• Steel and Composite Structures
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• v.34 no.5
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• pp.671-679
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• 2020

The new energy-based criterion, named Reinforcement Strain Energy Density (ReiSED), is proposed to investigate the fracture behavior of the cracked orthotropic materials in which the crack is embedded in the matrix along the fibers. ReiSED is an extension of the well-known minimum strain energy density criterion. The concept of the reinforced isotropic solid as an advantageous model is the basis of the proposed mixed-mode I/II criterion. This model introduces fibers as reinforcements of the isotropic matrix in orthotropic materials. The effects of fibers are qualified by defining reinforcement coefficients at tension and shear modes. These coefficients, called Reduced Stress (ReSt), provide the possibility of encompassing the fiber fraction in a fracture criterion for the first time. Comparing ReiSED fracture limit curve with experimental data proves the high efficiency of this criterion to predict the fracture behavior of orthotropic materials.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.5
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• pp.109-114
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• 2011

In this paper, we apply a context awareness based on Gaussian mixture model (GMM) to a sound reinforcement for hearing impaired. In our approach, the harmful sound amplified through the sound reinforcement algorithm according to context awareness based on GMM which is constructed as Mel-frequency cepstral coefficients (MFCC) feature vector from sound data. According to the experimental results, the proposed approach is found to be effective in the various acoustic environments.

• Geomechanics and Engineering
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• v.14 no.1
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• pp.71-81
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• 2018

Soils are mostly nonhomogeneous and anisotropic in nature. In this study, nonhomogeneity and anisotropy of soil are taken into consideration by assuming that the cohesion increases with depth linearly and also varies with respect to direction at a particular point. A three-dimensional rotational failure mechanism is adopted, and then a three-dimensional stability analysis of slope is carried out with the failure surface in the shape of a curvilinear cone in virtue of the limit analysis method. A quasistatic approach is used to develop stability charts in nonhomogeneous and anisotropic soils. One can easily read the safety factors from the charts without the need for iterative procedures for safety factors calculation. The charts are of practical importance to prevent a plane failure in excavation slope whether it is physically constrained or not. Then the most suitable location of piles within the reinforced slope in nonhomogeneous and anisotropic soils is explored, as well as the interactions of nonhomogeneous and anisotropic coefficients on pile reinforcement effects. The results indicate that piles are more effective when they are located between the middle and the crest of the slope, and the nonhomogeneous coefficient as well as the anisotropic coefficient will not only influence the most suitable location for piles but also affect the calculated safety factor of existing reinforced slope. In addition, the two coefficients will interact with each other on the effect on slope reinforcement.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.3
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• pp.242-249
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• 2017

A design system for doubler reinforcement of the ship plate members subjected to in-plane shear and biaxial compressive loads was developed. This design system of doubler reinforcement on ship plate members established by design supporting system and this system was based on the buckling evaluation process of ship plate members for these in-plane loads. Each design parameters were suggested by equations as the form of influence coefficients for the doubler reinforcement subjected to the various in-plane loads including shear load. Strength of doubler plate member reinforced on the plate member could be suggested by the equivalent flat plate thickness after the consideration of corelation equations in the design system of doubler reinforcement. Level of strength recovery of ship plate members for these in-plane loads according to the local reinforcement by doubler could be suggested by use of this design system in the initial repair design stage of shipyards.

• Geomechanics and Engineering
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• v.35 no.5
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• pp.555-570
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• 2023

In the current study, a series of experimental and analytical evaluations were performed to introduce the horizontal pseudo static coefficient (kh) as a function of the wall configuration and the reinforcement type for analyzing reinforced soil walls. For this purpose, eight shaking table tests were performed on reduced-scale models of integrated and two-tiered walls reinforced by metal strip and geogrid to determine the distribution of dynamic lateral pressure in the walls. Then, the physical models were analyzed using Mononobe-Okabe method to estimate the value of kh required to establish the dynamic lateral pressures similar to those observed in shaking table tests. Based on the results, the horizontal pseudo static coefficient and the position of resultant lateral force (R) were introduced as a function of the horizontal peak ground acceleration (HPGA), the wall configuration, the reinforcement type as well as maximum wall displacement.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.8 no.1
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• pp.51-68
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• 2001

The purpose of this study was to explain the relationship between smoking status, smoking behavior and hardiness in university students in Gangnung City. The subjects were a convenience sample of 315 students. The data were collected by a questionnaire given to the students between May 22 to June 2, 2000. An instrument developed by Akers & Gang(1996) and translated by Sohn, Jung-Nam(1999) was used in this study to measure definition of smoking, differential reinforcement of smoking and smoking behavior. The differential peer association scale developed Krohn et al.(1982) and translated by Sohn, Jung-Nam(1999), and the hardiness scale developed by Pollock(1984) and translated by Suh, Mun-Sa(1988) were also used. The data were analyzed using the SAS/PC+ Program and included descriptive statistics, t-test, ANOVA, and Spearman correlation coefficients. The results of this study are as follows : 1. The smoking rate for university students was 50.5% of which 44.7% started smoking in high school. 2. The mean score for level of hardiness was $3.14{\pm}0.43$ 3. The mean score for smoking behavior was as follows : 1) The mean score for the neutralizing definition was $2.16{\pm}0.57$ 2) The mean score for the negative definition was $2.37{\pm}0.71$ 3) The mean score for the positive differential reinforcement was $1.89{\pm}0.63$ 4) The mean score for the negative differential reinforcement was $2.96{\pm}0.64$ 5) The mean score for the differential peer association was $2.67{\pm}1.05$ 4. The data showed positive correlations between hardiness and the neutralizing definition(r=.1951, P<.001), between hardiness and the positive differential reinforcement(r=.1128, P<.05), between hardiness and the amount of smoking per day(r=.1452, P<.05) between the neutralizing definition and positive differential reinforcement(r=.4212, P<.0001), between the neutralizing definition and differential peer association(r=.1856, P<.001), between the neutralizing definition and age at smoking initiation(r=.1582, P<.05), between the negative definition and negative differential reinforcement(r=.2985, P<.0001), between the positive differential reinforcement and differential peer association(r=.3451, P<.0001), between positive differential reinforcement and the amount of smoking per day(r=.4431, P<.0001), between differential peer association and the duration of smoking(r=.2789, P<.0001), between differential peer association and the amount of smoking per day(r=.5410, P<.0001), between the duration of smoking and the amount of smoking per day(r=.4245, P<.0001). The data showed negative correlations between the neutralizing definition and the negative definition(r=-.2065, P<.001) between the neutralizing definition and negative differential reinforcement(r=-.3943, P<.0001) between the neutralizing definition and duration of smoking(r=-.1957, P<.05), between the negative definition and positive differential reinforcement(r=-.2093, P<.001), between the negative definition and the amount of smoking per day(r=-.2282, P<.001), between positive differential reinforcement and negative differential reinforcement(r=-.5555, P<.0001) between negative differential reinforcement and differential peer association(r=-.3653, P<.0001), between negative differential reinforcement and the amount of smoking per day(r=-.4570, P<.0001), between the age at smoking initiation and the duration of smoking(r=-.4594, P<.0001).

• Structural Engineering and Mechanics
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• v.5 no.4
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• pp.355-368
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• 1997

Fiber reinforced plastic (FRP) rods are used as reinforcement (prestressed or not) to concrete. FRP composites can also be combined with steel to form hybrid reinforcing rods that take advantage of the properties of both materials. In order to effectively utilize these rods, their bond behavior with concrete must be understood. The objective of this study is to characterize and model the bond behavior of hybrid FRP rods made with epoxy-impregnated aramid or poly-vinyl alcohol FRP skins directly braided onto a steel core. The model closely examines the split failure of the concrete by quantifying the relationship between slip of the rods resulting transverse stress field in concrete. The model is used to derive coefficients of friction for these rods and, from these, their development length requirements. More testing is needed to confirm this model, but in the interim, it may serve as a design aide, allowing intelligent decisions regarding concrete cover and development length. As such, this model has helped to explain and predict some experimental data from concentric pull-out tests of hybrid FRP rods.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.123-132
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• 2021

In order for the underwater vehicle to perform various tasks, it is important to control the depth, course, and roll of the underwater vehicle. To design such a controller, it is necessary to construct a dynamic model of the underwater vehicle and select the appropriate hydrodynamic coefficients. For the controller design, since the dynamic model is linearized assuming a limited operating range, the control performance in the steady state is well satisfied, but the control performance in the transient state may be unstable. In this paper, in order to overcome the problems of the existing controller design, we propose a A2C(Advantage Actor-Critic) based roll controller for underwater vehicle with stable learning performance in a continuous space among reinforcement learning methods that can be learned through rewards for actions. The performance of the proposed A2C based roll controller is verified through simulation and compared with PID and Dueling DDQN based roll controllers.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.61-69
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• 2021

Recently, autonomous navigation technology is actively being developed due to the increasing demand of an unmanned surface vehicle(USV). Local planning is essential for the USV to safely reach its destination along paths. the dynamic window approach(DWA) algorithm is a well-known navigation scheme as a local path planning. However, the existing DWA algorithm does not consider path line tracking, and the fixed weight coefficient of the evaluation function, which is a core part, cannot provide flexible path planning for all situations. Therefore, in this paper, we propose a new DWA algorithm that can follow path lines in all situations. Fixed weight coefficients were trained using reinforcement learning(RL) which has been actively studied recently. We implemented the simulation and compared the existing DWA algorithm with the DWA algorithm proposed in this paper. As a result, we confirmed the effectiveness of the proposed algorithm.

• Structural Engineering and Mechanics
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• v.37 no.5
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• pp.529-542
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• 2011

Three dimensional solutions for free vibrations analysis of functionally graded fiber reinforced cylindrical panel are presented, using differential quadrature method (DQM). The orthotropic panel is simply supported at the edges and is assumed to have an arbitrary variation of reinforcement volume fraction in the radial direction. Suitable displacement functions that identically satisfy the simply supported boundary condition are used to reduce the equilibrium equations to a set of coupled ordinary differential equations with variable coefficients, which can be solved by differential quadrature method to obtain natural frequencies. The main contribution of this work is presenting useful results for continuous grading of fiber reinforcement in the thickness direction of a cylindrical panel and comparison with similar discrete laminate composite ones. Results indicate that significant improvement is found in natural frequency of a functionally graded fiber reinforced composite panel due to the reduction in spatial mismatch of material properties.