• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.5
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• pp.140-154
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• 1996

In this study, displacement, deformation, and stability according to change of cohesion and internal friction angle were investigated through elasto-plastic method, finite-element method, and in-site experiment when excavating soft ground using sheet pile. The results of the study were as follows : 1. The horizontal displacement was 5.5% of the excavation depth by the elasto-plastic method and 3.9% of the excavation depth by the on-site experiment at the final excavation depth(GL-8.Om) on the condition of double stair strut after excavating GL-6.Om. 2. Relationships between cohesion(c) and internal friction angle $({\varphi})$ when safety factor to the penetration depth was 1.2 is shown in the following equations : (a) c= -O.0086$({\varphi})$+ O.3(D=3m) and (b) c=-0.00933$({\varphi})$+0.14(D=4m). 3. The results of elasto-plastic method and the experiment show that possible excavation depth was GL-6.Om after setting single stair strut in a short period in terms of possibility of carrying out on the condition of experimental site on the contrary general reinforcement method, setting double stair strut after excavating GL-4.0m. 4. After setting the strut, distribution of the horizontal displacement had concentrated on the excavation base and possible local failure which the shear strain caused decreased by the strut reinforced. 5. After setting strut, displacement of sheet pile was decreased by half, the limit of stable excavation depth of ground was GL-8.Om, and the maximum horizontal displacement at the GL-8.Om was 1.6% of excavation depth by the elasto-plastic method, 0.7% of excavation depth by the finite-element method.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.273-287
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• 2006

This study investigates the failure mechanism and load-carrying capacity of a single-shell lining which has no disturbance in transfer of shear force, with respect to a conventional double-shell lining which has separation between layers of shotcrete lining and secondary concrete lining by water-proof membrane. In order to evaluate the capacity, a 2-D numerical investigation is preliminarily carried out and then real-scale loading tests with tunnel lining section specimens are performed on the condition given by the numerical investigation. In the test, a concentrated load is applied for considering a released ground load or rock wedge load. Through this study, it appears that the single-shell lining takes the load-bearing capacity 20% higher than in case of the double-shell lining. In addition, a possibility of a composite single-shell shotcrete layer composed by multiple bonded layers partly involving different contents of high-capacity additives is shown thereby leading to use of less amount of the high-capacity additives on the condition of taking a similar load-bearing capacity.

• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.117-126
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• 2005

The chemical property analysis on the deposited clay using scanning electron microscope and energy dispersive x-ray spectrometer were performed. Also, the triaxial compression tests and consolidation tests using NaCl aqueous solution and leachate as substitute pore (or saturated) water in samples were carried out to find out the behaviour characteristics of strength and deformation of contaminated deposited clay. from the chemical composition analysis results of clay samples, the magnitudes of composition ratio were revealed in the order of O, C, Si, Al, and Fe. Of these, why the ratio of carbon appeared to be large is estimated as due to the increase of the phyto-planktons after the construction of tide embankment. In the triaxial compression test and consolidation test results, the shear strength and compression properties have increased with the increase in concentration of contaminant (NaCl). This phenomenon is considered as to be caused by the changes of soil structure to flocculent structure owing to the decrease in the thickness of diffuse double layer in proportion to increase in the concentration of electrolyte.

• Steel and Composite Structures
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• v.36 no.5
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• pp.507-519
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• 2020

Double skin composite walls are increasingly popular and have been applied to many safety-related facilities. They come from the concept of composite slabs. Conventional connectors such as shear studs and binding bars were used in previous studies to act as the internal mechanical connectors to lock the external steel faceplates to the concrete core. However, the restraint effects of these connectors were sometimes not strong enough. In this research, a recently proposed unique type of steel truss was employed along the wall height to enhance the composite action between the two materials. Concrete-filled tube columns were used as the boundary elements. Due to the existence of boundary columns, the restraints of steel faceplates to the concrete differ significantly for the walls with different widths. Therefore, there is a need to explore the effect of height-to-width ratio on the structural behavior of the wall. In the test program, three specimens were designed with the height of 3000 mm, the thickness of 150 mm, and different widths, to simulate the real walls in practice. Axial compression was applied by two actuators on the tested walls. The axial behavior of the walls was evaluated based on the analysis of test results. The influences of height-to-width ratio on structural performance were evaluated. Finally, discussion was made on code-based design.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.549-556
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• 2009

This research analyzed the structural efficiency and application by improving the 100 mm width vertical joint to 150 mm and developing three connection methods to reduce the difficulty in assembling and handling PC walls. Moreover, nonlinear finite analysis was used for analyzing. From the analysis results, when double width connection was applied, the PC wall showed larger load capacity and ductility due to the steel bar sharing loads efficiently. Moreover, as the dimension of loops and the number of bars increased, the maximum load capacity increased as well. Also, among the double width connections, the largest capacity showed in the order of welding, ring and C type loop. However, in case of welding type loop connection, the ring type loop is more stable due to changes in different site conditions. Therefore, thorough quality control of welding is necessary.

• Steel and Composite Structures
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• v.34 no.2
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• pp.261-277
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• 2020

The main objective of this research paper is to consider vibration analysis of vacancy defected graphene sheet as a nonisotropic structure via molecular dynamic and continuum approaches. The influence of structural defects on the vibration of graphene sheets is considered by applying the mechanical properties of defected graphene sheets. Molecular dynamic simulations have been performed to estimate the mechanical properties of graphene as a nonisotropic structure with single- and double- vacancy defects using open source well-known software i.e., large-scale atomic/molecular massively parallel simulator (LAMMPS). The interactions between the carbon atoms are modelled using Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential. An isogeometric analysis (IGA) based upon non-uniform rational B-spline (NURBS) is employed for approximation of single-layered graphene sheets deflection field and the governing equations are derived using nonlocal elasticity theory. The dependence of small-scale effects, chirality and different defect types on vibrational characteristic of graphene sheets is investigated in this comprehensive research work. In addition, numerical results are validated and compared with those achieved using other analysis, where an excellent agreement is found. The interesting results indicate that increasing the number of missing atoms can lead to decrease the natural frequencies of graphene sheets. It is seen that the degree of the detrimental effects differ with defect type. The Young's and shear modulus of the graphene with SV defects are much smaller than graphene with DV defects. It is also observed that Single Vacancy (SV) clusters cause more reduction in the natural frequencies of SLGS than Double Vacancy (DV) clusters. The effectiveness and the accuracy of the present IGA approach have been demonstrated and it is shown that the IGA is efficient, robust and accurate in terms of nanoplate problems.

• Food Science of Animal Resources
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• v.39 no.1
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• pp.45-53
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• 2019

This study observed the effects of the double combination of temperatures-times (2 temperatures: 2 times combination, 2T2T) in sous vide cooking method on the physicochemical properties and collagen solubility (CS) of semitendinosus muscle from cattle and goat as a comparison to common sous vide treatment (1 temperature: 1 time combination, 1T1T). The new invention of sous vide cooking method (2T2T) cooked at the first temperature at $45^{\circ}C$ for 3 h, and the second temperature at $60^{\circ}C$, $65^{\circ}C$, and $70^{\circ}C$ for 3 h, and labeled as N45-60, N45-65, and N45-70, respectively. While, common sous vide treatment (1T1T) were cooked directly for 6 h at $60^{\circ}C$ (T60), $65^{\circ}C$ (T65), and $70^{\circ}C$ (T70). Results revealed that cooking with 2T2T treatment improved the water-holding capacity and reduced the cooking loss of both beef and goat meat. The $L^*$ values have no apparent changes between treatment in beef and goat meat, while $a^*$ values of N45-60 treated goat presented markedly higher values than other treatments but an only slight increase in beef at the same treatment (p>0.05). Again, 2T2T treatment tended to decrease mean shear force (SF) values for beef and goat meat with the lowest SF values recorded at N45-60, and the CS no or less influenced this value. Therefore, the application of innovative sous vides cooking method (2T2T) presented comparable values in the treated beef and goat meat as compared to common sous vide method (1T1T).

• Composites Research
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• v.31 no.6
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• pp.304-310
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• 2018

Autoclave process has been remaining as one of the most robust and stable process in fabricating structural composite part of aerospace industry. It has lots of advantages, however exhibits some disadvantages or limitations in capital investment and operation. Recently, there have been various Out-of-Autoclave process being researched and developed to overcome those limitations. In this study, laminate specimens were fabricated using LCM (Liquid Composite Molding) process, regarded as one of potential OoA process. DB (Double bagging), CAPRI (Controlled Atmospheric Pressure Resin Infusion), VAP (Vacuum Assisted Process) and Autoclave process were used for laminate specimens. Void content, Thickness, Tg (Glass Transition Temperature), ILSS (Interlaminar Shear Strength) and Flexural strength properties were evaluated for comparison. It is verified that Autoclave based specimen has uniform thickness distribution, the lowest void content and outstanding mechanical properties. And, CAPRI based specimen exhibits relatively good physical and mechanical properties over DB and VAP based specimen and comparable mechanical properties with autoclave based specimen.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6C
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• pp.241-253
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• 2010

For seismic design of a vertical shaft, three-dimensional Finite Element (FE) analyses were performed to evaluate the accurate response of a vertical shaft and to apply a Response Displacement Method (RDM). Special attention is given to the evaluation of seismic base and response displacement of surrounding soil, estimation of load and loading method. Based on the result, it was found that shear wave velocity of seismic base greater than 1500m/s was appropriate for the seismic design. It was also found that double cosine method which evaluates a response displacement of surrounding soil was most appropriate to consider the characteristic of multi-layered soil. Finally, shape effect of the structure was considered to clarify the dynamic behavior of vertical shaft and it would be more economical vertical shaft design when a vertical shaft was analyzed by using RDM.

• Journal of the Korean Geophysical Society
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• v.5 no.4
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• pp.321-328
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• 2002

Difficulties encountered in downhole S-wave (shear wave) surveys include the precise determination of shear wave travel times and determination of geophone orientation relative to the direction of polarization caused by the seismic source. In this study an S-wave enhancing and a principal component analysis method were adopted as a tool for determination of S-wave arrivals and the direction of polarization from downhole S-wave survey data. An S-wave enhancing method can almost double the amplitudes of S-waves, and the angle between direction of polarization and a geophone axis can be obtained by a principal component analysis. Once the angle is obtained data recorded by two horizontal geophones are transformed to principal axes, yielding so called scores. The scores gathered along depth are all in-phase, consequently, the accuracy of S-wave arrival picking could be remarkably improved. Applying this processing method to the field data reveals that the test site consists of a layered ground earth structure.