• Title, Summary, Keyword: Wet bar

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Photo-assisted GaN wet-chemical Etching using KOH based solution (KOH계열 수용액을 이용한 GaN 박막의 photo-assisted 식각 특성)

  • Lee, Hyoung-Jin;Song, Hong-Ju;Choi, Hong-Goo;Ha, Min-Woo;Roh, Cheong-Hyun;Lee, Jun-Ho;Park, Jung-Ho;Hahn, Cheol-Koo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.339-339
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    • 2010
  • Photo-assisted wet chemical etching of GaN thin film was studied using KOH based solutions. A $2{\mu}m-2{\mu}m$ titanium line-and-space pattern was used as a etching mask. It is found that the etching characteristics of the GaN thin film is strongly dependent on the pattern direction by unisotropic property of KOH based solution. When the pattern was aligned to the [$11\bar{2}0$] directions, ($10\bar{1}n$)-facet is revealed constructing V-shaped sidewalls.

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Influence of connection detailing on the performance of wall-to-wall vertical connections under cyclic loading

  • Hemamalini, S.;Vidjeapriya, R.
    • Advances in concrete construction
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    • v.9 no.5
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    • pp.437-448
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    • 2020
  • In high rise buildings that utilize precast large panel system for construction, the shear wall provides strength and stiffness during earthquakes. The performance of a wall panel system depends mainly on the type of connection used to transfer the forces from one wall element to another wall element. This paper presents an experimental investigation on different types of construction detailing of the precast wall to wall vertical connections under reverse cyclic loading. One of the commonly used connections in India to connect wall to wall panel is the loop bar connection. Hence for this study, three types of wet connections and one type of dry connection namely: Staggered loop bar connection, Equally spaced loop bar connection, U-Hook connection, and Channel connection respectively were used to connect the precast walls. One third scale model of the wall was used for this study. The main objective of the experimental work is to evaluate the performance of the wall to wall connections in terms of hysteretic behaviour, ultimate load carrying capacity, energy dissipation capacity, stiffness degradation, ductility, viscous damping ratio, and crack pattern. All the connections exhibited similar load carrying capacity. The U-Hook connection exhibited higher ductility and energy dissipation when compared to the other three connections.

Wet Oxidation of Phenol with Homogeneous Catalysts (균일촉매를 이용한 페놀의 습식산화)

  • Suh, Il-Soon;Ryu, Sung Hun;Yoon, Wang-Lai
    • Korean Chemical Engineering Research
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    • v.47 no.3
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    • pp.292-302
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    • 2009
  • The wet oxidation of phenol has been investigated at temperatures from 150 to $250^{\circ}C$ and oxygen partial pressures from 25.8 to 75.0 bar with initial pH of 1.0 to 12.0 and initial phenol concentration of 10 g/l. Chemical Oxygen Demand COD has bee measured to estimate the oxidation rate. Reaction intermediates have been identified and their concentration profiles have been determined using liquid chromatography. The destruction rate of phenol have shown the first-order kinetics with respect to phenol and the changes in COD during wet oxidation have been described well with the lumped model. The impact of various homogeneous catalysts, such as $Cu^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Co^{2+}$ and $Ce^{3+}$ ions, on the destruction rate of phenol and COD has also been studied. The homogeneous catalyst of $CuSO_4$ has been found to be the most effective for the destruction of phenol and COD during wet oxidations. The destruction rate of formic acid formed during wet oxidations of phenol have increased as increasing temperature and $CuSO_4$ concentration. The final concentrations of acetic acid which has been formed during wet oxidations and difficult to oxidize have increased with reaction temperature and with decrease in the catalyst load.

The Effect of Pretreatment for Cemented Carbide Substrate Using Wet Blasting

  • Hong, Sung-Pill;Kim, Soo-Hyun;Kang, Jae-Hoon;Yoon, Yeo-Kyun;Kim, Hak-Kyu
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.1102-1103
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    • 2006
  • The pretreatment for substrate was carried out in change of gun pressure of $0.5\sim3.5$ bar using wet blasting. The size of $Al_2O_3$ powder was about $50{\sim}150{\mu}m$. As the results, the surface roughness of cemented carbide substrate was improved with increment of gun pressure of wet blasting. A new surface layer was formed and Co particles were uniformly distributed over the entire surface after pretreatment. The adhesion of the pretreated substrate in same PVD-TiAlN film was improved and in approximately $Ra=90\sim120\;nm$ shown the best adhesion value.

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Electrical Properties of Wet Bars in Water-cooled Generator Stator Windings (흡습된 수냉각 발전기 고정자 권선의 전기적 특성)

  • Kim, Byeong-Rae;Kim, Hee-Dong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.10
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    • pp.817-823
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    • 2012
  • Insulation breakdown of water-cooled generator stator windings occurs frequently due to leakage of cooling water and absorption into the insulation material. Leakage and absorption problems of water-cooled stator windings are often found during regular preventive maintenance. To evaluate cooling water leakage and absorption, diagnostic tests were performed on two water-cooled turbine generators, which have been in service for 13 and 17 years, respectively. The test results of the measured electrical properties such as dissipation factor($tan{\delta}$), capacitance and AC leakage current for water-cooled generator stator windings with wet bars are reported in this paper.

Carbon bead-supported copper-dispersed carbon nanofibers: An efficient catalyst for wet air oxidation of industrial wastewater in a recycle flow reactor

  • Yadav, Ashish;Verma, Nishith
    • Journal of Industrial and Engineering Chemistry
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    • v.67
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    • pp.448-460
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    • 2018
  • Copper nanoparticle-doped and graphitic carbon nanofibers-covered porous carbon beads were used as an efficient catalyst for treating synthetic phenolic water by catalytic wet air oxidation (CWAO) in a packed bed reactor over 10-30 bar and $180-230^{\circ}C$, with air and water flowing co-currently. A mathematical model based on reaction kinetics assuming degradation in both heterogeneous and homogeneous phases was developed to predict reduction in chemical oxygen demand (COD) under a continuous operation with recycle. The catalyst and process also showed complete COD reduction (>99%) without leaching of Cu against a high COD (~120,000 mg/L) containing industrial wastewater.

A Study on the Physical Properties of ATY Produced with Nylon FDY and ROY (Nylon FDY와 ROY로 제조한 ATY의 물성에 관한 연구)

  • Kim Seung Jin;Kim Jae Woo;Hong Sang Gi
    • Textile Coloration and Finishing
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    • v.16 no.6
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    • pp.35-43
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    • 2004
  • This study surveys the physical properties of ATY produced with FDY and POY. ATY is made with 70d Nylon FDY and 80d Nylon POY using AIKI air jet texturing machines, respectively. The processing parameters such as air pressure and yam speed are varied, and air pressure is varied ranging with 8.5bar, l0.5bar and 1l.5bar, and yarn speed is varied ranging with 400m/mim, 450m/mim, and 500m/min. The various physical properties of ATY made by POY and FDY denier, wet shrinkage, dry shrinkage, tensile properties, thermal stress and instability are measured and discussed with air pressure and yam speed. The shrinkage simulation of ATY is performed for analysing the process shrinkage on the dyeing and finishing processes.

Characteristics of ZrO2 Felt Supported Cu/Zn Catalyst for Methanol Steam Reforming (메탄올 수증기개질을 위한 ZrO2 펠트 기반 Cu/Zn 촉매 특성 연구)

  • CHOI, EUNYEONG
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.2
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    • pp.129-136
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    • 2017
  • Characteristics of $ZrO_2$ felt supported Cu/Zn catalysts have been investigated for the production of hydrogen via methanol steam reforming. Cu and Zn in different weight percent were loaded using wet impregnation over $ZrO_2$ felt support. The catalysts were characterized with BET and FE-SEM. The performance of these synthesized catalysts were investigated at SCR=1.5, $GHSV=2000h^{-1}$, temperature=$300{\sim}400^{\circ}C$, and pressure=2.5~19.5 barA. The results showed that the $Cu^{32.5}Zn^{7.5}ZrO_2$ catalyst was most active in terms of methanol conversion and hydrogen production. The methanol conversion in steam reforming of methanol was 84.6% at 19.5 barA and furnace $400^{\circ}C$ over $Cu^{32.5}Zn^{7.5}ZrO_2$ catalyst. The catalysts prepared using $ZrO_2$ felt show higher reactor temperature than the pellet type catalyst at same furnace temperature.

Evaluation of thermal characteristics by cutting environments in high speed ball end-milling (볼엔드밀을 이용한 고속가공에서 가공환경 변화에 따른 열특성 평가)

  • 이채문
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.34-38
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    • 2000
  • The trend of cutting process today goes toward higher precision and higher efficiency. Many thermal/frictional troubles occur in high-speed machining of die and mold steels.In this paper, the thermal characteristics are evaluated in high sped ball end-milling of hardened steel(HRc42). Experimental work is performed on the effect of cutting environments on tool life and cutting temperature. Cutting environments involve dry, wet(20bar), compressed chilly air at -9$^{\circ}C$, compressed chilly air at -35$^{\circ}C$. The measuring technique of cutting temperature using implanted thermocouple is used. The cutting temperature is about 79$0^{\circ}C$, 35$0^{\circ}C$ and 54$0^{\circ}C$ in dry, wet and compressed chilly air at +9$^{\circ}C$, respectively. The tool life for compressed chilly air at -9$^{\circ}C$ is longer than all other cutting environments in experiment.

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A Study on the Development of a Dry PFB Method with High Fire Resistance (고강도콘크리트 내화성능을 확보한 건식화 PFB 공법 개발에 관한 연구)

  • Kim, Woo-Jae;Jung, Sang-Jin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.49-52
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    • 2008
  • The present study was to develop a dry PFB method similar to the existing gypsum board construction method in order to apply the existing wet PFB method that uses fire-resistant adhesive. It was found that the existing wet method can produce concrete compressive strength of 80MPa and fire resistance of 3 hours with 30mm PF boards. The goal of development in this study was fire resistance of 3 hours through dry construction of 15mm fire-resistant boards. 1. Improved PF board was prepared by adding inorganic fiber to existing board and using aggregate with grain size of 3mm or less. Molding was done at temperature higher than that for existing PF board molding. While wet curing is used for existing PF boards, this study used dry curing in order to enhance heat insulation performance. 2. According to the results of fire resistance test, when the dry PF method was applied, the temperature of the main reinforcing bar was 116℃ in 15mm, 103.8℃ in 20mm, and 94℃ in 25mm, and these results satisfied the current standards for fire resistance control presented by the Ministry of Land, Transport and Maritime Affairs. When a 3-hour fire resistance test was performed and the external properties of the specimen were examined, the outermost gypsum board hardly remained and internal PF board maintained its form without thermal strain.

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