• Title/Summary/Keyword: Mesh type

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Evaluation of Turbulent Models on the Swirling Flow of a Gun-Type Gas Burner According to the Mesh Size (격자크기에 따른 Gun식 가스버너의 스월유동에 대한 난류모델평가)

  • Kim, Jang-Kweon;Oh, Seok-Hyung
    • Journal of Power System Engineering
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    • v.18 no.3
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    • pp.59-65
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    • 2014
  • The computational fluid dynamics was carried out to evaluate turbulent models on the swirling flow of a gun-type gas burner(GTGB) according to the mesh size. The commercial SC/Tetra software was used for a steady-state, incompressible and three-dimensional numerical analysis. In consequence, the velocity magnitude from the exit of a GTGB and the flowrate predicted by the turbulent models of MP k-${\varepsilon}$, Realizable k-${\varepsilon}$ and RNG k-${\varepsilon}$ agree with the results measured by an experiment very well. Moreover, the turbulent kinetic energy predicted by the turbulent model of standard k-${\varepsilon}$ with mesh type C only agrees with the experimental result very well along the radial distance. On the other hand, the detailed prediction of the information of swirling flow field near the exit of a GTGB at least needs a CFD analysis using a fairly large-sized mesh such as a mesh type C.

Characteristics of Amorphous Si Films Fabricated by Mesh-type PECVD and Their Crystallization Behavior Using Excimer Laser (Mesh-type PECVD 방법으로 제조된 비정질 Si박막의 특성 및 레이저 결정화)

  • Han Sang-Yong;Choi Jae-Sik;Kim Yong-Su;Park Sung-Gye;Ro Jae-Sang;Kim Hyoung-June
    • Journal of the Korean Electrochemical Society
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    • v.3 no.1
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    • pp.19-24
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    • 2000
  • It is increasingly necessary to use poly-Si n's as high resolution and integration of Tn for LCD. Excimer Laser Crystallization (ELC) of a-Si is mainly used as a low temperature process. But the ELC method for the fabrication of poly-Si has the eruption problems associated with hydrogen in the a-Si film. So we need a dehydro-genation process additionally. Hydrogen in a-Si film can degrade the quality of poly-Si film and electrical properties of device due to the hydrogen eruption and voids which occur during the excimer laser annealing. In this study, we propose mesh-type PECVD as the a-Si film deposition method for achieving the low concentration hydrogen. Mesh-type PECVD was found to reduce the hydrogen content substantially. We could obtain a as-deposited a-Si film with hydrogen contents less than $1\%$ at $300^{\circ}C$. We also investigated the behavior by XeCl excimer laser annealing of a-Si fabricated by mesh-type PECVB. As a result, we were able to confirm the broad process window in contrast to the narrow process range typically obtained in ELC. Hydrogen eruption was not observed in poly-Si films after ELC These results suggests that mesh-type PECVD is a viable method to achieve the low hydrogen content a-Si and improve the process windows for ELC.

사각형강목의 끝자루를 이용한 트롤어구의 어획선택성 연구 ( I ) - 사각형강목의 어획선택성 - ( Studies on the Selectivity of the Trawl Net With the Square Mesh Cod-End ( 1 ) - Selectivity of the Square Mesh Cod-End - )

  • Lee, Ju-Hee;Kim, Sam-Kon;Kim, Jin-Kun
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.30 no.3
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    • pp.161-171
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    • 1994
  • Mesh selection analysis for the trawl net were carried out at the Southern Korean Sea and the East China Sea during the 1992-1994 years by the training ship Seabada of the National Fisheries University of Pusan, using A type (51.2mm), B type (70.2mm), C type (77.6mm), D type (88.0mm) square mesh cod-ends. The fishing trials were made using bottom trawl of the trouser type cod-end with cover net. Selection curves and selection parameters were calculated by a logistic model for Sphyraena pinguis, Pampus argenteus, Trachurus japonicus, Pagrus major, Callanthias japonicus, Trichiurus lepturus. The results obtained are summarized as follows: 1. Red barracuda : Selection range and fifty percent selection length in the A type was 115.8mm, 292.8mm, respectively. 2. Harvest fish : Each selection range and fifty percent selection length in the B. C. and D type was 37.7mm, 113.8mm : 40.1mm, 131.7mm and 64.8mm, 148.6mm, respectively. Selection parameters of master curve were : slope, 3.81 : intercept, -6.4. Optimum mesh size was 89.3mm. 3. Horse mackerel : Each selection range and fifty percent selection length in the A, B, C and D type was 43.0mm, 148.3mm : 60.7mm, 183.2mm, 214.5mm and 91.4mm, 254.9mm, respectively. Selection parameters of master curve were : slope 2.30 : intercept, -6.4. Optimum mesh size was 66.8mm. 4. Red seabrem : Selection range and fifty percent selection length in the D type was 42.7mm, 203.4mm, respectively. 5. Yellowsail red bass : Selection range and fifty percent selection length in the A type was 84.0mm, 110.6mm, respectively. 6. Hair tail : Each selection range and fifty percent selection length in the A, B and C type was 59.7mm, 176.0mm : 100.9mm, 250.7mm and 178.6mm, 307.0mm, respectively. Selection parameters of master curve were : slope, 1.54 : intercept, -5.4. Optimum mesh size was 57.5mm.

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The Characteristics of a Superposed Discharge Type Ozonizer with variation of Mesh (Mesh 형 전극의 조밀도 변화에 따른 중첩방전형 오존발생기의 특성)

  • Song, Hyun-Jig;Lee, Dong-Heon;Kim, Tae-Ju;Lee, Kwang-Sik;Chun, Byung-Jun;Ha, Jang-Ho
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1834-1836
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    • 2003
  • In this paper, a superposed discharge type ozonizer(SDO) has been designed and manufactured. SDO is equipped with three electrodes(central, internal and external electrodes), and it is composed of two gaps. Ozone is generated by overlapping silent discharge, which is respectively came from two gaps. At this time, Internal electrode consists of a mesh type. This paper describes the discharge and ozone generation characteristics of SDO with variation of mesh and discharge wattage.

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Effective Ionic Wind Generation Utilizing a Cylindrical Corona Discharge Electrode (금속관형 코로나 방전극을 적용한 효과적인 이온풍 발생)

  • Jung, Jae-Seung;Moon, Jae-Duk
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.3
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    • pp.599-603
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    • 2010
  • A point-mesh type corona system has been well used as a ionic wind blower. However this type corona system suffers from its lower ionic wind generation, because of its lower on-set and breakdown voltages of its very sharp needle point corona electrode. This means that the point corona electrode must act both as an effective ion-generator and a very higher electric field producer in the discharge airgap in order to generate higher ionic wind velocity. In this paper, a cylinder-mesh type discharge system as a ionic wind generator is proposed and investigated. The cylindrical corona electrode can produce many ions from its sharpened edge, and the corona on-set and breakdown voltages are very higher than those of the needle point corona electrode. As a result, this type cylindrical corona electrode might generate a higher ionic wind than the needle point corona electrode.

Characteristics of a Flexible Transparent Electrode based on a Silver Nanowire-polymer Composite Material with a Mesh Pattern Formed without Lithography (리소그래피 없이 제작된 그물망 구조의 은나노와이어-고분자화합물 복합소재 기반 유연 투명전극의 특성)

  • Park, Tae Gon;Park, Jong Seol;Park, Jin Seok
    • Journal of the Semiconductor & Display Technology
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    • v.19 no.4
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    • pp.11-17
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    • 2020
  • In this study, a new method for fabricating flexible transparent electrodes based on silver nanowire-polymer (AgNW-PEDOT:PSS) composite materials having a mesh pattern formed by a solution-based process without lithography was proposed. By optimizing conditions such as the amount of ultraviolet (UV) photosensitizer injected into the suspension of AgNW and PEDOT:PSS, UV exposure time, and deionized (DI) washing time, a clear and uniform mesh pattern was obtained. For the fabricated AgNW-PEDOT:PSS-based mesh-type electrodes, characteristics such as electrical sheet resistance, light transmittance, haze, and bending flexibility were analyzed according to the mixing ratio of AgNW and PEDOT:PSS included in the suspension. The fabricated mesh electrodes typically exhibited a low electrical sheet resistance of less than 20 Ω/sq while maintaining a high transmittance of 80% or more. In addition, it was confirmed from the results of analyzing the effect of PEDOT:PSS on the characteristics of the mesh-type AgNW-PEDOT electrode that the optical visibility was greatly enhanced by reducing the surface roughness and haze, and the bending flexibility was remarkably improved.

The Properties of Low Hydrogen Content α-Si Thin Film Using DC-bias Enhanced or Addition of H2Gas in Mesh-type PECVD System (Mesh-type PECVD를 이용한 DC-bias인가 및 수소가스 첨가에 따른 저수소화 비정질 실리콘 박막에 관한 연구)

  • Ryu, Se-Won;Gwon, Do-Hyeon;Park, Seong-Gye;Nam, Seung-Ui;Kim, Hyeong-Jun
    • Korean Journal of Materials Research
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    • v.12 no.4
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    • pp.235-239
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    • 2002
  • In this study mesh-type PECVD system was suggested to minimize the hydrogen concentration. The main structural difference between the triode system and a conventional system is that, a third electrode, a mesh, is inserted between the powered and the ground electrode. We investigated several conditions to compare with conventional PECVD. The main effect of mesh was to minimize the substrate damage by ion bombardment and to enhance the surface reaction to induce hydrogen desorption. It was also found that hydrogen concentration decreased but deposition rate increased as increasing applied bias. Applied DC-bia s enhanced sputtering process. Intense ion bombardment causes the weakly bonded hydrogen or hydrogen-containing species to leave the growing film and increased adatom mobility. Furthermore, addition of hydrogen gas enhance the surface diffusion of adatom.

Rehabilitation of exterior RC beam-column connections using epoxy resin injection and galvanized steel wire mesh

  • Marthong, Comingstarful
    • Earthquakes and Structures
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    • v.16 no.3
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    • pp.253-263
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    • 2019
  • The efficacy of a galvanized steel wire mesh (GSWM) as an alternative material for the rehabilitation of RC beam-column connections damaged due to reversed cyclic loading was investigated. The repair mainly uses epoxy resin infused under pressure into the damaged zone and then confined using three types of locally available GSWM mesh. The mesh types used herein are (a) Weave type square mesh with 2mm grid opening (GWSM-1) (b) Twisted wire mesh with hexagonal opening of 15 mm (GSWM-2) and (c) welded wire mesh with square opening of 25 mm (GSWM-3). A reduced scale RC beam-column connection detailed as per ductile detailing codes of Indian Standard was considered for the experimental investigation. The rehabilitated specimens were also subjected to similar cyclic displacement. Important parameters related to seismic capacity such as strength, stiffness degradation, energy dissipation, and ductility were evaluated. The rehabilitated connections exhibited equal or better performance and hence the adopted rehabilitation strategies could be considered as satisfactory. Confinement of damaged region using GSWM-1 significantly enhanced the seismic capacity of the connections.

Influences of Mesh Shapes and Interspacings on Ozone Generation Characteristics (그물방전극 형상과 방전공격이 오존생에 미치는 영향)

  • Park, Seung-Lok;Lee, Jae-Chan;Moon, Jae-Duk;Jung, Sung-Jin
    • Proceedings of the KIEE Conference
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    • 2000.07e
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    • pp.29-32
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    • 2000
  • Ozone has been widely applied to many industrial fields because of its strong oxidation effects. Therefore, the studies have been progressed for the effective and high concentration of one generation. The silent or surface discharge have been mainly used for high concentration ozone generation until now. But these two types of ozone generators have shortcomings to be improved. In this study, the ozone generator which improved the shortcomings of above two type of ozone generators was proposed and manufactured for high concentration ozone generation. And the proposed ozone generator could generate the surface and barrier discharge simultaneously. For this purpose, a mesh type discharge electrodes were proposed and the experiments were fulfilled as a function of the widths and spacings of mesh electrodes and gap spacings between the dielectric barrier and mesh electrode. When the width of mesh electrode[WM] and spacing of mesh electrode[SM] are 0.3[mm] and 0.8[mm] respectively, the maximum ozone concentration of 2.96[vol%] was obtained at 5.6[kV], 830[mA], gap spacing (S)=0.65[mm].

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