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Optimal seismic retrofit model for steel moment resisting frames with brittle connections

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 835-847页

作者： Hyo seon Park se Woon choi Byung Kwan Oh Department of Architectural Engineering Yonsei University Center for Structural Health Care Technology in Building Yonsei University Department of Architecture Catholic University of Daegu Department of Civil and Environmental Engineering Princeton University

Based on performance-based seismic engineering, this paper proposes an optimal seismic retrofit model for steel moment resisting frames（SMRFs） to generate a retrofit scheme at minimal cost. To satisfy the acceptance criteria for the Basic Safety Objective（BSO） specified in FEMA 356, the minimum number of upgraded connections and their locations in an SMRF with brittle connections are determined by evolutionary computation. The performance of the proposed optimal retrofitting model is evaluated on the basis of the energy dissipation capacities, peak roof drift ratios, and maximum interstory drift ratios of structures before and after retrofitting. In addition, a retrofit efficiency index, which is defined as the ratio of the increment in seismic performance to the required retrofitting cost, is proposed to examine the efficiencies of the retrofit schemes derived from the model. The optimal seismic retrofit model is applied to the SAC benchmark examples for threestory and nine-story SMRFs with brittle connections. Using the retrofit efficiency index proposed in this study, the optimal retrofit schemes obtained from the model are found to be efficient for both examples in terms of energy dissipation capacity, roof drift ratio, and maximum inter-story drift ratio.

关键词： steel moment resisting frame performance-based seismic engineering optimal seismic retrofit evolutionarycomputation

Thermal deformation of aluminum alloy casting materials for tire mold by numerical analysis

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中国有色金属学会会刊：英文版 2012年第S3期22卷 859-863页

作者： Hee-Sung YOON Je-se choi Yool-Kwon OH Department of Advanced Parts and Materials Engineering Chosun University Department of Mechatronics Engineering Chosun University

Thermal deformation of aluminum alloy casting materials for manufacturing the tire mold was numerically *** AC7A and AC4C casting material was selected as casting material and the metal casting device was used in order to manufacture the mold product of automobile tire in the actual industrial *** temperature distribution and the cooling time of casting materials were numerically calculated by finite element analysis (FEA).Also,the thermal deformation such as displacement and stress distribution was calculated from the temperature *** thermal deformation was closely related to the temperature difference between the surface and inside of the *** numerical analysis results reveal that the thermal deformation of AC7A casting material is higher than that of AC4C casting ***,the thermal deformation results at the central part are larger than that on the side of casting because of the shrinkage caused by the cooling speed difference.

关键词： thermal deformation finite element analysis AC7A casting material AC4C casting material

Finite element analysis using elasto-visco-plastic self-consistent polycrystal model for E-form Mg sheet subjected to bending

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Journal of Magnesium and Alloys 2023年第4期11卷 1393-1407页

作者： Bohye Jeon Min-seong Kim Shi-hoon choi Youngung Jeong Department of Materials Convergence and System Engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea Center for Energy Materials Research Korea Institute of Science and TechnologySeoulRepublic of Korea Department of Advanced Components and Materials Engineering Sunchon National UniversitySuncheon-siJeollanam-doRepublic of Korea School of Materials Science and Engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea

The mechanical behavior of a magnesium alloy E-form under bending was investigated using the elasto-visco-plastic polycrystal model(ΔEVPSC) and its finite element(FE) implementation(ΔEVPSC-FE) developed in Jeong et al. and Jeong and Tomé. The crystallographic orientation distribution(COD) obtained from X-ray diffraction was used to represent the initial texture, and the Voce hardening parameters were calibrated by fitting the uniaxial tension and the compression flow stress curves. A quasi-static FE analysis of a miniaturized V-bending operation was conducted using the ΔEVPSC-FE model. The bending induced an inhomogeneous stress response along the through-thickness and the lateral directions, which was well captured by the model. Moreover, the predictive capability of the model was validated by comparing with various experimental results such as(1) force vs. displacement curves;(2) the through-thickness variations in the twin volume fraction;and(3) the changes in crystallographic texture as a function of displacement. Additional bending simulation was performed using an isotropic texture, the result of which suggests that the potential improvement in bendability of the magnesium alloy is attainable by weakening the initial texture. Moreover, the simulation results imply that the crystallographic texture, which may affect the twin activation across the thickness direction, plays a significant role in the shifting direction of the neutral layer.

关键词： FEM Texture V-bending Polycrystal Magnesium Elasto-visco-plasticity

Projections of ocean climate for northwestern Pacific Ocean

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Acta Oceanologica Sinica 2005年第1期24卷 134-145页

作者： choi Byung Ho KIM Dong hoon choi Young Jin YUK Jin Hee Department of Civil and Environmental Engineering Sungkyunkwan University Suwon KoreaAbiko Research Laboratory Central Research Institute of Electric Power Industry JapanResearch Institute of Applied Mechanics Kyushu University JapanDepartment of Civil and Environmental Engineering Sungkyunkwan University Suwon Korea

The long-term adjustment processes of atmosphere and ocean in response to gradually increased atmospheric CO2 concentration have been analyzed in 70 and 140 a integrations with NCAR fully-coupled climate system model (CSM). In these experiments the CO2 concentration has been increased to double and quadruples the initial concentration, respectively. After 70 a, at the time of CO2 doubling, the model predicts surface air temperature rises by 1.2 and 1.5 K for the globe and the northwestern Pacific Ocean, respectively. The behavior of the quadrupling run is similar: each global and regional mean surface air temperatures increase by 2.8 and 3.0 K at the time of CO2 quadrupling. From the experiments, surface air temperature changes in the northwestern Pacific Ocean will be more distinctive compared with the global average, mainly due to exceptionally large wanning and sea level change near the entrance of the Kuroshio extension.

关键词： Climate model simulation global warming northwestern Pacific Ocean

Endovascular treatment of traumatic renal artery pseudoaneurysm with a Stanford type A intramural haematoma:A case report

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World Journal of Clinical Cases 2022年第27期10卷 9760-9767页

作者： Yook Kim Jin Young Lee Jin Suk Lee Jin Bong Ye se Heon Kim Young hoon Sul Su Young Yoon Jung Hee choi Hanlim choi Department of Radiology Chungbuk National University HospitalCheongju-si 28644Chungcheongbuk-doSouth Korea Department of Trauma Surgery Chungbuk National University HospitalCheongju-si 28644Chungcheongbuk-doSouth Korea Department of Trauma Surgery College of MedicineChungbuk National UniversityCheongju-si 28644Chungcheongbuk-doSouth Korea Cardiovascular and Thoracic Surgery Chungbuk National University HospitalCheongju-si 28644Chungcheongbuk-doSouth Korea Anesthesiology and Pain Medicine Chungbuk National University HospitalCheongju-si 28644Chungcheongbuk-doSouth Korea Department of Surgery Chungbuk National University HospitalCheongju-si 28644Chungcheongbuk-doSouth Korea

BACKGROUND Aortic intramural hematoma(IMH) associated with aortic branch tear and intramurally located pseudoaneurysm after blunt trauma has not been ***,we report a case of progressive type A aortic IMH associated with a pseudoaneurysm arising from the injured proximal renal artery after blunt *** SUMMARY During logging operations,a 66-year-old man experienced blunt force trauma after being injured by a fallen *** arrived at our trauma center with a left flank pain *** tomography(CT) revealed a pseudoaneurysm arising from the proximal renal artery(localized within the aortic media) and Stanford type A IMH.A covered stent was deployed along the left main renal artery,bridging the pseudoaneurysm and covering the parent artery,successfully excluding the pseudoaneurysm as confirmed using ***,although the degree of the pseudoaneurysm decreased,follow-up CT revealed remnant pseudoaneurysm,likely caused by an ***,a covered stent was additionally installed through the previously deployed covered *** exclusion of the pseudoaneurysm was confirmed using final *** the 7-mo follow-up CT scan,the IMH and pseudoaneurysm completely disappeared with no evidence of stent-related *** Endovascular treatment such as stent-graft placement can be an effective and safe treatment for traumatic renal artery injury.

关键词： Aortic intramural hematoma Blunt trauma Intimomedial tear Renal arterial injury Stent-graft Case report

Fluid flow and heat transfer characteristics of spiral coiled tube: Effects of Reynolds number and curvature ratio

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Journal of Central South University 2012年第2期19卷 471-476页

作者： YOO Geun-jong choi hoon-ki DONG Wa-ryong School of Mechatronics Changwon National University

Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angle reached 12n. As the varying radius of curvature became a dominant flow parameter, three-dimensional flow analysis was performed to this flow together with different Reynolds numbers while constant wall heat flux condition was set in thermal field. From the analysis, centrifugal force due to curvature effect is found to have significant role in behavior of pressure drop and heat transfer. The centrifugal force enhances pressure drop and heat transfer to have generally higher values in the spiral coiled tube than those in the straight tube. Even then, friction factor and Nusselt number are found to follow the proportionality with square root of the Dean number. Individual effect of flow parameters of Reynolds number and curvature ratio was investigated and effect of Reynolds number is found to be stronger than that of curvature effect.

关键词： spiral coiled tube heat exchanger Reynolds number curvature ratio secondary flow friction factor Nusselt number

Characteristics of radiation and convection heat transfer in indirect near-infrared-ray heating chamber

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Journal of Central South University 2011年第3期18卷 731-738页

作者： choi hoon-ki YOO Geun-jong KIM Churl-hwan School of Mechatronics Changwon National University

Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.

关键词： near infrared ray indirect near infrared ray heater absorbing cylinder heat releasing fin radiation heat transfer convection heat transfer Reynolds number

Spectral Properties and Photochromic Characteristics of Spiropyran Dyes

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Chemical Research in Chinese Universities 2006年第4期22卷 505-509页

作者： SHEN Kai-hua HAN Jian-guo ZHANG Gang choi Dong-hoon The State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116012 P. R. China The Key Laboratory of Cellulose and Lignocellulosics Chemistry Guangzhou Institute of Chemistry Chinese Academy of Sciences Guangzhou 510650 P. R. China Polymer and Fiber Material Engineering Kyunghee University Kyong Kido 449-701 Korea

A bis-benzospiropyran（BBSP） and nitro-substituted indoline spirobenzopyrans（SBP） were prepared by following a simple procedure. The reaction mechanism of synthesizing bis-benzospiropyran is discussed. A comparative analysis of the spectral and photochromic properties between SBP and BBSP was carried out with the aid of a PMMA film. The results indicate that chemical structures and UV irradiation played an important role in the spectral and photochromic properties of SBP and BBSP, which would readily affect λmax of the colored forms and the reversibility. The IR spectra and ^1H NMR spectra of these compounds are used to interpret the photochromic phenomena under different UV irradiation and determine the configurations of SBP and BBSP.

关键词： Photochromism Spiropyran UV radiation Protonation

A Comprehensive Analysis of Datasets for Automotive Intrusion Detection Systems

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Computers, Materials & Continua 2023年第9期76卷 3413-3442页

作者： seyoung Lee Wonsuk choi InsupKim Ganggyu Lee Dong hoon Lee School of Cybersecurity Korea UniversitySeoul02841Korea Memory Division Samsung ElectronicsHwaseong18449Korea

Recently,automotive intrusion detection systems(IDSs)have emerged as promising defense approaches to counter attacks on in-vehicle networks(IVNs).However,the effectiveness of IDSs relies heavily on the quality of the datasets used for training and *** the availability of several datasets for automotive IDSs,there has been a lack of comprehensive analysis focusing on assessing these *** paper aims to address the need for dataset assessment in the context of automotive *** proposes qualitative and quantitative metrics that are independent of specific automotive IDSs,to evaluate the quality of *** metrics take into consideration various aspects such as dataset description,collection environment,and attack *** paper evaluates eight commonly used datasets for automotive IDSs using the proposed *** evaluation reveals biases in the datasets,particularly in terms of limited contexts and lack of ***,it highlights that the attacks in the datasets were mostly injected without considering normal behaviors,which poses challenges for training and evaluating machine learning-based *** paper emphasizes the importance of addressing the identified limitations in existing datasets to improve the performance and adaptability of automotive *** proposed metrics can serve as valuable guidelines for researchers and practitioners in selecting and constructing high-quality datasets for automotive security ***,this paper presents the requirements for high-quality datasets,including the need for representativeness,diversity,and balance.

关键词： Controller area network(CAN) intrusion detection system(IDS) automotive security machine learning(ML) dataset