• KEPCO Journal on Electric Power and Energy
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• v.5 no.2
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• pp.83-92
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• 2019

Spontaneous combustion propensity of various coals of carbonization grade as a pulverized fuel of coal-fired power plant has been tested from an initial temperature of $25^{\circ}C$ to $600^{\circ}C$ by heating in an oven with air to analyze the self-oxidation starting temperature. These tests produce CPT (Cross Point Temperature), IT (Ignition temperature), and CPS (Cross Point Slope) calculated as the slope of time taken for a rapid exothermic oxidation reaction at CPT base. CPS shows a carbonization rank dependence whereby wood pellet has the highest propensity to spontaneous combustion of $20.995^{\circ}C/min$. A sub-bituminous KIDECO coal shows a CPS value of $15.370^{\circ}C/min$, whereas pet coke has the highest carbonization rank at $2.950^{\circ}C/min$. The nature of this trend is most likely attributable to a concentration of volatile matter and oxygen functional groups of coal surface that governs the available component for oxidation, as well as surface area of fuel char, and constant pressure molar heat.

• Korean Journal of Remote Sensing
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• v.37 no.5_3
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• pp.1425-1434
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• 2021

Continuous and periodic data acquisition must be preceded to maintain and manage the river facilities effectively. Adapting the existing general facilities methods, which include river surveying methods such as terrestrial laser scanners, total stations, and Global Navigation Satellite System (GNSS), has limitation in terms of its costs, manpower, and times to acquire spatial information since the river facilities are distributed across the wide and long area. On the other hand, the Mobile Mapping System (MMS) has comparative advantage in acquiring the data of river facilities since it constructs three-dimensional spatial information while moving. By using the MMS, 184,646,009 points could be attained for Anyang stream with a length of 4 kilometers only in 20 minutes. Levee points were divided at intervals of 10 meters so that about 378 levee cross sections were generated. In addition, the waterside maximum and average slope could be automatically calculated by separating slope plane form levee point cloud, and the accuracy of RMSE was confirmed by comparing with manually calculated slope. The reference slope was calculated manually by plotting point cloud of levee slope plane and selecting two points that use location information when calculating the slope. Also, as a result of comparing the water side slope with slope standard in basic river plan for Anyang stream, it is confirmed that inspecting the river facilities with the MMS point cloud is highly recommended than the existing river survey.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.78-89
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• 2017

Spontaneous combustion propensity of various coals of carbonization grade as a pulverized fuel of coal fired power plant has been tested from an initial temperature of $25^{\circ}C$ to $600^{\circ}C$ by heated in an oven with air to analyze an self oxidation starting temperature. This tests produce a CPT(Cross Point Temperature), IT(Ignition temperature) and CPS(Cross Point Slope) by calculated as the slope of time taken a rapid exothermic oxidation reaction at CPT base. CPS show a carbonization rank dependence, whereby wood pellet has the highest propensity to spontaneous combustion of $20.995^{\circ}C/min$. A subbituminous KIDECO coal shows an CPS values of $15.370^{\circ}C/min$ whereas it of pet coke of the highest carbonization rank has $20.950^{\circ}C/min$. The nature of this trend is most likely a concentration of volatile matter and oxygen functional groups of coal surface that governs the available component for oxidation as well as surface area of fuel char, and constant pressure molar heat.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.1
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• pp.67-77
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• 2018

The objective of this study is to extract the shape of the slope from the images acquired using UAV and evaluate its suitability and reliability when applied to slope stability analysis. UAV is relatively inexpensive and simple, and it is possible to make terrain survey by generating point clouds. However, the image acquired from UAV can not be directly photographed by the forest canopy due to the influence of trees, resulting in severe distortion of the terrain. In this study, therefore, the effects of forest canopy were verified and the slope stability analysis was performed. Images acquired in winter and summer were used, because summer images are heavily influenced by the forest canopy and winter images are not. As a result of the study, the winter image is suitable for the extraction of slope shape, but severe terrain distortion occurs in the summer image. Therefore, slope stability analysis using slope shape extracted from summer image is impossible, so it should be modified for slope stability analysis. The modified slope did not completely eliminate the distortion of the terrain, but it could express the approximate shape of the slope. As a result of the slope stability analysis, the location and shape of the failure surface are the same, and the error of the safety factor is less than 0.2, which is close to the actual slope.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.15-22
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• 1985

The author has studied the collapse of a slope with seepage occuring in sand model with a trapezodial cross section. The primary objective of this study was to examine the failure phenomenon of embankment with respect to change in void pressure at embankment slope. The contents of this experiments are as follows; 1) Determination of exit point by seepage line. 2) Evaluation of partial failure at exit point. 3) The effects of seepage force at embankment.

• Journal of Biosystems Engineering
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• v.2 no.1
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• pp.33-48
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• 1977

Transporting agricultural products and the other material by the two-wheel-tractor (power-tiler)and trailer system may be one of its most widely used farming functions.The safety and hitching load for all the previaling performing conditions may be the general concern over the operation of the tiller-trailer system. In this study, a mathematical model to determine the static and dynamic forces excerting on the hitch point were developed . Based on the analysis of the model and the field measurements. the limiting hitching load and critical slope were analyzed. The results of the study are summarized as follows ; 1) The limit angle of slope land for the safety steering that two-wheel tractor-single axle trailer system was able to transport agricultural products was the direct angle (${\gamma}$) = 8 ; the cross angle$\beta$) 15 ; and it was decreased in accordance with the increase of carrying load ($W_4). 2) The critical velocity for safe operation in case of running on downward hill road was about 1.08m/sec. 3) The limiting carrying load for the safe steering was W$_4$=600kg. The degree of the safe steering for different braking methods was given in order as follows ; Simulataneous braking the tractor and trailer , braking the trailer only, and braking tractor only. 4) Among the three components of impact loads excerting on the hitch point, the component in the lateral direction ($P_{Vy}$) was near zero in spite of increase of hitching load ($W_4) , while the components in the other two mutually perpedicular directions ($P_{Vx}$ and ($P_{Vz}$) ) had larger values in horizontal plane than those in the slope lands. 5) Moment of forces on the lateral direction (M$y$) had the largest value among the three components of impact moment acting on the hitch point, however all the components were sharply increased in accordance with the increase of hitching loads ($W_4. Three components of the moment were the negative values.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.4
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• pp.311-319
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• 2013

As heavy rains occur more frequently due to the recent climate change, slope collapses are increasing, and damage to human life and properties is accordingly increasing every year. The most proper method to take preventive measures against slope collapses is to remove the cause after understanding the cause of slope collapse in advance, and for such, slope safety inspection is implemented for preventive purposes, to investigate the cause, and as a measure for restoration. Thus, this Research was able to reach the following conclusion after utilizing LiDAR, which obtains detailed topographic information in a short period of time with point cloud data on slopes subject to safety inspection. First, as a result of analyzing the errors after installing a check point in the subject area, the RMSE of the horizontal location error appeared to be ${\pm}2.2cm$ and the RMSE of the vertical location error appeared to be ${\pm}3.0cm$, which shows a practically satisfactory result. Second, the economic feasibility was outstanding and obtaining accurate topographic information was available. Third, an area once scanned allowed to accurately obtain an unprescribed cross-sectional diagram in a short period of time, thus, appeared to be convenient for experts to detect dangerous sections.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.7-11
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• 2001

In this paper, trapezoid sections and prominence sections were examined to improve the performance of floating breakwater in long waves. The linear potential theory is used and the boundary element method with a matching boundary is employed for numerical computation. The effects of the side slope of the trapezoid section and the geometry ratio of the prominence section on the floating breakwater were examined. It was found that trapezoid sections show lower transmission coefficients than the rectangular sections in the long wave range. In prominence sections the size of the sides are more important than the size of the top. Proper choices of the pontoon type geometry may move the local minimum point of the wave transmission coefficient toward the longer wave ranges and improve the performance of the floating breakwater in the long wave range for a given wave period.

• Journal of Korea Water Resources Association
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• v.44 no.3
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• pp.179-188
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• 2011

In this study, the regional factors in Gangwondo were used to analysis the relationship between point precipitation and areal precipitation. The most province area in Gangwondo is consist of mountainous terrain. At the east part of the Taebaek Mountains, the slope is very steep and the coastal plains don't exist. At the west part of the Taebaek Mountains, the slope is mild, there are many rivers, such as South Han-river and North Han-river, and the regions are very complex terrain. The data of 66 stations in Gangwondo and the PRISM (Parameter-elevation Regression on Indepedent Slope Model) were used to estimate the spatial distribution of precipitation. According to the topographic conditions, such as elevation and slope, and the regional conditions, such as Youngdong and Youngseo, the spatial distribution of precipitation is well shown. At the results of cross-validation, the RRBIAS and the RRMSE are under 0.1 and therefore the analysis of the PRISM are well conducted. Consequently the PRISM in this study is a appropriate method to estimate the spatial distribution of precipitation in Gangwondo.

• Smart Structures and Systems
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• v.22 no.3
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• pp.291-302
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• 2018

This paper presents a flexibility based method for damage identification from static measurements in beam-type structures. The response of the beam at the Damaged State is decomposed into the response at the Reference State plus the response at an Incremental State, which represents the effect of damage. The damage is localized by detecting slope discontinuities in the deflection of the structure at the Incremental State. A denoising filtering technique is applied to reduce the effect of experimental noise. The extent of the damage is estimated through comparing the experimental flexural stiffness of the damaged cross-sections with the corresponding values provided by analytical models of cracked beams. The paper illustrates the method by showing a numerical example with two cracks and an experimental case study of a simply supported steel beam with one artificially introduced notch type crack at three damage levels. A Digital Image Correlation system was used to accurately measure the deflections of the beam at a dense measurement grid under a set of point loads. The results indicate that the method can successfully detect and quantify a small damage from the experimental data.