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웹기반 재료 데이터베이스 구축 및 자동차 엔진풀리용 재료선정 예
천두만(Doo-Man Chun),안성훈(Sung-Hoon Ahn),장재덕(Jae-Duk Jang) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.4
Material selection is one of the important activities in design and manufacturing. A selected material at the conceptual design stage affects functionality of the designed part as well as manufacturability and cost of the final product. Unfortunately there are not many accessible material databases that can be used for design. In this research, a web-based material database was constructed. In order to assist designers to compare different materials, two-dimensional and three-dimensional graphs were provided via the web browser. Using these graphical tools, multi-dimensional comparison was available in more intuitive manner. As a case study, this system was applied for material selection of an automotive engine pulley.
차량 경량화를 위한 사출성형 유리섬유강화플라스틱의 온도 및 수분 흡수에 따른 기계적 물성 변화
천두만(Doo-Man Chun),안성훈(Sung-Hoon Ahn) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.2
최근 차량 경량화를 통한 에너지 절감을 위해서 무거운 철강재료를 경금속이나 복합재료로 대체하는 연구가 많이 진행되고 있다. 이중, 폴리머 기반의 복합재료는 사출성형을 통해서 복잡한 형상의 제작이 가능하고, 유리섬유나 탄소섬유를 함께 사용하여 철강재료 수준으로 기계적 물성을 높일 수 있는 장점이 있다. 하지만 엔진의 고온과 우기에서의 높은 습도 환경은 폴리머의 기계적 물성을 낮추기 때문에 재료선택 과정에서 반드시 고려해야 한다. 본 연구에서는 사출성형을 통해 만들어진 유리섬유강화플라스틱을 엔진룸 내부 온도와 유사한 85℃ 환경과 우기시의 최대 수분흡수 환경하에서의 기계적 물성변화를 인장시험을 통해 알아보았다. 그 결과, 고온환경에서 최대인장강도가 약 23% 감소를 보였고, 수분에 의해서는 약 30% 감소하였으며, 고온과 수분 모두에 대해서는 약 70% 감소를 확인하였으며 이는 재료 선정시 반드시 고려해야 할 영향으로 판단되었다. Owing to the global energy crisis, studies have strongly focused on realizing energy savings through vehicle weight reduction using light metal alloys or polymer composites. Polymer composites afford many advantages including enabling the fabrication of complex shapes by injection molding, and glass and carbon fibers offer improved mechanical properties. However, the high temperature in an engine room and the high humidity during the rainy season can degrade the mechanical properties of the polymer. In this study, the mechanical properties of injection-molded glass-fiberreinforced polymer were assessed at a temperature of 85°C and the maximum moisture absorption conditions. The result showed a 23% reduction in the maximum tensile strength under high temperature, 30% reduction under maximum moisture absorption, and 70% reduction under both heat and moisture conditions. For material selection during the design process, the effects of high temperature and high humidity should be considered.
천두만(Doo-Man Chun),김민형(Min-Hyeng Kim),이재철(Jae-Chul Lee),안성훈(Sung-Hoon Ahn) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Nano particle deposition system (NPDS) is the newly developed ceramic and metal coating process. Nano and micro sized powders are sprayed through the supersonic nozzle at room temperature and low vacuum condition. Ceramic and metal powders can be deposited on metal and polymer substrates without thermal damages. In this research, ceramic titanium dioxide (TiO₂) thin films were deposited on metal (stainless steel, copper, aluminum) and polymer (polyethylene terephthalate and polymethyl methacrylate) substrates, and aluminum oxide (Al₂O₃) thin films were also deposited on metal (stainless steel and aluminum) substrates. In addition, metal tin (Sn) thin film was deposited on stainless steel substrate. Coatings were fabricated with rectangular and line shapes. Deposited surface morphology was investigated. The test results showed that the NPDS provides a feasible coating method of ceramic and metal materials.
천두만(Doo-Man Chun),윤해성(Hae-Sung Yoon),송성혁(Sung-Hyuk Song),김형중(Hyung-Jung Kim),안성훈(Sung-Hoon Ahn) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
The number of engineering materials is increasing, and the product development cycle becomes shorter. At the same time, the requirements for product design become wider because the consumers are interested in the environmental aspect and aesthetic aspect as well as functional aspect. Under this circumstance, engineering designers should consider the multi-dimensional aspects for product design at the same time. However, there are few tools for multi-dimensional design method. Most design methods can support optimization of one dimension or provide information of each dimension. In this research, multi-dimensional design method was studied for engineering material selection. Material information contains material property, environmental impact, and cost. All numerical values of multi-dimensional information were demonstrated with graphical approach and the order of preferable materials was suggested.
알루미늄 평판 및 50 ㎛ 간격 격자 표면에 대한 에탄올 액적 충돌 거동 가시화
강동국,권대희,천두만,염은섭,Kang, Dongkuk,Kwon, Daehee,Chun, Doo-Man,Yeom, Eunseop 한국가시화정보학회 2020 한국가시화정보학회지 Vol.18 No.1
The droplet impact behavior is dominated by some parameters such as surface temperature, We number, surface and fluid property. Especially, Leidenfrost effect which prevents the contact between surface and droplet is very powerful phenomenon for determining droplet impact behavior. Due to this effect, the impact regime is divided into contact boiling regime and film boiling regime whether the droplet contact with the surface. Many studies have found that surface micro-structures which processed by surface processing are effective to overcome the Leidenfrost effect. In this study, droplet impact behaviors were compared using ethanol both on flat and laser-ablated Al surface. On the flat surface, impact regime was mainly divided by surface temperature. And there is key dominant parameter for each regime. On the laser-ablated surface, we could see changed impact regime and different impact behavior such as jetting and ejection of tiny droplets despite of same impact conditions.
유동해석 결과를 구조해석에 적용하는 다물체 자료 변환 프로그램
이재철(Jae-Chul Lee),천두만(Doo-Man Chun),안성훈(Sung-Hoon Ahn,),장재덕(Jae-Duk Jang) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The finite element programs have been developed for structure, collision, flow, dynamics, heat transfer, acoustics, electromagnetism, MEMS (Micro Electro Mechanical Systems), and etc. These programs can be classified as “package” program and “single purpose” program. Single purpose programs usually have convenience and powerful functions, but these programs are difficult to expand into different fields of analysis. Therefore, the method to transfer the analysis results of single purpose program to other programs is needed. In the research, a multibody conversion method was created to input the flow analysis result of CFD-ACE+ to a package program, ANSYS. For example, the structure analysis of torque converter was conducted by the multibody conversion method.