a camera configured to generate a formula image by photographing a region including a formula in response to a formula photographing request, and to transmit a character recognition request including the formula image;

a character recognition module configured to read the formula included in the formula image by performing character recognition on the formula image in response to the character recognition request from the camera, and to transmit a learning recommendation request including the formula;

a control module configured to transmit the formula photographing request to the camera, to detect the formula from the learning recommendation request in response to the learning recommendation request of the character recognition module, to transmit a learning topic detection request including the formula, and to transmit a recommendation target display request when receiving a learning recommendation output request in response to the learning topic detection request;

a recommendation target detection module configured to detect a plurality of learning topics as a recommendation target based on the formula included in the learning topic detection request in response to the learning topic detection request of the control module, to set a priority order of the plurality of learning topics detected as the recommendation target based on a concept distance between a learning history and a learning topic, and to transmit the learning recommendation output request including the plurality of learning topics detected as the recommendation target and the priority order to the control module; and

a display configured to output the plurality of learning topics detected as the recommendation target in response to the recommendation target display request of the control module, wherein the display outputs a learning recommendation screen on which the plurality of learning topics are arranged according to the priority order, and

wherein the recommendation target detection module is further configured to:

detect the formula detected from the learning topic detection request, and detect the plurality of learning topics including a concept of the formula, as the recommendation target;

set the concept distance between the learning topic detected as the recommendation target and the learning topic corresponding to the learner's recent learning history, based on the tree map stored in the tree map database; and

set the priority order to the plurality of learning topics based on the concept distance between the learning topic corresponding to the learner's recent learning history and the learning topic detected as the recommendation target.