As Korea Faces Economic Crisis, Emigrants Feel a Sad Vindication
South Korean immigrants in US, who watched homeland prosper from afar during past decade, find themselves in unaccustomed position of feeling relatively more well-off, as South Korea tries to dig out from staggering currency and economic crisis; many say humbling of homeland has produced unexpected flush of vindication, showing them that burdens of immigrating, such as learning new culture and language, were not mistake; say they feel tortured, distressed and ashamed over country's economic plight; have thrown themselves into various local efforts to show solidarity with austerity drive back home; photos (M)

