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

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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

Chondrogenesis of periodontal ligament stem cells by transforming growth factor-β3 and bone morphogenetic protein-6 in a normal healthy impacted third molar

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International Journal of Oral Science 2013年第1期5卷 7-13页

作者： Sunyoung choi tae-Jun Cho Soon-Keun Kwon Gene Lee Jaejin Cho Laboratory of Developmental Biology and Stem Cell Differentiation/Transplantation Department of Dental Regenerative BiotechnologySchool of DentistrySeoul National University Dental Research Institute School of DentistrySeoul National University Laboratory of Molecular Genetics School of DentistrySeoul National University

The periodontal ligament-derived mesenchymal stem cell is regarded as a source of adult stem cells due to its ***, the proof of chondrogenic potential of the cells is ***,we investigated the chondrogenic differentiation capacity of periodontal ligament derived mesenchymal stem cells induced by transforming growth factor(TGF)-p3 and bone morphogenetic protein(BMP)-*** isolation of periodontal ligament stem cells(PDLSCs) from human periodontal ligament,the cells were cultured in Dulbecco’s modified Eagle’s medium(DMEM) with 20%fetal bovine serum(FBS).A mechanical force initiated chondrogenic differentiation of the *** chondrogenic differentiation,10μg·LTGF-β3 or 100μg·LBMP-6 and the combination treating group for synergistic effect of the growth *** analyzed the PDLSCs by fluorescence-activated cell sorting and chondrogenesis were evaluated by glycosaminoglycans assay,histology,immunohistochemistry and genetic *** showed mesenchymal stem cell properties proved by FACS *** contents were increased 217%by TGF-β3 and 220%by BMP-6. The synergetic effect of TGF-β3 and BMP-6 were shown up to 281%compared to *** combination treatment increased Sox9, aggrecan and collagen II expression compared with not only controls,but also TGF-P3 or BMP-6 single treatment *** histological analysis also indicated the chondrogenic differentiation of PDLSCs in our *** results of the present study demonstrate the potential of the dental stem cell as a valuable cell source for chondrogenesis,which may be applicable for regeneration of cartilage and bone fracture in the field of cell therapy.

关键词： bone morphogenetic protein-6 chondrogenesis growth factor periodental ligament cell stem cell transforming growth factor-β3

Nanocrystalline Iron Pyrophosphate-Regulated Amorphous Phosphate Overlayer for Enhancing Solar Water Oxidation

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Nano-Micro Letters 2022年第12期14卷 387-400页

作者： Chengkai Xia Yuankai Li Minyeong Je Jaekyum Kim Sung Min Cho Chang Hyuck choi Heechae choi tae-Hoon Kim Jung Kyu Kim School of Chemical Engineering Sungkyunkwan University(SKKU)2066 Seobu-roJangan-guSuwon 16419Republic of Korea Theoretical Materials and Chemistry Group Institute of Inorganic ChemistryUniversity of CologneGreinstr.650939 CologneGermany Department of Chemistry Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Materials Science and Engineering Engineering Research CenterChonnam National UniversityGwangju 61186Republic of Korea

A rational regulation of the solar water splitting reaction pathway by adjusting the surface composition and phase structure of catalysts is a substantial approach to ameliorate the sluggish reaction kinetics and improve the energy conversion *** this study,we demonstrate a nanocrystalline iron pyrophosphate(Fe_(4)(P_(2)O_(7))_(3),FePy)-regulated hybrid overlayer with amorphous iron phosphate(FePO_(4),FePi)on the surface of metal oxide nanostructure with boosted photoelectrochemical(PEC)water *** manipulating the facile electrochemical surface treatment followed by the phosphating process,nanocrystalline FePy is localized in the FePi amorphous overlayer to form a heterogeneous hybrid *** FePy-regulated hybrid overlayer(FePy@FePi)results in significantly enhanced PEC performance with long-term *** with the homogeneous FePi amorphous overlayer,FePy@FePi can improve the charge transfer efficiency more significantly,from 60% of FePi to 79%of FePy@*** density-functional theory calculations reveal that the coexistence of FePi and FePy phases on the surface of metal oxide results in much better oxygen evolution reaction kinetics,where the FePi was found to have a typical down-hill reaction for the conversion from OH*to O_(2),while FePy has a low free energy for the formation of OH*.

关键词： Water oxidation Photoelectrochemical cell Metal pyrophosphate Electrochemical surface treatment

Delayed hypersensitivity reaction resulting in maculopapular-type eruption due to entecavir in the treatment of chronic hepatitis B

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World Journal of Gastroenterology 2014年第42期20卷 15931-15936页

作者： Jeong tae Kim Hye Won Jeong Ki Hwa choi tae Young Yoon Nohyun Sung Young Ki choi Eun Ha Kim Hee Bok Chae Department of Internal Medicine College of Medicine and Medical Research Institute Chungbuk National University Department of Dermatology College of Medicine and Medical Research Institute Chungbuk National University Department of Pathology College of Medicine and Medical Research Institute Chungbuk National University Department of Microbiology College of Medicine and Medical Research Institute Chunguk National University

Several clinical trials have demonstrated the potent antiviral efficacy of entecavir (ETV), and this relatively new nucleoside analogue drug has rapidly become a frequently prescribed therapy for chronic hepatitis B (CHB) worldwide. While the studies have also shown a good overall safety profile for ETV, adverse drug reactions (ADRs) in patients with advanced cirrhosis have been reported and represent a broad spectrum of drug-induced injuries, including lactic acidosis, myalgia, neuropathy, azotemia, hypophosphatemia, muscular weakness, and pancreatitis, as well as immune-mediated responses (i.e., allergic reactions). Cutaneous ADRs associated with ETV are very rare, with only two case reports in the publicly available literature; both of these cases were classified as unspecified hypersensitivity allergic (type I) ADR, but neither were reported as pathologically proven or as evaluated by cytokine release analysis. Here, we report the case of a 45-year-old woman who presented with a generalized maculopapular rash after one week of ETV treatment for lamivudine-resistant CHB. The patient reported having experienced a similar skin eruption during a previous three-month regimen of ETV, for which she had self-discontinued the medication. Histopathological analysis of a skin biopsy showed acanthotic epidermis with focal parakeratosis and a perivascular lymphocytic infiltrate admixed with interstitial eosinophils in the papillary and reticular dermis, consistent with a diagnosis of drug sensitivity. A lymphocyte stimulation test showed significantly enhanced IL-4, indicating a classification of type IVb delayed hypersensitivity. The patient was switched to an adefovir-lamivudine combination regimen and the skin eruption resolved two weeks after the ETV withdrawal. This case represents the first pathologically and immunologically evidenced ETV-induced delayed type hypersensitivity skin reaction reported to date. Physicians should be aware of the potential, although rare, fo

关键词： Entecavir Delayed type hypersensitivity Maculopapular drug eruption Dermatology Adverse drug reaction Chronic hepatitis B

Structural considerations in friction welding of hybrid Al_2O_3-reinforced aluminum composites

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 42-46页

作者： In-Duck PARK Choon-tae LEE Hyun-Soo KIM Woo-Jin choi Myung-Chang KANG Busan Metropolitan City Hall Fundamental Industries Division 2001 Jungang-ro Yeonje-gu Busan 611-735 Korea Department of Automotive & Mechanical Engineering Silla University Research & Development Center Sam-Ho precision 1256-1 Daejeo2-dong Gangseo-gu Busan 618-807 Korea National Core Research Center for Hybrid Materials Solution Pusan National University

Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al203-reinforced aluminum composites were conducted. Metal matrix composites （MMCs） with 37% （volume fraction） aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, while it is considered that the joining efficiency does not increase as the reduction rate of particle size decreases. During the macro-examination of the bonding interlace, a gray discolored region was observed on the bonding interface, and the center of the region was dark gray. After the micro-examination of the bonding interface, base metal made some second particulate formed by condensed alumina particulate but discoloration part distributed minute alumina particulate without second particulate. Consequently, it was also observed that rotational speed of 3 000 r/min and upset pressure of 63.6 MPa showed a very ***.

关键词： friction welding hybrid aluminum composite bonding interface joining efficiency metal matrix composite

Extracts from Paeonia lactiflora Pallas, Rehmannia Glutinosa var. Purpurea Makino, Perilla Frutescens var. Acuta Kudo may increase the endometrial receptivity through expression of leukemia inhibitory factor and adhesion molecules

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Journal of Traditional Chinese Medicine 2019年第1期39卷 15-25页

作者： Eun-Yeong Kim tae-Wook Chung Hee-Jung choi Yeon-Seop Jung Syng-Ook Lee Jun-Yong choi Hyung Sik Kim Sooseong You Myeong Soo Lee Ki-tae Ha School of Korean Medicine and Korean Medical Research Center for Healthy Aging Pusan National UniversityYangsan 50612Republic of Korea Graduate Training Program of Korean Medicine for Healthy-aging Pusan National UniversityYangsan 50612Republic of Korea Department of Food Science and Technology Keimyung UniversityDaegu 42601Republic of Korea National Clinical Research Center for Korean Medicine Korean Medicine Hospital of Pusan National UniversityYangsan 50612Republic of Korea Laboratory of Molecular Toxicology School of PharmacySungKyunKwan UniversitySuwon 16419Republic of Korea Korea Institute of Oriental Medicine Daejeon 34054Republic of Korea

OBJECTIVE: To find out the combination of the extracts from Paeonia lactiflora Pallas(PL), Rehmannia Glutinosa var. Purpurea Makino(RG), Perilla Frutescens var. Acuta Kudo(PF) to increase endometrial ***: Herbal medicines were extracted with boiling water and polysaccharides were *** examined the effect of PL, RG, and PF(PRP), a most effective herbal formula deduced from constitutive ingredient herbs of Antai Yin which is composed of PRP, on the leukemia inhibitory factor(LIF) expression and endometrial ***: The combination of the extracts from PRP induced the LIF expression in Ishikawa cells and increased the adhesion between Ishikawa and JAr cells. In addition, PRP-induced attachment of JAr cells onto Ishikawa cells and expression of adhesion molecules, ITGAV, ITGB5, CD44 s, and Lselectin, are significantly reduced by knock-down of LIF ***: Induced by the combination of the PRP extracts, the adhesion between trophoblast and endometrial cells are mediated by expression of LIF and adhesion molecules. Thus, we suggest the combination of the PRP extracts may be a novel therapy for enhancing embryo implantation rate.

关键词： Paeonia Rehmannia Perilla Embryo implantation Endometrium Leukemia inhibitory factor Cell adhesion molecules

Concurrence of iridocorneal endothelial syndrome in a patient with glaucomatocyclitic crisis

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International Journal of Ophthalmology(English edition) 2014年第2期7卷 384-386页

作者： Jin A choi Yi Ryeung Park tae Yoon La Department of Ophthalmology St.Vincent Hospital College of Medicine Catholic University of Korea SuwonKyonggi-do 442-060 Korea

Dear Sir,Iam Jin A choi,from the Department of Ophthalmology of *** Hospital of Suwon,Kyungki-do,South Korea.I write to present a case report of a young female treated with the diagnosis of Posner-Schlossman syndrome for several years,in which she was ultimately proved to have iridocorneal endothelial(ICE)***-Schlossman syndrome(PS syndrome)is characterized by recurrent attacks of mild anterior uveitis with marked elevation of intraocular pressure(IOP)[1].The exact etiology of this syndrome is not fully established ***,the possible role of herpes simplex virus(HSV)is suggested by a study that revealed DNA evidence of the virus in all aqueous specimens of patients during acute attacks in PS syndrome[1,2].ICE is a spectrum of disease that

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Interface properties and phase formation between surface coated SKD61 and aluminum alloys

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中国有色金属学会会刊：英文版 2009年第4期19卷 875-878页

作者： Se-Weon choi Young-Chan KIM Se-Hun CHANG ik-Hyun OH Joon-Sik PARK Chang-Seog KANG Automotive Components Center Korea Institute of Industrial Technology Division of Advanced Materials Engineering Hanbat National University

The intermediate phase formation and surface protection effects between SKD61 die mold alloys and aluminum alloys were investigated during a simulated die-casting *** surface coatings of SKD61 alloy were carried out via Si pack cementation coatings at 900 ℃ for 10 h and the ε-FeSi phase *** the coated SKD61 alloy was dipped in the liquid aluminum alloy(ALDC12),the surface coated SKD61 alloys showed better surface properties compared with uncoated SKD61 alloys,i.e.,the intermediate phases(FeSiAl compound) were not produced for the coated SKD61 *** coating layer of ε-FeSi served as a diffusion barrier for the formation of FeSiAl compounds.

关键词：表面涂层铝合金接口特性表面合金涂层表面保护合金生产化合物中间相

Topology optimization of reactive material structures for penetrative projectiles

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Defence Technology（防务技术） 2022年第7期18卷 1205-1218页

作者： Shinyu Kim Saekyeol Kim taekyun Kim Sangin choi tae Hee Lee Jung Su Park Sang-Hyun Jung Department of Automotive Engineering Hanyang University222 Wangsimni-roSeongdong-guSeoul04763Republic of Korea The 4th R&D Institute Agency for Defense Development35Yuseong P.O.BoxDaejeon34186Republic of Korea

Recently,reactive materials have been developed for penetrative projectiles to improve impact resistance and energy ***,the design of a reactive material structure,involving shape and size,is challenging because of difficulties such as high non-linearity of impact resistance,manufacturing limitations of reactive materials and high expenses of penetration *** this study,a design optimization methodology for the reactive material structure is developed based on the finite element analysis.A finite element model for penetration analysis is introduced to save the expenses of the *** resistance is assessed through the analysis,and result is calibrated by comparing with experimental *** on the model,topology optimization is introduced to determine shape of the *** design variables and constraints of the optimization are proposed considering the manufacturing limitations,and the optimal shape that can be manufactured by cold spraying is *** on the optimal shape,size optimization is introduced to determine the geometric dimensions of the *** a result,optimal design of the reactive material structure and steel case of the penetrative projectile,which maximizes the impact resistance,is *** the design process proposed in this study,reactive material structures can be designed considering not only mechanical performances but also manufacturing limitations,with reasonable time and cost.

关键词： Reactive material Penetrative projectile Topology optimization Manufacturing constraint Cold gas dynamic spray Additive manufacturing