• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.515-520
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• 2009

According to the operating characteristics of pump applications, they should exhibit high efficiency and energy saving capabilities throughout the whole operating process. A novel efficiency optimization control strategy is presented here to meet the high efficiency demand of a variable speed Permanent Magnet Synchronous Motor (PMSM). The core of this strategy is the excellent integration of mended maximum torque to the current control algorithm, based on the losses model during the dynamic and the grade search method with changed step by fuzzy logic during the steady. The performance experiments for the control system of a variable speed high efficiency PMSM have been completed. The test results verified that the system can reliably operate with a different control strategy during dynamic and steady operation, and the system exhibits better performance when using the efficiency-optimization control.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.2
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• pp.44-53
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• 1992

Automotive transmission is the principle component of vehicle driving system, which transmits the adjusted engine power. The automation of transmission arises from the annoyance of transmission operation such as the frequent stop/start of vehicle and the shifting transients. The study on the optimal shifting condition for the automation of transmission needs the investigation of shifting transients. However, the dynamic modeling theory during transient period is not well-established. In this study, the techniques of dynamic modeling for the power transmission system with Merrite-Wilson gear train are presented. To predict the shifting transients, a driving simulation program is developed, and the results of the analysis are cross-checked in the field test.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.3
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• pp.151-158
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• 2013

Large generator of power plant is very important. In order to protect large generator from faults, digital protective relay or IED is required. However, all protective relays for generators of the domestic power plant are operated by foreign products. And now, for technological independence from foreign and improvement of import substitution effect, IEDs using domestic technology are being developed. To evaluate performance of developing next-generation power devices, the study of the dynamic characteristics of the power plant, generator system modeling, fault simulation and analysis, should be considered. Specially, To obtain IEEE Standards COMTRADE format for relay operation test, generator system modeling and fault simulation using PSCAD/EMTDC tools must be preceded. Until now, a complete modeling of generator internal windings and fault simulation techniques dose not exist. In this paper, for evaluation performance of relay elements of developing IED, the generator system modeling and various faults simulation using PSCAD/EMTDC tools were performed. And then, the various transient phenomena through obtained relaying signal of developed modeling were analyzed.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.103-111
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• 2008

One of the most popular internal combustion engines is the engine in the transportation device. Power is a parameter that shows the capabilities of an object that gives energy, for example the internal combustion engine. Power in this engine is measured by a device called dynamometer. The CFD (Computational Fluid Dynamic) fluent software was simulated several impeller variables to absorb power of engine. With that result, we knew the biggest dynamometer absorber power, cheapest and easy to be made. The hydraulic dynamometer is selected type of dynamometer as the result of design process. The basic principle of a hydraulic dynamometer is the same as centrifugal pump but it has low pump efficiency. The results of the test are maximum power and torque of the tested engine and the operation area of the selected hydraulic dynamometer.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.19-21
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• 1996

In this paper, the experiment on the dynamic characteristics of LIM for the propulsion system UTM(Urban Transit Maglev) is threated. Untill now LIM has been mainly experimented by using the rotational arch type system, but this system compose of the test vehicle mounted LIM, which driven by PWM inverter. And the anlysis of the performance and the steady-state characteristics of the LIM is treated under various operation patterns. This paper may be available to compose the operating system of LIM driven by the open or closed loop control.

• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1358-1371
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• 2017

Dynamic thermal rating (DTR) system is an effective method to improve the capacity of existing overhead line. According to the methodology based on CIGRE (International Council on Large Electric systems) standard, ampacity values under steady-state heating balance can be calculated from ambient environmental conditions. In this study, simulation analysis of relations between parameters and ampacity is described as functional dependence, which can provide an effective basis for the design and research of overhead transmission lines. The simulation of ampacity variation in different rating scales is described in this paper, which are determined from real-time meteorological data and conductor state parameters. To test the performance of DTR in different rating scales, capacity improvement and risk level are presented. And the experimental results show that the capacity of transmission line by using DTR has significant improvement, with low probability of risk. The information of this study has an important reference value to the operation management of power grid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.212-220
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• 2020

This study examines the effects on isometric lumbar extension strength, dynamic balance ability, and range of motion, after administering 8 weeks SEBT exercise (dynamic balance exercise) and Lumbar Stabilizing exercise, to open laser lumbar microdiscectomy patients. Totally, 14 patients who underwent preservation treatment for 6 weeks after undergoing open laser lumbar microdiscectomy, were enrolled for the study. Patients were randomly assigned to the Lumbar Stabilizing Exercise Group (LSG, n=7) and SEBT Exercise + Lumbar Stabilizing Exercise Group (SGLS, n=7). Results indicate that isometric lumbar extension strength ratio significantly decreases after 8 weeks rehabilitation exercise in both the LSG (p=0.007) as well as SLSG (p=0.024) groups. Normalized reach distance of the three directions in the Y-balance test to examine the dynamic balance capability showed a significant increase in both groups. The dynamic balance capability showed significant increase to the left (LSG, p=0.010; SLSG, p=0.002) and right (LSG, p=0.002; SLSG, p=0.002). Moreover, significant increase was also obtained in the range of joint operation, in both LSG (p=0.006) and SLSG (p=0.017) groups. These results indicate that both groups of rehabilitation exercise achieve positive outcomes on the isometric lumbar extension strength, range of motion, and dynamic balance ability. However, some results suggest that the SEBT program is likely to have a better efficacy.

• The Journal of Korean Association of Computer Education
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• v.4 no.1
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• pp.99-107
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• 2001

One of the main objects of geometry in mathematics education is to improve students' geometric intuition capability and logical reasoning capability based on them. A visual element related to intuition plays an important role in teaching and learning of geometry. Therefore, in this research, we focus on the development of multimedia title available to dynamic operation about visual elements and verify of effect of its application. This title for the learning of "the Pythagorean theorem and its practical use" in the third grade of middle school is designed and implemented by an authoring tool, Toolbook. And it enables learners to study mathematics individually and can be applied to the educational field, too. And we taught two groups, the applied group and the compared one of the second grade of middle school and surveyed Questions and evaluated study achievement. We calculated study achievement of two groups on t-test using SPSS. As the result, we knew that the applied group is higher than the compared one in the study achievement and provision of dynamic operation possibility on visual elements make students know very high learning effect and help improvement of intelligent capability.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.5
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• pp.552-567
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• 2017

The floating crane vessel in waves gives rise to the motion of the lifted object which is connected to the hoisting wire. The dynamic tension induced by the lifted object also affects the motion responses of the floating crane vessel in return. In this study, coupled motion responses of a floating crane vessel and a lifted subsea manifold during deep-water installation operations were investigated by both experiments and numerical calculations. A series of model tests for the deep-water lifting operation were performed at Ocean Engineering Basin of KRISO. For the model test, the vessel with a crane control system and a typical subsea manifold were examined. To validate the experimental results, a frequency-domain motion analysis method is applied. The coupled motion equations of the crane vessel and the lifted object are solved in the frequency domain with an additional linear stiffness matrix due to the hoisting wire. The hydrodynamic coefficients of the lifted object, which is a significant factor to affect the coupled dynamics, are estimated based on the perforation value of the structure and the CFD results. The discussions were made on three main points. First, the motion characteristics of the lifted object as well as the crane vessel were studied by comparing the calculation results. Second, the dynamic tension of the hoisting wire were evaluated under the various wave conditions. Final discussion was made on the effect of passive heave compensator on the motion and tension responses.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.489-497
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• 2016

The rail fastening system, which provides a structural connection between the rail and the sleepers, is a main track component that plays an important role in retaining the rail gauge within acceptable tolerances, as well as in passing the train load to the roadbed through the sleepers. In this paper, a modal test was first performed to evaluate the dynamic characteristics (e.g., natural frequency) of the clips of the railway fastening system under the condition of rail corrugation in urban railway operation. The corrugation-induced passing frequency was then compared with the natural frequency of the clips to investigate any resonance effect during train passage. Furthermore, a field test under train passage was conducted to measure the accelerations on the rail and the rail fastening clips as well as the strains on the rail fastening clips in the rail corrugation condition. The field measurements indicated that the accelerations on the rail and the rail fastening clips have a close relationship with the rail corrugation, but they had a minimal effect on the strains of the rail fastening clips.