Singapore Expats

I have sent an email to ACS(international) attaching my application and all the required documents to their admissions related email addresses a little less than a month ago after I had visited their open house. I still haven't received any acknowledgement regarding my application, and I'm worried I may have sent my application to the wrong person or department. I was hoping to know whether it's merely a slow process or if there's been an error in my method of application.

It may well depend on their HR departments. HR personnel in Singapore, by far an large, tend to only respond to those that they are interested in. It's nothing personal, but just that they are not to well versed in the niceities of responses. You could always call them as ask what is the proper department or person to send it to, just to confirm you sent it to the right place, then resubmit (even if you sent it to the correct one the first time).