탄소 저장소로써의 단층분지: 한반도 동남부 지역에서의 토양 이산화탄소 배출 연구

학위논문(석사) -- 서울대학교대학원 : 자연과학대학 지구환경과학부, 2022. 8. 이현우.Carbon dioxide (CO2) is one of the main components of greenhouse gases. The carbon cycle and the CO2 sources and sinks are well studied, and fault systems are known to play significant roles in the natural C emission, as higher volatile fluxes were reported where permeable fracture zones exist. Most of the studies focused on the degassing through faults itself, while the role of sedimentary basins along the faults is rarely studied. In this study, we carried out a broad-scale CO2 flux survey in South Korea along with the Yangsan Fault System (YFS), including some fault-related natural springs and soil in the riverside. The CO2 flux was measured through the accumulation chamber method and associated with the graphical statistical analysis and isotope (13C-CO2) analysis. High CO2 flux (119.5 g m-2 d-1 ~ 77,699.5 g m-2 d-1) was observed in the fault-related carbonic springs, mainly located in the northern part of the YFS, while in the central part of the YFS, high soil CO2 fluxes (0.5 g m-2 d-1 ~ 1,240 g m-2 d-1) were observed along the Hyeongsan River with alluvium deposits. Carbon isotope compositions show that the deep mantle source contributes to the carbonic spring CO2 through the fault (-14.03 ‰ ~ -7.44 ‰), and soil CO2 originates from shallow biogenic sources deposited in fault-forming basins (-22.82 ‰ ~ -13.53 ‰). In addition, in a survey after a small earthquake at the survey site, we found changes in soil CO2 flux near the epicenter, that might be associated with the earthquake. A simple calculation of the total emission shows that a significant amount of CO2 is being released along the YSF and gives an implication that faults and fault-related basins could play important roles on the global carbon cycle as unknown carbon reservoir. This study along the YSF gave a unique opportunity to observe both massive tectonic degassing and biogenic CO2 emission, and investigate CO2 emission comprehensively with the roles of faults, fault-related sedimentary basins, and fluvial systems along with the fault system.이산화탄소는 주요 온실 기체 중 하나로 탄소 순환과 그 안에서의 이산화탄소의 이동은 많이 연구되어왔다. 그 중 자연적인 탄소 배출원과 관련해서는 단층이 중요한 역할을 한다고 잘 알려져있는데, 이는 단층대의 파쇄대를 따라서 이산화탄소를 비롯한 휘발성 성분 플럭스가 높게 관측되었기 때문이다. 그러나 대부분의 연구는 단층대를 통한 기체 유출 그 자체에만 초점을 맞춰왔고, 단층과 연관된 퇴적 분지의 역할은 그동안 주목받지 못했다. 이를 위해서 본 연구에서는 대한민국의 양산단층대를 따라 이산화탄소 플럭스 조사를 실시했다. 조사는 단층과 연관되었다고 알려진 자연 약수 및 단층대를 따라 분포하는 강변의 토양에서 실시했고, accumulation chamber method를 이용한 플럭스 측정과 graphical statistical analysis (GSA) 를 이용한 플럭스 분석 및 이산화탄소의 탄소 동위원소 분석을 수행하였다. 그 결과 주로 양산 단층대의 북부 지역에 위치한 자연 약수에서 높은 이산화탄소 플럭스 (119.5 g m-2 d-1 ~ 77,699.5 g m-2 d-1)가 관측되었고, 양산단층대 중부 지역에서는 형산강 근처 토양에서 높은 플럭스 (0.5 g m-2 d-1 ~ 1,240 g m-2 d-1)가 관측되었다. 또한 탄소동위원소 분석 결과는 자연 약수를 통해서는 맨틀 기원의 이산화탄소 (-14.03 ‰ ~ -7.44 ‰)가 방출되고, 강변의 토양을 통해서는 단층 분지에 퇴적된 천부 생물학적 기원의 이산화탄소 (-22.82 ‰ ~ -13.53 ‰)가 방출됨을 지시한다. 그리고 조사 지역에서 발생한 소규모 지진 이후 실시한 조사에서는 지진과 연관성이 있을 수 있는 토양 이산화탄소 플럭스의 변화가 간측되었다. 총 유출량 계산 결과는 상당량의 이산화탄소가 양산단층대에서 대기 중으로 유출되고 있음을 지시하고, 이는 탄소 순환에 있어서 단층과 단층분지가 탄소 저장소로써 중요한 역할을 할 수 있다는 사실을 함의한다. 양산단층대에서 수행된 본 연구를 통해서 대규모의 지질학적 그리고 생물학적 기원의 이산화탄소 유출을 모두 관측할 수 있었고, 단층과 퇴적분지, 그리고 하천 시스템과 관련해서 종합적으로 이산화탄소 유출을 분석할 수 있었다.List of tables ⅳ List of figures ⅴ I. Introduction 1 II. Regional Setting 4 III. Methods 8 III-1. Survey sites and plan 8 III-2. Measurement and sampling 11 IV. Results 13 IV-1. Spring flux 13 IV-2. Soil flux 16 IV-3. Isotope analysis 26 V. Discussion 27 V-1. CO2 sources 27 V-2. Faulting and CO2 flux 34 V-3. Earthquake and temporal changes in CO2 flux 39 V-4. Implications for the effect of faulting on the global carbon cycle 43 VI. Conclusions 47 Bibliography 48 국문초록 55 Supplementary material 57석

An Improved Analysis Method of Irreversible Demagnetization for a Single-Phase Line-Start Permanent Magnet Motor

This paper presents an effective analysis method of irreversible demagnetization for a line-start permanent magnet (PM) motor considering the magnetic field produced by secondary conductor bars. The magnetic field produced by the secondary conductor bars opposes the variation of the magnetic field caused by the primary part, and these result in the reduced magnetic field acting on the PM. By using finite element analysis in the transient magnetic field, currents in the primary and secondary conductors are estimated and used for demagnetization analysis of the magneto-static field. Therefore, conditions closer to actual situations can be achieved. Both the general demagnetization analysis method, using only primary currents, and presented analysis method are compared and the results are verified by experiments. General demagnetization analysis leads to over-estimation of the magnetic field acting on the PM, and results in excessive PM usage.This work was supported by the Ministry of Trade, Industry, and Energy, Korea Institute for Advancement of Technology through the Encouragement Program for The Industries of Economic Cooperation Region

유기 전계효과 트랜지스터에서 효율적인 전하 주입 및 전하 이동을 위한 저분자의 자기 조립에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 화학부, 2011.2. 이성훈.Docto

Characteristics Analysis of SPMSM Using 2-D Finite-Element Analysis Considering Axial Leakage Flux

In this paper, the characteristics analysis of the surface-mounted permanent-magnet synchronous motor is carried out using the method of reflecting the axial leakage magnetic flux into the 2-D finite-element analysis (2-D FEA), and the result is discussed. For the method of projecting the axial leakage flux on the 2-D plane, the permeance coefficient was introduced. By using the proposed method, the parameters such as d- and q-axes inductance and linkage flux for d- and q-axes equivalent circuit analysis were calculated, and the characteristics analysis was performed. In order to verify the effectiveness of the proposed 2-D FEA, a speed versus torque experiment was performed and compared with the analysis results.This work was supported by the Advanced Brake Engineering Team, Hyundai Mobis, Yongin, South Korea

축소모형 실험방법을 이용한 경골 목조 전단벽의 성능 평가

Thesis (master`s)--서울대학교 대학원 :임산공학과,1999.Maste

Torque Improvement of Wound Field Synchronous Motor for Electric Vehicle by PM-assist

In order to improve the performance of the wound field synchronous motor (WFSM), the permanent magnet assist (PM-assist) is investigated in this paper. The effect of the PM-assist is dependent on the inserted position of the PMs. Thus, four models whose PMs are inserted at each different position are suggested. Then, the most effective position of the PM is decided by the mean torque per employed amount of the PM. By inserting the PMs into the decided position of a WFSM designed for a small electric vehicle traction, the PM-assisted WFSM is designed. By comparing the torque and the efficiency of the original WFSM and the PM-assisted WFSM, the effectiveness of the PM-assist is figured out. Finally, the validity of this research is verified by the experiment using the manufactured WFSM.This work was supported by Korea Electrotechnology Research Institute (KERI) Primary Research Program through the National Research Council of Science and Technology (NST) funded by the Ministry of Science and ICT (MSIT) (No. 18-12-N0101-27). (Corresponding author: Jung-Pyo Hong.

매입형 영구자석 전동기에서 무부하시 공극 자속밀도 분포에 대한 Slot-Opening Effect를 고려한 보조 모델

This paper proposes an effective assistant model for considering the stator slot-opening effect on air gap flux density distribution in conventional interior-type permanent magnet (IPM) motor. Different from the conventional slot-opening effect analysis in surface-type PM (SPM) motor, a composite effect of slot-opening uniquely existing in IPM motor, which additionally causes enhancement of air gap flux density due to magnet flux path distortion in iron core between the buried PM and rotor surface. This phenomenon is represented by a proposed assistant model, which simply deals with this additional effect by modifying magnetic pole-arc using an effective method. The validity of this proposed analytical model is applied to predict the air gap flux density distribution in an IPM motor model and confirmed by finite element method (FEM)

Finite-Element Analysis of Local Flux Density Variation Considering PWM Current Harmonics

Large amounts of harmonics are contained in the current as the motor is driven by pulse width modulation (PWM). Significant amounts of computing time are required to compute local flux density variation considering such current harmonics. Since the amplitudes of higher harmonics are significantly smaller than that of fundamental harmonic, flux density variations due to the higher harmonics are small, and the relationship between the field strength and flux density can be assumed to be linear. When the operating point of each element is known, flux density variations for the higher harmonics can be analyzed by linear finite-element analysis (FEA). This paper suggests a method to calculate flux density variations in the iron core while taking into considering PWM current harmonics. First, the operating point solution is obtained by nonlinear FEA, second each element is linearized. Then, the flux density for the PWM current is obtained through linear FEA. Finally, the obtained results are presented and compared with nonlinear FEA results for verification.This work was supported by the Ministry of Science and ICT, South Korea, through the Information Technology Research Center support program (IITP-2017-2012-0-00628) supervised by the Institute for Information and communications Technology Promotion

Design of High Efficiency Wound Field Synchronous Machine with Winding Connection Change Method

In this paper, a design method for a wound field synchronous motor (WFSM) employing the dual stator winding and the winding connection change circuit is proposed. Through the design method, the WFSM can be operated as two different modes, and each mode is determined by the connection between the stator windings U, V, W and X, Y, Z. By applying the proposed method to the conventional WFSM, the operation mode of the motor is changed at a certain speed. The speed for the mode change is determined to maximize the efficiency of the machine. As a result, through the mode change, the line to line induced voltage, current phase angle, and phase resistance are decreased. In addition, the demand field current is also reduced to achieve the required torque due to the salient pole characteristics of WFSM. Consequently, the efficiency of the WFSM is increased due to the mode change. Finally, the effect of the proposed method and the validity of the simulation results are verified by the load test

Smoking habits of coal workers' pheumoconiosis patients: their relationship to the findings of chest radiographs

보건학과/석사[한글] 본 연구는 탄광부 진폐증자의 흡연 실태 및 흉부방사선 사진 소견상 진폐증의 진행정도와 흡연 습관의 관련성을 알아보고자 하였다. 조사 대상은 1986넌 5월부터 7월 사이에 진폐증 환자 전문 요양기관인 D 병원에 내원하여 진폐 정밀진단을 받은 사람 중 흉부방사선사진 소견상 진폐 의증 이상으로 판정된 남자 460 명이었다. 면접조사를 통하여 얻은 흉언 습관에 관한 자료와 방사선과 전문의가 판독한 자료를 이용하여 다음의 연구 결과를 얻었다. 1. 탄광부 진폐증자의 흡연율은 72 4% 였으며 과거흡연자는 17.0%, 비흡연자는 10.7%로 흡연 경험자는 89.3%였으며 흡연 경험자의 흡연 중단율은 19.O%였다. 2. 과거흡연자의 금연 전 흡연량은 18.0 개피로 흡연자의 흡연량 14.5개피와 유의한 차이가 있었다(p<0.05). 3. 탄광부 진폐증자의 흉부방사선 사진 소견상 소음영의 크기는 흡연경험자의 흡연 중단율 및 흡연량과 유의한 상관 관계가 있었으려 음영의 크기가 클수록 흡연 중단율은 증가하였고 흡연량 감소하였다(흡연 중단율: beta= 0.19, 흡연량:beta=0.14). Smoking Habits of Coal Workers' Pneumoconiosis Patient: Their Relationship to the Findings of Chest Radiographs Jeong Pyo Hong Graduate School of Health Science and Management, Yonsei University (Directed by Professor Young Hahn Moon, M.D.) This study was performend to investigate smoking habits of coal workers' pneumoconiosis (CWP) patients, and the relationships between smoking habits and types of radiographical findings of CWP patients. With detailed examination, 460 patients of profusion 0/1 or more advanced were selected from May to July in 1986. They were present or retired coal miners. Data of smoking habits were obtained by interview, and the findings of chest radiographs were evaluated by one radiologist. The results were as follows: 1. The percentage distribution of nonsmokers, smokers and ex-smokers in CWP patients by smoking habits were 10.7, 72.4, and 17.0 respectively. 2. There were significant difference in the number of cigarettes smoked per day between smokers and ex-smokers (smokers : 14.5±6.6, ex-smokers : 18.0±12.1 ; p<0.05). 3. The opacity sizes were significantly correlated with smoking quit rate and with the number of cigarettes smoked per day (smoking quit rate : beta=0.19 ; p<0.05, the number of cigarettes smoked per day : beta = 0.14 : p<0.01). [영문] This study was performend to investigate smoking habits of coal workers' pneumoconiosis (CWP) patients, and the relationships between smoking habits and types of radiographical findings of CWP patients. With detailed examination, 460 patients of profusion 0/1 or more advanced were selected from May to July in 1986. They were present or retired coal miners. Data of smoking habits were obtained by interview, and the findings of chest radiographs were evaluated by one radiologist. The results were as follows: 1. The percentage distribution of nonsmokers, smokers and ex-smokers in CWP patients by smoking habits were 10.7, 72.4, and 17.0 respectively. 2. There were significant difference in the number of cigarettes smoked per day between smokers and ex-smokers (smokers : 14.5±6.6, ex-smokers : 18.0±12.1 ; p<0.05). 3. The opacity sizes were significantly correlated with smoking quit rate and with the number of cigarettes smoked per day (smoking quit rate : beta=0.19 ; p<0.05, the number of cigarettes smoked per day : beta = 0.14 : p<0.01).restrictio