By Jihoon Lee and Yena Park SEOUL (Reuters) - South Korea's negotiations with the U.S. on a trade deal to lower tariffs have stalled amid concerns over the foreign exchange implications of a $350 billion investment fund, part of an agreement reached with President Donald Trump in July. WHAT HAS JAPAN AGREED TO? South Korean officials, who had argued that the package would mostly comprise loans and guarantees with limited direct investment, said last week they could not accept terms similar to those of a ...