• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.324-328
• /
• 2002

Semi-Solid Diecasters usually carry out the Semi-Solid diecasting experiments before producing new casts. At the Semi-Solid diecasting stages, the runner-gate part has been always repeatedly corrected, which leads to a tedious processing time and increased processing cost. A large amount of experience is essential in manual assessment and if the design is defective, much time and a great deal of efforts will be wasted in the modification of the die. In this study, design system has been developed based on design database. In addition, gate experiment for gating system design has been carried out to append the database. It is possible for engineers to make efficient gating system design of Semi-Solid diecasting and it will result in the reduction of expenses and time to be required. The detailed contents of the research are described in the followings. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FVM softwares, MAGMAsoft, to form a useful package.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.8
• /
• pp.116-125
• /
• 2002

Semi-Solid Diecasters usually carry out the Semi-Solid diecasting experiments before producing new casts. At the Semi-Solid diecasting stages, the runner-gate part has been always repeatedly corrected, which leads to a tedious processing time and increased processing cost. A large amount of experience is essential in manual assessment and if the design is defective, much time and a great deal of efforts will be wasted in the modification of the die. In this study, design system has been developed based on design database. In addition, gate experiment for gating system design has been carried out to append the database. It is possible for engineers to make efficient gating system design of Semi-Solid diecasting and it will result in the reduction of expenses and time to be required. The detailed contents of the research are described in the followings.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.288-291
• /
• 2003

For the purpose of building the more efficient knowledge learning system, it is very important to make a good structure of the knowledge system first of all. The well designed knowledge system can make the stored knowledge to be easily accessed for knowledge acquisition and extraction. Expert knowledge can also play a good role for controlling. Accordingly, in this paper we propose the Hierarchical modular system with expert knowledge gating mechanism. This system consists of the mechanisms for knowledge acquisition, constructing the associative memory, knowledge inference and extraction according to the expert knowledge gating mechanism. We applied this system to the medical diagnostic area for classifying Virus(coxackie virus, echovirus, cold), Rhinitis(Nonallergic, allergic) and tested with symptom data

• 대한방사선치료학회:학술대회논문집
• /
• 2005.06a
• /
• pp.13-17
• /
• 2005

Introduction : For stereotactic radiosurgery (SRS) of a tumor in the region whose movement due to respiration is significant, like Lung lower lobe, the gated therapy, which delivers radiation dose to the selected respiratory phases when tumor motion is small, was peformed using the Respiratory gating system and its clinical effectiveness was evaluated. Methode and Materials : For two SRS patients with a tumor in Lung lower lobe, a marker block (infrared reflector) was attached on the abdomen. While patient' respiratory cycle was monitored with Real-time Position Management (RPM, Varian, USA), 4D CT was performed (10 phases per a cycle). Phases in which tumor motion did not change rapidly were decided as treatment phases. The treatment volume was contoured on the CT images for selected treatment phases using maximum intensity projection (MIP) method. In order to verify setup reproducibility and positional variation, 4D CT was repeated. Result : Gross tumor volume (GTV) showed maximum movement in superior-inferior direction. For patient $\#$1, motion of GTV was reduced to 2.6 mm in treatment phases ($30\%\~60\%$), while that was 9.4 mm in full phases ($0\%\~90\%$) and for patient $\#$2, it was reduced to 2.3 mm in treatment phases ($30\%\~70\%$), while it was 11.7 mm in full phases ($0\%\~90\%$). When comparing two sets of CT images, setup errors in all the directions were within 3 mm. Conclusion : Since tumor motion was reduced less than 5 mm, the Respiratory gating system for SRS of Lung lower lobe is useful.

• Journal of Korea Foundry Society
• /
• v.20 no.2
• /
• pp.97-103
• /
• 2000

In this study, a design of experiment, Taguchi method, was applied to optimize gating system design of escalator step die casting parts. Six shape factors which affect filling sequence of melt are adopted and divided into two levels respectively. Initial feeding differences of melt which were calculated by using S/N(signal-to-noise) ratio in each condition were demonstrated with the simulation of Flow-3D software program. Variations of S/N ratio according to shape factors were obtained and the optimal condition of gating system could also be obtained. It could be found that width of gate, contact angle of gate, thickness of runner are more effective factors on the filling sequence of melt than the others in this case of escalator step die casting parts. It showed that the economical gating system and sound filling sequence of melt were obtained by using Taguchi method.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.5
• /
• pp.597-608
• /
• 2021

The control head components used in small military vessels are designed to be domestically produced, prototypes, structural analysis, and casting methods are designed and cast. The control head assembly consists of a lever, an aluminum outside cover, Middle, front gear cover, back gear cover, and a zinc worm gear. In order to reverse the design of each component, 3D scanning device was used, 3D modeling was performed by CATIA, and prototype productions were carried out by 3D printer. In order to reduce the cost of components, gating system is used by gravity casting method. The SRG ratio of 1:0.9:0.6 was set by applying non-pressurized gating system to aluminum parts, 1:2.2:2.0 and pressurized gating system to zinc parts, and the shapes of sprue, runner and gate were designed. The results of porosity were also confirmed by casting analysis in order to determine whether the appropriate gating system can be designed. The results showed that all parts started solidification after filling completely. ANSYS was used for structural analysis, and the results confirmed that all five components had a safety factor of 15 more. All castings are free of defects in appearance, and CT results show only very small porosity. ZnDC1 zinc alloy worm gear has a tensile strength of 285 MPa and an elongation of 8%. The tensile strength of the four components of A356 aluminum alloy is about 137-162 MPa and the elongation is 4.8-6.5%.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.5
• /
• pp.589-596
• /
• 2021

In this study, the optimum gating system was designed, and the two zinc alloy worm gears were manufactured in single process by applying a symmetrical gating system with 2 runners. The SRG ratio is set to 1 : 0.9 : 0.6, and the cross-sectional shapes such as sprue, runner and gate are designed. In order to determine whether the design of the gating system is appropriate, casting analysis was carried out. It takes 4.380 s to charge the casting 100%, 0.55 to 0.6 m/s at the gates and solidification begins after the casting is fully charged. The amount of air entrapment is 2% in the left gear and 6% in the right gear. Hot spots occurred in the center hole of the gear, and pores were found to occur around the upper part of the hole. Therefore, the design of the casting method is suitable for worm gears. CT analysis showed that all parts of worm gear were distributed with fine pores and some coarse pores were distributed around the central hole of worm gear. The yield strength and tensile strength were 220 MPa, 285 MPa, and the elongation rate was 8%. Vickers hardness is 82 HV.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.6
• /
• pp.2479-2484
• /
• 2018

The filter bank multicarrier modulation (FBMC) technique is one of multicarrier modulation technique (MCM), which is mainly used to improve channel capacity of cognitive radio (CR) network and frequency spectrum access technique. The existing FBMC System contains serial to parallel converter, normal QAM modulation, Radix2 inverse FFT, parallel to serial converter and poly phase filter. It needs high area, delay and power consumption. To further reduce the area, delay and power of FBMC structure, a new clock gating technique is applied in the QAM modulation, radix2 multipath delay commutator (R2MDC) based inverse FFT and unified addition and subtraction (UAS) based FIR filter with parallel asynchronous self time adder (PASTA). The clock gating technique is mainly used to reduce the unwanted clock switching activity. The clock gating is nothing but clock signal of flip-flops is controlled by gate (i.e.) AND gate. Hence speed is high and power consumption is low. The comparison between existing QAM and proposed QAM with clock gating technique is carried out to analyze the results. Conversely, the proposed inverse R2MDC FFT with clock gating technique is compared with the existing radix2 inverse FFT. Also the comparison between existing poly phase filter and proposed UAS based FIR filter with PASTA adder is carried out to analyze the performance, area and power consumption individually. The proposed FBMC with clock gating technique offers low power and high speed than the existing FBMC structures.

• Journal of Korea Foundry Society
• /
• v.37 no.6
• /
• pp.173-180
• /
• 2017

In this paper, the casting design of the integrated twin-scroll turbine housing with exhaust manifold using stainless steel is investigated. Due to the complexity in its geometry and the poor castability of stainless steel, it is more crucial to set up the appropriate casting design to avoid casting defects. Gas porosity and shrinkage formation with the changes of gating systems (one-/two-side), riser conditions and pouring temperatures are examined via casting simulation and virtual castings. Simulation results show that two-side gating system produced better quality casting than that of one-side gating system, minimizing the gas content of the castings and it is also verified by X-ray analysis for the virtual castings. For the changes of riser conditions and pouring temperatures in the two-side gating system, it is found that the change of the height of two risers plays an important role in obtaining the best quality by reducing shrinkage defects.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.405-408
• /
• 2007

Vestibular hair cells, the sensory receptors of vestibular organs, selectively amplify miniscule stimuli to attain high sensitivity. Such selective amplification results in compressive nonlinear sensitivity, which plays an important role in expanding dynamic range while ensuring robustness of the system. In this study, negative stiffness mechanism, a mechanism responsible for the selective amplification by vestibular hair cells, is applied to a simple mechanical system consisting of an array of inverted pendulums. The structure and working principle of the system have been inspired by gating spring hypothesis proposing that opening and closing of transduction channels contributes to the global stiffness of vestibular hair bundle. Parameter study was carried out to analyze the effect of each parameter on the compressive nonlinearity of suggested model.