The aim of this research is to map the intellectual structure of the field of LED and optics during the period of 2000-2009. We utilize the scientometric tool of co-word analysis to reveal patterns and trends in the LED and optics field by measuring the association strengths of keywords (or IPCs). Data were collected from Science Citation Index Expanded (SCIE) and United Stated Patent and Trademark Office (USTPO) for the period of 2000-2009. Keywords were extracted from abstracts and further standardized using theasarus. In order to trace the dynamic changes of the LED and optics field, the whole 10-year period was separated into two consecutive periods: 2000-2004 and 2005-2009. The results show that the LED and optics field has some established research themes and it also changes to embrace new themes.

This paper explores the leverage impact on cash holdings using the Korean SME data for 134 firms listed in KOSPI market over the period 1980-2008. In theory, the SMEs are different and characterized in terms of higher asymmetric information and more agency cost. We focus on the relation between cash holdings and leverage. We hypothesize that the impact of leverage on cash holdings is more likely to be non-monotonic relation for listed Korean SEMs. It is justified that as leverage of firms act as a proxy for their ability to issue debt, we would expect a negative relation as substitution effect between leverage and cash holdings. However, also it might expect that as leverage increases, firms are likely to save larger cash levels to minimize the risk of financial distress and much costly bankruptcy as well as the threat of default. Thus we would expect that there is a positive relation as precautionary effect between leverage and cash holdings. Our evidences provide that for full period, this relationship is not found, and for IMF crisis, only substitution effect is shown, but for after IMF crisis. However our findings provide strong and robust support for a significant non-monotonic relation between leverage and cash holdings. Therefore, after suffering financial event, SMEs tend to have precautionary motivation for saving cash.