• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.215-218
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• 1991

In designing the Machine element, most or part drawings are composed of basic entities. The basic entitles are classified into groups in order to enhance the drawing efficiency of computer aided design system based on GT concept. This paper deals with the generalization of handling drawing procedures which can cover the standard parts and the basic constitutional part of mold base.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1871-1876
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• 2004

We demonstrate a novel fabrication technology for the microneedle array that can be used in the medical test field, which is transdermal drug delivery and blood analyte sampling. Previous researchers have used silicon-processed micromachining, a reactive ion etching, and molding techniques for the fabrication of microneedle array. However, these fabrication techniques have somewhat limitations apply to the microneedle array fabrication according to its application. Inclined LIGA process is suggested to overcome these problems. This process provides easier, sharper and longer out-of-plane microneedle array structure than conventional silicon-processed fabrication method did. Additionally, because of the advantage of the LIGA process based on mold fabrication for mass production, the polymer, PMMA(PolyMethylMethAcrylate), based microneedle array is useful as the mold base of nickel electroplating process; on the other hand, silicon-processed microneedle array is used in itself. In this research, we fabricate different types of out-of-plane microneedle array, which have different shape of tip, base and hole structure, using the inclined LIGA process. The fabricated microneedles have proper mechanical strength, height and sharpness to puncture human hand epidermis or dermis with less pain and without needle tip break during penetrating the skin.

• Design & Manufacturing
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• v.14 no.3
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• pp.8-16
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• 2020

In this study, the vibration signal of the mold was measured and analyzed to monitoring the process time and characteristics during injection molding. A 5 inch light guide plate mold was used to injection molding and the vibration signal was measured by MPU6050 acceleration sensor module attached the surface of fixed mold base. Conditions except for injection speed and packing pressure were set to the same value and the change of the vibration signal of the mold according to injection speed and packing pressure was analyzed. As a result, the vibration signal had a large change at three points: "Injection start", "V/P switchover", and "Packing end". The time difference between "injection start" and "V/P switchover" means the injection time in the injection molding process, and the time difference between "V/P switchover" and "Packing end" means the packing time. When the injection time and packing time obtained from the vibration signal of the mold are compared with the time recorded in the injection molding machine, the error of the injection time was 2.19±0.69% and the error of the packing time was 1.39±0.83%, which was the same level as the actual value. Additionally, the amplitude at the time of "injection start" increased as the injection speed increased. In "V/P switchover", the amplitude tended to be proportional to the pressure difference between the maximum injection pressure and the packing pressure and the amplitude at the "packing end" tended to the pressure difference between the packing pressure and the back pressure. Therefore, based on the result of this study, the injection time and packing time of each cycle can be monitored by measuring the vibration signal of the mold. Also, it was confirmed that the level and trend of process variables such as the injection speed, maximum injection pressure, and packing pressure can be evaluated as the change of the mold vibration during injection molding.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.78-84
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• 2012

Mold may experience deterioration of molding quality as the abrasion of mold occurring due to friction between mold and molded product works as allowance in the course of press process. Therefore, to improve the wear-resistance of mold, methods like nitriding, carburizing, flame and induction surface hardening treatment etc have been applied. However, as such methods are accompanied by problems like shape limitation or product deformation etc, laser surface treatment technology is under review as surface treatment method that can solve such problems. Therefore, in this study, mold material cast iron was surface-treated by using high power diode laser. In previous report 1 and report 2, the heat treatment characteristics were compared by the differences of die materials and shapes, then this paper observed microstructure by using optical microscope and scanning electronic microscope to analyze the structural difference of hardened zone, interface area and base metal after heat treatment. And the structural condition was grasped through EDS. As a result of microstructure, hardened zone showed formation of acicular martensite.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.52-60
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• 2005

Purpose. The intent of this study was to evaluate the effects of curing conditions on self-curing denture base resins to find out proper condition in self-curing resin polymerization. Materials and methods, In this study, 3 commercial self-curing denture base resins are used Vertex SC, Tokuso Rebase and Jet Denture Repair Acrylic. After mixing the self curing resin, it was placed in a stainless steel mold(3$\times$6$\times$60mm). The mold containing the resin was placed under the following conditions: in air at 23$^{\circ}C$; or in water at 23$^{\circ}C$; or in water at 23$^{\circ}C$ under pressure(20psi); or in water at 37$^{\circ}C$ under pressure(20psi) or in water at 50$^{\circ}C$ under pressure(20psi) , or in water at 65$^{\circ}C$ under pressure(20psi), respectively. Also heat-curing denture base resin is polymerized according to manufactures' instructions as control. Fracture toughness was measured by a single edge notched beam(SENB) method. Notch about 3mm deep was carved at the center of the long axis of the specimen using a dental diamond disk driven by a dental micro engine. The flexural test was carried out at a crosshead speed 0.5mm/min and fracture surface were observed under measuring microscope. Results and conclusion . The results obtained were summarized as follows : 1. The fracture toughness value of self-curing denture base resins were relatively lower than that of heat-curing denture base resin. 2. In Vertex SC and Jet Denture Repair Acrylic, higher fracture toughness value was observed in the curing environment with pressure but in Tokuso Rebase, low fracture toughness value was observed but there was no statistical difference. 3. Higher fracture toughness value was observed in the curing environment with water than air but there was no statistical difference. 4. Raising the temperature in water showed the increase of fracture toughness.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.3
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• pp.45-50
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• 2005

This paper proposed an efficient manufacturing system using the OMM (on-machine measurement) system. The OMM system is software-based 3D modeler for inspection on machine, and it is interfaced with machine tools via RS232C. The software is composed of two inspection modules; one is touch probe operating module, and the other is laser displacement sensor operating module. The module for touch probe needs the inspection feature extracted from CAD data. The touch probe moves to workpiece by three operating modes as follows: manual, general and automatic mode. The operating module of the laser displacement sensor is used to inspect profiles and very small holes. An advantage of this inspection method is the ability to execute on-line inspection during machining or afterward. The efficiency of proposed system which can predict and define the machining errors of each process was verified, so the developed system was applied to inspect a mold-base (cavity, core).

• Design & Manufacturing
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• v.17 no.2
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• pp.9-14
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• 2023

In this study, an experiment was conducted to confirm the applicability of the external shape control of the ultrasonic knife to the CFRTP material, which is the base material of thermoplastic. TC910 based on polyamide6 (PA6) was used as the material. The slope 와 and tool transfer speed of the material and tool were selected as process factors for processing, and the following results were obtained. Under all cutting conditions using an ultrasonic knife, friction heat caused by high-frequency vibration was issued at 150℃ at the contact part between the material and the knife during cutting. As a result of the cutting force analysis, the faster the transfer speed, the higher the cutting force as the angle of entry of the blade increased, and the size of the cutting force changed during cutting. As for the size of the burr in accordance with the transfer speed condition, the smallest burr occurred at 150mm/min in the side part, and the smallest burr occurred at 150mm/min and 200mm/min in the case of the outlet burr. The size of the burr according to the entry angle tended to decrease as the tool entry angle increased, and the side part tended to increase as the tool entry angle increased. As a result of the cutting surface analysis, it was confirmed that the base material was eluted under all conditions, and the faster the transfer speed, the lower the elution phenomenon of the base material. Based on the above results, cutting the CFRTP material with an ultrasonic knife is possible, but the effect on heat generation caused by friction needs to be minimized, and further research needs to be conducted on this.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.69-72
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• 2007

Cellulose is a beneficial material that has low cost, lightweight, high compatibility and biodegradability. Recently electroactive paper (EAPap) on cellulose base was discovered as a smart material and actuator through ion migration and piezoelectric effect. Furthermore cellulose has a potentiality to apply the display material, because of its high reflectivity, flexibility and high transmittance. The various shapes and height patterns of the Cellulose acetate (CA) solution, such as circle and honeycomb patterns, were fabricated and observed by field emission scanning electron microscope (FESEM, S4300 Hitachi). The resulting pattern showed uniform size in the large area without defect. After stretching the CA film with saponification process in the sodium methoxide in methanol solution, Most of the compositions become one directional ordered nanofibers below 50nm.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.38-44
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• 2002

In manufacturing die and mold, polishing: is important as it takes as much as 50% of the production cost. In this research, an attachable type polishing device to a WC machining center was developed. experiments were done with a special1y designed rotation type polishing device. Also an ultra-sonic (vibration type) waving device was introduced to acquire finer surface finishes. From the constructed data base based on the experimental results, it is shown that optimal polishing conditions are generated by the combined use of the rotation type tool and the vibration type tool.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.45-51
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• 2002

To reduce the cost and increase reliability of die and mold products, automation of the finishing (polishing) process is essential. A major element of automation is a reliable database and a knowledge base for polishing status. This paper presents a polishing expert system which can determine optimal polishing sequences and conditions by using an empirical formula and an experimental database. The simplex method was used for the curve fittings of the experimental results. Also a graphical user interface, which visualizes the optimized results, was developed.