1. Introduction
2. Observational Material
2.1. Sample and Data
2.2. Nuclear Activity
3. Methods
3.1. Strength of Non-axisymmetric Disk Structures
3.2. Central Concentrations of CO Luminosity and Molecular Gas
3.3. Central Concentrations of Star Formation Rate
4. Results
4.1. Profiles of the Molecular Gas Surface Density
4.2. Molecular Gas Concentrations in Barred and Unbarred Galaxies
4.3. Molecular Gas Concentrations and Structure Strength
4.4. Uncertainty from the Bar Identification
4.5. Partial Correlation Coefficients
5. Discussion
5.1. Bar-driven Gas Inflow
5.2. Spiral-driven Gas Inflow
5.3. Gas Inflow Driven by Both Spirals and Bars
5.4. Gas Concentrations in AGN Hosts
5.5. Molecular Gas Concentration and Star Formation Rate Concentration
5.6. Central Concentrations of SFR Driven by Spiral Arms and Bars
6. Summary and Conclusions