• Title/Summary/Keyword: air cut

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Characteristics of Surface Roughness in the High Speed Micro Turning of Aluminum Alloy (알루미늄 합금의 고속 미소 선삭에 있어서 표면거칠기 특성)

  • Seong, Chul-Hyun;Kim, Hyeung-Chul;Kim, Ki-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.7
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    • pp.94-100
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    • 1999
  • This study adopted the ultra precision machining system which was composed of an air bearing spindle, a granite bed, air pad and a linear feeding mechanism. It also applied the cutting experiment on the aluminum alloy. To evaluate the safety of high speed machining, we examined the surface roughness according to the changes of cutting speed and obtained the speed limit. This paper also studied the effect of cutting condition such as feed rates and depths of cut on the surface roughness within the speed limit. This provided practical information regarding ultra precision machining.

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An Experimental Study on the Early Frost Resistance Properties of High-Strength Concrete in Winter Concreting (동절기 고강도콘크리트의 시공에 있어서 초기동해 방지에 관한 실험적 연구)

  • 권영진
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2001.11a
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    • pp.76-81
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    • 2001
  • Recently, the structure is higher and larger, so that the application of high-strength concrete is increased, And as the development of construction skills, it is possible to place during the winter. Concrete work during winter is indispensible to shorten time of completion and cut costs. When concrete work during winter is placed, it has anxiety that concrete freeze at low temperature. As repetition of concrete's freezing cause reduction of durability, it is necessary for mixing to pay attention to air content and W/C ratios. Accordingly, in this study, we estimate the frost resistance by air content and W/C ratios, and development of strength after early-frost damage in the high-strength concrete during the cold weather. In this study, it could be confirmed that factors which were air content, W/C ratios and early curing period, affected on the frost resistance.

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Fault Diagnosis of Screw type Air Compressor (스크루형 공기압축기의 고장진단)

  • Bae Yong-hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.7
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    • pp.1092-1100
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    • 2004
  • This paper describes the application of fault tree technique to analyze of compressor failure. Fault tree analysis technique involves the decomposition of a system into the specific form of fault tree where certain basic events lead to a specified top event which signifies the total failure of the system. In this research. fault trees for failure analysis of screw type air compressor are made. This fault trees are used to obtain minimal cut sets from system failure and system failure rate for the top event occurrence can be calculated. It is Possible to estimate air compressor reliability by using constructed fault trees through compressor failure example. It is Proved that FTA is efficient to investigate the compressor failure modes and diagnose system.

Fabrication and Characteristics of GaAs Power MESFETs Using Air-Bridge Processes (Air-Bridge 공정을 이용한 GaAs Power MESFET의 제작 및 특성 연구)

  • 이일형;김상명;이응호;이진구
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.12
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    • pp.136-141
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    • 1995
  • GaAs power MESFETs with 1 .mu.m gate length and an undoped GaAs surface layer on the doped GaAs channel are fabricated using IR(image reversal) and air-birdge processes. And then We have measured and calculated DC and RF characteristics. We have obtained saturation current 107-500 mA (197-255 mA/mm), maximum linear RF output power 111-518.8 mW (204-270 mW/mm), current gain cut-off frequency 7-10 GHz, maximum unilateral transducer power gain 5.7-12.7, and power added efficiencies 37.9-41.2 % from the devices with gate width 0.45-2.2 mm, at 6 GHz.

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Comparison of Blast Fragmentation Efficiencies from Conventional Bench and Double Air Deck Charge Blast Methods in Limestone Mine (석회석 광산에서 기존 일반발파와 이중분상 Air Deck 발파공법의 비교연구)

  • Kang, Dae-Woo;Hur, Won-Ho;Yang, Kook-Jung;Park, Dong-Chul
    • Explosives and Blasting
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    • v.29 no.2
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    • pp.13-31
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    • 2011
  • Air deck charge blast methods have been applied to improve the fragmentation in open cut bench blastings for mining developments. However, during large scale bench blasting operations, there exist some problems such as boulder productions due to explosive charge concentration. Especially, in case of lime stone mining, when air deck method is applied, there has been unintentionally concentrated on charging because the inside holes are often broken by erosion and decomposition. In this study, compared with general blasting, air deck blasting has been focused in lime stone mining. In other to maximize its efficiency, inside hole was examined by endoscope in advance and deck charge using air tube was applied to the section in which concentration might be taken place. Blasting efficiency, fragmentation, charging reduction rate, and total working hours (from charging to blasting) were the main object for comparing, and as a result, air deck was more efficient then the general blasting in all aspects except total working hours.

Functional and Physical Properties of Weft Knit with Silver Slit Yarn (은 슬릿사 위편성물의 물성 및 기능성)

  • Jeong, Sam-Ho;Park, Jong-Sik;Kwon, Young-Ah
    • Fashion & Textile Research Journal
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    • v.10 no.5
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    • pp.756-761
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    • 2008
  • In this paper, silver slit yarns combined with cotton yarns were used to produce weft knits. The purpose of this study was to investigate the physical properties as well as the functional properties of weft knit with silver slit yarns. The six different weft knit fabrics were made from silver slit yarns varying knit structure and fabric density. One cotton weft knit was also knitted to compare the properties. Weft knits made from silver slit yarns were characterized by excellent antibacterial properties, electric magnetic shielding properties, UV-cut properties, anti-static properties, and air permeability. Although there were significant differences in the physical properties of different knit structure and the fabric density, weft knits with silver slit yarns were seen to have better end use properties and ideal for apparel than the cotton weft knits.

Laser Cutting of Thick Diamond Films Using Low-Power Laser (저 출력 레이저를 이용한 다이아몬드 후막의 절단)

  • 박영준;백영준
    • Journal of the Korean Ceramic Society
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    • v.37 no.2
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    • pp.140-144
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    • 2000
  • Laser cutting of thick diamond films is studied using a low-power(10 W) copper vapor laser. Due to the existence of the saturation depth in laser cutting, thick diamond films are not easily cut by low-power lasers. In this study, we have adopted a low thermalconductivity underlayer of alumina and a heating stage (up to 500$^{\circ}C$ in air) to prevent the laser energy from consuming-out and, in turn, enhance the cutting efficiency. Aspect ratio increases twice fromm 3.5 to 7 when the alumina underlayer used. Adopting a heating stage also increases aspect ratio and more than 10 is obtained at higher temperatures than 400$^{\circ}C$. These results show that thick diamond films can be cut, with low-power lasers, simply by modifying the thermal property of underlayer.

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PULP RFSPONSE TO SELF-CURING RESIN (즉시중합(卽時重合) 레진에 대(對)한 치수반응(齒髓反應))

  • Lim, Sung-Sam
    • Restorative Dentistry and Endodontics
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    • v.2 no.1
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    • pp.7-9
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    • 1976
  • This study was performed to reveal the effect of self-curing acrylic resin to dental pulp when the resin was used directly on the freshly cut dentin. Class V cavity preparations were made on the teeth of dogs with No. 701 carbide bur at a speed of 200,000 rpm and with an air water spray. Petrolatum jelly was coated on the inner surfaces of the cavities. After that, doughs of self-curing acrylic resin were filled in these cavities and before completely set these were removed and cemented with zinc oxide and eugenol cement. The dogs were sacrified between 1 day and 3 weeks at the intervals of one week and routinely processed with hematoxylin and eosin stain for histopathologic interpretation. The results were as followings; 1. The inflammatory changes of the pulp can be seen after the use of self-curing acrylic resin on freshly cut dentin. 2. The inflammatory changes of the pulp were not completely subsided until the end of third experimental week.

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AN EXPERIMENTAL STUDY ON PENETRATION OF DYE IN FILLING MATERIALS (수종(數種) 수복물(修復物)의 색소침투(色素浸透)에 관(關)한 실험적(實驗的) 연구(硏究))

  • Lee, Myung-Chong
    • Restorative Dentistry and Endodontics
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    • v.4 no.1
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    • pp.29-34
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    • 1978
  • The purpose of this study was to measure penetration of dye stuff(5% Methylene blue, Hematoxylin, Crystal violet and Safranin-O) on silicate cement, Adaptic, Hi-pol and unfilled resin. Each filling material was mixed on the mixing pad and the mixed material was inserted with condensation force of 500gr, 1000gr and 2000gr and without condensation force into preformed glass tube (10mm in diameter and 10mm in height). The specimen was stored in the air for 24 hours, then specimen was immersed in various dye solution (5% methylene blue, hematoxin, crystal violet and safranin-O) for different period of time (l hour and 24 hours). These dye-treated specimen was cut horizontally at the middle portion and the dye penetration in cut surface was measured. Following results were obtained. 1. Pentration of various dye was excessive in silicate cement with and without Condensation force. 2. There has been no evidence of dye penetration in unfilled resin. 3. Dye penetration occurced with in 1 hour period and the extending time didn't affect the dye penetration.

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Insulated, Passivated and Adhesively-Promoted Bonding Wire using Al2O3 Nano Coating

  • Soojae Park;Eunmin Cho;Myoungsik Baek;Eulgi Min;Kyujung Choi
    • Journal of the Microelectronics and Packaging Society
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    • v.31 no.2
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    • pp.1-8
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    • 2024
  • Bonding wires are composed of conductive metals of Au, Ag & Cu with excellent electrical conductivities for transmitting power and signals to wafer chips. Wire metals do not provide electrical insulation, adhesion promoter and corrosion passivation. Adhesion between metal wires is extremely weak, which is responsible for wire cut failures during thermal cycling. Organic coating for electrical insulation does not satisfy bondability and manufacturability, and it is complex to apply very thin organic coating on metal wires. Automotive packages require enhanced reliability of packages under harsh conditions. LED and power packages are susceptible to wire cut failures. Contrary to conventional OCB behaviors, forming gas was not required for free air ball formation for both Ag and Pd-coated Cu wires with Al2O3 passivation.