• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.30-34
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• 2009

A Sand blasting technology has been used to address via and trench processing of glass wafer of optic semiconductor packaging. Manufactured sand blast that is controlled by blast nozzle and servomotor so that 8" wafer processing may be available. 10mm sq test device manufactured by Dry Film Resist (DFR) pattern process on 8" glass wafer of $500{\mu}m's$ thickness. Based on particle pressure and the wafer transfer speed, etch rate, mask erosion, and vertical trench slope have been analyzed. Perfect 500 um tooling has been performed at 0.3 MPa pressure and 100 rpm wafer speed. It is particle pressure that influence in processing depth and the transfer speed did not influence.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.4
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• pp.137-141
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• 2004

In this paper, a thermopneumatic PMDS (polydimethlysiloxane) micropump with nozzle/diffuser elements is presented. The micropump is composed of nozzle/diffuser elements as dynamic valves, an actuator consisting of a circular PDMS diaphragm and a Cr/Au heater on a glass substrate. Four PDMS layers are used for fabrication of an actuator chamber, actuator diaphragm by a spin coating process, spacer layer, and nozzle/diffuser by the SU-8 molding process. The radius and thickness of the actuator diaphragm is 2 mm and 30 ${\mu}{\textrm}{m}$, respectively. The length and the conical angle of the nozzle/diffuser elements are 3.5 mm and 20$^{\circ}$, respectively. The actuator diaphragm is driven by the air cavity pressure variation caused by ohmic heating and natural cooling. The flow rate of the micropump in the frequency domain is measured for various duty cycles of the square wave input voltage. When the square wave input voltage of 5 V DC is applied to the heater, the maximum flow rate of the micropump is 44.6 ${mu}ell$/min at 100 Hz with a duty ratio of 80% under the zero pressure difference.

• Journal of the Korean Society of Visualization
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• v.11 no.2
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• pp.34-40
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• 2013

A flow visualization near submerged nozzle of solid rocket motor was conducted by experiments. A numerical simulation was also performed to reveal detailed phenomena. Radial cold flow simulating hot gas was introduced by a porous grain model which was manufactured by perforated steel plates. The grain model was mounted in high-pressure chamber which has quartz glass at the top of the grain model. From the high-speed images, a rotating vortex was observed and the two type of counter-rotating momentums were generated in numerical results. The rotating momentum was generated at the fin-slot grain because of unbalance between high-velocity flow from slots and low-velocity flow from fin-bases. As a result, roll torques can be produced by the rotating vortex tube.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.75-80
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• 2005

The present work was undertaken to numerically analyze the defrosting phenomena of windshield glass. In order to analysis the phase change from frost to water on windshield glass by discharging hot air from a defroster nozzle, the flow and the temperature field of the cabin interior, the heat transfer through the windshield glass, and the phase change of frost should be solve simultaneously. In the present work, the flow field was obtained by solving 3-D incompressible Navier-Stokes equations, and the temperature field was computed from the incompressible energy equation. The phase change process was solved by the enthalpy method. For the code validation, the temperature and the phase change of the driven cavity were calculated. The calculation showed a good agreement with other numerical results. Then, the present code was applied to the defrosting problem of a real automobile, and a good agreement with the experimental data was also obtained.

• 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.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.767-772
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• 2012

Generally, abrasive fluid jet polishing system has been used for polishing of complex shape or freeform surface which has steep local slopes. In the system, abrasive fluid jet is injected through a nozzle at high pressure; however, it is inevitable to lose its coherence as the jet exits a nozzle. This problem causes incorrect polishing results because of unstable and unpredictable workpiece material removal at the impact zone. In order to solve this problem, MR fluid jet polishing method has been developed using a mixture of abrasive and MR fluid which can maintain highly collimated and coherent jet by applied magnetic field. Thus, in this study, an injection nozzle and an electromagnetic module, most important parts in the MR polishing system, were designed and verified by magnetic field and flow analysis. As the results of experiments, it can be confirmed that stable fluid jets for polishing were generated since smooth W-shapes and uniform spot size were observed regardless of standoff distance changes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3074-3079
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• 2009

Efficient energy use becomes necessary since energy consumption has dramatically been increasing due to continuous economic development and population growth. In particular, high efficient vacuum glazing needs to be introduced to buildings where enormous energy loss occurs through windows and has been rarely used yet due to its high price and performance. Therefore, in this study, torch for glass welding was developed with CFD(Computational Fluid Dynamics) and experiments. Torch shape, nozzle diameter, nozzle arrangement etc. were mainly optimized and hydrogen-oxygen mixed gas fuels the torch. Finally, glass welding with the developed torch has been successful, showing that it can be used to develop economic vacuum glazing.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.118-123
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• 2017

It is well known that water jetting is now widely used in the advanced cutting processes of polymers, metals, glass, ceramics, and composite materials because of some advantages, such as heatless and non-contacting cutting different from the laser beam machining. In this paper, we proposed the simulation model of waterjet by lengths and the inner spiral structure of the nozzle. The simulation results show that the outlet velocity of the nozzle is faster than the inlet. Furthermore, we found rapid velocity reduction after passing through the outlet. The nozzle of diameter ${\phi}500$ and length 70mm, shows the optimal fluid width and velocity distribution. Also, the nozzle with inner spiral structure shows a Gaussian distribution of velocity and this model is almost twice as fast as the model without spiral structure, within the effective standoff distance (2.5 mm). In the future, when inserting abrasive material into the waterjet, we plan to analyze the fluid flow and the particle behavior through a simulation model.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1196-1200
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• 2004

Micropump is very useful component in micro/nano fluidics and bioMEMS applications. In this study, a bubble-powered micropump was fabricated and tested. The micropump consists of two-parallel micro line heaters, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 400 ${\mu}m$ in depth pumping chamber. The two-parallel micro line heaters with 20 ${\mu}m-width$ and 200 ${\mu}m-length$ were fabricated to be embedded in the silicon dioxide layer of a wafer which serves as a base plate for the micropump. The pumping chamber, the pair of nozzle-diffuser unit and microchannels including the liquid inlet and outlet port were fabricated by etching through another silicon wafer. A glass wafer (thickness of $525{\pm}15$ ${\mu}m$) having two holes of inlet and outlet ports of liquid serve as upper plate of the pump. Finally the silicon wafer of the base plate, the silicon wafer of pumping chamber and the glass wafer were aligned and bonded (Si-Si bonding and anodic bonding). A sequential photograph of bubble nucleation, growth and collapse was visualized by CCD camera. Clearly liquid flow through the nozzle during the period of bubble growth and slight back flow of liquid at the end of collapsing period can be seen. The mass flow rate was found to be dependent on the duty ratio and the operation frequency. As duty ratio increases, flow rate decreases gradually when the duty ratio exceeds 60%. Also as the operation frequency increases, the flow rate of the micropump decreases slightly.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.6
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• pp.220-224
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• 2016

Anti-reflection (AR) thin films were fabricated on a glass substrate by using an ultrasonic spray. Glycidoxypropyl trimethoxysilane (GPTMS) and tetraethyl orthosilicate (TEOS) were used to synthesize a sol-gel hybrid coating solution. The moving speed of spray nozzle was changed from 15~25 mm/s to control the coating thickness of AR thin film. As the moving speed of spray nozzle increased, the thickness of AR thin film decreased from 138 nm to 86 nm. When the AR thin film was fabricated by nozzle moving speed of 20 mm/s, the refractive index and thickness of AR thin film was measured to be 1.31 and 104 nm, respectively. The average reflectance and transmittance of AR thin film coating glass was measured to be 0.75 % and 94 %, respectively into the visible light range of 380~780 nm.