seems that there is no severe damage on concrete, reinforcements and over all structural system.

• Smart Structures and Systems
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• v.5 no.4
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• pp.369-379
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• 2009

The sudden collapse of Interstate 35 Bridge in Minneapolis gave a wake-up call to US municipalities to re-evaluate aging bridges. In this situation, structural health monitoring (SHM) technology can provide the essential help needed for monitoring and maintaining the nation's infrastructure. Monitoring long span bridges such as cable-stayed bridges effectively requires the use of a large number of sensors. In this article, we introduce a probabilistic approach to identify optimal locations of sensors to enhance damage detection. Probability distribution functions are established using an artificial neural network trained using a priori knowledge of damage locations. The optimal number of sensors is identified using multi-objective optimization that simultaneously considers information entropy and sensor cost-objective functions. Luling Bridge, a cable-stayed bridge over the Mississippi River, is selected as a case study to demonstrate the efficiency of the proposed approach.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.52-58
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• 2015

As sudden rainfall has happened, the debris flow has occurred in the mountain area. Recently sudden rainfall occurred so frequently caused by abnormal climate. Thus debris flow hazard had consecutively increased damage because of debris flow. Recently, Enormous damage due to debris flow have occurred in Korea. Various studies have been conducted to prevent search debris flow hazard. This study was carried out for debris flow behavior according to the land slope on propagation. It is the important one among factors that are related to the propagation over the city with respect to debris flow discharge and depth. For the numerical simulations in this study, the land slope was varied of 5, 0, $-5^{\circ}$ to investigate the debris flow behavior with the FLO-2D, often recommended by FEMA to simulate debris flow. To verify the performance of FLO-2D, comparison with the USGS experiments (Iverson et al, 2010) was conducted. From numerical results the propagation length of the debris flow was found the most sensitive one. Maximum of debris flow thickness and velocity and structural vulnerabilities were investigated to the effect of land slope. They was became smaller according to land slope of 5, -5, $0^{\circ}$ in the order. As a result, debris flow behavior analysis about the effect of the land slope could contribute to understand the vulnerability of city for debris flow hazards.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.4
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• pp.233-242
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• 2023

The unscented Kalman filter (UKF), which is widely used to estimate the states of nonlinear dynamic systems, can be improved to realize robust system identification by using multiple sigma-point sets. When using Kalman filter methods for system identification, artificial noises must be appropriately selected to achieve optimal estimation performance. Additionally, an appropriate scaling factor for the sigma-points must be selected to capture the nonlinearity of the state-space model. This study entailed the use of Bouc-Wen hysteresis model to examine the nonlinear behavior of a single-degree-of-freedom oscillator. On the basis of the effects of the selected artificial noises and scaling factor, a new UKF method using multiple sigma-point sets was devised for improved robustness of the estimation over various signal-to-noise-ratio values. The results demonstrate that the proposed method can accurately track nonlinear system states even when the measurement noise levels are high, while being robust to the selection of artificial noise levels.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.53-60
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• 1989

The results of the investigation on the effects of plant nutrio-physiological status and reemergence of sudden wilting in rice on the occurrence of sudden wilting were summarized as follows: 1. The occurrence of sudden wilting, degree of damage and occurring time in the investigated variety showed to concur with the results of the previous experiment. 2. Nitrogen and Potassium contents in leaves related an occurrence of sudden wilting at heading stage have a very high negative co-relation (the value is -0.9224 at Yushin and -0.8243 at Milyang 23). 3. Regarding the relation between occurrence of sudden wilting and root activity capacity at the late growth stage, the root activity capacity at productive growth stage showed higher than at reproductive growth stage, which is the same in the two varieties but Milyang 23 is higher than Yushin. It is confirmed that root activity capacity in the two varieties has become very low at reproductive growth stage. 4. The toot activity capacity in the field with potassium showed a small occurrence of sudden wilting and the root activity capacity in the field with no potassium showed a very high co-relation value (the value is 0.8947 at Yushin and 0.7301 at Milyang 23). 5. Regarding the relation between the occurrence of sudden wilting and water evaporation quantity, water evaporation quantity after the heading date has a more direct relation to sudden wilting than that which occurrs prior to the heading date. Water evaporation quantity is higher in the field with no potassium, low leaves and Yushin, than in the field with potassium high leaves and Milyang 23. 6. The starch content in culm of Yushin and Milyang 23 at ripening stage showed high value in proportion to potassium quantity, and the starch content is lower as internode is lower. However, in fourth internode, the starch content is greatly increased in the field with potassium contrasted to the field with no potassium.