1 Introduction  
2 Observations and Data Reduction  
2.1 HCN 3-2 Observations with the SMT 10-m Telescope  
2.2 Data Reduction  
2.3 Infrared Data  
2.4 Infrared Luminosities and HCN 3-2 Line Luminosity  
3 Results  
4 Discussion  
4.2 Excitation of HCN Molecules  
4.3 Star Formation Efficiency of Dense Molecular Gas  
5 Summary