For the purpose of this subsection, a violation is considered to be a serious violation if there is a substantial probability that death or serious physical harm could result from a condition that exists or a practice, means, method, operation, or process that has been adopted or is in use, unless the employer did not and with the exercise of reasonable diligence could not know of the violation. The Commissioner shall assess a civil penalty against an employer who receives a citation for a serious violation of this title, an order passed under this title, or a regulation adopted to carry out this title. The Commissioner shall assess a civil penalty against an employer who violates a requirement for posting imposed under this title. The Commissioner may assess a civil penalty against an employer who: willfully or repeatedly violates this title, an order passed under this title, or a regulation adopted to carry out this title; or receives a citation for a violation of a provision of this title, an order passed under this title, or a regulation adopted to carry out this title and there is a specific determination that the violation is not of a serious nature. The Commissioner may assess a civil penalty against an employer who does not correct a violation for which a citation is issued within the period set under this title for correction.