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Influence of contact curvature on frictional energy dissipation under varying tangential loads

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Friction 2024年第2期12卷 363-374页

作者： Sumin baek Seunghun baek School of Mechanical Engineering Pusan National UniversityPusan 46241Republic of Korea

This study investigates the effect of contact surface curvatures on the friction response under varying tangential loadings using a finite element(FE)*** results showed that the geometry of the surface influences the contact force at the interface and reduces the friction effect through an unsteady distribution of the contact *** relationship between the friction effect,excitation,and contact surface shape was also examined,revealing a linear inverse relationship between the friction and *** findings provide a comprehensive understanding of the frictional interactions between elastic bodies and highlight the role of curvature as a design parameter for regulating the friction effect.

关键词： frictional contact curvelinear contact frictional energy dissipation contact curvature

On Multifractal of Cantor Dust

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Acta Mathematica Sinica,English Series 2009年第7期25卷 1175-1182页

作者： In-Soo baek Department of Mathematics Pusan University of Foreign Studies

We consider quasi-self-similar measures with respect to all real numbers on a Cantor dust. We define a local index function on the real numbers for each quasi-self-similar measure at each point in a Cantor dust, The value of the local index function at the real number zero for all the quasi-self-similar measures at each point is the weak local dimension of the point. We also define transformed measures of a quasi-self-similar measure which are closely related to the local index function. We compute the local dimensions of transformed measures of a quasi-self-similar measure to find the multifractal spectrum of the quasi-self-similar measure, Furthermore we give an essential example for the theorem of local dimension of transformed measure. In fact, our result is an ultimate generalization of that of a self- similar measure on a self-similar Cantor set. Furthermore the results also explain the recent results about weak local dimensions on a Cantor dust.

关键词： Cantor set Hansdorff dimension packing dimension quasi-self-similar measure local dimension

Experimental Investigation of Aerodynamic Performance due to Blade Tip Clearance in a Gas Turbine Rotor Cascade

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Journal of Thermal Science 2022年第1期31卷 173-178页

作者： CHUNG Jinmoo baek Seungchan HWANG Wontae Department of Mechanical Engineering Seoul National UniversitySeoul 08826Republic of Korea Institute of Advanced Machines and Design Seoul National UniversitySeoul 08826Republic of Korea Institute of Engineering Research Seoul National UniversitySeoul 08826Republic of Korea

This study examines how the complex flow structure within a gas turbine rotor affects aerodynamic loss. An unshrouded linear turbine cascade was built, and velocity and pressure fields were measured using a 5-hole probe. In order to elucidate the effect of tip clearance, the overall aerodynamic loss was evaluated by varying the tip clearance and examining the total pressure field for each case. The tip clearance was varied from 0% to 4.2% of blade span and the chord length based Reynolds number was fixed at 2×10^(5). For the case without tip clearance, a wake downstream of the blade trailing edge is observed, along with hub and tip passage vortices. These flow structures result in profile loss at the center of the blade span, and passage vortex related losses towards the hub and tip. As the tip clearance increases, a tip leakage vortex is formed, and it becomes stronger and eventually alters the tip passage vortex. Because of the interference of the secondary tip leakage flow with the main flow, the streamwise velocity decreases while the total pressure loss increases significantly by tenfold in the last 30% blade span region towards the tip for the 4.2% tip clearance case. It was additionally observed that the overall aerodynamic loss increases linearly with tip clearance.

关键词： gas turbine turbine cascade aerodynamic loss tip clearance tip leakage

Genus Polynomials of Cycles with Double Edges

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Acta Mathematica Sinica,English Series 2011年第3期27卷 595-606页

作者： Eunyoung baek Jongyook PARK Department of Mathematics Pohang University of Science and Technology Pohang 790-784 Korea

Two cellular embeddings i ： G→S and j ： G → S of a connected graph G into a closed orientable surface S are equivalent if there is an orientation-preserving surface homeomorphism h ： S → S such that hi = j. The genus polynomial of a graph G is defined by g[G]（x）=∞∑g=0agx^g, where ag is the number of equivalence classes of embeddings of G into the orientable surface Sg with g genera. In this paper, we compute the genus polynomial of a graph obtained from a cycle by replacing each edge by two multiple edges.

关键词： Embedding genus genus distribution genus polynomial

Explainable Anomaly Detection Using Vision Transformer Based SVDD

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Computers, Materials & Continua 2023年第3期74卷 6573-6586页

作者： Ji-Won baek Kyungyong Chung Department of Computer Science Kyonggi UniversitySuwon-si 16227Korea Division of AI Computer Science and Engineering Kyonggi UniversitySuwon-si 16227Korea

Explainable AI extracts a variety of patterns of data in the learning process and draws hidden information through the discovery of semantic *** is possible to offer the explainable basis of decision-making for inference *** the causality of risk factors that have an ambiguous association in big medical data,it is possible to increase transparency and reliability of explainable decision-making that helps to diagnose disease *** addition,the technique makes it possible to accurately predict disease risk for anomaly *** transformer for anomaly detection from image data makes classification through ***,in MLP,a vector value depends on patch sequence information,and thus a weight *** should solve the problem that there is a difference in the result value according to the change in the *** addition,since the deep learning model is a black box model,there is a problem that it is difficult to interpret the results determined by the ***,there is a need for an explainablemethod for the part where the disease *** solve the problem,this study proposes explainable anomaly detection using vision transformerbasedDeep Support Vector Data Description(SVDD).The proposed method applies the SVDD to solve the problem of MLP in which a result value is different depending on a weight change that is influenced by patch sequence information used in the vision *** order to draw the explainability of model results,it visualizes normal parts through *** health data,both medical staff and patients are able to identify abnormal parts *** addition,it is possible to improve the reliability of models and medical *** performance evaluation normal/abnormal classification accuracy and f-measure are evaluated,according to whether to apply *** Results The results of classification by applying the proposed SVDD are evaluated ***,through the proposed meth

关键词： Explainable AI anomaly detection vision transformer SVDD health care deep learning classification

Effect of Squeeze Cast Process Parameters on Fluidity of Hypereutectic Al-Si Alloy

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Journal of Materials Science & Technology 2008年第1期24卷 7-11页

作者： Jong-Kyu baek Hae-Wook Kwon School of Materials Science and Engineering Yeungnam University Gyeongsan 712-749 Korea

The effects of processing variables on the fluidity of hypereutectic Al-Si alloy melt during squeeze casting were *** maximum fluidity of Al-16.0%Si alloy during squeeze casting was obtained under the applied pressure of 30 *** fluidity increased with *** fluidity increased with silicon content in the range from 12.0% to 20.0%.That was decreased respectively by eutectic modification and primary silicon refinement.

关键词： Squeeze casting Al-alloy Fluidity Melt treatment

Wavelet Estimation in Heteroscedastic Model Under Censored Samples

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Acta Mathematica Sinica,English Series 2007年第12期23卷 2253-2268页

作者： Han Ying LIANG Jong IL baek Department of Mathematics Tongji University Shanghai 200092 P. R. China School of Mathematics & Informational Statistics and Institute of Basic Natural Science Wonkwang University Ik-San 570-749 South Korea

Consider the heteroscedastic regression model Yi = g（xi）＋ σiei, 1 ≤ i ≤ n, where σi^2 = f（ui）, here （xi, ui） being fixed design points, g and f being unknown functions defined on [0, 1], ei being independent random errors with mean zero. Assuming that Yi are censored randomly and the censored distribution function is known or unknown, we discuss the rates of strong uniformly convergence for wavelet estimators of g and f, respectively. Also, the asymptotic normality for the wavelet estimators of g is investigated.

关键词： censored sample heteroscedastic regression model wavelet estimator strong unform convergence rate asymptotic normality

A Novel Framework to Construct S-Box Quantum Circuits Using System Modeling: Application to 4-Bit S-Boxes

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 545-561页

作者： Yongjin Jeon Seungjun baek Jongsung Kim Department of Financial Information Security Kookmin UniversitySeoul02707Republic of Korea

Quantum computers accelerate many algorithms based on the superposition principle of quantum *** Grover algorithm provides significant performance to malicious users attacking symmetric key *** the performance of attacks using quantum computers depends on the efficiency of the quantum circuit of the encryption algorithms,research research on the implementation of quantum circuits is *** paper presents a new framework to construct quantum circuits of substitution boxes(S-boxes)using system *** model the quantum circuits of S-boxes using two layers:Toffoli and linear *** generate vector spaces based on the values of qubits used in the linear layers and apply them to find quantum *** framework finds the circuit bymatching elements of vector spaces generated fromthe input and output of a given S-box,using the forward search or themeet-in-the-middle *** developed a tool to apply this framework to 4-bit *** the 4-bit S-box quantum circuit construction tool LIGHTER-R only finds circuits that can be implemented with four qubits,the proposed tool achieves the circuits with five *** proposed tool can find quantum circuits of 4-bit odd permutations based on the controlled NOT,NOT,and Toffoli gates,whereas LIGHTER-R is unable to perform this task in the same *** expect this technique to become a critical step toward optimizing S-box quantum circuits.

关键词： System modeling quantum circuit S-box circuit quantum computer

Nucleation and growth behavior of coating film on Mg–Al–Zn alloy with different surface topographies via plasma electrolytic oxidation

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Journal of Magnesium and Alloys 2022年第8期10卷 2185-2192页

作者： Nisa Nashrah Sung Hun baek Young Gun Ko Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea

This work was made to investigate how nucleation and growth behavior of the coating film were affected by surface topographies of Mg–Al–Zn alloy substrate during the initial stage of plasma electrolytic oxidation(PEO).To satisfy this end,a single substrate was prepared by mechanical treatment exhibiting rough and smooth regions with an equal area on the *** rough region with prominent hills and grooves induced the breakdown of passive film,which was indicated by an early appearance of plasma discharge on the rough region since nucleation of coating film occurred preferentially around the ***,the coating film grown on the grooves was somewhat thicker and more porous than the film grown on the hills and smooth *** was due to the fact that the growth of the coating film was found to be localized in the presence of rough region,which was in line with the discharge ***,the nucleation and growth behavior during the initial stage of PEO will be discussed schematically on the basis of microstructural interpretation.

关键词： Mg alloy Surface roughness Plasma electrolytic oxidation Coating film