• Geomechanics and Engineering
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• v.30 no.2
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• pp.123-138
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• 2022

Present study computes the ultimate bearing capacity of an embedded strip footing situated on the rock slope subjected to seismic loading. Influences of embedment depth of strip footing, horizontal seismic acceleration coefficient, rock slope angle, Geological Strength Index, normalized uniaxial compressive strength of rock mass, disturbance factor, and Hoek-Brown material constant are studied in detail. To perform the analysis, the lower bound finite element limit analysis method in combination with the semidefinite programming is utilized. From the results of the present study, it can be found that the magnitude of the bearing capacity factor reduces quite substantially with an increment in the seismic loading. In addition, with the increment in slope angle, further reduction in the value of the bearing capacity factor is observed. On the other hand, with an increment in the embedment depth, an increment in the value of the bearing capacity factor is found. Stress contours are presented to describe the combined failure mechanism of the footing-rock slope system in the presence of static as well as seismic loadings for the different embedment depths.

• Geomechanics and Engineering
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• v.33 no.5
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• pp.507-518
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• 2023

The effects of various supporting arrangements have been investigated on an excavation support system using a numerical tool. The purpose of providing different supporting arrangements was to limit the pile wall deflection in the range of 0.5% to 1% of the excavation depth. Firstly, a deep excavation supported by sheet pile wall was modeled and the effects of sheet pile wall thickness, excavation depth and distance to adjacent footings from sheet pile wall face were explored on the soil deformation and wall deflection. Further analysis was performed considering six different arrangements of tieback anchors and struts in order to limit the wall deflections. Case-01 represents the basic excavation geometry supported by sheet pile wall only. In Case-02, sheet pile wall was supported by struts. Case-03 is a sheet pile wall supported by tieback anchors. Likewise, for the Cases 04, 05 and 06, different arrangements of struts and tieback anchors were used. Finally, the effects of different supporting arrangements on soil deformation, sheet pile wall deflection, bending moments and anchor forces have been presented.

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.41-48
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• 2013

This paper is intended to provide the background information and justification for Korean highway bridge design code(limit state design)(2012). Limit state design method calculates reliability index and probability of failure through the analysis of the reliability of the experimental database. It has become possible to perform the economical and consistent design by evaluating the safety of a structure quantitatively. In this paper, we used the design specifications of RC slab bridge of superstructure form of Road Design Manual in Part 5 bridge built in highway bridge. This study conducted structural analysis using the method of frame structure theory, design and analysis of bridge by limit state design method, the design code including various standards and Load model applied Korean highway bridge design code limit state design(KHBDC;2012). As a result, it analyzed the effect of safety through comparison. Showing effect of improvement the safety factor and comparing the value of the result, it is determined to be capable of economical design and safety. Furthermore, limit state design method was able to determine many redundant force of cross-section compared with existing design method. It is determined that it can reduce the overall amount because of the reduction of the cross-section and girder depth.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.3
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• pp.59-67
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• 1984

This study was carried out to find physical and mechanical properties of soil in Yongsan project area to support basic data for tidalland reclamation. The main results are as follows. 1. Most of the soils in this area consist of clay and silt, and inorganic materials. 2. Natural moisture contents are ranged from 42.2% to 92.9% initial void ratio, from 1.4 to 2.3 Therefore it takes a longtime in Settlement of considerable depth. 3. Wet unit weights decrease with increasing of the nataral moistare contents as rt=2. 005-0. 0065wn.4. The relationships between compression index. and liquid limit, initial void ratio and natural moisture contents are found as follows respectively. Cc =0. 046+0. O12LL Cc=-0. 068+0.367eo Cc =0. 056+0. OO8Wn 5. Natural moisture content, plastic limit, plastic index, initial void ratio and liquid :limit are directly proportional to clay content ratio. The relationships are found as Wn=26. 083+0. 797Cy PL=14. 223+0. 128Cy P1=0. 457+0. 492Cy eo=0. 757+0. O2Ocy LL=14. 695+0. 620Cy. 6. Initial void ratio and liquid limit are directly proportional to natural moisture con-tent as follows. eo=0. 310+0.022wn LL=6. 275+0.592wn

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.453-458
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• 2001

Pipelines have the highest capacity and are the safest and the least environmentally disruptive way for gas or oil transmission. Recently, failures due to corrosion defects have become of major concern in maintaining pipeline integrity. A number of solutions have been developed for the assessment of remaining strength of corroded pipelines. However, these solutions are known to be dependent on material properties and pipeline geometries. In this paper, a Fitness-For-Purpose type limit load solution for corroded gas pipelines made of the X65 steel is proposed. For this purpose, a series of burst tests with various types of corrosion defects are performed. Finite element simulations are carried out to derive an appropriate failure criterion. And then, further, extensive finite element analyses are performed to obtain the FFP type limit load solution for corroded X65 gas pipelines as a function of defect depth, length and pipeline geometry. And also, a window based computer program far the assessment of corrosion defect, which is named as COPAP(COrroded Pipeline Assessment Program) has been developed on the basis of proposed limit load solution.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.1079-1089
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• 2017

Nuclear power plants under expansion and under construction in China are mostly located in coastal areas, which means they are at risk of suffering strong earthquakes and subsequent tsunamis. This paper presents a safety analysis for a new reinforced concrete containment vessel in such events. A finite element method-based model was built, verified, and first used to understand the seismic performance of the containment vessel under earthquakes with increased intensities. Then, the model was used to assess the safety performance of the containment vessel subject to an earthquake with peak ground acceleration (PGA) of 0.56g and subsequent tsunamis with increased inundation depths, similar to the 2011 Great East earthquake and tsunami in Japan. Results indicated that the containment vessel reached Limit State I (concrete cracking) and Limit State II (concrete crushing) when the PGAs were in a range of 0.8-1.1g and 1.2-1.7g, respectively. The containment vessel reached Limit State I with a tsunami inundation depth of 10 m after suffering an earthquake with a PGA of 0.56g. A site-specific hazard assessment was conducted to consider the likelihood of tsunami sources.

• The Journal of Korea Robotics Society
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• v.15 no.4
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• pp.341-349
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• 2020

Recently, interest in ground subsidence in urban areas has increased after a large sinkhole occurred near the high-story building area in Jamsil, Seoul, Korea, in 2014. If a massive sinkhole occurs in an urban area, it is crucial to assess its risk rapidly. Access to humans for on-site safety diagnosis may be difficult because of the additional risk of collapse in the disaster area. Generally, inspection using drones equipped with high-speed lidar sensors can be utilized. However, if the sinkhole is created vertically to a depth of 100 m, similar to the sinkhole in Guatemala, the drone cannot be applied because of the wireless communication limit and turbulence inside the sinkhole. In this study, a three-dimensional (3D) scanning system was fabricated and operated using a towed cable in a massive vertical sinkhole to a depth of 200 m. A high-speed lidar sensor was used to obtain a continuous cross-sectional shape at a certain depth. An inertial-measuring unit was applied to compensate for the error owing to the rotation and pendulum movement of the measuring unit. A reconstruction algorithm, including the compensation scheme, was developed. In a vertical hole with a depth of 180 m in the mining area, the fabricated system was applied to scan 0-165 m depth. The reconstructed shape was depicted in a 3D graph.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.4
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• pp.90-95
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• 1989

The purpose of this study is to seek out the harrow water requirement applicable for the irrigation plan of paddy field and to find out the factors influenced on a variation in the requirement. The plots of experiment were arranged with randomized block design which was compo- sed of three kinds of soil texture (sandy loam, loam and silty loam) and ploughing depth (12cm, 17cm, and 22cm). The results obtained from this experimental study are summarized as follows. 1. Harrow water reguirement is not only changed by soil texture, but influenced by soil water content just before irrigating 2. Magnitude of total harrow water reguirement appli(able for the irrigation plan, when surface water depth and the water content just before irrigating is fixed on the basis of 30 mm and a shrinkage limit respectively, generally becomes to be 177.5mm, 116.3mm and 113. 8mm in the sandy loam, loam amd silty loam block, respectively. 3. The more a percolation of soil layer occurs, the more the harrow water requirement increases, but it is not much influenced by the increase in ploughing depth. 4. The larger a porosity of soil layer is, the more a net harrow requirement increases 5. The factors that influence on a variation in the harrow water requirement are appea- red to be percolation of soil layer, soil water content just before irrigating, porosity of soil layer, ploughing depth and designed surface water depth etc.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.571-576
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• 2023

In this study, the harmless crack size(a_hml) according to the residual stress depth was evaluated using the fatigue limit of SCM440 steel by quenching-tempering(QT) and induction hardening(IH), and threshold stress intensity factor of QT steel. Because the residual stress increased rapidly as the crack depth increased, a_hml was determined at the depth of all the crack aspect ratio(As) regardless of Type I-III, and a_hml also increased according to the residual stress depth. a_hml was minimal at As=1.0 and maximal at As=0.1, but was almost similar on each Type. a_hml was small the dependence on As.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.101-107
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• 1997

In general, grinding is one of the final machining processes which determines the surface quality of machined products. Since the ground surface is affected by the states of grains and voids on the grinding wheel surface, the wheel should be dressed before the machined surface deteriorates over a quality limit This paper describes a systematic approach to decide a proper dressing chance and an optimal dressing depth for the working grinding wheel. An eddy current sensor and a laser displacement sensor are used to measure the loading on the working wheel surface and the topography of the dressed wheel surface respec- tively. The dressing chance can be properly decided through the relational locus between the amount of handing and the machined surface roughness. An optimal dressing depth to guarantee the less wheel loss and the higher wheel surface quality is decided through the analysis of the variance of topography for the dressed wheel surface, which decreases at three different rates according to the accumulated dressing depth.