• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.85-90
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• 1998

A 1 4 polymeric optical power divider based on the multimode interference effect is designed and fabricated. The two dimensional finite difference beam propagation method has been utilized in designing the device. Polymers used for the core layer and the cladding layer are Cyclotene-3022 and UV-15, respectively. The device is fabricated by the reactive ion etching method. The splitting ratio of the fabricated device is 0.93 : 1.00 : 0.93 : 0.90 for TE mode and 0.84 : 0.94 : 1.00 : 0.83 for TM mode. The advantages of this device are small size and low polarization-dependence.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.11 s.188
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• pp.116-125
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• 2006

MEMS and LIGA technologies have been used for fabricating microstructures, but their shape is not 3D because of difficulty for preparation of many masks. To fabricate 3D microstructures, microstereolithography technology based on Digital Micromirror Device($DMD^{TM}$) was introduced. It has no need of masks and is capable of fabricating high aspect ratio microstructures. In this technology, STL file is the standard format as the same of conventional rapid prototyping system, and 3D parts are fabricated by layer-by-layer according to 2D section sliced from STL file. The UV light source is illuminated to DMD which makes bitmap images of 2D section, and they are transferred and focused on resin surface. In this paper, we addressed optical design of microstereolithography system in consideration of light path according to DMD operation and image-forming on the resin surface using optical design program. To verify the performance of implemented microstereolithography system, 3D microstructures with complexity and high aspect ratio were fabricated.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.459-464
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• 2013

The purpose of a micro-mixing device is to enhance the mixing by increasing the diffusion effect between different types of flows. There have been many attempts to actively or passively increase mixing. However, those studies were limited to lab-scale experiments because the production of devices requires a series of processes, time, cost, and the mixing quality itself. For this reason, this study attempted to develop a quick and simple process for micro-mixing device fabrication by using conventional machining and bonding processes and applying ultrasonic waves from the outside of the mixing device. The mixing quality was quantified by using the mixing index, and the results showed that the proposed system increases the mixing from ~33% to ~10% with respect to the flow rates.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1460-1462
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• 1994

BiCMOS is the newly developed technology that integrates both CMOS and bipolar structures on the same integrated circuit. Improved performance can be obtained from combining the advantages of high density and low power in CMOS with the speed and current capibility advantages by bipolar. However, the major drawbacks to BiCMOS are high cost, long fabrication time and difficulty of merging CMOS with bipolar without degrading of device Performance because CMOS and bipolar share same process step. In this paper, N-Well CMOS oriented BiCMOS process and optimization of device performance are studied when N-Well links CMOS with bipolar process step by 2D process and 3D Device simulation. From the simulation, Constriction of linking process step has been understood and provided to give the method of choosing BiCMOS for various analog design request.

• Journal of the Korean Magnetics Society
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• v.21 no.1
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• pp.32-36
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• 2011

We fabricated a sensor for measuring the water level and water temperature using GMR-SV (giant magnetoresistance-spin valve) device, simultaneously. It could be applied to the medical cooling system of the potassium titanylphosphate KTP) laser system for the therapy of a benign prostatic hyperplasia. The middle point of GMR-SV device was set to the near position of a high magnetic sensitivity with 2.8%/Oe. The sensitivity for the water level and water temperature of the fabricated sensor were $400\;m{\Omega}/mm$ and $100\;m{\Omega}/^{\circ}C$, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.175-184
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• 2001

In this study, the improved throughput and stability in device fabrication could be obtained by applying CMP process to STi structue in 0.18 um semiconductor device. To employ the CMP process in STI structure, the Reverse Moat Process used to be added after STI Fill, as a result, the process became more complex and the defect were seriously increased than they had been,. Removal rate of each thin film in STI CMP was not uniform, so, the device must have been affected. That is, in case of excessive CMP, the damage on the active area was occurred, and in the case of insufficient CMP nitride remaining was happened on that area. Both of them deteriorated device characteristics. As a solution to these problems, the development of slurry having high removal rate and high oxide to nitride selectivity has been studied. The process using this slurry afford low defect levels, improved yield, and a simplified process flow. In this study, we evaluated the 'High Selectivity Slurry' to do a global planarization without reverse moat step, and also we evaluated EPD(Eend Point Detection) system with which 'in-situ end point detection' is possible.

• Journal of Pharmaceutical Investigation
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• v.36 no.4
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• pp.263-269
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• 2006

Deficiencies in the early ADMET(absorption, distribution, metabolism, elimination and toxicity) information on drug candidate extract a significant economic penalty on pharmaceutical firms. Microscale cell culture analogue-microscale gastrointestinal(${\mu}CCA-{\mu}GI$) device using Caco 2, L2 and HEp G2/C3A cells, which mimic metabolic process after absorption occurring in humans was used to investigate the toxicity of the model chemical, acetaminophen(AAP). The toxicity of acetaminophen determined after induction of CYP 1A1/2 in Caco 2 cells was not significant. In a coculture system, although no significant reduction in viability of HEp G2/C3A and L2 cells was found, approximately 5 fold increase in the CYP 1A1/2 activity was observed. These results appear to be related to organ-organ interaction. The oral administration of a drug requires addition of the absorption process through small intestine to the current ${\mu}CCA$ device. Therefore, a perfusion coculture system was employed for the evaluation of the absolution across the small intestine and resulting toxicity in the liver and lung. This system give comprehensive and physiologic information on oral uptake and resulting toxicity as in the body. The current ${\mu}CCA$ device can be used to demonstrate the toxic effect due to organ to organ interaction after oral administration,

• Korean Journal of Materials Research
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• v.17 no.4
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• pp.185-191
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• 2007

The purpose of this study is to evaluate the thin fihn dielectric made of hybrid sol, which consist of barium titanate powder, polymeric sol and other polymers. This sol will be used dielectric applied to small, thin electric passive components such as MLCC(Multi Layer Ceramic Condenser), resister, inductor. This sol is composed of mixed fine barium titanate powder and polymeric sol including Ba, Ti-precursor, solvent, chelating agent, chemical reaction catalyst, the additive sols to improve fired densification and temperature reliability. First at all, we mixed hybrid sol to be dispersed and be stabilized by ball milling for 24hrs. By spin coating method, we makes thin film dielectric on the convectional green sheet for MLCC. After heat treatments, we analyzes the structure morphology, physical, electrical properties and X5R Temperature properties.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.4
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• pp.301-305
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• 2009

Pt nanoparticles with a narrow size distribution (dia. ~4 nm) were synthesized via an alcohol reduction method and used for the fabrication of hybrid Pt-$SiO_2$ nanoparticles. Also, the self-assembled monolayer of Pt nanoparticles (NPs) was studied as a charge trapping layer for non-volatile memory (NVM) applications. A metal-oxide-semiconductor (MOS) type memory device with Pt NPs exhibits a relatively large memory window. These results indicate that the self-assembled Pt NPs can be utilized for NVM devices. In addition, it was tried to show the control of thin-film thickness of hybrid Pt-$SiO_2$ nanoparticles indicating the possibility of much applications for the MOS type memory devices.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.236-245
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• 2017

Purpose: There is no established inspection system for composite wind blade during the fabrication stage even though the blades are one of the most important part at wind generation system, but phased array ultrasonic testing method has been continuously studied about wind turbine blade with composite. When wind turbine blade with complex shape by phased array probe is inspected, it is necessary to study for system keeping constant pressure using pressure device. Methods: In this paper, we propose constant pressure device for inspecting wind turbine blade by phased array ultrasonic test method. Design of the device controller is based on Hunt-Crossley model. We evaluate reliability of phased array ultrasonic inspection result that applicated constant pressure device. Result: Defect indication is precise and its error is small when constant pressure mechanism based on Hunt-Crossley model was used. Conclusion: When inspection is progressed using constant pressure mechanism, the reliability of composite wind blade inspection can be improved.