• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.92-95
• /
• 2011

In manufacturing optical fibers, the process starts with the glass fiber drawing from the heated and softened silica preform in the furnace, and the freshly drawn glass fiber is still at high temperature when it leaves the glass fiber drawing furnace. It is necessary to cool down the glass fiber to the ambient temperature before it then enters the fiber coating applicator, since the hot glass fiber is known to cause several technical difficulties in achieving high quality fiber coating. As the fiber drawing speed keeps increasing, a current manufacturing of optical fibers requires a dedicated cooling unit with helium gas injection. A series of three-dimensional flow and heat transfer computations are carried out to investigate the effectiveness of fiber cooling in the fiber cooling unit. The glass fiber cooling unit is simplified into the long cylindrical enclosure at which the hot glass fiber passes through at high speed, and the helium is being supplied through several injection slots of rectangular shape along the cooling unit. This study presents and discusses the effects of helium injection rates on the glass fiber cooling rates.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.8
• /
• pp.2213-2221
• /
• 1999

A line segment has a symmetrical property about its midpoint. With this symmetrical property for a line segment we have proposed a variant of Bresenham's line drawing algorithm that selects two pixels at the same time. It implies that bi-directional line drawing toward the midpoint of line segment from each-end be possible. Besiders, it can select two pixels using only one decision parameter, instead of two different parameters for each pixel. We also present a theoretical proof for the correctness of such a selection. Thus, we can reduce the time of generating line segment by approximately less than 5% compared to the Bresenham's method. Also, our experimental results show that the shape of line segment generated by the proposed approach is the exactly same as that of Bresenham's method.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.5
• /
• pp.979-983
• /
• 2007

In this thesis, a strip layout drawing of LCD S/C (shield case) was prepared. In the press die, strip layout drawing is a major factor that decides the mass production of a product. The 3D CAD/CAM system was applied for the easy correction of the interference factor with other parts to be mounted. The material use ratio was enhanced to 60.17% by optimizing the blank layout and strip layout in double width array. Furthermore, the flatness of the product was made to fit the requirements by adding the bidding process intensively on the notching part where the occurrence of the change in shape is expected owing to the thin material. For the 3D CAD/CAM software, Unigraphics NX3.0 was used. The strip layout drawing was prepared in 12 processes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.374-377
• /
• 2008

Magnesium alloy sheets are usually formed at temperatures between $150^{\circ}C$and $300^{\circ}C$ because of their poor formability at room temperature. In the present study, the formability of AZ31B magnesium alloy sheets was investigated by the analytical and experimental approaches. First, tensile tests and the limit dome height test were carried out at elevated temperatures to get the mechanical properties and forming limit diagram, respectively. And then deep drawing of cross shaped die was tried to get the minimum corner radius and forming limit at specific temperature. Blank shape, punch velocity, minimum corner radius, fillet size, etc, were determined by finite element analysis physical try-outs. Especially, optimum punch and die temperature were suggested through the temperature-deformation analysis using Pam-stamp.

• Journal of KIBIM
• /
• v.11 no.4
• /
• pp.42-52
• /
• 2021

Paneling building facades is one of the essential procedures in building construction. Traditionally, it has been an easy task of simply projecting paneling patterns drawn in drawing boards onto 3d building facades. However, as many organic or curved building shapes are designed and constructed in modern architectural practices, the traditional one-to-one projection is becoming obsolete for the building types of the kind. That is primarily because of the geometrical discrepancies between 2d drawing boards and 3d curved building surfaces. In addition, curved compound surfaces are often utilized to accommodate the complicated spatial programs, building codes, and zoning regulations or to achieve harmonious geometrical relationships with neighboring buildings in highly developed urban contexts. The use of the compound surface apparently makes the traditional paneling pattern projection more challenging. Various mapping technics have been introduced to deal with the inabilities of the projection methods for curved facades. The mapping methods translate geometries on a 2d surface into a 3d building façade at the same topological locations rather than relying on Euclidean or Affine projection. However, due to the intrinsic differences of the planar 2d and curved 3d surfaces, the mapping often comes with noticeable distortions of the paneling patterns. Thus, this paper proposes a practical method of drawing paneling patterns directly on a curved compound surface utilizing Geodesic, which is faithful to any curved surface, to minimize unnecessary distortions.

• Design & Manufacturing
• /
• v.6 no.1
• /
• pp.34-38
• /
• 2012

Test work is the press die branch at The Korea-China-Japan Grand Prize Contest. This study focuses on strip layout design for test work. A comparison is drawn between product shape and blank deployment line. During the forming analysis of the whole product, shape part of the total forming process is analyzed. As for forming part and flange deployment, forming analysis is carried out in part during the mid process. Material utilization is 42.6 percent and strip layout design is completed in 14 processes that are comprised of hourglass, slotting, embossing, drawing and trimming.

• Journal of the Korean Professional Engineers Association
• /
• v.27 no.3
• /
• pp.121-131
• /
• 1994

It is very difficult to partially describe the hull shape made up of 3-dimensional free form surface. With computerizing skill in ship design, the geometric modeling technique has been developed. In hull shape modeling, the blending technique has not yet been adapted to the hull shape surface has a variable curvature. By adapting the blend surface, small surface on drawing plane is to be softly blended with given hull surface and a projecting part. This study has adapted to the ship design one of the blending methods by which offsets data of the blend surface can be obtained by the input of blend radius on two base surfaces.

• Transactions of Materials Processing
• /
• v.10 no.1
• /
• pp.15-22
• /
• 2001

The sensitivity method has been utilized to find initial blank shapes which transform into desired shapes after forming. From the information of die shapes, target shape and material properties, the corresponding initial blank which gives final shape after deformation has been found. Drawings of a trapezoidal cup, a cross-shaped cup and an oil pan have been chosen as the examples. At every case the optimal blank shape has been obtained only a few times of modification without any predetermined deformation path. With the predicted optimal blank, both computer simulation and experiment are performed. Excellent agreements are recognized between simulation and experiment at every cases Through the investigation, the sensitivity method is found to be effective in obtaining optimal blank shapes in drawing of complex shapes.

• Transactions of Materials Processing
• /
• v.26 no.2
• /
• pp.79-86
• /
• 2017

In this study, the sheet metal forming process of the brake chamber head, which had a complex shape compared to the conventional head part, was investigated using finite element (FE) analysis. In order to prevent the forming failures such as necking and fracture, the multi-stage forming process was introduced. The forming process consisted of three steps: (1) first drawing, (2) second drawing, (3) final forming. Experimental and FE simulated results of the brake chamber head were compared, and the results showed that the required characteristics of the straightness and the wall thickness at each location were satisfied.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.174-177
• /
• 2001

The automated computer-aided drafting technique is attempted for drawing process pictures of axisymmetric solid forgings which are mainly used in automobile industry. For this study basic concepts to draw the shape of an element are described and applied to the 2-dimensional and 3-dimensional modeling of forged parts. 2-dimensional display of process pictures is developed by using AutoLISP language in AutoCAD software of a drafting technique and 3-dimensional view of process pictures is based on the UG/open API and UG/open GRIP languages of Unigraphics software. Testing the developed program to forging of bolts and ballstuds, it was shown to give good results to be applicable in forging industry.