관행농과 유기농의 에너지 사용과 온실가스배출에 관한 비교연구

학위논문 (박사)-- 서울대학교 대학원 : 농경제사회학부 지역정보전공, 2013. 2. 최영찬.Abstracts A Comparative Study on Energy Use and Greenhouse Gas Emissions in Conventional and Organic Agriculture Kisong Lee Regional Information Department of Agricultural Economics and Rural Development Graduate School Seoul National University How to enhance the efficiency of energy use and to abate greenhouse gas emissions (GHGE) in agriculture has become very decisive in the mitigation of climate change. Organic farming has been recognized as the most reasonable alternative in agriculture to overcome this climate crisis. Studies on comparisons of energy use and greenhouse gas emissions (GHGE) between conventional and organic farming have been carried out vigorously in the previous decades. However, controversies exist over the problems in comparative studies on energy use and greenhouse gas emissions. Taking these contexts into consideration, the objectives of this study are (i) to identify the structural variables to determine the differences of energy efficiency (EE) and greenhouse gas emissions (GHGE) between conventional and organic farming systems through meta-analysis of previous studies(ii) to examine which input categories and farming practices cause the differences of energy efficiency (EE) and greenhouse gas emissions (GHGE) between conventional farming systems (CFS) and organic farming systems (OFS) by applying field studies on soybean production in Koreaand thereby, (iii) to explore alternative solutions to decrease environmental impacts in agriculture. First, the results of meta-analysis can be summarized as follows. 1. The results of the analysis obtained from 165 observations of 68 previous studies on the use of energy illustrate that 67.3% of their observations is positive in the organic superiority of EE - which means organic EE is higher than its counterpart. 2. In comparisons of EE ratio (%), - organic EE versus conventional EE -, the total mean value of EE ratio is 128.5%. This concludes that the EE of organic farming averages approximately 30% higher than that of conventional farming. 3. The results of the analysis on 195 observations of 66 previous studies on GHGE demonstrate that 67.7% of their observation is positive in the organic superiority of GHGE - which means organic GHGE is lower than its counterpart. The organic superiority of GHGE per ha basis is positive by 71.4%, and per ton basis is positive by 60.3%. 4. The GHGE ratio(%) shows 88.2%, which means that GHGE of organic farming is around 12% lower on the average than that of conventional farming. The GHGE ratio average per ha basis is 69.2%, which indicates that the GHGE of organic farming system (OFS) is considerably lower than that of conventional farming system (CFS), and the GHGE per ton basis is 96.5% on the average, which indicates that there is no difference between both systems per ton product unit. 5. As for the structural variables to determine the organic superiority of EE and GHGE, the duration of the data collection is estimated as the significantly influential variable to drive organic superiority of EE. The researchers selection on the energy coefficient values of input materials also appears as a very significant factor to affect the difference of EE between conventional farming systems (CFS) and organic farming systems (OFS). On the other hand, the variables of sample size, unit class, and farm product types appear to have a positive relationship with the organic superiority of GHGE. Second, the results of the field study on soybean production systems in Korea show considerable disparities with the European and American experiences. 1. The EE (0.98) of organic soybean farms is noticeably poorer than that of conventional farms (1.56). The energy consumption of OFS is higher than that of CFS, since the yields of OFS are apparently lower than that of CFS. 2. Seeds and mulch film in OFS and pesticides in CFS cause significant differences between both systems. Mulching and seeding used in OFS as well as weeding and spraying in CFS show significant variations between both systems. 3. Analysis of the input variables to drive the EE shows that fuel, fertilizers, mulch film, and labor are the influential input variables. As for the variables regarding farming practices to determine the EE, cultivation, mulching, threshing and grading are significantly related with EE. 4. The GHGE of organic soybean farms (1562.3 kg CO2eq/ha) is relatively lower than that of conventional farms (2003.2 kg CO2eq/ha). However, with respect to the product unit basis, the GHGE of organic soybean farms (1629.8kg CO2eq/ton) is inversely just a little higher than that of conventional farms (1473.1 kg CO2eq/ton). 5. In comparison of the GHGE by input categories between CFS and OFS, seeds and mulch film in OFS and pesticides in CFS led to significant differences between both systems. 6. Analysis of the input variables to drive the outcome of GHGE in both farm systems indicates fertilizers as a variable which is strongly influential. 7. Comparisons of LCIA (Life Cycle Impacts Assessment) between both soybean production systems show that 9 categories except ARD, EP and EU among 12 environmental impacts appear higher in CFS than in OFS. 8. In soybean production in Korea, fertilizers and manure are responsible for 37% of the total energy consumption in both systems. And they are the absolute contributors to GHGE which amount to 67.8% of total GHGE in both systems. This result indicates that although the use of synthetic fertilizers is reduced, the heavy use of animal manure can contribute greatly to the emission of nitrous oxide, which leads to the increase of GHGE. The substitution of manure in the place of synthetic fertilizers banned under organic agriculture regulations is not a recommendable alternative for organic farming. Therefore, reasonable strategies to mitigate climate change through energy consumption and GHGE reduction should be conducted not within, but beyond the scope of the nitrogen cycle. Finally, most previous studies did not present detailed statistical data except for the descriptive statistics of performance variables. This has led to limitation in explaining definitely the relationship of performance variables and structural variables. Therefore, for the progress of future EE and GHGE studies, presentation of more detailed data through the appropriate statistical analyses is required. In addition, more researches are needed in Asian countries including Korea, where studies on energy use and GHGE have not been pursued actively to date. Key Words : Energy use, Energy efficiency , Greenhouse gas emissions, Organic farming, Global warming. Climate change. Meta-analysis Student ID85514-806 E-mail : [email protected] of Contents I. Introduction 1 1.1 Problem Statement 11 1.2 Study Objectives 3 II. A Meta-Analysis of Structural Variables in Environmental Performances : Comparisons of Energy Use and Greenhouse Gas Emissions in Conventional and Organic Farming Systems 4 2.1 Introduction 4 2.2 Review of Literature 6 2.2.1 Indicators for Environmental Performance 7 2.2.2 Study Characteristics 17 2.2.3 Farm Characteristics 27 2.2.4 Selection of Energy Coefficients for EE Studies 33 2.2.5 Other Controversies on Comparative Studies of EE and GHGE 35 2.2.6 Meta-analyses on Environmental Performances 37 2.3 Methods and Data 38 2.3.1 Research Framework of Meta-analysis 40 2.3.2 Result Variables of Meta-analysis 41 2.3.3 Structural Variables and Hypotheses 43 2.3.4 Models of Statistical Analysis for Meta-analysis 50 2.3.5 Procedure of Meta-analysis 52 2.3.6 Data Collection 52 2.4 Results of Meta-analysis 54 2.4.1 General Characteristics of Structural Variables 56 2.4.2 Results of Meta-analysis on the Integrated EE & GHGE Studies 58 2.4.3 Results of Meta-analysis on the EE Studies 63 2.4.4 Results of Meta-analysis on the GHGE Studies 73 2.4.5 Relationship of Energy Coefficients and EE Ratio 82 2.5 Sub-conclusions and Implications 85 2.5.1 Structural Variables Influencing the Organic Superiority in EE and GHGE Studies 85 2.5.2 Implications for Future Research 90 III. An Empirical Field Study : Comparisons of Energy Use and Greenhouse Gas Emissions in Conventional and Organic Soybean Productions of Korea 95 3.1 Introduction 95 3.2 Review of Literature 96 3.3 Methods and Data 99 3.3.1 Research Framework of Field Study 99 3.3.2 Models of Statistical Analysis for Field Study 99 3.3.3 Calculation of EE and GHGE 101 3.3.4 Data Collection 107 3.4 Results of Energy Use 111 3.4.1 Energy Coefficients 111 3.4.2 General Characteristics of Farms and Energy Use 132 3.4.3 Comparison of Input Materials 133 3.4.4 Comparison of Energy Inputs 139 3.4.5 Comparison of Energy Use in Both Systems 146 3.4.6 Correlations of General Characteristics and EE 149 3.4.7 Comparison on the Characteristics of Energy Use 150 3.4.8 Driving Factors Determining the EE 156 3.5 Results of GHG Emissions 163 3.5.1 GHG Conversion Factors 163 3.5.2 General Characteristics of Farms and GHGE 181 3.5.3 Comparisons of GHGE between CFS and OFS 184 3.5.4 Relationship with Other Variables and the GHGE 200 3.6 Comprehensive Findings from the Results of Field Study 204 3.7 LCA in Field Study 206 3.7.1 Methods 206 3.7.2 LCIA (Life Cycle Impacts Assessment) 207 3.8 Implications of Field Study 214 IV. Implications and Measurements to Mitigate Climate Change 215 4.1 Environmental Performances and Food Security 215 4.2 Problem of Nitrogen-based Production Systems 217 4.3 EE and GHGE in Livestock 218 4.4 Food Consumption and Environmental Performances 220 4.5 New Trials for Carbon-oriented Farming 223 4.6 Priority of Financial Support 224 4.7 Expansion of Research on Environmental Impacts 225 V. Conclusions 227 5.1 Summary and Conclusions 227 5.2 Limitations and Recommendations 230 References 233 Appendix 251 국문초록 268Docto

매립 센서 네트워크에서 자기 공진을 이용한 무선 정보 및 전력 전송 방안

학위논문(박사) - 한국과학기술원 : 전기및전자공학과, 2013.8, [ vii, 92 p. ]Recently, for various purposes, sensor networks have been deployed in which the sensors are embedded in dense media including rock, soil, and water. For example, in ubiquitous home networks, sensors are embedded in the walls of building for convenience and aesthetic reasons. In addition, sensors are sometimes buried underground so that environmental conditions, the state of infrastructure, and other situations can be monitored. However, the embedding of sensors can present two main challenges to be considered. Sensors cannot be effective in communicating with other sensors through the dense media where they are embedded. And, any battery is unlikely to be practical as a power supply because it is difficult to replace. Therefore, a solution needs to be found to deal with these obstacles so that embedded sensors can operate reliably in practice. Therefore, in this thesis, we focus on the communication using magnetic induction for the transfer of information and wireless power transfer using magnetic resonance for supply of energy in embedded sensor networks. First, we attempt to maximize the capacity of magnetic induction communication in strongly and loosely coupled regions. In a strongly coupled region, we investigate frequency splitting, which disturbs the resonance of transmitter and receiver coils. We find a splitting coupling point, which is the value just before frequency splitting occurs, and propose an adaptive frequency-tracking scheme for finding an optimal frequency. The proposed scheme compensates for the degradation of capacity, so guarantees large capacity even at regions where frequency splitting occurs. Next, in a loosely coupled region, we derive an optimal quality factor for maximizing capacity in a two-coil system. As the distance between coils increases, strong resonance is needed to overcome the serious attenuation of signal strength. As a result, the optimal quality factor should be increased. In addition, we find an optimal quality facto...한국과학기술원 : 전기및전자공학과

OFDM 네트워크에서 셀 간 공평성을 개선하는 자원 할당 방안

학위논문(석사) - 한국과학기술원 : 전기및전자공학전공, 2009. 8., [ v, 37 p. ]As a wireless multimedia service requires the high spectral efficiency for guaranteeing its quality of service, the femto cell which has a small cell coverage is proposed as a promising system to achieve high data rate in future wireless communication network. However, the dynamic deployment of the femto cell makes communication system be more interference limited environment. Thus, inter-cell interference is the problem that we should solve to increase the spectral efficiency. Traditional papers focus on mainly sum capacity maximization by mitigating the inter-cell interference. However, the power allocation for the maximization of the sum capacity can cause an inter-cell unfairness problem due to the difference of traffic load in each cell. In this thesis, we focus on the guarantee of inter-cell fairness with minimizing the degradation of sum capacity. To solve this problem, we formulate an optimization problem to maximize the logarithmic sum capacity subject to a total power constraint per a base station. This optimization problem considers the mitigation of the inter-cell interference and the guarantee of the inter-cell fairness at the same time in interference limited multicell multiuser OFDM network. Based on analytic results, we propose an enhanced modified iterative water-filling algorithm which improves the inter-cell fairness compared to a modified iterative water-filling algorithm. Also, to apply the enhanced modified iterative water-filling algorithm in the communication environment where the fairness is the most important rather than the sum capacity, we propose an enhanced modified iterative water-filling algorithm with fairness enhancement. We verify the effectiveness of the proposed algorithms with respect to the fairness improvement and the little degradation in the sum capacity by intensive simulations. That is, our proposed algorithms provide efficient methods to solve the inter-cell unfairness problem in the interference limited communicat...한국과학기술원 : 전기및전자공학전공

APPARATUS AND METHOD FOR CONTROLLING POWER IN A LOCAL COMMUNICAION AND WIRELESS POWER TRANSMISSION SYSTEM

본 발명은 근거리 통신 및 무선 전력 전송 시스템에서 전력 제어 기술에 관한 것으로, 근거리 통신 및 무선 전력 전송을 동시에 수행하여 정보 및 전력의 전송을 가능하게 하며, 정보 전송을 위해 필요한 자기장 통신 용량을 보장하면서 무선 전력 전송 효율을 최대화하는 전력 제어를 수행하는 것을 특징으로 한다. 본 발명에 의하면, 매립 센서 네트워크에서 저용량 자기장 통신뿐만 아니라 대용량 자기장 통신까지도 함께 지원하면서 전력 전송도 동시에 가능하게 함으로써, 필요한 일정 양의 정보 전송을 가능하게 하며 동시에 매립 센서의 배터리 문제도 해결할 수 있다

FIELD COMMUNICATION SYSTEM AND METHOD

본 발명은 자기장 통신에서 품질 벡터의 변화를 통해 통신 용량을 증가시킬 수 있는 자기장 통신 시스템 및 방법에 관한 것이다. 이를 위하여 본 발명의 실시 예에 따른 자기장 통신 시스템은 자기장 통신을 수행하는 송수신부를 포함하며, 송수신부간의 결합 계수(coupling coefficient)를 계산하며, 계산된 결합 계수를 기반으로 산출된 최적 품질 팩터를 이용하여 자기장 통신을 수행하는 것을 특징으로 한다

Method for deciding multi hop relay path and the unit thereof

멀티 홉 릴레이 패스 결정방법 및 멀티 홉 릴레이 패스 결정유닛이 개시된다. 상기 멀티 홉 릴레이 패스 결정방법은 소스 단말과 목적 단말을 포함하는 네트워크에서 멀티 홉 릴레이 패스를 결정하는 방법에 있어서, 상기 소스 단말과 상기 목적 단말 사이의 복수 개의 경로가 탐색되는 단계, 탐색된 상기 경로들 각각에 포함된 링크별 여분 거리가 계산되는 단계, 및 계산된 여분 거리에 기초하여 결정되는 경로별 특성 값에 기초하여 상기 멀티 홉 릴레이 패스가 결정되는 단계를 포함한다

Tag set and method for reading data stored in the tag set

태그 집합 및 상기 태그 집합의 데이터 읽기 방법이 개시된다. 상기 태그 집합은 적어도 하나의 태그를 포함하는 적어도 하나의 태그 세트를 포함하며, 각각의 태그 세트에 포함되는 적어도 하나의 태그 각각은, 각각의 태그 세트별로 공통되는 값을 갖는 공통 ID부 및 상기 각각의 태그 세트에 포함된 태그별로 유니크한 값을 갖는 유니크 ID부를 포함한다

System and method for wireless power transmitting system capable to increase transmitting efficiency

전송 효율을 높일 수 있는 무선전력 전송시스템 및 그 방법이 개시된다. 상기 전송 효율을 높일 수 있는 무선전력 전송시스템은 자기 공진을 이용해 무선 전력 전송을 수행할 수 있는 복수의 송신장치들 및 상기 복수의 송신장치들 중 적어도 하나로부터 전력을 수신하는 수신장치를 포함하며, 상기 복수의 송신장치들 중 상기 수신장치로 전력을 전송하는 선택 송신장치는 상기 복수의 송신장치들 각각이 상기 수신장치에 대해 갖는 전력 전송효율에 기초하여 선택되는 것을 특징으로 한다