• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.229-232
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• 2005

This paper presents the design and fabrication of backflow prevented Micropump using the metal membrane. The Micropump is consisted of the lower plate, metal membrane, upper plate and the piezoelectric-element. The lower plate includes the micro channel and the inlet, outlet of the Micropump. The upper plate includes the micro channel and connects the piezoelectric-element. These plate are fabricated on the Pyrex glass wafer by sandblasting process. The metal membrane does roll of check valve that is prevented backflow of the Micropump. The metal membrane is fabricated on the stainless steel by laser machining. Piezoelectric-element is actuated the Micropump and controlled flowing of fluid. The Micropump is fabricated by bonding process of these multi-layer.

• 대한심미치과학회지
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• 제25권2호
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• pp.98-108
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• 2016

전통적인 Metal-ceramic 보철 제작 방식으로부터 All-ceramic 보철에 이르기까지 최근 신소재 개발에 영향을 주는 가장 큰 요인은 심미적인 욕구일 것이다. 우리가 사용하는 각각의 치과용 수복 재료는 재료 별로 강도, 인성, 기계 가공의 효율성 및 사용에 필요한 다양한 과정을 기반으로 임상에서 다양하게 사용되고 있다. 예를 들어 Glass ceramic과 같은 단일 소재의 경우 약한 물성을 고려하여 주로 싱글 크라운과 같은 간단한 보철에 사용하고 있으며 상대적으로 높은 파괴 인성을 가진 지르코니아 재료의 경우 싱글 크라운은 물론 브릿지의 제작에도 널리 사용하고 있다. 하지만 지르코니아 재료는 제작 과정에서 긴 Sintering 시간을 필요로 하므로 Chair side에서 빠른 보철물 제작에 쉽지 않은 부분이 있으며 주로 Lab. side에서 사용하고 있다. CAD / CAM 시스템을 이용하여 보철물을 제작하는 용도로 개발 된 Hybrid ceramic 소재는 Resin Nano Hybrid Ceramic이라고도 하며, 개선 된 물성을 포함한 나노 세라믹 요소를 기반으로 하고 있다. 이러한 특징들은 심미적이며 기능적인 보철물의 제작이 용이한 과정과 결과를 보이고 있으며 동시에 향상된 내구성을 바탕으로 보철물의 제작 과정에 유리한 조건들을 가지고 있다. 새로운 Nano Hybrid Ceramic 재료는 Composite Resin과 Glass ceramic과 같은 단일 소재들이 가진 장점들을 이용하여 술자들의 요구사항을 바탕으로 오랜 연구를 통해 개발된 치과 수복 아이템이며 Nano ceramic filler가 혼합된 구조로 되어있어 치과 수복용 복합소재로서 널리 사용하고 있다. 또한 Nano Hybrid Ceramic소재는 Composite resin의 가공 과정에서 쉽게 파절되지 않는 개선된 물성과 Glass ceramic이 가진 심미성 동시에 포함하고 있는 것이 특징이다. 따라서 Chair side와 Lab. side에서 CAD/CAM 시스템을 이용하여 보철물을 제작할 때 임상적용이 쉽고 유용한 장점을 가지고 있어 추가적인 연구가 필요하다.

• 대한기계학회논문집A
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• 제36권6호
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• pp.591-598
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• 2012

본 연구에서는 CNC선반을 사용하여 다양한 공구재질과 절삭속도에서 벌크금속유리(BMG)의 절삭 특성을 평가하였다. 선반가공시 Zr-기 BMG의 표면거칠기와 칩 형상을 관찰하여 가공조건에 따른 절삭력과 공구툴 마모 등 절삭 특성을 비교 검토하였다. 직경 8 mm $Zr_{50}Cu_{40}Al_{10}$ BMG시험편의 절삭에는 네 종류의 절삭공구를 사용하였다. 가공후 BMG 시험편의 표면거칠기를 측정하였고, 표면거칠기에 미치는 공구 회전속도의 영향을 조사하였다. 회전속도가 빠를수록 낮은 표면거칠기를 나타내었고, 공구 재질의 영향도 크게 나타났다. 칩 형상의 관찰 결과, 산화를 일으키지 않은 BMG 칩은 단열 전단띠 발생과 함께 나선형상의 형태를 나타내지만, 산화를 일으킨 칩은 국부적으로 용융과 함께 칩들이 뭉치는 현상을 나타내었다. BMG시험편을 가공하는 동안 발생한 절삭력은 TiN-WC에서 가장 큰 값을 나타내고, PCD가 그 다음, Cermet툴에서 가장 작은 값을 나타내었다.

• 한국정밀공학회지
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• 제26권7호
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• pp.44-50
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• 2009

High-pressured 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. Similarly to the focused laser beam machining, it is well known as a type of high-density energy processes. High-pressured jetting is going to be developed not only to minimize the cutting line width but also to achieve the short cutting time as soon as possible. However, the interaction behavior between a work piece and high-velocity abrasive particles during the high-pressured jet cutting makes the impact mechanism even more complicated. Conventional high-pressured jetting is still difficult to apply to precision cutting of micro-scaled thin work piece such as thin metal sheets, thin ceramic substrates, thin glass plates and TMM (Thin multi-layered materials). In this paper, we proposed the advanced high-pressured jetting technology by introducing a new abrasives supplying method and investigated the optimal process conditions of the cutting pressure, the cutting velocity and SOD (Standoff distance).

• 소성∙가공
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• 제18권4호
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• pp.310-316
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• 2009

Micro lens array(MLA) is widely used in information technology(IT) industry fields for various applications such as a projection display, an optical power regulator, a micro mass spectrometer and for medical appliances. Recently, MLA have been fabricated and developed by using a reflow method having the processes of micro etching, electroplating, micro machining and laser local heating. Laser thermal relaxation method is introduced in marking of microdots on the surface of densified glass. In this paper, we have proposed a new direct fabrication process using UV laser local thermal-expansion(UV-LLTE) and investigated the optimal processing conditions of MLA on the surface of negative photo-resist material. We have also studied the 3D shape of the micro lens obtained by UV laser irradiation and the optimal process conditions. And then, we made chrome mold by electroplating. After that, we made MLA using chrome mold by hot embossing processing. Finally, we have measured the opto-physical properties of micro lens and then have also tested the possibility of MLA applications.

• 한국정밀공학회지
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• 제22권3호
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• pp.115-122
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• 2005

As the digital TV markets rapidly growing, many manufacturers introduce large size flat screen TV units. There are two different display types available to large size models which are plasma and TFT-LCD. Since both are constructed with thin large panels that are mostly fragile to even moderate mechanical shock inputs. Some large size panels are severely resonated by the acoustic sound generated TV which deteriorates video quality. Recognizing the potential problems of large displays, accurate measurement of the panels is to be an essential task for the reliable design. Measurement of mechanical properties of a thin large crystallized panel such as TFT-LCD display with traditional material testing equipments is challenging. Since TFT-LCDs are constructed with combination of brittle glass panels, polymer sheets, and liquid crystal, their properties are not only anisotropic but also usually non-linear. Accurate measurement of the properties often requires very expensive facilities. Especially when the size of the test sample is as large as 40-inch or wider, direct measurement cost is prohibitive. Even worse, machining of the large TFT-LCD to make a smaller size specimen that could be fit into a material tester is not possible because of liquid crystal leakage. A new method fer the measurement of elastic modulus of large TFT-LCD panel is presented in this article. The suggested method provides a simple, economic, and user-friendly way fer measuring the elastic modulus of large panels with considerable level of accuracy.

• Design & Manufacturing
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• 제14권2호
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• pp.14-20
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• 2020

In OLED panel production process, it is necessary to cut a part of protective film as a preprocess for lighting inspection. The current method is to recognize only the fiducial mark of the cut-out panel. Bare Glass Cutting does not compensate for machining cumulative tolerances. Even though process defects still occur, it is necessary to develop technology to solve this problem because only the Align Mark of the panel that has already been cut is used as the reference point for alignment. There is a lot of defective lighting during panel lighting test because the correct protective film is not cut on the panel power and signal application pad position. In laser cutting process to remove the polarizing film / protective film / TSP film of OLED panel, laser processing is not performed immediately after the panel alignment based on the alignment mark only. Therefore, in this paper, we performed real time inspection which minimizes the mechanism tolerance by correcting the laser cutting path of the protective film in real time using Machine Vision. We have studied calibration algorithm of Vision Software coordinate system and real image coordinate system to minimize inspection resolution and position detection error and edge detection algorithm to accurately measure edge of panel.

• 한국기계가공학회지
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• 제16권1호
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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.

• Current Optics and Photonics
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• 제1권4호
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• pp.364-371
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• 2017

Compared to one made of glass, an aluminum mirror features light weight, compact design, low cost, and quick manufacturing. Reflective mirrors and supporting structures can be made from the same material, to improve the athermal performance of the system. With the rapid development of ultraprecise machining technologies, the field of applications for aluminum mirrors has been developed rapidly. However, most of them are rotationally symmetric in shape, and are used for infrared applications. In this paper, the design and manufacture of an off-axis aluminum mirror used for a three-mirror-anastigmat (TMA) optical system at visible wavelengths is presented. An optimized, lightweight design provides a weight reduction of more than 40%, while the surface deformation caused by earth's gravity can meet the required tolerance. The two pieces of an off-axis mirror can be diamond-turned simultaneously in one setup. The centrifugal deformation of the off-axis mirror during single-point diamond turning (SPDT) is simulated through the finite-element method (FEM). The techniques used to overcome centrifugal deformation are thoroughly described in this paper, and the surface error is reduced to about 1% of the original value. After post-polishing, the form error is $1/30{\lambda}$ RMS and the surface roughness is better than 5 nm Ra, which can meet the requirements for visible-light imaging.