• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.17-21
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• 2022

A variety of techniques have been proposed in the literature for depth improvement in depth from focus method. Unfortunately, these techniques over-smooth the depth maps over the regions of depth discontinuities. In this paper, we propose a robust technique for improving the depth map by employing a nonconvex smoothness function that preserves the depth edges. In addition, the proposed technique exploits the mutual structures between the depth map and a guidance map. This guidance map is designed by taking the mean of image intensities in the image sequence. The depth map is updated iteratively till the nonconvex objective function converges. Experiments performed on real complex image sequences revealed the effectiveness of the proposed technique.

• The Journal of the Acoustical Society of Korea
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• v.28 no.2E
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• pp.51-59
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• 2009

Mutual radiation impedance becomes more important in the design and analysis of acoustic transducers for higher power, better beam pattern, and wider bandwidth at low frequency sonar systems. This review paper focused on literature survey about the researches of mutual radiation impedance in the acoustic transducer arrays over 60 years. The papers of mutual radiation impedance were summarized in terms of transducer array structures on various baffle geometries such as planar, cylindrical, spherical, conformal, spheroidal, and elliptic cylindrical arrays. Then the computation schemes of solving conventional quadruple integral in the definition of mutual radiation impedance were surveyed including spatial convolution method, which reduces the quadruple integral to a double integral for efficient computation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.234-242
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• 1987

The solution of shape design problems based on variational analysis has been approached by using the domain adaptive method. The objective of the structural shape design is to minimize the weight within a bound on local stress measure, or to minimize the maximum local stress measure within a bound on the weight. A derived optimality condition in both design problems requires that the unit mutual energy has constant value along the design boundary. However, the condition for constant stress on the design boundary was used in computation since the computed mutual energy oscillates severely on the boundary. A two step iteration scheme using domain adaptation was presented as a computational method to slove the example designs of elastic structures. It was also shown that remeshing by grid adaptation was effective to reduce oscillatory behavior on the design boundary.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.2
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• pp.1-11
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• 2005

The network structures of a hyperlinked environment can be a rich source of information about the contents of the environment and it provides effective means for understanding it. Recently, there have been a number of algorithms proposed analyzing hypertext link structure so as to determine the best authorities for a given topic or query. In this paper, we review the algorithm of mutual reinforcement relationship for finding hubs and authorities from World Wide Web, and suggest SHA, a new approach for link-structure analysis, which uses the relationships among a set of relative authoritative pages, a set of hub pages, and a set of super hub pages.

• Computers and Concrete
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• v.32 no.6
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• pp.615-623
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• 2023

Crack detection is an essential method to ensure the safety of dam concrete structures. Low-quality crack images of dam concrete structures limit the application of neural network methods in crack detection. This research proposes a modified attentional mechanism model to reduce the disturbance caused by uneven light, shadow, and water spots in crack images. Also, the focal loss function solves the small ratio of crack information. The dataset collects from the network, laboratory and actual inspection dataset of dam concrete structures. This research proposes a novel method for crack detection of dam concrete structures based on the U-Net neural network, namely AF-UNet. A mutual comparison of OTSU, Canny, region growing, DeepLab V3+, SegFormer, U-Net, and AF-UNet (proposed) verified the detection accuracy. A binocular camera detects cracks in the experimental scene. The smallest measurement width of the system is 0.27 mm. The potential goal is to achieve real-time detection and localization of cracks in dam concrete structures.

• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.6
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• pp.988-1001
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• 2018

The head and face are the most complicated structures of the human body. However, unlike apparel products, many of the head and face related products are produced in unisex or one-size-fits-all. Therefore, it is necessary to provide a practical analysis that reflects these size structures. This study analyzed head and face measurements of men, women, and both men and women; its purpose lying in clarifying the differences and commonalities between the measurements of men and women and discovering the possibility of integrating analysis on measurements of men and women. 3D face and head measurement data of men and women from 20 to 29 years-old from Size Korea's 6th human body size data were analyzed for this study. The mutual 9 factors were extracted as the results of the three factor analyses (both men and women) separately and men and women integrated. However in the cluster analysis based on the 9 factors, men and women showed mutual characteristics and different landscape in group types and distribution. The commonalities and differences between men and women observed in this study should be applied to the sizes of head and face products.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1127-1143
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• 2016

The pounding phenomenon in adjacent structures happens in severing earthquakes that can cause great damages. Connecting neighboring structures with active and semi-active control devices is an effective method to avoid mutual colliding between neighboring buildings. One of the most important issues in control systems is applying online control force. There will be a time delay if the prose of producing control force does not perform on time. This paper proposed a time-delay compensation method in coupled structures control, with semi-active Magnetorheological (MR) damper. This method based on Newmark's integration is adopted to mitigate the time-delay effect. In this study, Lyapunov's direct approach is employed to compute demanded voltage for MR dampers. Using Lyapunov's direct algorithm guarantees the system stability to design a controller based on feedback. Because of the strong nonlinearity of MR dampers, the equation of motion of coupled structures becomes an involved equation, and it is impossible to solve it with the common time step methods. In present paper modified Newmark-Beta integration based on the instantaneous optimal control algorithm, used to solve the involved equation. In this method, the response of a coupled system estimated base on optimal control force. Two MDOF structures with different degrees of freedom are finally considered as a numeric example. The numerical results show, the Newmark compensation is an efficient method to decrease the negative effect of time delay in coupled systems; furthermore, instantaneous optimal control algorithm can estimate the response of structures suitable.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.146-153
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• 2009

Recently, the common grounding systems are adapted in most large structures. Since the ground resistance is insufficient to evaluate the performance of grounding systems, it is needed to measure grounding impedance. Even though the methods of measuring grounding impedance of large grounding systems are presented in IEEE standard 81.2, but they have not been described in detail. In this paper, we present the accurate method of measuring grounding impedance based on the revised fall-of-potential method and measurement errors due to earth mutual resistance and ac mutual coupling depending on locating test electrodes at remote earth were examined for the 15[m]$\times$15[m] grounding grid. As a result, the measurement error due to earth mutual resistance is decreased when the distance to auxiliary electrodes increased. To get rid of measurement errors due to mutual coupling, the potential lead should be installed at a right angle to the current lead. When the angle between the potential and the current leads is an acute angle or an obtuse angle, the mutual couple voltage is positive or negative, respectively. Generally, the measurement errors due to mutual coupling with an obtuse angle route are lower than those with an acute angle route.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1487_1488
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• 2009

In these days, the common grounding systems are adapted in most large structures. In order to evaluate the performance of grounding system, it is needed to measure ground impedance. Measuring methods of ground impedance for a large scale grounding systems have not been yet presented in detail. In this paper, we analyze earth mutual resistance and mutual coupling of $15{\times}15m$ grounding grid in different arrangements of auxiliary electrode. As a results, the auxiliary electrodes are installed where the error rate due to earth mutual resistance is less than 5%. Also, the potential lead is installed at obtuse angle from the current lead and the overlapped length between potential lead and grounding grid are minimized.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1345-1356
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• 2014

The thermal behavior of power modules is an important criterion for the design of cooling systems and optimum thermal structure of these modules. An important consideration for high power and high frequency design is the spacing between semiconductor devices, substrate structure and influence of the boundary condition in the case. This study focuses on the thermal behavior of hybrid power modules to establish a simplified method that allows temperature estimation in different module components without decapsulation. This study resulted in a correction of the junction temperature values estimated from the transient thermal impedance of each component operating alone. The corrections depend on mutual thermal coupling between different chips of the hybrid structure. A new experimental technique for thermal mutual evaluation is presented. Notably, the classic analysis of thermal phenomena in these structures, which was independent of dissipated power magnitude and boundary conditions in the case, is incorrect.