• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.493-494
• /
• 2006

SU-8 can be implemented as a mask for micro Abrasive Jet Machining (micro-AJM) process [1]. In this paper, we will evaluate the quality of micro grooving result on glass substrate by micro-AJM process which using SU-8 as a mask. It was evaluated on width and edge profile of the micro grooving. The result was having distortion compare with the master film used to pattern the SU-8 mask. The value of distortion with other properties which came along with it, such as depth and surface roughness, can be optimized in order to fabricate micro-channel for micro-fluidic application.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.6
• /
• pp.95-101
• /
• 2011

Micro-abrasive jet machining(${\mu}AJM$) using mask is a fine machining technology which can carve a figure on a material. The mask should have holes exactly same as the required figure. Abrasive particles are jetted into the holes of the mask and it collide with the material. The collision break off small portion of the material. And the ${\mu}AJM$ nozzle should move all over the machining area. However, in general the carving shape is modeled as in a bitmap figure, because it often contains characters. And the mask model is also often modeled from the bitmap image. Therefore, the machining path of the ${\mu}AJM$ also efficient if it can be generated from the bitmap image. This paper suggest an algorithm which can generate ${\mu}AJM$ tool path directly from the bitmap image of the carving figure. And shows some test results and applications.

• Journal of ILASS-Korea
• /
• v.3 no.4
• /
• pp.16-24
• /
• 1998

The fuel injection type, in the gasoline engines of atomization of fuel droplet and its distribution hae influenced directly on the decision of engine performance and harmful emission. In this paper, atomization characteristics of fuel spray is investigated with microscopic visualization system. Particle motion analysis system is used to measure the SMD from fuel spray of air-assisted injector by initial factors such as temperature of ambient air and air-assisted pressure. As air-assist pressure and ambientair temperature increase, the SMD is decreased, and its variation is more stable.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2013.11a
• /
• pp.229-229
• /
• 2013

본 연구에서는 미세 물분무 노즐의 소화성능을 분석하기 위해 유량계수, 방사거리, 방사각도, 그리고 작동압력에 따라 분사되는 물입자 크기를 측정하였다. 이를 위해서 이중 구조의 미세 물분무 노즐 LPN-61과 LPN-63을 제작하였으며, 미분무 소화설비를 구성하여 이중구조 노즐의 형상에 따라서 유동특성을 정량화하였다. 그 결과 LPN-61은 유량계수 5.116, 방사각 $120^{\circ}{\sim}125^{\circ}$로 작동압력이 $4kgf/cm^2$에서 $10kgf/cm^2$까지 증가함에 따라서 SMD는 $127{\mu}m$정도에서 $88{\mu}m$까지 입자 크기가 감소하였으며, LPN-63은 유량계수 5.121, 방사각도 $120^{\circ}{\sim}125^{\circ}$로 동일한 작동압력 범위에서 SMD는 $108{\mu}m$에서 $80{\mu}m$까지 감소하는 것을 확인하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.488-491
• /
• 2005

Abrasive Jet Micromachining (AJM) is a process that uses high pressure air with micron-sized particles to erode a substrate. It has been considered as the most economic and appropriate technique to pattern glass surfaces for the flat panel applications. To accelerate the industrialization of AJM, it is necessary to understand the erosion mechanisms thoroughly. Thus, this paper introduces a new method to model the erosion mechanism in AJM. The model is developed by using the concept of the accumulation of the microdeformation caused by each particle. And this paper proposes the model added the effects of second impact. The developed model is used to simulate the erosion profile, and is compared with the model considered only first impact. It can be concluded that the proposed model predicts the erosion profile more accurately.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.16 no.6
• /
• pp.9-15
• /
• 2012

As a propellant of a high speed underwater vehicle, the hydro-reactive solid metal particles using seawater as a oxidizer maximizes its specific impulse when the solid metal particles and the seawater are uniformly mixed in the combustion chamber. The purpose of this study is to investigate the effects of injector geometry on the particle distribution of similarity point of view. For the purpose of this similarity of the mean velocity and particle number density along the radial direction was measured by Particle Image Velocimetry(PIV).

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1999.05a
• /
• pp.57-57
• /
• 1999

핵연료 펠렛제조공정의 단순화를 위하여 분말을 플라즈마로 용융시킨 후 이를 펠렛몰더에 직접 침적시키는 방법으로 핵연료를 제조하고자 하였다. 침적물의 밀도에 미치는 영향을 관찰하기 위하여 쉬스가스 조성, 플라즈마 동력, 챔버내부압력 및 분말 공급량, 입자크기, 분사관 위치, 분사거리 및 쉬스가스조성 등을 변수로 하였다$^{1)}$ . 실험으로 얻어진 결과는 ANOVA(Analysis of Variance)의 통계적 방법으로 각각의 인자가 밀도에 미치는 영향의 크기뿐만 아니라, 두 가지 이상의 인자가 조합되어 나타나는 영향에 대해서도 분석하였다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.12
• /
• pp.1079-1089
• /
• 2013

The flow characteristics in a solid particle incinerator are investigated numerically for high burning rate of wastes. The studied incinerator employs both a swirl flow used in the furnace of powerplants and a design concept applied to a rocket combustor. As the first step, the non-reactive flow field is analyzed in the incinerator with primary and secondary injectors through which solid fuel and air are injected. The deflection angle of a primary injector, inclination angle of a secondary injector, and gap between the two types of injectors are selected as design parameters. The swirl number is adopted for evaluating the degree of swirl flow and estimated over wide ranges of three parameters. The swirl number increases with deflection angle, but it is affected little by inclination angle. Recirculation zones are formed near the injectors, and their size affects the swirl number. The swirl number decreases with the zonal size of recirculation. From the numerical results, the design points can be found with strong swirl flow.

• Applied Chemistry for Engineering
• /
• v.5 no.5
• /
• pp.836-842
• /
• 1994

The optimum design conditions of gas sparger pipe and the effects of operating variables on $SO_2$ removal efficiency have been examined in Jet Bubbling Reactor. Geometry of gas sparser pipe of Jet Bubbling Reactor is a very important factor to obtain a effective gas-liquid contact. Test results revealed that Reynolds numbers at sparger and slot have to be kept greater than 12,000 identically at a given gas velocity. $SO_2$ removal efficiency was a function of ${\Delta}P$, pH, inlet $SO_2$ concentration and particle size of limestone and was more sensitive to the change of ${\Delta}P$ than to the changes of others. The ${\Delta}P$ of at least 230mmAq must be maintained to acheive the above 90% $SO_2$ removal at pH of 4.0 which is considered as adequate operating pH. Higher $SO_2$ removal efficiency was obtained even at lower pH ranges, which resulted from the complete oxidation of the absorbed $SO_2$ to sulfates by adding air and consequently from the reduction of $SO_2$ equillibrium partial pressure in the gas-liquid interface The 99.5% of the limestone utilization was attained in pH range from 3.0 to 5.0 with regardless to the particle size of limestone employed.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.4
• /
• pp.341-347
• /
• 2011

This work studies the performance of an injector for a monopropellant thruster, comparing a conventional and new injector types. The conventional injector consists of 8 nozzles on a convex surface allowing the jet to be diverged. The new injector, we suggested, is an impinging type with nozzle holes on a concave surface. The fuel streams through the nozzle holes are collide at a point on an axial direction, which allow to atomize the liquid streams and to spray more uniformly along circular direction. The performance of the injectors is investigated by using computational fluid dynamics, particle image velocimetry and high speed camera visualization.