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Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief

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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

Early extrahepatic recurrence as a pivotal factor for survival after hepatocellular carcinoma resection:A 15-year observational study

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World Journal of Gastroenterology 2022年第36期28卷 5351-5363页

作者： Jae Hyun Yoon sung Kyu Choi sung Bum Cho Hee joon kim Yang Seok Ko Chung Hwan Jun Department of Gastroenterology and Hepatology Chonnam National University Hospital and College of MedicineGwangju 61469South Korea Department of Gastroenterology and Hepatology Hwasun Chonnam National University Hospital and College of MedicineHwasun 58128South Korea Department of Surgery Chonnam National University Hospital and College of MedicineGwangju 61469South Korea Department of Surgery Hwasun Chonnam National University Hospital and College of MedicineHwasun 58128South Korea Department of Internal Medicine Mokpo Hankook HospitalMokpo 58643South Korea

BACKGROUND Surgical resection is one of the most widely used modalities for the treatment of hepatocellular carcinoma(HCC).Early extrahepatic recurrence(EHR)of HCC after surgical resection is considered to be closely associated with poor ***,data regarding risk factors and survival outcomes of early EHR after surgical resection remain *** To investigate the clinical features and risk factors of early EHR and elucidate its association with survival *** From January 2004 to December 2019,we enrolled treatment-naïve patients who were≥18 years and underwent surgical resection for HCC in two tertiary academic *** excluding patients with tumor types other than HCC and/or ineligible data,this retrospective study finally included 779 *** resection of HCC was performed according to the physicians’decisions and the EHR was diagnosed based on contrast-enhanced computed tomography or magnetic resonance imaging,and pathologic confirmation was performed in selected *** Cox regression analysis was performed to identify the variables associated with *** Early EHR within 2 years after surgery was diagnosed in 9.5%of patients during a median followup period of 4.4 *** recurrence-free survival period was 5.2 mo,and the median time to EHR was 8.8 mo in patients with early *** 52.7%of patients with early EHR,EHR occurred as the first recurrence of HCC after surgical *** multivariate analysis,serum albumin100 U/L,surgical margin involvement,venous and/or lymphatic involvement,satellite nodules,tumor necrosis detected by pathology,tumor size≥7 cm,and macrovascular invasion were determined as risk factors associated with early *** sub-categorizing the patients according to the number of risk factors,the rates of both EHR and survival showed a significant correlation with the risk of early ***,multivariate analysis revealed that early E

关键词： Early extrahepatic recurrence Hepatocellular carcinoma Prognosis Surgery Survival

Primary duodenal dedifferentiated liposarcoma:A case report and literature review

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World Journal of Clinical Cases 2022年第6期10卷 2007-2014页

作者： Nah Ihm kim Ji Shin Lee Chan Choi Jong Hee Nam Yoo Duk Choi Hee joon kim sung Sun kim Department of Pathology Chonnam National University HospitalGwangju 61469South Korea Department of Pathology Chonnam National University Hwasun HospitalHwasun 58128South Korea Department of Surgery Chonnam National University HospitalGwangju 61469South Korea

BACKGROUND Dedifferentiated liposarcoma(DDLPS)is an extremely rare neoplasm that exhibits various *** tumor is characterized by immunoreactivity to MDM2 and CDK4 and can be confirmed by detecting MDM2 amplification via fluorescence in situ hybridization(FISH).Herein,we report an unusual case of DDLPS arising from the *** SUMMARY A 64-year-old man presented with repeated abdominal pain and weight *** studies revealed a mass of the duodenum involving the *** patient was treated with pylorus-preserving ***,the tumor showed a high-grade *** demonstrated that the tumor cells were positive for MDM2 and CDK4 ***2 amplification was detected via FISH,leading to the final diagnosis of *** surgery,the patient was treated in the intensive care unit due to peritonitis,and died 60 d after *** To the best of the authors’knowledge,this is the first case of primary duodenal DDLPS in Korea and the third case in the English-language *** must be taken not to misdiagnose DDLPS as another high-grade *** should be in the differential diagnosis list.

关键词： Liposarcoma Primary Small bowel Duodenum Immunohistochemistry Case report

Byte Frequency Based Indicators for Crypto-Ransomware Detection from Empirical Analysis

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Journal of Computer Science & Technology 2022年第2期37卷 423-442页

作者： Geun Yong kim joon-Young Paik Yeongcheol kim Eun-Sun Cho Department of Computer Science and Engineering Chungnam National UniversityDaejeon 34134South Korea School of Computer Science and Technology Tiangong UniversityTianjin 300387China

File entropy is one of the major indicators of crypto-ransomware because the encryption by ransomware increases the randomness of file ***,entropy-based ransomware detection has certain limitations;for example,when distinguishing ransomware-encrypted files from normal files with inherently high-level entropy,misclassification is very *** addition,the entropy evaluation cost for an entire file renders entropy-based detection impractical for large *** this paper,we propose two indicators based on byte frequency for use in ransomware detection;these are termed EntropySA and DistSA,and both consider the interesting characteristics of certain file subareas termed“sample areas”(SAs).For an encrypted file,both the sampled area and the whole file exhibit high-level randomness,but for a plain file,the sampled area embeds informative structures such as a file header and thus exhibits relatively low-level randomness even though the entire file exhibits high-level *** and DistSA use“byte frequency”and a variation of byte frequency,respectively,derived from sampled *** indicators cause less overhead than other entropy-based detection methods,as experimentally proven using realistic ransomware *** evaluate the effectiveness and feasibility of our indicators,we also employ three expensive but elaborate classification models(neural network,support vector machine and threshold-based approaches).Using these models,our experimental indicators yielded an average Fl-measure of 0.994 and an average detection rate of 99.46%for file encryption attacks by realistic ransomware samples.

关键词： computer security cryptography machine learning ransomware

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

Fe_(3)GeTe_(2):a site-differentiated Hund metal

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npj Computational Materials 2022年第1期8卷 2355-2360页

作者： Taek Jung kim Siheon Ryee Myung joon Han Department of Physics KAISTDaejeon34141Republic of Korea I.Institute of Theoretical Physics University of HamburgNotkestrasse 9-11Hamburg22607Germany

Magnetism in two-dimensional(2D)van der Waals(vdW)materials has lately attracted considerable attention from the point of view of both fundamental science and device ***,establishing a detailed and solid understanding of their magnetism is the key first step toward various *** Fe_(3)GeTe_(2)is a representative ferromagnetic(FM)metal in this family,many aspects of its magnetic and electronic behaviors still remain ***,we report our new finding that Fe_(3)GeTe_(2)is a special type of correlated metal known as“Hund metal”.Furthermore,we demonstrate that Hund metallicity in this material is quite unique by exhibiting remarkable site dependence of Hund correlation strength,hereby dubbed“site-differentiated Hund metal”.Within this new picture,many of the previous experiments can be clearly understood,including the ones that were seemingly contradictory to one another.

关键词： strength establishing metallic

Dynamic observation of dendrite growth on lithium metal anode during battery charging/discharging cycles

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npj Computational Materials 2022年第1期8卷 960-972页

作者： Hae Gon Lee Se Young kim joon Sang Lee Next Generation Battery Research Center Korea Electrotechnology Research Institute(KERI)12Jeongiui-gilSeongsan-guChangwon-siGyeongsangnam-do51543Republic of Korea Department of Mechanical Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Republic of Korea

Lithium metal is considered one of the most promising anode materials for application in next-generation ***,despite decades of research,practical application of lithium metal batteries has not yet been achieved because the fundamental interfacial mechanism of lithium dendrite growth is not yet fully *** this study,a series of reactive molecular dynamics (MD) simulations was performed to investigate the electrochemical dynamic reactions at the electrode/electrolyte *** allows quantitative characterization of morphological phenomena and real-time interfacial visualization of the dynamic growth of dead lithium and dendrites during repeated *** computational protocol was utilized to investigate the dendrite mitigation mechanism when an electrolyte additive (hydrogen fluoride) is dissolved in an organic ethylene carbonate (EC) electrolyte *** was confirmed that beneficial decomposition reactions between electrolyte components form a protective film on the anode surface,suppressing large interphase volume changes and unnecessary degradation reactions.

关键词： battery lithium electrolyte