• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.152-159
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• 2000

In piercing operation for small hole in very thin plate, micro burrs are formed. The micro burr is very difficult to remove because the thin plate is to be deformed during deburring and deteriorate accuracy. As a first step to remove the micro burrs effectively, the burr must be measured accurately as much as possible. For most micro burrs are so small as less than 10$\mu\textrm{m}$, it is very difficult to measure. Several methods are reviewed to measure the micro burr formed in piercing operation from very thin plate with thickness less than 0.1mm. Also the effective deburring methods are reviewed. Barreling ultrasonic and chemical deburring methods are performed and the results are compared.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.22-32
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• 1998

This paper describes a research work of developing a computer-aided design of irregularly shaped-sheet metal product with bending and piercing operation for progressive working. An approach to the CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of five main modules, which are input and shape treatment, flat pattern-layout, production feasibility check, blank-layout, and strip-layout module. Based on knowledge-based rules, the system is designed by considering several factors, such as radius and angle of bend, material and thickness of product, complexities of blank geometry and punch profile, and availability of press. This system is capable of unfolding a formed sheet metal part to give flat pattern and automatically account for the adjustment of bend allowances to match tooling requirements by checking dimensions and the best utilization ratio of blank-layout within bending production feasibility area which is beyond ${\pm}30^{\circ}$ degrees intersecting angle between grain flow and bending edge line and which is suitable to progressive bending operation. Also the strip-layout drawing generated by a bending and a piercing operation according to punch profiles divided into automatically for external area of irregularly shaped-sheet metal product is displayed in graphic forms.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.171-179
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• 1997

This paper describes a nesting system of a computer-aided design of blanking and piercing for irregularly shaped sheet metal products. An approach to the system is based on knowledge-based rules. A nesting system is designed by considering several factors, such as utilization ratio which minimises the scrab for single or pairwise operation, bridge width, grain orientation and design requirements which maximise the strength of the part when subsequent bending is involve. Therefore this system which was implemented blank layout and strip layout module can carry out a nesting with a best utilization and a process planning for irregular shaped sheet metal products in single or pairwise operation and generate the blank layout and strip layout in graphic forms. Knowledges for a nesting and a process planning are extracted from plasticity theories, relevant references and empirical know-hows of experts in blanking industries. This provides its efficiency and effectiveness for nesting irregularly shaped sheet metal products.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.7
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• pp.971-979
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• 1999

The experiment was conducted on five different kinds of fabrics dyed with loess. The sewability of fabrics dyed with loess by measuring the maximum needle piercing forces(MPF) through fabrics has been studied, MPF measurement using tensile tester was done 60 times for each fabrics at fixed low speed of 300mm/min. The nature of the loess on the dyed fabrics was physically jammed betweenthe fibers or adhered to the surface of fibers in the form of the fine particles so that the MPF through fabrics increases extremely in proportion to the increase of loess uptake and the plying number of fabrics dyed with loess. This results indicate that the MPF through fabrics is affected by mean value of the coefficient of friction on the surface of fabric(MIU) and cloth cover factor(Kc) in this experiment. Fabric was finished with softner to decrease the MPF during sewing operation, The MPF through softner finished fabric was decreased remarkably.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.174-182
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• 1998

This paper describes a research work of developing a computer-aided design and machining of irregular shaped-sheet metal product for blanking or piercing operation. An approach to the CAD/CAM system is based on the knowledge-based rules. Knowledge for the CAD/CAM system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules, which are input and shape treatment, flat pattern-layout, production feasibility check, blank-layout, strip-layout, die-layout, data conversion, modelling, and post-processor module. Based on knowledge-based rules, the system is designed by considering several factors, such as material and thickness of product, complexities of blank geometry and punch profile, diameter and material of a wire, and availability of press. This system is capable of generating NC data automatically according to drawings of die-layout module. Results which are carried out in each module will provide efficiencies to the designer and the manufacturer of blanking or piercing die in this field.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.155-159
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• 1998

This paper describes a research work of developing a computer-aided design and manufacturing (CAD-CAM) of irregular shaped sheet metal product for blanking or piercing and bending operation. An approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated form plasticity theories, experimental results and the empirical knowledge of field experts. This system has been written in AutoLIST on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules. the system is designed by considering several factors, such as material and thickness of product, complexities of blank geometry and punch profile, diameter and material of a wire, and availability of press. This system is capable of unfolding a formed sheet metal to give flat pattern and automatically account for the adjustment of bending allowances to match tooling requirements by checking dimensions and generating NC data automatically according to drawings of die-layout module. Results carried out in each module will provide efficiencies to the designer and the manufacture of blanking or piercing and bending die in this field.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.554-561
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• 1998

This paper describes a research work of developing a computer-aided design of lead frame semicon-ductor with piercing operation which is very precise for progressive working. An approach to the sys-tem is based on to knowledge-based rules. Knowledge for the system is formulated from plasticity theories experimental results and the empirical knowledge of field experts. This system has been writ-ten using AutoLISP to AutoCAD on a personal computer and is composed of three main modules which are input and shape treatment production feasibility check and strip-layout module. Based on the knowledge-based rules the system is designed by considering several factors such as material and thickness of product complexities of blank geometry and punch profile, and availability of press. Also strip-layout drawing generated by piercing operation according to punch profiles considered V-notch dimple. pad chamfer spank cavity punch camber and cross bow of lead frame is displayed in graphic forms. This system can be used by a novice who may not have any knowledge of tool design and will invrease efficiencies to the designer in this field.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.76-84
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• 1997

A process sequence in precision press forming of electrnic components is investigated by the finite element method. Aperture, a key component of electronic gun, is formed through a sequence of about 15 operation, among which the beading & bending, the first piercing, the first coining, and the second coining operations are expected to be most critical in view of industrial experts opinions. Thus, the analysis per- formed by a commercial code MARC focuses on the three operations, and comparisons are made between the results of the analysis and the measurements of experimental forming of the component.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.124-133
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• 1998

This paper describes a research work of developing a computer-aided design of blanking and piercing for irregular-shaped sheet metal products. An approach to the development of compact and practical CAB system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer. Based on knowledge-based rules, the system, STRT-DES, is designed by considering several factors, such as complexities of blank geometry and punch profile, availability of press equipment and standard parts, utilization ratio which minimizes the scrap in a single or a pairwise operation, bridge width, grain orientation and design requirements which maximize the strength of the part when subsequent bending is involved. This system checks a forming feasibility with both internal and external features, a dimension of blanked hole, and a corner and a fillet radius for irregualrly shaped sheet metal products. Therefore this system can carry out a die design for each process which is obtained from results of an automated blank layout drawing with a best utilization ratio for irregular shape of product that was successful in production feasibility check module and those of an automated strip layout drawing and generate part drawings and the assembly drawing of die set in graphic forms.

• Archives of Craniofacial Surgery
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• v.17 no.1
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• pp.5-8
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• 2016

Background: Lobular keloid appears to be a consequence of hypertrophic inflammation secondary to ear piercings performed under unsterile conditions. We wish to understand the pathogenesis of lobular keloids and report operative outcomes with a literature review. Methods: A retrospective review identified 40 cases of lobular keloids between January, 2005 and December, 2010. Patient records were reviewed for preclinical factors such as presence of inflammation after ear piercing prior to keloid development, surgical management, and histopathologic correlation to recurrence. Results: The operation had been performed by surgical core extirpation or simple excision, postoperative lobular compression, and scar ointments. Perivascular infiltration was noted in intra- and extra-keloid tissue in 70% of patients. The postoperative recurrence rate was 10%, and most of the patients satisfied with treatment outcomes. Conclusion: Histological perivascular inflammation is a prominent feature of lobular keloids. Proper surgical treatment, adjuvant treatments, and persistent follow-up observation were sufficient in maintaining a relatively low rates of recurrence.