• Composites Research
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• 제36권5호
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• pp.310-314
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• 2023

VaRTM(Vacuum assisted resin transfer molding)과 VAP(Vacuum assisted process) 공정은 RTM(Resin transfer modling) 공정의 한 종류로서, 대형구조물을 저가에 제작할 수 있는 대표적인 탈 오토클레이브(OOA, Out of Autoclave) 공정이다. 본 논문에서는 VaRTM과 VAP 공정을 상호 비교하기 위하여 수지 충진시험을 진행하였으며, 충진과정과 치수 안정성 등을 상호 비교하였다. 또한, 충진과정을 모사할 수 있는 해석기법을 개발하였으며, 유전센서를 사용하여 수지의 유동선단을 검출하여 이를 해석결과와 상호 비교하였다. 수지 충진시험 결과, 복합재 평판의 총 충진시간은 VAP공정은 48분, VaRTM 공정은 145분으로 측정되어, VAP 공정에 의한 충진시간이 VaRTM 대비 약 67% 단축되었으며, VAP공정이 VaRTM 공정에 비해 복합재 평판의 두께조절능력과 균일도가 우수함을 확인하였다.

• Composites Research
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• 제16권6호
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• pp.10-15
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• 2003

RTM 공정에 의하여 생성된 제품은 microvoids의 함유량에 의하여 기계적인 물성치에 큰 영향을 받는다. 본 연구에서는 이러한 microvoid의 형성과 이동을 실험적으로 관찰할 수 있는 방법을 제시하였다. Vacuum assisted RTM공정에서 유동선단에서의 microvoid의 형성과 이동을 DV camera로써 관찰을 한 후, 그것에서 void의 함유량을 구하고, 실험에서 얻어진 결과로 microvoid model에 필요만 factor들을 얻어낼 수 있었다. 이렇게 하여 얻어진 결과를 다시 실험적인 결과와 비교함으로써 서로 일치하는 결과를 얻어낼 수 있었다. 이번 연구에서 얻어진 결과를 수학적인 모델에 대입함으로써 VARTM 공정 중 microvoid의 함유량을 예측할 수 있다.

• Design & Manufacturing
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• 제12권2호
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• pp.5-10
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• 2018

Vacuum-assisted thermoforming is one of the critical steps for successful application of film insert molding(FIM) to parts of complex shape. In this study, the simulations and experiments of thermoforming processes were performed to investigate the effects of process conditions on thickness distribution and printed pattern deformation of films in vacuum-assisted thermoforming. The film thickness uniformity increased with decreasing film heating time, whereas it increased with increasing vacuum delay time. After thermoforming of films with uniform pattern space of 5mm, the maximum space was 9.432mm. Based on the simulation, a modified pattern was calculated to obtain uniform spaces after thermoforming. In the experiments for film with the modified pattern, the maximum space appeared 5.837mm. In, addition. the predicted patterns were in good agreement with the experimental results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.655-656
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• 2010

• 한국기계가공학회지
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• 제14권3호
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• pp.149-154
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• 2015

This study has focused on the deburring technology of a vacuum plate for MLCC lamination using electrolytic in-process dressing (ELID) grinding, and the magnetic-assisted polishing (MAP) process. The surface of the vacuum plate has many micro-holes for vacuum suction. They are easily blocked by the burrs created in the surface-flattening process, such as the conventional grinding process. In this study, the MAP process, the ELID grinding process, and an ultrasonic vibration table are examined to remove the micro-burrs that lead to the blockage of the holes. In the results of the experiments, the MAP process and ELID grinding technology showed significant improvements of surface roughness and deburring performance.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.465-465
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• 2012

In this study, we developed an Al2O3 nanolaminated single gas barrier layer using a Neutral Beam Assisted Sputtering (NBAS) process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nanocrystal phase with various grain sizes and lead to the formation of a nanolaminated structure in the single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the nanolaminated Al2O3 thin films by NBAS process have improved more than 40% compared with that of conventional Al2O3 layers by the RF magnetron sputtering process under the same sputtering conditions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.132-132
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• 2015

Virtual metrology (VM) model based on plasma information (PI) parameter for C4F8 plasma-assisted oxide etching processes is developed to predict and monitor the process results such as an etching rate with improved performance. To apply fault detection and classification (FDC) or advanced process control (APC) models on to the real mass production lines efficiently, high performance VM model is certainly required and principal component regression (PCR) is preferred technique for VM modeling despite this method requires many number of data set to obtain statistically guaranteed accuracy. In this study, as an effective method to include the 'good information' representing parameter into the VM model, PI parameters are introduced and applied for the etch rate prediction. By the adoption of PI parameters of b-, q-factors and surface passivation parameters as PCs into the PCR based VM model, information about the reactions in the plasma volume, surface, and sheath regions can be efficiently included into the VM model; thus, the performance of VM is secured even for insufficient data set provided cases. For mass production data of 350 wafers, developed PI based VM (PI-VM) model was satisfied required prediction accuracy of industry in C4F8 plasma-assisted oxide etching process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.171-171
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• 2012

Neutral beam assisted chemical vapor deposition (NBa-CVD) process has been developed as a nove,l room temperature deposition process for the light-soaking free nano-crystalline silicon (nc-Si) thin films including intrinsic and n-type doped thin film. During formation of nc-Si thin films by the NBa-CVD process with silicon reflector at room temperature, the energetic particles enhance doping efficiency and crystalline phase in nc-Si thin films without additional heating at substrate. The effects of incident NB energy controlled by the reflector bias have been confirmed by Raman spectra analysis. Additionally, TEM images show uniform nc-Si grains which imbedded amorphous phase without incubation layer. The nc-Si films by the NBa-CVD are hardly degenerated by light soaking; the degradations of photoconductivity were just a few percents before and after light irradiation.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.394-394
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• 2012

We fabricated organic-inorganic superlattice films using molecular layer deposition (MLD) and atomic layer deposition (ALD). The MLD is a gas phase process in the vacuum like to atomic layer deposition (ALD) and also relies on a self-terminating surface reaction of organic precursor which results in the formation of a monolayer in each sequence. In the MLD process, 'Alucone' is very famous organic thin film fabricated using MLD. Alucone layers were grown by repeated sequential surface reactions of trimethylaluminum and ethylene glycol at substrate temperature of $80^{\circ}C$. In addition, we developed UV-assisted $Al_2O_3$ with gas diffusion barrier property better than typical $Al_2O_3$. The UV light was very effective to obtain defect-free, high quality $Al_2O_3$ thin film which is determined by water vapor transmission rate (WVTR). Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of each organic, inorganic film. Composition of the organic films was confirmed by infrared (IR) spectroscopy. Ultra-violet (UV) spectroscopy was employed to measure transparency of the organic-inorganic superlattice films. WVTR is calculated by Ca test. Organic-inorganic superlattice films using UV-assisted $Al_2O_3$ and alucone have possible use in gas diffusion barrier for OLED.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.38-41
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• 2001

A new 2-D braided textile metal matrix composite was developed and characterized. The constituent materials consist of PAN type carbon fiber as reinforcements and pure aluminum as matrices. The braided preforms of different braider yarn angles were fabricated. For a fixed bundle size of 12K, three braider yarn angles was selected: $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$. The braided preforms were infiltrated with pure Al by vacuum assisted squeeze casting. Through the investigation of melt pressing methods and the effects of process parameters such as applied pressure, and pouring temperature, the optimal process conditions were identified as follows: applied pressure of 60MPa, pouring temperature of $800^{\circ}C$. Using the measured geometric parameters, 3-D engineering constants of metal matrix composites have been determined from the elastic model, which utilizes the coordinate transformation and the averaging of stiffened and compliance constants based upon the volume of each reinforcement and matrix material.