• Journal of the Korea Society of Computer and Information
• /
• v.22 no.3
• /
• pp.97-105
• /
• 2017

This study is the realization study recognizing the Korean gothic printing letter. This study defined the new grapheme by using the connection ingredient and had the graphemes recognized by means of the feature dots of the isolated dot, end dot, 2-line gathering dots, more than 3 lines gathering dots, and classified the characters by means of the arrangement information of the graphemes and the layers that the graphemes form within the characters, and made the character database for the recognition by using them. The layers and the arrangement information of the graphemes consisting in the characters were presumed by using the weight center position information of the graphemes extracted from the characters to recognize and the information of the graphemes obtained by vertically exploring from the weight center of each grapheme, and it recognized the characters by judging and comparing the character groups of the database by means of the information which was secured this way. 350 characters were used for the character recognition test and about 97% recognition result was obtained by recognizing 338 characters.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.35-39
• /
• 2008

In this study, electromechanical properties of carbon nanotube (CNT) thin film on flexible substrates were measured using a micro-tensile machine with functionality of simultaneous measurements of displacement, load and electrical resistance. The CNT thin film of about 100 nm thick was deposited on flexible substrates, polyethylene terephthalate (PET) using spraying and ink-jetting techniques. To investigate the effect of process condition on the electromechanical properties of CNT thin film, sets of CNT samples were fabricated under various heat treatments and microwave process. The microstructures of the CNT thin film before and after tensile test were investigated using Scanning Electron Microscope (SEM), and the failure modes of the CNT thin films were identified to understand their electromechanical behaviors and interaction with the flexible substrates. Based on the experimental results, the use of CNT thin film as flexible electrodes and strain gages is discussed.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.4
• /
• pp.107-113
• /
• 2009

In this paper, we studied of measurement the vibration of natural frequency using optical fiber sensor. The boring bar for measurement of vibration in use optical fiber sensor has the advantage of direct measure for the frequency than accelerometer. Because it deal with output value on electrical signal of optical fiber in physical disturbance when it measures the frequency of vibration. The optical fiber sensor measured the vibration of boring bar by the gap in sensing jig while optical fiber just kept contact with boring bar. A prototype system was composed of jig part with gap and optical system part. In this paper, we found out the possibility to measurement of vibration by the gap in use optical fiber.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.40 no.4
• /
• pp.66-73
• /
• 2008

When coated paperboard is printed, pressed into a groove with a creasing rule and folded, white line cracking occurs along the crease due to intensive mechanical pressure. The cracking will deteriorates product quality and waste resources. Effects of creasing pressure and ink dosage on the foldability of coated board were investigated. It was shown that applying an optimum pressure is important during creasing. When the pressure was too low, the crease formed was not sufficiently deep enough to enable precise folding. When an excess pressure was applied, fiber bonding was destroyed, resulted in unsatisfactory cracking. When the coated board was folded in machine direction (MD), long cracks were formed along MD. When it folded in cross direction (CD), the cracks were shorter and formed perpendicular to CD. Printing promoted cracking due to the decrease in flexibility of coated board. In addition, uneven ink film layer on the coating layer caused worse cracking.

• Journal of Technologic Dentistry
• /
• v.40 no.4
• /
• pp.231-237
• /
• 2018

Purpose: The development of the dental technology industry has digitized the dental process. Definition of Digitalization of Dental Implantation Digitalization is the process of model making and prosthodontic processing using 3D CAD and CAM. Currently, it is becoming popular due to the spread of various devices. However, precision evaluation at this stage is an important factor in precision-based dental procedures. Therefore, in this study, we want to analyze the precision of the processed body made with digital dental machine. Methods: The accuracy of digital dental pore devices was evaluated. Specimens were fabricated with 5 types of 3D printers. The external shape was measured with the prepared specimen. The surface roughness was measured. Results: As a result, precision was excellent in order of EP2 specimen, EP1 specimen, and EA2 specimen. The precision of EP3 specimen and EA1 specimen is not excellent. And the precision of the specimen processed with polymer 3D printer is excellent. The accuracy of LCPS type polymer 3D printers is considered to be excellent. Conclusion : 1. Observation of the shape The 3D printer for LCPS system and the 3D printer for SLM $40{\mu}m$ system were found to be precisely processed. 2. Surface roughness results The LCPS system polymer 3D printer has been shown to have a precise surface.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.5
• /
• pp.245-250
• /
• 2019

In recent years, new technologies such as additive manufacturing have been applied to casting industry, paving new ways to achieve what have traditionally been impossible. In the global market, numerous successful cases of producing cores using additive manufacturing technology have been reported, and new techniques and markets are being developed under governments' support. In Korea, however; cases of applying additive manufacturing to casting are hard to come by, not to mention domestic AM machines and related technologies. Under these circumstances, introduction of additive manufacturing technologies and customized application to domestic casting industry are required. Each chapter of this paper explores topics ranging from the development of AM machine using binder jetting technology among various AM techniques through producing industrial cores to the on-site applications in the foundries.

• Journal of Technologic Dentistry
• /
• v.42 no.4
• /
• pp.341-347
• /
• 2020

Purpose: This study aimed to evaluate the effect of post-curing method on the flexural strength of provisional restorative resins produced by a digital light processing printer. Methods: A total of 20 specimens were produced, with a length of 64 mm, width of 10 mm, and thickness of 3.3 mm using a digital light processing printer. Two types of provisional restorative resins made with different post-curing methods were investigated and divided into conventional and vacuum groups. For the flexural strength test, each group was prepared by each method according to ISO 10477, and the flexural strength was measured with a universal testing machine. For statistical analysis, data were analyzed by independent t-test and Mann-Whitney U test. Results: The flexural strengths of the conventional and vacuum groups were 151.89 MPa and 131.94 MPa, respectively, showing a statistically significant difference (p<0.05). Conclusion: Within the limitation of this study, provisional restorative resins produced with vacuum demonstrated lower flexural strength than those produced with conventional postcuring method.

• Tribology and Lubricants
• /
• v.37 no.6
• /
• pp.213-223
• /
• 2021

Electrochemical mechanical planarization (ECMP) was developed to overcome the shortcomings of conventional chemical mechanical planarization (CMP). Because ECMP technology utilizes electrochemical reactions, it can have a higher efficiency than CMP even under low pressure conditions. Therefore, there is an advantage in that it is possible to reduce dicing and erosions, which are physical defects in semiconductor CMP. This paper summarizes the papers on ECMP published from 2003 to 2021 and analyzes research trends in ECMP technology. First, the material removal mechanisms and the configuration of the ECMP machine are dealt with, and then ECMP research trends are reviewed. For ECMP research trends, electrolyte, processing variables and pads, tribology, modeling, and application studies are investigated. In the past, research on ECMP was focused on basic research for the development of electrolytes, but it has recently developed into research on tribology and process variables and on new processing systems and applications. However, there is still a need to increase the processing efficiency, and to this end, the development of a hybrid ECMP processing method using another energy source is required. In addition, ECMP systems that can respond to the developing metal 3D printing technology must be researched, and ECMP equipment technology using CNC and robot technology must be developed.

• Journal of the Korean Society of Visualization
• /
• v.21 no.1
• /
• pp.110-118
• /
• 2023

Characterizing the extensional rheological properties of non-Newtonian fluids is crucial in many industrial processes, such as inkjet printing, injection molding, and fiber engineering. However, educational institutions and research laboratories with budget constraints have limited access to an expensive commercial extensional rheometer. In this study, we developed a custom-made extensional rheometer using a CO₂ laser cutting machine and 3D printer. Furthermore, we utilized a smartphone with a low-cost microscopic lens for achieving a high spatial resolution of images. The aqueous polyethylene-oxide (PEO) solutions and a Boger fluid were prepared to characterize their extensional properties. A transition from a visco-capillary to an elasto-capillary regime was observed clearly through the developed rheometer. The extensional relaxation time and viscosity of the aqueous PEO solutions with a zero-shear viscosity of over 300 mPa·s could be quantified in the elasto-capillary regime. The extensional properties of the solutions with relatively small zero shear viscosity could be calculated using a smartphone's slow-motion feature with increasing temporal resolution of the images.

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