• Transactions of Materials Processing
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• v.14 no.5 s.77
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• pp.477-481
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• 2005

Wafer scale micro mirror array with high surface quality for small form factor (SFF) optical pick-up was fabricated by micro UV-molding. To replicate micro mirror array for SFF optical pick-up, a high- precision mold was fabricated using micro-machining technology. Wafer scale micro mirror array was UV-molded using the mold and then the process was optimized experimentally. The surface flatness and roughness of UV-molded micro mirror array were measured by white light scanning interferomety system and analyzed the transcribing characteristics. Finally, the measured flatness of UV-molded micro mirror away for SFF optical pick-up, which was fabricated in the optimum processing condition, was less than 70nm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.12-18
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• 2009

In this paper, for reducing the assembly torque of subminiature plastic barrel and base which are the essential parts of mobile phone camera module, the high-precision system for inspecting the screw shape of core, electrode and injection molding products was developed. For realization of inspection process, the inspection parameters for evaluating the manufacturing quality were selected and the measurement methods of selected parameters were developed. Finally, the inspection system which is possible to be applied to the field were fabricated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.164-167
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• 2006

Micro lens especially for optical pick up(Blu-ray) lens module is one of the key products for IT technology. Specific attention has been given to manufacturing of large radius lens but little to small radius less than 2mm diameter with N.A>0.8. This paper deals with a high precision glass molding technology for mass production of Blu-ray pick up lens. Ultra precisely machined tungsten carbide core and glass molding equipments are utilized for forming process. Evaluation was performed in terms of profile accuracy, surface roughness and thickness of fabricated glass lens.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.47-50
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• 2005

In this study, micro mirror array for small form factor optical pick-up was replicated by micro UV-molding. First, mold for micro mirror array was fabricated using micromachining. Also, to analyze the characteristics of the surface quality, flatness of replicated mirror surface were measured by white light scanning inteferometry system. The results show that the micro mirror array with a sufficient surface quality can be obtained by polymer replication process.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.47-52
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• 2001

Micro-injection molding and microfluidic devices with the help of MEMS technologies including the LIGA process are expected to play important roles in. micro-system industries, in particular the bioapplication industry, in the near future. Understanding fluid flows in micro-channels is important since micro-channels are typical geometry in various microfluidic devices and mold inserts for micro-injection molding. In the present study, both experimental and numerical studies have been carried out to understand the detailed flow phenomena in micro-channel filling process. Three sets of micro-channels of different thickness were fabricated and a flow visualization system was also developed to observe the filling flow into the micro-channels. Experimental flow observations were extensively made to find the effects of channel width and thickness, and effects of surface tension and volume flow rate and so on. And a numerical analysis system has been developed to simulate the filling flow into micro-channels with the surface tension effect taken into account. Discussed are the flow visualization experimental observations along with the predictability of the numerical analysis system.

• Transactions of Materials Processing
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• v.19 no.6
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• pp.352-356
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• 2010

This paper was designed to fabricate the micro-spur gear by the LIGA and hybrid powder extrusion process. It is important to manufacture a micro-die with a high aspect ratio and determine appropriate extrusion conditions for a microforming. Ni has been used to fabricate micro-dies. LIGA process was capable to produce micro-extrusion dies with close tolerance, longer bearing length and adequate surface quality. Superplastic Al-78Zn powders have the great advantage in achieving deformation under low stresses and exhibiting good micro-formability with average strain rate raging from $10^{-3}$ to $10^{-2} s^{-1}$ and constant temperature ranging from 503 to 563K. Al-78Zn powders were compacted into a cylindrical shape ($\Phi3\times$h10mm) under compressive force of 10kN and, subsequently, the compacted powders were extruded by the hybrid powder extrusion process controlling of the temperature holing time for a improvement on formability of Al-22Zn powder. Micro-extrusion has succeeded in forming micro-gear shafts.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.1982-1988
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• 2002

Micro-injection molding and microfluidic devices with the help of MEMS technologies including the LIGA process are expected to play important roles in micro-system industries, in particular the bio-application industry, in the near future. Understanding fluid flows in micro-channels is important since micro-channels are typical geometry in various microfluidic devices and mold inserts for micro-injection molding. In the present study, Part 1, an experimental investigation has been carried out to understand the detailed flow phenomena in micro-channel filling process. Three sets of micro-channels of different thickness (40um,30um and 2011m) were fabricated using SU-8 on silicon wafer substrate. And a flow visualization system was developed to observe the filling flow into the micro-channels. Experimental flow observations are extensively made to find the effects of pressure, inertia force, viscous force and surface tension. A dimensional analysis for experimental results was carried out and several relationships A dimensionless parameters are obtained.

• Information and Communications Magazine
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• v.24 no.7
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• pp.26-35
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• 2007

최근 몇 년간 유비쿼터스 서비스를 구현하기 위한 핵심 기술 중 하나인 무선 센서 네트워크에 대한 관심이 높아지고 있다. 무선 센서 네트워크 기술은 물류, 유통, 환경 감시, 홈오토메이션, 군사 분야 등 다양한 분야에 적용 될 수 있기 때문에 앞으로 관련 분야의 시장 또한 커질 것으로 예상되고 있다 [1]. 무선 센서 네트워크는 기존 유선 센서 네트워크나 무선 네트워크 환경과는 많은 차이를 가진다. 우선 극도로 제한된 시스템 자원만을 가질 수 있으며, 열악한 환경 속에서 무선매체를 통해 유기적으로 동작하여야 하는 특징을 가지고 있다. 적게는 수십 개에서 많게는 수백, 수천 개의 자율적인 하드웨어 노드들로 구성되는 무선 센서 네트워크에서 제한된 자원을 효과적으로 활용하기 위해서는 센서 노드에 적합한 운영체제가 필수적으로 요구된다. 지난 몇 년간 센서 노드하드웨어의 발달과 더불어 많은 센서 네트워크용 초소형 운영체제가 개발되어왔다. 현재 많이 알려져 있는 센서 네트워크용 OS로는, 가장 활발한 참여를 보이고 있는 TinyOS[3]부터 SOS[4], MANTIS[5], Contiki[6], T-kernel[7] 등이 있으며, 국내 기술로 개발된 Nano-Qplus[8] 등이 존재한다. 본고에서는 우선 센서 네트워크에 대한 배경 지식과 플랫폼 등에 대한 내용을 간단히 다루고, 본론에서 센서 네트워크용 운영체제가 가져야 할 조건과 현재 개발되어 있는 센서 네트워크 OS들의 특징에 대해 간략히 살펴보도록 하겠다. 또한 센서 네트워크 OS와 밀접한 연관성을 가지는 분야에 대해 간단히 살펴보고, 마지막으로 앞으로의 방향에 대해 알아본다.고려해 볼 때 atlas의 장축의 시계방향 회전은 액티베이터의 사용 효과로 생각되며, 이는 차후 II급 부정교합자에서 액티베이터 치료 효과를 판단하는 또 하나의 지표가 될 수 있다고 생각한다.인해 한반도를 포함한 동아시아 대륙이 태평양판 쪽으로 밀려감으로써 섭입하던 태평양판의 각도가 급해져 동아시아 연변에 강력한 흡입력이 발생하였으며, 이 때문에 태평양판의 운동 방향이 북북서에서 서북서방향으로 회전되었을 가능성이 있다. 따라서 약 51 Ma부터 한반도 동남부에는 지판 경계의 강력한 흡입력으로 동서 내지 서북서-동남동의 인장력이 작동되어 B그룹 암맥군이 관입한 것으로 해석된다.Ledge는 세 군 모두에서 나타나지 않았다. 4. 파일 binding 횟수는 MC군이 가장 적고 PT군이 가장 많았다 (p < 0.05). 이상의 결과를 볼 때, Mtwo 전동 파일을 crown-down technique으로 사용하는 것이 single length technique과 유사한 성형 효율을 보이면서도 더 안전할 것으로 추정된다.고 1명(3%)에서 원격전이를 보였다. 치료 중 급성 합병증으로 11명(37%)에서 RTOG grade 1-2의 장염을 보였으며 1명은 대장의 천공이 발생하여 수술로 치유되었다. 12명(40%)에서 RTOG grade 1-2의 급성 방광염을 보였다. 3명(10%)에서 RTOG grade 1-2의 백혈구 감소증이 보였으며 1명에서 심한 백혈구 감소증(RTOG grade 4)이 나타났으나 회복되어 치료를 완료하였다. 만성 합병증으로 5명(15%)에서 RTOG grade 1-2의 만성 장염을 보였으며 별다른 치료 없이 지내고 있으며

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.3-8
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• 2006

The demand fer small and high-capacity optical data storage devices has rapidly increased. The areal density of optical disk is increased by using higher numerical aperture objective lens and shorter wavelength source. A wafer-scale stacked micro objective lens with a numerical aperture of 0.85 and a focal length of 0.467mm for the 405nm blue- violet laser was designed and fabricated. A diffractive optical element (DOE) was used to compensate the spherical aberration of the objective lens. Among the various fabrication methods for micro DOE, the UV-replication process is more suitable fur mass-production. In this study, an 8-stepped DOE pattern as a master was fabricated by photolithography and reactive ion etching process. A flexible mold was fabricated for improving the releasing properties and shape accuracy in UV-replication process. In the replication process, the effects of exposing time and applied pressure on the replication quality were analyzed. Finally, the surface profiles of master, mold and molded pattern were measured by optical scanning profiler. The geometrical deviation between the master and the molded DOE was less than $0.1{\mu}m$. The diffraction efficiency of the molded DOE was measured by DOE efficiency measurement system which consists of laser source, sample holder, aperture and optical power meter, and the measured value was $84.5\%$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.35-40
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• 2005

The demand for small and high-capacity optical data storage devices has rapidly increased. The areal density of optical disk is increased using higher numerical aperture objective lens and shorter wavelength source. A wafer-scale stacked micro objective lens with a numerical aperture of 0.85 and a focal length of 0.467mm for the 405nm blue- violet laser was designed and fabricated. A diffractive optical element (DOE) was used to compensate the spherical aberration of the objective lens. Among the various fabrication methods for micro DOE, the UV-replication process is more suitable for mass-production. In this study, an 8-stepped DOE pattern as a master was fabricated by photolithography and reactive ion etching process. A flexible mold was fabricated for improving the releasing properties and shape accuracy in UV-molding process. In the replication process, the effects of exposing time and applied pressure on the replication quality were analyzed. Finally, the shapes of master, mold and molded pattern were measured by optical scanning profiler. The deviation between the master and the molded DOE was less than 0.1um. The efficiency of the molded DOE was measured by DOE efficiency measurement system which consists of laser source, sample holder, aperture and optical power meter, and the measured value was $84.5\%$.