• 한국기계가공학회지
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• 제15권4호
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• pp.73-82
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• 2016

Recently, automobile industries have been developing many structural automotive parts made of thin, high-strength steel strips to produce safer and more environmentally friendly cars. The roll forming process has been considered one of the most efficient processes in manufacturing high-strength steel parts because it is a high-speed process that forms sheets in increments. However, most automotive parts vary longitudinally in their cross-sections. Therefore, it is difficult to apply the roll forming process to automotive parts made of high-strength steel. A variable section roll forming process has been proposed in recent studies. The rotational axes of the forming rolls are fixed, and the forming rolls have three-dimensional shape. As such, the cross-section of the part varies linearly along its length, and the angle between the bend line and longitudinal axis is less than 1 degree. Thus, the rate of cross-sectional variation along the length is relatively small. In this study, the rate of cross-sectional change along the length of a forming roll has been increased. Moreover, the angle between the bend line and longitudinal axis has been increased up to 15 degrees. The variable sections of the forming rolls have been designed for high strength steel parts with a symmetric u-type cross-section that varies linearly and symmetrically along the longitudinal axis.

• International Journal of Automotive Technology
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• 제4권4호
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• pp.193-201
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• 2003

The problem of brake judder is typically caused by defects of quality manufacturing. DFSS (Design for six sigma) is a design process for quality improvement. DFSS will result in more improved but less expensive quality products. This paper presents an implementation of DFSS for quality improvement of the brake judder of heavy-duty trucks. Carrying out 5 steps of DFSS, the major reasons for defects of quality are found. The numerical approximation of the brake system is derived by means of the response surface method. Its quality for brake judder is improved by using the sigma based robust design methodology. Results are compared between the conventional deterministic optimal design and the proposed sigma based robust design. The proposed one shows that manufacturing cost may increase as the quality level increase. The proposed one, however, is more economical in aspect of the overall cost since the probability of failure dramatically goes down.

• International Journal of Automotive Technology
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• 제7권6호
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• pp.721-728
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• 2006

This paper is concerned with development of digital assembly cell. Automotive industries, try to find out new welding technologies to replace the existing spot welding which is not appropriate anymore. Because of many advantages like good accessibility, welding quality and fast welding speed, laser welding seems the most appropriate solution for automobile manufactures. To apply this technology to welding of car body, experiments must be conducted according to material, geometry and layer in welding area. Based on the data of these experiments, the laser welding process and the quality of stitches are identified. And then, the comparison between the requirements of welding and the potential of equipments allows selecting the best equipments. By using the digital manufacturing, the configurations of laser welding cell are carried out. After all, the optimal laser welding cell is chosen by the evaluation of alternative cells with technical and organizational criteria.

• 한국기계가공학회지
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• 제15권1호
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• pp.103-109
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• 2016

The performance of a multi-head, computerized combination scaling system to automatically identify a group of agricultural products having a total weight within the target range has been optimized to reduce the package cycle time of the merchandise. First, the structure of the scale was modified to enable faster measurement by enhancing the dynamic stability during the process. Second, the high frequency noise in the measured signal was eliminated by a high frequency filter to provide more accurate weight data. Finally, the algorithm to identify a group of products with a total weight within the target range was modified to enable a user to select an optimal number of scales. According to the experimental verifications, this modified system reduced the package cycle time significantly and also was accurate in measuring the total weight of the selected products.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 자동차부품 제작기술의 진보
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• pp.75-86
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• 1996

Three-Dimensional finite element analysis is performed using PAM-STAMP for design evaluation of automotive back door inner panel die. Gravity process by blanks own weight, binder-wrap process, and drawing process in the forming operations are sequentially simulated with Virtual Manufacturing Method. The most valuable result in this research is that 3-D FEM analysis can be applied to the design evaluation of draw die in the die try-out, though effects of mesh size and drawbead resistance force on the numerical accuracy are much sensitive. For the intensive application to draw-die design and try-out, the experimental know-hows about the forming variables such as friction coefficient, punch velocity, drawbead force, etc are necessary.

• 한국기계가공학회지
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• 제15권5호
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• pp.137-144
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• 2016

This paper aims to ensure describe the a spring-back prevention technique for improving shape fixability by using an ultra-high strength steel sheet with 980 MPa to develop a lightweight seat rail parts. Ultra-high strength steel gives a potential for considerable weight reduction and a cost-effective way to produce energy efficient vehicles. The influence of a spring-back of seat rail parts on the shape fixability in forming processes was investigated to be solved by an adjustment of the appropriate tool design and process parameters. The computed results for improving shape fixability were in good agreement with the experimental results.

• 한국기계가공학회지
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• 제17권4호
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• pp.47-54
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• 2018

These days, the aerospace industry uses larger machining parts and assembly parts than those in the past. The assembly machines also show the same trend. This study is concerned with the alignment measuring apparatus for the B-axis of a separated multi-axis machine. The alignment measuring apparatus is widely installed for assembly machines in the aircraft assembly process. The alignment measuring apparatus consists of a swivel part and a measuring part. This is a new conceptual idea under patent. All elements of the alignment measuring apparatus are analyzed with the FEM. The analyzed result shows that the alignment measuring apparatus is high in accuracy with stability and steady deformation.

• 소성∙가공
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• 제6권2호
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• pp.152-160
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• 1997

Three-Dimensional finite element analysis is performed using PAM-STAMP for design evaluation of automotive back door inner panel die. Gravity process by blank own weigth, binder-wrap process, and drawing process in the forming operations are sequentially simulated with Virtual Manufacturing Method. The most valuable result in this research is that 3-D FEM analysis can be applied to the design evaluation of draw dies in the die try-out, though effects of mesh size and drawbead resistance force on the try-out, the experimental knowhows about the forming variables such as friction coefficient punch velocity, drawbead force, etc are necessary.

• 반도체디스플레이기술학회지
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• 제8권2호
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• pp.15-21
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• 2009

Atmospheric pressure plasma equipment was successfully applied to the flip chip BGA manufacturing process to improve the uniformity of flux printing process. The problem was characterized as shrinkage of the printed flux layer due to insufficient surface energy of the flip chip BGA substrate. To improve the hydrophilic characteristics of the flip chip BGA substrate, remote DBD type atmospheric pressure plasma equipment was developed and adapted to the flux print process. The equipment enhanced the surface energy of the substrate to reasonable level and made the flux be distributed over the entire flip chip BGA substrate uniformly. This research was the first adaptation of the atmospheric pressure plasma equipment to the flip chip BGA manufacturing process and a lot of possible applications are supposed to be extended to other PCB manufacturing processes such as organic cleaning, etc.

• 한국기계가공학회지
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• 제17권2호
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• pp.15-21
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• 2018

In this paper, a detection and warning system is proposed for the remaining kids in a school bus. For detecting the remaining kids, an ultrasonic sensor is used. The basic experiments of the ultrasonic sensor are performed, and a modified ultrasonic sensor is proposed. Also, the appropriate location of the ultrasonic sensor is proposed by considering various sitting positions. Based on the above kid detection system, a warning algorithm is designed. Using the above detection and warning system, experiments are performed. From the experimental results, it is found that the proposed system, based on the modified ultrasonic sensor, can detect the remaining kids in a school bus. The proposed system can also give an appropriate warning signal.