• Journal of international Conference on Electrical Machines and Systems
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• 제3권3호
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• pp.276-281
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• 2014

The electric power conversion system constructed by connecting two or more power converters in parallel is an advantageous method for making to large capacity and standardization. In this paper, the control method of cross current when three power converters are operated is examined, and it reexamined a preferable system construction method.

• 디지털융복합연구
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• 제3권2호
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• pp.9-22
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• 2005

A large scale automated material handling system (AMHS) is simulated using real industrial input data to analyze its performance so that one can scrutinize the critical factors that affect the AS /RS performance. The factors included in this study are line balancing efficiency, the distance between machines, and cycle time of the machines. The performance of AS /RS is measured in terms of R/M utilities that are latter used to classify the AS/RS structure into three types such as Good, Normal, and Poor. Among the three factors considered in this study, the line balance efficiency within each AS/RS is found as the most critical factor which statistically affect the AS/RS performance.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2005년도 추계학술대회
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• pp.411-424
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• 2005

A large scale automated material handling system (AMHS) is simulated using real industrial input data to analyze its performance so that one can scrutinize the critical factors that affect the AS/RS performance. The factors included in this study are line balancing efficiency, the distance between machines, and cycle time of the machines. The performance of AS/RS is measured in terms of R/M utilities that are latter used to classify the AS/RS structure into three types such as Good, Normal, and Poor. Among the three factors considered in this study, the line balance efficiency within each AS/RS is found as the most critical factor which statistically affect the AS/RS performance.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.154-158
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• 2013

Reduction of electromagnetic vibration and acoustic noise from three-phase squirrel-cage induction motors (IMs) is very important, particularly from the standpoint of environmental considerations. Although the electromagnetic vibration of IMs has been studied for several years, the relationships between the radial distribution of the electromagnetic vibration and noise and the electromagnetic forces responsible for them have not yet been analyzed in sufficient detail. In the present study, we investigated this relationship experimentally for a small IM under different load conditions. Our results clearly show that the radial distributions of the dominant electromagnetic vibration and noise components match the mode shape of the dominant electromagnetic force producing these components.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.48-53
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• 2014

In December 2011 and July 2012, two sets of 840MVA hydro-generator of Three Gorges on Yangtze River with Close-loop-self-circulating evaporative cooling (CLSCEC) system were put into commercial operation. In this paper, we make engineering summary of these two generators with CLSCEC system. We also make a comparison between the internal water cooling (IWC) hydro-generator and the CLSCEC hydro-generator used in Three Gorges power plant in fields of their operating characteristics, working performances, technical features, working safety and reliability. In addition, engineering structures, type tests' results and systematic emulating calculation of CLSCEC schemes are analyzed.

• Safety and Health at Work
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• 제10권4호
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• pp.461-469
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• 2019

Background: Collisions involving workers and mobile machines continue to be a major concern in underground coal mines. Over the last 30 years, these collisions have resulted in numerous injuries and fatalities. Recently, the Mine Safety and Health Administration (MSHA) proposed a rule that would require mines to equip mobile machines with proximity detection systems (PDSs) (systems designed for automated collision avoidance). Even though this regulation has not been enacted, some mines have installed PDSs on their scoops and hauling machines. However, early implementation of PDSs has introduced a variety of safety concerns. Past findings show that workers' trust can affect technology integration and influence unsafe use of automated technologies. Methods: Using a mixed-methods approach, the present study explores the effect that factors such as mine of employment, age, experience, and system type have on workers' trust in PDSs for mobile machines. The study also explores how workers are trained on PDSs and how this training influences trust. Results: The study resulted in three major findings. First, the mine of employment had a significant influence on workers' trust in mobile PDSs. Second, hands-on and classroom training was the most common types of training. Finally, over 70% of workers are trained on the system by the mine compared with 36% trained by the system manufacturer. Conclusion: The influence of workers' mine of employment on trust in PDSs may indicate that practitioners and researchers may need to give the organizational and physical characteristics of each mine careful consideration to ensure safe integration of automated systems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.996-1001
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• 2006

Automatic washing machines have been improved and popularized steadily since the first electric washing machine was produced in the early 1900's. Appliance industry has tried to obtain the performance of washing machine with large capacity, high energy efficiency, low vibration and low noise levels. As the installation peace of a washer becomes closer to the living space, vibration and noise problems become more important challenges. In general, a washing machine has four legs to support its body. Four legs of the washing machine should be attached on a floor. If not so, it may cause severe vibration or walking in the spin-drying process. Unfortunately, the floor of an ordinary house is bumpy in general, and the consumers will not accept bolting washing machines to a foundation; moreover, sometimes they move the location of their washing machines to utility rooms or bath rooms or kitchens and don't care for leveling the legs exactly. In this study, we devise an auto-leg system that prevents the occurrence of abnormal vibration and walking of washing machines. It is simply composed of a spring and a friction damper. Some experiments are implemented to show the dynamic characteristics of the three-dimensional auto-legged washing machine model that is located on the even or uneven ground. A spring parameter is optimized to adjust the length of the auto-leg system automatically up to 10 mm irregularity, and the friction damper is designed to decrease a resonance induced by the spring of the auto-leg system. Some numerical results show that placing the proposed auto-leg system in a washing machine makes good performance with low vibration, as well as low noise, regardless of the unevenness of the floor.

• 로봇학회논문지
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• 제14권4호
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• pp.340-347
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• 2019

Due to advances in machine intelligence and increased demands for autonomous machines, the complexity of the underlying software platform is increasing at a rapid pace, overwhelming the developers with implementation details. We attempt to ease the burden that falls onto the developers by creating a graphical programming framework we named Splash. Splash is designed to provide an effective programming abstraction for autonomous machines that require stream processing. It also enables programmers to specify genuine, end-to-end timing constraints, which the Splash framework automatically monitors for violation. By utilizing the timing constraints, Splash provides three key language semantics: timing semantics, in-order delivery semantics, and rate-controlled data-driven stream processing semantics. These three semantics together collectively serve as a conceptual tool that can hide low-level details from programmers, allowing developers to focus on the main logic of their applications. In this paper, we introduce the three-language semantics in detail and explain their function in association with Splash's language constructs. Furthermore, we present the internal workings of the Splash programming framework and validate its effectiveness via a lane keeping assist system.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.176-183
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• 2014

Three-phase four-wire distribution systems are used for both three-phase three-wire loads and single-phase two-wire consumer appliances in South Korea, Myanmar and other countries. Unbalanced load conditions frequently occur in these distribution systems. These unbalanced load conditions cause unbalanced voltages for three-phase and single-phase loads, and increase the loss in the distribution transformer. In this paper, we propose constant DC capacitor voltage control based strategy for the active load balancer (ALB) in the three-phase four-wire distribution systems. Constant DC capacitor voltage control is always used in active power line conditioners. The proposed control strategy does not require any computation blocks of the active and reactive currents on the distribution systems. Balanced source-side currents with a unity power factor are obtained without any calculation block of the unbalanced active and reactive components on the load side. The basic principle of the constant DC capacitor voltage control based strategy for the ALB is discussed in detail and then confirmed by both digital computer simulations using PSIM software and prototype experimental model. Simulation and experimental results demonstrate that the proposed control strategy for the ALB can balance the source currents with a unity power factor in the three-phase four-wire distribution systems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.869-874
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• 2004

The inverse kinematics of five-axis milling machines produce large errors near stationary points of the required surface. When the tool travels cross or around the point the rotation angles may jump considerably leading to unexpected deviations from the prescribed trajectories. We propose three new algorithms to repair the trajectories by adjusting the rotation angles in such a way that the kinematics error is minimized. Given the tool orientations and the inverse kinematics of the machine, we first eliminate the jumping angles exceeding ${\pi}$ by using the angle adjustment algorithm, leaving the jumps less than ${\pi}$ to be further optimized. Next, we propose to apply an angle switching algorithm to compute the rotations and identify an optimized sequence of rotations by the shortest path scheme. Further error reduction is accomplished by the angle insertion algorithm based an o special interpolation to obtain the required rotations near the singularity. We have verified the algorithms by five-axis milling machines, namely, MAHO600E at the CIM Lab of Asian Institute of Technology and HERMLE UWF902H at the CIM Lab of Kasetsart University.