• Journal of Korea Multimedia Society
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• v.17 no.9
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• pp.1098-1103
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• 2014

Smartphone is very much ingrained into our lives and it has propagated rapidly. With the growing expansion of smartphone, the number of lost smartphones has proliferated all the while. Unlike common personal belongings, smartphone is a high-priced goods and has personal information. In case it gets lost or stolen, it will cause monetary damage as well as secondary damage of personal information leaks. To lesson the damage, diverse applications that prevent the loss of a smartphone have been developed. But existing applications place emphasis on providing countermeasures that tracks the missing smartphones. Therefore, this paper describes the design and implementation of a smartphone application which provides precautionary functions to prevent the loss of a smartphone and countermeasures to track the missing smartphone. The implemented application prevents the loss of a smartphone using satefy zone and movement detection. In the event we lose a smartphone, it helps us recover a lost property using location tracking and remote control functions quickly and efficiently.

• Smart Structures and Systems
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• v.30 no.6
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• pp.673-686
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• 2022

Deep learning algorithms for Structural Health Monitoring (SHM) have been extracting the interest of researchers and engineers. These algorithms commonly used loss functions and evaluation indices like the mean square error (MSE) which were not originally designed for SHM problems. An updated loss function which was specifically constructed for deep-learning-based structural damage detection problems has been proposed in this study. By tuning the coefficients of the loss function, the weights for damage localization and quantification can be adapted to the real situation and the deep learning network can avoid unnecessary iterations on damage localization and focus on the damage severity identification. To prove efficiency of the proposed method, structural damage detection using convolutional neural networks (CNNs) was conducted on a truss bridge model. Results showed that the validation curve with the updated loss function converged faster than the traditional MSE. Data augmentation was conducted to improve the anti-noise ability of the proposed method. For reducing the training time, the normalized modal strain energy change (NMSEC) was extracted, and the principal component analysis (PCA) was adopted for dimension reduction. The results showed that the training time was reduced by 90% and the damage identification accuracy could also have a slight increase. Furthermore, the effect of different modes and elements on the training dataset was also analyzed. The proposed method could greatly improve the performance for structural damage detection on both the training time and detection accuracy.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.262-270
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• 2018

Purpose: This paper investigates and analyzes the loss and damage ratio of maintenance monitoring sensor in metropolitan and high speed railroad tunnel in Korea and abroad. Method: After 5~6 years from the installation, the maintenance monitoring sensor on metropolitan transit tunnels showed the loss and damage ratio from 14.2% to 14.8% in Seoul metro line no. 5, 6, 7, 9, and 13.9% in UK channel tunnel. Based on the result, 15% is thought to be a proper set for the elapsed years, which is 5 years from the installation. Results: The maintenance monitoring sensor on high speed railroad tunnels showed the loss and damage ratio of 60.9% in Ho-Nam high speed railroad on 1 stage after 3 ~ 5 years from the installation, which was approximately 4 times as high as that of Seoul metro line no. 5, 6, 7, 9. Conclusion: Kyung-Bu high speed railroad on 2 stage, after 8~10 years from the installation, showed the loss and damage ratio of 66.8%. Based on the result, it can be inferred that the loss and damage ratio increases drastically after 5~10 years from the installation. Therefore, it is necessary to study on the loss and damage ratio of long term elapsed years, especially more than 10 years from the installation.

• Earthquakes and Structures
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• v.24 no.2
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• pp.81-90
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• 2023

The maximum drifts are important to the seismic evaluation of steel buildings and connections, but the information can hardly be obtained from the post-earthquake field investigation. This research studies the feasibility of using the loss rate of bolt pretension as an earthquake damage predictor. Full-scale tests were made on four steel connections using bolted-web-welded-flange details. One connection was unreinforced (UN), another was reinforced with double shear plates (DS), and the other two used reduced beam sections (RBS). The preinstalled strain gauges were used to control the pretensions and monitor the losses of the high-strength bolts. The results showed that the loss rate of bolt pretension was highly related to the damage of the connections. The pretensions lost up to 10% in all the connections at the yield drifts of 0.5% to 1%. After yielding of the connections, the pretensions lost significantly until fracture occurred. The UN and DS connections failed with a maximum drift of 4 %, and the two RBS connections showed better ductility and failed with a maximum drift of 6%. Under the far-field-type loading protocol, the loss rate grew to 60%. On the contrary, the rate for the specimen under near-fault-type loading protocol was about 40%. The loss rate of bolt pretension is therefore recommended to use as an earthquake damage predictor. Additionally, the 10% and 40% loss rates are recommended to predict the limit states of connection yielding and maximum strength, respectively, and to define the performance levels of serviceability and life-safety for the buildings.

• Journal of Environmental Health Sciences
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• v.37 no.3
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• pp.173-181
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• 2011

Koo-ni Firing Range in Maehyang-ri consisted of a firing range around 'Nong-sum' and a land-based firing range in the nearby coastal area. From 1951, when the US Air Force began field firing, residents of Maehyang-ri suffered damage to health, environment, life and property due to 54 years of field firing and noise. The purpose of this article is to provide an overview of the environmental damage, property loss, and health impairment by reviewing literature and related lawsuits. Environmental damage, the destruction of coastal fisheries and wetlands, would be a result of heavy metal contamination of soil. Fishing restrictions and the confiscation of farmlands caused financial hardship. Errant bombings led to the loss of life and property, including buildings and livestock. As a result, residents repeatedly sued the Republic of Korea for damages. The court decided partially in favor of the plaintiffs. Finally, Koo-ni firing range was closed down in 2005. Through the literature review, it is presumed that the noise caused hearing problems, hypertension, and mental illness. Since earlier studies were confined to a small fragment of the damage, additional studies focused on chronic health hazards are needed.

• Earthquakes and Structures
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• v.9 no.1
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• pp.257-279
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• 2015

The primary objective of this study is to summarize results from previous experimental tests on laboratory specimens of RC/steel frames with masonry infills, in order to develop fragility functions that permit the estimation of damage in typical non-structural components of RC frame buildings, as a function of attained peak interstory drift. The secondary objective is to derive loss functions for such non-structural components, which provide information on the probability of experiencing a certain level of monetary loss when a given damage state is attained. Fragility curves and loss function developed in this study can be directly used within the FEMA P-58 framework for the seismic performance assessment of RC frame buildings with masonry infills.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.86-95
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• 2010

Ground movements during tunnelling have the potential for major impact on nearby buildings, utilities and streets. The impacts on buildings are assessed by linking the magnitude of ground loss at the source of ground loss around tunnel to the lateral and vertical displacements on the ground surface, and then to the lateral strain and angular distortion, and resulting damage in the building. To prevent or mitigate the impacts on nearby buildings, it is important to understand the whole mechanism from tunnelling to building damage. This paper discusses tunneling-induced ground movements and their impacts on nearby buildings, including the importance of the soil-structure interactions. In addition, a building damage criterion, which is based on the state of strain, is presented and discussed in detail and the overall damage assessment procedure is provided for the estimation of tunnelling-induced building damage considering the effect of soil-structure interaction.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.42-49
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• 2011

To achieve the safety management of an industry by using practical consequence analysis, parameters affecting damage area and financial loss by gas release accident were analyzed at pressure vessels containing flammable gas. As a result, the total financial loss cost was largely effected by the business interruption cost, and it was considered for equipment type and materials, process properties, and circumstances. Also, the consequences of the financial loss must be practically used more than the consequences of the damage area in industry.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.411-434
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• 1982

Yield loss of wheat and barley due to meteorological constraints has been analyzed in order to get the basic information, which will lead to the counter-measures for dissemination of agricultural technology and administration. These meteorological damages were analyzed on the results of percentage yield loss and mechanism of damage and the aspects of constraints were explained. The annual yield loss of wheat and barley were 21.7% by meteorological stress: Cold damage, 5.9% ; excessive soil moisture, 5.6% ; lodging, 2.9% ; drought, 3.0% ; disease, 4.3% etc. Those damages by the stresses mentioned above and rain damage were analyzed in relation to the growth stages and the degrees of damage. The predispositions and the growth of wheat and barley to those meteorological stress are also discussed. Varietal resistances of wheat and barley to those stresses were indexed and the physiological and morphological characteristics of these resistant cultivars are described. Cultural practices to minimize the damages were also reviewed.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.2
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• pp.34-40
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• 2003

Ship damage due to maritime casualties lead to marine pollution, loss of life and properties. The maritime casualties come from the rough sea and bad weather condition generally. Therefore the large-scaled casualties will be derived from loss of structural strength and stability due to the progressive flooding and enlargement of damage by the effect of wave and wind. The improvement of damage survivability is very important in maritime safety This paper described the damage survivability assessment system which can be evaluate and improve the ship safety in consideration of loading, sea and damage condition. The components of the system and decision criteria for damage stability and structural safety is established. The ship modeler and behavior analysis program in wave is developed. Finally further research work is also discussed.