http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Park, Siwook,Jung, Jinwook,Kim, Kyung Il,Kim, Hwangsun,Kim, Sung-Il,Oh, Kyu Hwan,Lee, Myoung-Gyu,Han, Heung Nam Elsevier 2019 International journal of mechanical sciences Vol.156 No.-
<P><B>Abstract</B></P> <P>A practical dual-scale finite element model is developed to enable the formability prediction in the hole expansion of a hyper-burring steel sheet. This numerical approach resorts to the isotropic macroscale hole expansion simulation for calculating the deformation histories near the hole edge, since they are known to be the potential fracture initiation site. The deformation histories are used as boundary conditions in the lower microscale model for calculating the local fracture of the steel sheet. The microscale simulation utilizes the dislocation density based constitutive model and a microstructure-based representative volume element (RVE), with realistic grain morphology taken from experimental microscopy. The fracture initiation at the hole edge region is evaluated from the microscale simulation using four frequently employed uncoupled ductile fracture models, which enable the definition of the critical fracture strain. The proposed dual-scale model can better predict the failure initiation and location near the hole edge when the modeling parameters are calibrated taking into account not only the deformation histories of the hole edge, but also the local stress triaxiality. Moreover, the proposed dual-scale model is applied to analyze the microstructure effect on the hole expansion ratio by providing the insights into the effect of grain size and grain boundary characteristics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A practical dual-scale finite element modeling is developed to simulate the hole expansion formability of a hyper-burring steel sheet. </LI> <LI> The microscale RVE model could take the pile up of dislocation density near the grain boundaries into account to estimate local strengthening at the grain boundary and inhomogeneous plastic deformation in the grain interior. </LI> <LI> The hole expansion simulations with different fracture models showed that HER could be better captured when the fracture criterion considered the stress triaxiality developed in the microstructure. </LI> <LI> From the microscopic simulation of hole expansion test, the higher hole expansion ratio could be predicted as the grain size increases and the degree of pile-up decreases. </LI> </UL> </P>
Electropulsing Treatment on Enhancement of Electrical Conductivity of Screen-Printed Ag Wire
Ju‑Won Park,Howook Choi,Hwangsun Kim,Simoon Sung,Hye‑Jin Jeong,Il Kim,Jaeseok Gong,Sung‑Tae Hong,Heung Nam Han 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5
The effect of high electric current density on the sintering of Ag wires manufactured by screen printing is evaluated throughelectrical resistivity analysis and microstructure observation. Different forms (continuous and pulsed) of electric currentwith different current densities are applied to the specimens. Conventional heat treatment is also performed as a controlgroup to examine the athermal effect of electropulsing treatment. Compared to the conventional heat treatment, the resistivityis reduced more under the electropulsing treatment with continuous current for the same temperature and treatment time.Also, the process time of electropulsing treatment can be reduced by applying a pulse form of high density current insteadof continuous current without losing the benefit of enhanced reduction of resistivity. The microstructural observationsobtained from high angle annular dark field scanning transmission electron microscope and a digital precession instrumentclearly show that necking connecting the crystals is formed more firmly under electric current. In addition, the temperaturechange of Ag wire and substrate is calculated according to the change of the resistivity when the electric current is appliedto confirm the reliability.
Hwang, Sun‐,Chul,Hwang, Dae Seok,Kim, Ho Yong,Kim, Min Ji,Kang, Young‐,Hoon,Byun, Sung‐,Hoon,Rho, Gyu‐,Jin,Lee, Hyeon‐,Jeong,Lee, Hee‐,Chun,Kim, Sang‐,Hyun,Ba Wiley Publishers 2019 JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A Vol.107 No.10
<P><B>ABSTRACT</B></P><P>Hypoxia and limited vascularization inhibit bone growth and recovery after surgical debridement to treat osteomyelitis. Similarly, despite significant efforts to create functional tissue‐engineered organs, clinical success is often hindered by insufficient oxygen diffusion and poor vascularization. To overcome these shortcomings, we previously used the oxygen carrier perfluorooctane (PFO) to develop PFO emulsion‐loaded hollow microparticles (PFO‐HPs). PFO‐HPs act as a local oxygen source that increase cell viability and maintains the osteogenic differentiation potency of human periosteum‐derived cells (<I>h</I>PDCs) under hypoxic conditions. In the present study, we used a miniature pig model of mandibular osteomyelitis to investigate bone regeneration using <I>h</I>PDCs seeded on PFO‐HPs (<I>h</I>PDCs/PFO‐HP) or <I>h</I>PDCs seeded on phosphate‐buffered saline (PBS)‐HPs (<I>h</I>PDCs/PBS‐HP). Osteomyelitis is characterized by a series of microbial invasion, vascular disruption, bony necrosis, and sequestrum formation due to impaired host defense response. Sequential plain radiography, computed tomography (CT), and 3D reconstructed CT images revealed new bone formation was more advanced in defects that had been implanted with the <I>h</I>PDCs/PFO‐HPs than in defects implanted with the <I>h</I>PDCs/PBS‐HP. Thus, PFO‐HPs are a promising tissue engineering approach to repair challenging bone defects and regenerate structurally organized bone tissue with 3D architecture.</P>
Hwang, Sun‐,Goo,Chapagain, Sandeep,Han, A‐,Reum,Park, Yong Chan,Park, Hyeon Mi,Kim, Yong Hwan,Jang, Cheol Seong Munksgaard 2017 Physiologia plantarum Vol.161 No.3
<P>Arsenic (As) accumulation adversely affects the growth and productivity of plants and poses a serious threat to human health and food security. In this study, we identified one As‐responsive <B>R</B>eally <B>I</B>nteresting <B>N</B>ew <B>G</B>ene (RING) E3 ubiquitin ligase gene from rice root tissues during As stress. We named it <I>Oryza sativa</I> As‐Induced RING E3 ligase 2 (<I>OsAIR2</I>). Expression of <I>OsAIR2</I> was induced under various abiotic stress conditions, including heat, salt, drought and As exposure. Results of an in vitro ubiquitination assay showed that OsAIR2 possesses an E3 ligase activity. Within the cell, OsAIR2 was found to be localized to the Golgi apparatus. Using yeast two‐hybrid (Y2H) assay, the 3‐ketoacyl‐CoA thiolase (KAT) protein was identified as an interaction partner. We found that the <I>O. sativa</I> KAT1 (OsKAT1) is localized to the cytosol and peroxisomes. Moreover, in vitro pull‐down assay verified the physical interaction between OsAIR2 and OsKAT1. Interestingly, in vitro ubiquitination assay and in vivo proteasomal degradation assay revealed that OsAIR2 ubiquitinates OsKAT1 and promotes the degradation of OsKAT1 via the 26S proteasome degradation pathway. Heterogeneous overexpression of OsAIR2 in <I>Arabidopsis</I> improved the seed germination and increased the root length under arsenate stress conditions. Therefore, these results suggest that OsAIR2 may be associated with the plant response to As stress and acts as a positive regulator of As stress tolerance.</P>
Hwang, Sun‐,Goo,Kim, Jung Ju,Lim, Sung Don,Park, Yong Chan,Moon, Jun‐,Cheol,Jang, Cheol Seong Munksgaard 2016 Physiologia plantarum Vol.158 No.2
<P>Ubiquitination‐mediated protein degradation via Really Interesting New Gene (RING) E3 ligase plays an important role in plant responses to abiotic stress conditions. Many plant studies have found that RING proteins regulate the perception of various abiotic stresses and signal transduction. In this study, <I>Oryza sativa salt‐induced RING Finger Protein 1</I> (<I>OsSIRP1</I>) gene was selected randomly from 44 <I>Oryza sativa RING Finger Proteins</I> (<I>OsRFPs</I>) genes highly expressed in rice roots exposed to salinity stress. Transcript levels of <I>OsSIRP1</I> in rice leaves after various stress treatments, including salt, heat, drought and hormone abscisic acid (ABA), were observed. Poly‐ubiquitinated products of <I>OsSIRP1</I> were investigated via an in vitro ubiquitination assay.35S:<I>OsSIRP1</I>‐EYFP was distributed in the cytosol of untreated and salt‐treated rice protoplasts. Heterogeneous overexpression of <I>OsSIRP1</I> in <I>Arabidopsis</I> reduced tolerance for salinity stress during seed germination and root growth. Our findings indicate that <I>OsSIRP1</I> acts as a negative regulator of salinity stress tolerance mediated by the ubiquitin 26S proteasome system.</P>