Efficiency assessment of Japanese railway business: JR and major private railways QUANTITATIVE ANALYSIS AND MODELING OF FIRMS’ STRATEGIC BEHAVIORS AND PERFORMANCES FROM TECHNOLOGICAL INNOVATION PERSPECTIVES USING PATENT DATA Evaluation Study of Japanese Railway Companies: Impact of COVID-19 and Business Model Perspective Digital innovation in the energy value chain: An analysis of prospects for distributed, renewable energy in Japan Assessment of oil and gas supply chain management and regional differences in efficiency: Application of data envelopment analysis