Abstract: Disclosed is a method of preparing a copper electroplating layer having high adhesion to a magnesium alloy, which is advantageous because the usability of the magnesium alloy, having the highest specific strength among actually usable metals, can be increased through the development of a process of forming a uniform copper plating layer upon electroplating of the magnesium alloy. The method of preparing a copper electroplating layer having high adhesion to a magnesium alloy of this invention is characterized in that the magnesium alloy is pretreated with a plating pretreatment solution to form a film for electroplating, serving as a magnesium alloy pretreatment layer, exhibiting a uniform current distribution, which is then electroplated with copper to form the copper plating layer. According to this invention, through the pretreatment of the magnesium alloy, the adhesion of the copper plating layer to the film for electroplating formed on the magnesium alloy can be increased.

Abstract: A hand brake with a foldable operation lever comprises a ratchet fixed onto a car frame and an operating lever that can be moved up and down and coupled by a hinge onto the ratchet. It also comprises a push button, a rod coupled to the push button, and a slider coupled to the rod. The slider is located inside the operating lever and forcibly rotates a pawl. The pawl is coupled by a hinge to a rotational body, which allows the operating lever to be selectively locked and released from the ratchet. The operating lever also includes a lever limiter, which limits the rotation of the operating lever.

Abstract: A stereophonic image may be enhanced by splitting the left and right input audio signals into a plurality of left and right output signals in a plurality of audio frequency bands and then generating left and right output audio signals from the left and right output signals based on the magnitude of the differences between corresponding left and right output signals and also based upon the absolute magnitude of the left and right input audio signals themselves. In particular, a stereophonic image enhancement device according to the invention processes a left input signal and a right input signal using a first spectrum analyzer and a second spectrum analyzer which output a plurality of left output signals and right output signals corresponding to a plurality of frequency bands in response to the corresponding left input signal and right input signal.

Abstract: The present invention discloses a calculation method utilizing a circuit and a circuit for obtaining a logarithmic approximation value. The circuit minimizes the error in calculating a logarithmic approximation value by adding a simple circuit. The method includes the steps of obtaining a square value of an input data value, which is greater than or equal to 0 and less than 1. A subtracting step substracts the square value of the input data value from the input data value to obtain a first output result. The first output result is then divided by 4 to obtain a second output result. The input data value is then added to the second output result to obtaining a third output result.