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Development of Ubiquitous Simulation Service Structure Based on High Performance Computing Technologies

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Journal of Materials Science & Technology 2008年第3期24卷 374-378页

作者： Sang-hyun cho Jeong-Kil choI Center For e-Design KITECH7-47Songdo-DongYeonsu-Ku

The simulation field became essential in designing or developing new casting products and in improving manufacturing processes within limited time, because it can help us to simulate the nature of processing, so that developers can make ideal casting designs. To take the prior occupation at commercial simulation market, so many development groups in the world are doing their every effort. They already reported successful stories in manufacturing fields by developing and providing the high performance simulation technologies for multipurpose. But they all run at powerful desk-side computers by well-trained experts mainly, so that it is hard to diffuse the scientific designing concept to newcomers in casting field. To overcome upcoming problems in scientific casting designs, we utilized information technologies and full-matured hardware backbones to spread out the effective and scientific casting design mind, and they all were integrated into Simulation Portal on the web. It professes scientific casting design on the NET including ubiquitous access way represented by ＂Anyone, Anytime, Anywhere＂ concept for casting designs.

关键词： Parallel computation Message passing interface (MPI) Shared memory processing (SMP) Clustering Ubiquitous

Evaluation of ring surfaces with several coatings for friction,wear and scuffing life

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中国有色金属学会会刊：英文版 2009年第4期19卷 992-996页

作者： Dae-hyun cho Young-Ze LEE School of Mechanical Engineering Sungkyunkwan University

Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and *** engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating ***,it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel *** and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel *** frictional forces,wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear *** tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed *** coatings on the ring specimen were used,such as DLC,TiN,Cr-ceramic and TiAlN,in order to improve the tribological characteristics of the *** coefficients of friction were monitored during the tests,and the wear volumes of the piston ring surfaces with various coatings were *** results show that the DLC coating exhibits better tribological properties than the other *** graphite structure of this coating is responsible for the low friction and wear of the DLC *** TiN and DLC coatings show better scuffing resistance than the other *** TiN and Cr-ceramic coated rings show good wear resistance and high friction.

关键词：涂层表面摩擦评价生活划伤磨损

Mechanical and corrosion properties of full liquid phase sintered WE43 magnesium alloy specimens fabricated via binder jetting additive manufacturing

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Journal of Magnesium and Alloys 2024年第7期12卷 2711-2724页

作者： Dae hyun cho David Dean Alan A.Luo Department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210USA Department of Plastic and Reconstructive Surgery The Ohio State UniversityColumbusOH 43210USA Department of Integrated Systems Engineering The Ohio State UniversityColumbusOH 43210USA

This study investigates full liquid phase sintering as a process of fabrication parts from WE43(Mg-4wt.%Y-3wt.%RE-0.7wt.%Zr)alloy using binder jetting additive manufacturing(BJAM).This fabrication process is being developed for use in producing structural or biomedical ***,this study focused on achieving a near-dense microstructure with WE43 Mg alloy while substantially reducing the duration of sintering post-processing after BJAM part *** optimal process resulted in microstructure with 2.5%porosity and significantly reduced sintering *** improved sintering can be explained by the presence of Y_(2)O_(3)and Nd_(2)O_(3)oxide layers,which form spontaneously on the surface of WE43 powder used in *** layers appear to be crucial in preventing shape distortion of the resulting samples and in enabling the development of sintering necks,particularly under sintering conditions exceeding the liquidus temperature of WE43 *** WE43 specimens rendered by BJAM achieved significant improvement in both corrosion resistance and mechanical properties through reduced porosity levels related to the sintering time.

关键词： Magnesium alloy Liquid phase sintering Additive manufacturing Binder jetting process Biodegradation

White matter changes in 80 mild cognitive impairment patients using magnetic resonance imaging

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Neural Regeneration Research 2009年第9期4卷 654-658页

作者： hyun cho Jee-hyun Kwon Sun-Young Kim Department of Neurology Ulsan University Hospital

BACKGROUND： Many studies have suggested that one possible etiology of mild cognitive impairment is small vessel cerebrovascular disease, which is associated with small subcortical infarcts and white matter abnormalities. These white matter changes have been detected as white matter hyperintensity （WMH） using magnetic resonance imaging. WMH may be associated with frontal lobe dysfunction. OBJECTIVE： To examine white matter changes in mild cognitive impairment patients of different subtypes, and to evaluate the correlation between white matter changes and neuropsychological characteristics, demographic information, vascular risk factors, and mild cognitive impairment subtypes. DESIGN, TIME AND SETTING： The neurophysiological, comparison study was performed at the Department of Neurology Memory Clinic, Ulsan University Hospital, South Korea, between March 2007 and March 2008. PARTICIPANTS： Out of a total of 83 subjects with clinically diagnosed mild cognitive impairment at the out-patient clinic, 3 subjects with severe WMH were excluded. A total of 80 subjects were included in this study. No patients suffered from cognitive impairment induced by neurological diseases, mental disorders, or somatic diseases. In accordance with magnetic resonance imaging results, the patients were assigned to two subtypes： 56 subjects without WMH and 24 subjects with WMH. METHODS： All patients were subjected to a standard neuropsychological battery using the Korean version of the Mini-Mental State Examination, Clinical Dementia Rating, and comprehensive Seoul Neuropsychological Screening Battery. The Clinical Dementia Rating reflected general cognitive function of patients. Results from the Seoul Neuropsychological Screening Battery reflected attention, language function, visuospatial function, verbal memory, nonverbal memory, long-term memory, and frontal/executive function. Magnetic resonance imaging was used to map changes in the brain. MAIN OUTCOME MEASURES： The association between va

关键词： mild cognitive impairment cerebrovascular disease white matter hyperintensity frontal/executive dysfunction

Early gastric cancer presenting as a typical submucosal tumor cured by endoscopic submucosal dissection:A case report

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World Journal of Gastroenterology 2022年第25期28卷 2994-3000页

作者： Joon hyun cho Si hyung Lee Division of Gastroenterology and Hepatology Department of Internal MedicineYeungnam University College of MedicineDaegu 42415South Korea

BACKGROUND Submucosal tumor(SMT)-like gastric cancer is rare,and almost all cases undergo curative surgical treatment because the submucosal layer is usually deeply invaded by tumor cells or because histopathologic types of SMT-like gastric cancer are undifferentiated or poorly *** report has been issued on an SMT-like gastric cancer cured by endoscopic resection alone or on changes in the endoscopic features of this type of tumor over several *** SUMMARY We describe an exceptional case of a 53-year-old male with a 1.5 cm-sized SMTlike lesion covered by normal-appearing mucosa discovered by esophagogastroduodenoscopy(EGD)at the gastric *** ultrasound(EUS)visualized a homogeneous,well-circumscribed hypoechogenic lesion arising from the second sonographic layer with associated subtle obliteration of the third sonographic *** endoscopic biopsy was negative for *** patient refused to undergo an invasive procedure and was subsequently lost to *** years after initial detection,EGD revealed the lesion had become markedly erythematous,and at 4 years after initial EGD it had increased in size to 1.8 cm and developed a central ulcer and a heterogeneous EUS ***,endoscopic submucosal dissection(ESD)was performed,and histopathologic examination revealed a moderately differentiated adenocarcinoma had minutely invaded the submucosal layer(invasion depth 169μm)but without lymphovascular invasion and with negative resection ***,no additional surgical treatment was *** has been followed for 4 years after ESD without any evidence of local or distant *** This report describes an extremely rare case of early gastric cancer presenting as SMT that was cured by ESD after a treatment delay of 4 years and the endoscopic changes that occurred during this *** report highlights the importance of considering the possibility of gastric cancer when SMT is encountered in clini

关键词： Subepithelial lesion Submucosal tumor Early gastric cancer Adenocarcinoma Endoscopic mucosal dissection Case report

Cytomegalovirus ileo-pancolitis presenting as toxic megacolon in an immunocompetent patient: A case report

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World Journal of Clinical Cases 2020年第3期8卷 552-559页

作者： Joon hyun cho Joon Hyuk choi Division of Gastroenterology and Hepatology Department of Internal MedicineYeungnam University College of MedicineDaegu 42415South Korea Department of Pathology Yeungnam University College of MedicineDaegu 42415South Korea

BACKGROUND Cytomegalovirus(CMV) enterocolitis presenting in the form of pancolitis or involving the small and large intestines in an immunocompetent patient is rarely encountered, and CMV enterocolitis presenting with a serious complication, such as toxic megacolon, in an immunocompetent adult has only been reported on a few *** SUMMARY We describe the case of a 70-year-old male with no history of inflammatory bowel disease or immunodeficiency who presented with toxic megacolon and subsequently developed massive hemorrhage as a complication of CMV ileopancolitis. The patient was referred to our institute for abdominal pain and distension. Abdominal X-ray showed marked dilatation of ileum and whole colon without air-fluid level, and sigmoidoscopy with biopsy failed to reveal any specific finding. After 7 d of conservative treatment, massive hematochezia developed, and he was diagnosed to have CMV enterocolitis by colonoscopy with biopsy. Although the diagnosis of CMV enterocolitis was delayed, the patient was treated successfully by repeat colonoscopic decompression and antiviral therapy with intravenous *** This report cautions that CMV-induced colitis should be considered as a possible differential diagnosis in a patient with intractable symptoms of enterocolitis or megacolon of unknown cause, even when the patient is nonimmunocompromised.

关键词： Toxic megacolon Cytomegalovirus Enterocolitis Immunocompetent Case report

Comparison of scoring systems in predicting the severity of acute pancreatitis

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World Journal of Gastroenterology 2015年第8期21卷 2387-2394页

作者： Joon hyun cho Tae Nyeun Kim hyun Hee Chung Kook hyun Kim Division of Gastroenterology and Hepatology Department of Internal Medicine Yeungnam University College of Medicine

AIM:To investigate the prognostic usefulness of several existing scoring systems in predicting the severity of acute pancreatitis(AP).METHODS:We retrospectively analyzed the prospectively collected clinical database from consecutive patients with AP in our institution between January 2011 and December ***,Acute Physiology and Chronic Health Evaluation(APACHE)-Ⅱ,and bedside index for severity in acute pancreatitis(BISAP)scores,and computed tomography severity index(CTSI)of all patients were *** C-reactive protein(CRP)levels were measured at admission(CRPi)and after 24h(CRP24).Severe AP was defined as persistent organ failure for more than 48 *** predictive accuracy of each scoring system was measured by the area under the receiver-operating curve(AUC).RESULTS:Of 161 patients,21(13%)were classified as severe AP,and 3(1.9%)*** significant cutoff values for prediction of severe AP were Ranson≥3,BISAP≥2,APACHE-Ⅱ≥8,CTSI≥3,and CRP24≥*** for Ranson,BISAP,APACHE-Ⅱ,CTSI,and CRP24 in predicting severe AP were 0.69(95%CI:0.62-0.76),0.74(95%CI:0.66-0.80),0.78(95%CI:0.70-0.84),0.69(95%CI:0.61-0.76),and0.68(95%CI:0.57-0.78),***-Ⅱdemonstrated the highest accuracy for prediction of severe AP,however,no statistically significant pairwise differences were observed between APACHE-Ⅱand the other scoring systems,including ***:Various scoring systems showed similar predictive accuracy for severity of *** models are needed in order to achieve further improvement of prognostic accuracy.

关键词： Severity Scoring systems Predictors Acute pancreat

AGE-induced neuronal cell death is enhanced in G2019S LRRK2 mutation with increased RAGE expression

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Translational Neurodegeneration 2018年第1期7卷 1-8页

作者： hyun Jin cho Chengsong Xie Huaibin Cai Department of Biochemistry and Biomedical Sciences Seoul National UniversityCollege of Medicine28 Yungun-dongJongro-guSeoul 110-799South Korea Transgenics Section Laboratory of NeurogeneticsNational Institute on AgingNational Institutes of HealthBuilding 35Room 1A112MSC 370735 Convent DriveBethesdaMD 20892–3707USA

Background:Leucine-rich repeat kinase 2(LRRK2)mutations represent the most common genetic cause of sporadic and familial Parkinson’s disease(PD).Especially,LRRK2 G2019S missense mutation has been identified as the most prevalent genetic cause in the late-onset *** glycation end products(AGEs)are produced in high amounts in diabetes and diverse aging-related disorders,such as cardiovascular disease,renal disease,and neurological *** trigger intracellular signaling pathway associated with oxidative stress and inflammation as well as cell ***,receptor of AGEs,is activated by interaction with AGEs and mediates AGE-induced *** AGE and RAGE are involved in the pathogenesis of mutant LRRK2 is ***:Using cell lines transfected with mutant LRRK2 as well as primary neuronal cultures derived from LRRK2 wild-type(WT)and G2019S transgenic mice,we compared the impact of AGE treatment on the survival of control and mutant cells by *** also examined the levels of RAGE proteins in the brains of transgenic mice and PD patients by western ***:We show that LRRK2 G2019S mutant-expressing neurons were more sensitive to AGE-induced cell death compared to ***,we found that the levels of RAGE proteins were upregulated in LRRK2 G2019S mutant ***:These data suggest that enhanced AGE-RAGE interaction contributes to LRRK2 G2019S mutation-mediated progressive neuronal loss in PD.

关键词： Parkinson’s disease LRRK2 G2019S AGE RAGE Neuronal death

Heat Transfer between Casting and Die during High Pressure Die Casting Process of AM50 Alloy-Modeling and Experimental Results

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Journal of Materials Science & Technology 2008年第1期24卷 131-135页

作者： Zhipeng GUO Shoumei XIONG Sang-hyun cho Jeong-Kil choi Key Laboratory for Advanced Manufacturing by Materials Processing Technology Department of Mechanical Engineering Tsinghua University Beijing 100084 China Advanced Material R＆D Center Korean Institute of Industrial Technology 994-32 Dongchun-Dong Yonsu-Ku Inchon Korea

A method based on die casting experiments and mathematic modeling is presented for the determination of the heat flow density （HFD） and interfacial heat transfer coefficient （IHTC） during the high pressure die casting （HPDC） *** were carried out using step shape casting and a commercial magnesium alloy,*** profiles were measured and recorded using thermocouples embedded inside the die. Based on these temperature readings,the HFD and IHTC were successfully determined and the calculation results show that the HFD and IHTC at the metal-die interface increases sharply right after the fast phase injection process until approaching their maximum values,after which their values decrease to a much lower level until the dies are *** patterns of heat transfer behavior were found between the die and the casting at different *** thinner the casting was,the more quickly the HFD and IHTC reached their steady ***,the values for both the HFD and IHTC values were different between die and casting at different thicknesses.

关键词： : Interfacial heat transfer coefficient High pressure die casting process AM50 Magnesium alloy