• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.67-76
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• 2007

Raining method has been widely used for preparing sand specimen because of its ability to reconstitute the homogeneous specimen with desired relative density and its reliability established by the numerous experiments on diverse influential factors. In conventional raining methods, adjustment of relative density is achieved by controlling the shutter porosity and the whole system is required to be re-adjusted to achieve the target relative density when the granular characteristics are changed. It is also observed from conventional methods that certain degrees of spatial variation in density exist and the limited range of relative density is reproduced. In this paper, raining system with porous plate is proposed. It is shown that the wide range of relative density can be achieved by controlling failing height only. This enhanced system is able to obviate the subtle control of shutter porosity and minimize the effect of falling distance, which in turn ensures the homogeneity of the specimen, especially for low relative density.

• Geomechanics and Engineering
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• v.14 no.2
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• pp.131-139
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• 2018

The preparation of repeatable and uniformly reconstituted soil specimens up to the specified conditions is an essential requirement for the laboratory tests. In this study for large samples replication, the simultaneous usage of the traveling pluviation and curtain raining technique is used to develop a new method, called the curtain travelling pluviator (CTP). This simple and cost effective system is based on the air pluviation approach, whilst reducing the sample production time, can reproduce uniform samples with relative densities ranging from 25% to 96%. In order to investigate the resulting suitability and uniformity from the proposed method, a series of tests is performed. The effect of curtain traveling velocity, curtain width, drop height, and flow rate on the parameters of the sample is thoroughly investigated. Increase in the curtain velocity and drop height leads to the increase in relative density for the sand specimen. Increase in curtain width typically resulted in the reduction of relative density. Test results reveal that the terminal drop height for the sand specimen in this study is more than 500 mm. Relative density contour lines are presented that can be utilized in optimizing the drop height and curtain width parameters. Sample uniformity in the vertical and horizontal orientation is investigated through the sampling containers. Increasing relative density tends to result in the higher sample repeatability and uniformity.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.29-42
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• 1999

The SASW (Spectral-Analysis-of-Surface-Waves) method, which evaluates the stiffness structure of the subsurface and structures nonintrusively and nondestructively, has been successfully used in the civil engineering applications. However, the SASW method assumes that the subsurface or structures consist of horizontal multi-layers, so that the method has some difficulty in continuously evaluating the integrity of a tunnel lining and a pavement system. This difficulty prevents the SASW method from being used to generate a tomographic image of stiffness for the subsurface or structures. Recently, the GPR technique which has the advantage of continuously evaluating integrity of the subsurface and structures has been popular. This advantage of GPR technique initiated the efforts to make the SASW method, which is superior to GPR and other nondestructive testing methods due to its capability of evaluating stiffness and modulus, be able to do continuous evaluation of stiffness structure, and the efforts finally lead to the development of \ulcornerTomographic SASW Technique.\ulcorner Tomographic SASW technique is a variation of the SASW method, and can generate a tomographic image of stiffness structure along the measurement line. The tomographic SASW technique was applied to the investigation of lateral variability of a sand box placed by the raining method for the purpose of verifying its effectiveness. Tomographic SASW measurements on the sand box revealed that the investigated sand box has different shear stiffness along the measurement line, which gave a clue of how to make a better raining device.

• Journal of the Korean GEO-environmental Society
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• v.8 no.5
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• pp.57-65
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• 2007

Slope collapse occurs mostly at the rainy season or thawing season in Korea. From a engineer point of view, the design criterion in recent of soil slopes during the rainfall have a conservative tendency because a slope stability is evaluated in the condition that ground water level is located in the surface. However, for the rational design of soil slopes during rainfall, the raining conditions and the unsaturated soil characteristics of soil slopes have to be considered. For the unsaturated soil characteristics of soil slopes, the laboratory tests for unsaturated soils and the seepage analyses for the raining conditions have to be performed. Due to these difficulties, a conservative design of soil slopes in the current design criterion has been carried out. In this paper, therefore, a simple design method is proposed. The method is considered to the unsaturated soil characteristics and the results of seepage analysis without numerical analysis. To verify the suggested design method, it is compared with both analysis results by current design criterion and analysis results based on the seepage analysis. Through the comparative study, it was found that the current design criterion has been excessively conservative. Hence, simple design method in this study was evaluated as the rational design for the soil slopes during rainfall.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.6
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• pp.345-351
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• 2014

This paper presents pedestrian recognition to improve performance for vehicle safety system or surveillance system. Pedestrian detection method using HOG (Histograms of Oriented Gradients) has showed 90% recognition rate. But if someone takes a picture in the rain, the image may be distorted by rain streaks and recognition rate goes down by 62%. To solve this problem, we applied image decomposition method using MCA (Morphological Component Analysis). In this case, rain removal method improves recognition rate from 62% to 70%. However, it is difficult to apply conventional image decomposition method using MCA on vehicle safety system or surveillance system as conventional method is too slow for real-time system. To alleviate this issue, we propose a rain removal method by using low-pass filter and DCT (Discrete Cosine Transform). The DCT helps separate the image into rain components. The image is removed rain components by Butterworth filtering. Experimental results show that our method achieved 90% of recognition rate. In addition, the proposed method had accelerated processing time to 17.8ms which is acceptable for real-time system.

• Journal of Environmental Science International
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• v.16 no.9
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• pp.1099-1102
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• 2007

This paper presents eco-friendly planting method to overcome the problems of existing concrete retaining wall and gabion retaining wall, respectively, based on the examination on existing concrete and gabion retaining wall. Prior to doing this, proper design method was provided through pull out test. Planting method using gabion metal net and L shape green net retaining wall were compared and analyzed. According to this study, it is confirmed that reduction of construction period and economical profit in construction can be achieved by both manufacturing at the factory and self procurement at the job site as well as the use of metal net, which is applied as a substitution of existing strengthening material. For the effect of planting method, the use of L shape green net retaining wall shows superiority to environment-friendly gabion retaining wall in its ability to rootage and germination of the grass. The L shape green net retaining wall had excellent performance in helping rootage of grass and prevention of soil leakage, and even if raining period, remarkable damage of planting mat does not occur when planting mat is applied.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.191-193
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• 2007

Pantograph sliding plate abrasion auto-detect system, one of the electric rail car auto-detecting devices, is a system that decides how much abrasion and when to replace without an inspector physically looking at the abrasion on the wet plate using machine vision, a cutting-edge technology. This paper covers the cause of deteriorating reliability that affects pantograph wet plate edge detection due to noise added to the video when it rains. In order to remove such noise, problems should be checked through Smoothing, Averaging mask and Median filter using filtering technique and stable edge detection without being affected by noise should be induced in video measurement used in machine vision technology.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.139-146
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• 1997

In this study, centrifugal model tests were performed to investigate the behavior of excavated earth retaining wall with the depth of excavation and different types of wall(aluminum, steel panel). Jumunjin standard sand was used for foundation soil. The raining method was adopted to form the required relative density of the model ground. The lateral earth pressure measured from tests were compared with estimated active earth pressure by Rankine's theory. The test results have shown that the earth pressure acting on the retaining wall and the rotation displacement of the wall are influenced by the depth of excavation and the type of wall. It was found from the test results that the deformation of the wall increases with the depth of excavation.

• International Journal of Internet, Broadcasting and Communication
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• v.6 no.2
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• pp.20-24
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• 2014

These days the large-scale car accidents have often been occurred by overspeeding in disregard of sharp curve, foggy and freezing regions. This paper has proposed the algorithm to calculate the safety speed in real time that can protect the car accidents under these weather and road conditions using Fuzzy reasoning theory. Under raining and snowing, drivers have to slow down the traffic safety speed by 1/3 of the traffic safety speed indicated on the existing speed sign plate based on their decision. So it is difficult to calculate and then observe the safety speed. This paper has performed the simulation that provides the deivers with the optimal safety speed considering the road and weather conditions in real time to improve these problems. We have proved this method can improve more 25% than the existing one.

• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.98-106
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• 2006

The substructure of temporary bridges used during the construction period of main bridges needs to be simple and strong at the same time so that it doesn't block running water. When the water flow is hindered by sub-structure of the bridges, as it happens when H beams with bracing are used, either the water floods or the bridge gets damaged. Therefore, using round beams for the substructure and connect them together is a preventive choice considering the intensive raining in the summer. The bridges using round beams for the substructure have also benefited by fast construction because of fewer bracing and in-situ welding. Because the round-pile-connecting method is relatively new, the safety evaluation of the constructed bridge is an essential procedure before being used in the field. The field evaluation of a bridge including the vehicle loading test and moving load analysis has been conducted and the results showed the safety requirement is satisfied.