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Friction 2023年第7期11卷 1292-1306页

作者： Kuk-Jin SEO Hyun-joon kim Dae-Eun kim Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Precision Mechanical Engineering Kyungpook National UniversitySangju 37224Republic of Korea Department of Advanced Science and Technology Convergence Kyungpook National UniversitySangju 37224Republic of Korea

This work shows that a soft,thin film comprising randomly aligned carbon nanotubes(CNTs)can reduce surface wear more effectively than a homogeneous thin film because of enhanced elastic recoverability and contact stress relief originating from its mesh *** investigate the wear characteristics of the mesh structure compared to those of the homogeneous thin film,multi-walled CNTs(MWCNTs)and diamond-like carbon(DLC)thin films were prepared to conduct nanoscale tribological experiments using the atomic force microscopy(AFM).The MWCNT thin film showed unmeasurably low wear compared with the DLC thin film under a certain range of normal *** demonstrate the wear reduction mechanism of the MWCNT thin film,its indentation and frictional behaviors were *** indentation behavior of the MWCNT thin film revealed repetitive elastic deformation with a wide strain range and a significantly lower elastic modulus than that of the DLC thin *** permanent deformation of the MWCNT thin film was observed through frictional experiments under relatively high normal load *** results are expected to provide insights into the design of highly wear-resistant surfaces using nanostructures.

关键词： carbon nanotube(CNT) thin film wear friction elastic recovery

Uncertainty analysis of flow rate measurement for multiphase flow using CFD

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Acta Mechanica Sinica 2015年第5期31卷 698-707页

作者： joon-Hyung kim Uk-Hee Jung Sung kim joon-Yong Yoon Young-Seok Choi Department of Mechanical Design Engineering Hanyang University Thermal & Fluid System R&BD Group Korea Institute of Industrial Technology Energy System Engineering University of Science and Technology

The venturi meter has an advantage in its use,because it can measure flow without being much affected by the type of the measured fluid or flow ***,it has excellent versatility and is being widely applied in many *** flow of a liquid containing air is a representative example of a multiphase flow and exhibits complex flow *** particular,the greater the gas volume fraction（GVF）,the more inhomogeneous the flow *** a result,using a venturi meter to measure the rate of a flow that has a high GVF generates an *** this study,the cause of the error occurred in measuring the flow rate for the multiphase flow when using the venturi meter for analysis by *** ensure the reliability of this study,the accuracy of the multiphase flow models for numerical analysis was verified through comparison between the calculated results of numerical analysis and the experimental *** a result,the Grace model,which is a multiphase flow model established by an experiment with water and air,was confirmed to have the highest ***,the characteristics of the internal flow Held about the multiphase flow analysis result generated by applying the Grace model were analyzed to find the cause of the uncertainty occurring when measuring the flow rate of the multiphase flow using the venturi meter.A phase separation phenomenon occurred due to a density difference of water and air inside the venturi,and flow inhomogeneity happened according to the flow velocity difference of each *** was confirmed that this flow inhomogeneity increased as the GVF increased due to the uncertainty of the flow measurement.

关键词： Multiphase flow Measurement Numerical analysis Venturi meter Gas volume fraction(GVF) Uncertainty Multiphase flow model Grace model

Hepatitis B virus mutations related to liver disease progression of Korean patients

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World Journal of Gastroenterology 2014年第2期20卷 460-467页

作者： Bum-joon kim Department of Biomedical Sciences Microbiology and ImmunologyLiver Research Instituteand Cancer Research InstituteCollege of MedicineSeoul National UniversitySeoul 110-799South Korea

Hepatitis B virus(HBV)infection is a global health problem and more than 350 million people worldwide are chronic carriers of the *** the recent dramatic decline in HBV chronic patients through successful programs of hepatitis B surface antigen vaccination,South Korea is still recognized as an endemic area of HBV *** infections in South Korea exhibit several distinct features in epidemiologic and clinical *** this review paper,we summarize the distinct HBV mutation patterns related to clinical severity and the molecular epidemiologic traits in Korean chronic patients based on previous ***,several lines of evidence,including our previous results,have led to the conclusion that a combination of the exclusive predominance of genotype C2,which is prone to mutations,the high prevalence of basal core promoter double mutations,and the presence of distinct immune responses against HBV proteins in the Korean population may generate the distinct HBV variants rarely or not encountered in other areas,which results in distinct clinical manifestations in Korean chronic *** may provide a novel insight into the relationships between clinical severity,HBV genotype distribution,and HBV naturally occurring variants.

关键词： Hepatitis B virus Mutation South Korea Hepatocellular carcinoma Genotype C2

Targeting the RAS/RAF/MAPK pathway for cancer therapy: from mechanism to clinical studies

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Signal Transduction and Targeted Therapy 2024年第1期9卷 173-210页

作者： Md Entaz Bahar Hyun joon kim Deok Ryong kim Department of Biochemistry and Convergence Medical Sciences and Institute of Medical Science Gyeongsang National UniversityCollege of MedicineJinjuSouth Korea Department of Anatomy and Convergence Medical Sciences and Institute of Medical Science Gyeongsang National UniversityCollege of MedicineJinjuSouth Korea

Metastatic dissemination of solid tumors,a leading cause of cancer-related mortality,underscores the urgent need for enhanced insights into the molecular and cellular mechanisms underlying metastasis,chemoresistance,and the mechanistic backgrounds of individuals whose cancers are prone to *** most prevalent signaling cascade governed by multi-kinase inhibitors is the mitogen-activated protein kinase(MAPK)pathway,encompassing the RAS–RAF–MAPK kinase(MEK)–extracellular signal-related kinase(ERK)*** kinase is a primary mediator of the MAPK pathway,responsible for the sequential activation of downstream targets,such as MEK and the transcription factor ERK,which control numerous cellular and physiological processes,including organism development,cell cycle control,cell proliferation and differentiation,cell survival,and *** in this signaling cascade are associated with diseases such as *** inhibitors(RAFi)combined with MEK blockers represent an FDAapproved therapeutic strategy for numerous RAF-mutant cancers,including melanoma,non-small cell lung carcinoma,and thyroid ***,the development of therapy resistance by cancer cells remains an important ***,an intracellular lysosome-dependent catabolic recycling process,plays a critical role in the development of RAFi resistance in ***,targeting RAF and autophagy could be novel treatment strategies for RAF-mutant *** this review,we delve deeper into the mechanistic insights surrounding RAF kinase signaling in tumorigenesis and ***,we explore and discuss the ongoing development of next-generation RAF inhibitors with enhanced therapeutic ***,this review sheds light on the functional interplay between RAF-targeted therapies and autophagy in cancer.

关键词： RAF insight mechanism

A Universal Activation Function for Deep Learning

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Computers, Materials & Continua 2023年第5期75卷 3553-3569页

作者： Seung-Yeon Hwang Jeong-joon kim Department of Computer Engineering Anyang UniversityAnyang-si14028Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14028Korea

Recently,deep learning has achieved remarkable results in fields that require human cognitive ability,learning ability,and reasoning *** functions are very important because they provide the ability of artificial neural networks to learn complex patterns through *** activation functions are being studied to solve problems such as vanishing gradients and dying nodes that may occur in the deep learning ***,it takes a lot of time and effort for researchers to use the existing activation function in their ***,in this paper,we propose a universal activation function(UA)so that researchers can easily create and apply various activation functions and improve the performance of neural *** can generate new types of activation functions as well as functions like traditional activation functions by properly adjusting three *** famous Convolutional Neural Network(CNN)and benchmark datasetwere used to evaluate the experimental performance of the UA proposed in this *** compared the performance of the artificial neural network to which the traditional activation function is applied and the artificial neural network to which theUA is *** addition,we evaluated the performance of the new activation function generated by adjusting the hyperparameters of *** experimental performance evaluation results showed that the classification performance of CNNs improved by up to 5%through the UA,although most of them showed similar performance to the traditional activation function.

关键词： Deep learning activation function convolutional neural network benchmark datasets universal activation function

Data Augmentation Using Contour Image for Convolutional Neural Network

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Computers, Materials & Continua 2023年第6期75卷 4669-4680页

作者： Seung-Yeon Hwang Jeong-joon kim Department of Computer Engineering Anyang UniversityAnyang-si14058Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14058Korea

With the development of artificial intelligence-related technologies such as deep learning,various organizations,including the government,are making various efforts to generate and manage big data for use in artificial ***,it is difficult to acquire big data due to various social problems and restrictions such as personal information *** are many problems in introducing technology in fields that do not have enough training data necessary to apply deep learning ***,this study proposes a mixed contour data augmentation technique,which is a data augmentation technique using contour images,to solve a problem caused by a lack of ***,a famous convolutional neural network(CNN)architecture,and CIFAR-10,a benchmark data set,are used for experimental performance evaluation to prove the superiority of the proposed *** to prove that high performance improvement can be achieved even with a small training dataset,the ratio of the training dataset was divided into 70%,50%,and 30%for comparative *** a result of applying the mixed contour data augmentation technique,it was possible to achieve a classification accuracy improvement of up to 4.64%and high accuracy even with a small amount of data *** addition,it is expected that the mixed contour data augmentation technique can be applied in various fields by proving the excellence of the proposed data augmentation technique using benchmark datasets.

关键词： Data augmentation image classification deep learning convolutional neural network mixed contour image benchmark dataset

A Deep Learning Hierarchical Ensemble for Remote Sensing Image Classification

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Computers, Materials & Continua 2022年第8期72卷 2649-2663页

作者： Seung-Yeon Hwang Jeong-joon kim Department of Computer Engineering Anyang UniversityAnyang-si14028Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14028Korea

Artificial intelligence,which has recently emerged with the rapid development of information technology,is drawing attention as a tool for solving various problems demanded by society and *** particular,convolutional neural networks(CNNs),a type of deep learning technology,are highlighted in computer vision fields,such as image classification and recognition and object *** these CNN models requires a large amount of data,and a lack of data can lead to performance degradation problems due to *** CNN architecture development and optimization studies become active,ensemble techniques have emerged to perform image classification by combining features extracted from multiple CNN *** this study,data augmentation and contour image extraction were performed to overcome the data shortage *** addition,we propose a hierarchical ensemble technique to achieve high image classification accuracy,even if trained from a small amount of ***,we trained the UCMerced land use dataset and the contour images for each image on pretrained VGGNet,GoogLeNet,ResNet,DenseNet,and *** then apply a hierarchical ensemble technique to the number of cases in which each model can be *** experiments were performed in cases where the proportion of training datasets was 30%,50%,and 70%,resulting in a performance improvement of up to 4.68%compared to the average accuracy of the entire model.

关键词： Image classification deep learning CNNs hierarchical ensemble UC-Merced land use dataset contour image

Is the filamentary dark cloud GF 6 a star forming region?--Stability analysis and infrared properties

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Research in Astronomy and Astrophysics 2017年第12期17卷 77-88页

作者： Jaeheon kim Hyun-Goo kim Sang joon kim Bo Zhang Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Korea Astronomy and Space Science Institute Daejeon 34055Korea Department of Astronomy and Space Science Kyung Hee UniversityYongin 17104Korea

We present the results of mapping observations and stability analyses toward the filamentary dark cloud GF 6. We investigate the internal structures of a typical filamentary dark cloud GF 6 to know whether the filamentary dark cloud will form stars. We perform radio observations with both 12CO（J =1–0） and 13CO（J =1–0） emission lines to examine the mass distribution and its evolutionary *** 13CO gas column density map shows eight subclumps in the GF 6 region with sizes on a sub-pc scale. The resulting local thermodynamic equilibrium masses of all the subclumps are too low to form stars against the turbulent dissipation. We also investigate the properties of embedded infrared point sources to know whether they are newly formed stars. The infrared properties also indicate that these point sources are not related to star forming activities associated with GF 6. Both radio and infrared properties indicate that the filamentary dark cloud GF 6 is too light to contract gravitationally and will eventually be dissipated away.

关键词： ISM:clouds ISM:molecules radio lines:ISM infrared:ISM Instabilities Turbulence

DYNAMIC PROPERTIES OF AL-ALLOY FOAM BEAM DAMAGED BY COMPRESSIVE FATIGUE

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Acta Mechanica Solida Sinica 2008年第3期21卷 241-246页

作者： Sung-Gaun kim Ilhyun kim Amkee kim Seung-joon kim Junhong Park Division of Mechanical and Automotive Engineering Kongju National University 275 Budae-dongCheonan Chungnam 330-717 Korea Department of Mechanical Engineering Hanyang University Seongdong-Gu Seoul 133-791 Korea

The permanent residual strain in aluminum （Al） alloy foams induced by compressive fatigue gradually increases with the increasing number of loading cycles. Consequently, the progressive shortening of Al-alloy foam degrades the dynamic material performance by the failure and ratcheting of multi-cells in the foam. In this paper, the dynamic properties of Al-alloy foams damaged by compressive fatigue were studied. The beam specimens with various residual strains were made by cyclic compression-compression stress. The dynamic bending modulus and loss factor were evaluated by using a beam transfer function method. As a result, the dynamic bending stiffness of Al-alloy foam turned out to be decreased due to damage while the loss factor was improved because of the increasing energy dissipation of such factors as cracked cell walls formed during the shortening process of the foam. The loss factor shows a manifest dependence on the fatigue residual strain.

关键词： Aluminum foam fatigue dynamic stiffness loss factor

X region mutations of hepatitis B virus related to clinical severity

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World Journal of Gastroenterology 2016年第24期22卷 5467-5478页

作者： Hong kim Seoung-Ae Lee Bum-joon kim Department of Biomedical Sciences Microbiology and Immunology Liver Research Institute and Cancer Research Institute College of Medicine Seoul National University

Chronic hepatitis B virus (HBV) infection remains a major health problem, with more than 240 million people chronically infected worldwide and potentially 650000 deaths per year due to advanced liver diseases including liver cirrhosis and hepatocellular carcinoma (HCC). HBV-X protein (HBx) contributes to the biology and pathogenesis of HBV via stimulating virus replication or altering host gene expression related to HCC. The HBV X region contains only 465 bp encoding the 16.5 kDa HBx protein, which also contains several critical cis-elements such as enhancer II, the core promoter and the microRNA-binding region. Thus, mutations in this region may affect not only the HBx open reading frame but also the overlapped cis-elements. Recently, several types of HBx mutations significantly associated with clinical severity have been described, although the functional mechanism in most of these cases remains unsolved. This review article will mainly focus on the HBx mutations proven to be significantly related to clinical severity via epidemiological studies.

关键词： Hepatitis B virus infection Hepatitis B virus-X protein mutation Hepatocellular carcinoma Clinical severity