Role of Innovation, Technology Diffusion and Policies for Sustainable Growth

학위논문 (박사)-- 서울대학교 대학원 : 협동과정 기술경영·경제·정책전공, 2013. 2. 김연배.본 논문의 목표는 기술혁신, 확산, 그리고 정부정책이 청정에너지기술의 지속 가능한 성장에 미치는 영향력을 다양한 모델기법에 의한 실증연구를 통해 규명하고 평가하는데 있다. 연구는 크게 세 부분으로 이루어지는데, 첫째, 청정에너지기술의 확산 특성을 전세계적으로 살펴보고 그 과정에서 발생하는 현상을 실증적으로 분석한다. 즉, 세계 다수의 국가(약 43개국)를 대상으로 에너지절약기술의 효율성 역설 현상을 비모수적 기법으로 모델링하여 분석하는 것이다. 분석결과, 국가 마다 에너지절약 기술의 효율과 혁신역량의 편차가 있으나 전반적으로 북유럽, 서유럽, 북미, 한국, 일본 등이 타 지역에 비해 시장실패효과가 덜한 것으로 나타났으며 교토협약이 체결된 1998년 이후 다수의 OECD국가들이 대외 기술을 흡수하는 역량을 강화하는 것으로 나타났다. 이 같은 분석을 통해 청정에너지의 기술확산은 시장경쟁에 의해 자연적으로 이루어지는 것이 아니라 여러 경제환경, 기술적 요인과 더불어 국제 규범과 각 국가의 정책적 지원이 동반될 때 제대로 이루어 질 수 있음을 확인하였다. 두 번째 연구로서, 정부의 정책적 지원이 필요한 청정에너지기술에서 정책의 효율적인 전략을 수립하기 위해서는 정책의 영향력을 다각도로 평가해 볼 필요가 있다. 이에 본 논문은 OECD국가들의 재생에너지기술을 대상으로 슘페터 이론에 기반한 "발명-혁신-확산"의 3단계로 구성되는 국내 혁신시스템을 모델링하고 혁신시스템 내의 상호작용과 정책의 영향력을 실증적으로 분석한다. 분석결과, 발명-혁신-확산 간에는 선순환 작용이 발생하며, 재생에너지 기술에 따라 정책의 정태 및 동태적 영향력이 달라짐을 확인하였다. 셋째, 재생에너지기술이 환경문제해결을 위한 국내보급에 그치는 것이 아니라 국제무역을 통한 지속가능한 경제발전의 원동력으로 거듭나는 것이 주요 목표이므로 국내 혁신과 국제무역간의 상호관계를 파악하고 국제무역에 정책이 미치는 영향력을 평가하는 것이 중요하다. 따라서, 국내 혁신체계와 수출, 수입간의 상호작용 모델을 구축하고 위에서 열거된 재생에너지 정책이 수출, 수입에는 어떠한 효과를 나타내는지를 파악한다. 분석결과, 기술성숙도가 높을수록 대외무역의 영향을 많이 받으며 기술성숙도가 높은 기술은 시장확대 및 기술확산을 통해 대외수출량을 증가시키고 R&D활동은 수입을 대체하는 것으로 나타났다. 반면, 기술성숙도가 낮은 기술은 국내 R&D를 통해 비용감소에 주력하며 이는 대외수출량에 긍정적인 영향을 미치는 것으로 파악되었다. 정책의 영향력은 태양광의 경우 경쟁을 유도하는 Renewables obligations 정책이 무역량 증가에 긍정적인 반면, 풍력의 경우 환경정책이 국내혁신과 더불어 대외경쟁력에도 긍정적이었다. 본 연구는 기술확산을 실제로 측정하기 어려워 기존연구들이 시장실패를 실증적으로 분석하기 어려웠던 점을 새로운 요인분해분석 기법을 통해 에너지절약기술에 대한 정황적이지만 정량적 증거를 제공함으로써 국가별 시장실패의 정도를 파악하는데 의의가 있다. 또한, 재생에너지의 국내 혁신과 지속 가능한 성장모델을 구축하고 다양한 재생에너지 확대정책의 영향력을 정태 및 동태적으로 살펴봄으로써 다양한 관점에서 정책을 평가할 수 있는 초석을 마련했다는데 의의가 있다.In recent times, investment for developing clean energy technologies is increasing rapidly. However, private R&D investment in this field may be lower than the social optimal level owing to market failures from environmental (e.g., lack of significant pricing policies for GHG emissions) and knowledge (e.g., free-riding by the public-good nature of new knowledge) externalities. To solve these issues and bring forth national innovations, several governments have implemented various technology-push and market-pull policies. The goal of this thesis is to identify the social phenomenon, that is, the market failure-energy efficiency paradox, and assess the impact of government policies on the process of domestic technological change and the foreign competitiveness of clean energy technology, through empirical analyses using a variety of techniques. This thesis is carried out in three parts. First, this thesis analyzes the market failure phenomenon of about 43 countries energy-saving technologies using a non-parametric methodology. Specifically, each countrys country-specific CO2 emission trend is investigated, and the impact of changes in technical efficiency and technological innovation on CO2 emissions is evaluated using an originally developed production-based decomposition method. This analysis enables us to identify quantitatively the market failures of various energy-saving technologies, that is, the energy efficiency paradox phenomenon (stagnated diffusion in energy-efficient technologies). The results show that despite national variation in technical efficiency and innovation capacity, the effect of market failure in Northern Europe, Western Europe, North America, South Korea, and Japan is less than that in other regions, and a number of OECD countries have tried to strengthen their capacities and absorb foreign technologies since 1998 when the Kyoto protocol was introduced. This indicates that when technological advances are made, clean energy technologies do not diffuse naturally, namely, by the simple logic of the market, but are spread following certain international regulations such as the Kyoto protocol, and take place with the continued support for national technology diffusion. Therefore, it is important to find an efficient strategy to harmonize support policies, for which the impact of the policies from various perspectives need to be evaluated. The second research topic is an empirical determination of a domestic innovation system, which consists of three stages, that is, the invention-innovation-diffusion stages, based on the Schumpeter theory, and the interactions in this endogenous technological change system. The empirical analysis is conducted as a panel analysis of the OECD countries renewable energy technologies, that is, their solar PV and wind power technologies, for the period 1991–2007. In addition, this thesis determines the static impact of the governments renewable energy policies, which are classified into five—public R&D, tariff incentives, renewable energy obligations, environmental taxes, and public investment—on each stage of the system. The static impact of the policies enables us to estimate the direct and fixed effect of the policies on each stage, because the interactions between the three stages are not considered, giving us an accurate assessment of the policies. Furthermore, as the dynamics of the policy impacts that form in a virtuous cycle are simulated, one can evaluate the total impact of the policies under the interactions between the three stages. According to the empirical results, the virtuous cycle is formed between the invention-innovation-diffusion stages and the static impact of policies varies according to the renewable energy technologies. In particular, public R&D plays a key role as a support measure motivating innovation. The results of the policy dynamics show that public R&D and tariff incentives have a positive impact on the three stages in the system. In addition, this thesis confirms the view that competition-inducing instruments would play an increasingly important role, as the renewable energy technologies develop further. (Environmental taxes appear to play a positive role in innovations within wind power with highly competitive pricing.) Third, as the renewable energy technologies become the driving force for sustainable economic growth through international trade, it is also important for us to identify the interrelationships between domestic innovations and international trade, and evaluate the impact of the policies on international trade. Therefore, this thesis builds a model to investigate the interactions between domestic innovations and export and import, and determines the effects of the renewable energy policies enumerated above on exports and imports. The results underline the fact that as the renewable energy technologies develop and become more advanced, the dependence of R&D activity on international trade becomes higher, and any further domestic R&D and technological diffusion would lead to increased exports. Specifically, technological development enables the technology with high potentials to improve cost-competitiveness and strengthen foreign competitivenesshowever, market factors dominate the technology with low potentials. In terms of policy impact, the renewable energy obligation to promote a competitive policy has a positive impact on solar PV trade, while tariff incentives have a positive impact on wind power. From the empirical results and the foregoing implications, this thesis proposes a harmonization strategy as follows: the instruments for technology-push such as public R&D and tariff incentives should be made compulsory for both solar PV and wind power. With the use of technology, the policy makers should introduce different competition-inducing instruments, for example, renewable energy obligations for solar PV and environmental taxes for wind power. When the technologies are more competitive and the utilities right to choose a clean energy technology is more strengthened, it would be necessary to consider the competition system by technology. In other words, the renewable energy obligations should be complemented specifying a quota by technology, because until now, environmental taxes have not shown a positive impact on the sustainable growth of solar PV. This thesis would therefore emphasize that the target of policies should be adjusted by technologies, and policies should be diversified for a symmetric development of renewable energy technologies. The significance of this thesis is that it provides quantitative evidence for the existence of country-specific market failures using novel decomposition techniques. In addition, the novelty of this thesis is that it divides the sustainable growth model for renewable energy into a domestic innovation and international trade model, and assesses the long-term dynamics of policy impacts as well as the static impact of policies. This thesis therefore lays the foundation to analyze the policy impacts from a variety of perspectives.Abstract iii Contents viii List of Tables xii List of Figures xiv Chapter 1. Overview 1 1.1 Research Background 1 1.2 Research Objectives 7 1.2.1 Environmental assessment 8 1.2.2 Innovation and policy 9 1.3 General Research Framework 12 1.4 Contributions 16 Chapter 2. Energy Efficiency Paradox in Energy-Use Technology 19 2.1 Introduction 19 2.2 Theoretical Background 24 2.2.1 Environmental data envelopment analysis 24 2.2.2 Decomposition analysis 27 2.3 Empirical Model 30 2.3.1 Production-based decomposition 30 2.3.2 Potential for CO2 emissions mitigation 39 2.4 Data 42 2.5 Result and Discussion 46 2.5.1 Decomposition result 51 2.5.2 International comparison of the potential for emission mitigation 66 2.6 Conclusion 72 Chapter 3. Dynamics of Policy Impacts in Domestic Innovation System of Renewables Technology............ 76 3.1 Introduction 76 3.2 Theoretical Background 82 3.2.1 The technological change system and learning effects 82 3.2.2 Impacts of renewable energy–related policies 86 3.3 Simultaneous Equations 92 3.3.1 Invention model: new idea production by technological learning and knowledge spillovers 92 3.3.2 Innovation model: two-factor learning curves 97 3.3.3 Diffusion model: profit maximization for rational choice 99 3.3.4 Interactions between simultaneous equations 102 3.4 Data and Model Estimation 105 3.4.1 Dependent variables 105 3.4.2 Explanatory variables 114 3.4.3 Estimation method 119 3.5 Empirical Results 121 3.5.1 Estimation results: assessment of interrelations between the stages and static impact of policies 121 3.5.2 Simulation results: The virtuous cycle and dynamic impacts of policies 133 3.6 Conclusion 142 Chapter 4. The Role of Innovation and Policies for Sustainable Growth of Renewable energy Technology....... 145 4.1 Introduction 145 4.2 Theoretical Background 149 4.2.1 R&D activity and international trade 149 4.2.2 Renewable energy policy and international trade 150 4.2.3 Different technological maturity and cost competitiveness in renewables technology 152 4.3 Empirical Model 156 4.3.1 R&D model: knowledge generation by international trade and spillover 156 4.3.2 Trade model: interrelations between domestic innovation system and international trade 158 4.3.3 Aggregated model based on endogenous R&D activity and technological diffusion . 161 4.4 Data 163 4.5 Empirical Results 171 4.5.1 Sustainable system with domestic innovation and international trade 171 4.5.2 Dynamic impact of renewable energy policies for sustainable growth 183 4.6 Conclusion 187 Chapter 5. Conclusions and Implications 190 5.1 Summary of the Results 190 5.2 General Conclusions and Implications 197 Bibliography 206 Appendix 1: The decomposition result by time division 224 Appendix 2: Model comparison for robustness in solar PV 229 Appendix 3: Model comparison for robustness in wind power 235 Appendix 4: The trend of technology and market in renewable energy since mid-2000 241 Abstract (Korean) 244Docto

교정력에 의한 사람 치주인대 세포의 유전자 발현 : RNA-sequencing 연구

본 연구의 목적은 교정력을 적용했을 때, 치주인대 세포에서의 유전자 발현의 변화를 RNA sequencing을 통해 알아보는 것이다. 교정 진단 결과, 발치가 필요한 10명의 환자를 대상으로 연구를 진행하였다. 치주인대 세포가 물리적 자극을 받는 상황을 시뮬레이션 하기 위해 실험군에 교정력을 가하였고, 대조군은 힘을 가하지 않은 채로 두었다. 발치한 세포로부터 치주인대 세포를 분리한 후, geneset enrichment analysis (GSEA), Differential Expressed Gene (DEG) analysis 및 real time PCR 분석을 실시하였다. GSEA 결과 대부분의 유전자 세트들은 세포 주기와 관련되어 있었고, DEG 분석을 통해 13개의 up-regulated genes 과 20개의 down-regulated gene을 찾았다. Real time PCR을 통해 5개의 up-regulated genes 과 6개의 down-regulated genes 이 RNA sequencing 결과와 일치함을 발견하였다. 유전자 기능 탐색을 통해 최종적으로 치주인대 세포의 재생과 관련된 3개의 유전자(CPNE3, OPHN1 and PPM1F)를 찾았다. 교정력이 가해졌을 때, 치주인대 세포 내 CPNE3 및 OPHN1 유전자는 up-regulated 되며, PPM1F 유전자는 down-regulated 된다. 후속적인 연구(예를 들면, knock-out model을 이용한 functional study)를 통해 이러한 3개의 유전자가 직접적으로 치주인대 세포 재생에 영향을 미치는 것을 확인하는 것이 필요하다. The aims of this study were to investigate changes in gene expression of periodontal ligament (PDL) cells after mechanical stimulus and to establish mechanism (signaling pathway) through RNA sequencing. We selected ten patients who required tooth extraction for orthodontic treatment. To stimulate the PDL, orthodontic force was applied to the first premolar for three weeks (the experimental group; n=10), while the first premolar on the other side were left untreated (the control group; n=10). After the PDL cells were isolated from the extracted teeth, gene set enrichment analysis (GSEA), differential expressed gene (DEG) analysis, and real time PCR were performed between the experimental and control groups. GSEA demonstrated that most of the gene sets were related to the cell cycle pathway. In the experimental group, 13 up-regulated genes and 20 down-regulated genes were found compared to the control group through DEG analysis. Real time PCR results confirmed that five up-regulation genes and six down-regulated genes were consistent with RNA sequencing results. We finally ruled out three genes (CPNE3, OPHN1, and PPM1F) which is related periodontal ligament regeneration by these analyses. After mechanical stimulus, CPNE3 and OPHN1 genes are up-regulated and PPM1F gene is down-regulated in periodontal ligament cells. We found the three genes can directly affect periodontal ligament, and further studies are needed to clarify the relationship between mechanical stimulus and periodontal ligament cells.open박