• 한국자동차공학회논문집
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• 제3권6호
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• pp.212-223
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• 1995

To improve the efficiency of a power transmission system with slip elements, power split/circulation system is applied. The performance of a power split/circulation system varies widely by the change of the followings; the layout of system, the type and gear ratio of planetary gear, the performance of slip element, etc. Therefore, when one designs such a power transmission system or when one determines the economic/power mode of system, a certain performance prediction method is needed. In this study, the internal power flow pattern of a power split/circulation system is theoretically analyzed on several transmission systems. And an effective performance prediction method(so called performance locus diagram) is presented. By this method, the effects of design factors can be easily understood and the qualitative performances of system can be clearly evaluated.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권4호
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• pp.478-485
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• 2013

This paper focuses on the design and control of a new concept for wind turbines with a planetary gearbox to realize a power split. This concept, where the generated wind power is split into two parts, is to increase the utilization of the wind power and may be particularly suitable for large scale off-shore wind turbines. In order to reduce the cost of the power electronic devices, a synchronous generator, which is driven by the planetary gear, is directly connected to the power grid without electronic converter. A servo drive, which functions as the control actuator, is connected to the power grid by a power electronic converter. With small scale power electronic device, the current harmonics can also be reduced. The speed of the main shaft is controlled to track the optimal tip speed ratio. Meanwhile the speed of the synchronous generator is controlled to stay at the synchronous speed. The minimum rated power of the servo motor and the converter, is studied and discussed in this paper. Different variants of the wind turbine with a planetary gear are also compared. The controller for optimal tip speed ratio and synchronous speed tracking is given.

• 한국공작기계학회논문집
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• 제14권4호
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• pp.96-103
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• 2005

We designed the compound CVT(Continuously Variable Transmissions) by combining power circulation mode and power split mode, which have been proposed for connecting 2K-H I differential gear to the V- belt type CVU(Continuously Variable Unit), as an input coupled type. With the designed compound CVT, we carried out theoretical analysis and performance experiments for efficiency, speed ratio, power flow, and power transmission ratio. We proved that the compound CVT had a better performance than either of the power circulation mode or power split mode.

• International Journal of Precision Engineering and Manufacturing
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• 제6권1호
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• pp.5-14
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• 2005

Continuously variable transmission (CVT) mechanisms combine the functions of a K-H-V type differential gear unit and a V-belt type continuously variable unit (CVU). For the 24 different mechanisms, 12 of them are power circulation modes while the other 12 are power split modes. Some useful theoretical formulas related to speed ratio, power flow and efficiency were derived and analyzed. These mechanisms have many advantages: they decrease CVT size and weight, increase overall efficiency, extend speed ratio range, and generate geared neutral. Compound CVTs were developed by combining the power circulation mode and power split mode, which can offer backward motion, geared neutral, underdrive and overdrive.

• 품질경영학회지
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• 제46권3호
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• pp.651-658
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• 2018

Purpose: The algorithm described in Lim(1998) is available to determine the sample size directly given specified significance level, power and signal-to-noise ratio. We research on the efficient determination of the sample size by visual methods. Methods: We propose three graphs for investigating the mutual relationship between the sample size r, power $1-{\beta}$ and the detectable signal-to-noise ratio ${\Delta}$. First graph shows the relationship between ${\Delta}$ and $1-{\beta}$ for the given r and it can be checked whether the power is sufficient enough. Second graph shows the relationship between r and ${\Delta}$ for the given power $1-{\beta}$. Third graph shows the relationship between r and $1-{\beta}$ for the given ${\Delta}$. It can be checked that which effects are sensitive to the efficient sample size by investigating those graphs. Results: In factorial design, randomized block design and the split plot design how to determine the sample size directly given specified significance level, power and signal-to-noise ratio is programmed by using R. A experiment to study the split plot design in Hicks(1982) is used as an example. We compare the sample sizes calculated by randomized block design with those by split plot design. By using graphs, we can check the possibility of reducing the sample size efficiently. Conclusion: The proposed visual methods can help an engineer to make a proper plan to reduce the sample size.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.311-314
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• 2008

The volume and size of the wind turbine gearbox has been increased with increasing transmitted power. The optimal sizing of gearbox is important due to limited space on the nacelle. The power-split type planetary gear train has been regarded as a better solution than conventional type from the point of view of the volume and weight. The purpose of this paper is to optimize the volume and weight of the gearbox by the analysis of structural characteristics and evaluation of strength of the power-split type planetary gear train.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1060-1068
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• 2002

Compound continuously variable transmission(CVT) mechanisms are proposed, which can offer a backward mode, a geared neutral, an underdrive mode and an overdrive mode. They are composed of a 2K-H I type differential gear unit, a V-belt type continuously variable unit(CVU), a few friction clutches and gears, and not required of a starting device as a torque converter. Compound CVT mechanisms developed here present two distinct operating modes which are a power circulation mode and a power split mode. The transition of two modes takes place at the particular CVU speed ratio. For these CVT mechanisms, performance analysis related to speed ratio, power ratio and efficiency are executed and proven by experimental studies.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.739-742
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• 1997

Continuously variable transmission(CVT) mechanisms are proposed, which can offer a backward mode, a geared neutral, an underdrive mode and an overdriver mode. They are not required of a starting device as a torque converter. CVT mechanisms developed here present two distinct operating modes which are a power circulation mode and a power split mode. The transition of two modes takes place at the particular CVU speed ratio. For these CVT mechanisms, performance analysis related to speed ratio, power ratio and theoretical efficiency are executed.

• 한국전자파학회논문지
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• 제17권11호
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• pp.1132-1142
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• 2006

본 연구는 송전 선로 여러 가지 유형의 극저주파 자기장 저감 적용 모델을 조사하고 그 효과를 분석하였다. 본 연구에서는 154 kV 수평 배열 송전 선로를 기본으로 하여 적용 가능한 다양한 자기장 저감 모델에 대하여 적용시 얻게 되는 자기장 저감지수(Field Reduction Factor)를 검토하였다. 그 결과 compact 모델 채용시에는 상간거리 compact화 비율과 자기장 저감지수가 거의 비례하였으며, diamond 모델 및 transposed 선로 배치의 경우는 50 %에 근접한 자기장 저감이 가능하였다. 배전 선로에 적용이 가능한 삼각형 배열은 33 % 정도, 2회선 split는 50 % 정도 저감 효과가 나타나는 것으로 분석되었으며 수평 multi split 모델의 경우는 80 %까지 자기장 저감을 얻을 수 있었다.

• Structural Engineering and Mechanics
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• 제87권2호
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• pp.137-149
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• 2023

In this study, to explore the working performance of the CFST split spherical node wind power tower, two groups of CFST split spherical joint plane towers with different web wall thicknesses and a set of space systems were analyzed. The tower was subjected to a low-cycle repeated load test, and the hysteresis and skeleton curves were analyzed. ABAQUS finite element simulation was used for verification and comparison, and on this basis parameter expansion analysis was carried out. The results show that the failure mode of the wind power tower was divided into weld tear damage between belly bar, high strength bolt thread damage and belly rod flexion damage. In addition, increasing the wall thickness of the web member could render the hysteresis curve fuller. Finally, the bearing capacity of the separated spherical node wind power tower was high, but its plastic deformation ability was poor. The ultimate bearing capacity and ductility coefficient of the simulated specimens are positively correlated with web diameter ratio and web column stiffness ratio. When the diameter ratio of the web member was greater than 0.13, or the stiffness ratio γ of the web member to the column was greater than 0.022, the increase of the ultimate bearing capacity and ductility coefficient decreased significantly. In order to maximize the overall mechanical performance of the tower and improve its economy, it was suggested that the diameter ratio of the ventral rod be 0.11-0.13, while the stiffness ratio γ should be 0.02-0.022.