• 제목/요약/키워드: Increase wire size

검색결과 61건 처리시간 0.028초

콘형 배플판을 갖는 Gun식 가스버너의 난류유동장에 대한 슬릿과 스월베인의 역할 (The Role of Slits and Swirl Vanes on the Turbulent Flow Fields in Gun-Type Gas Burner with a Cone-Type Baffle Plate)

  • 김장권;정규조
    • 대한기계학회논문집B
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    • 제27권4호
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    • pp.466-475
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    • 2003
  • The gun-type gas burner adopted in this study is generally composed of eight slits and swirl vanes. Thus, this paper is studied to investigate the effect of slits and swirl vanes on the turbulent flow fields in the horizontal plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 $\ell$/min in the test section of subsonic wind tunnel. The axial mean velocity component in the case of burner model with only swirl vanes shows the characteristic that spreads more remarkably toward the radial direction than axial one, it does, however, directly opposite tendency in the case of burner model with only slits. Consequently. both slits and swirl vanes composing of gun-type gas burner play an important role in decrease of the speed near slits and increase of the flow speed in the central part of a burner because the biggest speed spurted from slits encircles rotational flow by swirl vanes and it drives main flow toward the axial direction. Moreover, the turbulent intensities and turbulent kinetic energy of gun-type gas burner are distributed with a fairly bigger size within X/R<0.6410 than burner models which have only slits or swirl vanes because the rotational flow by swirl vanes and the fast jet flow by slits increase flow mixing, diffusion, and mean velocity gradient effectively.

Hook Wire를 이용한 폐결절의 위치선정 및 생검 (Lung Biopsy after Localization of Pulmonary Nodules with Hook Wire)

  • 김진식;황재준;이송암;이우성;김요한;김준석;지현근;이정근
    • Journal of Chest Surgery
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    • 제43권6호
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    • pp.681-686
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    • 2010
  • 배경: 흉부전산화단층촬영이 보편화되면서 기존의 단순흉부촬영에서는 발견되지 않았던 작은 폐결절이 발견되는 경우가 많아졌다. 이렇게 발견된 폐결절중 크기가 작거나 폐실질 내부에 위치한 결절은 육안 및 촉진으로 확인이 어려운 경우가 많아 생검을 시행하는데 어려움이 따른다. 본원에서는 흉부 전산화단층촬영 유도하에 Hook wire를 사용하여 위치선정을 시행한 후 흉강경하 폐쐐기절제술을 시행하였다. 대상 및 방법: 2006년 12월부터 2010년 6월까지 31명의 환자(남자 17명, 여자 14명)에서 34개의 폐결절을 대상으로 흉부전산화단층촬영 유도 하에 Hook wire를 사용하여 위치선정을 한 후, 흉강경하 폐쐐기절제술을 시행하였다. Hook wire의 이탈 여부, 개흉술 전환 빈도, 위치선정 후 수술 시작까지의 시간, 수술시간, 수술 후 합병증, 대상 병변의 조직학적 진단 등을 분석하였다. 결과: 34예 중 12예는 간유리 병변이었으며 22예는 고형의 폐결절이었다. 병변 크기의 중앙값은 8 mm (범위: 3~23 mm)였으며 병변 깊이의 중앙값은 12.5 mm (범위 1~34 mm)였다. 위치선정 후 마취 시작까지 걸린 시간의 중앙값은 86.5분(41~473분)이었으며, 수술시간의 중앙값은 103분(25~345분)이었다. 1예에서 wire의 흉강 내 이탈이 있었으나 성공적으로 목표 병변을 절제하였다. 4예에서 흉막유착으로 인해 개흉술을 시행하였다. 그러나 목표 병변을 찾지 못해 개흉술로 전환한 예는 없었다. 조직학적 진단에서 전이성 암이 15예로 가장 많았으며, 원발생 폐암 9예, 비특이적 염증소견 3예, 결핵성 염증소견 2예. 림프절 2예, 활동성 결핵 l예, 비정형 샘 증식증 1예 및 정상폐조직 1예로 보고되었다. 결론: 폐실질 내에 위치한 간유리 음영 및 폐결절의 정확한 조직학적 진단을 위해 본원에서는 흉부전산화단층촬영 유도하 Hook wire를 삽입하여 폐결절의 위치를 선정한 후 폐 생검을 시행하였다. 저자들은 이 방법이 정확하면서 최소침습적이고 합병증 발생 및 진료비 상승을 최소화할 수 있는 유용한 술기라고 생각한다.

Hot Wire CVD법에 의한 수소화된 미세결정 실리콘(${\mu} c-Si:H$) 박막 증착 (The Hydrogenated Micro-crystalline Silicon(${\mu} c-Si:H$) Films Deposited by Hot Wire CVD Method)

  • 이정철;송진수;박이준
    • 대한전자공학회논문지SD
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    • 제37권8호
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    • pp.17-27
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    • 2000
  • 열선 CVD(Hot Wire CVD)를 이용해 유리기판에 미세결정 실리콘(${\mu}c$ -Si:H) 박막을 증착시키고, 증착 조건에 따른 막의 특성변화를 관찰하였다. 열선 CVD법에 의한 ${\mu}c$ -Si:H막의 증착률은 조건변화에 따라 0.2nm/sec에서 3.5nm/sec사이의 값을 가졌으며, 기존의 PECVD법에 비해 10배 이상 높은 값이었다. Raman 특성으로부터 ${\mu}c$ -Si:H막은 비정질과 결정질의 두상이 혼합된 상태임을 알 수 있었으며, 평균 결정 립의 크기는 6-10nm, 결정체적분율은 37~63%범위였다. 막의 전도대와 Fermi 준위의 차를 나타내는 전도 활성화에너지(conductivity activation energy)는 30mTorr에서 0.22eV로 나타났으며, 압력에 따라 증가하여 300mTorr에서는 0.68eV의 값을 가졌다. 막의 활성화 에너지 증가는 높은 압력에서 증착된 막의 특성이 진성(intrisic)에 가까움을 의미하며, 이는 압력증가에 따른 암 전도도의 감소특성으로부터 확인할 수 있었다. 또한 이차이온질량분석으로부터 열선온도 1800$^{\circ}C$에서 증착시킨 막의 텅스텐 함유량은 $6{\times}10^{16}atoms/cm^3$임을 알 수 있었다.

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다결정 다이아몬드의 와이어방전가공에 관한 연구 (The Study on the WEDM of Polycrystalline Diamond)

  • 김창호;강재원;오장욱;서재봉
    • 한국기계가공학회지
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    • 제7권3호
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    • pp.67-74
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    • 2008
  • Polycrystalline diamonds(PCD) tools are widely used in machining a large variety of advanced materials. However, the manufacture of PCD tool blanks is not an economical process. The shaping of PCD blanks with conventional machining methods(such a grinding) is long, labor-intensive process. This paper reports experimental investigation of the influence of electrical machining conditions on the metal removal rate of WEDM of PCD. Experimental results show that the longer pulse-on time and the shorter pulse-off time increase the metal removal rate and worsen the surface quality. The smaller grain size of diamond yields the metal removal rate and shows the better surface quality. Higher electrical conductivity of water yields worse surface roughness.

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Spray Characteristics of Electrostatic Pressure-Swirl Nozzle for Burner Application

  • Laryea, Gabriel Nii;No, Soo-Young
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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    • pp.16-23
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    • 2002
  • Electrostatic pressure-swirl nozzle for practical oil burner application has been designed. The charge injection method has been used in this design, where the nozzle consists of a sharp pointed tungsten wire as a charge injector and the nozzle body grounded. The spray characteristics of the nozzles have been investigated by using an insulating liquid, i.e. kerosene without active surface agent. Breakup length of liquid decreased with an increase in applied voltage and injection pressure, while the spray angle increased with an increased in both applied voltage and injection pressure. An empirical equations have been suggested to predict the breakup length for electrostatic pressure-swirl atomizer. The experimental result was within the range of the predicted equations. The SMD decreased between the ranges of 2.8 ${\sim}$ 33% when the conventional nozzle was compared to the electrostatic with -10 kV applied to the electrode at a radial distance from 5 to 20 mm.

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충전제가 습부 탈수 및 종이 물성에 미치는 영향 (Effect of filler loading on the wet end dewatering and paper properties)

  • 원종명;김흥배
    • 펄프종이기술
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    • 제42권4호
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    • pp.33-38
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    • 2010
  • The effects of fillers on the wet end dewatering and paper properties were investigated in order to confirm the possibility that the fillers can be used as a means for saving energy in papermaking process. The performance of GCC, PCC and talcs were evaluated. The dewatering in wire and wet press was improved by the increase of filler addition, but it was observed that the dewatering behavior was depended by the filler characteristics. PCC was superior to other fillers in the bulk, opacity, air permeability and stiffness while the lowest tensile and burst index were obtained. We found that the response on the wet end dewatering and paper properties were affected greatly by the filler characteristics including particle shape and size.

목질계 제지용 충전제 개발을 위한 기초연구(I) (Fundamental Study on Developing Lignocellulosic Fillers for Papermaking(I))

  • 신태기;김철환;정호경;서정민;이영록
    • 펄프종이기술
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    • 제40권2호
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    • pp.8-15
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    • 2008
  • Wastewoods (logging residues) generated in Korea were used to make lignocellulosic fillers for papermaking. Lignocellulosic fillers could play great roles to increase retention efficiency and thus decrease turbidity of white water in papermaking process. In addition, lignocellulosic fillers could be used to improve physical properties of paper through their high affinity to cellulosic fibers, leading to the less use of chemical additives like retention aids. Wastewoods including Pinus densiflora and Quercus variabilis were chemically and mechanically treated for making fine particles passing through 100 mesh wire. The newly generated fillers showed larger particle size distribution than ground calcium carbonates but similar distribution to talc. In particular, pretreatment by hot water was more effective to generate smaller particle size than by alkali treatment. Lignocellulosic particles mixed with ground calcium carbonates under intense hybridizing condition greatly contributed to surface coverage of organic fillers in addition to filling to lumen and pits.

다이아몬드 분말상에 무전해 Ni-B 도금을 위한 계면활성제의 영향 (Effect of Surfactant in Electroless Ni-B Plating for Coating on the Diamond Powder)

  • 양창열;유시영;문환균;이정호;유봉영
    • 한국표면공학회지
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    • 제50권3호
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    • pp.177-182
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    • 2017
  • The properties of electroless Ni-B thin film on diamond powder with different parameters (temperature, pH, surfactant etc.) were studied. The surface morphology, structure and composition distribution of the Ni-B film were observed by field effect scanning electron microscope (FE-SEM), energy-dispersive spectrometer (EDS), X-ray diffraction (XRD) and Auger electron spectroscopy (AES). The growth rate of Ni-B film was increased with increase of bath temperature. The B content in Ni-B film was reduced with increase of bath pH. As a result the structure of Ni-B film was changed from amorphous to crystalline structure. The PVP in solution plays multi-functional roles as a dispersant and a stabilizer. The Ni-B film deposited with adding 0.1 mM-PVP was strongly introduced an amorphous structure with higher B content (25 at.%). Also the crystallite size of Ni-B film was reduced from 12.7 nm to 5.4 nm.

시간경과, 교반 및 분산제 첨가에 따른 물-Al2O3 나노유체 열전도도 변화에 관한 실험적 연구 (An Experimental Study on Thermal Conductivity Change of Water-Al2O3 Nanofluid with the Elapse of Time, Stirring, and Adding Dispersing Agent)

  • 박동욱;박창용
    • 한국생산제조학회지
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    • 제22권3_1spc호
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    • pp.537-543
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    • 2013
  • A water-$Al_2O_3$ nanofluid was manufactured, and its thermal conductivity was measured in this study. The measurement was performed at volumetric concentrations of 0.5%, 1%, 2%, and 3%, and the nanoparticle sizes were 20 nm and 70 nm. Experimental test equipment, using the transient hot wire method, was installed to measure the thermal conductivity of the nanofluid, and the measured results were confirmed by measuring pure water with a measurement error of 0.92% at $20^{\circ}C$. The thermal conductivity enhancement ranged from 4.8% to 13.6% for the 20 nm particle size, and from 3.1% to 8.8% for the 70 nm particle size at a concentration range of 0.5% to 3%. The enhancement increased with a decrease in particle size and an increase in concentration. With the elapse of time after manufacturing the nanofluid, the thermal conductivity enhancement decreased significantly from 5 to 9 h, and this trend was measured under all of the measurement conditions. After 24 h, the enhancement ranged from 1.2% to 3.5% for the 20 nm particles, and from 0.6% to 2.3% for the 70 nm particles. The enhancement trends with the elapse of time were almost identical with and without stirring the nanofluid. SDBS (Sodium Dodecyl Benzene Sulfonate) was added as a dispersing agent, and the decrease in the thermal conductivity enhancement was delayed.

안경테용 Ti 합금 홈선의 고주파유도가열처리에 따른 특성 변화에 관한 연구 (A Study on the Characteristics for High Frequency Induction Heating of Ti Alloy Groove Wire)

  • 박정식;장우영;이정영
    • 한국안광학회지
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    • 제12권3호
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    • pp.55-58
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    • 2007
  • 티타늄과 그 합금은 경량성, 우수한 기계적 성질 그리고 우수한 내식성 때문에 주요한 안경테 소재로 사용되고 있다. 본 연구에서는 티타늄 합금 홈선에 대하여 안경테 브레이징용으로 사용되고 있는 고주파유도가열 장치를 이용한 열처리 시간의 변화에 따른 경도 및 미세조직의 변화에 대하여 조사하였다. ${\beta}-Ti$ 합금은 고주파유도가열처리 시간의 증가에 따라 경도값의 감소가 나타났으며, 이는 열처리 시간의 증가에 따른 결정립의 조대화 때문인 것으로 생각된다. Ti-325 합금의 고주파유도가열처리에서는 2초까지는 경도값이 감소하였으나, 3초에서는 급격히 증가하였다. 이는 2초까지는 결정립의 조대화에 의한 경도값의 감소가 일어나지만, 3초에서는 미세한 ${\alpha}+{\beta}$ 상의 층상조직이 발달하였기 때문으로 판단된다.

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