• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1212-1220
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• 2013

In general, for a large power system like DC distribution system for buildings, several power converters are modularized for parallel operation. However, in parallel operation, inconsistency of parameters in each module causes circulating current in the whole system. Circulating current is directly related to loss, and, therefore, it is most important for the safety of the power system to supply the suitable current to each module. This paper proposes a control method to reduce circulating current caused during parallel operation. Accordingly, the validity of parallel operation system including response characteristics and normal state was verified by simulation and experiment result.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.734-739
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• 2001

In this paper, we develop a six-axes machining center tool(MCT) and CAD/CAM system. The MCT consists of two mechanical parts, i.e., a X-Y-Z Cartesian coordinate typed MCT and a parallel-typed tilting table. Kinematics and singularity are accomplished to design the parallel-typed tilting table, and CAD/CAM system is developed for the six-axes MCT, which requires the commands of position as well as orientation for machining of complex shape. The CAD/CAM system has a tool path generator, a NC code generator and a graphic simulator. This paper designs the parallel-typed tilting table to meet the desired specification and presents the results of tool path, NC code and graphic simulation.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.90-94
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• 1998

The parallel inverter is popularly used because of its fault-tolerance capability, high-current outputs at constant voltages and system modularity. The conventional parallel inverter usually employes active and reactive power control or frequency and voltage droop control. However, these approaches have the disadvantages that the response time of parallel inverter control is slow against load and system parameter variation to calculate active, reactive power, frequency and voltage. This paper describes a novel control scheme for power equalization in parallel connected inverter. The proposed scheme has a fast power balance control response, a simplicity of implementation, and inherent peak current limiting capability since it employes a instantaneous current/voltage control with output voltage and current balance and output voltage regulation. A design procedure for the proposed parallel inverter controller is presented. Futhermore, the proposed control scheme is verified through the simulation in various cases such as the system parameter variation, the control parameter variation and the nonlinear load condition.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.59-67
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• 2003

This paper presents a new approach for the use of smart materials, piezoelectric materials of PVDF and PZT, for vibration attenuation of a planar parallel manipulator. Since lightweight linkages of parallel manipulators deform under high acceleration/deceleration, an active damper is needed to attenuate vibration due to structural flexibility of linkages. Based on the dynamic model of a planar parallel manipulator, an active damping controller is developed, which consists of a PD feedback control scheme, applied to linear electrical motors, and a linear velocity feedback (L-type) scheme applied to either PVDF layer or PZT actuator(5). Simulation results show that piezoelectric materials yield good damping performance, resulting in precise manipulations of a planar parallel manipulator.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.188-193
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• 2015

This paper presents a new byte-wise BCH (4122, 4096, 2) decoder, which treats byte-wise parallel operations so as to enhance its throughput. In particular, we evaluate the parallel processing technique for the most time-consuming components such as syndrome generator and Chien search owing to the iterative operations. Even though a syndrome generator is based on the conventional LFSR architecture, it allows eight consecutive bit inputs in parallel and it treats them in a cycle. Thus, it can reduce the number of cycles that are needed. In addition, a Chien search eliminates the redundant operations to reduce the hardware complexity. The proposed BCH decoder is implemented with VHDL and it is verified using a Xilinx FPGA. From the simulation results, the proposed BCH decoder can enhance the throughput as 43% and it can reduce the hardware complexity as 67% compared to its counterpart employing parallel processing architecture.

• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.298-306
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• 2013

The scale invariant feature transform (SIFT) is an effective algorithm used in object recognition, panorama stitching, and image matching. However, due to its complexity, real-time processing is difficult to achieve with current software approaches. The increasing availability of parallel computers makes parallelizing these tasks an attractive approach. This paper proposes a novel parallel approach for SIFT algorithm implementation using a block filtering technique in a Gaussian convolution process on the SIMD Pixel Processor. This implementation fully exposes the available parallelism of the SIFT algorithm process and exploits the processing and input/output capabilities of the processor, which results in a system that can perform real-time image and video compression. We apply this implementation to images and measure the effectiveness of such an approach. Experimental simulation results indicate that the proposed method is capable of real-time applications, and the result of our parallel approach is outstanding in terms of the processing performance.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.952-958
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• 2009

This article presents a combined structure of serial and parallel mechanisms for a humanoid robot. The 3 DOF parallel structure is designed and added to the waist of the humanoid robot arm to give flexible bending and rotating motions. Forward and inverse kinematics of a serial and parallel robot have been analyzed to generate motions. Simulation studies of verifying kinematics solutions of the parallel robot have been done. Experimental studies of mimicking shake-hands motion have been conducted to show the feasibility and usability of the combined structure.

• Journal of Power Electronics
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• v.15 no.4
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• pp.886-898
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• 2015

The design feasibility of a micro unidirectional DC transmission system based on an input-parallel output-parallel (IPOP) converter is analyzed in this paper. The system consists of two subsystems: an input-parallel output-series (IPOS) subsystem to step up the DC link voltage, and an input-series output-parallel (ISOP) subsystem to step down the output voltage. The two systems are connected through a transmission line. The challenge of the delay caused by the communication in the control system is addressed by introducing a ring communication structure, and its influence on the control system is analyzed to ensure the feasibility and required performance of the converter system under practical circumstances. Simulation and experiment results are presented to verify the effectiveness of the proposed design.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.52-60
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• 2019

In this study, the performance and structure of a parallel ejector comprised of multiple single ejectors were confirmed through numerical analysis. The same design variables (mass suction ratio, compression ratio, and expansion ratio) relevant to the performance of a single ejector were considered in the design of the parallel ejector. Analytical results showed that there was no significant difference in the performance of either system related to the operating mass suction ratio; however, the systemsize was significantly reduced. In addition, it was confirmed that when ejectors of the same performance capacity are arranged in parallel, the combined mass suction ratio is lower than that of the single ejector, allowing a lower pressure to be realized. The results of the analysis indicated that the parallel ejector's performance is not significantly different from that of any single ejector, but confirmed that the parallel ejector can offer a configurationdependent advantage in size and operation.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.480-483
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• 1997

A fossil power plant can be modeled by a lot of algebraic equations and differential equations. When we simulate a large, complicated fossil power plant by a computer such as workstation or PC, it takes much time until overall equations are completely calculated. Therefore, new processing systems which have high computing speed is ultimately needed to develope real-time simulators. Vital points of real-time simulators are accuracy, computing speed, and deadline observing. In this paper, we present a enhanced strategy in which we can provide powerful computing power by parallel processing of DSP processors with communication links. We designed general purpose DSP modules, and a VME interface module. Because the DSP module is designed for general purpose, we can easily expand the parallel system by just connecting new DSP modules to the system. Additionally we propose methods about downloading programs, initial data to each DSP module via VME bus, DPRAM and processing sequences about computing and updating values between DSP modules and CPU30 board when the simulator is working.