Question: > 
> 1. Professor required his students to return their papers typed.
> 
> 
> 

vs

> 
> 2. Professor required that his students return their papers typed.
> 
> 
> 

Which of the examples is correct? Do they have the same meaning?
What is the preferred usage?

<http://oxfordlearnersdictionaries.com/us/definition/english/require> and <http://www.thefreedictionary.com/require> do not mention any usage differences

Answer: 
Require is a transitive verb, which means that in either case, we can look for an object later in the sentence. In the first sentence,

> 
> Professor required his students to return their papers typed.
> 
> 
> 

We can diagram everything after "required",

> 
> his students to return their papers typed
> 
> 
> 

as part of the object phrase, which in this case is an infinitive phrase functioning as a noun. The base infinitive is "to return," and we can add the object to expand the infinitive phrase, "to return their papers," and add an adverb (or postpositional adjective, but dynamically here it's probably just an adverb) to make it "to return their papers typed." But you can still go further. Since this infinitive form doesn't have an explicit subject, you can add the subject, "his students to return their papers typed." In fact, this verb, "require," happens to require infinitive objects to have an explicit subject. This is because in the absence of an explicit subject, the subject is assumed to be the subject of the clause. For example,

> 
> Professor wanted to return their papers typed.
> 
> 
> 

In this sentence, since "his students" is not included as the explicit subject, the implicit subject for the infinitive phrase must be "professor."

The object of the sentence can also be a relative clause (signaled by "that") as in

> 
> Professor required that his students return their papers typed.
> 
> 
> 

In this case, the object, what the professor required, is in the relative clause. Just about anything is acceptable as long as the phrase signaled by "that" is an independent clause in the subjunctive mood. You could even drop the word "that" and it would still be correct in some contexts.

My conclusion is that both of these sentences are perfectly acceptable in English. Hope that helps.
A. This is using the subjunctive mood and the subject form "they" of the pronoun:

*The economy requires they **return** to work.*

*That economy requires they **should return** to work.* [this is more frequent in BrE]

E.g.

> 
> Miss Winthorpe's Elopement - Page 82 Christine Merrill - 2010 -
> ‎Preview - ‎More editions
> 
> 
> You may go back, if you wish, and explain to them that economy
> **requires they return** to work
> 
> 
> \_
> 
> 
> 

B. This is using the infinitive and the object form "them" of the pronoun, as per:

> 
> re·quire
> 
> 
> transitive verb
> 
> 
> 6 : to feel or be under the necessity of (doing or being something
> specified) — used **with a following infinitive**
> 
> 
> *one does not require to be a specialist — Elizabeth Bowen*
> 
> 
> *a candidate requires to hold a … certificate — Achievement in the Gold
> Coast*
> 
> 
> Merriam Webster Unabridged Dictionary
> 
> 
> 

*The law required **them** **to return** to work.*

> 
> \*Daily Labor Report - Issues 191-212 - Page 44 1979 -
> 
> 
> Most of the employees met in the lunchroom to discuss whether the
> collective bargaining agreement negotiated by Lumber Production and
> Industrial Workers Local 2573 **required them to return to work**.\*
> 
> 
>