• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.634-639
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• 2009

The response displacement method is the most frequently used method for the seismic design of underground structures. Underground structures under seismic loading will tend to deform with the surrounding ground, and thus the structure is designed to accommodate the free-field deformation without loss of its structural integrity. This method is pseudo-static method, and response displacement of surrounding ground are most important steps. In this study, the single cosine method and the equivalent linear analysis are applied to estimate the response displacement of the real sites, and the results of the each method are compared. Response analysis was also performed with respect to bedrock depth. As a results, Equivalent linear analysis result was larger than single cosine method. And, the relative displacement becomes lager according to depth of the bedrock.

• Computers and Concrete
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• v.20 no.2
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• pp.129-143
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• 2017

Seismic design of reinforced concrete (RC) structures requires a certain minimum level of flexural ductility. For example, Eurocode EN1998-1 directly specifies a minimum flexural ductility for RC beams, while Chinese code GB50011 limits the equivalent rectangular stress block depth ratio at peak resisting moment to achieve a certain nominal minimum flexural ductility indirectly. Although confinement is effective in improving the ductility of RC beams, most design codes do not provide any guidelines due to the lack of a suitable theory. In this study, the confinement for desirable flexural ductility performance of both normal- and high-strength concrete beams is evaluated based on a rigorous full-range moment-curvature analysis. An effective strategy is proposed for flexural ductility design of RC beams taking into account confinement. The key parameters considered include the maximum difference of tension and compression reinforcement ratios, and maximum neutral axis depth ratio at peak resisting moment. Empirical formulae and tables are then developed to provide guidelines accordingly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1270-1279
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• 2002

Residual stress is a dominant obstacle to efficient production and safe usage of device by deteriorating the mechanical strength and failure properties. Therefore, we proposed a new thin film stress-analyzing technique using a nanoindentation method. For this aim, the shape change in the indentation load-depth curve during the stress-relief in film was theoretically modeled. The change in indentation depth by load-controlled stress relaxation process was related to the increase or decrease in the applied load using the elastic flat punch theory. Finally, the residual stress in thin film was calculated from the changed applied load based on the equivalent stress interaction model. The evaluated stresses for diamond-like carbon films from this nanoindentation analysis were consistent with the results from the conventional curvature method.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.63-71
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• 1999

In evaluating the ultimate strength of a section for a reinforced concrete flexural member, the effect of member length is not usually considered, even though the strength tends to decrease with increase of member length. In this paper the influence of specimen length on flexural compressive strength of concrete was evaluated. For this purpose, a series of C-shaped specimens subjected to axial compression and bending moment were tested using four different length-to-depth ratios (from 1,2,3 and 4) of specimens with compressive strength of 590 kgf/$\textrm{cm}^2$. Results indicate that for the region of h/c <3.0 the reduction in flexural compressive strength with increase of length-to-depth ratios was apparent. A model equation was depth of an equivalent rectangular stress block was larger than that by ACI. It was also founded that the effect of specimen length on ultimate strain was negligible. Finally more general model equation is also suggested.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.4
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• pp.61-66
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• 1996

The subsequent recrystallizations technique, and experimental strain measurement method by use of recrystallization phenomena, has been successfully applied for the observation of machined surface plastic zones with equivalent plastic strain .epsilon. .geq. 0.5, 0.12 and 0.02 of type 304 stainless steel. The depth of the zone with .epsilon. .geq. 0.5 is very small, 10-15 .mu. m, while those with .epsilon. .geq. 0.12 are 100-200 .mu. m and 200-450 .mu. m, respectively. The depths increase with increasing depth of cut and with decreasing rake angle. The relation between the depth of the zones and the cutting paramenters is shown. The deformation state ahead of the quick-stop cut was also well visualized by the technique.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.15-23
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• 2021

In this paper, service life for RC(Reinforced Concrete) substructure subjective to carbonation was evaluated through deterministic and probabilistic method considering field investigation data and Design Code(KDS 14 20 40). Furthermore changes in service life with increasing COV(Coefficient of Variation) and equivalent safety index meeting the same service life were studied. From the investigation, the mean and its COV of cover depth were evaluated to 70.0 ~ 90.0 mm and 0.2, respectively. With intended failure probability of 10.0 % and 70 mm of cover depth, service life decreased to 137 years, 123 years, and 91 years with increasing COV of 0.05, 0.1, and 0.2, respectively. In the case of 80 mm of cover depth, it changes to 179 years, 161 years, and 120 years with increasing COV. The equivalent safety index meeting the same service life from deterministic method showed 1.66 ~ 3.43 for 70 mm of cover depth and 1.61 ~ 3.24 for 80 mm of cover depth, respectively. The various design parameters covering local environment and quality condition in deterministic method yields a considerable difference of service life, so that determination of design parameters are required for exposure conditions and parameter variation.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.1
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• pp.45-55
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• 1998

In this paper, a robust path tracker and depth controller of Autonomous Underwater Vehicle based on sliding mode control is presented. We have also designed augmented equivalent control inputs by analyzing the sliding mode with the reaching mode. This can enhance the reaching rate, and improve chattering problems, that is, noise caused by the control plane actuator of the vehicle, which is one of the problems that occur when sliding mode control is used. Also to resolve the steady state error generated in the path tracker under current effect, a modified sliding plane is constructed. Also a redesigned sliding plane and control input using transformation matrix is proposed to do easy design of MIMO depth controller. For state variables that cannot be measured directly, reduced order sliding mode control is used to design an observer. The performance of designed path tracker and depth controller is investigated by computer simulation. The results show that the proposed control system has robust performance to parameter variation, modelling error and disturbance.

• Computers and Concrete
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• v.24 no.4
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• pp.303-311
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• 2019

The depth of superstructure is the summation of the height of girders and the thickness of the deck floor. In this study, it is aim to determine the maximum span length of girders and minimum depth of the superstructure of prestressed concrete I-girder bridge. For this purpose the superstructure of the bridge with the width of 10m and the thickness of the deck floor of 0.175m, which the girders length was changed by two meter increments between 15m and 35m, was taken into account. Twelve different girders with heights of 60, 75, 90, 100, 110, 120, 130, 140, 150, 160, 170 and 180 cm, which are frequently used in Turkey, were chosen as girder type. The analyses of the superstructure of prestressed concrete I girder bridge was conducted with I-CAD software. In the analyses AASHTO LRFD (2012) conditions were taken into account a great extent. The dead loads of the structural and non-structural elements forming the bridge superstructure, prestressing force, standard truck load, equivalent lane load and pedestrian load were taken into consideration. HL93, design truck of AASHTO and also H30S24 design truck of Turkish Code were selected as vehicular live load. The allowable concrete stress limit, the number of prestressed strands, the number of debonded strands and the deflection parameters obtained from analyses were compared with the limit values found in AASHTO LRFD (2012) to determine the suitability of the girders. At the end of the study maximum span length of girders and equation using for calculation for minimum depth of the superstructure of prestressed concrete I-girder bridge were proposed.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.90-93
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• 2002

In particle radiotherapy, a shape of the beam to conform the irradiation field is statically defined by the compensator, collimator and potal devices at the outside of the patient body. However the target such as lung or liver cancer moves along with respiration. This increases the irradiated volume of normal tissue. Prior discussions about organ motions along with respiration have been mainly focused on inferior-superior movement that was usually perpendicular to beam axis. On the other hand, the change of the target depth along the beam axis is very important especially in particle radiotherapy, because the range end of beam (Bragg peak) is so sharp as to be matched to distal edge of the target. In treatment planning, the range of the particle beam inside the body is calculated using a calibration curve relating CT number and water equivalent path length (WEL) to correct the inhomogeneities of tissues. The variation in CT number along the beam path would cause the uncertainties of range calculation at treatment planning for particle radiotherapy. To estimate the uncertainties of the range calculation associated with patient breathing, we proposed the method using sequential CT images with respiration waveform, and analyzed organ motions and WELs at patients that had lung or liver cancer. The variation of the depth along the beam path was presented in WEL rather than geometrical length. In analyzed cases, WELs around the diaphragm were remarkably changed depending on the respiration, and the magnitude of these WEL variations was almost comparable to inferior-superior movement of diaphragm. The variation of WEL around the lung was influenced by heartbeat.

• Fashion & Textile Research Journal
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• v.15 no.4
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• pp.514-522
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• 2013

This study reviews the principles for the techniques of Impressionist paintings as well as analyzed contemporary fashion designs with a focus on a motif-building technique based on the laws of a screen equivalent as a visual formative approach. We provide design principles based on fashion design painting techniques. Previous research on the laws of the screen equivalent of Impressionist paintings were studied and a qualitative analysis was conducted on fashion design cases from 2011, 2012 S/S and F/W collections. The analysis resulted in the following outcomes. First, the development of new motifs were found directly correlated to the creativity of design if it was a motif-building design. Second, in the selected fashion design cases, cutting lines and details were covered by motifs and their shapes collapsed in regards to overall visual uniformity so that specific details were hard to identify. Third, clothing shapes are recognized the changing colors of motifs and not through construction pattern lines; therefore, the expressions of diverse visual forms were available without being disturbed by construction pattern lines. This is deemed equivalent to an Impressionist painting style that depicts shapes with colors instead of lines. Lastly, the cases covered in this study have created new visual aspects that replace the stereoscopic spatial depth of clothes with a 'sensuous surface'. The pleasures derived from the sensuous surface are deemed equivalent to the visual pleasures created by Impressionist paintings.