No. In English "I concentrate" means to focus attention on something. The verb is used like that for people: I concentrate, you concentrate, etc... In reference to an inanimate object, "to be concentrated" is a technical term for a high percentage of something within a representative mass - usually for chemicals - "This is a concentrated salt water solution." or like that.
yeah, but if I said my brother has been really concentrated on his studies lately, it could be used in that manner. also technically it does not have to be a high percentage, in chem we often talk about things in really low concentrations. (ex: this sodium chloride solution is concentrated at 0.00001M)
You're right about the chemistry bit, I'm sorry :-)
The usage of concentrate you suggested is a phrasal verb though, which is more complicated. I understood that Andrew-Lim was asking about the imperative mode - to instruct someone to concentrate on something - like I assume 집중하십시오 does in this lesson. In English, you would not say, "be concentrated" or "concentrate you", although someone could "be concentrated on" something. Hope that is more clear!