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Journal of Hydrodynamics 2013年第2期25卷 183-195页

作者： sohn chang hyun SON Jong Hyeon PARK Il Seouk School of Mechanical Engineering Kyungpook National University

A dimple appears on a free surface while rotating a cylinder tank filled with liquid. The dimple starts to concentrically deeper to a drain port at the bottom center of the tank. Over time, the dimple penetrates the drain port, a free surface forms a long and slender string shape in the tank, and a so-called vortexing （air core） phenomenon occurs. The generation of a vortex core depends on the size of the tank and drain port, and on the properties of the liquid in the tank. In this study, the liquid level and the time at which the vortex core is initially generated are numerically investigated using different values of tank diameter, drain port diameter, and ini- tial tank rotational speeds. Instead of a full three-dimensional analysis, a two-dimensional axisymmetric simulation is conducted. The momentum conservation equation in the circumferential direction is additionally solved in the two-dimensional mesh system. Several non-dimensional variables are created： the ratio of the air core generation distance and tank diameter, the diameter ratio of the tank and drain port, the rotational Reynolds number, the rotational Froude number, and the rotational Weber number. Finally, the non-dimensional air core generation distance is correlated with the other non-dimensional parameters.

关键词： air core vortex core dip penetration vortexing draining

IL-1β activates p44/42 and p38 mitogen-activated protein kinases via different pathways in cat esophageal smooth muscle cells

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World Journal of Gastroenterology 2006年第5期12卷 716-722页

作者： Tai Sang Lee hyun Ju Song Ji Hoon Jeong Young Sil Min chang Yell Shin Uy Dong sohn Department of Pharmacology College of PharmacyChung-Ang UniversitySeoul 156-756Republic of Korea Research Laboratory Dong-A Pharmaceuticals Co.LtdKyunggidoRepublic of Korea

AIM： To examine the pathway related to the IL-1β induced activation of mitogen-activated protein （MAP） kinases in cat esophageal smooth muscle cells. METHODS： Culture of the esophageal smooth muscle cells from cat was prepared. Specific inhibitors were treated before applying the IL-β3. Western blot analysis was performed to detect the expressions of COX, iNOS and MAP kinases. RESULTS： In the primary cultured cells, although IL-β3 failed to upregulate the COX and iNOS levels, the levels of the phosphorylated forms of 1344142 HAP kinase and p38 MAP kinase increased in both concentration- and time-dependent manner, of which the level of activation reached a maximum within 3 and 18 h, respectively. The pertussis toxin reduced the level of p44/42 MAP kinase phosphorylation. Tyrphostin 51 and genistein also inhibited this activation. Neomycin decreased the density of the p44/42 HAP kinase band to the basal level. Phosphokinase C （PKC） was found to play a mediating role in the IL-1β-induced p44/42 MAP kinase activity. In contrast, the activation of p38 MAP kinase was inhibited only by a pretreatment with forskolin, and was unaffected by the other compounds. CONCLUSION： Based on these results, IL-1β-induced p44/42 MAP kinase activation is mediated by the Gi protein, tyrosine kinase, phospholipase C （PLC） and PKC. The pathway for p38 MAP kinase phosphorylation is different from that of p44/42 MAP kinase, suggesting that it plays a different role in the cellular response to IL- 1β.

关键词： IL-1β MAP kinase Esophageal smoothmuscle cells

Therapeutic effect of DA-9601 on chronic reflux gastritis induced by sodium taurocholate in rats

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World Journal of Gastroenterology 2005年第47期11卷 7430-7435页

作者： Tae Young Oh chang Yell Shin Yong Sung sohn Dong Hwan Kim Byoung Ok Ahn Eun Bang Lee Cho hyun Park Dong-A Pharmaceutical Research Institute YonginKorea Department of General Surgery Catholic University of MedicineSeoulKorea

AIM: To investigate the therapeutic effects of DA-9601 on sodium taurocholate (TCA)-induced chronic reflux gastritis in SD ***: In this study, we have investigated the therapeutic effects of DA-9601 on chronic erosive and atrophic gastritis induced by 6 mo of TCA administration (5 mmol/L in drinking water) in SD rats. RESULTS: Four weeks of DA-9601 administration (0.065%, 0.216% in rat chow), following the withdrawal of TCA treatment, resulted in a significant decrease in total length of erosions in rats in a dose-dependent manner. Furthermore, the indicators of atrophic gastritis, such as reduced mucosal thickness and reduction in the number of parietal cells, were improved by the administration of DA-9601 in a dose-related manner. DA-9601 also attenuated inflammatory cell infiltration and the proliferation of collagenous fiber in the gastric mucosa. The improvement in the reduction of the gastric mucus was observed in the rats receiving a high dose of DA-9601 (0.216%). The therapeutic effect of DA-9601 on experimental chronic erosive gastritis was superior to that of rebamipide (1.08% in rat chow). Biochemical analyses showed increased mucosal prostaglandin E2 and reduced glutathione levels by DA-9601 treatment. CONCLUSION: We suggest that DA-9601 is apromising agent for the treatment of chronic erosive and atrophic gastritis with an etiological factor of bile reflux. Increasedmucosal prostaglandin E2 and reduced glutathione by DA-9601 treatment may be therapeutic mechanisms for chronic erosive and atrophic gastritis.

关键词： DA-9601 Reflux gastritis Erosive gastritis Atrophic gastritis Sodium taurocholate

Grain size dependence of flow stress in ECAPed Ti with constant texture

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中国有色金属学会会刊：英文版 2012年第S3期22卷 673-677页

作者： chang-Young hyun Ho-Kyung KIM Department of Materials Science and Engineering Seoul National University of Science and Technology Department of Automotive Engineering Seoul National University of Science and Technology

The effect of grain size on the flow stress in an ECAPed Ti with a constant texture was investigated,assuming that 2,4,5 and 6 passes microstructures have a similar *** average size of recrystallized grains decreased to 0.5 μm,0.4 μm,and 0.3 μm with respect to the ECAP pass number of 2,4,and 6,*** ultimate tensile strength (UTS) and yield strength (YS) increase with an increase in the number of *** UTS and YS of the 6 passes ECAPed sample were found to be 740.2 MPa and 580.3 MPa,*** equation for the flow stress of an ECAPed Ti with a constant texture as a function of the strain and grain size was derived for the ECAPed *** following equation was finally obtained:σ(ε)=103.9+1825ε-9.6ε1/2·d-1/2+8.3d-1/2.

关键词： Ti mechanical properties grain size flow stress equal channel angular pressing

High-Throughput Pb Recycling for Perovskite Solar Cells Using Biomimetic Whitlockite

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Energy & Environmental Materials 2023年第3期6卷 170-176页

作者： Jung Sug Hong Hee Jung Kim chang Hwun sohn Oh Yeong Gong Jin Hyuk Choi Kang Hee Cho Gill Sang Han Ki Tae Nam hyun Suk Jung Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419Korea

Pb contamination in aquatic environments causes severe pollution;therefore,harmless absorbents are *** this study,we report a novel synthesis of whitlockite(WH,Ca_(18)Mg_(2)(HPO_(4))_(2)(PO_(4))_(12)),which is the second most abundant biomineral in human bone,and its application as a high-performing Pb^(2+)***(HAP)and WH are prepared via a simple precipitation *** Pb2+absorption performance and mechanism of the synthesized biominerals are investigated in aqueous solutions at neutral *** results demonstrate that WH exhibits an excellent Pb2+absorption capacity of 2339 mg g^(−1),which is 1.68 times higher than the recorded value for ***,the absorbed Pb^(2+) ions are recycled into high-purity PbI_(2).This is employed as a precursor for the fabrication of perovskite solar cells(PSCs),resulting in a conversion efficiency of 19.00%comparable to that of commercial PbI2 powder(99.99%purity).Our approach provides an efficient way to remove Pb^(2+)ions from water and reuse them in the recycling of PSCs.

关键词： Pb absorption Pb recycling perovskite solar cells water purification whitlockite

Velocity Profiles between Two Baffles in a Shell and Tube Heat Exchanger

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Journal of Thermal Science 2015年第4期24卷 356-363页

作者： Tae-hyun chang chang-Hoan Lee Hae-Soo Lee Kwon-Soo Lee Senior Research Fellow of RESEAT Korea Institute of Science and Technology Information Korea Institute of Science and Technology Information Postdoctoral Research Fellow School of Mechanical Engineering of Kyungnam University International University of Korea

Heat exchangers are extensively utilized for waste heat recovery,oil refining,chemical processing,and steam *** this study,velocity profiles are measured using a 3D particle image velocimetry(PIV)system between two baffles in a shell and tube heat exchanger for parallel and counter *** PIV and computational fluid dynamics results show the occurrence of some strong vectors near the *** vectors are assumed due to the clearance between the inner tubes and the front ***,the major parts of the vectors are moved out through the bottom opening of the rear baffle,and other vectors produce a large circle between the two *** simulations are conducted to investigate the effects of the baffle on the heat exchanger using the Fluent *** k-εturbulence model is employed to calculate the flows along the heat exchanger.

关键词： Baffle P1V Shell and tube heat exchanger Cut off ratio CFD

Clinical impact of atypical endoscopic features in rectal neuroendocrine tumors

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World Journal of Gastroenterology 2015年第47期21卷 13302-13308页

作者： Jong Hee hyun Seong Dae Lee Eui Gon Youk Jae Bum Lee Enu-Jung Lee Hee Jin chang Dae Kyung sohn Center for Colorectal Cancer National Cancer Center Department of Surgery Daehang Hospital

AIM: To validate the association between atypical endoscopic features and lymph node metastasis(LNM).METHODS: A total of 247 patients with rectal neuroendocrine tumors(NETs) were analyzed. Endoscopic images were reviewed independently by two endoscopists, each of whom classified tumors by sized and endoscopic features, such as shape, color, and surface change(kappa coefficient 0.76 for inter-observer agreement). All of patients underwent computed tomography scans of abdomen and pelvis for evaluation of LNM. Univariate and multivariate analyses were performed to identify the factors associated with LNM. Additionally, the association between endoscopic atypical features and immunohistochemical staining of tumors was ***: Of 247 patients, 156(63.2%) were male and 15(6.1%) were showed positive for LNM. On univariate analysis, tumor size(P changes(P changes were independent risk factors for LNM. The likelihood of atypical endoscopic features increased as tumor size increased. Atypical endoscopic features were associated with LNM in rectal NETs < 10 mm(P = 0.005) and 10-19 mm(P = 0.041) in diameter. Immunohistochemical staining showed that the rate of atypical endoscopic features was higher in non L-cell ***: Atypical endoscopic features as well as tumor size are predictive factors of LNM in patients with rectal NETs.

关键词： Rectal neuroendocrine tumor Colonoscopy Lymph node metastasis

Flexible highly-effective energy harvester via crystallographic and computational control of nanointerfacial morphotropic piezoelectric thin film

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Nano Research 2017年第2期10卷 437-455页

作者： chang Kyu Jeong Sung Beom Cho Jae hyun Han Dae Yong Park Suyoung Yang Kwi-II Park Jungho Ryu Hoon sohn Yong-Chae Chung Keon Jae Lee Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro Yuseong-gu Daejeon 34141 Republic of Korea KAISTInstitute for the NanoCentury (KINC) 291 Daehak-ro Yuseong-gu Daejeon 34141 Republic of Korea Division of Materials Science and Engineering Hanyang University 222 Wangsimni-ro Seongdong-gu Seou104763 Republic of Korea Department of Civil and Environmental Engineering KAIST 291 Daehak-ro Yuseong-gu Daejeon 34141 Republic of Korea Department of Energy Engineering Gyeongnam National University of Science and Technology 33 Dongjin-ro Jinju Gyeongnam 52725 Republic of Korea Functional Ceramic Group Korea Institute of Materials Science (KIMS) 797 Changwon-daero Seongsan-gu Changwon Gyeongnam.51508 Republic of Korea

Controlling the properties of piezoelectric thin films is a key aspect for designing highly efficient flexible electromechanical devices. In this stud）~ the crystallographic phenomena of PbZr1-xTixO3 （PZT） thin films caused by distinguished interfacial effects are deeply investigated by overlooking views, including not only an experimental demonstration but also ab initio modeling. The polymorphic phase balance and crystallinity, as well as the crystal orientation of PZT thin films at the morphotropic phase boundary （MPB）, can be stably modulated using interfacial crystal structures. Here, interactions with MgO stabilize the PZT crystallographic system well and induce the texturing influences, while the PZT film remains quasi-stable on a conventional A1203 wafer. On the basis of this fundamental understanding, a high-output flexible energy harvester is developed using the controlled-PZT system, which shows significantly higher performance than the unmodified PZT generator. The voltage, current, and power densities are improved by 556%, 503%, and 822%, respectively, in comparison with the previous flexional single-crystalline piezoelectric device. Finally, the improved flexible generator is applied to harvest tiny vibrational energy from a real traffic system, and it is used to operate a commercial electronic unit. These results clearly indicate that atomic-scale designs can produce significant impacts on macroscopic applications.

关键词： energy harvesting morphotropic phaseboundary (MPB) piezoelectric first-principles calculation lead zirconium titanate(PZT)

Comparative study on discharge conditions in micro-hole electrical discharge machining of tungsten carbide (WC-Co) material

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中国有色金属学会会刊：英文版 2009年第B9期19卷 114-118页

作者： hyun-Seok TAK chang-Seung HA Dong-hyun KIM Ho-Jun LEE Hae-June LEE Myung-chang KANG National Core Research Center for Hybrid Materials Solution Pusan National University Department of Electrical Engineering Pusan National University

WC-Co is used widely in die and mold industries due to its unique combination of hardness, strength and wear-resistance. For machining difficult-to-cut materials, such as tungsten carbide, micro-electrical discharge machining(EDM) is one of the most effective methods for making holes because the hardness is not a dominant parameter in EDM. This paper describes the characteristics of the discharge conditions for micro-hole EDM of tungsten carbide with a WC grain size of 0.5 μm and Co content of 12%. The EDM process was conducted by varying the condenser and resistance values. A R-C discharge EDM device using arc erosion for micro-hole machining was suggested. Furthermore, the characteristics of the developed micro-EDM were analyzed in terms of the electro-optical observation using an oscilloscope and field emission scanning electron microscope.

关键词：电火花加工碳化钨钴难切削材料硬质合金放电扫描电子显微镜微孔模具行业

Applying Job Shop Scheduling to SMEs Manufacturing Platform to Revitalize B2B Relationship

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Computers, Materials & Continua 2023年第3期74卷 4901-4916页

作者： Yeonjee Choi hyun Suk Hwang chang Soo Kim Department of Information Systems Pukyong National UniversityBusan608737Korea Research Center Hanyoung DSInc.Seoul07600Korea

A small and medium enterprises(SMEs)manufacturing platform aims to perform as a significant revenue to SMEs and vendors by providing scheduling and monitoring *** optimal job shop scheduling is generated by utilizing the scheduling system of the platform,and a minimum production time,i.e.,makespan decides whether the scheduling is optimal or *** scheduling result allows manufacturers to achieve high productivity,energy savings,and customer *** in Industry 4.0 requires dynamic,uncertain,complex production environments,and customer-centered *** paper proposes a novel method for solving the difficulties of the SMEs manufacturing by applying and implementing the job shop scheduling system on a SMEs manufacturing *** primary purpose of the SMEs manufacturing platform is to improve the B2B relationship between manufacturing companies and *** platform also serves qualified and satisfactory production opportunities for buyers and producers by meeting two key factors:early delivery date and fulfillment of processing as many orders as *** genetic algorithm(GA)-based scheduling method results indicated that the proposed platform enables SME manufacturers to obtain optimized schedules by solving the job shop scheduling problem(JSSP)by comparing with the real-world data from a textile weaving factory in South *** proposed platform will provide producers with an optimal production schedule,introduce new producers to buyers,and eventually foster relationships and mutual economic interests.

关键词： Manufacturing platform job shop scheduling problem(JSSP) genetic algorithm optimization textile process