• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.706-709
• /
• 2005

Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed in multi-cavity injection mold. These filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during the injection molding processing. This paper presents a solution of these filling imbalances by using runner core pin which creates a symmetrical shear distribution within runner and the effects on filling imbalance when modifying a shape of runner core pin. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed. In addition we investigated how filling imbalances were affected by shape of runner core pin.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.39-42
• /
• 2005

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filling imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.

• Design & Manufacturing
• /
• v.12 no.3
• /
• pp.55-59
• /
• 2018

In a multi-cavity mold having a runner layout of a fish bone structure, problems of unbalanced filling between cavities occur constantly. Unbalanced charging lowers the dimensional accuracy of a molded article and causes deformation after molding. To solve this problem, the gate size connected to each cavity is adjusted using the BGV (Balanced Gate Value) equation. In this paper, in order to solve the filling imbalance problem of the runner layout mold of fish bone structure through injection molding analysis study, we compared the charging imbalance phenomenon before and after improvement after adjusting the gate size by applying BGV equation. From the results of the molding analysis, the shrinkage ratio before and after the improvement of the molded article was improved by only about 0.08%. Based on these results, it was confirmed that the charging imbalance problem was not significantly improved even when the BGV equation was applied.

• Journal of the Korean Institute of Rural Architecture
• /
• v.21 no.3
• /
• pp.25-32
• /
• 2019

This study is to derive the types of displacement and damage that occur in wooden architecture cultural assets. Although the wooden architectural cultural assets are being repaired through continuous maintenance, secondary problems frequently occur. This is because the root cause of the problem has yet to be solved. The types of displacement and damage that occur in the wooden architecture cultural asset are classified into three parts: the foundation section, the gagu section, and the roof section. In turn, the three main factors that lead to displacement and damages are the structures' load impact, the durability deterioration, and the imbalance. Load impact is a phenomenon in which the member is subjected to a load that causes deformation or cracks. Durability decline is a natural phenomenon that reduces the performance of lumber as a result of check shake, termite damage, and decay. The imbalance is a condition in which the lumber is twisted and the force balance is lost, due to either drying shrinkage or displacement of the gagu section.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.09a
• /
• pp.13-16
• /
• 2005

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filing imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.4
• /
• pp.1581-1588
• /
• 2011

In this study, flow characteristics in a multi-cavity injection molding process were investigated. One of main problems occurred in the multi-cavity molding is a flow imbalance among cavities since it affects physical properties and quality of products. Charge imbalance is caused by the uneven shear stress. Therefore, changes in viscosity affect the physical properties of resin and injection conditions differ in the filling imbalance phenomenon. Through, this study focus on experimental studies of flow imbalance for PC and PP resin occurring in a balanced delivery system. Experimental results were compared with CAE results. By experimental and CAE analysis, main cause for the flow imbalance is temperature distribution in cross section of runner. New runner system with a simple change of runner shape was suggested to avoid the flow imbalance. A series of simulation to confirm feasibility of Volume Runner's effects was conducted using injection molding CAE.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.2
• /
• pp.18-26
• /
• 2015

In this paper, we studied the method for analyzing and estimating the parameters that induce I/Q imbalance in the repeater using direct conversion RF. In repeater, amplitude, phase, and filter mismatch are generated in the receiving-end which converts RF signal to baseband signal. And amplitude and phase mismatch are generated in the transmitting-end which converts baseband signal to RF signal. Accordingly, we modeled the parameters that cause I/Q imbalance in the structure of the repeater in order, and proposed a feedback test structure from the transmitting-end to the receiving-end for estimating the corresponding parameters. By comparing the test transmitting signal and received signal, it is possible to estimate the I/Q imbalance parameters which occurred from mixed components of real and imaginary part. And it was confirmed that I/Q imbalance phenomenon has been properly compensated with estimated parameters at the direct conversion RF repeater.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.11
• /
• pp.3-10
• /
• 2014

Direct conversion receiver(DCR) gets noticed for integration and cost reduction of wireless communication systems instead of the heterodyne receiver which uses complex filter. But DCR has several factors in performance degradation. One of them is I/Q imbalance phenomenon, that is amplitude and phase mismatch between real and imaginary part of receiver. Accordingly, researches are being carried to improve the I/Q imbalance problem. However, the tendency of the broaden bandwidth of communication systems, low pass filter(LPF) mismatch problem affects severely in I/Q mismatch phenomenon at the DCR. To study this problem, we generated 10MHz broadband signal and shifted it ${\pm}8MHz$ from the center frequency. The signal is affected by LPF mismatch and it appears as frequency selective distortion. Thus, LPF mismatch model is added to I/Q imbalance model which conventionally dealt with amplitude and phase mismatches. In addition, we proposed the compensation method for each factors of mismatch. As the simulation results, the proposed I/Q mismatch compensator resolves the frequency selective distortion which occurred by the existing LPF mismatch.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.1
• /
• pp.137-142
• /
• 2005

Gas-Assisted Injection Molding(GAIM) is an innovative technology for producing plastic parts and has been received extensive attention in the plastic manufacturing industries. But, due to gas-polymer interacting during the gas injection phase, the process has significantly different characteristics from conventional injection molding and, therefore, the control of the process requires much technical knowledge in processing and materials. The experiment was performed about variations of gas-penetration length that is affected by filling imbalance resulting from the structure of runner. The Taguchi method was used for the design of experiment. The most effective factors for the gas-penetration length were the shot size and mold temperature. The most effective factors for the difference of the gas-penetration length were the melt temperature and shot size. This study also discussed the filling imbalance phenomenon in a unary branch runner type mold that has geometrically balanced runner.

• Transactions of Materials Processing
• /
• v.15 no.1 s.82
• /
• pp.42-46
• /
• 2006

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filling imbalances are one of the most significant factors to affect quality of plastic parts. Filling imbalances are results from non-symmetrical shear rate distribution within melt when it flows through tile runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution for these filling imbalances by using Runner Core pin (RC pin). The Runner Core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using Runner Core pin, a remarkable improvement in reducing filling imbalances was confirmed.