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Kunsan, South Korea

Howon University is a university located in Gunsan, South Korea. Wikipedia.

In recent years, there has been a growing interest in the use of naturally sourced fibres for use in composites design and manufacture. In this work, a structural design on 1-kW-class horizontal axis wind turbine blade using natural flax fibre composite is performed. The structural design results of flax/epoxy composite blade are compared with the design results of glass/epoxy composite blade. In order to evaluate the structural design of the composite blade, the structural analysis was performed by the finite element method. Through the structural analyses, it is confirmed that the designed blade using natural composite is acceptable for structural safety, blade tip deflection, structural stability, resonance possibility and weight. © 2015 Japan Society for Composite Materials, Korean Society for Composite Materials and Taylor & Francis Source

Park H.,Howon University
Key Engineering Materials | Year: 2016

This study is to investigate the compressive strength of the carbon/epoxy thick laminate after damage. Through damage tolerance of thick laminate is not standardized test because specimens exceed typical specimen thickness described in the ASTM standard, design allowable of thick laminate shall be determined by the experiment to address design criteria of the structure and incorporate functional capability with damage level. In this study, it is performed the research on damage tolerance of thick laminate adopting aircraft structure. The damage tolerance of thick laminates such as no damage and impact damage is evaluated under compression loading. © (2016) Trans Tech Publications, Switzerland. Source

Jung W.-H.,Howon University
Korean Journal of Materials Research | Year: 2011

Thermoelectric power, dc conductivity, and the dielectric relaxation properties of La 2NiO 4.03 are reported in the temperature range of 77 K - 300 K and in a frequency range of 20 Hz - 1 MHz. Thermoelectric power was positive below 300K. The measured thermoelectric power of La 2NiO 4.03 decreased linearly with temperature. The dc conductivity showed a temperature variation consistent with the variable range hopping mechanism at low temperatures and the adiabatic polaron hopping mechanism at high temperatures. The low temperature dc conductivity mechanism in La 2NiO 4.03 was analyzed using Mott's approach. The temperature dependence of thermoelectric power and dc conductivity suggests that the charge carriers responsible for conduction are strongly localized. The relaxation mechanism has been discussed in the frame of the electric modulus and loss spectra. The scaling behavior of the modulus and loss tangent suggests that the relaxation describes the same mechanism at various temperatures. The logarithmic angular frequency dependence of the loss peak is found to obey the Arrhenius law with activation energy of ~ 0.106eV. At low temperature, variable range hopping and large dielectric relaxation behavior for La 2NiO 4.03 are consistent with the polaronic nature of the charge carriers. Source

Jung W.-H.,Howon University
Korean Journal of Materials Research | Year: 2016

The electrical transport properties of La0.5Sr0.5CrO3 below room temperatures were investigated by dielectric, dc resistivity, magnetic properties and thermoelectric power. Below TC, La0.5Sr0.5CrO3 contains a dielectric relaxation process in the tangent loss and electric modulus. The La0.5Sr0.5CrO3 involves the transition from high temperature thermal activated conduction process to low temperature one. The transition temperature corresponds well to the Curie point. The relaxation mechanism has been discussed in the frame of electric modulus spectra. The scaling behavior of the modulus suggests that the relaxation mechanism describes the same mechanism at various temperatures. The low temperature conduction and relaxation takes place in the ferromagnetic phase. The ferromagnetic state in La0.5Sr0.5CrO3 indicates that the electron - magnon interaction occurs, and drives the carriers towards localization in tandem with the electron - lattice interaction even at temperature above the Curie temperature. © Materials Research Society of Korea, All rights reserved. Source

In developed countries, expansion of communication technology has resulted in continual increase in the construction of data centers with high-density cooling loads. Throughout a year, IT equipment installed in a data center generates large and constant cooling load. As a result, data centers may be consuming an ever-growing amount of energy. The cooling system utilizing the energy of outside air is applied universally to reduce data center energy consumption. The application of the cooling system to the outdoor air cooling system of a data center considers that temperature efficiency and ventilation performance vary depending on the type of ventilation system. The displacement and mixed ventilation method can be applied generally to a data center. The efficiency of a ventilation system depends on inside temperature or contaminant concentrations in room and outlets. This study thus aims to evaluate the ventilation performance that varies according to type of ventilation system installed in the data center. Ventilation efficiency is assessed by applying the concept of total air age and considers the fresh air ratio and age of return air. Further, temperature efficiency gained by utilizing temperature difference is used to assess causes for changes in ventilation performance. © 2016, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg. Source

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