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Microstructural characteristics and low-cycle fatigue properties of AZ91 and AZ91-Ca-Y alloys extruded at different temperatures

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Journal of Magnesium and Alloys 2023年第3期11卷 892-902页

作者： Ye Jin Kim Young min Kim Jun Ho Bae Soo-Hyun Joo sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Dankook UniversityCheonan 31116Republic of Korea

The commercial AZ91 alloy and nonflammable SEN9(AZ91-0.3Ca-0.2Y,wt%)alloy are extruded at 300°C and 400°*** microstructure,tensile and compressive properties,and low-cycle fatigue(LCF)properties are investigated,with particular focus on the influence of the extrusion *** the AZ91 and SEN9 materials extruded at 300°C(300-materials),numerous fine Mg_(17)Al_(12)particles are inhomogeneously distributed owing to localized dynamic precipitation during extrusion,unlike those extruded at 400°C(400-materials).These fine particles suppress the coarsening of recrystallized grains,decreasing the average grain size of *** the four extruded materials have considerably different microstructures,the difference in their tensile yield strengths is insignificant because strong grain-boundary hardening and precipitation hardening effects in 300-materials are offset almost completely by a strong texture hardening effect in ***,owing to their finer grains and weaker texture,300-materials have higher compressive yield strengths *** the LCF tests,{10-12}twinning is activated at lower stresses in 400-materials than in *** the fatigue damage accumulated per cycle is smaller in 400-materials,they have longer fatigue lives than those of 300-materials.A fatigue life prediction model for the investigated materials is established on the basis of the relationship between the total strain energy density(ΔW_(t))and the number of cycles to fatigue failure(N_(f)),and it is expressed through a simple equation(ΔW_(t)=10·N_(f)-0.59).This model enables fatigue life prediction of both the investigated alloys regardless of the extrusion temperature and strain amplitude.

关键词： AZ91-Ca-Y Extrusion temperature Microstructure Low-cycle fatigue Fatigue life prediction model

Scalp electroacupuncture at the Baihui acupoint (DU 20) improves functional recovery in rats with cerebral ischemia Association with increased expression of vascular endothelial growth factors

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Neural Regeneration Research 2011年第36期6卷 2822-2828页

作者： min-Wook Kim You Chul chung Hee Chan Jung Moon-Seo Park Young-min Han Yong-An chung Lee-So Maeng Sang-In Park Jiyeon Lim Seung Chan Kim Woo-Seok Im Jin Young chung minky Kim Manho Kim Institute of Catholic Integrative Medicine (ICIM) Incheon St. Mary’s Hospital Catholic University of Korea Incheon Korea Department of Rehabilitation Medicine Catholic University of Korea Seoul Korea Department of Neurology Seoul National University Hospital SNUMRC Seoul Korea Department of Biotechnology Yonsei University Seoul Korea Department of Neurology Seoul Medical Center Seoul Korea

In this study, we induced cerebral infarction in rats by occluding the right middle cerebral artery, and tested the effects of electroacupuncture at the Baihui acupoint （DU 20）. Motor and sensory function was tested using Garcia’s scale and motor weakness grading, and the expression of vascular endothelial growth factor in the brain was quantified using immunoblotting and immunohistochemistry. We found that scalp electroacupuncture at DU 20 significantly improved motor performance and sensory function in rats with stroke, and this was accompanied by an increased expression of vascular endothelial growth factor in the ischemic brain tissue and peri-ischemic area. In addition, Pearson correlation analysis showed that the improvements in functional recovery were correlated with the increased expression of vascular endothelial growth factor.

关键词： electroacupuncture cerebrovascular disorder vascular endothelial growth factor Baihui acupoint functional improvement

Denoising method of X-ray phase contrast DR image for TRISO-coated fuel particles

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Particuology 2013年第6期11卷 695-702页

作者： min Yang Jianhai Zhang Fanyong Meng sung-Jin Song Xingdong Li Wenli Liu Dongbo Wei School of Mechanical Engineering and Automation Beijing University of Aeronautics School of Mechanical Engineering Sungkyunkwan University State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences National Institute of Metrology

TRISO （tristructural-isotropic） fuel is a type of micro fuel particles used in high-temperature gas-cooled reactors （HTGRs）. Among the quality evaluation methods for such particles, inqine phase contrast imaging technique （PCI） is more feasible for nondestructive measurement. Due to imaging hardware limitations, high noise level is a distinct feature of PCI images, and as a result, the dimensional measurement accuracy of TRISO-coated fuel particles decreases. Therefore, we propose an improved denoising hybrid model named as NL P-M model which introduces non-local theory and retains the merits of the Perona-Malik （P-M） model. The improved model is applied to numerical simulation and practical PCI images. Quanti- tative analysis proves that this new anisotropic diffusion model can preserve edge or texture information effectively, while ruling out noise and distinctly decreasing staircasing artifacts. Especially during the process of coating layer thickness measurement, the NL P-M model makes it easy to obtain continuous contours without noisy points or fake contour segments, thus enhancing the measurement accuracy. To address calculation complexity, a graphic processing unit （GPU） is adopted to realize the acceleration of the NL P-M denoising.

关键词： TRISO-coated fuel particle X-ray phase contrast imaging Image denoising Partial differential equation Non-local means

Application of response surface method for optimal transfer conditions of multi-layer ceramic capacitor alignment system

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Journal of Central South University 2011年第3期18卷 726-730页

作者： PARK Su-seong KIM Jae-min chung Won-jee SHIN O-chul School of Mechatronics Changwon National University

The multi-layer ceramic capacitor (MLCC) alignment system aims at the inter-process automation between the first and the second plastic *** a result of testing performance verification of MLCC alignment system,the average alignment rates are 95% for 3216 chip,88.5% for 2012 chip and 90.8% for 3818 *** MLCC alignment system can be accepted for practical use because the average manual alignment is just 80%.In other words,the developed MLCC alignment system has been upgraded to a great extent,compared with manual *** on the successfully developed MLCC alignment system,the optimal transfer conditions have been explored by using *** simulations using ADAMS has been performed according to the cube model of *** using miniTAB,the model of response surface has been established based on the simulation *** optimal conditions resulted from the response optimization tool of miniTAB has been verified by being assigned to the prototype of MLCC alignment system.

关键词： multi-layer ceramic capacitor (MLCC) alignment system response surface method (RSM) miniTAB ADAMS

Virtual Reality-Based Random Dot Kinematogram

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Computers, Materials & Continua 2021年第9期68卷 4205-4213页

作者： Jun Ma Hyo-Jung Kim Ji-Soo Kim Eek-sung Lee min Hong Department of Software Convergence Soonchunhyang UniversityAsan31538Korea Research Administration Team Seoul National University Bundang HospitalSeongnam13620Korea Dizziness Center Clinical Neuroscience CenterDepartment of NeurologySeoul National University Bundang HospitalSeongnam13620Korea Department of Neurology Seoul National University College of MedicineSeoul03080Korea Department of Neurology College of MedicineSoonchunhyang UniversityBucheon14584Korea Department of Computer Software Engineering Soonchunhyang UniversityAsan31538Korea

This research implements a random dot kinematogram(RDK)using virtual reality(VR)and analyzes the results based on normal *** motion perception is one of visual functions localized to a specific cortical area,the human motion perception area(human analogue for the middle temporal/middle superior temporal area)located in the parieto–occipito–temporal junction of the human *** RDK measures visual motion perception *** stimuli in conventional RDK methods are presented using a monitor screen,so these devices require a spacious dark room for installation and ***,VR technology has been implemented in different medical *** test method proposed in this study include a VR-based RDK that can independently measure human motion perception abilities without any spatial constraints via a VR head-mounted ***,the VR-based RDK was implemented,and the visual perception abilities of the normal subjects were measured based on varying *** both screen-and VR-based RDK tests,the easier the stimulus is,the higher the correct answer rate and the shorter the reaction *** significant differences in coherence thresholds were observed between the two test *** VRbased RDK proposed in this study can be used as a diagnosis tool for visual motion perception and neurodegenerative disorders affecting the posterior region of the brain.

关键词： Random dot kinematogram virtual reality visual psychophysics diagnostic device

Unexpected Pulmonary Events during Endotracheal Intubation in a Pediatric Patient

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Chinese Medical Journal 2017年第18期130卷 2263-2264页

作者： Hue Jung Park Haewon chung min Soo Lee Hyun Jung Koh Department of Anesthesiology and Pain Medicine Seoul St. Mary's Hospital College of Medicine The Catholic University of Korea Seoul 06591Republic of Korea

Nearly 21% of pediatric surgical operations are accompanied by adverse events,12.8% of which are respiratory complications including bronchospasm （1.2%） and pulmonary edema （11%）. Among them,aspiration pneumonia and negative-pressure pulmonary edema are rare pulmonary complications in ***,they are difficult to predict and can be fatal if not appropriately treated;careful monitoring is *** present a case of pulmonary complication secondary to aggravation of bronchial spasm during intubation of a pediatric patient.

关键词： Aspiration Bronchial Spasm Intubation Pneumonia

Real-time multiaxial strain mapping using computer vision integrated optical sensors

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npj Flexible Electronics 2023年第1期7卷 253-264页

作者： sunguk Hong Vega Pradana Rachim Jin-Hyeok Baek sung-min Park Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673South Korea Department of Convergence IT Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673South Korea School of Interdisciplinary Bioscience and Bioengineering Pohang University of Science and Technology(POSTECH)Pohang 37673South Korea Department of Electrical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673South Korea Institute of Convergence Science Yonsei UniversitySeoul 120-749South Korea

Soft strain sensors pose great potential for emerging human–machine ***,their real-world applications have been limited due to challenges such as low reproducibility,susceptibility to environmental noise,and short lifetimes,which are attributed to nanotechnologies,including microfabrication *** this study,we present a computer vision-based optical strain(CVOS)sensor system that integrates computer vision with streamlined microfabrication techniques to overcome these challenges and facilitate real-time multiaxial strain *** proposed CVOS sensor consists of an easily fabricated soft silicone substrate with micro-markers and a tiny camera for highly sensitive marker ***-time multiaxial strain mapping allows for measuring and distinguishing complex multi-directional strain patterns,providing the proposed CVOS sensor with higher *** results indicate that the proposed CVOS sensor is a promising approach for the development of highly sensitive and versatile human–machine interfaces that can operate long-term under real-world conditions.

关键词： computer mapping strain

Oncological safety of use of ultrasonic activated shears in gastric cancer surgery: Long-term results of randomized controlled trial

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Chinese Journal of Cancer Research 2018年第5期30卷 492-499页

作者： Su Mi Kim Jae-Moon Bae min-Gew Choi Jun Ho Lee Tae sung Sohn sung Kim Department of Surgery Samsung Medical Center Sungkyunkwan University School of Medicine

Objective： Ultrasonically activated shears （UAS） have been applied in open gastric surgeries with no or little evidence. It was previously reported about the surgical outcome and effectiveness of UAS based on a randomized controlled trial of 256 patients with gastric cancer. We aimed to clarify the long-term oncological safety of the use of UAS in the aspect of overall survival and ***： Gastric cancer patients who underwent gastrectomy with D2 lymph node dissection were enrolled and randomly assigned to either the conventional surgery group （n=125） or the UAS group （n=128）. Survival, recurrence and long-term postoperative complications were compared between the two groups. The median follow-up period was 56 ***： Gastric cancer-related death was higher in patients of the UAS group compared with the conventional group （P=0.019）. Overall survival rates stratified by stage were not significantly different between the two groups （P=0.170）. Disease-free survival rates stratified by stage and recurrence-free survival rates of gastric cancer were similar between the conventional group and the UAS group （P=0.313 and 0.199, respectively）. The postoperative complication rate was not significantly different between the groups （P=1.000）. Conclusions： It is suggested that the use of UAS in gastrectomy for gastric cancer showed oncologically acceptable safety compared with conventional electric instruments even in long-term period.

关键词： Stomach cancer gastrectomy ultrasonically activated shears (UAS) oncological safety

The hidden switches undertying RORα-mediated circuits that critically regulate uncontrolled cell proliferation

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Journal of Molecular Cell Biology 2014年第4期8卷 338-348页

作者： Dongkwan Shin Ik Soo Kim Ji min Lee sung-Young Shin Jong-Hoon Lee sung Hee Baek Kwang-Hyun Cho Department of Bio and Brain Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Republic of Korea Department of Biological Sciences Creative Research Initiative Center for Chromatin Dynamics Seoul National University Seou1151-742 Republic of Korea

Prostaglandin E2 （PGE2） is known to have a key role in the development of colorectal cancer, but previous experiments showed its contrasting （i.e. tumor-promoting or tu mor-suppressive） roles depending on experimental conditions. To elucidate the mechanisms underlying such contrasting roles of PG E2 in tumorigenesis, we investigated all the previous experiments and found a new signal transduction pathway mediated by retinoic acid receptor-related orphan receptor （ROR）α, in which PGE2/PKCα-dependent phosphorylation of RORα attenuates Wnt target gene expression in colon cancer ceils. From mathematical simulations combined with biochemical experimentation, we revealed that RORα induces a biphasic response of Wnt target genes to PGE2 stimulation through a regulatory switch formed by an incoherent feedforward loop, which provides a mechanistic explanation on the contrasting roles of PGE2 observed in previous experiments. More interestingly, we found that RORα constitutes another regulatory switch formed by coupled positive and negative feedback loops, which regulates the hysteretic response of Wnt signaling and eventually converts a proliferative cellular state into an anti-proliferative state in a very delicate way. Our results indicate that RORα is the key regulator at the center of these hidden switches that critically regulate cancer celt proliferation and thereby being a promising anti-cancer therapeutic target.

关键词： colorectal cancer Wnt signaling RORα mathematical modeling biphasic response hysteresis systems biology