• Advances in concrete construction
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• v.14 no.2
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• pp.79-92
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• 2022

The amount and configuration of transverse reinforcement are known as critical parameters that significantly affect the lateral confinement of concrete, the ductility capacity, and the plastic hinge length of RC columns. Based on test results, this study investigated the effect of the three variables on structural indexes such as neutral axis depth, lateral expansion of concrete, and ductility capacity. Five reinforced concrete column specimens were tested under cyclic flexure and shear while simultaneously subjected to a constant axial load. The columns were reinforced by two types of reinforcing steel: rectangular hoops and spiral type reinforcing bars. The variables in the test program were the shape, diameter, and yield strength of transverse reinforcement. The interactive influence of the amount of transverse reinforcement on the structural indexes was evaluated. Test results showed that when amounts of transverse reinforcement were similar, and yield strength of transverse reinforcement was 600 MPa or less, the neutral axis depth of a column with spiral type reinforcing bars was reduced by 28% compared with that of a column reinforced by existing rectangular hoops at peak strength. While the diagonal elements of spiral-type reinforcing bars significantly contributed to the lateral confinement of concrete, the strain of diagonal elements decreased with increases of their yield strength. It was confirmed that shapes of transverse reinforcement significantly affected the lateral confinement of concrete adjacent to plastic hinges. Transverse reinforcement with a yield strength exceeding 600 MPa, however, increased the neutral axis depth of normal-strength concrete columns at peak strength, resulting in reductions in ductility and energy dissipation capacity.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.4
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• pp.52-66
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• 2003

Generally we have difficulty in removing oil using mechanical devices because recovery rate and recovery efficiency decrease remarkably when operating in thin oil films or in oils of very high viscosity In the Present study a series of experiments were carried out to study the effect of operating conditions on the rate of recovery for the spilled oil using a drum type skimmer. For each set of experiments depth of immersion, oil film thickness and the circumferential speeds were varied systematically to find the effects on the recovery rate. The results shows that recovery rate is dependent on the contact angle for the depth of immersion and the highest rate of oil recovery shows in the case of a contact angle of 45°(h/d=0.15). For the removal of spilled oil the optimal circumferential speed can be found as the critical value to reach the saturated recovery rate for a given oil film thickness and depth of immersion. Even in thin oil thickness we have enough recovery rate and recovery efficiency within critical circumferential speed this way.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.631-642
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• 2013

The standard CPT(Cone Penetration Test), which can be easily performed to investigate in-situ soil engineering properties, has been widely used. CPT are also widely being utilized in centrifuge model tests. In this study, a miniature cone with 10mm diameter was developed and its applicability in the centrifuge was evaluated. The developed miniature cone was equipped with a four degree-of-freedom in-flight robot. A series of cone penetration tests was performed under four centrifuge acceleration levels. As results, the cone resistances measured at the same confining stress within shallow penetration depth were affected by the centrifugal accelerations. The critical depth was proportional to the cone diameter and relative density. Cone resistances results below the critical depth and soil parameters obtained from the laboratory tests were compared with those by previously proposed empirical relations.

• Tribology and Lubricants
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• v.13 no.2
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• pp.96-104
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• 1997

This paper was focused on the wear characteristics of ion-nitrided metal and with ion-nitride processing, which is basically concerned with the effects of carbon content in workpiece and added carbon content gas atmosphere on the best wear performance. Increased carbon content in workpiece increases compound layer thickness, but decreases diffusion layer thickness. On the other hand, a small optimal amount of carbon content in gas atmosphere increase compound layer thickness as well as diffusion layer thickness and hardness. Wear tests show that the compound layer of ion-nitrided metal reduces wear rate when the applied wear load is small. However, as the load becomes large, the existence of compound layer tends to increase wear rate. Compressive residual stress at the compound layer is the largest at the compound layer, and decreases as the depth from the surface increases. It is found in the analysis that under small applied load, the critical depth where voids and cracks may be created and propagated is located at the compound layer, so that the adhesive wear is created and the existence of compound layer reduces the amount of wear. When the load becomes large, the critical depth is located below the compound layer and delamination, which may explained by surface deformation, crack nucleation and propagation, is created and the existence of compound layer increases wear rate. For the compound layer, at added carbon contents of 0 percent and 0.5 at. percent, the $\varepsilon$ monophase is predominant. But at 0.7 at. percent added carbon, the $\varepsilon$ monophase formation tends to be severely inhibited and r' and $Fe_3C$ polyphase formation becomes dominant. This increased hard $\varepsilon$ phase layer was observed to be more beneficial in reducing friction and wear.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.114-121
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• 1997

Helical anchors are foundation structure that designed to resist uplift loads are installed by applying in load to shaft while rotating it into the ground. These can be a cost effective means of proving tension anchorage for foundation where soil conditions permit their installation because of ease of installation. At present time, tapered helical anchors are commonly used to carry uplift loads. The uplift capacity includes the following factors : the height of overburden above the top helix, the resistant along a cylinder, the weight of the soil in the cylinder and suction force. In order to make clear behavior characteristics of helical anchors with pullout, model tests were conducted with respect to various embedment depth, space of helix, shape of helix. Based on the experimental study, the following conclusions are drawn. 1) The uplift capacity of multi helical anchors increase with embedment ratio of anchors The increase is smooth after critical uplift capacity. 2) Critical breakout factors and critical embedment ratio of multi helical anchor exist 7∼8, 4∼6 respectively. 3) Variation of uplift capacity with helix spaces show down after S/D=5. 4) Critical breakout factors of helical anchor in the laboratory test are similar to Das's theory.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.7
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• pp.391-401
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• 2020

The objective of this study is to prioritize the Total Quality Management (TQM) factors based on fuzzy Analytical Hierarchy Process (AHP) method in Vietnamese supporting industries. Through an in-depth literature review, eight criteria were identified. These criteria were then divided into 32 sub-criteria. The fuzzy AHP is used to determine the percent weightings of eight categories of performance criteria that were identified via a review of the quality-management literature. These criteria include management commitment, role of the quality department, training and education, continuous improvement, quality policies, quality data and reporting, communication to improve quality, and customer satisfaction orientation. An empirical analysis of the criteria of each stage using the fuzzy AHP methodology and the expert opinion of quality management are used to evaluate the percent weightings of the criteria and sub-criteria that are synonymous with TQM implementation. The results showed that management commitment is the most critical factor; among sub-criteria, supports and responsibilities of top management is the most important. The study also identified the rank order of critical success factors of TQM. The findings suggest a generic hierarchy model for organizations to prioritize the critical factors and formulate strategies for implementing TQM in supporting industries, as well as other industries in Vietnam.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.1
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• pp.91-99
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• 2017

Domestically developed concrete storage casks include an internal canister to maintain the confinement integrity of radio-active materials. In this study, we analyzed the depth of flaws caused by loads that propagate canister weld cracks under normal, off-normal and accident conditions, and evaluated the maximum allowable weld flaw depth needed to secure the structural integrity of the canister weld and to reduce the welding time of the internal canister lid of the concrete storage cask. Structural analyses for normal, off-normal and accident conditions were performed using the general-purpose finite element analysis program ABAQUS; the allowable flaw depth was assessed according to ASME B&PV Code Section XI. Evaluation results revealed an allowable canister weld flaw depth of 18.75 mm for the concrete storage cask, which satisfies the critical flaw depth recommended in NUREG-1536.

• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.302-307
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• 2019

In modern Anti-Submarine Warfare, there are various ways to locate a submarine in a two-dimensional space. For more effective tracking and attack against a submarine the depth of the target is a critical factor. However, it has been difficult to find out the depth of a submarine until now. In this paper a possible solution to the depth estimation of submarines is proposed utilizing DIFAR (Directional Frequency Analysis and Recording) sonobuoy information such as contact bearings at or prior to CPA (Closest Point of Approach) and the target's Doppler signals. The relative depth of the target is determined by applying the Pythagorean theorem to the slant range and horizontal range between the target and the hydrophone of a DIFAR sonobuoy. The slant range is calculated using the Doppler shift and the target's velocity. the horizontal range can be obtained by applying a simple trigonometric function for two consecutive contact bearings and the travel distance of the target. The simulation results show that the algorithm is subject to an elevation angle, which is determined by the relative depth and horizontal distance between the sonobuoy and target, and that a precise measurement of the Doppler shift is crucial.

• Computational Structural Engineering
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• v.9 no.4
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• pp.189-198
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• 1996

The fracture behaviour of concrete gravity dam mainly due to uplift pressure acting at the crack face was studied. Triangular type and parabolic type distribution of the uplift pressure including uniform type were first considered in case of calculating stress intensity factor(SIF) by the surface integral method. Second, the directions of crack propagation according to the uplift pressure distribution were pursued by FRANC(FRacture ANalysis Code). Third, critical crack lengths according to the uplift pressure distribution under the overflow depth were calculated. The SIF values obtained from the surface integral method were compared with those by FRANC and relatively good agrements could be obtained between both of them. And it could be seen that the direction of crack propagation in case of triangular pressure distribution was a little benter to the dam base than the one by the uniform type. Maximum critical crack lengths under the overflow depth were obtained at about 2/5-1/2 of the dam height.

• Journal of Broadcast Engineering
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• v.21 no.6
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• pp.957-964
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• 2016

Acquisition of reliable depth maps is a critical requirement in many applications such as 3D videos and free-viewpoint TV. Depth information can be obtained from the object directly using physical sensors, such as infrared ray (IR) sensors. Recently, Time-of-Flight (ToF) range camera including KINECT depth camera became popular alternatives for dense depth sensing. Although ToF cameras can capture depth information for object in real time, but are noisy and subject to low resolutions. Recently, filter-based depth up-sampling algorithms such as joint bilateral upsampling (JBU) and noise-aware filter for depth up-sampling (NAFDU) have been proposed to get high quality depth information. However, these methods often lead to texture copying in the upsampled depth map. To overcome this limitation, we formulate a convex optimization problem using higher order regularization for depth map upsampling. We decrease the texture copying problem of the upsampled depth map by using edge weighting term that chosen by the edge information. Experimental results have shown that our scheme produced more reliable depth maps compared with previous methods.