• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.451-454
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• 2007

This paper presents the pattern characteristic using the electrostatic drop-on-demand ink-jet printing system. In order to achieve the pattern characteristic of electrostatic inkjet printing, the capillary inkjet head system is fabricated using capillary tube, Pt wire and electrode, and is packaged by acrylic board for the accurate alignment between wire and electrode-hole. The applied DC voltage of 1.4 $\sim$ 2.0 kV used for the observation of electrostatic droplet ejection. Electrostatic droplet ejection is directly observed using a high-speed camera. For investigated pattern characteristic, conductive inkjet silver ink used. The higher voltage has a good condition which has micro dripping mode. Also, the droplet size decreases with increasing the supplied DC voltage. This paper shows the pattern which is formed by about 300um. Also, capillary inkjet head system will be applied industrial area comparing conventional electrostatic inkjet head system.

• 한국가시화정보학회지
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• 제9권1호
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• pp.49-54
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• 2011

An investigation has been made of a viscous incompressible flow in a circular cylindrical tank. The flow is driven by the spinning bottom disk of tank together with/without central injection and radial uniform-ejection through the sidewall. Numerical solutions of steady and unsteady flows to 3-dimensional Navier-Stokes equation were obtained for several cases of injection strength. In a moderate flow rate of injection, the mass transfer occurs through the boundary layers but, as the flow rate increases, the inner region far from the container walls takes part in mass transfer.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.658-659
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• 2008

Numerical simulation is performed for a microdroplet deposition on the pre-patterned micro-structure. The liquid-air interface is tracked by level set method improved by incorporating the ghost fluid approach based on a sharp-interface representation. The method is further extended to treat the contact angle condition at an immersed solid surface. The present computation of a patterning process using microdroplet ejection demonstrates that the multiphase characteristics between the liquid-gas-solid phases can be used to overcome the patterning error.

• Journal of Advanced Marine Engineering and Technology
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• 제38권10호
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• pp.1232-1236
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• 2014

Numerical models of fluid dynamics inside the micro actuator chamber and nozzle are presented. The models include ink flow from reservoir, bubble formation and growth, ejection through the nozzle, and dynamics of refill process. Since high tapered nozzle is one of the very important parameters for overall actuator performance design. The effects of variations of nozzle thickness, diameter, and taper angles are simulated and some results are compared with the experimental results. It is found that the ink droplet ejection through the thinner and high tapered nozzle is more steady, fast, and robust.

• 대한기계학회논문집B
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• 제30권10호
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• pp.942-949
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• 2006

A lumped model is proposed to predict liquid ejection characteristics of a thermally driven inkjet print head. The model is based on a two-dimensional heat conduction equation, an empirical pressure-temperature equation and a nonlinear hydraulic flow-pressure equation. It has been simulated through the construction of an equivalent R-C circuit, and subsequently analyzed using SIMULINK and a circuit simulation tool, PLECS. Using the model, heating and cooling characteristics of the head are predicted to be in agreement with the IR temperature measurements. The effects of the head geometry on the drop ejection are also analyzed using the nonlinear hydraulic model. The present model can be used as a design tool for a better design of thermal inkjet print heads.

• International Journal of Aeronautical and Space Sciences
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• 제12권4호
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• pp.385-395
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• 2011

An ejector was developed for man-portable missiles. The ejector can be separated from the missile after the completion of the ejection function even without any additional separation devices. This paper introduces the particular separation mechanism of the ejector and presents the methodology, based on a probabilistic design method, to predict the ejection-and-separation reliability. This approach using Monte Carlo simulation can also be applicable to the reliability prediction of one-shot items suffering from difficulties in estimating or in demonstrating their reliability due to the lack of the number of tests available.

• 전기학회논문지
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• 제58권10호
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• pp.2005-2010
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• 2009

Water droplet ejection characteristics of a point-to-plate airgap, with a wet porous point as a corona electrode, has been investigated. And the water droplet traces, charge, mass and number were measured experimentally. More particles are observed with wet porous point than metal point because the corona-discharging wet porous point can eject a number of water droplets. The water droplets ejected from the positive-corona-discharging wet porous point showed very fine traces as compared with those from the negative-corona-discharging wet porous point. Moreover, the water droplets ejected from the AC-corona-discharging wet porous point showed granular-like larger traces. It was shown that the weak corona discharge can eject smaller water droplets with larger ratio of mass-to-charge than the intense corona discharge.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.433-434
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• 2006

Monosized germanium micro particles are prepared by a newly developed Pulsated Orifice Ejection Method. The obtained particles are categorized into two kinds of the microstructures as refined and coarse ones. The morphological difference is estimated to be determined by the undercooling level during nucleation. Actually, the increase in the temperature of the melt was effective in coarsening the microstructure, because the temperature of the melt intensely relates to the undercooling level. The transition temperature of coarse and refined microstructures is found to be 1300-1350K. Furthermore, a triggered nucleation could improve the crystallinity of the particles in the short separation.

• Tuberculosis and Respiratory Diseases
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• 제50권3호
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• pp.343-352
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• 2001

연구배경 : 만성 폐쇄성 폐질환 기능의 평가를 위해서 여러 가지 비침습적, 침습적 방법이 이용되나 그 정확도나 실용성에 있어서 한계가 있었다. 최근 도플러 심초음파상의 수축기, 이완기 및 박출시간을 조합한 기능지수인 Tei 지수가 우심실기능을 평가하는 유용한 방법으로 알려지고 있어 저자 등은 만성 폐쇄성 폐질환 환자의 Tei 지수를 구하여 우심실 기능을 평가하고 폐기능검사와의 상관관계를 알아보고자 하였다. 대상 및 방법 : 만성 폐쇄성 폐질환 환자 26예와 대조군 10예을 대상으로 간헐파 도플러를 이용하여 도플러 간격을 측정하였다. Tei 지수는 등용성 수축시간(ICT)과 등용성 이완시간(IRT)의 합을 박출시간(ET)으로 나누어 구하였고, PEP, ICT/ET, PEP/ET, IRT/ET를 측정하여 환자군과 대조군을 비교하였다. 폐기능과 Tei 지수의 상관관계를 구하였고, Tei 지수와 다른 도플러 간격의 상관관계를 알아보았다. 결 과 : Tei 지수는 환자군에서 대조군에 비해 유의하게 증가되어 있었고($0.45{\pm}0.17$ vs. $0.27{\pm}0.03$, p<0.01), ICT/ET ($0.32{\pm}0.08$ vs. $0.25{\pm}0.05$, p<0.05), PEP/ET ($0.46{\pm}0.10$ vs. $0.38{\pm}0.06$, p<0.05), IRT/ET ($0.29{\pm}0.16$ vs. $0.15{\pm}0.15$, p&0.05) 등은 대조군보다 증가되어 있었으며 박출시간은 단축되어있었다($255.2{\pm}32.6$ vs. $314.2{\pm}16.5$, p<0.05). 환자군에서 Tei 지수는 1초간 노력성 호기량과 역상관성을 보였고 (r=-0.469), 중증 폐기능 장애가 있는 3기 환자는 1기나 2기 환자에 비해 Tei 지수가 증가되어 있었다. 환자군에서 Tei 지수는 박출시간과 역상관성을 보였고 (r=-0.469), ICT/ET(r=0.453), PEP/ET(r=0.480), IRT(r=0.812), IRT/ET(r=0.896) 는 Tei 지수와 유의한 상관관계가 있었다. 결 론 : Tei 지수는 만성 폐쇄성 폐질환 환자에서 정상 대조군에 비해 유의하게 증가되어 있으며 폐기능 지표와도 유의한 연관성을 보여 만성 폐쇄성 폐질환 환자의 우심실 기능을 평가하는데 유용한 검사법으로 사료된다.

• 한국수산과학회지
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• 제30권1호
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• pp.114-118
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• 1997

국내 유통중인 패류의 토사처리기술개발을 위한 기초 연구의 일환으로 바지락을 중심으로 수온, 염분 및 염화 마그네슘의 농도에 따른 바지락의 토사특성을 검토하였다. 패류의 기본 수계인 해수를 이용하여 토사처리효과를 분석한 바, 꼬막, 피조개 및 동죽은 충분히 토사가 가능한 것으로 나타났으나 바지락은 해수처 리만으로는 불완전한 것으로 평가되었다. 바지락의 토사는 처리수로서 담수를 이용할 경우 이들의 서식환경과 유사한 $2.5\%\;NaCl(pH\;8.0),\;25^{\circ}C$ 조건에서 극대를 나타냈으며 이 조건에 $50\;mM\;MgCl_2$를 첨가시 1.57배의 토사촉진효과를 보였다. 이상의 조건과 해수 및 해수$+20mM\;MgCl_2$ 조건에서 48시간 처리후 토사 배출량을 비교했을 때 해수 $+20mM\;MgCl_2$, 해수, $2.5\%\;NaCl$ (담수)$+50mM\;MgCl_2,\;2.5\%\;NaCl$의 순으로 높게 나타나고 있었으며 이 결과는 관능검사에서도 유효한 것으로 확인되었다. 따라서 바지락의 서식환경과 Mg이온은 바지락의 생물활동과 토사에 깊은 관련이 있는 것으로 추론되었다.