• Ocean Systems Engineering
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• 제5권3호
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• pp.221-243
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• 2015

This paper compares simplified and finite element method (FEM) models for tower and blade in dynamic coupled analysis of floating wind turbine. A SPAR type wind turbine with catenary mooring lines is considered in numerical analysis. Floating body equation is derived using boundary element method (BEM) and convolution. Equations for mooring line, tower and blade are formulated with theories of catenary, elastic beam and aerodynamic rotating beam, respectively and FEM is applied in the formulation. By combining the equations, coupled solutions are calculated. Tower or blade may be assumed rigid or lumped body for simplicity in modeling. By comparing floating body motions, mooring line tensions and tower stresses with the simple model and original FEM model, the effect of including or neglecting elastic, rotating and aerodynamic behavior of tower and blade is discussed.

• 산업경영시스템학회지
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• 제23권60호
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• pp.73-81
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• 2000

The testing processes for VLSI finished devices are considerably complex because they require different types of ATE to be linked together. Due to the interaction effect between two or more linked ATEs, it is difficult to trace down the cause of the unexpected longer ATE setup time and random yields, which frequently occur in the VLSI circuit-testing laboratory. The goal of this paper is to develop and demonstrate the methodology designed to eliminate the possible interaction factors that might affect the random yields and/or unexpected longer setup time as well as increase the productivity. The statistical method such as design of experiment or multivariate analysis cannot be applied to the final testing floor here directly due to the environmental constraints. Expanded product data information (PDI) is constructed by combining product data information and ATE control information. An architecture utilizing expanded PDI is designed, which enables the engineer to conduct statistical approach investigation and reduce the setup time, as well as increase yield.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.303-308
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• 2008

Directly modulated fiber-optic links generally suffer higher link loss and larger signal distortion than externally modulated links. These result from the electron-photon conversion loss and laser modulation dynamics. As a method to overcome the drawbacks, we have experimentally demonstrated the RF performance of directly modulated, ultra-strong injection-locked gain-lever distributed Bragg reflector (DBR) lasers. The free-running DBR lasers exhibit an improved amplitude modulation efficiency of 12.4 dB under gain-lever modulation at the expense of linearity. By combining gain-lever modulation with ultra-strong optical injection locking, we can gain the benefits of both improved modulation efficiency from the gain-lever effect, plus improved linearity from injection locking. Using an injection ratio of R=11 dB, a 23.4-dB improvement in amplitude response and an 18-dB improvement in spurious-free dynamic range have been achieved.

• Elastomers and Composites
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• 제54권1호
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• pp.40-53
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• 2019

The physical properties of chloroprene rubber (CR) compounds reinforced with networked silicas were investigated by comparing them to those reinforced with conventional silica to observe the effect of the organic connection bonds combining silica particles on their cure, tensile, and aging performance. The introduction of networked silica to CR increase in silica content to 80 phr in rubber, while the content of conventional silica was limited to 60 phr. The CR compounds reinforced with networked silica showed higher resistance to combustion. The gradual increases in delta torque, Mooney viscosity, and modulus of silica-filled CR compounds with silica content were mainly attributed to the specific interaction between the chlorine atoms of CR and the hydroxyl groups of silica. The CR compounds reinforced with networked silica showed low compression set and heat build-up and maintained their high modulus even after thermal, oil, and ozone aging.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2019년도 춘계학술대회
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• pp.286-287
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• 2019

In this paper, we consider an amplify-and-forward (AF) full duplex (FD) massive-antenna relay (or base station) aiding communication between K single-antenna source and destination pairs whose transmissions are overheard by one single-antenna eavesdropper. Maximum ratio combining (MRC) and maximum ratio transmission (MRT) processing is employed at the relay. The secrecy performance of the system is then derived with both relay and destination being equipped with low resolution analog-to-digital converters (ADCs). The results show the detrimental effect of the eavesdropper's presence on the sum rate of the system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5382-5403
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• 2018

In this paper, for a spectrum sensing purpose, we heuristically established a test statistic (TS) from a sample covariance matrix (SCM) for multiple antennas based cognitive radio. The TS is formulated as a scaled-energy which is calculated as a sum of scaled diagonal entries of a SCM; each of the diagonal entries of a SCM scaled by corresponding row's Euclidean norm. On the top of that, by combining theoretical results together with simulation observations, we have approximated a decision threshold of the TS which does not need prior knowledge of noise power and primary user signal. Furthermore, simulation results - which are obtained in a fading environment and in a spatially correlating channel model - show that the proposed method stands effect of noise power mismatch (non-uniform noise power) and has significant performance improvement compared with state-of-the-art test statistics.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1663-1674
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• 2018

We propose the Poynting vector analysis of the air mode in a top-emitting organic light-emitting diode (OLED) by combining the transfer matrix method and dipole source term. The spatial profiles of the time-averaged optical power flow of the air mode are calculated inside and outside the multilayer structure of the OLED with respect to the thickness of the semi-transparent top cathode and capping layer (CPL). We elucidate how the micro-cavity effect controlled by the thickness variation of the semi-transparent top cathode or CPL affects the internal optical power and absorption loss inside the OLED multilayer and the external optical power coupled into the air. When the calculated absorption loss and external power obtained by the proposed Poynting vector and currently-used point dipole models are compared, two calculation results are identical, which demonstrates the validity of the two models.

• 소성∙가공
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• 제30권3호
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• pp.149-156
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• 2021

Fine blanking is a high-precision process combining principles of metal stamping and cold forming. Unlike conventional metal stamping, fine blanking uses a special triple action such as V-ring force, counter force, shearing force. This study performed the effect of pocket-shaped compression molding on the mold life of the fine blanking using the 7.4mm thick SM45C material. In order to determine the lifespan of the punch and die in the fine blanking molds, a trial mold was manufactured and various punch materials were selected to perform the mold life test. A study on the life of a fine blanking mold by applying a thick plate material was experimentally performed through a mold test.

• International Journal of Advanced Culture Technology
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• 제10권4호
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• pp.403-411
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• 2022

Appearance management is evolving as a means of self-expression or as a way of expressing one's individuality. In particular, hairstyle is the most important part of a person's appearance and accounts for 70% of the appearance. Improving people's appearance by changing their hairstyle gives them confidence. Among them, the fringe hair style plays an important role in determining the first impression and reflects the trend. Fringe is shorter and simpler than general hair treatment, but even these small treatments have the effect of changing the impression, so women are trying to transform into a fringe hair style. A previous study was conducted on four lines classified: round, heart, square, and triangular. In this study, we added them to define 5 hairlines and created them by combining each hairline. that have been produced 5 fringe hair styles that suit the shape of the face. It is expected that the results of this study will be used as educational materials for hair line and fringe hair styles in the field, contributing to the beauty industry.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권1호
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• pp.60-79
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• 2022

The U-Net architecture-based segmentation models attained remarkable performance in numerous medical image segmentation missions like skin lesion segmentation. Nevertheless, the resolution gradually decreases and the loss of spatial information increases with deeper network. The fusion of adjacent layers is not enough to make up for the lost spatial information, thus resulting in errors of segmentation boundary so as to decline the accuracy of segmentation. To tackle the issue, we propose a new deep learning-based segmentation model. In the decoding stage, the feature channels of each decoding unit are concatenated with all the feature channels of the upper coding unit. Which is done in order to ensure the segmentation effect by integrating spatial and semantic information, and promotes the robustness and generalization of our model by combining the atrous spatial pyramid pooling (ASPP) module and channel attention module (CAM). Extensive experiments on ISIC2016 and ISIC2017 common datasets proved that our model implements well and outperforms compared segmentation models for skin lesion segmentation.