Abstract: A polycarbonate resin including a unit of Chemical Formula 1, a method for preparing the same, a polycarbonate resin composition including the same, and a molded article including the polycarbonate resin composition are described: wherein all the variables are described herein.

Abstract: A resin including a unit represented by Chemical Formula 1, a method for preparing the same, a resin composition including the same, and a molded article including the resin composition is described: wherein all the variables are described herein.

Abstract: Provided are a chromium catalyst precursor, an ethylene oligomerization catalyst including the same, and a method of preparing an ethylene oligomer using the same. More particularly, a chromium catalyst precursor which may oligomerize ethylene with high activity and high selectivity in spite of not using methylaluminoxane (MAO) or modified-methylaluminoxane (MMAO), an oligomerization catalyst including the same, and a method of preparing an ethylene oligomer using the same are provided.

Abstract: According to the exemplary embodiments of the present invention, there is provided a blockchain based authentication and transaction system including a user DID (Distributed Identity) wallet which is an application program installed on a user's mobile terminal. Here, the user DID wallet allows a user to ascertain whether a counterpart is a legitimate party by verifying a counterpart's VP and expressing the verified counterpart ascertainment information to the user on a screen when the counterpart's VP provided from a counterpart system which is an authentication or transaction counterpart is obtained.