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Deformation prediction of porcelain-enameled steels with strain history by press forming and high-temperature behavior of coating layer

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中国有色金属学会会刊：英文版 2012年第S3期22卷 838-844页

作者： Young-Ki SON Chan-Joo LEE Jung-min LEE byung-min kim School of Mechanical Engineering Pusan National University Dongnam Regional Division Korea Institute of Industrial Technology

Porcelain enamel coatings were widely applied for the protection of steel products because they offered high corrosion protection,resistance to heat and abrasion,high hardness,hygiene and ease of *** typical process to produce enameled steels is roughly divided into two stages:the first stage consists of a forming process to give the desired shape to a steel substrate,and the second stage consists of a firing process to bond enamel frits on the *** firing process requires a high temperature above 800 °C,which may lead to austenitic transformation and severe thermal deformation of the steel *** aim of this study is to develop a finite element analysis (FE analysis) technique to predict the mechanical and thermal deformations of the enameled steels during forming and any further enameling process,including *** FE analysis involves analyzing the strain history of the steel substrate,which comprises the stress and thickness distributions of the substrate and its deformed shape,and the high-temperature behavior of the enamel coating *** validity of the FE analysis is verified through the U-bending test and firing test with various numbers and positions of enamel coating layers on the *** results reveal that the FE analysis results agree well with the experimental results with 8% error.

关键词： porcelain enamel firing process finite element analysis enameled steel thermal deformation

Effects of elastic-plastic properties of materials on residual indentation impressions in nano-indentation using sharp indenter

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中国有色金属学会会刊：英文版 2012年第S3期22卷 585-595页

作者： Jung-min LEE Chan-Joo LEE Kyung-Hun LEE byung-min kim Dongnam Regional Division Korea Institute of Industrial Technology Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the ***,this indirect measurement occasionally leads to inaccurate properties of the indented *** objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation *** relations between the residual indentation profile and n value of the indented material were identified by dimensional ***,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and *** parameters of hrp/hm,herp/hm,Rr/hm and HO&P/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after *** were subsequently characterized as dimensionless functions using n and E/σr ***,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.

关键词： nano-indentation pile-up sink-in strain hardening exponent FE simulation

FEA technique of hot plate forming process using cell-typed die with cooling device

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中国有色金属学会会刊：英文版 2012年第S3期22卷 831-837页

作者： Jung-min LEE In-Kyu LEE Kyung-Hun LEE Dae-Soon kim byung-min kim Dongnam Regional Division Korea Institute of Industrial Technology School of Mechanical Engineering Pusan National University Industrial Technology Division Hyundai Heavy Industries

Hot plate forming using a cell-typed die is a process for forming a large thick plate with a spherical shape for the manufacture of a large spherical LNG ***-typed upper and lower dies made of a framework of steel plates fitted to make a grid pattern are used in this process,and an air-cooling device is separately installed inside the lower die.A finite element analysis (FEA) technique was developed,which included hot forming,air flow,cooling and thermal deformation analysis for the hot plate forming process using the cell-typed ***,the convective and interface heat transfer coefficients were used to reproduce analytically the effects of the cooling device in the hot plate forming analysis.A small-scale model test of the process was conducted to verify the FEA *** analysis results show that the curvature of the final plate agrees well with that of the designed experiment within a maximum relative error of 0.03% at the corner of the plate.

关键词： cell-typed die hot plate forming spherical LNG tank heat transfer coefficient

Retinal artery/arteriole occlusion risks after endovascular treatment for unruptured intracranial aneurysm

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Stroke & Vascular Neurology 2024年第3期9卷 295-305,I0251-I0263页

作者： Hae Rang kim min Jeoung kim Sunyeup kim Myung Soo Chang Dong Joon kim byung Moon kim Keun Young Park Yong Bae kim Christopher Seungkyu Lee Suk Ho Byeon Sung Soo kim Seung Won Lee Yong Joon kim Department of Ophthalmology CHA Bundang Medical CenterCHA University College of MedicineSeongnamKorea(the Republic of) Department of Neurosurgery Severance Stroke CenterSeverance HospitalYonsei University College of MedicineSeoulKorea(the Republic of) Department of Neurosurgery Uijeongbu St.Mary’s HospitalThe Catholic University of Korea College of MedicineUijeongbuKorea(the Republic of) Department of Medical AI Sungkyunkwan University School of MedicineSuwonKorea(the Republic of) Department of Ophthalmology Institute of Vision ResearchYonsei University College of MedicineSeoulKorea(the Republic of) Department of Radiology Severance Stroke CenterSeverance HospitalYonsei University College of MedicineSeoulKorea(the Republic of) Department of Precision Medicine Sungkyunkwan University School of MedicineSuwonKorea(the Republic of)

Background To evaluate the association between retinal artery/arteriole occlusion(RAO)and unruptured intracranial aneurysm(UIA).Methods Incident UIA patients from a nationwide cohort(n=253240)were categorised into three groups based on subsequent treatment:observation(n=208993),microsurgical clipping(n=14168)and endovascular treatment(EVT)groups(n=30079).The incidence and the incident time of RAO were *** of RAO and associated risk factors were ***,a hospital cohort comprising 2569 consecutive UIA patients treated at a tertiary hospital was analysed with detailed clinical information of *** In the nationwide cohort analysis,the incidence of RAO was significantly higher in EVT group than in observation and clipping groups,especially within 60 days(early RAO(within 60 days):HR=4.00,95%CI:2.44 to 6.56);delayed RAO(after 60 days:HR=1.74,95%CI:1.13 to 2.68).Multivariable analysis showed that the presence of chronic kidney disease(p=0.009)and use of a balloon microcatheter during the procedure(p=0.013)were associated with a higher risk of *** hospital cohort analysis,11(0.8%)cases of RAO occurred after EVT,whereas none occurred after microsurgical clipping(pming EVT for UIA may increase the risk of subsequent *** should be taken when treating paraclinoid aneurysms with balloon microcatheters.

关键词： treatment nationwide balloon

Tracking of horizontal alignment of the long and large diameter uncharged hole in NATM tunnel

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Underground Space 2024年第3期16卷 18-28页

作者： min-Seong kim Sean Seungwon Lee Department of Energy and Resources Engineering Chonnam National UniversityGwangju 61186Republic of Korea Department of Earth Resources and Environmental Engineering Hanyang UniversitySeoul 04763Republic of Korea

The long and large diameter uncharged hole boring(LLB)method is a cut blasting method that minimizes blast-induced vibrations by creating long and large diameter uncharged holes at the excavation face of tunnels prior to tunnel *** in this method typically uses a 50 m long with a 382 mm diameter hammer bit in the horizontal direction at the tunnel ***,the significant weight and uni-directional rotation of the rod head,as well as variables such as geological characteristics,machine conditions,and inexperienced operators result in significant deviation from the target borehole alignment that hinders the vibration-dampening effect of the uncharged ***,since there is no method to verify the alignment of the boreholes until main tunnel construction,borehole misalignment is often not discovered until weeks after construction,which requires tunnel construction to cease until the equipment can be remobilized and an additional borehole be created,causing significant delays and increased costs for the entire tunnel *** this study,the borehole alignment tracking and ground exploration system(BGS)is developed to predict and monitor the quality and alignment of boreholes for cut blasting methods such as the LLB methods immediately after *** BGS was subsequently tested at a subway construction site to evaluate its performance in the *** measurements yielded by the BGS were compared with manually measured boring positions at every 5 m along the *** the BGS showed a maximum deviation of approximately 12%at a local point where the hole surface was relatively rough,the accuracy for the final boring position was approximately 97%,demonstrating excellent precision of the alignment tracking *** BGS demonstrates excellent performance in predicting ground conditions and the boring quality of a cut hole immediately after drilling,and shows promise in various other applications for monitoring borehole alignment.

关键词： Tunnel blasting LLB method Drilling deviation Vertical sagging Horizontal alignment tracking BGS

Anomaly Detection in Imbalanced Encrypted Traffic with Few Packet Metadata-Based Feature Extraction

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 585-607页

作者： min-Gyu kim Hwankuk kim Department of Financial Information Security Kookmin UniversitySeoul02707Republic of Korea Department of Information Security Cryptography Mathematics Kookmin UniversitySeoul02707Republic of Korea

In the IoT(Internet of Things)domain,the increased use of encryption protocols such as SSL/TLS,VPN(Virtual Private Network),and Tor has led to a rise in attacks leveraging encrypted *** research on anomaly detection using AI(Artificial Intelligence)is actively progressing,the encrypted nature of the data poses challenges for labeling,resulting in data imbalance and biased feature extraction toward specific *** study proposes a reconstruction error-based anomaly detection method using an autoencoder(AE)that utilizes packet metadata excluding specific node *** proposed method omits biased packet metadata such as IP and Port and trains the detection model using only normal data,leveraging a small amount of packet *** makes it well-suited for direct application in IoT environments due to its low resource *** experiments comparing feature extraction methods for AE-based anomaly detection,we found that using flowbased features significantly improves accuracy,precision,F1 score,and AUC(Area Under the Receiver Operating Characteristic Curve)score compared to packet-based ***,for flow-based features,the proposed method showed a 30.17%increase in F1 score and improved false positive rates compared to Isolation Forest and ***,the proposedmethod demonstrated a 32.43%higherAUCwhen using packet features and a 111.39%higher AUC when using flow features,compared to previously proposed oversampling *** study highlights the impact of feature extraction methods on attack detection in imbalanced,encrypted traffic environments and emphasizes that the one-class method using AE is more effective for attack detection and reducing false positives compared to traditional oversampling methods.

关键词： One-class anomaly detection feature extraction auto-encoder encrypted traffic CICIoT2023

Weighted Forwarding in Graph Convolution Networks for Recommendation Information Systems

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Computers, Materials & Continua 2024年第2期78卷 1897-1914页

作者： Sang-min Lee Namgi kim Department of Computer Science Kyonggi UniversitySuwonKorea

Recommendation Information Systems(RIS)are pivotal in helping users in swiftly locating desired content from the vast amount of information available on the *** Convolution Network(GCN)algorithms have been employed to implement the RIS ***,the GCN algorithm faces limitations in terms of performance enhancement owing to the due to the embedding value-vanishing problem that occurs during the learning *** address this issue,we propose a Weighted Forwarding method using the GCN(WF-GCN)*** proposed method involves multiplying the embedding results with different weights for each hop layer during graph *** applying the WF-GCN algorithm,which adjusts weights for each hop layer before forwarding to the next,nodes with many neighbors achieve higher embedding *** approach facilitates the learning of more hop layers within the GCN *** efficacy of the WF-GCN was demonstrated through its application to various *** the MovieLens dataset,the implementation of WF-GCN in LightGCN resulted in significant performance improvements,with recall and NDCG increasing by up to+163.64%and+132.04%,***,in the *** dataset,LightGCN using WF-GCN enhanced with WF-GCN showed substantial improvements,with the recall and NDCG metrics rising by up to+174.40%and+169.95%,***,the application of WF-GCN to Self-supervised Graph Learning(SGL)and Simple Graph Contrastive Learning(SimGCL)also demonstrated notable enhancements in both recall and NDCG across these datasets.

关键词： Deep learning graph neural network graph convolution network graph convolution network model learning method recommender information systems

Intelligent structured nanocomposite adhesive for bioelectronics and soft robots

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Nano Research 2024年第2期17卷 534-549页

作者： Yeon Soo Lee min-Seok kim Da Wan kim Changhyun Pang School of Chemical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Mechanical Metrology Group Korea Research Institute of Standards and ScienceDaejeon 34113Republic of Korea Department of Electronic Engineering Korea National University of TransportationChungbuk 27469Republic of Korea Samsung Advanced Institute for Health Sciences and Technology Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea

The remarkable functionality of biological systems in detecting and adapting to various environmental conditions has inspired the design of the latest electronics and robots with advanced *** review focuses on intelligent bio-inspired strategies for developing soft bioelectronics and robotics that can accommodate nanocomposite adhesives and integrate them into biological *** underlying principles of the material and structural design of nanocomposite adhesives were investigated for practical applications with excellent functionalities,such as soft skin-attachable health care sensors,highly stretchable adhesive electrodes,switchable adhesion,and untethered soft *** addition,we have discussed recent progress in the development of effective fabrication methods for micro/nanostructures for integration into devices,presenting the current challenges and prospects.

关键词： biomimetics bio-adhesive switchable adhesion bioelectronics nanocomposite soft robotics

Soleus arthrogenic muscle inhibition following acute lateral ankle sprain correlates with symptoms and ankle disability but not with postural control

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Journal of Sport and Health Science 2024年第4期13卷 559-568,F0003页

作者： Kyung-min kim Joo-Sung kim Alan R.Needle Department of Sport Science Sungkyunkwan UniversitySuwon-si 16419Republic of Korea Department of Health and Human Performance Texas State UniversitySan MarcosTX 78666USA Department of Public Health&Exercise Science Appalachian State UniversityBooneNC 28608USA Department of Rehabilitation Science Appalachian State UniversityBooneNC 28608USA

Background:Acute lateral ankle sprains(ALAS)are associated with long-term impairments and instability tied to altered neural *** muscle inhibition(AMI)has been observed in this population;however,relationships with injury-related impairments are unclear,potentially due to the resting,prone position in which AMI is typically *** AMI during bipedal stance may provide a better understanding of this ***:AMI was assessed in 38 young adults(19 ALAS within 72 h of injury:10 males,21.4±2.7 years;19 healthy controls:10 males,21.9±2.2 years;mean±SD)using the Hoffmann reflex(H-reflex)during bipedal *** stimulation was administered to identify the _(max)imal H-reflex(H_(max))and _(max)imal motor response(M_(max))from the soleus,fibularis longus,and tibialis anterior *** primary outcome measure was the H_(max)/M_(max) *** outcomes included acute symptoms(pain and swelling),postural control during bipedal stance,and self-reported ***:No significant group-by-limb interactions were observed for any ***,a significant group main effect was observed in the soleus muscle(F(1,35)=6.82,p=0.013),indicating significantly lower H_(max)/M_(max) ratios following ALAS(0.38±0.20)compared to healthy controls(0.53±0.16).Furthermore,lower H_(max)/M_(max) ratios in the soleus significantly correlated with acute symptoms and self-reported function but not with postural ***:This study supports previous evidence of AMI in patients with ALAS,providing insight into neurophysiologic impacts of musculoskeletal *** results suggest that assessing AMI in a standing position following acute injury may provide valuable insight into how AMI develops and guide potential therapeutic options to curb and offset the formation of joint instability.

关键词： Acute injuries Balance Hoffmann reflex Neural excitability Patient-reported outcomes