• 대한수학회지
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• 제45권4호
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• pp.965-976
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• 2008

In this article, we constructively prove that on a surface S with genus g$\geq$2, there exit maximal geodesic laminations with 7g-7,...,9g-9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g-7,...,9g-9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F-E+V, where F, E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal cell decompositions.

• 반도체디스플레이기술학회지
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• 제16권3호
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• pp.116-120
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• 2017

Temperature uniformity of a wafer in a semiconductor process is a very important factor that determines the overall yield. Therefore, it is very important to confirm the temperature characteristics of the chuck surface on which the wafer is lifted. The temperature characteristics of the chuck depend on the external heat source, the shape of the cooling channel inside the chuck, the material on the chuck surface, and so on. In this study, CFD confirms the change of temperature characteristics according to the stacking order of ceramic materials on the chuck surface, and suggests the best lamination method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.716-721
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• 2004

Several Solid Freeform Fabrication Systems(SFFS) are commercialized in a few companies for rapid prototyping. However, they have many technical problems including the limitation of applicable materials. A new method of speedy prototyping is required for the recent manufacturing environments of multi-item and small quantity production. The objectives of this paper include the development of a novel method of SFFS, the ${CAFL}^{VM}$(Computer Aided Fabrication of Lamination for Various Material), and the manufacture of the various material samples for the certification of the proposed system and the creation of new application areas. For these objectives, the technologies for a highly accurate robot path control, the optimization of support structure, CAD modeling, adaptive slicing was implemented. In this paper, we design an algorithm that the cutting path of a laser beam which is controlled with constant speed. The laser beam is tangentially controlled in order to solve the inaccuracy of a 3D model surface. The designed algorithm for constant-speed path control and tangent-cutting control is implemented and experimented in the ${CAFL}^{VM}$ system.

• Advances in concrete construction
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• 제9권1호
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• pp.43-54
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• 2020

This paper presents an innovative stress-function variational approach in formulating the interfacial shear and normal stresses in an externally bonded concrete joint using carbon fiber-reinforced plastic (CFRP) plies. The joint is subjected to surface traction loadings applied at both ends of the concrete substrate layer. By introducing two interfacial shear and normal stress functions on the CFRP-concrete interface, based on Euler-Bernoulli beam idea and static stress equations of equilibrium, the entire stress fields of the joint were determined. The complementary strain energy was minimized in order to solve the governing equation of the joint. This yields an ordinary differential equation from which the interfacial normal and shear stresses were proposed explicitly, satisfying all the multiple traction boundary conditions. Lamination theory for composite materials was also employed to obtain the interfacial stresses. The proposed approach was validated by the analytic models in the literature as well as through a comprehensive computational code generated by the authors. Furthermore, a numerical verification was carried out via the finite element software ABAQUS. In the end, a scaling analysis was conducted to analyze the interfacial stress field dependence of the joint upon effective issues using the devised code.

• 한국정밀공학회지
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• 제19권2호
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• pp.87-94
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• 2002

Most of Rapid Prototyping (RP) process adopt a solid Computer Aided Design (CAD) model, slicing into thin layers of uniform, but not necessarily constant, thickness in the building direction. Each cross-sectional layer is successive1y deposited and at the same time, bonded onto the previous layers; the stacked layers form a physical part of the model. The objective of this study is to develop a method for calculating the rotation angle ($$\theta$_x, $\theta$_y$) of hotwire of the cutting system in the three-dimensional space for the Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-S). In order to examine the applicability of the developed method to VLM-S, various three-dimensional shapes. such as a screw, an extruded cross, and free surface bodies such as miniatures of the monkey(a figure of Sonokong), were made using the data obtained form the method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.13-14
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• 2008

In this paper, we analyze the electrical characteristics of PV depending on distance among solar cells before and after lamination process. From the result, the PV module's maximum power increases about 3.37% when solar cells's distance is 10mm. And the maximum power increases up to 8.42% when solar cells's maximum distance is 50mm. It is assumed that PV module's surface temperature decreases because of increasing distance between solar cells that would give high power generation. Also, short distance between solar cell and frame result in contamination on glass. When considering reduced maximum power caused by contaminant, from that, we can fabricated PV module of lower cost with high performance.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권4호
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• pp.226-234
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• 2004

A rapid Prototyping system that laser-cuts and laminates thick layers can fabricate 3D objects promptly with a variety of materials. Building such a system must consider the surface distortions due to both vertical-cut layers and triangular surfaces. We developed a tangential layer-cutting algorithm by rearranging tangential lines such that they reconstruct 3D surfaces more closely and also constitute smoother laser trajectories. An energy function that reflects the surface-closeness with the tangential lines was formulated and then the energy was minimized by a gradient descent method. Since this simple method tends to cause many local minima for complex 3D objects, we tried to solve this problem by adding a simulated annealing process to the proposed method. To view and manipulate 3D objects, we also implemented a 3D visual environment. Under this environment, experiments on various 3D objects showed that our algorithm effectively approximates 3D surfaces and makes laser-trajectory feasibly smooth.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.54-54
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• 2010

In this study, the correlation between temperature and the gel-content of the module were analyzed through experiments. Amorphous thin-film solar cell used in this experiment has a visible light transmission performance of 10%. In addition, ethylene vinyl acetate(EVA) film and the clear glass have been used for the modulation. The most important process is to laminate the module in the manufacturing process of BIPV(Building integrated photovoltaic) module. Setting parameters of laminator in the lamination process are temperature, pressure and time. Setting conditions significantly affect the durability, watertightness and airtightness of module. The most important factor in the setting parameters is temperature to satisfy the gel-contents. The bottom and top surface temperature of module are measured according to setting temperature of laminator. The results showed $145^{\circ}C$ of max temperature of the bottom surface and $128^{\circ}C$ of max temperature of top surface on the module at the temperature condition of $160^{\circ}C$. And at the another temperature condition of laminator with $150^{\circ}C$, the max temperature do bottom and top are $117^{\circ}C$ and $134^{\circ}C$ respectively. The temperature difference between bottom and top of the module occurred, that is because heat has been blocked by the clear glass and the bottom of the cells absorb the heat from the laminator. In this particular, the temperature difference between setting temperature of the laminator and the surface temperature of the module showed $15^{\circ}C$, because the heat of laminator plate is transferred to the surface of the module and heat is lost at this time. As a results, gel-content showed 94.8%, 88.7% and 81.7% respectively according to the setting temperature $155^{\circ}C$, $150^{\circ}C$ and $145^{\circ}C$ of the laminator. In conclusion, the surface temperature of module increases, the gel-contents is relatively increased. But if the laminator plate temperature is too high, the gel-content shows rather decline in performance. Furthermore, the temperature difference between setting temperature and the surface temperature of the module is affected by laminating machine itself and the temperature of module should be considered when setting the laminator.

• 한국표면공학회지
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• 제29권4호
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• pp.238-252
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• 1996

In order to study the effect of interface oxides on the adhesion strength of the copper/epoxy system, copper foils were immersed in black oxide or brown oxide forming solutions before lamination with epoxy prepregs, and variation of peel strength with the treatment time were investigated. Results showed that peel strength decreased rapidly up to 1 minute of treatment lime and remained constant in the case of the black oxide treated specimens, which was accompanied by the thickening of $Cu_2O$ at the Copper/Epoxy interface during the period. In contrast, peel strength increased rapidly up to 1 minute of treatment time and remained constant in the case of the brown oxide treated specimens, which could be ascribed to the thickening of CuO. Subsequent heat treatments of the Copper/Epoxy laminations at $120^{\circ}C$ in air showed that peel strength remained constant in the case of the black oxide treated specimens but decreased gradually in the case of the brown oxide treated specimens. Following XPS analyses revealed that the latter was possibly caused by the coalescence of CuO at the Copper/Epoxy interface into $Cu_2O$.

• 접착 및 계면
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• 제7권4호
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• pp.53-59
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• 2006

The paper highlights technical advances and introduces recent innovations such as smart curing laminating adhesives for flexible packaging with low migration rates of aromatic isocyanates and amines. Latent reactive one-part systems on the basis of surface deactivated solid isocyanates open up new dimensions for heat setting adhesives and waterborne PU dispersions. The new generation of Purmelt Micro Emission adhesives contains less than 0.1% of MDI monomer, thereby drastically reducing the emission of hazardous isocyanate vapors during processing and setting a significantly improved technical standard in occupational safety. Once again, polyurethane adhesives have demonstrated their unique ability to adapt to new process, product, safety and environmental requirements.