• Title/Summary/Keyword: Nozzle scanning

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Micronization of Ceramic Pigments for Digital Ink-Jet Printing Process (디지털 프린팅 공정을 위한 세라믹 안료의 미립화 거동 분석)

  • Lee, Ji-Hyeon;Hwang, Hae-Jin;Kwon, Jong-Woo;Kim, Jin-Ho;Hwang, Kwang-Taek;Han, Kyu-Sung
    • Korean Journal of Materials Research
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    • v.27 no.2
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    • pp.82-88
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    • 2017
  • Ink-jet printing techniques with ceramic ink, which contains ceramic pigments as colorant, are in increasingly use in the ceramic industry. Generally, ceramic pigments that are produced by conventional method show diameters of several micrometers; these micrometer sized particles in the ink-jet printing process can cause undesirable behavior such as print head nozzle clogging. To prevent this problem, a particle size reduction process is required. In this study, CMYK (cyan, magenta, yellow, black) pigments were synthesized via solid state method. Each pigment particle was milled to submicron size by an attrition mill. The effects of micronizing on the morphology, mechanical property, crystal structure and color property of the CMYK ceramic pigments were investigated by field emission scanning electron microscopy (FE-SEM), particle size analysis (PSA), X-ray diffraction (XRD) and CIE $L^{\ast}a^{\ast}b^{\ast}$.

Fabrication of the Acceleration Sensor Body of Glass by Powder Blasting (미립분사가공을 이용한 유리 소재의 가속도 센서 구조물 성형)

  • Park, Dong-Sam;Kang, Dae-Kyu;Kim, Jeong-Keun
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.2 s.179
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    • pp.146-153
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    • 2006
  • Acceleration sensors have widely been used in the various fields of industry. In recent years, micromachining accelerometers have been developed and commercialized by the micromachining technique or MEMS technique. Typical structure of such sensors consist of a cantilever beam and a vibrating mass fabricated on Si wafers using etching. This study investigates the feasibility of powder blasting technique for microfabrication of sensor structures made of the pyrex glass alternating the existing Si based acceleration sensor. First, as preliminary experiment, effect of blasting pressure, mass flow rate of abrasive and no. of nozzle scanning on erosion depth of pyrex and soda lime glass is studied. Then the optimal blasting conditions are chosen for pyrex sensor. Structure dimensions of designed glass sensor are 2.9mm and 0.7mm for the cantilever beam length and width and 1.7mm for the side of square mass. Mask material is from aluminium sheet of 0.5mm in thickness. Machining results showed that tolerance errors of basic dimensions of glass sensor ranged from 3um in minimum to 20um in maximum. This results imply the powder blasting can be applied for micromachining of glass acceleration sensors alternating the exiting Si based sensors.

Microstructure of the Silk Spinning Nozzles in the Lynx Spider, Oxyopes licenti (Araneae: Oxyopidae)

  • Moon, Myung-Jin
    • Animal cells and systems
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    • v.10 no.2
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    • pp.85-91
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    • 2006
  • The lynx spiders are free wandering spiders with long spines on their legs. They do not build web, but hunt small insects on plants. In spite of the facts that the wandering spiders do not produce webs for prey-catching, they also have silk apparatuses even though the functions are not fully defined. This paper describes the microstructural organization of the silk-spinning nozzles and its silk glands of the lynx spider, Oxyopes licenti, revealed by the field emission scanning electron microscope (FESEM). The silkspinning nozzles of this spider were identified as three groups: ampullate, pyriform and aciniform glands. Each group of silk gland feed silk into one of the three pairs of spinnerets. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another two pair of minor ampullate glands supply the middle spinnerets. In addition, the pyriform glands feed silk into the anterior spinnerets (25-30 pairs in females and 24-40 pairs in males), and the aciniform glands send ductules to the middle (9-12 pairs in females and 7-11 pairs in males) and the posterior spinnerets (16-20 pairs in females and 16-17 pairs in males). Among these, the ampullate one is the most predominate gland in both sexes. However the flagelliform and the aggregate glands which had the functions of cocoon production or adhesive thread production in other webbuilding spiders were not observed at both sexes of this spider.

Experimental Studies on Scramjet Tested in a Freejet Facility

  • Chang, Xinyu;Chen, Lihong;Gu, Hongbin;Yu, Gong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.34-40
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    • 2004
  • Two different type scramjet models with side-wall compression and top-wall compression inlets have been tested in HPTF (Hypersonic Propulsion Test Facility) under the experimental conditions of Mach number 5.8, total temperature 1700K, total pressure 4.5㎫ and mass flow rate 3.5kg/s. The liquid kerosene was used as main fuel for the scramjets. In order to get fast ignition in the combustor, a small amount of hydrogen was used as a pilot. A strut with alternative tail was employed for increasing the compression ratio and for mixing enhancement in the side-wall compression case. Recessed cavities were used as a flameholder for combustion stability. The combustion efficiency was estimated by one dimensional theory. The uniformity of the facility nozzle flow was verified by a scanning pitot rake. The experimental results showed that the kerosene fuel was successfully ignited and stable combustion was achieved for both scramjet models. However the thrusts were still less than the model drags due to the low combustion efficiencies.

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Catalytic Oxidation of CO over Manganese Dioxide Nanoparticles Synthesized Using a High Pressure Homogenizer (고압 균질기를 통해 합성된 이산화망간 나노입자에 의한 일산화탄소의 촉매적 산화)

  • Ji, Sunghwa;Kim, Hyojin
    • Journal of the Korean institute of surface engineering
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    • v.53 no.1
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    • pp.22-28
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    • 2020
  • In this study, manganese dioxide (MnO2) nanoparticles were synthesized from KMnO4 and MnCl2·4H2O without any dispersing agents and oxidant via ultra-high pressure homogenization process. We investigated various physicochemical properties and CO oxidation reactions of the MnO2 nanoparticles as a function of the number of passes at 1,500 bar in a high pressure homogenizer nozzle. The observed X-ray diffraction patterns and scanning electron microscopy images revealed that the synthesized MnO2 nanoparticles had a hexagonal structure and a uniform spherical shape. It was found from the Brunauer-Emmett-Teller measurements that the pore size of the MnO2 nanoparticles ranged from 23.6 to 7.2 nm and their specific surface area ranged from 24 to 208 m2g-1. In particular, it was confirmed from the measurements of CO conversion into CO2 that CO oxidation reaction over the MnO2 nanoparticles exhibited excellent catalytic activity at low temperatures below 100℃.

A Study on Cladding on an Inclined Cylindrical Surface using DED Additive Manufacturing (DED 적층 방식을 활용한 원통면 경사 적층에 관한 연구)

  • Kim, Yeoung-Il
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.5
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    • pp.91-97
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    • 2022
  • The Directed Energy Deposition (DED) is a representative metal additive manufacturing method. Owing to its strong point of repairment, its application is gradually spreading in aerospace applications, power generation, military components, and mold making. 5-axis cladding is needed to repair damage, such as wear and scratches on cylindrical surfaces to circular-shaped parts, including sleeves and liners. Furthermore, the condition of cladding on inclined parts must also be considered to prevent interference between the nozzle and the part. In this study, the effects of changes in scanning speed due to the 5-axis control system and differences from the height of laser beam irradiation due to inclination are evaluated among the items that should be additionally considered in 5-axis cladding compared to 3-axis cladding. Moreover, the trends of the width and height of the clad are identified by different tilting angles via single line cladding. Lastly, cladding methods on cylindrical surfaces at various angles are proposed to enhance the clad quality and post-processing efficacy. These results can be applied with 5-axis cladding on inclined surfaces, including cylindrical surfaces.

Investigating the effects of a range shifter on skin dose in proton therapy

  • Ming Wang;Lei Zhang;Jinxing Zheng;Guodong Li;Wei Dai;Lang Dong
    • Nuclear Engineering and Technology
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    • v.55 no.1
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    • pp.215-221
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    • 2023
  • Proton treatment may deliver a larger dose to a patient's skin than traditional photon therapy, especially when a range shifter (RS) is inserted in the beam path. This study investigated the effects of an RS on skin dose while considering RS with different thicknesses, airgaps and materials. First, the physical model of the scanning nozzle with RS was established in the TOol for PArticle Simulation (TOPAS) code, and the effects of the RS on the skin dose were studied. Second, the variations in the skin dose and isocenter beam size were examined by reducing the air gap. Finally, the effects of different RS materials, such as polymethylmethacrylate (PMMA), Lexan, polyethylene and polystyrene, on the skin dose were analysed. The results demonstrated that the current RS design had a negligible effect on the skin dose, whereas the RS significantly impacted the isocenter beam size. The skin dose was increased considerably when the RS was placed close to the phantom. Moreover, the magnitude of the increase was related to the thickness of the inserted RS. Meanwhile, the results also revealed that the secondary proton primarily contributed to the increased skin dose.

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.

Fabrication of Photocatalytic $TiO_2$ Thin Film Using Aerosol Deposition Method (Aerosol Deposition 법을 이용한 광촉매 $TiO_2$ 박막 제조)

  • Choi Byung-Kyu;Min Seok-Hong;Kim Jong-Oh;Kang Kyong-Tae;Choi Won-Youl
    • Journal of the Microelectronics and Packaging Society
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    • v.11 no.4 s.33
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    • pp.55-59
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    • 2004
  • We fabricates the $TiO_2$ thin film from anatase phase $TiO_2$ powder having good photocatalytic property using aerosol deposition method at room temperature. Aerosol deposition method, which sprays an aerosol powder with ultrasonic velocity and deposits a thin film on substrate at low temperature, has the advantages of low thermal stress and low cost. To fabricate the $TiO_2$ thin film, the aerosol bath pressure and chamber pressure were 500 torr and 0.4 torr, respectively. The difference of aerosol bath pressure and chamber pressure accelerated the $TiO_2$ nano powder to ultrasonic velocity through the nozzle of $0.4 mm{\times}10 mm$ and $TiO_2$ thin film was finally formed. SS mesh with diameter of 50 mm was used as a substrate to apply the $TiO_2$ thin film to water quality purification. The raw powder was dehydrated for the good dispersion of $TiO_2$ powder. To suppress the formation of second particle, the powder was dispersed for 90 min in alcohol bath by ultrasonic treatment and desiccated. The grain size of $1 {\mu}m$ was observed in $TiO_2$ thin film deposited on SUS mesh by scanning electron microscopy (SEM). The anatase phase of $TiO_2$ thin film was also observed by X-ray diffraction (XRD) and the anatase phase of raw powder was nicely maintained after aerosol deposition. The results are applicable to water treatment filter having photocatalytic reaction.

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Evaluation of Alginate Microspheres Prepared by Emulsion and Spray Method for Oral Vaccine Delivery System (유화법과 분무법에 의해 제조된 경구백신용 알긴산 마이크로스피어의 평가)

  • Jiang, Ge;Jee, Ung-Kil;Maeng, Pil-Jae;Hwang, Sung-Joo
    • Journal of Pharmaceutical Investigation
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    • v.31 no.4
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    • pp.241-256
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    • 2001
  • Alginate microspheres, containing fluorescein isothiocyanate-bovine serum albumin (FITC-BSA) or green fluorescent protein (GFP) were prepared and used as a model drug to develop the oral vaccine delivery system. The alginate microspheres were coated with poly-L-lysine or chitosan. Two methods, w/o-emulsion and spray, were used to prepare alginate microspheres. To optimize preparation conditions, effects of several factors on the particle size and particle morphology of microsphere, and loading efficiency of model antigen were investigated. In both preparation methods, the particle size and the loading efficiency were enhanced when the concentration of sodium alginate increased. In the w/o-emulsion preparation method, as the concentration of Span 80 was increased from 0.5% to 2%, the particle size was decreased, but the loading efficiency was increased. The higher the emulsification speed was, the smaller the particle size and loading efficiency were. The concentration of calcium chloride did not show any effect on the particle size and loading efficiency. In the spray preparation method, the particle size was increased as the nozzle pressure $(from\;1\;kgf/m^2\;to\;3\;kgf/m^2)$ and spray rate was raised. Increasing calcium chloride concentration (<7%) decreased the particle size, in contrast to no effect of calcium chloride concentration on the w/o-emulsion preparation method. Alginate microspheres prepared by two methods were different in the particle size and loading efficiency, the particle size of microspheres prepared by the spray method was about $2-6\;{\mu}m$, larger than that prepared by the w/o emulsion method $(about\;2{\mu}m)$, and the loading efficiency was also higher with spray method. Furthermore, drying process for the microspheres prepared by the spray was simpler and easier, compared with the w/o emulsion preparation. Therefore, the spray method was chosen to prepare alginate microspheres for further experiments. Release pattern of FITC-BSA in alginate microspheres was evaluated in simulated intestinal fluid and PBS (phosphate buffered saline). Dissolution rate of FITC-BSA from alginate/chitosan microsphere was lower than that from alginate microsphere and alginate/poly-L-lysine microsphere. By confocal laser scanning microscope, it was revealed that alginate/FITC-poly-L-lysine microspheres were present in close apposition epithelium of the Peyer's patches of rabbits following inoculation into lumen of intestine, which proved that microspheres could be taken up by Peyer's patch. In conclusion, it is suggested that alginate microsphere prepared by spray method, showing a particle size of & $10\;{\mu}m$ and a high loading efficiency, can be used as a model drug for the development of oral vaccine delivery system.

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