• The Journal of Advanced Prosthodontics
• /
• v.12 no.2
• /
• pp.100-106
• /
• 2020

PURPOSE. The purpose of this in vitro study was to evaluate the fitting accuracy of single crowns made from a novel presintered Co-Cr alloy prepared with a computer-aided design and computer-aided manufacturing (CAD/CAM) technique, as compared with crowns manufactured by other digital and the conventional casting technique. Additionally, the influence of oxide layer on the fitting accuracy of specimens was tested. MATERIALS AND METHODS. A total of 40 test specimens made from Co-Cr alloy were investigated according to the fitting accuracy using a replica technique. Four different methods processing different materials were used for the manufacture of the crown copings (milling of presintered (Ceramill Sintron-group_cer_sin) or rigid alloy (Tizian NEM-group_ti_nem), selective laser melting (Ceramill NPL-group_cer_npl), and casting (Girobond NB-group_gir_nb)). The specimens were adapted to a resin model and the outer surfaces were airborne-particle abraded with aluminum oxide. After the veneering process, the fitting accuracy (absolute marginal discrepancy and internal gap) was evaluated by the replica technique in 2 steps, before removing the oxide layer from the intaglio surface of the crowns, and after removing the layer with aluminum oxide airborne-particle abrasion. Statistical analysis was performed by multifactorial analysis of variance (ANOVA) (α=.05). RESULTS. Mean absolute marginal discrepancy ranged between 20 ㎛ (group_cer_npl for specimens of Ceramill NPL) and 43 ㎛ (group_cer_sin for crowns of Ceramill Sintron) with the oxide layer and between 19 ㎛ and 28 ㎛ without the oxide layer. The internal gap varied between 33 ㎛ (group_ti_nem for test samples of Tizian NEM) and 75 ㎛ (group_gir_nb for the base material Girobond NB) with the oxide layer and between 30 ㎛ and 76 ㎛ without the oxide layer. The absolute marginal discrepancy and the internal gap were significantly influenced by the fabrication method used (P<.05). CONCLUSION. Different manufacturing techniques had a significant influence on the fitting accuracy of single crowns made from Co-Cr alloys. However, all tested crowns showed a clinically acceptable absolute marginal discrepancy and internal gap with and without oxide layer and could be recommended under clinical considerations. Especially, the new system Ceramill Sintron showed acceptable values of fitting accuracy so it can be suggested in routine clinical work.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.1
• /
• pp.50-56
• /
• 2010

This paper presents a new design algorithm for piece-removing dynamical system, based on 6-Sigma DMADOV technique using ARIZ and Brainstorming. Our design target is the piece-removing system installed on a mobile platform of bead-grinding equipment. The 6-Sigma DMADOV technique guides us design process according to 6 steps, i.e., Define - Measure - Analyze - Design - Optimize - Verify. A Design strategy to reduce the weight of piece-removing dynamical system will be explored by using ARIZ, i.e.,(the abbreviation of Algorithm for Inventive Problem Solving in Russian). The ARIZ will result in a final solution that the height and angle control parts for a cutting tool should be replaced by a kinematical approach, rather than complicated mechatronic approach(using motors). The Optimize step is composed of two sub-steps: (i) Generating process for obtaining several ideas of piece-removing system by using Brainstorming technique, satisfying the final solution derived from the Design step using ARIZ, and (ii) Optimizing process for selecting the most optimal idea of piece-removing system by using Pugh's matrix from the viewpoints of weight, cost and accuracy. The laststep of Verify has shown that the final design obtained by the 6-Sigma DMADOV technique with ARIZ & Brainstormingcan improve an initial design with design requirements satisfied. In this paper, we have shown that ARIZ and Brainstorming can be cooperatively merged into 6-Sigma DMADOV to give us both a formulatedproblem-solving approach and diverse candidate solutions(or ideas) without trial-and-error efforts.

• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.1
• /
• pp.67-76
• /
• 2020

With the evolution of the computer-aided design/computer-aided manufacturing (CAD/CAM) technology, the intraoral scanners are playing an increasingly important role, as they are the first step towards a completely digital workflow. The CAD/CAM double scanning technique has been used to transfer the information from provisional restorations to definitive restorations. In this case, a 67-year-old male with esthetically compromised anterior teeth, generalized severe attrition of teeth, and reduced vertical dimension was treated with full mouth rehabilitation including a re-establishment of the lost vertical dimension of occlusion assisted by the crown lengthening procedure. The provisional restorations were fabricated using an intraoral scanner and the CAD/CAM double scanning technique. After the period of adaption, the definitive monolithic zirconia restorations were delivered. The CAD/CAM double scanning technique successfully transferred the occlusal and morphological characteristics, obtained from the provisional restorations, to the definitive restorations.

• Fire Protection Technology
• /
• s.28
• /
• pp.48-54
• /
• 2000

The technique detects radiant energy form a flaming fire of fuels contained carbonaceous material can be applied to fast growing fires. This technique applied detectors are ultimately effective when early detecting fire alarm system is required or the smoke and heat detectors can not applied. In Korea Fire regulation, a flame detector should be install in case that the installation height is higher than 20[m], chemical plant, hangar refinery. Therefore it is really necessary that a flame detector has to be developed as soon as possible. With foundation technique of flame detector, ideal sensing element and stable circuit design, a trial UV flame detector is manufactured. The stable and reliable technique of flame detector is established through the repeateed perfomance test and modification. An early detecting fire alarm device is developed through the modification, supplement of the structure and circuit. Results of the R & D for the manufacture of an excellent flame detecting device is carried out with the establishment of technique for the mass production and the qualified manufacturing process.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.05a
• /
• pp.93-96
• /
• 2001

Structural polymer composites are susceptible to damage in the form of cracks, which form deep within the structure where detection is difficult and repair is almost impossible. A recent methodology for the damage repair of polymer composites using the self-healing technique is reported. The polymerization of the healing agent is triggered by contact with an embedded catalyst, being necessary to damage repair of polymer composites. For this purpose, the self-healing concept is introduced and the manufacturing process of microcapsule with the healing agent is briefly described. The polymerization between the healing agent and the catalyst is verified by the use of ESEM and IR spectroscopy. Finally the efficiency of the self-healing technique is investigated by measuring the critical load of TDCB specimen.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.122-127
• /
• 2001

Lasting machines for shoe manufacturing are continuously developed with the aid of automation and Computer Aided Manufacturing (CAM). Although automation and CAM techniques have tremendously reduced the labor in shoe manufacturing field, there still remain some parts manufactured by experts. In order to enhance the capability and efficiency of machines for labor-free shoe manufacturing, CAD data of a shoe last is indispensable. While CAD datarization takes the fundamental role in the shoe design as well as the shoe manufacturing, there has been little research for the CAD datarization of a shoe last. In this paper, a new procedure for CAD datarization of a shoe last using finite element patches is proposed and some data for the control part of the shoe lasting machine are extracted and interpolated from the CAD data. The outer line of a shoe-last sole is interpolated by a tension spline method and bonding lines are extracted from the shoe CAD data. Finally, initial setting data for the lasting machine are extracted from the last CAD data and initial setup parts of the lasting machine.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.1 no.1
• /
• pp.79-88
• /
• 2002

High speed machining system have been used in industrial because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. Therefore this study proposed to decide best manufacturing cutting condition for surface roughness and rapid manufacturing tune by using computer Image processing system and 3D modelling. Until the 16,000 rpm, the surface roughness is decreased rapidly, but it is not over that. The 22,000 rpm is the spindle speed with the optimum surface in the high speed end-milling. In the case of the feed rate with 2,000 mm/mm and 8,000 mm/mm, the surface roughness is better than 4,000 mm/min and 6,000 mm/min. By using the 3D modelling, it is effectively represented shape characteristics of working surface m high speed end-milling.

• Journal of Computational Design and Engineering
• /
• v.2 no.4
• /
• pp.248-252
• /
• 2015

Currently composite manufacturing process, such as linear friction welding plus NC machining, is the main method for the manufacturing and repairing of complex parts with integrated structure. Due to different datum position and inevitable distortion from different processes, it is important to ensure sufficient machining allowance for complex parts during the NC machining process. In this paper, a workpiece localization approach for machining allowance optimization of complex parts based on CMM inspection is developed. This technique concerns an alignment process to ensure sufficient stock allowance for the single parts as well as the whole integrated parts. The mathematical model of the constrained alignment is firstly established, and then the symmetric block solution strategy is proposed to solve the optimization model. Experiment result shows that the approach is appropriate and feasible to distribute the machining allowance for the single and whole parts for adaptive machining of complex parts.

• Journal of Fashion Business
• /
• v.1 no.2
• /
• pp.46-54
• /
• 1997

The purpose of this study is to understand women's wear manufacturing industries. First, the study was to investigate the present production systems and how much the automatic facility are by comparing them. This study enhanced more efficient, stable, and suitable work line. This intern will direct the way in which automatic facilities will be created. Second, through this study on the general character of the inspectors, the ratio of impaired goods, and the reasons for unsatisfactory goods, I intended to find out a way to decrease the impaired goods and to produce competitive and high quality goods. The results of the survey can be summarized as follows; 1. The result of the research on the automatic industrial facilities shows that the majority of the factories (77.4%) are 40% below the automatic facility rate. The reasons for this according to order are that was a deficit in money, no reason for expensive machines, and lack of the technique and the number of workers required to handle the machines. 2. At this time, the most required equipments are shown according to its importance; automatic sewing machine, automatic cutting machine, automatic spreading machine, and finishing & pressing machine. So in the women's wear manufacturing industries, they think that they need more automatic cutting machine, automatic spreading machine in the cutting field rather than high price automatic machine in the sewing field such as pattern former, pocket welting, automatic sleeve connecting machine and automatic label connecting machine. 3. The result of the research in the goods quality shows that the average impaired rate is 12.7% at the first inspection. In addition the average rate for complete impaired rate is 1.52%. The line system shows that it has a impaired rate that is double the rate of the pair system. Because of this, the industries plan to combine the line system and pair system to create an improved and suitable production system which can boost the quality and productivity of the goods. 4. The fabric is the main point of the impaired goods. The factors of the impaired goods in manufacturing are the lack of mental abilities of the worker, impaired fabrics and a lack of cooperation in the working system. Furthermore, there is a lack of technique for new material. 5. To prohibit impaired goods in manufacturing, there need to be a way to educate the workers and to enhance the workers' mind on the productive goods. Also there need to increase in the investments of automatic production machines. Finally there need to be a standardized working line. Therefore, there need to be an improvement on the management of the production of goods, the development of technique and an increase in the education for the workers, with this there will be a decrease in impaired goods, and an increase in better quality of goods to enforce the domestic apparel industries.

• Journal of the Korea Furniture Society
• /
• v.21 no.2
• /
• pp.97-110
• /
• 2010

As the contemporary lifestyle has changed and the time to enjoy hobbies is increased, people prefer the DIY furniture that can be used at homes by manufacturing their own unique furnitures. Especially, the architecture of our country handed down traditionally or the setting-up technique used in furnitures are the techniques to maintain firmness even after long time passes by. Accordingly, in order to supply a firm setting-up technique mostly used by craftsman in the manufacture of DIY furniture and to apply this easily, a web site and 3D program system are required. In order to do so, it is important to prepare the system of setting-up that can be followed easily first by classifying the difficulty of setting-up that the general public can follow easily without having difficulties among the types of setting-up. Therefore, this study has performed a systematic arrangement by the order of difficulty for the types of setting-up that are investigated and arranged to set the purpose as presenting materials that are helpful so the furnitures using setting-up can be manufactured even in the manufacture of general DIY furnitures. Accordingly, the investigated results of setting-up difficulty are applied in the order of difficulty to a 3D program and as users select the suitable setting-up for their own standard, it is expected to be utilized in DIY furnitures that are manufactured directly.