The devaluation of the Japanese yen will have a negative impact on credit quality of South Korean exporters, especially in the steel and electronics industries that are fiercely competing with Japanese rivals, the global rating appraiser said Wednesday. \"With the won\'s rise, automakers, chemical companies and construction companies are most vulnerable because of their large exports in the U.S. dollar,\" Chris Park, Moody\'s vice president, said at a briefing in Seoul. \"And steel and electronics companies are most susceptible to the won\'s rise against the Japanese yen, because they compete with Japanese companies which also export from their home country on a large scale.\" The South Korean currency rose 14.4 percent against the Japanese yen in the first quarter, the highest gain since the second quarter of 2009. Market watchers warned that the weak yen trend will begin influencing negatively the South Korean exports from the second quarter of this year. Park cautioned that negative rating actions will continue to outnumber positive ones in the South Korea\'s private sector over the next 12 months, citing weak growth in key export markets, subdued domestic consumer spending, the won\'s appreciation against the dollar and the yen and aggressive investment strategies by some firms. Around 38 percent of South Korean corporate ratings had a negative outlook as of the end of April, up from 32 percent at the end of 2012 and 25 percent at the end of 2011, according to the Moody\'s. \"Specifically, sluggish demand growth in developed markets and China will hinder recovery of the profitability and cash flow of many Korean exporters of commodity products, particularly of steel and chemicals,\" said Park.