• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2005년도 추계 학술대회논문집
• /
• pp.245-248
• /
• 2005

SCRamjet is the key technology for hypersonic flight over mach number 6. It is characterized by very short residence time in combustor because its internal flow is supersonic. In this short time, the whole process of combustion must be done. Especially numerical study of combustor is important because air-fuel mixing rate influences the performance of combustor. Various methods of air-fuel mixing enhancement are proposed. Among these, cavity injection method is selected to study in this paper. The numerical study is conducted with the variation of the cavity length at the fixed height of unit and jet injection on the downstream of cavity.

• Fibers and Polymers
• /
• 제2권1호
• /
• pp.163-172
• /
• 2001

To determine three-dimensional fiber orientation states in injection-molded short fiber composites a CLSM (Confocal Laser Scanning Microscope) is used. Since the CLSM optically sections the composites, more than two cross-sections either on or below the surface of the composite can be obtained. Three dimensional fiber orientation states can be determined with geometric parameters of fibers on two parallel cross-sections. For experiment, carbon fiber reinforced polystyrene is examined by the CLSM. Geometric parameters of fibers are measured by image analysis. In order to compactly describe fiber orientation states, orientation tensors are used. Orientation tensors are determined at different positions of the prepared specimen. Three dimensional orientation states are obtained without the difficulty in determining the out-of-plane angles by utilizing images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell-core structure along the thickness of the specimen.

• 전력전자학회논문지
• /
• 제23권1호
• /
• pp.72-75
• /
• 2018

An initial rotor position estimation method is proposed in this study for an interior permanent-magnet synchronous motor without a resolver or an absolute encoder. This method uses least squares approximation to estimate the initial rotor position. The magnetic polarity is identified by injection of short pulses. The proposed estimation process is robust because it does not require complex signal processing that depends on the performance of a digital filter. In addition, it can be applied to various servo systems because it does not require additional hardware. Experimental results validate the effectiveness of the proposed method using a standard industrial servomotor with interior-permanent magnets.

• 한국자동차공학회논문집
• /
• 제9권3호
• /
• pp.9-17
• /
• 2001

This paper is the second of 3 companion papers which investigate axial stratification process. In-cylinder fuel behavior has been investigated in the port injected Sl engine by visualizing for the purpose of understanding stratification. Planar laser light sheet from an Nd:YAG laser has been illuminated through the transparent quartz cylinder of the single cylinder optical engine and the Mie scattered light has been captured through the quartz window in the piston head with an ICCD camera. Fuel has been replaced with an air-ethanol mixture to utilize atomized fuel spray fur the visualization purposes. This results have been compared with steady flow concentration measurement. For low/medium swirl port, the early injection makes such a fuel distribution state that is upper-rich, middle-lean and lower-rich along the combustion chamber and cylinder by tumbling motion. On the other hand, the late injection induces upper-rich, middle-lean and lower-rich state due to the short fuel penetration.

• Journal of Mechanical Science and Technology
• /
• 제15권12호
• /
• pp.1616-1622
• /
• 2001

Fiber composite materials are widely used in aerospace industries due to their high specific strength and stiffness. Especially, the increasing use of polymer composite materials for injection of automobile components has led to a considerable interest in the application of stress pattern analysis by thermal emission to these composite materials. Therefore, in this study the microstructure of glass fiber orientation at the parent and weld line of polycarbonate is observed by a light transmission. And we also investigate a stress concentration model of a notch including short glass fibers. Especially the polymer injection weld reorients the fiber to suggest a new method for the evaluation of inhomogeneous deformation.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1999년도 춘계학술대회논문집
• /
• pp.136-142
• /
• 1999

The injection molded part shrinks in the process of solidification by the amount of the coefficient of linear thermal expansion multiplied by the temperature difference between the coefficient of linear thermal expansion multiplied by the temperature difference between the room temperature and the temperature at which the solid structure is formed in the mold And it is called warpage for this type of deformation that shrinkage are not uniform throughout the injection molded part. To predict warpage phenomena in the articles the results obtained theoretically from the change of mold temperature fiber content of composites have been compared with exsperimental results.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1999년도 춘계학술대회논문집
• /
• pp.218-224
• /
• 1999

It is necessary to improve mechanical and optical properties in the optical disk substrates as the information storage devices with high storage density using short wavelength laser are being developed. Injection compression molding is regarded as the most suitable process to manufacture optical disk substrates with high is regarded as the most suitable process to manufacture optical disk substrates with high dimensional accuracy low residual stresses and superb optical properties In the present study polycarbonate optical disk substrates were fabricated by injection compression molding and the birefringence regarded as one of the most important optical properties for optical disk is measured. The effects of various processing conditions upon the development of birefringence distribution were examined experimentally. It was found that the value of the birefringence distribution were very sensitive to the mold wall temperature history and the variance of the birefringence distribution in the radial direction was affected by the level of the packing and the compression pressure.

• International Journal of Automotive Technology
• /
• 제6권5호
• /
• pp.507-511
• /
• 2005

Recently, many solution have been suggested to development of plastic products. Among many manufacturing technologies for plastic parts, the injection molding process is very attractive because of its low production cost and short cycle time. In this paper, the plastic ball seat of a ball joint, one of the essential components for automotive suspension or steering system, was studied to enhance its mechanical performance and durability by using PA66 that is reinforced polymeric plastic resin. But ball seat has some trouble in manufacture process. And strength of molded part is not enough to use. For the quality stabilization and reliability of injection molded parts, we designed the mold cavities through analytical simulation software and tested the mechanical performance for the injection molded ball-seat parts. After modification, tensile strength increases by about $13.5\%$. Strength and quality stabilization is improved.

• 한국기계가공학회지
• /
• 제20권12호
• /
• pp.129-135
• /
• 2021

Injection molding is a manufacturing method of melting the polymer resin and injecting it into a mold to molding it into the desired form. Due to the short molding time and outstanding formability, complex products can be shaped with high precision and it is the most widely used polymer molding method. However, there may be areas that are not filled depending on the location of the injection gate where polymer resin is injected. Formability is determined by deformation and surface precision due to the impact of residual stress after molding. Hence, choosing the location of the injection gate is very important and molding analysis of injection molding is essential to reduce the cost of the mold. This study evaluated the injection formability based on the location of the injection gate of the vertical machining center ATC tool port using injection molding analysis and the results were compared and analyzed. Injection molding analysis was conducted on filling, packing, and deformation according to the location of the gate of the ATC tool port. From each injection gate location, filling time, pressure, and maximum deformation were compared. At gate 2, conditions of molding time and the location of the gate were far superior in production and quality. Gate 2 produced the smallest deformation of 0.779mm with the best quality.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 춘계학술대회 논문집
• /
• pp.641-642
• /
• 2012