• Journal of Welding and Joining
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• v.17 no.3
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• pp.71-78
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• 1999

The welded metal bellows is commonly manufactured by welding pairs of washer-shaped discs of thin sheet metal stamped from strip stock in thickness from 0.025 to 0.254 mm. The discs, or diaphragms, are formed with mating circumferential corrugations. In this study, the diaphragms were welded by using a CW Nd: YAG laser to form metal bellows. The bellows was fixed on a jig and compressed axially, while Cu-rings were installed between belows edges for intimate contact of edges. The difference between the inner diameter of bellows and jig shaft causes an eccentricity, while the tolerance between motor shaft and jig shaft causes a wobble type motion. A vision sensor which is based on the optical triangulation was used for seam tracking. An image processing algorithm which can distinguish the image by bellows edge from that by Cu-ring was developed. The geometric relationship which describes the eccentricity and wobble type motion was modeled. The seam tracking using the image processing algorithm and the geometric modeling was performed successfully.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.64-74
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• 2007

Because of the size and environment in the shipbuilding process, the portable type robot is required for the automatic seam tracking. For this reason, the structure of laser sensor should be considered in the initial design step and the coordinate transformation between welding robot and laser sensor, which is joint finder, must be identified exactly and the real time tracking algorithm based on these consideration could be developed. In this research, laser displacement sensor in which its structure is laser beam's vertical projection, is developed to recognize the location of weld joint. In practical applications, however, images of weld joints are often degraded because of the surface specularity or spatter. To overcome the problem, the constrained joint finding algorithm is proposed. In the approach of coordinate conversion rule for the visual feedback control among welding torch, robot body and laser sensor is applied by the same reference point method. In the real time seam tracking algorithms we propose constrained sampling method which uses look ahead distance. The RLS(Recursive Least Square) filter is applied to obtain the smooth tracking path from the sensitive edge data. From the experimental results, we could see the possibility that the developed laser sensor with proposed processing algorithm and real time seam tracking method can be used as a welding under the shipbuilding condition.

• Journal of Broadcast Engineering
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• v.24 no.1
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• pp.142-152
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• 2019

There is growing interest in ultra-high-resolution content that gives a more realistic sense of presence than existing broadcast content. However, in order to provide ultra-high-resolution contents in existing broadcast services, there are limitations in view angle and resolution of the image acquisition device. In order to solve this problem, many researches on stitching, which is an image synthesis method using a plurality of input devices, have been conducted. In this paper, we propose method of dynamic object based video stitching using minimal error seam in order to overcome the temporal invariance degradation of moving objects in the stitching process of horizontally oriented videos.

• Structural Engineering and Mechanics
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• v.49 no.6
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• pp.745-762
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• 2014

As an important part, the connections generally are important for the overall behavior of the structure and the strength and serviceability of the connection should be ensured. This paper presents the mechanical properties of membrane connections in tensioned membrane structure. First, the details of common connections used in the membrane structure are introduced. Then, the common connections including membrane seam, membrane-flexible edge connection and membrane-rigid edge connection are tested and the corresponding failure mechanisms are discussed. Finally, the effects of connection parameters on the connection strength are investigated and proper connection parameters are proposed. The strength reduction factors corresponding to different connection types are proposed, which can be references for the design and analysis of membrane structures.

• Journal of Fashion Business
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• v.27 no.6
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• pp.66-84
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• 2023

Handbags are a part of fashion and while their significance and value are increasing, research on this topic is lacking. This study defines handbags and categorizes the materials used for making handbags, sewing methods, expression techniques, and terminologies related to accessories. A total of 1,743 handbags that were released from the Spring 2020 to Fall 2023, Ready-to-Wear collections by 8 selected brands (Hermes, Dior, Fendi, Chanel, Louis Vuitton, Prada, Gucci, and Alexander McQueen), were analyzed. Out of these, 732 unique designs, excluding those with only color variations, were studied. The most common sewing methods were 'Cut, sewing, and edge painting', 'Cylinder arm sewing', 'Cut, edge painting, and sewing', and 'Inverted seam', in that order. Slim strap designs primarily used the 'Cut, sewing, and edge painting' method, whereas the body, especially with narrow and hard leather, was best suited for the 'Cylinder arm sewing machine'. For expression techniques, the most frequently used methods were 'Quilting', 'Metal Eyelet', 'Embossing', 'Printing', 'Punching', and 'Weaving', respectively. The characteristics of each brand's production methods, expression techniques, and accessories were as follows: First, the exposure of logos and monograms is prominent. Unlike clothing, handbags often prominently feature the brand's logo or monogram. Second, signature quilting is a prominent feature. Quilting effectively conveys the brand's signature style, providing cushioning, volume, and pattern effects. Third, sustainable development is a growing trend. Brands are increasingly applying eco-friendly and socially responsible designs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.7 s.250
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• pp.865-872
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• 2006

High frequency induction welding is widely employed for longitudinal seam welding of small scale tubes and pipes because of its relatively high processing speed and efficiency. This research is aimed at understanding the variables that affect the quality of the high frequency induction welding. The welding variables include the welding frequency, weld speed, V-angle and tube thickness. Temperature distribution of the tube is calculated through three dimensional coupled electromagnetic and thermal FE analysis. The skin and proximity effects are considered in the electromagnetic analysis. The influence of the impeder is also analyzed. The effects of the operating welding variables on the temperature distribution are investigated quantitatively by exhibiting the heat affected zone (HAZ). The results explain the mechanism of significant enhancement of welding efficiency when the impeder is used. The proper welding conditions without the overheated edge are obtained through FE analysis.

• Journal of Welding and Joining
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• v.8 no.2
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• pp.58-69
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• 1990

In conventional arc welding, position error of the weld torch with respect to the weld seam and variation of groove dimension are induced by inaccurate fitup and fixturing. In this study, a vision system has been developed to recognize and compensate the position error and dimensional inaccuracy. The system uses a structured laser light illuminated on the weld groove and perceived by a C.C.D camera. A new algorithm to detect the edge of the reflected laser light is introduced for real time processing. The developed system was applied to arbitarary weld paths with various types of joint in arc welding process. The experimental results show that the proposed system can detect the weld groove parameters within good accuracy and yield good tracking performance.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1137-1140
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• 2005

Automatic welding has been used frequently on pipeline projects. The productivity and reliability are most essential features of the automatic welding system. The mechanized GMAW process is the most widely used welding process and the carriage and band system is most effective welding system for pipeline laying. This application-oriented paper introduces new automatic welding equipment for pipeline construction. It is based on cutting-edge design and practical welding physics to minimize downtime. This paper also describes the control system which was designed and implemented for new automatic welding equipment. The system has the self diagnostic function which facilitates maintenance and repairs, and also has the network function via which the welding task data can be transmitted and the welding process data can be monitored. The laser vision sensor was designed for narrow welding groove in order to implement higher accuracy of seam tracking and fully automatic operation.

• Journal of Korea Multimedia Society
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• v.17 no.10
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• pp.1205-1212
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• 2014

In this paper, we propose a high-quality stitching method of 3D multiple dental CT images. First, a weighted function is generated using the difference of two distance functions that calculate a distance from the nearest edge of an overlapped region to each position. And a blending ratio propagation function for two gradient vectors is parameterized by the difference and magnitude of gradient vectors that is also applied by the weighted function. When the blending ratio is propagated, an improved region growing scheme is proposed to decide the next position and calculate the blending intensity. The proposed method produces a high-quality stitching image. Our method removes the seam artifact caused by the mean intensity difference between images and vignetting effect. And it removes double edges caused by local misalignment. Experimental results showed that the proposed method produced high-quality stitching images for ten patients. Our stitching method could be usefully applied into the stitching of 3D or 2D multiple images.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.71-83
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• 2001

The purpose of this study was to Prove that the medial edge epithelial cells covering the secondary palatal shelves were removed by apoptosis during palatal fusion. 12 mature female rats (Suprague-Dawley) were mated overnight with male rats and sacrificed on days 15.0, 16.5, 16.75, 17.0 of pregnancy. The embryos were removed from the uterus and the heads were embedded in paraffin. The paraffin blocks were sectioned and the sections were undergone H-E staining for general histologic feature and TdT staining for detection of apoptotic cells. The obtained results were as follows. k. In the section of 16.0 and 16.5 day embryos, the palatal shelves were prior to contact and no apoptotic cells wereobserved in the medial edge epithelium. At the initial contact of Palatal shelves, there was a few apoptotic cells in the fusing epithelium. 2. In the 16.75 day embryos, the samples that epithelial seams did not lost there continuity, apoptotic cells were rarely seen at the midline epithelial seam. In contrast, a lot of apoptotic cells were observed at epithelial triangles and the junction between palatal shelves and nasal septum. 3. In the 16,75 day embryos, the samples that epithelial seams lost their continuity and disrupted to epithelial islands, large number, of apoptotic cells were observed at epithelial islands and epithelial triangles. Some apoptotic cells were also observed at the oral, nasal epithelium near the midline. 4. In the 17.0 day embryos, most of epithelial islands were disappeared and mesenchymal confluence was achieved. Apoptotic cells were rarely observed in the mesenchymal tissue which replaced epithelial islands, but there were some apoptotic cells at the epithelial triangles, oral and nasal epithelium. From the results of the study, it was revealed that medial edge epithelial cells of fusing palate were removed by apoptosis. Apoptotic cells were found mainly in the disappearing midline epithelial seam and the oral and nasal epithelial triangles at some late stages of palatal fusion.