• Composites Research
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• 제32권6호
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• pp.360-367
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• 2019

자전거 프레임 및 산업 부품과 같은 다양한 산업 분야에 PETG 열가소성 복합 재료를 적용하려면 제조 된 복합 재료의 내충격성, 내구성, 기계적 특성 및 3D 분석을 안정성 검증이 필수적이다. 본 연구에서는 비정질 수지인 PETG 수지의 기계적 특성, 내구성 및 내충격성을 향상시키기 위해 다양한 질량분율의 POE(폴리올레핀 엘라스토머)를 보강하여 화합물 및 사출 성형 공정을 수행 하였다. POE질량분율에 따른 PETG 열가소성 복합재의 열적 및 기계적 특성 및 샤르피 충격 강도 등에 대한 분석을 수행 하였다. 열적 및 기계적 특성 분석 결과, POE 소재가 첨가 된 PETG 열가소성 복합재의 경우 열적 및 기계적 특성이 감소하는 경향이 있지만 내충격성이 우수한 경향을 나타내었고, POE첨가에 따른 3D 전산해석 결과, 파손여부 없이 우수한 안정성을 나타내었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.315-324
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• 2001

Mechanochemical effects that occurred in the fine grinding process of quartz particles using planetary ball mill was investigated. Quartz particles have been frequently utilized for optical materials, semiconductor molding materials. We determined that grinding for a long time can be create amorphous structures from the crystalline quartz by Mechanochemical effects. But, to be produced nano-composite particles that the critical grinding time reached for composite materials in a short time. Henceforth, a qualitative estimation must be conducted on the filler for EMC(Epoxy molding compound) materials. It can be produced mechanochemically treated composite materials and also an integrated grinding efficiency considering of the nano-composite amorphous structured particles. The mechanochemical characteristics were evaluated based on particle morphology, size distribution, specific surface area, density and the amount of amorphous phase materials into the particle surface. The grinding operation in the planetary ball mill can be classified into three stages. During the first stage, initial particle size was reduced for the increase of specific surface area. In the second stage, the specific surface areas increased in spite of the increase in particle size. The final stage as a critical grinding stage, the ground quartz was considered mechanochemically treated particles as a nano- composite amorphous structured particles. The development of amorphous phase on the particle surface was evaluated by X-ray diffractometry, thermal gravity analysis and IR spectrometer. The amount of amorphous phase of particles ground for 2048 minutes was 85.3% and 88.2% by X-ray analysis and thermal gravity analysis, respectively.

• Design & Manufacturing
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• 제14권1호
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• pp.22-29
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• 2020

The analysis was carried out using the press molding analysis program by applying six parameters such as material type change, material thickness, friction coefficient, r_p, r_d and blank holder pressure. As a result of CAE analysis of the soft material DC04 and the relatively hard material HX300LAD, the thickness of the punch R part of the soft material was significantly reduced. The flange portion is greatly increased in thickness in the hard material by the compression action. As a result of considering the deformation amount of 0.6mm, 1.0mm, 1.5mm according to the material thickness, the influence of the thickness is considered to be very small. In case of the material thickness of 0.6mm, the rate of change increases due to the deep drawing depth relative to the material thickness. The sizes of the punches R and die R have the greatest influence on the change in thickness of the material in drawing molding, the smaller the punch R, the thinner the edges of the product, The larger the R of the die, the greater the material thickness of the flange portion. As the coefficient of friction and the blank holder pressure increase, the frictional force of the flange portion increases, which increases the radial force in the drawing process and increases the thickness change of the flange portion.

• 보존과학연구
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• 통권27호
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• pp.165-180
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• 2006

The research was conducted to understand type of iron used by those who lived at dwelling site of Yangsoo-ri in between the first century B.C. and the first century A.D. to make steel products and their technique such as steel making process and heat treatment, based on micro structure information obtained through microscopic metallographic structure analysis with SEM-EDS of six steel productsexhumed at the site. Key findings are summarized as below. In the sense that Si-Ca-Al style and less than 0.5% of Ti were found in the non-metallic inclusion, the material used for forged iron ware was magnetite resolved in that. It is, however, unclear whether magnetite was resolved at high temperature or at low temperature. Microscopic structure analysis revealed that forged steel products were made through repeated hot working, the technique of molding by hitting after heating in the process of resolving and molding iron. As a result, the iron used here for the products was not the iron ore which was produced through resolution from discarded cast iron axe, ingot iron. It is probable that to make those steel products, disposed-of cast iron was reused after being molded by decarburizing. Although a few of relics were analyzed for the research, they were of critical importance in defining the process of ironware production from the first century B.C. and the first century A.D. at the Yangsoo-ri region. Judging from the iron from A-19 dwellingsite, it is possible to conclude that the iron was manufactured from cast iron decarburized and yet more research has to be done into relics yetto be exhumed in order to ascertain the finding. All of these findings are believed to play a critical role in further studies to define the steel-manufacturing technique used on the central Korean peninsular in the ancient times.

• Composites Research
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• 제35권3호
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• pp.188-195
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• 2022

본 논문은 멀티스케일 공정-구조 해석의 방법론을 제안하고 단섬유층과 직물층으로 이루어진 배터리 하우징 파트에 적용한다. 특별히 마이크로스케일 대표체적요소(RVE: Representative Volume Element)안 기지의 불확정성을 고려하였다. 마이크로스케일의 RVE내 기지 물성의 랜덤한 공간내 분포는 KLE(Karhunen-Loeve Expansion)을 통해 구현하였다. 공간상 랜덤분포된 기지 물성을 갖는 RVE의 유효 물성을 전산균질화를 통해 얻어 매크로스케일 유한요소 모델에 매핑하였다. 또한 하이브리드 공정해석을 통해 압축 성형 해석으로부터 얻은 잔류응력과 섬유배향을 매핑한 유한요소 모델과 드레이핑 공정 해석결과로부터 얻어진 섬유배향을 매핑한 모델을 결합하였다. 본 연구에 제안된 방법은 배터리 하우징 뿐만 아니라 다양한 재료 구성을 갖는 복합재료의 공정-구조해석을 통해 설계요구도를 엄밀하게 평가할 수 있을 것이라 기대된다.

• Composites Research
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• 제32권5호
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• pp.249-257
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• 2019

In this paper, the buckling behavior of triaxially braided circular arch with monosymmetric open section subjected to three-point bending was studied experimentally and numerically. First, test specimens were manufactured using vacuum assisted resin transfer molding (VARTM). Then the specimen was tested under three-point bending to determine the ultimate buckling strength. Before performing the numerical analysis, effective material properties of the braided composite were obtained through micro-meso scale analysis virtual testing validated with available test results. Then linear buckling analysis and geometrically non-linear post buckling analysis, established to simulate the test setup, were performed to study the buckling behavior of the composite frame. Analysis results were compared with experimentally obtained ones for verification. The effect of manufacturing defects of tow misalignment, irregular surface and resin rich region, and uncertainties during test setup were studied using numerical models. From the numerical analyses performed it was observed that both manufacturing defect and uncertainties had effect on the buckling behavior and strength.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.525-526
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• 2008

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.43-44
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• 2012

본 논문에서는 도로조명용 LED 이차광학계의 제조공정에서 발행하는 형상오차를 설계에 반영하여 제작 후 형상 정밀도를 높여 궁극적으로 도로조명의 조명율을 향상시키는 방법을 제시하였다. 이를 통하여 동일한 에너지를 소모로도 더 높은 광밀도를 가질수 있는 LED2 차렌즈의 제조방법을 제시하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.443-444
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.439-440
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• 2012