Abstract: A photovoltaic power generation system including a solar cell module having a plurality of layers and a sun tracking device to change an incident angle of solar energy upon the solar cell module. The sun tracking device is mounted at one of the layers such that the sun tracking device is combined with the solar cell module into a module.

Abstract: Disclosed herein are a refrigerator and a defrost control method thereof that are capable of sensing an amount of frost formed on an evaporator based on a change amount of absolute humidity in the refrigerator to control a defrost operation. A defrost control method of a refrigerator including a storage chamber and an evaporator to cool the storage chamber, includes sensing absolute humidity in the storage chamber, determining an estimated amount of frost formed on the evaporator using time segments in which the absolute humidity in the storage chamber decreases, and controlling a defrost operation based on the estimated amount of frost. According to the present embodiments, it is possible to perform the defrost operation at the point of time for optimum defrost, thereby maximizing energy efficiency and cooling efficiency.

Abstract: Disclosed are a turbidity sensor, which correctly senses a turbidity of water although the surface of the turbidity sensor is covered with foreign substances, such as scale, and an electric home appliance having the turbidity sensor. The turbidity sensor includes a light emitting part emitting light, a first light receiving part receiving light emitted from the light emitting part and travelling straight, a second light receiving part receiving light emitted from the light emitting part and scattered, and a control unit determining a turbidity of water according to a ratio of the amounts of the light received by the plurality of light receiving parts. The first light receiving part is installed in a direction of directly receiving the light emitted from the light emitting part, and the second light receiving part is installed in another direction of not directly receiving the light emitted from the light emitting part.

Abstract: Disclosed is an air conditioner, in which, when a temperature sensor is rotated, the rotating speed of the temperature sensor is increased or the temperature sensing cycle is elongated in a rotating section where an object does not exist rather than in a rotating section where the object exists. Further, the rotating speed of the temperature sensor is increased or the temperature sensing cycle is elongated if the object is located at a short distance from the air conditioner rather than if the object is located at a normal distance from the air conditioner, and the rotating speed of the temperature sensor is decreased or the temperature sensing cycle is shortened if the object is located at a long distance from the air conditioner rather than if the object is located at a normal distance from the air conditioner.

Abstract: A device to detect a heat source, which can detect position of a heat source faster and more efficiently using a sensor capable of detecting a heat source, a home appliance having such a detecting device and a method of detecting a heat source are disclosed. The heat source detecting method includes performing a first mode to scan an overall area to be searched, performing a second mode to scan at least one specific region included in the area to be searched, and detecting a heat source in the area to be searched by selectively controlling a sensor the first mode and the second mode. Accordingly, a period of renewing position information of a heat source is shortened, and unnecessary detecting operation is eliminated. As a result, the heat source detecting device can more efficiently detect a heat source, using a sensor having limited performance.

Abstract: Disclosed herein are an apparatus and method to detect a heart-rate and an air conditioning system having the apparatus. As peak points of vital signs acquired from a user are detected via determination of a period, a reliable heart rate variability is calculated based on the peak points. As the emotional state of the user can be diagnosed based on vital signs of the user, optimal air-conditioning control according to physical characteristics or emotional state of the user can be accomplished by sequentially controlling a variety of air-conditioning control factors according to the priority thereof until the user becomes comfortable.

Abstract: A spring support structure for reciprocating compressor having a frame unit elastically supported inside a closed container; a reciprocating motor fixed at the frame unit; a compression unit having a piston combined to an armature of the reciprocating motor and a cylinder to be fixed at the frame unit; and a spring unit supporting a spring support provided at the armature or the piston and guiding a reciprocal movement of the piston. The spring unit includes a plurality of front springs supporting one side of the spring support in parallel and a plurality of the rear springs supporting the other side of the spring support. Because the front and rear springs elastically supporting both the armature and the piston are arranged in parallel to overlap with each other for a certain range, the horizontal length of the spring is reduced, resulting in a compact compressor.

Abstract: A spring support (100) structure for reciprocating compressor having a frame unit (40) elastically supported inside a closed container (10); a reciprocating motor (20) fixed at the frame unit (40); a compression unit (30) having a piston (31) combined to an armature (22) of the reciprocating motor (20) and a cylinder (32) into which the piston (31) is slidably inserted to be fixed at the frame unit (40); and a spring unit (100) supporting a spring support (110) provided at the armature (22) or the piston (31) and guiding a reciprocal movement of the piston (31), wherein the spring unit (100) includes a plurality of front springs (51) supporting one side of the spring support (110) in parallel and a plurality of the rear springs (52) supporting the other side of the spring support.