Abstract: Disclosed are an air conditioner and a control method therefor. The air conditioner includes: a main body; a filter configured to filter impurities externally introduced into the main body; a fan configured to introduce the impurities into the main body through the filter; a sensor configured to detect a filter state value for determining a state of the filter; and a processor configured to determine that a replacement time of the filter arrives when an impurity purification capacity calculated on the basis of the filter state value detected in real time by the sensor is lower than a reference value.

Abstract: Disclosed are an air conditioner and a control method therefor. The air conditioner includes: a main body; a filter configured to filter impurities externally introduced into the main body; a fan configured to introduce the impurities into the main body through the filter; a sensor configured to detect a filter state value for determining a state of the filter; and a processor configured to determine that a replacement time of the filter arrives when an impurity purification capacity calculated on the basis of the filter state value detected in real time by the sensor is lower than a reference value.

Abstract: A method for providing a user interface (UI) for playing a multimedia content in a user terminal may include defining a UI area in at least one portion of a display of the user terminal, visually providing a first wheel disposed at one side of the UI area and a second wheel disposed at another side of the UI area, visually displaying playback state information of a multimedia content file being played, in a space between the first wheel and the second wheel, visually displaying a playback control button of the multimedia content file in the UI area.

Abstract: A method of providing a flash card and apparatuses for performing the method are disclosed. A method of providing a flash card in a learning system including a first terminal and second terminals may include creating, by the first terminal, a first flash card associated with a corresponding page of an electronic book (e-book) currently being displayed on a display of the first terminal, and transmitting, by the first terminal, the first flash card to the second terminals.

Abstract: A method for providing a user interface (UI) for playing a multimedia content in a user terminal may include defining a UI area in at least one portion of a display of the user terminal, visually providing a first wheel disposed at one side of the UI area and a second wheel disposed at another side of the UI area, visually displaying playback state information of a multimedia content file being played, in a space between the first wheel and the second wheel, visually displaying a playback control button of the multimedia content file in the UI area.

Abstract: A method of providing a flash card and apparatuses for performing the method are disclosed. A method of providing a flash card in a learning system including a first terminal and second terminals may include creating, by the first terminal, a first flash card associated with a corresponding page of an electronic book (e-book) currently being displayed on a display of the first terminal, and transmitting, by the first terminal, the first flash card to the second terminals.

Abstract: A skate blade angle controlling device fastened to a lower face of a fixing plate having a rectangular, integral projection part. A fastening bolt is screw-fastened through the fixing plate to a fastening nut onto a connection flat provided on an upper face of the skate blade. A pivotally moving part has an open upper face closed by a lower part of the projection part and has one side pivotally mounted on the projection part on a hinge axle. A concave flute of a concave shape is formed in a lower part of the projection part positioned away from the hinge axle. A controlling plate having a fastening hole is inserted into the concave flute. A controlling screw is fastened in the fastening hole from the top to control the pivoting angle of the pivotally moving part by an upward and downward movement of the controlling plate.

Abstract: The skate blade angle controlling device of skates for a short track heightens a contacting force between skate blade and an icy face and prevents from sliding owing to a rotary centrifugal force, to thereby gain a safety cornering play of a player, at maximum by optionally controlling at any time an angle of skate blade fastened to a lower face of a fixing plate so as to match a physical condition of the user so by maintaining maximumly a vertical state of the skate blade against the icy face even under the state that the player leans his body at maximum.