Korea Institute of Science and Technology

Frontics, Inc.

Kwang-Ho Kim

Hoon Sik Kim

Young-Chul Kim

Joo-won Lee

Byeong-kwon Ju

Jung-Suk Lee

Yeol Choi

Jai-Kyeong Kim

Yang-Won Seo

The present invention relates to a method of evaluating the fracture toughness of a material using the continuous indentation technique. In the method of this invention, the stress coefficient, strain hardening modulus and yield stress of the material are determined using the continuous indentation technique and, thereafter, the reduced elastic modulus (Er) of the material is calculated. The effective elastic modulus and the initial elastic modulus are calculated and, thereafter, the damage parameter is calculated using the void volume fraction. The critical elastic modulus and the characteristic fracture initiation point of the indentation depth are determined using the damage parameter and, thereafter, the fracture toughness of the material is evaluated. The present invention is advantageous in that the fracture toughness of a brittle material can be evaluated precisely using a nondestructive evaluation technique.

Evaluating method of the fracture toughness using the continuous indentation method

The present invention discloses an inorganic thin layer which is composed of an inorganic composite containing at least two kinds of inorganic materials and shows excellent moisture and oxygen proof, an organic electroluminescence device including the inorganic thin layer as a passivation layer, and a fabrication method thereof.

Inorganic thin layer, organic electroluminescence device including the same, and fabrication method thereof

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Seoul, South Korea

Kwang-Ho Kim