• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.9
• /
• pp.953-960
• /
• 2012

An overhung mounted carrier with flexible pins is applied to the planetary gear train of a wind turbine gearbox to investigate the influence of the self-aligning effect by means of the deflection of the planet spindle and the flexible pin on the lifetime of the planet gear for a wind turbine gearbox. To analyze the load distribution of planet gears, both Euler theory and commercial software are employed. By applying an overhung mounted carrier with flexible pins in the wind turbine gearbox, we can improve the misalignment performance, face load factor, and service life of the planet gears. In particular, it was confirmed that a service life of more than 20 years could be realized for wind turbine gearboxes by applying a flexible pin to the overhung mounted carrier.

• 유체기계공업학회:학술대회논문집
• /
• 2003.12a
• /
• pp.631-638
• /
• 2003

The wind turbine blade is the equipment converted wind into electric energy. The effect of the blade has influence of the output power and efficiency of wind turbine. The design of blade is considered of lift-to-drag ratio, structure, a condition of process of manufacture and stable maximum lift coefficient, etc. This study is used the simplified method for design of the aerodynamic blade and aerodynamic analysis used blade element method. This process is programed by delphi-language. The program has any input values such as tip speed ratio, blade length, hub length, a section of shape and max lift-to-drag ratio. The program displays chord length and twist angle by input value and analyzes performance of the blade.

• The Journal of the Society of Korean Medicine Diagnostics
• /
• v.18 no.1
• /
• pp.33-43
• /
• 2014

Objective I would like to identify when 'If the wind damage people, they feel aversion to wind. If the cold damage people, they feel aversion to cold.(傷風則惡風 傷寒則惡寒)' has appeared and what does this hypothesis have affected. I also researched future scholars' opinions and their criticism on this hypothesis. Methods: 1. Among the books which are related to Cold damage according to the age, books which have original text that has a relationship with this hypothesis were elected. Total of 30 books were elected, and their original text was extracted and analyzed. Results 1. This hypothesis appeared first on Hwalinseo(活人書) in the Song Dynasty, and had lots of impact on future generations. 2. After passing Song, Yuan, and Ming Dynasty, there were some opinions appeared which criticized part of this hypothesis. Dongeuibogam(東醫寶鑑) also tried to correct this hypothesis. 3. Bang Yu-Jip(方有執) of Ming Dynasty straightly opposed this hypothesis on Sanghanronjobyeon(傷寒論條辨)for the first time. It had huge influence in the Qing Dynasty and lots of scholars suggested that this hypothesis lacks persuasion. 4. Just like Qing Dynasty, this hypothesis is not accepted in the books of modern ages. Conclusion This hypothesis appeared in the Song Dynasty for the first time and had lots of influence, but some counter arguments had appeared as time passed, and during Qing Dynasty, this hypothesis lost its creditibility with lots of criticism.

• Wind and Structures
• /
• v.7 no.2
• /
• pp.131-144
• /
• 2004

A technique for the simulation of atmospheric boundary layers in wind tunnels is developed and tested experimentally. The device consists of a grid made of seven horizontal and vertical evenly distributed bars in which air injection holes are drilled in order to influence the flow in the wind tunnel. The air flow in each bar can be controlled independently. Firstly, the device is used together with a rough carpet, which covers the test section floor, in order to simulate the boundary-layer characteristics over an open rural area. Hot-wire measurements, performed at different positions in the test-section, show the capability of the grid in generating the required boundary layer. An acceptable agreement with statistical values of mean velocity and turbulence profiles has been achieved, together with a good span-wise homogeneity. The results are also compared with those of a passive simulation technique based on the use of spires.

• Wind and Structures
• /
• v.27 no.2
• /
• pp.89-100
• /
• 2018

3D simulations based on an impinging jet were carried out to investigate the flow field of a steady downburst and its effects on a high-rise building by applying the SST k-${\omega}$ turbulence model. The vertical profile of radial wind speed obtained from the simulation was compared with experimental data and empirical models in order to validate the accuracy of the present numerical method. Then wind profiles and the influence of jet velocity and jet height were investigated. Focusing on a high-rise building, the flow structures around the building, pressure distributions on the building surfaces and aerodynamic forces were analyzed in order to enhance the understanding of wind load characteristics on a high-rise building immersed in a downburst.

• Fire Science and Engineering
• /
• v.22 no.4
• /
• pp.20-26
• /
• 2008

The performance of natural smoke ventilators in High-rise buildings was analyzed by investigating the stack effect depending on the wind velocities using CONTAMW tool. The results showed that the opening of smoke ventilators can influence on the stack effect in the building thus moving the position of the neutral plane toward the opened smoke ventilators. The outside wind velocities can move up the neutral plane toward the top of the building thus increasing pressure differentials at the bottom of the building. The smoke ventilators can maintain its normal performance without outside wind, however, strong outside wind can prevent natural smoke exhaust due to the infiltration of outside air at the ventilators.

• Wind and Structures
• /
• v.30 no.1
• /
• pp.1-13
• /
• 2020

The loss prediction and assessment during extreme events such as wind hazards is always crucial for the group low-rise residential buildings. This paper analyses the effect of variation in building density on wind-induced loss for low-rise buildings and proposes a loss assessment method consequently. It is based on the damage matrices of the building envelope structures and the main load-bearing structure, which includes the influence factors such as structure type, preservation degree, building density, and interaction between different envelope components. Accordingly, based on field investigation and engineering experience, this study establishes a relevant building direct economic loss assessment model. Finally, the authors develop the Typhoon Disaster Management System to apply this loss assessment methodology to practice.

• Wind and Structures
• /
• v.33 no.6
• /
• pp.423-435
• /
• 2021

Although existing algorithms can predict wind speed using historical observation data, for engineering feasibility, most use moment methods and probability density functions to estimate fitted parameters. However, extreme wind speed prediction accuracy for long-term return periods is not always dependent on how the optimized frequency distribution curves are obtained; long-term return periods emphasize general distribution effects rather than marginal distributions, which are closely related to potential extreme values. Moreover, there are different wind speed parent sample types; how to theoretically select the proper extreme value distribution is uncertain. The influence of different sampling time intervals has not been evaluated in the fitting process. To overcome these shortcomings, updated steps are introduced, involving parameter sensitivity analysis for different sampling time intervals. The extreme value prediction accuracy of unknown parent samples is also discussed. Probability analysis of mean wind is combined with estimation of the probability plot correlation coefficient and the maximum likelihood method; an iterative estimation algorithm is proposed. With the updated steps and comparison using a Monte Carlo simulation, a fitting policy suitable for different parent distributions is proposed; its feasibility is demonstrated in extreme wind speed evaluations at Longhua and Chuansha meteorological stations in Shanghai, China.

• Smart Structures and Systems
• /
• v.17 no.3
• /
• pp.391-411
• /
• 2016

This study investigates the mode identifiability of a multi-span cable-stayed bridge in terms of a benchmark study using stabilization diagrams of a system model identified using stochastic subspace identification (SSI). Cumulative contribution ratios (CCRs) estimated from singular values of system models under different wind conditions were also considered. Observations revealed that wind speed might influence the mode identifiability of a specific mode of a cable-stayed bridge. Moreover the cumulative contribution ratio showed that the time histories monitored during strong winds, such as those of a typhoon, can be modeled with less system order than under weak winds. The blind data Acc 1 and Acc 2 were categorized as data obtained under a typhoon. Blind data Acc 3 and Acc 4 were categorized as data obtained under wind conditions of critical wind speeds around 7.5 m/s. Finally, blind data Acc 5 and Acc 6 were categorized as data measured under weak wind conditions.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.800-804
• /
• 2005

Load flow and short circuit fault transients of a power distribution system with wind turbines as dispersed generation units is presented. Usage of renewable energies such as wind is already a small part of total installed power system in medium and low voltage networks. In this paper, a radial power distribution system with wind turbines is simulated using DIgSILENT PowerFactory software for their influence on load flow and short circuit fault transients. Short fault occurring in dispersed generation systems causes some problems for the system and costumers such as fault level increase or the problems of sudden fluctuations in the current, voltage, power and torque of the double fed induction machine utilized in the wind turbines which have been studied and investigated.