• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.569-577
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• 2015

The aim of this study is to qualitatively evaluate the cracking control effects of expansive concrete used in reinforced concrete building. The result of experiments in laboratory shows that autogenous shrinkage and drying shrinkage are suppressed by using expansive additive. The tensile stress-strength ratio is lower in expansive concrete than normal concrete under fully restrained condition. Compression stress could be effectively generated in early age in the walls in buildings by the use of expansive additive, and tensile stress due to drying shrinkage at later age eventually decreased. Additionally, visual observation at long-term ages shows that the cracking area of expansive concrete was approximately 35% of normal concrete, which confirms that the use of expansive additive reduces concrete cracking in reinforced concrete buildings.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.5
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• pp.1027-1041
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• 2015

Recently, there are rapidly increasing cases of APT (Advanced Persistent Threat) attacks such as Verizon(2010), Nonghyup(2011), SK Communications(2011), and 3.20 Cyber Terror(2013), which cause leak of confidential information and tremendous damage to valuable assets without being noticed. Several anomaly detection technologies were studied to defend the APT attacks, mostly focusing on detection of obvious anomalies based on known malicious codes' signature. However, they are limited in detecting APT attacks and suffering from high false-negative detection accuracy because APT attacks consistently use zero-day vulnerabilities and have long latent period. Detecting APT attacks requires long-term analysis of data from a diverse set of sources collected over the long time, real-time analysis of the ingested data, and correlation analysis of individual attacks. However, traditional security systems lack sophisticated analytic capabilities, compute power, and agility. In this paper, we propose a Fast Data based real-time abnormal behavior detection system to overcome the traditional systems' real-time processing and analysis limitation.

• Journal of the Korean GEO-environmental Society
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• v.17 no.11
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• pp.23-33
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• 2016

This study evaluated the stability and deformation subsea foundation after implementation of the contaminant isolation method by covering the contaminated materials using Zeolite and sands under subsea condition. The appropriate contaminant adsorption materials used in this study was selected as Zeolite based on the existing research results due to its efficiency. Safety (or stability) was evaluated by calculation and to analyze deformation after completing the contaminant isolation method. The minimum safety factors from slope stability analyses results were 30.1 and 11.2 depending on subsea submerged conditions and the amount of the maximum primary consolidation settlement from consolidation analysis results was 209.2 mm. In addition, change of consolidation amount with increasing consolidation time was evaluated based on consolidation degree.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1B
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• pp.53-57
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• 2012

This study presents a numerical model that is capable of simulating the evolution of mining pit in a stream. The numerical model is based on the quasi-steady assumption that the flow is steady with time-dependent morphological change. This hypothesis is valid due to the fact that the stream morphology changes over a long period compared with the time of flow change. Before applications, numerical experiments are carried out with two total load formulas such as Engelund and Hansen's (1967) and Ackers and White's (1973). It is found that the use of Engelund and Hansen's formula reproduces evolution of mining pit best compared with simulated profiles in Parker (2004). Then, the model is applied to two laboratory experiments in the literature. In general, the numerical model simulates properly the evolution of mining pit in laboratory open-channels. However, it is found that the model does not reproduce head-cutting, propagating upstream, and under-estimates the wave of the bed, propagating downstream, after finishing the re-fill of the mining pit.

• Journal of Korean Society of societal Security
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• v.1 no.2
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• pp.61-66
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• 2008

More than 70% of Korea consists of mountainous area and during the construction of roads and railroads many cut-slopes are inevitably formed. A number of environmental factors, such as the rainy season and frost heave during winter/thaw during spring, can result in rock falls and landslides. The failure of slopes is increasing every year and can cause damage to vehicles, personal injury and even fatality. In order to help protect people and property, there is a need for real-time monitoring systems to detect the early stages of slope failures. In this respect, the GMG has been using Translation Rotation Settlement (TRS) sensor units installed on slopes to monitor movement in real-time. However, the data lines of this system are vulnerable and the whole system can be damaged by a single lightning strike. In order to overcome this, GMG have proposed the use of Ubiquitous Sensor Networks (USN). The adoption of a USN system in lieu of data cables can help to minimize the risk of lightning damage and improve the reliability of slope monitoring systems.

• Korean Journal of Remote Sensing
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• v.36 no.5_4
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• pp.1231-1244
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• 2020

Landsat satellites are representative optical satellites that have observed the Earth's surface for a long-term, and are suitable for long-term changes such as disaster preparedness/recovery monitoring, land use change, change detection, and time series monitoring. In this paper, clouds and cloud shadows were detected using QA bands to detect and remove clouds simply and efficiently. Then, the missing area of the experimantal image is restorated through the SSG algorithm, which does not directly refer to the pixel value of the reference image, but performs restoration to the pixel value in the Experimental image. Through this study, we presented the possibility of utilizing the modified SSG algorithm by quantitatively and qualitatively evaluating information on variousl and cover conditions in the thermal wavelength band as well as the visible wavelength band observing the surface.

• Journal of Ginseng Research
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• v.33 no.1
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• pp.1-7
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• 2009

Clinical and animal studies have shown that free radical overload is an important cause for a variety of diseases. Although ginseng has been recognized as antioxidant, how it modulates anti-oxidative process at the molecular level remains unknown. Free radical production is induced by tumor necrosis factor-$\alpha$ (TNF-$\alpha$) under the stress condition, and (TNF-$\alpha$) release is activated by TNF-$\alpha$-converting enzyme (TACE). Since TACE inhibitor is also well known for anti-inflammatory agent, ginseng seems to show anti-oxidative activity by repressing TACE pathway. Further studies on signal transduction would be warranted to elucidate molecular action mechanisms of ginseng on anti-oxidation and anti-inflammation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.277-283
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• 2016

A high-precision force-feedback 3-axes accelerometer developed in Korea has been investigated and studied for the verification of feasibility in the computational analysis and health monitoring of civil infrastructures. Through a series of experiment, the nonlinearity, bandwidth, low-frequency signal measurement accuracy and bias characteristics of the accelerometer has been thoroughly compared to those of two accelerometers produced by two market leaders in domestic and global accelerometer market. The experiment results shows that the overall measurement performance of the accelerometer has superiority over the performance of the two accelerometers from global market leader companies. Especially, the accelerometer shows a better low-frequency signal measurement accuracy and constant bias characteristic, which are mostly required in the computational analysis and the long-term health monitoring of large-scale civil infrastructures.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.165-173
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• 2020

ABS and PLA are applied for restoring missing part of damaged ceramics, but are not similar to the material of ceramics, so this study conducted a research on the properties and applicability of ceramic resin. This study conducted actual restoration of ABS and ceramic resin as well as cast restoration method with experiment of properties. Results show that manufacturing of restored part showed higher precision than existing materials, which enables printing of tiny shapes showing excellent surface texture and gloss than L30 and ABS resin. As a result of measuring properties, the material showed excellent durability than existing materials with no contraction and deformation and compressive strength, but value of specific gravity and hardness can lower processability after manufacturing. Long-term monitoring, evaluation of reliability of ceramic resin applied in this study, additional researches on the restorability of the original shape when printing too thin or long restored part are needed.

• Journal of Ocean Engineering and Technology
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• v.28 no.2
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• pp.133-139
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• 2014

Offshore wind turbines have been constructed extensively throughout the world. These turbines are subjected to approximately $10^8$ horizontal load cycles produced from wind, waves, and current during their lifetimes. Therefore, the accumulated displacement of the foundation under horizontal cyclic loading has significant effects on the foundation design of a wind turbine. Akili(2006) and Achmus et al.(2009) performed cyclic triaxial tests on dry sands and proposed an empirical model for predicting the accumulated plastic strain of sands under long-term cyclic loading. In this study, cyclic triaxial tests were performed to analyze the cyclic loading behaviors of dry sands. A total of 27 test cases were performed by varying three parameters: the relative density of the sands, cyclic load level, and confining stress. The test results showed that the accumulated plastic strain increased with an increase in the cyclic load level and a decrease in the relative density of the sand. The confining stress had less effect on the plastic strain. In addition, the plastic strain at the 1st loading cycle was about 57% of the accumulated strain at 1,000 cycles. Finally, the input parameters of the empirical models of Akili(2006) and Achmus et al.(2009) were evaluated by using the relative density of the sand and the cyclic load level.