• 한국융합학회논문지
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• 제6권4호
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• pp.1-7
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• 2015

본 연구는 이과계통의 고교생들과 함께 연구한 연구(RESEARCH) 및 교육(EDUCATION)의 사례연구이다. 최근 발달한 사물인터넷(IoT)[9-15] 기반의 여러 가지 연구주제가 존재한다. 본 연구는 이들 중 이동형 통신기기중 가장 초보단계이면서도 학생들이 쉽게 접하고 제작방법을 따라 갈 수 있는 무선 호출기의 성형과정을 연구 주제로 정하였다. 우리는 이것을 페이저라고 한다. 오늘날 복잡하고 빅 데이터를 사용할 수 있는 대용량 스마트 이동형 통신기기[9-15]가 나와 있다. 그 이전 무선 호출기는 우리 삶에 이동 통신 수단의 첫 의미를 가르쳐 준 기기였다. 내부 구조도 비교적 간단하고 기능도 비교적 단순하여 이제 막 대학의 이공계에 관심을 가진 고교생들의 교육 사례로 적합하다고 생각된다. 본 연구는 사출성형 해석의 ONE CAVITY해석이라는 비교적 간단한 내용으로 무선호출기의 기구, 전자적인 내용을 모두 살펴볼 수 있다. 나아가 학생들에게 대량생산 및 공정자동화에 대한 융합교육의 의미도 일깨워 줄 수 있는 좋은 교육 사례로 평가된다.

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6047-6052
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• 2013

화장품제조업은 동일한 제품을 대량으로 생산하고 소비되는 구조로 금형을 통한 생산은 필연적이다. 화장품을 담는 용기는 소비자의 구매의사에도 영향을 주는 요소이며 완제품가격에서 차지하는 부분이 크기 때문에 경제성, 심미성과 기능성을 충족시키는 금형이 필요하다. 화장품 용기 중에 사각형태의 용기는 미성형 불량이 다른 형태의 제품보다 자주 발생하는 특징을 가진다. 기존에 사각형 형태의 화장품용기 제작공정은 2단 금형에 사이드게이트 구조로 금형을 제작하는데 이는 후가공과 게이트 흔적이 남는 단점이 있다. 본 연구에서 제안한 오버랩게이트는 후가공이 거의 없고 음각으로 게이트가 절단되는 특징이 있으며, 사이드게이트와 비교하여 Moldflow를 이용한 유동시스템을 시뮬레이션 하였다. 오버랩게이트가 유동성, 고화, 밀도, 에어트랩 등에서 유동성 향상과 불량률을 낮출 수 있는 결과를 확인하였으며, 해석결과를 기반으로 금형을 제작을 하고 사출성형 하였다. 본 연구를 통해 미성형 불량을 줄이고 심미성, 기능성 등의 특성을 가지는 화장품용기 제품의 대량생산 가능성을 검증하였다

• Design & Manufacturing
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• 제2권5호
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• pp.1-4
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• 2008

LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of kernel parts of LCD unit and it consists of several optical sheets(such as prism, diffuser and protector sheets), LCP (Light Guide Plate), light source (CCFL or LED) and mold frame. The LGP of LCD-BLU is usually manufactured by forming numerous dots with $50-200{\mu}m$ in diameter on it by erosion method. But the surface of the erosion dots of LGP is very rough due to the characteristics of the erosion process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. Especially, the negative and positive micro-lens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP.

• 소성∙가공
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• 제16권1호
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• pp.48-53
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• 2007

LCD-BLU(Liquid Crystal Display - Back Light Unit) consists of several optical sheets: LGP(Light Guiding Plate), light source and mold frame. The LGP of LCD-BLU is usually manufactured by etching process and forming numerous dots with $50{\mu}m$ in diameter on the surface. But the surface roughness of LGP with etched dots is very high, so there is much loss of light. In order to overcome the limit of current etched dot patterned LGP, optical pattern design with microlens of $50{\mu}m$ diameter was applied in the present study. The microlens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP and optical simulation was carried out to know tendency of microlens patterned LGP simultaneously. The attention was paid to the effects of different aspect ratio(i.e. $0.2\sim0.5$) of optical pattern conditions to the brightness distribution of BLU with microlens patterned LGP. Finally, high aspect ratio microlens patterned LGP showed superior results to the one made by low aspect ratio in average luminance.

• 한국분말재료학회지
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• 제8권1호
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• pp.49-54
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• 2001

The synthesis and characteristics of W-Ni-Fe nanocomposite powder by hydrogen reduction of ball milled W-Ni-Fe oxide mixture were investigated. The ball milled oxide mixture was prepared by high energy attrition milling of W blue powder, NiO and $Fe_2O_3$ for 1 h. The structure of the oxide mixture was characteristic of nano porous agglomerate composite powder consisting of nanoscale particles and pores which act as effective removal path of water vapor during hydrogen reduction process. The reduction experiment showed that the reduction reaction starts from NiO, followed by $Fe_2O_3$ and finally W oxide. It was also found that during the reduction process rapid alloying of Ni-Fe yielded the formation of $\gamma$-Ni-Fe. After reduction at 80$0^{\circ}C$ for 1 h, the nano-composite powder of W-4.57Ni-2.34Fe comprising W and $\gamma$-Ni-Fe phases was produced, of which grain size was35nm for W and 87 nm for $\gamma$-Ni-Fe, respectively. Sinterability of the W heavy alloy nanopowder showing full density and sound microstructure under the condition of 147$0^{\circ}C$/20 min is thought to be suitable for raw material for powder injection molding of tungsten heavy alloy.

• 한국정밀공학회지
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• 제29권8호
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• pp.896-905
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• 2012

Recently, the application of the plastic material to automotive components and structures has steadily increased to satisfy demands on the saving of overall weight and the improvement of energy efficiency. The objective of this paper is to investigate the development of a bumper back-beam using a thermoplastic olefin (TPO). The bumper back-beam was designed to be manufactured from the injection molding process. In order to obtain a proper design of the bumper back-beam, three-dimensional finite element analyses were performed for various design alternatives. Stress-strain curves for different strain rates were measured by high speed tensile tests of the TPO to consider strain rate effects in the FEA. The influence of the sectional shape and the rib formation on the contact force-intrusion curves, the deflection and the energy absorption rate of the bumper back-beam was examined. From the results of the examination, a proper design of the bumper back-beam was acquired. The bumper back-beam consisting of TPO was fabricated from the injection moulding process and the vibration welding. Pendulum crash tests were carried out using the fabricated bumper back-beam. The results of the tests showed that the designed bumper back-beam can satisfy requirements of the federal motor vehicle safety standard (FMVSS). Through the comparison of the previously designed bumper back-beam with the newly designed bumper back beam, it was noted that the weight of the designed bumper back-beam is lighter than that of the previously designed bumper back beam by nearly 16 %. In addition, it was considered that the newly designed bumper back beam can improve recycling of the bumper back-beam.

• Composites Research
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• 제33권6호
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• pp.383-389
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• 2020

열가소성 복합재료를 적용하여 자동차 도어 임팩트 빔을 설계하고 시생산을 통해 생산성 및 성능을 검증하였다. 자동차 안전법규는 지속적으로 강화되어 왔으며 최근 자동차 산업에서 경량화가 필수 요건이 되면서 고성능 경량 부품에 대한 요구가 크게 증대되고 있다. 본 연구는 섬유강화 열가소성 복합소재를 도입하여 기존 탄소강 제품 대비 경량화 되면서 성능은 향상된 도어 임팩트 빔 개발을 목표로 하였다. 연속섬유 복합재료와 장섬유 복합재료(LFT)를 혼합 적용한 도어 임팩트 빔 제작 공정을 제시하며, 생산성이 우수한 인서트 사출 공정을 활용하여 구현하였다. 시생산된 도어 임팩트 빔은 3점 굽힘 시험을 통하여 성능을 평가하였다. 열가소성 복합재료는 경량화 설계와 함께 높은 생산성 구현이 가능하여 다양한 자동차 부품으로 복합소재의 적용을 확대시킬 것이다.

• 한국정밀공학회지
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• 제17권4호
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• pp.7-21
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• 2000

This paper describes an overview of the thixoforming and thixomolding processes. Semi-solid metalworking (SSM), which is called the thixoforming process of aluminium materials, incorporates the elements of both casting and for the manufacture of near net shape parts. The SSM has some advantages such as net shape or near net shape manufacturing, the ability to form thin walls, excellent surface finish, tight tolerance, and excellent dimensional precision. The thixomolding process of Mg alloy (AZ9l) is a combination of two technologies both conventional die casting and plastic injection molding. The feed material used is a machined chip with a geometry of approximately 1 mm square and a length of 2~3 mm. The semi-solid forming (SSF) of high quality aluminium and magnesium parts will be established in the automotive and electronic industry, in the future. The hybrid method of casting/forging has been caused attention. This process uses a preformed material made by casting instead of the wrought material and finishes it by a single forging process. This process is expected to lower costs without sacrificing the mechanical and finishes it by a single forging process. The process is expected to lower costs without sacrificing the mechanical properties. The authors, intending that the casting/forging process contributes to a reduction in production cost of aluminum automotive parts in Korea, describes the feature of the casting/forging process, aluminum alloys suitable for the cast preform, microstructure and mechanical properties of the cast preform, application examples of cast/forging, and further study.

• Design & Manufacturing
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• 제7권1호
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• pp.55-59
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• 2013

A Light Emitting Diode(LED) is a semiconductor device which converts electricity into light. LEDs are widely used in a field of illumination, LCD(Liquid Crystal Display) backlight, mobile signals because they have several merits, such as low power consumption, long lifetime, high brightness, fast response, environment friendly. In general, LEDs production does die bonding and wire bonding on board, and do silicon and phosphor dispensing to protect LED chip and improve brightness. Then lens molding process is performed using mixed liquid silicon rubber(LSR) by resin and hardener. A mixture of resin and hardener affect the optical characteristics of the LED lens. In this paper, computational design of static mixer was performed for mixing of liquid silicon. To evaluate characteristic of mixing efficiency, finite element model of static mixer was generated, and fluidic analysis was performed according to length of mixing element. Finally, optimal condition of length of mixing element was applied to static mixer from result of fluidic analysis.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.25-29
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• 2019

Various process technologies for manufacturing power inductors are under development. The core goal is to increase the mixing ratio of the soft magnetic powder in the epoxy, and to uniformly disperse it in a molding-type power inductor, manufactured by the injection molding method. In this study, we investigated the effect of dispersant and silane on the dispersion of soft magnetic metal powders in epoxy. We added 0.6 wt% of dispersant and 2.0 wt% of silane, and an excellent dispersibility resulted. Under the conditions of 0.3 wt% of dispersant and 0.5 wt% of silane, we added both dispersant and silane together to observe the effect of their interaction on dispersibility. Similarly, the addition of 0.3 wt% of dispersant and 0.1 wt% of silane resulted in a sharp increase in viscosity, considered to be due to the interaction of the dispersant and silane. The addition of 0.1 wt% of dispersant with 0.5 wt% of silane resulted in a sharp rise in viscosity, and sedimentation-height decreased sharply due to the dispersion optimization.