• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.6
• /
• pp.160-165
• /
• 2002

A study on digital processes of injection mold in reverse engineering are presented. Reverse engineering is useful fur several cases, where user has no geometry information of object. Laser scanner is used to obtaining 3D coordinates of object. Sequences to process cloud data are described; sampling to reduce number of points, sorting to adjust the point order, and fitting to curve and surface, and so on. Split slide structure of mold is used fur undercut part and high viscosity material. Flow of injection molding are analysed to correct cooling channel and simulate molding conditions. NC tool paths are generated to carve core and cavity. The processes are performed in digital data for reduction of lead time and consecutive geometry data.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.852-855
• /
• 2003

Gas-Assisted Injection Molding(GAIM) process, that can be used to provide a hollow shape in a molding, is a variant of the conventional injection molding process. GAIM has many advantages such as reduction of material, sink mark. warpage. and lower injection pressure. Thus, GAIM has been widely applied in the industry to make moldings with a hollow channel such as handles, TV frames and so on. On the other hand, GAIM has some disadvantages such as slow cooling time and flow marks. In the disadvantages, hot gas core causes slow cooling of a molding and the overflow. which is to prevent flow mark. is waste of materials. To solve these problems, we developed a new GAIM system that we called RGIM(Reverse Gas Injection Molding). The RGIM has two special units; one is the overflow buffer, which is used for reduction of a material, and the other tile air unit, which is used for faster cooling of a molding. We conducted an experiment and simulation to verify the efficiency of the RGIM system. Through experiments and simulation, we confirmed the effectively operating of the RGIM system and extracted the optimum process conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.80-83
• /
• 2003

In this paper, the programming characteristics of the multi-bit devices based on SONOS structure are investigated. Our devices have been fabricated by $0.35\;{\mu}m$ complementary metal-oxide-semiconductor (CMOS) process with LOCOS isolation. In order to achieve the two-bits per cell operation, charges must be locally trapped in the nitride layer above the channel near the junction. Channel hot electron (CHE) injection for programming can operate in multi-bit using localized trap in nitride film. CHE injection in our devices is achieved with the single power supply of 5 V. To demonstrate CHE injection, substrate current (Isub) and one-shot programming curve were investigated. The multi-bit operation which stores two-bit per cell is investigated with a reverse read scheme. Also, hot hole injection for fast erasing is used. Due to the ultra-thin gate dielectrics, our results show many advantages which are simpler process, better scalability and lower programming voltage compared to any other two-bit storage flash memory. This fabricated structure and programming characteristics are shown to be the most promising for the multi-bit flash memory.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.546-550
• /
• 2002

This paper proposes an error compensation method that improves accuracy with geometry information of injection molding parts. Geometric information can give an improved accuracy in reverse engineering. Measuring data can not lead to get accurate geometric model, including errors of physical parts and measuring machines. Measuring data include errors which can be classified into two types. One is molding error in product, the other is measuring error. Measuring error includes optical error of laser scanner, deformation by probe forces of CMM and machine error. It is important to compensate these in reverse engineering. Least square method(LSM) provides the cloud data with a geometry compensation, improving accuracy of geometry. Also, the functional shape of a part and design concept can be reconstructed by error compensation using geometry information.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.1
• /
• pp.1-6
• /
• 2003

Engine emission regulations are becoming more stringent nowadays. In cold transient regime, about 80% THC is exhausted to the atmosphere in the first 200s (US FTP cycles). Accordingly, reducing emission levels in the cold period immediately after the engine start before the catalysts reach their working temperature will be an especially critical factor in meeting more stringent regulations in the future. In this study, the total hydrocarbon quantities are measured using a Fast FID with gasoline fuel for a 4-cylinde. Sl engine, including Secondary Air Injection (SAI) system. Commercial SAI device's direction is reverse to the exhaust flow. In this study, a swirl flow type SAI system which is positioned between the exhaust manifold and exhaust port, was developed. We compared the swirl type secondary air injection with a commercial secondary air injection of .everse flow. The swirl type SAI showed better results in reducing HC by 26% than the commercial flow type SAI of reverse flow which was caused by the better mixing between the exhaust gas and the secondary air.

• Transactions of Materials Processing
• /
• v.24 no.6
• /
• pp.437-442
• /
• 2015

The development of polishing technology has enabled the production of injection molds with high quality surfaces and shapes. For products such as mobile phones which require high quality performance the use of plastic materials has many constraints such as shrinkage and deflection. The purpose of the current research is to use reverse engineering in order to find and analyze the data of a selected aspherical lens and then creating a process to design an improved lens. Additionally, the improved lenses are subject to molding analysis. In order to solve this problem, the lens construction program, Zemax, was used to analyze and optimize performance. In the case of optimization, the object was to eliminate spherical aberration and to find good MTF data. The result of the optimization data was similar to the MTF data found from a random lens. Specific resin and analysis conditions were selected and CAD modeling was done to enhance the injection molding analysis.

• The Journal of Korean Academy of Prosthodontics
• /
• v.37 no.2
• /
• pp.167-184
• /
• 1999

The purpose of this study was to evaluate and compare the at of denture bases processed by injection pressing technic using laser scanner of reverse engineering technic. The auther duplicated 20 maxillary edentulous models and 20 mandibular edentulous models, which were scanned on HYSCAN 45C 3D BCANNER(Hymarc Co., Canada). The scanned data were stored in the personal computer using SURFACER (Imageware Co. U.S.A.) software program. After 40 dentures were cured by PERform Inkovac system, SR-Ivocap system, Palajet system, and Sulfon system, they were stored in water at room temperature fir 24 hours. The dentures were scanned on HYSCAN 45C 3D SCANNER(Hymarc Co., Canada). The scanned data were stored in the personal computer using SURFACER (Imageware Co., U.S.A.) software program. By overlapping two images using the same program, the fit between two surfaces was scaled by positive and negative errors. The obtained results were as follows 1. In the upper denture, most of the positive errors occurred on the lingual side of anterior alveolar ridge and the negative errors were on the flange of denture bases. 2. In the lower denture, most of the positive errors occurred on the inner side of lingual flange and the negative errors were on the border of anterior labial flange areas, 3. There were no statistical differences among the positive errors of the four types of injection denture curing methods and also no statistical differences between negative errors except only in negative maximum errors. 4. In PERform system and SR-Ivocap system, they have the tendency of inaccurate at of lower denture bases comparing to that of upper denture bases. 5. The negative error scales were greater than the positive error scales in all types of injection denture curing methods.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.10a
• /
• pp.275-276
• /
• 2006

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.211-212
• /
• 2006

Production components fabricated by metal powder injection molding are analyzed for features to identify the design window for this powder technology. This reverse approach lets the designer see where PIM has a high probability to succeed. The findings show that the most suitable components tend to be less than 25 mm in size and less than 10 g in mass, are slender, and have high complexity.

• International Journal of Precision Engineering and Manufacturing
• /
• v.6 no.2
• /
• pp.12-18
• /
• 2005

A geometric compensation of thin-walled molded parts in reverse engineering is presented. Researches in reverse engineering have focused on the fitting of points to curves and surfaces. However, the reconstructed model is not the geometric model because the molded parts have some dimensional errors in measurements and deformation during molding. Geometric information can give an improved accuracy in reverse engineering. Thus, measurement data must be compensated with geometric information to reconstruct the mathematical model. The functional and geometric concepts of the part can be derived from geometric information. LSM (Least square method) is adopted to determine the geometric information. Also, an example of geometric compensation is given to improve the accuracy of geometric model and to inspect the reconstructed model.