Provided is a hot-dip galvanized steel sheet to be used for home appliances, vehicles, and the like, and having excellent surface appearance and low-temperature bonding brittleness. The hot-dip galvanized steel sheet includes: a base steel sheet; and a hot-dip galvanized layer formed on the base steel sheet. A surface of the base steel sheet has a centerline average roughness (Ra) of 0.3 or more, a roughness skewness (Rsk) of −1 or less, and a roughness kurtosis (Rku) of 6 or more.

Disclosed is a steel sheet for hot press forming, which includes: a base steel sheet; and a plating layer disposed on the base steel sheet and including a diffusion layer and a surface layer that are sequentially laminated, wherein the diffusion layer includes an Fe—Al alloy layer and an Fe—Al intermetallic compound layer that are sequentially disposed on the base steel sheet and each include silicon, and an area fraction of the Fe—Al intermetallic compound layer with respect to the diffusion layer is 84.5% to 98.0%.

An apparatus for controlling coating weight coated on a strip by using an air knife disposed in a travelling direction of the strip in a continuous plating process in which the strip is dipped in a molten metal pot and is coated includes: a prediction model unit including a prediction model in which a neural network is trained with accumulated operation conditions; and an optimum air knife condition calculation unit configured to derive an absolute value of at least one of an air knife gap and an air knife pressure by using the prediction model based on an input operation condition.

An apparatus for controlling coating weight of a steel sheet by using an air knife includes: an air knife condition derivation unit configured to derive a first air knife gap and a final air knife pressure for target coating weight, and derive a second air knife gap for achieving the target coating weight at a current air knife pressure; and an air knife pressure response compensation unit configured to determine a final air knife gap according to a gap compensation amount that is a difference between the second air knife gap and the first air knife gap and a gap compensation ratio based on an air knife pressure variation amount for a control period, in which the control period is a period for updating an air knife condition for the target coating weight.

An apparatus for controlling coating weight of a steel sheet by using an air knife includes: an air knife condition derivation unit configured to derive a first air knife gap and a final air knife pressure for target coating weight, and derive a second air knife gap for achieving the target coating weight at a current air knife pressure; and an air knife pressure response compensation unit configured to determine a final air knife gap according to a gap compensation amount that is a difference between the second air knife gap and the first air knife gap and a gap compensation ratio based on an air knife pressure variation amount for a control period, in which the control period is a period for updating an air knife condition for the target coating weight.

Provided is a plated steel sheet having an excellent quality with fine and even plating texture, the plated steel sheet including a base steel sheet and a Zn plating layer formed on the base steel sheet, wherein a Zn crystal in the plating layer has a size of 5 μm or less.

Provided is a plated steel sheet having an excellent quality with fine and even plating texture, the plated steel sheet including a base steel sheet and a Zn plating layer formed on the base steel sheet, wherein a Zn crystal in the plating layer has a size of 5 μm or less.

Provided are a hot-dipped galvanized steel material and a method for manufacturing the same. The hot-dipped galvanized steel material comprises an iron substrate and a hot-dipped galvanizing layer formed on the iron substrate, wherein the hot-dipped galvanizing layer comprises, by wt %, 0.01 to 0.5% of Al, 0.01 to 1.5% of Mg, 0.05 to 1.5% of Mn, 0.1 to 6% of Fe, and the balance of Zn and inevitable impurities, with a Zn—Fe—Mn based alloy phase present at the interface between the iron substrate and the hot-dipped galvanizing layer, and an area ratio of the Zn—Fe—Mn-based alloy phase to the hot-dipped galvanizing layer ranging from 1 to 60%.

A cooling method of a travelling coated steel strip, exiting a hot-dip coating bath, including the steps of A) sucking a gas into a cooling device, B) filtering the sucked gas by a filtering system capturing at least 50% of the particles having a size of at least 2.5 .Math.m, C) blowing, at a velocity comprised from 1 to 80 m.s.sup.-1, the sucked and filtered gas onto the coated steel strip.

Device for solidifying a coating layer hot deposited on a wire-, corresponding installation and method. The device comprises a cooling liquid injection chamber with a liquid inlet and a wire inlet, a cooling chamber with a liquid outlet and a wire outlet, and a partition arranged between the injection and cooling chambers, comprising a wire passage. It also has a conduit for separating the wire. The partition comprises channels fluidically connecting the injection chamber with the cooling chamber and leading into the center of the wire passage in an eccentric manner and being inclined forming an angle with respect to a longitudinal direction-. This directs a jet of cooling liquid on the wire in the direction from the injection chamber towards the cooling chamber.