• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.19-25
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• 2012

About supply and demand to see that you need to match, the limitations of wind power capacity is low demand and the commitment of the general generator will exist between the minimum generation. if the turbine's output can be controlled, The limitation of wind power capacity will be adopted based on instant power generation. Namely, The minimum limits of wind power generation based load operation by calculating the amount that is higher than if the output should be restricted to highest operation. in this paper, we committed to the demand for low enough that the combination of the general generator of wind power capacity to accommodate the operation of determining whether the limit is intended to. For this, power system analysis program PSS/E was used, Jeju system by implementing the model simulations were performed.

• Structural Engineering and Mechanics
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• v.7 no.2
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• pp.217-224
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• 1999

A semi-stochastic process model of reliability was established for hyperbolic cooling towers subjected to combined loadings of wind force, self-weight, temperature loading. Effect of the soil-structure interaction on reliability was evaluated. By involving the gust factor, an equivalent static scheme was employed to convert the dynamic model to static model. The TR combination rule was used to consider relations between load responses. An analysis example was made on the 90M cooling tower of Maoming, Guangdong of China. Numerical results show that the design not including interaction turns to be conservative.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.658-663
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• 2011

The purpose of this study is to develop an air-passing soundproofing panel with more improved structure to reduce the $CO_2$ emission and installation cost. To reduce the emission of $CO_2$ ; it is suggested to choose low $CO_2$ emission material relative to the aluminum and to reduce the materials by developing a specially designed air-passing soundproofing panel structure. First of all, we performed the flow analysis to predict the wind pressure according to the open angle of the air-passing soundproofing panel and the noise level analysis at the receiver point. To verify the simulation, a prototype of the soundproofing panel was made. The flow test in the wind tunnel and load test were performed. The economic evaluation for the installation of the air-passing soundproofing panel was performed and specifications of the installation was prepared. As the results of this research, it was verified that the wind load was reduced about 40% to that of the conventional one at 25m/s wind speed in the wind tunnel test. By applying the 4m span soundproofing wall with air-passing soundproofing panel and under the cost of 250 thousand $won/m^2$ instead of the conventional 2m span panel, the installation cost will always be lowered than the conventional one in the combination of (60:40~50:50) conventional to air-passing soundproofing panel from the economic evaluation. The 20% reduction of $CO_2$ was found by changing the 50% of aluminum soundproof panel to air-passing soundproofing panel.

• Wind and Structures
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• v.8 no.5
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• pp.343-356
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• 2005

Overhead sign support structures number in the tens of thousands throughout the trunk-line roadways in the United States. A recent two-phase study sponsored by the National Cooperative Highway Research Program resulted in the most significant changes to the AASHTO design specifications for sign support structures to date. The driving factor for these substantial changes was fatigue related cracks and some recent failures. This paper presents the method and results of a subsequent study sponsored by the Michigan Department of Transportation (MDOT) to develop a relative performance-based procedure to rank overhead sign support structures around the United States based on a linear combination of their expected fatigue life and an approximate measure of cost. This was accomplished by coupling a random vibrations approach with six degree-of-freedom linear dynamic models for fatigue life estimation. Approximate cost was modeled as the product of the steel weight and a constructability factor. An objective function was developed and used to rank selected steel sign support structures from around the country with the goal of maximizing the objective function. Although a purely relative approach, the ranking procedure was found to be efficient and provided the decision support necessary to MDOT.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1599-1606
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• 2011

It is possible to study the load characteristics of full-scale hingeless rotor with the changing of physical smallscaled configurations such as rectangular and paddle blades, and metal and composite hubs. In this study, a static test, and a ground and wind-tunnel test were carried out using small-scale rotor models. The static test was carried out to confirm structural stiffness, characteristics of inertia, natural frequency, and damping ratio of rotors, and the ground and wind-tunnel test was carried out to confirm the stability and aerodynamic characteristics under hovering and forward flight conditions. According to the test results, the vertical load in the case of a combination of a small composite hub with paddle blades was higher than that in the case of a metal hub with paddle blades at same condition. Further, it was confirmed that the restraint of the combination of composite hub can be more flexible than the metal hub for the motion of paddle blades.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.3
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• pp.353-359
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• 2019

In this study, a aerodynamic loads prediction to design a deploying device of folded fin was introduced. In general, resultant flow conditions around the fin are used to obtain deploying moments and required energy. However, when it comes to the air vehicles launched from a mobile platform, more specific flow conditions can be provided. With the conditions, the design criteria can be calculated more realistically. In this study, therefore, aerodynamic moments induced by aerodynamic loads and energy required in deployment were calculated using wind-over-deck(WOD) velocity, combination of a platform velocity and a wind velocity. For the calculation, wind tunnel test was conducted on various angle of attack, side slip angles, and folding angles. It was found that the aerodynamic moments and the energy required in deployment using the non-uniform flow due to the velocity components were less than those using the uniform flow without the components.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.116-124
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• 2020

In order to analyze the lateral-load resisting capability according to the core locations, three-dimensional structural analyses were performed for 20-story buildings with symmetric plan. Four analytical models for a center core, a single-axial eccentric core, and a double-axial eccentric core were constructed, and eigenvalue analyses, wind-load analyses, and earthquake-load analyses were performed. Torsion did not occur in the central core building, but the bending and torsion occurred in combination with the arrangement of the eccentric core, and the lateral-load resisting capability was degraded. The change in the wind load according to the eccentric core was small, but the maximum lateral displacement was found to increase greatly by the eccentric arrangement of the core. In addition, in case of the eccentric core, the seismic load was slightly reduced compared to the center core due to the decrease in the lateral stiffness, but it was found that the maximum story drift ratio increased significantly due to the torsional effect. Based on these results, the structural behavior according to the position of the core can be clearified and used as a guideline for core locations in the planning and design stage.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.677-688
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• 2021

The building design codes and standards in many countries usually are either fully or partially adopted from the international codes. However, regional conditions like the quality of construction industry and different statistical parameters of load and resistance have essential roles in the code calibration of building design codes. This paper presents a probabilistic approach to assess the reliability level of adopted national building codes by simulating design situations and considering all load combinations. The impact of the uncertainty of wind and earthquake loads, which are entirely regional condition dependent and have a high degree of uncertainty, are quantified. In this study, the design situation is modeled by generating thousands of numbers for load effect ratios, and the reliability level of steel elements for all load combinations and different load ratios is established and compared to the target reliability. This approach is applied to the Iranian structural steel code as a case study. The results indicate that the Iranian structural steel code lacks safety in some load combinations, such as gravity and earthquake load combinations, and is conservative for other load combinations. The present procedure can be applied to the assessment of the reliability level of other national codes.

• Wind and Structures
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• v.27 no.1
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• pp.11-27
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• 2018

The straight-cone steel cooling tower is a novel type of structure, which has a distinct aerodynamic distribution on the internal surface of the tower cylinder compared with conventional hyperbolic concrete cooling towers. Especially in the extreme weather conditions of strong wind and heavy rain, heavy rain also has a direct impact on aerodynamic force on the internal surface and changes the turbulence effect of pulsating wind, but existing studies mainly focus on the impact effect brought by wind-driven rain to structure surface. In addition, for the indirect air cooled cooling tower, different additional ventilation rate of shutters produces a considerable interference to air movement inside the tower and also to the action mechanism of loads. To solve the problem, a straight-cone steel cooling towerstanding 189 m high and currently being constructed is taken as the research object in this study. The algorithm for two-way coupling between wind and rain is adopted. Simulation of wind field and raindrops is performed with continuous phase and discrete phase models, respectively, under the general principles of computational fluid dynamics (CFD). Firstly, the rule of influence of 9 combinations of wind sped and rainfall intensity on flow field mechanism, the volume of wind-driven rain, additional action force of raindrops and equivalent internal pressure coefficient of the tower cylinder is analyzed. On this basis, the internal pressures of the cooling tower under the most unfavorable working condition are compared between four ventilation rates of shutters (0%, 15%, 30% and 100%). The results show that the 3D effect of equivalent internal pressure coefficient is the most significant when considering two-way coupling between wind and rain. Additional load imposed by raindrops on the internal surface of the tower accounts for an extremely small proportion of total wind load, the maximum being only 0.245%. This occurs under the combination of 20 m/s wind velocity and 200 mm/h rainfall intensity. Ventilation rate of shutters not only changes the air movement inside the tower, but also affects the accumulated amount and distribution of raindrops on the internal surface.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.479-484
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• 2000

In this study, optimal design of reinforced concrete piers under seismic load is numerically investigated. Object function is the area of the concreate-section. Design variables are the total area of reinforcement and concrete-section dimension(Circular section diameter). Constraints of the design strength of the column, longitudinal reinforcement ratio and lower and upper bounds on the design variables are imposed. The reinforcement concrete column is analysed and designed by the Ultimated Strength Design method and load combination involving dead, live, wind and seismic load is used. For numerical optimization, ADS(Garret N, Vanderplaats_ routine is used. From the result of numerical examples, the concrete-section dimension was reduced, but longitudinal reinforcement was not changed. The results show that confinement reinforcement was reduced and confinement reinforcement spacing is increased. The higher strength of reinforcement used, the more concrete-section area was reduced.