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Stabilized sub-grain and nano carbides-driven 1.2 GPa grade ultra-strong CrMnFeCoNi high-entropy alloy additively manufactured by laser powder bed fusion

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Journal of Materials Science & Technology 2022年第22期117卷 8-22页

作者： Young-kyun kim Kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea Korea Institute of Materials Science(kimS) Changwon 51508Republic of Korea

High-entropy alloys(HEAs)with interstitial atoms that are produced by additive manufacturing have gained intensive interest in the materials science community because of their suitability for constructing high-strength net-shape ***,a strategy to additionally enhance the strength of selective laser melted carbon-containing HEAs was *** as-built carbon-containing HEAs(C_(x)(Cr_(20)Mn_(20)Fe_(20)Co_(20)Ni_(20))_(100-x)(x=0.5 at.%,1.0 at.%,and 1.5 at.%))contain supersaturated carbon,and the extent of supersaturation increases as the carbon content *** subjected to aging treatment at 650°C for 1 h,the microstructure of the three alloys did not change at the grain ***,the microstructure at the sub-grain scale changed markedly,and these changes influenced the tensile properties and deformation *** particular,the tensile strength of aged 1.5C-HEA at 650°C was∼1.2 GPa at room temperature,which is higher than those reported for CrMnFeCoNi ***,the main deformation mechanism changed from deformation twinning to dislocation-mediated slip,resulting in much higher strain hardening capacity after the aging *** work led to the development of an alternative promising method that involves tailoring the microstructure,to enhance the mechanical properties of additively manufactured metallic materials that contain interstitial atoms.

关键词： Selective laser melting High-entropy alloy Carbon contents Aging Microstructure evolution Tensile property Deformation mechanism

Effect of carrier gas species on the microstructure and compressive deformation behaviors of ultra-strong pure copper manufactured by cold spray additive manufacturing

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Journal of Materials Science & Technology 2022年第2期97卷 264-271页

作者： Young-kyun kim Kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea

Cold spray(CS)which has recently become a promising additive manufacturing(AM)technology,was used to fabricate ultra-strong pure *** addition,the effects of carrier gas species on the microstructural characteristics,mechanical properties and deformation mechanisms were systemically *** CSAM copper manufactured with N_(2) carrier gas reveals a heterogeneous bimodal microstructure consisting of ultra-fine grains at the particle interface and relatively coarse grains in inner *** He carrier gas,a homogeneous grain structure consisting of ultra-fine grains in most areas was *** tests showed that N_(2) and He carrier gasses enabled ultra-high yield strengths of 340 and415 MPa,*** values are comparable to severely plastic deformed copper,which has extremely low ductility and shape *** the other hand,both samples showed a strain-softening phenomenon that does not commonly occur at room *** deformation microstructures revealed that dynamic recovery(DRV)and dynamic recrystallization(DRX)phenomena were generated despite being deformed at room *** on the above findings,the overall deformation mechanisms according to the carrier gas species in the CSAM copper manufacturing process were ***,the work hardening and softening behaviors of CSAM Cu are predicted by using a constitutive equation.

关键词： Cold spray additive manufacturing Carrier gas Pure Cu Mechanical properties Deformation behavior

1.45 GPa ultrastrong cryogenic strength with superior impact toughness in the in-situ nano oxide reinforced CrMnFeCoNi high-entropy alloy matrix nanocomposite manufactured by laser powder bed fusion

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Journal of Materials Science & Technology 2022年第2期97卷 10-19页

作者： Young-kyun kim Min-Chul kim Kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea Korea Atomic Energy Research Institute(KAERI) Daejeon 34057Republic of Korea

CrMnFeCoNi high-entropy alloys(HEAs)exhibit an excellent combination of tensile strength and ductility at cryogenic *** study led to the introduction of a new method for the development of high-performance CrMnFeCoNi HEAs at cryogenic temperatures by jointly utilizing additive manufacturing(AM)and the addition of interstitial *** interstitial oxygen present in the powder feedstock was transformed into beneficial nano-sized oxides during AM *** HEA nanocomposite fabricated using laser powder bed fusion(L-PBF)not only contains heterogeneous grains and substructures but also a high number density of nano-sized *** tensile results revealed that the L-PBF HEA nanocomposite has superior yield strengths of 0.77 GPa and 1.15 GPa,and tensile strengths of 0.92 GPa and 1.45 GPa at 298 K and 77 K,*** addition,the Charpy impact energies of the samples tested at 298 K and 77 K were measured as 176.2 J and 103.7 J,*** results indicate that the L-PBF HEA nanocomposite successfully overcomes the well-known strength-toughness *** tensile deformation microstructure contained a relatively large number of deformation twins(DTs)at cryogenic temperature,a possible consequence of the decrease in the stacking fault energy with decreasing *** the other hand,cracks were found to propagate along the grain boundaries at room temperature,whereas a transgranular crack was observed at cryogenic temperature in the specimens fractured as a result of the Charpy impact.

关键词： Laser powder bed fusion High-entropy alloy matrix nanocomposite Nano-oxide:cryogenic Tensile Impact toughness

Outlier Behavior Detection for Indoor Environment Based on t-SNE Clustering

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Computers, Materials & Continua 2021年第9期68卷 3725-3736页

作者： Shinjin Kang Soo kyun kim School of Games Hongik UniversitySejong30016Korea Department of Computer Engineering Jeju National UniversityJeju63243Korea

In this study,we propose a low-cost system that can detect the space outlier utilization of residents in an indoor *** focus on the users’app usage to analyze unusual behavior,especially in indoor *** is reflected in the behavioral analysis in that the frequency of using smartphones in personal spaces has recently *** system facilitates autonomous data collection from mobile app logs and Google app servers and generates a high-dimensional dataset that can detect outlier *** density-based spatial clustering of applications with noise(DBSCAN)algorithm was applied for effective singular movement *** analyze high-level mobile phone usage,the t-distributed stochastic neighbor embedding(t-SNE)algorithm was *** two clustering algorithms can effectively detect outlier behaviors in terms of movement and app usage in indoor *** experimental results showed that our system enables effective spatial behavioral analysis at a low cost when applied to logs collected in actual living ***,large volumes of data required for outlier detection can be easily *** system can automatically detect the unusual behavior of a user in an indoor *** particular,this study aims to reflect the recent trend of the increasing use of smartphones in indoor spaces to the behavioral analysis.

关键词： Outlier detection trajectory clustering behavior analysis app data smartphone

Design of Learning Media in Mixed Reality for Lao Education

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Computers, Materials & Continua 2020年第7期64卷 161-180页

作者： Kalaphath Kounlaxay Soo kyun kim Department of Game Engineering Pai Chai UniversityDaejeon35345Korea Department of Computer Engineering Jeju National UniversityJeju63243Korea

To improve and develop education systems,the communication between instructors and learners in a class during the learning process is of utmost *** the presentations of 3D models using mixed reality(MR)technology can be used to avoid misinterpretations of oral and 2D model *** an independent concept and MR applications,MR combines the excellent of each virtual reality(VR)and augmented reality(AR).This work aims to present the descriptions of MR systems,which include its devices,applications,and literature reviews and proposes computer vision tracking using the AR Toolkit Tracking *** focus of this work will be on creating 3D models and implementing in Unity 3D using the Vuforia SDK platform to develop VR and AR applications for architectural presentations.

关键词： Mixed reality virtual reality augmented reality Vuforia head-mounted displays.

Game Outlier Behavior Detection System Based on Dynamic Time Warp Algorithm

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Computer Modeling in Engineering & Sciences 2022年第4期131卷 219-237页

作者： Shinjin Kang Soo kyun kim School of Games Hongik UniversitySejong30016Korea Department of Computer Engineering Jeju National UniversityJeju63243Korea

This paper proposes a methodology for using multi-modal data in gameplay to detect outlier *** proposedmethodology collects,synchronizes,and quantifies time-series data fromwebcams,mouses,and *** expressions are varied on a one-dimensional pleasure axis,and changes in expression in the mouth and eye areas are detected ***,the keyboard and mouse input frequencies are tracked to determine the interaction intensity of ***,we apply a dynamic time warp algorithm to detect outlier *** detected outlier behavior graph patterns were the play patterns that the game designer did not intend or play patterns that differed greatly from those of other *** outlier patterns can provide game designers with feedback on the actual play experiences of users of the *** results can be applied to the game industry as game user experience analysis,enabling a quantitative evaluation of the excitement of a game.

关键词： Facial expression recognition webcam behavior analysis affective computing

q-Bernoulli polynomials and q-umbral calculus

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Science China Mathematics 2014年第9期57卷 1867-1874页

作者： kim Dae San kim Tae kyun Department of Mathematics Sogang University Department of Mathematics Kwangwoon University

In this paper,we investigate some properties of q-Bernoulli polynomials arising from q-umbral *** find a formula for expressing any polynomial as a linear combination of q-Bernoulli polynomials with explicit ***,we es... 详细信息

关键词： q-Bernoulli polynomial q-umbral calculus

Effect of soil pH on the sorption capacity of soil organic matter for polycyclic aromatic hydrocarbons in unsaturated soils

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Pedosphere 2023年第2期33卷 365-371页

作者： pil-Gon kim Abhrajyoti TARAFDAR Jung-Hwan KWON Division of Environmental Science and Ecological Engineering Korea University145 Anam-roSeongbuk-guSeoul 02841(Korea)

Sorption by soil organic matter(SOM)is considered the most important process affecting the bioavailability of hydrophobic organic chemicals(HOCs)in *** sorption capacity of SOM for HOCs is affected by many environmental *** this study,we investigated the effects of soil pH and water saturation level on HOC sorption capacity of SOM using batch sorption *** of soil organic carbon-water partition coefficient(K_(OC))of six selected polycyclic aromatic hydrocarbons(PAHs)were measured in an artificial soil under various soil pH and water saturation *** sampling was used to measure K_(OC)with polydimethylsiloxane as the sampling *** of soil pH,K_(OC)increased with increasing soil water saturation level for lower-molecular-weight *** contrast,K_(OC)decreased with increasing soil water saturation level for higher-molecular-weight *** some fluctuations,K_(OC)tended to decrease with increasing soil pH at all water saturation *** indicates that earlier studies on the effects of soil pH on K_(OC)under saturated conditions could be extended to unsaturated *** K_(OC)tendencies were reproduced in three different natural soils,suggesting that the effects of soil water saturation level and pH might be generalized,at least for *** PAH sorption capacity of SOM was found to be resilient under dynamic soil pH conditions,which can be used to adjust the effects of soil pH.

关键词： contaminated soil hydrophobic organic chemical partition coefficient passive sampling pollutant soil water saturation level

Voice activity detection based on deep belief networks using likelihood ratio

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Journal of Central South University 2016年第1期23卷 145-149页

作者： kim Sang-kyun PARK Young-Jin LEE Sangmin Department of Electronic Engineering Inha University Incheon 402-751 Korea Korea Electrotechnology Research Institute (KERI) 111 Hanggaul ro Sangrok Gu An-San shi Kyunggi Do 426-170 Korea Institute for Information and Electronics Research Inha University Incheon 402-751 Korea

A novel technique is proposed to improve the performance of voice activity detection(VAD) by using deep belief networks(DBN) with a likelihood ratio(LR). The likelihood ratio is derived from the speech and noise spectral components that are assumed to follow the Gaussian probability density function(PDF). The proposed algorithm employs DBN learning in order to classify voice activity by using the input signal to calculate the likelihood ratio. Experiments show that the proposed algorithm yields improved results in various noise environments, compared to the conventional VAD algorithms. Furthermore, the DBN based algorithm decreases the detection probability of error with [0.7, 2.6] compared to the support vector machine based algorithm.

关键词： voice activity detection likelihood ratio deep belief networks