• Journal of Welding and Joining
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• 제32권5호
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• pp.7-12
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• 2014

In this study, API-X100 steel pipes were welded with various kinds of welding wires in the laser-arc hybrid welding process. 10kW fiber laser source was combined to MIG arc welding process. API X-100 steel of base metal was of 16.9mm thickness, and butt welding applied. After welding, full penetration weld was acquired by 1-pass welding. A root porosity and the lack of fusion was observed in some welding conditions. By the mixing the melted wire, acicular ferrite, polygonal ferrite, pro-eutectoid, aligned side plate, and bainite structures were observed at the weld metal. From the observation of hybrid weld, unmixed zone had more Ni and Cr. The unmixed zone was a 1/3 area of the weld metal. As the mechanical test of the hybrid welding, tensile test and impact test applied. From the tensile test, all of the welding except SM70S was fractured at the base metal. The result of the impact test at -30 degree C led 60J~320J of the absorbed energy. The result of the low-absorbed energy might be from the coarse equiaxed structures of the weld metal.

• 한국생산제조학회지
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• 제24권1호
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• pp.94-97
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• 2015

In this study, we introduce a yellowing phenomenon in silver nanowire laser patterning and attempt to understand the cause of this phenomenon. Silver nanowire is a promising alternative to indium tin oxide as a transparent electrode owing to its flexibility. Additionally, silver nanowire can be easily patterned by laser ablation, which is free of dangerous chemicals. However, a yellowish color change reducing visibility is observed on the patterned area of the silver nanowires, and this yellowing phenomenon prevents the use of silver nanowire as a transparent electrode material. We concluded that resolidified debris of melted and evaporated silver nanowires after laser ablation causes the color change of the electrode. Further research is needed to determine a means of mitigating this yellowing phenomenon.

• 한국재료학회지
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• 제26권7호
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• pp.376-381
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• 2016

For the development of a low-melting point filler metal for brazing aluminum alloy, we analyzed change of melting point and wettability with addition of Sn into Al-20Cu-10Si filler metal. DSC results showed that the addition of 5 wt% Sn into the Al-20Cu-10Si filler metal caused its liquidus temperature to decrease by about 30 oC. In the wettability test, spread area of melted Al-Cu-Si-Sn alloy is increased through the addition of Sn from 1 to 5 wt%. For the measuring of the mechanical properties of the joint region, Al 3003 plate is brazed by Al-20Cu-10Si-5Sn filler metal and the mechanical property is measured by tensile test. The results showed that the tensile strength of the joint region is higher than the tensile strength of Al 3003. Thus, failure occurred in the Al 3003 plate.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.217-224
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• 2003

The frost and mist in the windshield disturb the sight of driver and passengers especially in winter. This possibly leads to safety problems. In order to export automobiles to the countries of North America, the safety regulation requires the frost of selected area should be completely melted in 30 minutes. The defrost pattern and time for melting of frost are fully dependent on the flow and temperature field near the windshield. Furthermore, the flow and temperature field near the windshield are dependent on the air discharged from defrost nozzle. The present work has been done for understanding the flow features of the discharged air and internal flow within the nozzle duct. The three dimensional Navier-Stokes code was used for performing the generic A/C duct flow analysis. The present results were nearly coincided with experimental data. To perform the parametric study of the effectiveness of the number of guide vanes, the discharge angle and the location of nozzle were changed. The ratio of volume flow rate through defrost nozzle and side exit were compared to investigate the influence of parameters on the effectiveness of defrost nozzle. The velocity profiles and flow patterns of the defrost nozzle duct were also analyzed.

• Journal of Welding and Joining
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• 제23권5호
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• pp.25-29
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• 2005

Steel has been mainly used in the automotive industry, because of good mechanical properties, weldability and so on. However, there has been increase in using aluminum to reduce the weight of vehicle. This leads to improve fuel efficiency and to reduce air pollution. A steel-aluminum hybrid body structure is recently used not only to reduce the weight of vehicle but also to increase safety. In this paper, the laser beam joining method is suggested to join steel and aluminum. To avoid making brittle intermetallic compounds(IMC) that reduce mechanical properties of the joint area, only aluminum is melted by laser irradiation and wetted on the steel surface. The brittle IMC layer is formed with small thickness at the interface between steel and aluminum. By controlling the process parameters, brittle IMC layer thickness is suppressed under 10 micrometers which is a criterion to maintain good mechanical properties.

• 한국정밀공학회지
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• 제22권6호
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• pp.55-60
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• 2005

This paper has been focused in developing of plastic lens with ultra-precision and low birefringence ability using by injection molding simulation tools. The simulation tools, $3D-Timon^{TM}\;and\;Asu-Mold^{TM}$ were applied to visualize indirectly the flow pattern of melted polymer enter the mould and the simulation results are verified as compared with the experimental results. Birefringence and polarized light generated in injection molding process was also calculated for each injection conditions and compared with .the pictures of experimented optical lens go through the polarized light plates device. A spherical radius of plastic optical lens transcribed from profile of mould core surface was measured to estimate the geometrical accuracy fer the each injection conditions. It is confirmed that the simulation results about flow pattern and polarized light area coincided in experimental results. It is known that increasing in thickness shrinkage at center of lens, the spherical radius is larger from comparing the graph measured spherical radius and the thickness shrinkage at center of lens

• Design & Manufacturing
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• 제12권3호
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• pp.19-24
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• 2018

Fused deposition Modeling (FDM) is one of the most widely used for the prototype of parts at ease. The FDM 3D printing method is a lamination manufacturing method that the resin is melted at a high temperature and piled up one by one. Another term is also referred to as FFF (Fused Filament Fabrication). 3D printing technology is mainly used only in the area of prototype production, not in production of commercial products. Therefore, if FDM 3D printer is applied to the product process of commercial products when considered, the strength and dimensional accuracy of the manufactured product is expected to be important. In this study, the mechanical properties of parts made by 3D printing with FDM method were investigated. The aim of this work is to examine how the mechanical properties of the FDM parts, by changing of processing FDM printing direction and the height of stacking layer is affected. The effect of the lamination direction and the height of the stacking layer, which are set as variables in the lamination process, by using the tensile specimen and impact specimen after the FDM manufacturing process were investigated and analyzed. The PLA (Poly Lactic Acid) was used as the filament materials for the 3D printing.

• 한국산학기술학회논문지
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• 제15권11호
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• pp.6472-6477
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• 2014

본 연구는 최근 영역을 넓히고 있는 일러스트 작가의 아트마케팅 트랜드를 살펴보고 색조화장품의 디자인 컨셉을 제안하고자 한다. 아트마케팅은 문화마케팅의 한 종류로 전시, 공연, 기타 예술 활동을 통한 마케팅을 의미한다. 아트와 생활의 경계가 모호해 지고 아트적인 모티브가 제품 속으로 녹아들고 아트적 속성이 다시 캔버스에 반영될 수 있는 자유로운 감성 표현이 주목받고 있다. 일러스트 작가의 작품들이 캔버스가 아닌 생활속의 아이템으로 영역을 넓히고 있는 것이다. 본 논문에서는 아트마케팅을 반영한 색조화장품 디자인을 제안하였다. 디자인 컨셉을 제안한 주요 타켓층은 20대 초중반의 젊은층으로 그들은 트랜드 지향적이며 개성이 강하고 스스로 인정받고 싶어하는 경향이 있다. 색조화장품 패키지 디자인에 디자인 컨셉을 강조하기 위하여 현란하고 강렬한 색상조합으로 타겟 계층의 진취적인 이미지를 반영하였다. 아트적인 무드가 생활속에 파고 들면서 우리 생활에 문화적 가치와 의미를 제공하고 있음을 알 수 있다.

• 한국광물학회지
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• 제27권4호
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• pp.197-205
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• 2014

하동군 북천면 직전리 지역은 하동 회장암체의 최남단부에 위치하고 있으며, 이 회장암체의 남서쪽에서 섬록암이 관입하여 나타난다. 이 지역의 회장암 및 섬록암 내에는 티탄철석 광체가 발달하고 있는데 이 중 섬록암 내의 산상은 기존의 연구에서 보고된 바 없다. 회장암 내 광체에서 산출되는 티탄철석은 단일광물로 산출되는 반면, 섬록암 내 광체에서 산출되는 티탄철석 내에는 티탄철석-산화철, 금홍석-산화철 간의 용리조직이 관찰된다. 티탄철석 내 MnO의 함량은 섬록암체 내 광체에서 2.14~3.74 wt%로 회장암 내 광체에서의 함량보다 높게 나타나며, 사장석은 섬록암체에서 안데신($An_{28.7-42.9}$)의 조성을 보여주고, 회장암에서 라브라도라이트($An_{57.1-72.8}$)의 조성을 보여준다. 섬록암 내 광체에서 산출되는 티탄철석에서 관찰되는 용리조직은 섬록암의 관입으로 공급된 열에 의해 부분 재용융이 일어나고 냉각과정에 티탄철석이 산화철과 금홍석으로 용리된 것으로 사료된다.

• Journal of the Korean Wood Science and Technology
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• 제23권1호
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• pp.54-60
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• 1995

This paper reports on the changes of equilibrium moisture contents and specific surface areas of Poplar wood(Populus euramericana) for various steam explosion treatments. Equilibrium moisture contents(EMC) and specific surfaces of steam exploded woods were measured under the moisture adsorption course at 25$^{\circ}C$, and compared with those of other materials and wood meals. The EMCs of steam exploded wood meal were 1~5% less in comparison with that of wood meal. In the case of delignified steam exploded wood meal and delignified wood meal, the same tendency was appeared too. But absolute values of EMCs for delignified wood meals were larger than those of the wood meal. For the changes of EMC by the steam exploded conditions, the EMC decreased with the increase of the steam explosion pressure. On the other hand, specific surface areas were calculated from BET plots based on amounts of monomolecular vapor adsorption of various wood meals. Specific surface areas of the wood meal and delignified wood meal were 90~145, 34~90($m^2/g$) respectively, and which were greater in comparison with those of steam exploded wood meals and delignified steam exploded wood meals. From these results, it is considered that the amount of water vapor adsorption was decreased by the increase of the crystallinity, effect of heat treatment, and coating by melted lignin in during the steam explosion.