Recent studies on English $L^*$ (low pitch accent) have revealed the difference of changes in acoustic manifestation between utterances produced by Koreans and those produced by native speakers of English. However, not much effort has been made to compare $L^*$ focused constituents and non-focused constituents. At the same time, most previous works on focus realization are lacking in terms of normalization of acoustic measurement. Therefore, this research is dedicated to comparing the $L^*$ focused items and non-focused items realized by Koreans and Americans and to examining the realization of English $L^*$ produced by the two language groups with improved normalization of the acoustic features (F0, intensity and duration). Within-group analysis comparing focused words and non-focused words showed both Americans and Koreans prolonged the $L^*$ focused syllables but the effect size of syllable lengthening made by Koreans was far less than that made by Americans. Furthermore, significant F0 lowering was found in Americans but not in Koreans. However, the effect of intensity change caused by $L^*$ focus was not significant within each group. The effect of focused words was tested between the two groups revealing that Koreans implemented English $L^*$ focus with higher F0, lower intensity and shorter duration than Americans. In the instances in which a significant Group x Focus Location (initial, middle and final of a sentence) interaction was found, further analysis testing the effect of Group on each Focus Location was conducted. The testing showed that the Koreans produced shorter syllables at initial and middle of a sentence and higher F0 at initial of a sentence than Americans. Implications for the intonation training were also discussed.