The Economic Achievement of Korea

50 years ago Korea was one of the poorest countries in the world. Our GDP per capita was the lowest level. The Korean government strived to raise economic competitiveness and to develop a growth engine. Exporting by the large manufacturing companies was accepted as the growth propelling model.

In that process, Samsung has become became the most outstanding IT company in the world, and Hyundai Motors has become the representative Asian auto-car producer. Now, we are a member of the G20 Group, and our annual trading amount ranks 5th in the world.

Many countries from southeast Asia are trying to benchmark the Korean Economy's success model.

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1) The + superlative. You wrote "one of THE poorest countries in the world", but you forgot it in "our GDP per capita was lowest level"
2) THE Korean government, THE G20 group

3) In that process, Samsung became the most outstanding IT company. (the process began in the past, so make it past)
Because of that process, Samsung has become the most outstanding IT company. (the process began in the past, but we're stating a recent/continuous effect)