(iv) For the workplace regularly employing workers of number or more listed in the right column of the following table corresponding to categories of industry listed in the medium column of the same table, to appoint at least one as a fulltime safety officer among those appointed to supervise the technical matters concerning the safety among those works set forth in each item of paragraph (1) of Article 10 of the Act. However, in the case of industries falling under category 4 in the same table, this shall be limited only to a workplace in which there have been exceeding 100 cases which h compelled workers to be absent from their work for one day or more due to industrial accidents in the past three years.