• Journal of ILASS-Korea
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• v.17 no.2
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• pp.77-85
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• 2012

The CFD simulation of diesel spray tip penetrations were compared with 0-D simulation for experimental data obtained with common rail injection system. The simulated four injection patterns include single, pilot and split injections. The CFD simulation of the spray penetration over these injection patterns was performed using the KIVA-3V code, which was implemented with both the standard KIVA spray and original gas jet sub-models. 0-D simulation of the spray tip penetration with time-varying injection profiles was formulated based on the effective injection velocity concept as an extension of steady gas jet theory. Both the CFD simulation of the spray tip penetration with the standard KIVA spray model and 0-D simulation matched better with the experimental data than the results of the gas jet model for the entire fuel injection patterns.

• Fire Science and Engineering
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• v.29 no.3
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• pp.43-47
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• 2015

Water mist was sprayed on small compartment areas filled with smoke that formed from two different combustibles. The water-mist injection pressure and time were varied, and changes in the light extinction coefficient were measured over time. The smoke removal effect was analyzed with a light sensing smoke meter in different experimental conditions. Using the meter, the changes in smoke density were converted to changes in DC voltage over time to obtain the changes in the light extinction coefficient. The water mist was more effective in eliminating the smoke formed from glowing compared to flaming combustion. The smoke removal effect was significantly better with greater injection pressure and injection time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.10
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• pp.868-874
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• 2015

Thrust variation is an essential parameter in a space mission such as landing on an atmosphereless planet or docking a spacecraft. In order to achieve the thrust variation control, using throttleable injector is a representative and general method. A dual-manifold injector, one of throttleable injectors, was used to control mass flow rate. Five kinds of injectors were designed and investigated in order to compare the spray characteristics of the dual-manifold injector with various tangential entries. Spray angles and patterns were measured to determine external flow characteristics and film thicknesses were measured in order to investigate the internal flow patterns.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.221-222
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.913-914
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• 2009

• Particle and aerosol research
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• v.13 no.3
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• pp.111-118
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• 2017

Electrohydrodynamic (EHD) printing with the aid of strong electric fields can generate and pattern droplets that are smaller than droplets by other printing technologies. Conventional EHD printing has created two-dimensional (2D) patterns by moving its nozzle or a substrate in X and Y directions. In this study, we aimed to develop an EHD system that can create 2D patterns using a multielectrode array (MEA) without moving a nozzle or substrate. In particular, printing ink mixtures of biodegradable polymers and model dyes was patterned on a thin film made of another biodegradable polymer. Without movement of a nozzle and substrate, stable 2D patterning of minimum $6{\mu}m$ size over a range of about 1 mm away from the nozzle position was achieved by MEA control only. We also demonstrated the possibility of denser 2D pattering of the ink mixtures by moving a target substrate relative to MEA position.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.115-120
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• 2010

The reduction rate of fuel consumption by showing the fuel injection data for driver was measured in this study. The fuel injection data are composed of injection period, real time fuel economy and average fuel economy. The fuel consumption was measured by processing the voltage signal of injector and driven distance by GPS sensor. The fuel consumption was reduced by driving more carefully, i.e driving more steady without sudden acceleration and deceleration watching these fuel injection data. The reduction rate was up to 37% and the rate increased as the driver is customed to this driving pattern.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.53-57
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• 2007

고속회전의 원심력으로 연료를 공급하고 액체연료의 미립화를 초래하는 회전연료분무장치에 대한 분무특성 시험연구를 수행하였다. 특정한 공간상에 존재하는 액적의 특성을 이해하고자 고속회전 연료분사시스템을 설계 제작하였다. 시험장치는 고속으로 회전하는 Spindle, 회전연료노즐, 가압식 물탱크, 아크릴 케이스로 구성하였다. 액적의 크기와 속도를 측정하기 위해 PDPA(Phase Doppler Particle Analyzer)시스템을 사용하였고, ND-Yag Laser를 사용하여 분무를 가시화 하였다. 시험결과 고속회전 연료분사시스템의 분무특성을 확인할 수 있었고, 회전속도는 액적 크기, 속도, 분무각 및 분무패턴 등의 분무특성에 주요한 영향을 미치는 것으로 확인되었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.225-227
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• 2011

The geometrically sub-scaled wall-injection test model was employed to visualize interactions of internal flow of a solid rocket motor equipped fin/slot grain and submerged nozzle. Symmetric vortex and circumferential flow patterns were visualized.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.64.2-64.2
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• 2012

전자산업에서 소자를 제작하는 핵심공정으로써, 패턴을 형성하는 방식은 식각 마스크를 통해 이루어진다. 공정 순서는 원하는 물질을 증착한 후 사진공정 (photolithograpy)을 통하여 원하는 패턴의 감광제 식각마스크 (etch mask)를 형성하게 된다. 이후, 습식식각이나 건식식각을 통하여 물질의 불필요한 부분을 제거한 후 최종적으로 감광제 식각마스크를 제거하여 원하는 물질의 패턴을 얻게 된다. 최근에 소개된 잉크젯 프린팅 기술 (inkjet printing technology)은 나노 잉크를 이용하여 사진공정과 식각공정을 이용하지 않고, 직접 나노잉크를 분사하여 패턴을 형성하는 방법으로, 패터닝 공정을 단순화 시킬 수 있을 뿐만 아니라 각종 전자 산업의 환경오염물을 획기적으로 줄일 수 있는 친환경기술이다. 특히, OLED, O-TFT, RF-ID, PCB 분야 등 다양한 전자산업분야의 제조기술로서 응용하고자, 전도성 폴리머나 실버 (silver) 나노파티클 잉크를 이용한 전도성 라인 패터닝 (line patterning)에 관한 연구가 활발히 진행되고 있다. 본 강연에서는 친환경 생산공정기술 측면에서의 잉크젯기술을 분석하고, 기술의 구성요소, 응용분야, 기술 동향에 관해서 소개하고, 또한 현재 한국생산기술연구원에 진행하고 있는 잉크젯 프린팅 기술 기반의 인쇄전자 분야에 관한 내용을 소개한다.