• Journal of the Korean Wood Science and Technology
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• v.31 no.3
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• pp.35-41
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• 2003

The mechanical and physical properties of wood are strongly dependent upon the slope of grain. Specially, tensile strength is more severely affected by the slope of grain. Therefore, tension tests were performed on small thin wood samples made from Pinus radiata with varying the slope of grain. Determining the tensile strength for clear thin wood samples the other variabilities associated with material, size, drying, defects, etc were discarded. Slope of grain was measured by the slope of grain indicator and actual slope of grain was also determined by a protractor. Correlation coefficients between machine measured and actual slope of grain for 40 pieces of 2×20 mm, 300 mm long Pinus radiata were 0.84 for wide face measurement. Results also showed that tensile strength and MOE from stress wave tests decreased with increasing the slope of grain. This study did not establish a relationships for tensile strength and MOE from stress wave with slope of grain. However, the trends of MOEs from stress wave test with both slope of grain are agreed well with Hankinson's equation. Predicted tension strength curve by Hankinson's equation was also agreed well with the experimental data over the range from 0 to 13 degrees for slope of grain.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3C
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• pp.167-178
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• 2008

Rainfall-induced slope failures were simulated by seepage and stability analyses for actual slopes of weathered soils. After undisturbed sampling and testing on a specimen of unsaturated conditions, a seepage analysis was performed under actual rainfall and it was found that the pore water pressure increased at the boundary of soil and rock layers. The safety factor of slope stability decreased below 1.0 and the failure of actual slope could be simulated. Under design rainfall intensity, the seepage analysis could not include the effects of the antecedent rainfall and the rainfall duration. Due to these limitations, the safety factor of slope stability resulted in above 1.0, since the hydraulic head of soil layers had not be affected significantly. In the analysis of another slope failure, the parameters of unsaturated conditions were evaluated using artificial neural network (ANN). In the analysis of seepage, the boundary of soil and rock was saturated sufficiently and then the safety factor could be calculated below 1.0. It was found that the failure of actual slope can be simulated by ANN-based estimation.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.60-64
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• 2010

The purpose of this study if to prevent dangerous accident of the overthrow of the tower crane in summer's hurricane. We develop the SMS in order to give automatic alarm system to operator within the dangerous range and to give a information of the exactly slope in the real time. The slope value of the tower crane is compose of direction, pitch by the front and rear, roll by the right and left and synthesis by the its pitch and roll. Especially, the synthesis eliminate the effect of the wall tie or wire bracing. So, this value should correctly indicate the actual slope. In this study, more applying field test should be applied with the SMS. In the future, a more measurement device can be applied to, and be able to feed more alarm criteria for the review of the risk in the field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3C
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• pp.113-120
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• 2012

An actual slope failure was analyzed in residual soils at Jinju. Due to rainfall infiltration, the safety factor decreases in the unsaturated layers, since the effective stress and shear strength decrease. In this study, the effective stress is based on suction stress using soil water retention curve. Unsaturated properties were evaluated on soil water retention curve, hydraulic conductivity and shear strength with samples from the site. After infiltration analysis of unsaturated flow under the actual rainfall, the distribution of pore water pressure could be calculated in the slope layers. In the stress field of finite elements, an elastic analysis calculated total stress distribution in the layers and also shear stresses on the slip surface using elastic model. On the slip surface, suction stress and effective stress evaluated the shear strength. As a result, the factor of safety was calculated due to rainfall, which could simulate the actual slope failure. In particular, it was found that the suction stress increases and both the effective stress and the shear strength decrease simultaneously on the slip surface.

• Economic and Environmental Geology
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• v.48 no.5
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• pp.379-390
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• 2015

Multibeam backscatter strength is dependent not only on seafloor sediment facies but also on changed incidence angle due to the actual bottom slope. Therefore, the correction for actual bottom slope should be considered before the analysis of backscatter strength. This paper demonstrates the backscatter correction technique for the actual incidence angle and ensonified area. The target area is a part of the eastern Yellow Sea with water depths of 46~55 m. The area is located between the sand ridges and covered by large dunes with various bottom slopes. The dunes usually have the gentle slopes of about $1{\sim}3^{\circ}$, but show some steep slopes of $5{\sim}15^{\circ}$ on the crest. The backscatter strength values on the crest range from -34 to -23 dB, assuming that the bottom is flat. However, this study shows that the backscatter strength range was somewhat reduced (-32~-25 dB) after correction for actual bottom slope. In addition, the backscatter imagery was significantly improved; high and low backscatter strength values on the crest due to the actual bottom slope were normalized. The results demonstrate that the correction technique in this study is an effective tool for processing backscatter strength.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.77-85
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• 2013

Unsaturated slopes experience infiltration during rainfall and become unstable when saturated. On the viewpoint of unsaturated effective stress, as matric suction decreases, both effective stress and shear strength decrease, which declines slope stability consequently. This study is focused on describing effective stress based on suction stress. The actual slope failures are simulated to calculate factors of safety in the field of finite element stress. In the residual soils of Hadong and Pohang, unsaturated properties are evaluated by laboratory tests. For unsaturated slopes, analyses of infiltration, stress and stability were performed to simulate actual failures. Based on unsaturated effective stress principle, the stability of actual slopes could be evaluated successfully. It is verified for the effective stress concept to be applicable to the engineering practice on slope design which considers infiltration by rainfall.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.681-686
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• 2006

This study is to examine slope activity safety ratio on the strength of the natural sample or soil collected through field test in the slope activity region during destruction happened in the course of soil-relocating work planned for ground improvement under strict supervision at the house-building site, using Bishop's slope analysis method and investigate relationship between slope analysis theories and actual destruction so as to compare determining method of clean water of soil essential for slope activity analysis and accuracy of resulting value of clean water of soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.655-662
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• 2005

The objective of this thesis is to develop a prediction system of potential landslide sites to apply to the prevention of landslide disaster which occurred during the heavy rainfall in the rainy season. The system was developed by combining a modified slope stability analysis model and a hydrological model. The modified slope stability analysis model, which was improved from 1-D infinite slope stability analysis model, has been taken into consideration of the flexion of the hill slopes. To evaluate its applicability to the prediction of landslides, the data of actual landslides were plotted on the predicted areas on the GIS map. The matching rate of this model to the actual data was 92.4%. And the relations between wetness index and landform factors and potential landslide were analyzed.

• Journal of Integrative Natural Science
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• v.10 no.4
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• pp.232-239
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• 2017

The researcher set up multiple sensor units on the road slope such as national highway and highway where there is a possibility of loss, and using the acceleration sensor built into the sensor unit the researcher will sense whether the inclination of the road slope occur in real time, and Based on the sensed data, the researcher tries to implement a system that detects collapse of road slope and dangerous situation. In the experiment of measuring the error between the actual measurement time and the judgment time of the monitoring system when judging the warning of the sensor and falling rock detection by using the acceleration sensor, the error between measurement time and the judgment time at the sensor warning was 0.34 seconds on average, and an error between measurement time and judgment time at falling rock detection was 0.21 seconds on average. The error is relatively small, the accuracy is high, and thus the change of the slope can be clearly judged.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.57-62
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• 2009

Flame spread velocity to virgin surface fuel bed on a ground slope increases as the flame gets closer to the slope according to the change of a ground slope angle. The existing studies have generally adopted the theory that flame gets closer to the slope as the slope angle increases, without considering the change of flame tilt against the slope. In this study, experiments were made on the actual characteristics of the flame on slopes of various angles, and as a result, this study offers the flame tilt equation according to the slope angle, and derive correlation between flame tilt and flame spread velocity on slope conditions.