Why I buy Singapore Technologies Engineering?

I bought and sold ST Engineering shares numerous time over the past 12 years. I decided to dig into my record and check the details and these are the details.

2003 - Purchased a lot at $1.81 and sold at $1.96 within the year.
2009 - Purchased 5 lots at $2.38 and sold at $3.10 in 2010. 
2011 - Purchased 10 lots at $2.81 and sold at $3.35 in 2012.
2015 - Purchased 5 lots at $2.985 and sold ???

My purchase in 2003 was of course during a time when I was still clueless about investing. Yes, I made a gain of $100 but that was without any homework done. If I know the financial of the company better, I would have definitely held on to my lot and even buy more at a price below $2.

The subsequent purchases weren't really much better. By 2009, I roughly know what the company does but its business is very much more complex for my simple mind. As you can see from the purchase price each time, it has been creeping up, though the last 2 purchases were below the previous price that I sold. 

So unlike my purchase of Best World, Parkwaylife Reit, Raffles Medical, Straco and Starhill Global Reit, I don't seem to be buying ST Engineering for long term.

Why buy?
Based on its track record, ST Engineering delivered a pretty stable performance. From 2011 to 2015, revenue and net profit is around $6 bil and $5.3 mil respectively. EPS is around 17 to 18 cents and DPS is around 15 cents. 

My assumption is that the company will continue to pay out dividend annually and there won't be much change in the amount of dividend in the coming few years. Hence, I have a sense of comfort buying it whenever the price dropped below $3, as at 15 cents, that give me a good yield of 5%.

What I expect?

I expect that in near term, the revenue and net profit should continue to be stable. There might be a dip as economy seems to be drifting at this moment. The dividend payout should remain pretty stable at 15 cents too.

When will I sell?

I will sell when Mr Market decides to value it higher and provides me a return of at least 3 years of dividend, without any change in its fundamental.

Recent results
20161H revenue grew by 5% and net profit grew by 2%. Management guides that revenue would continue to grow in 20162H but profit before tax will be lower. 5 cents of interim dividend declared which is the same as last year.

Will hold on to my 5 lots and continue to monitor.