• Journal of Institute of Control, Robotics and Systems
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• v.5 no.3
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• pp.353-362
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• 1999

This paper presents a shape reconstruction method for automatic inspection of the solder joints on PCBs using X-ray. Shape reconstruction from X-ray radiographic image has been very important since X-ray equipment was used for improving the reliability of inspection result. For this purpose there have been lots of previous works using tomography, which reconstructs the correct shape, laminography or tomosynthesis, which are very fast algorithm. Latter two methods show outstanding performance in cross-sectional image reconstruction of lead type component, but they are also known to show some fatal limitations to some kinds of components such as BGA, because of shadow effect. Although conventional tomography does not have any shadow effect, the shape of PCB prohibits it from being applied to shape reconstruction of solder joints on PCB. This paper shows that tomography using Iterative Reconstruction Technique(IRT) can be applied to this difficult problem without any limitations. This makes conventional radiographic instrument used for shape reconstruction without shadow effect. This means that the new method makes cost down and shadow-free shape reconstruction. To verify the effectiveness of IRT, we develop three dimensional model of BGA solder ball, make projection model to obtain X-ray projection data. and perform a simulation study of shape reconstruction. To compare the performance of IRT with that of conventional laminography or tomosynthesis, reconstruction data are reorganized and error analysis between the original model are also performed.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.89-99
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• 2006

In this paper a new shape reconstruction method that allows us to construct surface models from very large sets of points is presented. In this method the global domain of interest is divided into smaller domains where the problem can be solved locally. These local solutions of subdivided domains are blended together according to weighting coefficients to obtain a global solution using partition of unity function. The suggested approach gives us considerable flexibility in the choice of local shape functions which depend on the local shape complexity and desired accuracy. At each domain, a quadratic polynomial function is created that fits the points in the domain. If the approximation is not accurate enough, other higher order functions including cubic polynomial function and RBF(Radial Basis Function) are used. This adaptive selection of local shape functions offers robust and efficient solution to a great variety of shape reconstruction problems.

• Honam Mathematical Journal
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• v.36 no.4
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• pp.831-852
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• 2014

The obstacle shape reconstruction problem has been known to be difficult to solve since it is highly nonlinear and severely ill-posed. The use of local or locally supported basis functions for the problem has been addressed for many years. However, to the authors' knowledge, any research report on the proper usage of local or locally supported basis functions for the shape reconstruction has not been appeared in the literature due to many difficulties. The aim of this paper is to introduce the general concepts and methodologies for the proper choice and their implementation of locally supported basis functions through the two-dimensional Helmholtz equation. The implementations are based on the complex nonlinear parameter estimation (CNPE) formula and its robust algorithm developed recently by the authors. The basic concepts and ideas are simple. The derivation of the necessary properties needed for the shape reconstructions are elementary. However, the capturing abilities for the local geometry of the obstacle are superior to those by conventional methods, the trial and errors, due to the proper implementation and the CNPE algorithm. Several numerical experiments are performed to show the power of the proposed method. The fundamental ideas and methodologies described in this paper can be applied to many other shape reconstruction problems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.293-296
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• 2002

This work presents the reconstruction of impact force produced by the collision between two elastic structures. The 2-DOF impactor was designed. The shape control of impact farce using correlations of the dynamic characteristics and impact force history between two elastic structures is accomplished. The effects of the relative motion between impactor and elastic structure on the impact force shape are studied. Reconstruction characteristics of impact force in cantilever beam are reviewed.

• Journal of radiological science and technology
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• v.20 no.1
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• pp.15-20
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• 1997

Unlike conventional CT scan, the helical CT scan uses continuous rotating CT equipment with a slip ring to move the patient's coach at a constant speed while continuously scanning. Slice sensitivity profiles in the Z-position(SSPz) using the conventional X-ray CT have a shape similiar to a rectangular wave, which slightly spreads out into plains below the mountain. However, in the helical CT, with an expansion of the base, the rectangular shape collapses and a mouatain-like shape can be seen. We need to investigate the fellowing factors in helical CT scanning;the ability to scan along the axis of the body, effective slice width, slice shape and the precision of coach velocity, Helical scanning with sprial X-ray track is different from the conventional scanning in terms of the principle of image reconstruction performed. We believe that the problems in helical scanning can be solved by understanding new the special parameters such as the bed moving speed and the interval of image reconstruction.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.76-83
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• 2000

Shape reconstruction is considered as a new technology to be useful and important in many areas such as RPD (Rapid Product Development) and reverse engineering, compared with the conventional design and manufacturing. In shape reconstruction, it becomes possible to reconstruct objects not by their measured shape data but those data extracted from the original shape. The goal of this research is to realize 3D shape construction by showing a possible way to analyze the input image data and reconstruct that original shape. The main 2 steps of the reconstructing process are getting cross-section data from image processing and linking loops between one slice and the next one. And the reconstructed object in this way is compared with the other object using a laser scanner and modelled by an commercial software.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.49-56
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• 2009

In this study, a side collision accident reconstruction using database based on the deformed shape information from the collision test using model cars is suggested. A deformation index and angle index related to the deformed shape is developed to set the database for the collision accident reconstruction algorithm. Two small size RC cars are developed to carry out the side collision test. Several side collision tests according to the velocity and collision angles are performed for establishing the side collision database. A high speed camera with 1000fps is used to capture the motion of the car. A side collision accident reconstruction algorithm is developed and applied to find the collision conditions before the accident occurs. Two collision cases are tested to validate the database and the algorithm. The results obtained by the reconstruction algorithm show good match with original conditions with regard to the velocity and angle.

• Archives of Plastic Surgery
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• v.36 no.6
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• pp.755-760
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• 2009

Purpose: Breast surgeons usually insert tissue expander or implant beneath the subpectoral - subglandular dual plane in breast reconstruction. But sometimes it happens unsatisfactory lower pole fullness, asymmetric inframammary fold and breast shape because there is implant migration due to the pectoralis major muscle contraction and gravity. To solve all the problem like these, we introduce implant breast reconstruction using AlloDerm$^{(R)}$(LifeCell Corp., Branchburg, N.J.) sling. Methods: The AlloDerm$^{(R)}$ sling was used in 13 patients and 18 breasts for implant breast reconstruction. After mastectomy, costal and lower sternal insertion of pectoralis major muscle was detached. Rehydrated AlloDerm$^{(R)}$ was sutured to the chest wall and serratus anterior fascia at the level of inframammary fold downward and to lower border of the pectoralis major muscle upward like crescent shape with tension free technique after implant insertion into the subpectoral - subAlloDerm dual pocket. Results: We make satisfactory lower pole fullness, symmetric inframammary fold and breast shape. In conclusion, patients obtain relatively natural breast shape. There was no complication except one case of capsular contracture and one case of breast cellulitis. Conclusion: Implant breast reconstruction using AlloDerm$^{(R)}$ sling makes easy to get natural breast shape through satisfactory lower pole fullness, symmetric inframammary fold and implant positioning.

• Archives of Plastic Surgery
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• v.46 no.2
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• pp.129-134
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• 2019

Background Nipple-areolar complex (NAC) reconstruction is the final stage of breast reconstruction. Ideal reconstruction of the NAC requires symmetry in position, size, shape, texture, pigmentation, and permanent projection, and although many technical descriptions of NAC reconstruction exist in the medical literature, there is no gold standard technique. The technique devised by the authors is very versatile, with excellent results, and it enables 1-step reconstruction with optimal results in terms of shape and nipple projection. Methods Our technique consists of a combination of modified local flaps and a full-thickness skin graft. Patients were observed for 18 months to estimate the amount of retraction. This procedure was performed in 40 patients, four of them bilaterally. The duration of the follow-up was 30 months. Complications occurred in 10% of patients, and included infections (5%), ischemia (2.5%), and hematoma (2.5%). Results No cases of total nipple necrosis were reported. The NAC shape remained optimal in all cases, with a very small reduction of the vertical and horizontal diameters of the areola, which maintained its designed round shape well, and negligible retraction in the diameter and projection of the nipple. Conclusions The oval technique represents a major step forward, involving a combination of existing techniques, such as the C-V flap and the cutaneous graft, to achieve excellent results regarding areola shape and nipple projection, significantly reducing the cases of nipple ischemia. These results were substantially obtained through subcutaneous equatorial sutures, skin grafting, and flattening of the apexes of the flap.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.5
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• pp.459-464
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• 2015

An on-line quality control of hot steel products is one of the important issues in the steel industry because of cost minimization. In recent years, relative depth information of surface defects is increasingly required for strict quality control. In this paper, a 3D shape reconstruction scheme for defects on a hot steel surface based on a multi-spectral photometric stereo method is proposed. After simultaneously illuminating a hot steel surface by using vertical/horizontal linearly polarized lights of green and blue light sources, the corresponding 4 images are obtained. The photometric stereo method is then applied with the aid of a GPU (Graphic Processing Unit) to reconstruct the shape of the target surface based on these images. The proposed scheme was validated through experiments.