检索结果-南通市图书馆

Acta Metallurgica Sinica(English Letters) 2016年第12期29卷 1107-1118页

作者： jeong kil kim Hae Ji Park Deog Nam Shim Doosan Heavy Industries and Construction ChangwonGeongnam Korea

It is well known that solid solution-strengthened alloy 617 and γ′ precipitation-strengthened alloy 263 have excellent mechanical properties and corrosion resistance at high temperatures. Hyper-supercritical power plants work at temperatures above 700 ℃, and these superalloys are considered candidate materials for steam turbines components of these power plants. In this study, gas tungsten arc weldability of these superalloys was evaluated, and the effects of post- weld heat treatment （PWHT） on the microstructural characteristics and the mechanical properties of their weld metals were investigated. Scanning transmission electron microscopy, energy-dispersive spectroscopy and electron probe microanalysis were utilized for the investigation. The experimental results confirmed that these weld metals had different characteristics in microstructure and mechanical properties. PWHT resulted in the precipitation of intergranular carbides, γ′ particles and an increase in tensile strength of these superalloy weld metals. Furthermore, fine γ′ particles, which were not detected in the as-welded metal of alloy 263, were precipitated after PWHT and those particles were the reason for the drastic increase in tensile strength.

关键词： Superalloy Welding Precipitation Segregation

Analytical evaluation and experimental validation on dynamic rocking behavior for shallow foundation considering structural response

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2022年第1期21卷 37-51页

作者： kil-Wan Ko jeong-Gon Ha Dong-Soo kim Department of Civil and Environmental Engineering UC BerkeleyCalifornia 94720USA Advanced Structures and Seismic Safety Research Division Daejeon 34057Korea Department of Civil and Environmental Engineering KAISTDaejeon 34141Korea

The challenge in the practical application of rocking foundations is the estimation of its performance,particularly the rotation angle,during a strong *** this study,the dynamic rocking behavior for a shallow foundation considering structural response was evaluated through two analytical approaches:the conventional soil-foundation-structure interaction(SFSI)governing equation of a single-degree-of-freedom(SDOF)structure on a rocking shallow foundation,and the Housner rocking model(i.e.,a rocking rigid block on a rigid base).Both approaches were validated with dynamic centrifuge *** test models consisted of a soft soil deposit,a shallow rectangular foundation,and an SDOF structure dominated by a bending behavior.A total of 11 foundation-structure systems and six seismic waves,including recorded earthquake signals and sinusoidal waves,were *** results showed that the conventional SFSI equation well predicted the maximum rotation during strong ***,this method was less accurate regarding the rotational phase information and maximum rotation of the foundation during weak *** the other hand,although the modified Housner′s rocking model required five parameters relevant to a soil-foundation-structure system,it overestimated the maximum rotation of the foundation when compared with the results from dynamic centrifuge tests.

关键词： soil-foundation-structure interaction maximum rotation angle rocking foundation Housner rocking model dynamic centrifuge test

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

在线全文

学校读者我要写书评

暂无评论

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

Protective Effect of Brassica napus *** against Inflammation Response in RAW 264.7 Cells

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Integrative Medicine 2021年第4期27卷 273-279页

作者： Su-Hyeon Cho Song Rae kim Myeong Seon jeong Miri Choi SeonJu Park kil-Nam kim Chuncheon Center Korea Basic Science InstituteChuncheon(24341)Republic of Korea

Objective:To demonstrate the anti-inflammatory activity of Brassica napus ***(BNH)in lipopolysaccharide(LPS)-stimulated RAW 264.7 ***:Composition analysis of BNH was conducted via gas chromatography-mass spectrometry after BNH were *** nitric oxide(NO)production was measured using the Griess *** E2(PGE2)production was evaluated with enzyme-linked immunosorbent *** effects of BNH on LPS-induced pro-inflammatory enzymes including inducible nitric oxide synthase(iNOS)and cyclooxygenase-2(COX-2)were evaluated using Western blot ***,phosphorylation of nuclear factor-kappa B(N F-k B)and nuclear translocation of N F-k B p65 were evaluated with Western blot analysis and immunofluorescence staining,***:Compared with LPS-stimulated cells,BNH markedly decreased the generation of NO and PGE_(2)in LPS-stimulated RAW 264.7 cells(P<0.01 or P<0.05).Moreover,BNH inhibited protein levels of iNOS and COX-2(P<0.01).Phosphorylation of NF-k B and nuclear translocation of NF-k B p65 was significantly inhibited by BNH(P<0.01 or P<0.05).Conclusion:The anti-inflammatory activities of BNH were mediated via blockage of the N F-k B signaling pathways in LPS-stimulated RAW 264.7 cells.

关键词： Brassica napus L. inflammation lipopolysaccharide RAW 264.7 cells hydrosols

Critical cooling rate on carbide precipitation during quenching of austenitic manganese steel

在线全文

学校读者我要写书评

暂无评论

China Foundry 2010年第2期7卷 178-182页

作者： Youn-Soo Ham jeong-Tae kim Si-Young Kwak jeong-kil Choi Woo-Young Yoon Daeyang R-Tech.Co. Ltd290-28Daehwa-DongDaeduk-GuDaejeonKorea e-Design Center KITECH7-47Songdo-DongYeonsu-GuIncheon 406-800Korea Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul 136-701Korea

Critical cooling rate to avoid carbide precipitation during quenching of austenitic manganese steel was investigated by means of optical microscopy,image analyzer and numerical *** efficient heat treatment analysis program including temperature-dependent material properties was developed for the prediction of cooling rate and probability of carbide precipitation during quenching by finite difference ***-dependent heat transfer coefficient was adopted to achieve more precise *** ratio of carbide precipitation was measured by image analyzer to determine the critical point of carbide ***-dependent critical cooling rate at that point was calculated by the developed numerical ***,the probability of carbide precipitation on the whole area of specimen can be predicted by the proposed numerical program and the numerical result of a specimen was compared with the experimental result.

关键词： austenitic manganese steel carbide precipitation quenching critical cooling rate

Virtual Mold Technique in Thermal Stress Analysis during Casting Process

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第3期24卷 359-363页

作者： Si-Young Kwak Jae-Wook Baek jeong-Ho Nam jeong-kil Choi E-Design Center Korea Institute of Industrial Technology Department of Virtual Engineering Korea University of Science & Technology

It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.

关键词： Casting process Thermal stress analysis Virtual mold

Die Casting Mold Design of the Thin-walled Aluminum Case by Computational Solidification Simulation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第3期24卷 383-388页

作者： Young-Chan kim Chang-Seog Kang Jae-Ik Cho Chang-Yeol jeong Se-Weon Choi Sung-kil Hong Korea Institute of Industrial Technology Chonnam National University

Recently, demand for the lightweight alloy in electric/electronic housings has been greatly increased. However, among the lightweight alloys, aluminum alloy thin-walled die casting is problematic because it is quite difficult to achieve sufficient fluidity and feedability to fill the thin cavity as the wall thickness becomes less than 1mm. Therefore, in this study, thin-walled die casting of aluminum （Al-Si-Cu alloy： ALDC 12） in size of notebook computer housing and thickness of 0.8 mm was investigated by solidification simulation （MAGMA soft） and actual casting experiment （Buhler Evolution B 53D）. Three different types of gating design, finger, tangential and split type with 6 vertical runners, were simulated and the results showed that sound thin-walled die casting was possible with tangential and split type gating design because those gates allowed aluminum melt to flow into the thin cavity uniformly and split type gating system was preferable gating design comparing to tangential type gating system at the point of view of soundness of casting and distortion generated after solidification. Also, the solidification simulation agreed well with the actual die-casting and the casting showed no casting defects and distortion.

关键词： Aluminum casting alloy Thin-wall die casting Solidification simulation

Effectiveness of contrast-enhanced harmonic endoscopic ultrasound for the evaluation of solid pancreatic masses

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2014年第2期20卷 518-524页

作者： Jin-Seok Park Hyung kil kim Byoung Wook Bang Sang Gu kim Seok jeong Don Haeng Lee Digestive Disease Center Department of Internal MedicineInha University School of MedicineIncheon 400-711South Korea

AIM:To evaluate the usefulness of contrast-enhanced harmonic endoscopic ultrasound(CH-EUS)in differentiating between pancreatic adenocarcinomas and other pancreatic ***:This retrospective cohort study evaluated90 patients who were seen between November 2010and May *** these patients had solid pancreatic masses that had a hypoechoic appearance on *** patients underwent CH-EUS to evaluate this diagnostic method’s *** mass lesions observed on CH-EUS were classified into three categories based on their echo intensity:hypoenhanced,isoenhanced,and hyperenhanced *** adjusted the sensitivity and the specificity of each category for detecting *** also estimated the accuracy of CH-EUS by comparing it to a pathological ***:Of the 90 patients,62 had a pancreatic ***-seven out of 62 pancreatic adenocarcinomas showed a hypoenhanced pattern on *** sensitivity was 92%,the specificity 68%and the accuracy approximately 82%.The area under the curve of the receiver operating characteristic analysis for CH-EUS was *** is a significant association between the hypoenhanced pattern on CH-EUS and pancreatic duct adenocarcinoma(χ2=35.264,P<0.001).In pathological examinations,the number of specimens for EUS-fine needle aspiration(EUS-FNA)was considered insufficient for diagnosis in three patients,and in two patients,the results were reported to be negative for *** masses in all five patients revealed a hypoenhanced pattern with *** patients were diagnosed with pancreatic adenocarcinoma based on the pathology results of a biopsy,and the remaining two patients were clinically diagnosed with ***:CH-EUS is useful for distinguishing between pancreatic adenocarcinoma and other pancreatic *** a pancreatic mass shows a hypoenhanced pattern on CH-EUS but involves either insufficient samples or negative results with EUS-FNA,clinicians might consider perfo

关键词： Pancreas neoplasm Endoscopic ultrasound SonoVue Contrast media Microbubbles

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

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Changes in Reverse Cardiac Remodeling after Percutaneous Atrial Septal Defect Closure in Children and Adults

在线全文

学校读者我要写书评

暂无评论

Congenital Heart Disease 2021年第3期16卷 211-220页

作者： Geena kim Hong Ryang kil Department of Pediatrics Chungnam National University Sejong HospitalChungnam National University School of MedicineSejong30099Korea Department of Pediatrics Chungnam National University HospitalChungnam National University School of MedicineDaejeon35105Korea

Background:The influence of the timing of transcatheter atrial septal defect(ASD)closure on ventricular remodeling at 6 months after ASD closure is *** study investigated changes in cardiac remodeling after transcatheter closure of large ASDs according to patient age at the time of the ***:In this study,41 children and 43 adults underwent percutaneous closure of a large *** remodeling was assessed by two-dimensional echocardiography and electrocardiography before and at 6 months after ASD ***:The age of the children and adults were 2.8±3.1 and 50.0±15.6 years,*** Qp/Qs ratio of all patients was 2.24±*** right atrial(RA)maximal dimension and right ventricular(RV)transverse diameter were significantly decreased and the left ventricular(LV)dimension was significantly increased at 6 months after ASD ***,the difference in RA and RV dimension changes between the groups was not statistically *** difference in left atrial(LA)dimension changes between the groups was also not statistically significant,but the LV dimension significantly increased in children compared with that in adults(P=0.018).The RV/LV ratio was decreased after ASD closure,and a significant difference was found in the RV/LV ratio changes between the *** ECG,the PR interval was significantly more decreased in adults than in children(P=0.003).Conclusions:In conclusion,the LV diameter was significantly more increased in children than in adults at 6 months after percutaneous ASD ***,cardiac remodeling after percutaneous ASD closure varies in children and adults.

关键词： Atrial septal defect ventricular remodeling