• Title/Summary/Keyword: 노즐 주사

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Deep RIE를 이용하여 제작된 마이크로 노즐 내에서 유체의 거동에 대한 컴퓨터 시뮬레이션 분석

  • Jeong, Gyu-Bong;Song, U-Jin;Cheon, Du-Man;Yeo, Jun-Cheol;An, Seong-Hun;Lee, Seon-Yeong
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2009.05a
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    • pp.37.2-37.2
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    • 2009
  • 다이렉트 프린팅 방식에 대한 수요가 높아지면서 마이크로 노즐에 대한 수요도 높아지고 있다. 마이크로 노즐은 Nano particle deposition system (NPDS)에서 가장 중요한 부분으로 금속이나 세라믹 분말을 음속으로 가속시키는 역할을 한다. 또한 마이크로 노즐은 마이크로 스페이스 셔틀과 주사바늘이 없는 약물 주사 시스템 등의 많은 분야에서 사용 가능하다. 이러한 마이크로 노즐은 대부분 기계적 절삭법을 이용하여 알루미늄으로 만들어져왔다. 하지만 알루미늄으로 만들어진 마이크로 노즐은 경도가 낮아 세라믹 나노 입자를 적층하는 것에 적절치 못하며 사용가능한 수명이 짧다는 단점을 가지고 있다. 또한 가장 큰 단점으로 노즐목을 1mm이하로 제작하는 것이 어렵다는 것이다. 따라서 본 연구에서는 Si wafer를 Deep RIE 방식을 이용하여 3차원적으로 제작하였다. Deep RIE 방식 중 BOSCH process를 이용하였다. 이렇게 만들어진 마이크로 노즐은 다이렉트 프린팅 방식중 하나인 NPDS에 적용하였다. Si wafer로 만들어진 마이크로 노즐이 적용된 NPDS를 이용하여 graphite 분말을 가속하여 적층 실험을 실시하였다 이와 함께 전산 유체 역학(CFD)를 이용하여 마이크로 노즐일 이용한 초음속 가속 가능 여부를 판단하였다. 전산 유체 역학은 유한 요소법을 이용하여 유체의 거동을 시뮬레이션을 통하여 예측하는 것으로 마이크로 노즐 내에서 유체의 흐름을 예상할 수 있다. 실제 실험의 결과와 전산 유체 역학을 이용한 시뮬레이션 결과dml 비교 분석을 실시하였다.

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Effect of Nozzle Scanning in Micro Grooving of Glass by Powder Blasting (Powder Blasting 에 의한 유리의 미세 홈 가공시 노즐 주사횟수의 영향)

  • Kim, Kwang-Hyun;Choi, Jong-Sun;Park, Dong-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1280-1287
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    • 2002
  • The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for brittle materials such as glass, silicon and ceramics, capable of producing micro structures larger than $100{\mu}$ m. This paper describes the performance of powder blasting technique in micro-line grooving of glass and the effect of the number of nozzle scanning on the depth and width of line groove. Experimental results showed that increasing the no. of nozzle scanning resulted in the increase of depth and width in grooves. Increase of width which may cause several problems in the precision machining results from wear of mask film. Therefore, well-controlled masking process is the most important factor for micro machining of glass with accuracy.

Characteristics of Surface Lamination according to Nozzle Position in Liquid Direct Writing SFF (액체 재료 직접주사방식 SFF에서 노즐 위치에 따른 적층 특성)

  • Jung, Hung Jun;Lee, In Hwan;Kim, Ho-Chan;Cho, Hae Yong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.2
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    • pp.41-48
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    • 2014
  • Direct writing(DW) is a method of patterning materials to a substrate directly, without a mask. It can use a variety of materials and be applied to various fields. Among DW systems, the flow-based type, using a syringe pump and nozzle, is simpler than other types. Furthermore, the range of materials is exceptionally wide. In additive processes, a three dimensional structure is made of stacking layer. Each layer is made of several lines. In this regard, good surface roughness of fabricated layers is essential to three dimensional fabrication. The surface roughness of any fabricated layer tends to change with the dispensing pattern. When multiple layers fabricated by a nozzle dispensing system are stacked, control of the nozzle position from the substrate is important in order to avoid interference between the nozzle and the fabricated layer. In this study, a fluid direct writing system for three dimensional structure fabrication was developed. Experimentsto control the position of the nozzle from substrate were conducted in order to examine the characteristics of the material used in this system.

Preparation and Characterization of Polysaccharide-based Nanofiber Using Electrospinning Method (전기방사 방법을 이용한 천연 다당류 나노섬유 제조 및 특성 연구)

  • Kim, Se Jong;Lee, Su Jeong;Woo, Chang Hwa;Nam, Sang Yong
    • Membrane Journal
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    • v.26 no.4
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    • pp.318-327
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    • 2016
  • In this study, alginate/poly(ethylene oxide) (PEO), and chitosan/PEO solution are prepared by dissolving alginate and chitosan into specific solvent for electrospinning. Solutions are poured into 10 mL plastic syringes with a metal nozzle supplied a high voltage power. The solution of alginate and chitosan is controlled by polymer concentration, temperature, relative humidity, applied voltage, distance from nozzle and flow rate of solution. Morphologies of fabricated nanofiber are observed by scanning electron microscopy (SEM). Optimal conditions for electrospinning of alginate nanofiber membrane are 2 wt% of alginate, 2 wt% of PEO at $60^{\circ}C$, 15 cm from the nozzle, $8{\mu}m/min$ flow rate and 20~24 kV. The conditions for elctrospinning of chitosan nanofiber membrane are 2 wt% of chitosan, 2 wt% PEO at $25^{\circ}C$, 15 cm from the nozzle, $8{\mu}m/min$ flow rate and 24 kV. The fabrication conditions of complex nanofiber prepared with chitosan and alginate are 20 cm from the nozzle, $8{\mu}m/min$ flow rate and 26 kV.

Development of a painless injector using high speed laser propulsion and its spin-off to medical industry (고속레이저추진원리를 활용한 무통증 주사기의 개발 및 의료산업으로의 Spin-off)

  • Han, Tae-Hee;Yoh, Jai-Ick
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.326-330
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    • 2010
  • A laser based needle-free liquid drug injection device has been developed. A laser beam is focused inside the liquid contained in the rubber chamber of micro scale. The focused laser beam causes explosive bubble growth, and the sudden volume increase in a sealed chamber drives a microjet of liquid drug through the micronozzle. The exit diameter of a nozzle is 125 ${\mu}m$ and the injected microjet reaches an average velocity of 264 m/s. This device adds the time-varying feature of microjet to the current state of liquid injection for drug delivery.

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Density Profile Evaluation of Needle-punched Carbon/Carbon Composites Nozzle Throat by the Computed Tomography (전산화 단층촬영에 의한 니들펀칭 탄소/탄소 복합재료 노즐 목삽입재의 밀도 분포 평가)

  • Kim Dong-Ryun;Yun Nam-Gyun;Lee Jin-Yong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.10 no.1
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    • pp.44-53
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    • 2006
  • In this study, the non-destructive computed tomography was adopted to observe the density profile of the needle-punched Carbon/Carbon(C/C) composites nozzle throat. The density profile of C/C was evaluated within ${\pm}0.01g/cm^3$ with 98.74% confidence when the correction of the image and high signal-to-noise ratio were achieved by the optimization of the beam hardening, the electrical noise and the scattered X-ray. The density variation of C/C with the computed tomography was in good agreement with the results obtained by the water immersion method and the observation with scanning electron microscope.

Aerosol Deposition 기술을 이용한 $TiO_2$ 코팅 기술

  • Yun, Seok-Gu
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.05a
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    • pp.21.2-21.2
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    • 2011
  • 에어로졸 데포지션(Aerosol deposition) 기술은 상온에서 초음속 유동을 통해 분사된 미세 입자가 기판에 충돌하면서 강력한 결합을 형성하는 방식으로 코팅이 이루어진다. 이 방법은 별도의 소결과정 없이 상온에서도 조밀하고 균일한 박막을 형성할 수 있다. 또한 세라믹, 금속 재질의 다양한 입자를 사용할 수 있을 뿐만 아니라 금속, 유리 기판등에 적용이 가능하다. 본 논문은 이러한 에어로졸 데포지션 기술을 이용하여 광촉매 효과가 뛰어난 $TiO_2$ 입자를 대면적 코팅에 적용가능한 초음속 노즐을 통해 분사하여 ITO기판 위에 박막을 형성하였다. $TiO_2$ 입자의 크기, 기판의 이송 속도와 왕복횟수, 공급 유량 등이 코팅면의 특성과 조성 등에 미치는 영향을 분석하였다. $TiO_2$ 박막층의 형상과 두께는 주사전자현미경(SEM)을 통해 확인하였고, X-ray diffraction (XRD)를 이용하여 코팅 입자와 박막 층의 조성을 각각 확인하였다. 에어로졸 데포지션을 이용한 $TiO_2$ 코팅층은 염료감응형 태양전지(DSSC), 자정작용(self-cleaning), 살균작용(antibacterial effect) 등의 적용분야에 적용 가능할 것으로 판단된다.

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Effect of the Number of Nozzle Scanning in Micro-Line Grooving of Glass by Powder Blasting (Powder Blasting을 이용한 유리의 미세 선형 홈 가공시 노즐 주사 횟수의 영향)

  • 박경호;김광현;최종순;박동삼
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.294-299
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    • 2001
  • The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for various materials, capable of producing micro structures larger than 100 m. This paper describes the performance of powder blasting technique in micro-line grooving of glass and the effect of the number of nozzle scanning on the depth and width of line groove. Experimental results showed that increasing the no. of nozzle scanning resulted in the increase of depth and width in grooves. Increase of width which may cause several problems in the precision machining results from wear of mask film.

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Ablative Mechanism of SiC Coated Carbon/carbon Composites with Ratio of Oxygen to Fuel at Combusion Test (연소시험에서 산소와 연료 비에 따른 탄화규소로 코팅된 탄소/ 탄소 복합재의 삭마 메커니즘)

  • Zhang, Eun-Hee;Kim, Zeong-Baek;Joo, Hyeok-Jong
    • Applied Chemistry for Engineering
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    • v.18 no.3
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    • pp.227-233
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    • 2007
  • Carbon/carbon (C/C) composites as unique materials possess exceptional thermal resistance with light weight, high stiffness, and strength even at high temperature. However, one serious obstacle for application of the C/C composites is their poor oxidation resistance in high temperature oxidizing environments. SiC coating has been employed to protect the composites from oxidation. This study explored combustion characteristics of 4-directional (4D) carbon/carbon composites using liquid fuel rocket engine to investigate ablative motion of the materials. C/C composites were made of coal tar pitch as a matrix precursor, and heat-treated at $2300^{\circ}C$. Throughout repeated densification process, the density of the material reached $1.903g/cm^3$. After machining 4D C/C composites, the nozzle surface was coated by a SiC layer by pack-cementation method to improve oxidation resistance. Erosion characteristics of SiC-coated C/C composites were measured as function of the ratio of oxygen to fuel. The morphological change of the composites after combustion test was investigated using SEM and erosion mechanism also was discussed.

Characteristics and Biocompatibility of Electrospun Nanofibers with Poly(L-lactide-co-ε-caprolactone)/Marine Collagen (전기 방사법을 통해 제조된 Poly(L-lactide-co-ε-caprolactone)/Marine Collagen 나노파이버의 특성 및 세포친화력 평가)

  • Kim, Woo-Jin;Shin, Young-Min;Park, Jong-Seok;Gwon, Hui-Jeong;Kim, Yong-Soo;Shin, Heung-Soo;Nho, Young-Chang;Lim, Youn-Mook;Chong, Moo-Sang
    • Polymer(Korea)
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    • v.36 no.2
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    • pp.124-130
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    • 2012
  • The uniform nanofibers of poly(L-lactide-$co$-${\varepsilon}$-caprolactone) (PLCL) with different contents of marine collagen (MC) were successfully prepared by electrospinning method. The effects of the major parameters in electrospinning process such as tip to target distance (TTD), voltage, nozzle size and flow rate on the average diameter of the electrospun nanofiber were investigated in generating composite nanofiber. The diameter and morphology of the nanofibers were confirmed by a scanning electron microscopy (SEM). Also, we measured a water contact angle to determine the surface wettability of the nanofibers. The average diameter of the nanofibers decreased as the value of TTD, MC contents, and voltages increased in comparison with that of pristine PLCL nanofiber. In contrast, the diameter of the nanofibers increased as the flow rate and inner diameter of nozzle increased in comparison with that of pristine PLCL. In addition, the hydrophilicity of the nanofiber and attachment of MG-63 cells on the sheets increased as incorporated collagen contents increased. Therefore, the marine collagen would be a potential material to enhance cellular interactivity of synthetic materials by mimicking the natural tissue.