• Journal of Power Electronics
• /
• v.11 no.4
• /
• pp.520-526
• /
• 2011

This paper presents a balanced soft-chopping circuit and a modified PI controller for a high speed 4/2 Switched Reluctance Motor (SRM) with a 16 pulse per revolution encoder. The proposed balanced soft-chopping circuit can supply double the switching frequency in the fixed switching frequency of power devices to reduce current ripple. The modified PI controller uses maximum voltage, back-emf voltage and PI control modes to overcome the over-shoot current due to the time delay effect of current sensing. The maximum voltage mode can supply a fast excitation current with consideration of the hardware time delay. Then the back-emf voltage mode can suppress the current over-shoot with consideration of the feedback signal delay. Finally, the PI control mode can adjust the phase current to a desired value with a fast switching frequency due to the proposed balanced soft-chopping technology.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.6
• /
• pp.931-937
• /
• 2004

Simultaneous filling is a goal in plastic injection mold that has multi cavities. The moldings which have not been filled at the same time have undesired faults such as dimension inaccuracy, residual stress, law mechanical strength, etc. The best way to simultaneous fill is to be injected in a geometrically balanced runner system. In a general processing, however, in balanced runner system mold, filling imbalance would be observed in cavities. These phenomena result from molten polymer's characteristics and circumstances in balanced runner. In this study, the degree of filling imbalance (DFI) was defined for showing rate of filling imbalance in geometrically balanced injection mold that has 8 cavities. Before the main experiment, an injection molding simulation was conducted to know a pattern of filling imbalance with Moldflow software. There were somewhat differences between results of experiment and simulation about the filling imbalance. The reason for the difference was that the software have not concerned about a situation in a real flow channel. It was also investigated how the injection speed affected on filling imbalance in the experiment.

• Journal of the Korean Regional Science Association
• /
• v.35 no.4
• /
• pp.19-32
• /
• 2019

Since the 2000s, China has been trying to develop the mid- and western regions and reduce regional disparity between the eastern region and the others by construction of the eight HSR corridors known as 4+4. The high-speed railway is known to have a positive impact on regional economic development by improving accessibility between regions. However, some studies point out that the high-speed railways could worsen regional imbalances. The purpose of this study is to examine the impact of the high-speed railway on regional economic growth and balanced development in China, using the beta-convergence model. In particular, we focused on how the effects of high-speed trains on regional economic development varied depending on the level of development. The analysis was conducted centering on the Shanghai-Chengdu line which is connecting eastern, central and western regions with different levels of development.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.6
• /
• pp.3731-3735
• /
• 2015

This study reports the relationship between rollingstock weight and acceleration performance for HEMU-430X, the first electric multiple unit developed in Korea. While maintaining the consumed power, the total train weight was deliberately varied by 2%, by adding and removing weights, and the it was shown that the lighter train was found to have higher acceleration performance and hence better suited for maximum speed tests below the speed of 413km/h. According to the power consumption analysis based on the velocity data collected per 0.1 second, the balanced speed, when the traction force and air resistance become equal, was determined to be 419km/h for HEMU-430X, which is in agreement with tested result. It is expected that the analyses in this study will be utilized for the speed tests in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.1
• /
• pp.1-10
• /
• 1999

In this paper, a method of canceling and suppressing differential-mode crosstalk-noise signals caused by non-uniform coupling between two transmission lines in UTP(Unshielded Twisted Paris) modular jacks is discussed. Differential-mode crosstalk-noise signals in balanced transmission lines in UTP modular jacks were suppressed by inserting auxiliary capacitance between balanced transmission line pairs which are located closely enough to be effectively coupled each other. To verify the effectiveness of the inserted capacitances, precisely calculated auxiliary capacitances were applied to 10 pin modular jacks which are used in local area networks at 100 Mb/s with unshielded twisted pair-cables. The NEXT(Near-End Crosstalk) losses were measured to prove its applicability.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.10a
• /
• pp.54-57
• /
• 2004

Almost all injection molds have multi-cavity runner for mass production, which are designed with geometrically balanced runner system in order to minimize filling imbalance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have sometimes been observed. These filling imbalances have historically been considered as result of uneven mold temperature and mold deflection, but it actually results from non-symmetrically shear, pressure, temperature distribution within melt material as it flows through the runner system. Filling imbalance could be decreased by modifying processing conditions that are related to shear, pressure, temperature such as injection rate, mold temperature, injection pressure, melt temperature. In this study, a series of experiment was conducted using Taguchi method to determine which processing condition influence as the primary cause of filling imbalance in geometrically balanced runner system. As a result of experiments, this paper could present an optimal processing condition to minimize variable that brings about filling imbalance geometrically balanced runner system

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.4 no.3
• /
• pp.322-334
• /
• 2012

This paper shows the numerical and experimental results about the hydrodynamic characteristics of X-Twisted rudders having continuous twist of the leading edge along the span. All the results were compared with those of the semi-balanced rudder. Calculation through the Reynolds-Averaged Navier-Stokes Equation (RANSE) code with propeller sliding meshes shows large inflow angle and fast inflow velocity in the vicinity of ${\pm}0.7$ R from the shaft center, so it may cause cavitation. Also, X-Twisted rudder has relatively small inflow angles along the rudder span compared with semi-balanced rudder. For the performance validation, rudders for two large container carriers were designed and tested. Cavitation tests at the medium sized cavitation tunnel with respect to the rudder types and twisted angles showed the effectiveness of twist on cavitation and the tendency according to the twist. And the resistance, self-propulsion and manoeuvring tests were also carried out at the towing tank. As a result, in the case of X-Twisted rudder, ship speed was improved with good manoeuvring performance. Especially, it was found out that manoeuvring performance between port and starboard was well balanced compared with semi-balanced rudders.

• Proceedings of the KSR Conference
• /
• 2001.05a
• /
• pp.289-294
• /
• 2001

A curved track needs balanced super elevation according to the speed of the passing train and it is limited by maximum allowable amount. Therefore, passing speed at high degree curved track has to be controlled below the limits. Accurate position of the Speed Limit Post(SLP), which shows allowable speed of curved track dose not regulated so design and line side maintenance engineer adopt the position differently, When the rate of cant deficiency is considered on transition-curved section, the SLP should be located at the beginning point of the transition curve so as to control the speed of passing train and it will increase ride quality to passenger.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.8
• /
• pp.15-21
• /
• 1996

This paper describes data placement schemes that provide uniform and balanced to multiple disks load for retrievals of VBR (variable bit rate) video at varying retrieval speeds. To support maximum concurent users at arbitrary-speed playbacks in a disk-arry based system, the hot spot disks should be carefully avoided. In this paper, we extend the proposed scheme, prime round-robin(PRR), for VBR video. In addition, we have compared the performance of PRR and PRR (PRR extension).

• Journal of Electrical Engineering and Technology
• /
• v.7 no.2
• /
• pp.200-206
• /
• 2012

In order to develop a deep-underground great train express (GTX) in South Korea, the specifications decision and development of a traction control system (including an inverter and a traction motor), which considers a variety of route conditions, must be advanced. In this study, we examined the running resistance properties of a high-speed traction system based on a variety of tunnel types and vehicle organization methods. Then, we studied the power requirements necessary for the traction motor to maintain balanced speed in the high-speed traction system. From this, we determined the design criteria for the development of a high-speed traction system for use in the deep-underground GTX. Finally, we designed a linear induction motor (LIM) for a propulsion system, and we used the finite element method (FEM) to analyze its performance as it travelled through deep-underground tunnels.