Hi Arifin,
I really like your site and, as everyone else who commented, think it's a great design. The structure has a high visual impact and the information is concise and to the point. I can easily learn about what your business does and that's good.
The only thing I found I had to get used to was that *all* the top menu items lead me to a page that has the large graphic in the main part of the site and that the submenu is at the bottom of the graphic. Visually it looks good, however, it is not what I expect (except on the home page). This is a minor thing anyway but usability evangelists would probably have a word or two to say about this
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As someone else pointed out, the text does need some proof-reading by a native english speaker. I would make that no. 1 on my list of ToDo things to correct on the site. You are striving for professionalism and excellence and you have achieved that with your clean design. Now you only have to correct the grammar and spelling and you're sorted.
Good Luck with your business.