• 한국주조공학회지
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• 제41권6호
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• pp.521-527
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• 2021

본 연구는 고압 다이캐스팅 공정에서 제품 결함을 사전에 예측하기 위한 기계 학습 기반의 공정 관리 모델 개발에 관한 연구이다. 모델은 이전 사이클에서의 온도를 입력받고, 사이클에 걸쳐서 나타나는 특징을 인식하여 다음 사이클의 결함 발생 여부를 예측한다. 기어 박스 형상에 대하여 제안된 알고리즘을 적용하여, 3 사이클의 정보를 통해서 98 .9%의 정확도와 96.8 %의 재현율로 제품 수축 결함을 사전에 예측하였다.

• 한국수소및신에너지학회논문집
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• 제32권3호
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• pp.189-195
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• 2021

A compressed hydrogen tank is to be repressurized to 40 bar by being connected to a high-pressure line containing hydrogen at 50 bar and 25℃. Hydrogen filling time and the corresponding hydrogen temperature has been estimated when the filling process stopped according to several thermodynamic models. During the process of cooling the hydrogen tank, hydrogen temperature and pressure vs. time estimation was performed using Aspen Dynamics. Filling time, hydrogen temperature after filling hydrogen gas, cooling time and the final tank pressure after tank filling process have been completed according to the thermodynamic models are almost same.

• 대한전자공학회논문지
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• 제22권1호
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• pp.34-40
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• 1985

시스뎀 압력이 1.0 기압[대기압 공정]일 경우와 0.1 기압(감압 공정)일 경우에 대해, SiH2Cl2를 사용했을 때의 에퍼택셜층 및 폴리실리콘의 성장 현상과 HCI을 사용했을 때의 이것들의 에칭 현상을 조사하였다. 실험적으로 구한 성장 속도 및 에칭 속도에 대한 식들로부터 Sih2Cl2와 HCI을 혼합하여 사용할 경우에 대한 선화적 에퍼택시가 가능한 공정 조건이 예측되었다. 그 결과, 선택적 에퍼택셜 성장 영역이 감압 공정에서는 실험 범위내에서 존재하였지만 대기압 공정에서는 존재하지 않는 것으로 나타났다. 이 것은 대기압과 감압에서의 성장 속도 및 에칭 속도가 차이가 나기 때문에 기인하는 것이다.

• 소성∙가공
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• 제18권8호
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• pp.633-639
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• 2009

Remarkable progress had been made in both technology and production of optical elements including aspheric lens. In the past, precision optical glass lenses were produced through multiple processes such as grinding and polishing, but mass production of aspheric lenses requiring high accuracy and having complex profile was rather difficult. Against such a background, the high-precision optical GMP process was developed with an eye on mass production of precision optical glass pasts by molding press. This GMP process can produce with precision and good repeatability special form lenses such as for cameras, video cameras, aspheric lenses for optical items. In this study, Design Of Experiment(Taguchi method) was adopted to find a tendency of molding conditions that influence formability. Three main factors for molding conditions were selected based on pressure at pressing stage and temperature, pressure at cooling stage. Also, the DOE was carried out and the interference patterns were measured to evaluate the formability of GMP process. From the results, it was found that the cooling pressure is the most sensitive parameter for progressive GMP process.

• 소성∙가공
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• 제15권3호
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• pp.220-225
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• 2006

This paper investigates the characteristics of a hydro-mechanical punching process. The hydro-mechanical punching process is divided into two stages: the first stage is the mechanical half piercing in which an upper punch goes down before the initial crack is occurred; the second stage is the hydro punching in which a lower punch goes up until the final fracture is occurred. Ductile fracture criteria such as the Cockcroft, Brozzo and Oyane are adopted to predict the fracture of sheet material. The index values of ductile fracture criteria are calculated with a user material subroutine, VUMAT in the ABAQUS Explicit. The hydrostatic pressure retards the initiation of a crack in the upper region of the blank and induces another crack in the lower region of the blank during the punching process. The final fracture zone is placed at the middle surface of the blank to the thickness direction. The result demonstrates that the hydro-mechanical punching process makes a finer shearing surface than the conventional one as hydrostatic pressure increases.

• 폴리머
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• 제24권5호
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• pp.690-700
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• 2000

본 연구에서는 온도의 상승에 의하여 부피가 팽창하는 열팽창 고무 치공구의 팽창 특성을 이용하여 열경화성 복합재료를 경화하고 압축하는 과정을 실험과 모델링을 통하여 해석하였다. 열팽창 고무치공구가 사용되는 닫힌계 (fixed-volume process)와 열린계 (variable-volume process)에서 예상되는 압력을 이론적으로 유도하였고, 경화가 수반되는 과정에 있어서는 실험을 통하여 열팽창 치공구와 프리프레그가 나타내는 압력을 측정하였다. 온도가 상승하고 경화가 수반되는 경우에 등속도 압축실험에 의하여 얻어진 응력-변형율 곡선은 비선형 점탄성 특성을 보여주었는데, 본 연구에서는 Maxwell모델을 KWW (Kohlrausch-Williame-Watts)식으로 변형시킨 모델식을 이용하여 이를 매우 정확하게 표현할 수 있었다. 이 모델을 이용하여 몰드의 부피를 고정시킨 상태에서 경화시키는 닫힌계 공정에서 예상되는 압력을 예측하였으며 따라서 열팽창 치공구를 열경화성 복합재료의 경화압축 공정에 성공적으로 적용하였고 이를 해석하였다.

• 대한조선학회논문집
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• 제55권5호
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• pp.415-420
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• 2018

The development of sail gas has increased the production of ethane as well as natural gas. The decline in the market price for ethane has led to a change in the petroleum-based ethylene production process into an ethane-based ethylene production process and an increase in the ethane/ethylene trade volume. Large-scale ethane/ethylene carrier have been needed due to an increase in long-distance trade from the US, and cargo type change have leaded to consider a liquefaction process to re-liquefy Boil-Off gas generated during the voyage. In this paper, the liquefaction system of Liquefied Ethane Gas carrier was evaluated with Low-GWP (Low-Global Warming Potential) refrigerant and process parameters, Boil-Off Gas pressure and expansion valve outlet pressure, were optimized. Low-GWP refrigerants were propane (R290), propylene(R1270), carbon dioxide(R744) was considered at two type of liquefaction process such as Linde and cascade cycle. The results show that the optimal pressure point depends on the individual refrigerant and the highest liquefaction efficiency of carbon dioxide (R744) - propane (R290) refrigerant.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.185-188
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• 2001

Chemical mechanical polishing(CMP) process is widely used for global planarization of inter-metal dielectric (IMD) layer and inter-layer dielectric (ILD) for deep sub-micron technology. However, as the IMD and ILD layer gets thinner, defects such as micro-scratch lead to severe circuit failure, which affect yield. In this paper, for the improvement of CMP Process, deionized water (DIW) pressure, purified $N_2$ (P$N_2$) gas, slurry filter and high spray bar were installed. Our experimental results show that DIW pressure and P$N_2$ gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. Also, the filter installation in CMP polisher could reduce defects after CMP process, it is shown that slurry filter plays an important role in determining consumable pad lifetime. The filter lifetime is dominated by the defects. However, the slurry filter is impossible to prevent defect-causing particles perfectly. Thus, we suggest that it is necessary to install the high spray bar of de-ionized water (DIW) with high pressure, to overcome the weak-point of slurry filter. Finally, we could expect the improvements of throughput, yield and stability in the ULSI fabrication process.

• 센서학회지
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• 제26권1호
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• pp.24-27
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• 2017

In this study, I developed a simple and low cost process-printing a silver, carbon, dielectric, adhesive layer on PET films using screen printing technology and bonding the two films face-to-face-to fabricate a low price capacitive pressure-mapping sensor. Both electrodes forming the pressure measuring capacitor are arranged between the two PET films similar to a sandwich. Therefore, the sensor has the advantage of minimizing the influence of external noise. In this study, a $10{\times}10$ capacitance-type pressure-mapping sensor was fabricated and its characteristics were analyzed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.264-270
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• 2002

The frost heaving pressure can be a problem for weakening of the railroadbed material. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. This pressure is induced as a result of a curved ice-water interface. This study was initiated to investigate the soils frost heaving expansion pressure and physical characteristics resulting from freezing and freezing-thawing cycle process. Weathered granite soils, sandy soil were used in the laboratory freezing test subjected to thermal gradients under closed-systems.