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355nm 펄스 레이저를 이용한 구리 표면의 소수성 개질에 관한 연구
윤단희,강보석,박준한,곽청렬,신보성,Yun, Dan Hee,Kang, Bo Seok,Park, Jun Han,Gwak, Cheng Yeol,Shin, Bo Sung 한국마이크로전자및패키징학회 2016 마이크로전자 및 패키징학회지 Vol.23 No.4
최근 자연모방을 이용한 소수성 표면 가공이 많은 관심을 끌고 있다. 대표적인 가공 방법으로 기계적 가공, 포토리소그래피 가공, 레이저를 이용한 공정이 있다. 본 논문에서는 구리필름에 UV 펄스 레이저를 직접 조사해 마이크로 그루브를 형성하고 상온에서의 산화를 통해 표면의 거칠기를 증가시켜 소수성 표면을 제작하였다. 패턴 생성 뒤 일정 시간 산화를 시킨 후에 측정된 접촉각은 산화를 시키기 전보다 약 $30{\sim}70^{\circ}$까지 증가함을 보인다. 본 연구 결과를 통해서 화학적인 처리과정 없이 보다 안정한 소수성 표면을 제조할 수 있음을 확인하였다. Recently, the hydrophobic surface has been attracted because of the excellent opto-physical properties. Various processing methods such as chemical, mechanical, photolithographic and laser processing are competitively introduced for fabrication of hydrophobic surface of polymer, metal and ceramics. In this paper, we fabricated the hydrophobic surface of copper metal by simple method which irradiated 355 nm UV-pulsed laser in order to shape microgrooves and increased surface roughness through oxidation process at room temperature. Finally the contact angle is dramatically increased by maximum $45^{\circ}$, as a result of oxidation which simply created nanostructures on the microstructures without expensive chemical process.
Study of Optimal Process Conditions of 3D Porous Polymer Printing for Personal Safety Products
유찬주(Chan-Ju Yoo),김혜수(Hyesu Kim),박준한(Jun-Han Park),윤단희(Dan-Hee Yun),신종국(Jong-Kuk Shin),신보성(Bo-Sung Shin) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.5
In this paper, a fundamental experiment regarding the formation of porous 3D structures for personal safety products using 3D PPP (Porous Polymer Printing) was introduced for the first time. The filament was manufactured by mixing PP (Polypropylene) and CBA (Chemical Blowing Agent) with polymer extruder, and the diameter of the filament was approximately 1.75mm. The proposed 3D PPP method, combined with the conventional FDM (Fused Deposition Modeling) procedure, was influenced by process parameters, such as the nozzle temperature, printing speed and CBA density. In order to verify the best processing conditions, the depositing parameters were experimentally investigated for the porous polymer structure. These results provide parameters under which to form a multiple of 3D porous polymer structures, as well as various other 3D structures, and help to improve the mechanical shock absorption for personal safety products.
워터젯 노즐의 길이와 내부 나선 구조 유무에 따른 유체거동에 관한 전산해석
곽청렬(Cheong-Yeol Gwak),신보성(Bo-Sung Shin),고정상(Jeung-Sang Go),김문정(Moon-Jeong Kim),유찬주(Chan-Ju Yoo),윤단희(Dan-Hee Yun) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.1
It is well known that water jetting is now widely used in the advanced cutting processes of polymers, metals, glass, ceramics, and composite materials because of some advantages, such as heatless and non-contacting cutting different from the laser beam machining. In this paper, we proposed the simulation model of waterjet by lengths and the inner spiral structure of the nozzle. The simulation results show that the outlet velocity of the nozzle is faster than the inlet. Furthermore, we found rapid velocity reduction after passing through the outlet. The nozzle of diameter ϕ500 and length 70mm, shows the optimal fluid width and velocity distribution. Also, the nozzle with inner spiral structure shows a Gaussian distribution of velocity and this model is almost twice as fast as the model without spiral structure, within the effective standoff distance (2.5 mm). In the future, when inserting abrasive material into the waterjet, we plan to analyze the fluid flow and the particle behavior through a simulation model.