so that

「so that*」は日本人の学者によってよく誤用される語句です。以下に、特によく見られる誤用例とその修正例を示します。

[誤] In this way, we have devised a treatment so that the cost is reduced by 90%, while the efficacy is virtually unchanged.

[正] In this way, we have devised a treatment such that the cost is reduced by 90%, while the efficacy is virtually unchanged.

[正] In this way, we have devised a treatment for which the cost is reduced by 90%, while the efficacy is virtually unchanged.

[誤] In the present case, both the origin and the term of the loan are unimportant, so that we focus on the principal and interest rate only.

[正] In the present case, both the origin and the term of the loan are unimportant, and for this reason we focus on the principal and interest rate only.

[誤] These are the values of y so that F(t;y) is a monotonically increasing function of t.

[正] These are the values of y for which F(t;y) is a monotonically increasing function of t.

一般的に、「so that」は（副詞として）「for the purpose of」、「in order that」、あるいは（接続詞として）「with the consequence that」、「and therefore (as a necessary consequence)」の類義語として使用されます 。上記の例文においてはこれらのような意味を適用することは不適切です。
以下に「so that」の正しい用法を例示します。

[正] All options were explained in detail, so that the patient could make an informed decision.

[正] The model is then reduced to a single ODE, so that the standard dynamical systems methods can be applied.

[正] The discussion has been modified so that it cannot be misunderstood in the manner stated.
*文法的に、「so that」はその後に副詞節や名詞節を導入する形で用いられますが、その場合「so」はそれぞれ副詞および接続詞となります。名詞節を導入する場合は（文頭に置かれない限り）その前にコンマが必要で、副詞節の場合は不要です。
詳しい解説についてはグレン・パケット：『科学論文の英語用法百科〈第1編〉よく誤用される単語と表現』（京都大学学術出版会，2004）の第116、第119章をご参照下さい。