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Study on the Wiping Gas Jet in Continuous Galvanizing Line

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Journal of Thermal Science 2011年第3期20卷 242-247页

作者： Yong-Hun kweon Heuy-dong Kim POSCO Technical Research Laboratories 699 Gumho-dong GwangyangJeonnam 545-090 Korea School of Mechanical Engineering Andong National UniversityAndong 760-749 Korea

In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.

关键词： Gas-Jet Wiping Hot-Dip Galvanizing Impact Pressure Coating Thickness

A Study of the Impulse Wave Discharged from the Exits of Two Parallel Tubes

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Journal of Thermal Science 2003年第4期12卷 332-336,356页

作者： Yong-Hun kweon Heuy-dong Kim Toshiaki Setoguchi Toshiyuki Aoki School of Mechanical Engineering Andong National University Andong 760-749 KoreaSchool of Mechanical Engineering Andong National University Andong 760-749 KoreaDepartment of Mechanical Engineering Saga University Honjo Saga 840-8502 JapanDepartment of Energy Science and Engineering Kyushu University Kasuga Fukuoka 816-8580 Japan

The twin impulse wave leads to very complicated flow fields, such as Mach stem, spherical waves, and vortex ring. The twin impulse wave discharged from the exits of the two tubes placed in parallel is investigated to understand the detailed flow physics associated with the twin impulse wave, compared with those in a single impulse wave. In the current study, the merging phenomena and propagation characteristics of the impulse waves are investigated using a shock tube experiment and by numerical computations. The Harten-Yee''s total variation diminishing (TVD) scheme is used to solve the unsteady two-dimensional compressible Euler equations. The Mach number Ms of incident shock wave is changed below 1.5 and the distance between two-parallel tubes, L/d, is changed from 1.2 to 4.0. In the shock tube experiment, the twin impulse waves are visualized by a Schlieren optical system for the purpose of validation of computational work. The results obtained show that on the symmetric axis between two-parallel tubes, the peak pressure produced by the twin impulse waves and its location strongly depend upon the distance between two-parallel tubes, L/d and the incident shock Mach number, Ms. The predicted Schlieren images represent the measured twin-impulse wave with a good accuracy.

关键词： compressible flow unsteady flow impulse wave shock wave shock tube.

Low-temperature crystalline lead-free piezoelectric thin films grown on 2D perovskite nanosheet for flexible electronic device applications

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Nano Research 2019年第10期12卷 2559-2567页

作者： Jong-Hyun Kim Sang Hyo kweon Sahn Nahm KU-KIST Graduate School of Converging Science and Technology Korea University145 Anam-roSeongbuk-guSeoul 02841Republic of Korea Department of Material Science and Engineering Korea University145 Anam-roSeongbuk-guSeoul 02841Republic of Korea Department of Mechanical Engineering Kobe University1-1 Rokkodai-choNadaKobe 657-8501Japan

A monolayer of Sr2Nb3Oio(SNO)is deposited on the Pt/Ti/SiCWSi(Pt?Si)or Pt/Ti/polyimide(Pt-Pl)substrate by using the Langmuir-Blodgett method and employed as a seed-layer for the growth of a crystalline(Nai_xKx)NbO3(NKN)film at 350℃.The crystalline NKN film is grown along the[001]direction on the SNO/Pt-Si(or SNO/Pt-PI)*** to the presence of oxygen vacancies in the SNO seed-layer,the NKN film exhibits low ferroelectric properties and large leakage *** ameliorate these properties,the SNO/Pt-Si substrate is annealed in a 50 Torr oxygen atmosphere at 300℃,which removes the oxygen ***,the NKN film deposited on this substrate exhibits promising electrical properties,namely a dielectric constant of 278,dissipation factor of 1.7%,a piezoelectric 8nstant of 175 pm`V^-1,and a leakage current density of 6.47 x 10^-7 A cm^-2 at-0.2 MV *** electrical properties are obtained from the NKN film grown on the flexible SNO/Pt-PI substrate at 350°***,the NKN films grown on the SNO seed-layer at 350°C can be applied to electronic devices with flexible polymer substrates.

关键词： lead-free piezoelectric thin films low-temperature-deposition process two-dimensional(2D)nanosheet seed-layers polymer substrates

Experimental Investigation on Noise Suppression in Supersonic Jets from Convergent-Divergent Nozzles with Baffles

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Journal of Thermal Science 2003年第3期12卷 260-263,269页

作者： Yoshiaki Miyazato Yong-Hun kweon Toshiyuki Aoki Mitsuharu Masuda Kwon-Hee Lee Heuy-dong Kim Toshiaki Setoguchi Kazuyasu Matsuo Graduate School of Engineering Sciences Kyushu University 6-1 Kasuga-kouen Kasuga Fukuoka816-8580 JapanSchool of Mechanical Engineering Andong National University 388 Songchun-dong AndongKyungbuk 760-749 KoreaGraduate School of Engineering Sciences Kyushu University 6-1 Kasuga-kouen Kasuga Fukuoka816-8580 JapanGraduate School of Engineering Sciences Kyushu University 6-1 Kasuga-kouen Kasuga Fukuoka816-8580 JapanDepartment of Mechanical Engineering Saga University 1 Honjo-machi Saga Saga 840-8502 JapanSchool of Mechanical Engineering Andong National University 388 Songchun-dong AndongKyungbuk 760-749 KoreaDepartment of Mechanical Engineering Saga University 1 Honjo-machi Saga Saga 840-8502 JapanFaculty of Environmental Engineering The University of Kitakyushu 1-1 Hibikino Wakamatsu-kuKitakyushu Fukuoka 808-0135 Japan

The acoustic properties of supersonic jet noise from a convergent-divergent nozzle with a baffle have been studied experimentally over the range of nozzle pressure ratios from 2.0 to 8.0. Acoustic measurements were conducted in a carefully designed anechoic room providing a free-field environment. A new approach for screech noise suppression by a cross-wire is proposed. Schlieren photographs were taken to visualize the shock wave patterns in the supersonic jet with and without the cross-wire. The effects of the baffle and the cross-wire on acoustic properties are discussed. It is shown that the baffle has little effect on the screech frequency for the underexpanded supersonic jet without the cross-wire. Also, the cross-wire introduced in supersonic jets is found to lead to a significant reduction in overall sound pressure level.

关键词：超音速流动噪声控制实验研究收敛-扩散喷管流体力学超音速喷射

Comparison of electrochemical properties of atmospheric pressure plasma coatings for Al_2O_3-3TiO_2 and CoNiCrAlY in sea water

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中国有色金属学会会刊：英文版 2012年第S3期22卷 745-752页

作者： Seong-jong KIM Seong-kweon KIM Jae-cheul PARK Division of Marine Engineering Mokpo Maritime University Department of Electronic IT Media Engineering Institue of TechnologySeoul National University of Science and Technology New Growth Technical Support Team Green and Industrial Technology CenterKorean Register of Shipping

To improve the durability of underwater rotating products,the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating layers by atmospheric pressure plasma spray coating *** evaluating the corrosion resistance of these materials,their applicability to environmentally friendly power generation equipment such as blades of tidal current turbines was *** to the Tafel analysis for micro-areas including the coating layer,the coating/metal interlayer and the base metal,the Al2O3-3TiO2 coating layer and the CoNiCrAlY coating layer show markedly lower corrosion current density than the base *** corrosion current density of the CoNiCrAlY coating layer (9.75316×10-8A/cm2) is about 1.6 times more than that of the Al2O3-3TiO2 coating layer (6.13139×10-8A/cm2).

关键词： Al2O3-3TiO2 coating layer CoNiCrAlY coating layer underwater rotating products marine environment corrosion characteristics atmospheric pressure plasma spray

Improvement of hydrogen embrittlement and stress corrosion cracking by annealing for Al-4.4Mg-0.6Mn alloy

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 17-22页

作者： Seong-Jong KIM Min-Su HAN Seong-kweon KIM Seok-Ki JANG Division of Marine Engineering Mokpo National Maritime University Media Engineering Seoul National University of Technology

With no annealing treatment, cathodic polarization trends in 5083F A1 alloy revealed concentration polarization and activation polarization. However, the annealed specimens have lower current densities at corrosion protection potential compared to the non-annealed specimen. The results of SSRTs conducted in seawater at the applied potential range of-l.8 V to -0.5 V indicated that the maximum tensile strength, elongation, and time-to-fracture had high values at applied potentials of -0.7 to -1.4 V. The maximum tensile strength, elongation, and time-to-f？acture decreased when the potential values were beyond this range in either anodic or cathodic direction. In general, the increased shear lip caused by annealing treatment indicates elongation. Time-to-fracture would likely increase with elongation. Potentials between -0.5 V to -0.6 V were found to be in the region of stress corrosion cracking. The corrosion protection zone was determined to be -0.7 V to -J,4 V because these potential ranges produced good mechanical properties. Potential less than -1.4 V produced a fractured surface with a mixture of dimples （ductile fractures） and a quasi-cleavage pattern resulting from the effects of hydrogen gas.

关键词： annealing 5083F A1-Mg alloy corrosion seawater slow strain rate tests

Development of a variable rate applicator for uniform fertilizer spreading

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International Journal of Agricultural and Biological Engineering 2019年第2期12卷 82-89页

作者： Cheol-woo Han Sang-yoon Lee Young-ki Hong Gi-young kweon Department of Bio-Industrial Machinery Engineering(Institute of Agriculture and Life Science) Gyeongsang National UniversityJinju 52828Korea Department of Agriculture Engineering National Academy of Agricultural ScienceRDAJeonju 54875Korea

Environmental impact and economic concerns have driven a variable rate technology(VRT).Spinner spreaders were mainly used for granular fertilizer application since they are simple in design,inexpensive,and can cover large ***,the spreader was not adequate for VRT because uniformity changes drastically while varying application ***,the purpose of this study was to develop a variable rate applicator with uniform spreading patterns.A commercial spreader was modified with a controller and electric actuators for controlling fertilizer discharge directions and *** was established to determine the optimum discharge direction according to the fertilizer application *** uniformity of spreading patterns in accordance with the spread amount per set unit area was evaluated by the statistical coefficient of variation(CV)lower than 15%is assumed to prevent damage to the *** results showed that CVs were 8%,9%,and 8%,respectively,for a tractor in race track mode(adjacent passes in same direction of travel)at 200 kg/hm^(2),300 kg/hm^(2),and 400 kg/hm^(2).This indicates that the fertilizer was spread uniformly,while the coefficient of variation was 12%at 200 kg/hm^(2) in back and forth mode(adjacent passes in the opposite direction of travel).Overall,the results suggest that the race track mode is suitable for operation of a tractor to ensure uniform spreading of fertilizer when applying at variable *** future goal is to establish a system for automatic variable rate application according to location in connection with soil analysis and geographic information systems.

关键词： variable rate technology fertilizer application uniform spreading spinner granular applicator fertilizer amount control

Cavitation and electrochemical characteristics of thermal spray coating with sealing material

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Transactions of Nonferrous Metals Society of China 2013年第4期23卷 1002-1010页

作者： Seong-Jong KIM Seung-Jun LEE In-Ju KIM Seong-kweon KIM Min-Su HAN Seok-Ki JANG Division of Marine Engineering Mokpo Maritime UniversityHaeyangdaehak-ro 91 Mokpo-Si530-729Korea Korea Institute of Industrial Technology 89 Yangdaegiro-gilIpjang-myeonSeobuk-guCheonan-Si331-822Korea Department of Electronic IT Media Engineering Seoul National University of Science & Technology138 Gongneung-gilNowon-gu Seoul139-743Korea

Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al-14.5%Zn-0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silieon sealing material shows the best anti-cavitation characteristics.

关键词： thermal spray coating sealing material cavitation electrochemical characteristics

Erythropoietin decreases carbon tetrachloride-induced hepatic fibrosis by inhibiting transforming growth factor-beta

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Chinese Medical Journal 2012年第17期125卷 3098-3103页

作者： Soo Young Park Joo Young Lee Won Young Tak Young Oh kweon Mi Suk Lee Department of Internal Medicine Liver Research Institute Graduate School of Medicine Kyungpook National University Daegu Korea

Background In addition to hematopoietic effect, the erythropoietin is known as a multifunctional cytokine with anti-fibrosis and organ-protective activities. The purpose of this study was to evaluate the effect of recombinant human erythropoietin （rhEPO） on hepatic fibrosis and hepatic stellate cells （HSCs）. Methods Carbon tetrachloride （CCI4） induced hepatic fibrosis mice models were used for in vivo study and HSCs line for in vitro study. CCI4 and rhEPO （0,200 or 1000 U/kg） was injected intraperitoneally in BALB/c mice three times a week for 4 weeks. Immunohistochemistry and immunoblotting were performed to evaluate expressions of transforming growth factor-β1 （TGF-β1）, α-smooth muscle actin （α-SMA）, and fibronectin in explanted liver. Immunoblotting of α-SMA, phophorylated Smad-2 and Smad-2/3 was performed in HSCs treated with TGF-β1 and/or rhEPO. Results Expressions of TGF-β1, α-SMA, and fibronectin were increased in CCI4 injected mice livers, but significantly attenuated by co-treatment with CCI4 and rhEPO. Co-treatment of rhEPO markedly suppressed fibrosis in Masson＇s trichrome compared with treatment of only CCI4. TGF-β1 increased phosphorylated α-SMA, Smad-2 expressions in HSCs, which were decreased by rhEPO co-treatment. Conclusions Treatment of rhEPO effectively suppressed fibrosis in CCI4-induced liver fibrosis mice models. Anti-fibrosis effect of rhEPO could be related to inhibition of TGF-β1 induced activation of HSCs.

关键词： fibrosis erythropoietin transforming growth factor-beta hepatic stellate cell animal model