• New & Renewable Energy
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• v.20 no.2
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• pp.2-16
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• 2024

Various loads induced by marine environmental conditions, such as waves, currents, and wind, are crucial for the operation and viability of offshore wind power (OWP) systems. In particular, waves have a significant impact on the stress and fatigue load of offshore structures, and highly reliable design parameters should be derived through extreme value analysis (EVA) techniques. In this study, extreme wave analyses were conducted with various Weibull distribution models to determine the reliable design parameters of an OWP system suitable for the Ulsan area. Forty-three years of long-term hindcast data generated by a numerical wave model were adopted as the analyses data, and the least-squares method was used to estimate the parameters of the distribution function for EVA. The inverse first-order reliability method was employed as the EVA technique. The obtained results were compared among themselves under the assumption that the marginal probability distributions were 2p, 3p, and exponentiated Weibull distributions.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.173-177
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• 2021

In this study, the torsional rigidity and durability of the stabilizer models with the hollow axis of light and large sized cars were compared and investigated each other. Model 1 was applied with the moment more than three times as much as model 2, but the maximum deformation of model 1 was seen to be about 2.6 times larger than that of model 2. Commonly, models 1 and 2 are seen to get the most stress at the neck of stabilizer bar link. Also, the maximum stress of model 1 was about 2.9 times larger than that of model 2. Model 1 at large car showed more than 20 times more deformed energy than model 2 at small car. Overall, it could be examined that the deformation energy of the bracket part on the side where the moment fixing the stabilizer bar was applied was greater than that of the stabilizer. It is thought that the analysis results in this study can be helped at the design of its convergent research as a durable component of the stabilizer at a light or large sized car.

• Journal of Energy Engineering
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• v.22 no.1
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• pp.28-37
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• 2013

Stirred tank is widely used in various industries for mixing operations and chemical reactions for single- or multi-phase fluid systems. For designing agitator of high performance, quantity data of internal flow characteristics influenced by mixing performance are definitely confirmed but quantity analysis about the transient flow characteristics of complicate structure is recognized as difficult problem in the present. In this study, two models of commercial CFD code Fluent 6.3 used to propose suitable for the tank analysis. Agitation of Stirred tank is analyzed using a mixed model and the flow in the stirred tank is analyzed using a standard k-${\varepsilon}$ model. Multiple reference frame(MRF) and Sliding mesh(SM), the analysis techniques were used For compare a result of CFD with a visualization experiment result, to grasp internal flow and mixing characteristic in stirred tank and to present fundamental analysis method.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.821-827
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• 2015

This study concentrates on a wave energy converter with floaters that extracts the ocean's energy by moving up and down with the wave motion. The floater is connected to an arm structure, including a hydraulic cylinder that drives a hydraulic generator. This study focuses on a structural analysis of the floater unit, including arm and cylinder components, platform and jack-up system, along with spud columns. Previous studies have been conducted for miniature models for experimentation, but this study focuses on the full-scale model structural analysis. Static structural analysis is conducted using fine numerical grids. Due to the complexity of the whole model, it is analyzed in separate pieces. The floater unit, with arm and cylinder, are combined into one system. The platform is analyzed separately as a single system. There are four jack-up systems for each spud column; only one jack-up system is analyzed, as uniform loads are assumed on each system. There are several load cases for each system, all of which are analyzed thoroughly for stress (von Mises, shear, and normal) and deformation. Acceptable results were obtained for most of the components; unsafe components were redesigned.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.3
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• pp.107-115
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• 2002

This parer presents the analysis of hot gas flow in puffer-type circuit breakers using FVFLIC method. For the analysis of arc-flow interaction, the flow field is analyzed from the equations of conservation for mass, momentum and energy with the assumption of local thermodynamic equilibrium state. The arc is represented as the energy source term composed of ohmic heating and radiation term in the energy conservation equation. Ohmic heating is computed by the electric field analysis only within the conducting plasma region. An approximate radiation transport model is employed for the evaluation of emission and absorption of the radiation. The analysis method was applied to the real circuit breaker model and simulation results such as pressure rise and arc voltage were compared with the experimental ones.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.98-100
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• 1999

A thermal analysis was performed for the electromagnet which is installed in the control element drive mechanism(CEDM) of the integral reactor SMART. A model for the thermal analysis of the electromagnet was developed and theoretical bases for the model were established. It is important that the temperature of the electromagnet windings be maintained within the allowable limit of the insulation, since the electromagnet of CEDM is always supplied with current during the reactor operation. So the thermal analysis of the winding insulation which is composed of polyimide and air were performed by finite element method. The thermal properties obtained here will be used as input for the optimization analysis of the electromagnet.

• Journal of The Korean Association For Science Education
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• v.7 no.1
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• pp.41-51
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• 1987

The contents which is related to energy in current science textbooks of high school have been investigated. Based on the analysis of the results, we attempt to develop a model of energy curriculum on high school level.

• Convergence Security Journal
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• v.7 no.4
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• pp.43-50
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• 2007

Electric quantity of sensor nodes is extremely limited, and the battery replacement is very difficult in wireless sensor networks. This paper proposes analytic model on energy loss in different route structure, which it is based upon the data-centric storage and the directed diffusion is energy consumption in the wireless sensor network.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.2
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• pp.66-77
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• 2018

This paper presents a parametric study on an oscillating water column (OWC) wave energy converter (WEC). This OWC has been planned for installation in the breakwaters on isolated islands located away from the mainland. Both a numerical analysis and a model experiment are utilized for determining a proper conceptual design for this purpose. Various design parameters, including the configurations and dimensions, are evaluated through the numerical analysis, which is based on a potential flow theory, and several design concepts are then selected as candidates. The model experiment using a 2D wave flume is conducted to evaluate the effects of the design parameters and compare the performances of the candidates. Based on the overall results of the numerical analysis and model experiment, a conceptual design of the OWC WEC applicable to a breakwater is selected.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.544-544
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• 2014

Energy harvesting technology, which scavenges electric power from ambient, otherwise wasted, energy sources, has been explored to develop self-powered wireless sensors and possibly eliminate the battery replacement cost for wireless sensors. Among ambient energy sources, vibration energy can be converted into electric power through a piezoelectric energy harvester. For the last decade, although tremendous advances have been made in design methodology to maximize harvestable electric power under a given vibration condition, the research in reliability assessment to ensure durability has been stagnant due to the complicated nature of the multiple failure modes of a piezoelectric energy harvester, such as the interfacial delamination, fatigue failure, and dynamic fracture. Therefore, this study presents the first-ever system reliability analysis for multiple failure modes of a piezoelectric energy harvester using the Generalized Complementary Intersection Method (GCIM), while accounts for the energy conversion performance. The GCIM enables to decompose the probabilities of high-order joint failure events into probabilities of complementary intersection events. The electromechanically-coupled analytical model is implemented based on the Kirchhoff plate theory to analyze its output performances of a piezoelectric energy harvester. Since a durable as well as efficient design of a piezoelectric energy harvester is significantly important in sustainably utilizing self-powered electronics, we believe that technical development on system reliability analysis will have an immediate and major impact on piezoelectric energy harvesting technology.