Abstract: The present disclosure relates to an organic electroluminescent compound, a plurality of host materials, and an organic electroluminescent device comprising the same. By comprising the compound according to the present disclosure or by comprising a specific combination of compounds according to the present disclosure as a plurality of host materials, it is possible to produce an organic electroluminescent device having improved driving voltage, luminous efficiency, and/or lifetime properties compared to the conventional organic electroluminescent devices.

Abstract: Disclosed is a method for preparing a reduced graphene oxide-magnesium nanocrystal composite. The method includes contacting graphene oxide with a first reducing agent to prepare a reduced graphene oxide, and co-reducing the reduced graphene oxide and a precursor of magnesium in the presence of a second reducing agent to prepare a reduced graphene oxide-magnesium nanocrystal composite, wherein by adjusting the amount of the first reducing agent in contact with the graphene oxide, the size of the magnesium nanocrystals in the composite may be controlled.

Abstract: An apparatus and a method for controlling an iris. The apparatus includes a data detector, a controller, and an iris controller using a feedback method, and further includes a buffer which stores an amplification ratio for modifying the input video signal to include a proper brightness level when the controller determines that adjustment of the iris is needed. An amplification ratio of 1 is stored when the controller determines that adjustment of the iris is not needed. A multiplier amplifies the input video signal by the amplification ratio stored in the buffer. As a result, a video signal having a proper brightness level is output.