Application of Linear Regression, Random Forest, and Artificial Neural Networks

학위논문(석사) -- 서울대학교대학원 : 공과대학 에너지시스템공학부, 2023. 2. 정은혜.Acid mine drainage (AMD) is a global problem due to the high content of heavy metals and low pH and needs to be monitored and managed by reclamation or treatment systems. The performance of AMD treatment systems is difficult to predict due to the numerous factors associated. Empirical and geochemical models have been developed to predict AMD treatment. Machine learning-based access can be an alternative when the amount of data and time required to build models are limited. In this study, random forest (RF) and artificial neural network (ANN) model were constructed for predicting the Fe(Ⅱ) and Mn removal efficiencies of passive systems in 9 abandoned coal mines and compared to the performance of the multiple linear regression (MLR) model. Among the three models, the RF model showed the best performance in both predicting the Fe(Ⅱ) and Mn removal efficiency. According to the sensitivity analysis, the pH of the inflow water, the Fe(Ⅱ) concentration of the inflow water, and the alkalinity were the most important variables for predicting the Fe(Ⅱ) removal efficiency. The alkalinity of the inflow water and the pH of the inflow water were important variables to predict Mn removal efficiency.산성광산배수(AMD)는 높은 중금속과 낮은 pH로 인해 세계적인 문제로 대두되었으며 지속적인 모니터링과 처리시설을 이용한 관리를 필요로 한다. 산성광산배수의 처리는 pH, 금속의 농도 등 연관된 수많은 요인으로 인해 예측에 어려움이 있다. 광산 배수 내 중금속의 제거를 예측하기 위한 경험적 및 지구화학적 모델이 개발되어왔으나 모델을 구축하는 데 많은 시간이 소요되고 충분한 양의 데이터를 필요로 하기 때문에, 제한된 정보로도 예측이 가능한 머신 러닝 기반 모델을 구축할 필요성이 존재한다. 본 연구에서는 한국의 9개 폐탄광에 대하여 수동적 처리 시스템의 Fe(Ⅱ) 및 Mn 제거 효율을 예측하기 위해 RF 및 ANN 모델을 구축하였고, 이를 MLR 모델의 성능과 비교하였다. 이중, RF 모델이 Fe(Ⅱ) 제거 Mn 제거 효율 예측 모두에서 가장 우수한 성능을 보였다. 민감도 분석 결과, Fe(Ⅱ) 제거 효율을 예측하는 데 가장 중요한 변수 세 가지는 순서대로 유입수의 pH, 유입수의 Fe(Ⅱ) 농도 및 알칼리도였다. Mn 제거 효율 예측을 위한 세 가지 중요한 변수는 순서대로 유입수의 알칼리도, 유입수의 pH, 유입수의 Mn 농도로 분석되었다.Chapter 1. Introduction 1 1.1. Research Background 1 1.2. Research Objective 6 Chapter 2. Background Theory 7 2.1. Passive Treatment Systems 7 2.1.1. Oxidation Ponds (OPs) 8 2.1.2. Aerobic Wetlands (AeWs) 9 2.1.3. Successive Alkalinity-Producing Systems (SAPS) 10 2.2. Predictive Models 11 2.2.1. Multiple Linear Regression (MLR) 11 2.2.2. Random Forest (RF) 13 2.2.3. Artificial Neural Networks (ANN) 14 Chapter 3. Methodology 23 3.1. Data Description 23 3.2. Data Sampling 27 3.3. Setting Variables 28 3.4. Correlation Analysis 30 3.5. Data Split 31 3.6. Model Construction 32 3.6.1. Multiple Linear Regression 32 3.6.2. Random Forest 33 3.6.3. Artificial Neural Networks 35 3.7. Model Evaluation 36 3.8. Variable Importance 38 3.8.1. Random Forest 38 3.8.2. Artificial Neural Network 40 Chapter 4. Result 42 4.1. Data Summary 42 4.2. Correlation Analysis 44 4.2.1. Variables of Fe(Ⅱ) Dataset 44 4.2.2. Variables of Mn Dataset 46 4.3. Optimization of MLR model 48 4.4. Comparison of Removal Efficiency Prediction 51 4.4.1. Train Dataset Prediction 51 4.4.2. Test Dataset Prediction 55 4.4.2.1. Prediction of Fe(Ⅱ) Removal Efficiency 55 4.4.2.2. Prediction of Mn Removal Efficiency 59 4.5. Variable Importance 63 4.5.1. Variable Importance in FRE Prediction 63 4.5.2. Variable Importance in MRE Prediction 65 Chapter 5. Discussion 67 Chapter 6. Conclusion 70 References 71 Abstract in Korean 84석

콘크리트 Split Hopkinson Pressure Bar 실험절차의 표준화

학위논문(박사) -- 서울대학교대학원 : 공과대학 건설환경공학부, 2023. 2. 조재열.Recently, extreme events such as the explosion of plants, collision of vehicles, rockfall, and impact of aircraft or missiles have frequently occurred. Accordingly, the necessity of research on extreme loadings such as impact-resistant performance evaluation of structures subjected to extreme loading has increased for the safety of social infrastructures. Concrete, which is the most widely used material for the construction of social infrastructures, has rate-dependent properties. The compressive strength of concrete is enhanced as the strain rate increases due to the strain-rate effect and shows different behavior compared to that under general static loadings. Therefore, it is necessary to investigate the dynamic material properties of the concrete for accurate evaluation and economical design of the structures under extreme loadings. In particular, the dynamic compressive strength of concrete can be obtained through various dynamic material tests and the split Hopkinson pressure bar (SHPB) test has been chiefly performed. However, the main limitation of the concrete SHPB test is the absence of the standard test method. Since concrete is non-homogeneous material consisting of various components with different particle sizes such as coarse and fine aggregates, the dispersion of the test results is more severe than in homogenous materials such as metals. In addition, the frictional effect in the SHPB test might result in the overestimation of the dynamic compressive strength due to the strain-rate effect. For this reason, it is difficult to consistently and accurately evaluate the dynamic compressive strength through the SHPB test without a standardized guideline. Therefore, a standardized test method should be established covering from the specimen preparation to acquisition process of test results to obtain accurate and consistent dynamic compressive strength of concrete through SHPB tests. The main objective of this study is to develop an SHPB test procedure to improve the consistency of the dynamic compressive strength evaluation. For this objective, the contents which should be included in the SHPB test method were drawn. Among the contents, three main subjects were selected; specimen dimension, lubrication method, and loading condition. To suggest proper guidelines for each subject, previous experimental and numerical studies were reviewed and a series of experimental and numerical works were conducted. At first, SHPB tests were performed for 240 specimens to suggest a guideline to decide the concrete specimen dimension. To this end, maximum coarse aggregate sizes and specimen dimensions were selected as the main variables. In particular, the maximum coarse aggregate sizes used in the actual construction site were included. The size of coarse aggregate may affect the dispersion of test results because concrete is non-homogeneous material. Therefore, the effect of maximum coarse aggregate size on the dispersion of the test results was investigated and the dynamic increase factor (DIF) for each size of maximum coarse aggregate through the SHPB test was obtained and compared. Based on the test results, a guideline for the determination of the specimen dimension was suggested to secure consistent test results: (1) specimen dimension should be at least three times Gmax, and (2) actual Gmax should be used in the concrete SHPB test. Secondly, numerical and experimental studies were carried out to propose an appropriate lubricating technique. In the concrete SHPB test, the friction on the interfaces between specimen and bars induces confining effect. This effect additionally enhances the dynamic compressive strength in the increased strength by the strain-rate effect, which results in the overestimation of the dynamic compressive strength. Accordingly, an adequate lubricating technique to minimize the frictional effect is essential for the accurate evaluation of the dynamic compressive strength of concrete. For necessity, this study conducted concrete SHPB tests for 52 specimens with the main variables of lubricant type and amount of lubricant to suggest a proper lubrication method. Then the proposed method was thoroughly verified through a follow-up SHPB test for 75 concrete specimens with various specimen dimensions. Based on the tests, the lubrication method was suggested to eliminate the frictional effect in the concrete SHPB test: the specimens should be lubricated with the amount of 12 mg/cm2 or more with one of the lubricants, high vacuum grease, petroleum jelly, or Teflon. Lastly, the study on the determination method of the incident stress wave to secure valid test results was performed. In order to obtain valid results, the dynamic stress equilibrium of the specimen should be achieved during the SHPB test. The dynamic stress equilibrium of the specimen is influenced by the specimen properties and the incident stress waves of the test. Therefore, an available range of the incident stress wave should be defined considering the specimen properties. This study proposed the range of the incident wave rate using the previous concrete SHPB test results which makes the specimen satisfy the dynamic stress equilibrium considering the specimen properties. The suggested range was verified through the concrete SHPB test for 184 specimens with various properties such as the dimension and the static compressive strength. Then the suggested range was modified using additional test results obtained in this study. Finally, a test procedure for the concrete SHPB test to obtain consistent results was developed based on each experimental result conducted in this study. In addition, the applicability of the developed test method was verified. The developed test method of the concrete SHPB test can provide a high-quality database of concrete dynamic material properties under extreme loadings. Furthermore, the suggested test procedure can be used as a standard test method for the concrete SHPB test and improve the reliability of the impact-resistant performance evaluation of materials.최근 플랜트 폭발, 차량 및 선박 충돌, 낙석, 그리고 항공기 또는 미사일 충돌과 같은 극한상황의 발생 빈도가 높아지고 있다. 이에 따라 사회기반시설의 안전을 위하여 극한하중 하 구조물의 내충격 성능평가 등 극한하중과 관련된 연구의 필요성 또한 증대되고 있다. 특히, 사회기반시설의 필수 재료인 콘크리트는 변형률 속도 의존 특성을 지닌 재료이다. 콘크리트 압축강도는 변형률 속도 효과에 의하여 변형률 속도가 높아짐에 따라 증진되며, 일상적인 범주의 하중을 받는 경우와 다른 거동을 보인다. 따라서, 극한하중을 받는 구조물의 정확한 성능 평가와 경제적인 설계를 위해서는 콘크리트의 동적압축특성의 파악이 필수적이다. 특히 콘크리트의 동적압축강도는 다양한 동적재료실험을 통해 획득할 수 있으며, split Hopkinson pressure bar (SHPB) 실험이 주로 수행되고 있다. 그러나 콘크리트 SHPB 실험의 가장 큰 한계점은 표준실험절차가 정립되지 않았다는 것이다. 콘크리트는 굵은골재 및 잔골재 같이 입자의 크기가 다른 성분들로 이루어진 비균질 재료로, 금속과 같은 균질 재료에 비해 상대적으로 실험결과의 분산성이 크게 나타난다. 또한 SHPB 실험에서는 마찰효과에 의해 변형률 속도 효과에 의해 증진된 동적압축강도를 과대평가할 수 있다. 그렇기 때문에 표준화된 SHPB 실험절차가 없다면 일관되고 정확하게 동적압축강도를 평가하기 어렵다. 따라서 SHPB 실험을 통해 정확하고 일관된 콘크리트의 동적압축강도를 획득하기 위해서는 시편 제작부터 실험결과의 획득까지 표준화된 실험방법의 개발이 필요하다. 이 연구의 주 목적은 콘크리트 동적압축강도 평가의 일관성을 향상시키기 위한 SHPB 실험절차 정립이다. 이를 위해 SHPB 실험절차에 포함되어야 할 항목들을 선정하였다. 여러 항목들 중 시편 치수, 윤활 방법, 그리고 하중 조건의 세 가지 주요 주제를 선정하였다. 각 주제에 대해 적절한 가이드라인 제시를 위해 선행 실험 및 수치해석 연구들을 분석하였으며, 일련의 실험 및 수치해석 연구를 수행하였다. 첫번째로, 콘크리트 시편 치수를 결정하기 위한 가이드라인 제시를 위해 240개의 시편에 대해 SHPB 실험을 수행하였다. 굵은골재 최대치수와 시편 치수를 주요 변수로 설정하였으며, 특히 실제 건설 현장에서 사용되는 크기의 굵은골재를 포함하였다. 콘크리트는 비균질성 재료이므로 굵은골재의 크기가 실험결과의 분산성에 영향을 미칠 수 있다. 따라서 굵은골재 최대치수가 실험결과의 분산성에 미치는 영향을 확인하였으며, 각각의 굵은골재 크기에 따른 동적증가계수(DIF)를 획득하고 비교하였다. 실험결과를 바탕으로 일관된 실험결과의 확보를 위한 콘크리트 SHPB 실험 시편 치수 결정 가이드라인을 다음과 같이 제시하였다: (1) 시편 치수는 굵은골재 최대치수의 최소 3배여야 하며 (2) 실제로 사용되는 굵은골재를 콘크리트 SHPB 실험에 사용해야 한다. 다음으로, 적절한 윤활방법을 제시하기 위한 수치해석 및 실험연구를 수행하였다. 콘크리트 SHPB 실험에서는 장비와 시편 사이의 마찰이 구속효과를 야기한다. 이러한 마찰효과는 변형률 속도 효과에 의한 압축강도 증진 외에 추가적으로 압축강도를 증진시키므로 동적압축강도의 과대평가를 유발한다. 따라서 정확한 동적압축강도 평가를 위해SHPB 실험 시 장비와 시편 사이의 마찰을 최소화할 수 있는 적절한 윤활방법이 필요하다. 이 연구에서는 적절한 윤활 방법 제시를 위해 윤활제 종류와 윤활제 도포량을 주요 변수로 설정하여 52회의 콘크리트 SHPB 실험을 수행하였다. 그리고 다양한 치수를 갖는 75개의 콘크리트 시편에 대한 후속 SHPB 실험을 수행하여 제시한 윤활방법을 검증하였다. 실험결과들을 바탕으로 콘크리트 SHPB 실험에서 마찰효과를 제거하기 위한 윤활방법을 다음과 같이 제시하였다: 시편은 고진공 그리스, 페트롤륨 젤리, 또는 테플론 윤활제를 12 mg/cm2 이상 도포하여야 한다. 마지막으로, 유효한 실험결과를 확보할 수 있도록 하는 입사응력파 결정방법 제시를 위한 연구를 수행하였다. 콘크리트 SHPB실험 시 유효한 실험결과를 획득하기 위해서는 시편의 동적응력평형이 만족되어야 한다. 시편의 동적응력평형은 시편의 특성 및 SHPB 실험의 중인 입사응력파의 영향을 받는다. 따라서 시편의 특성을 고려하였을 때 사용 가능한 입사응력파 범위가 정의되어야 한다. 이 연구에서는 선행된 콘크리트 SHPB 실험결과들을 바탕으로 시편이 동적응력평형을 만족할 수 있도록 하는 시편 특성을 고려한 입사응력파 변화율 범위를 제시하였다. 제시한 입사응력파 변화율의 범위는 시편 치수 및 정적압축강도와 같이 다양한 시편 특성을 지닌 184개의 시편에 대한 콘크리트 SHPB 실험을 통해 검증되었다. 또한 추가된 실험결과를 활용하여 제시한 범위를 수정하였다. 최종적으로 각각의 연구결과들을 바탕으로 콘크리트 동적압축강도를 일관되게 평가할 수 있도록 하는 SHPB 실험절차를 개발하였다. 또한 개발한 실험절차서의 적용성을 검증하였다. 이와 같이 개발한 콘크리트 SHPB 실험절차는 극한하중 하 콘크리트의 동적재료특성 획득과 관련하여 양질의 데이터베이스를 구축할 수 있게 한다. 또한 이 연구를 통해 개발한 콘크리트 SHPB 실험절차는 표준실험절차로 활용될 수 있으며 구조물 및 재료의 극한성능평가의 신뢰도를 향상시킬 수 있다.1. Introduction 1 1.1. Research background 1 1.2. Research objective and scope 6 1.3. Outline 7 2. Literature Review 8 2.1. Principle of split Hopkinson pressure bar test 8 2.2. Previous studies on concrete SHPB test 13 2.2.1. Specimen dimension 13 2.2.1.1. Hao and Hao (2011) 16 2.2.1.2. Chen et al. (2013) 17 2.2.1.3. Hao et al. (2013a) 19 2.2.1.4. Kim et al. (2019) 21 2.2.2. Lubrication method 23 2.2.2.1. Li and Meng (2003) 25 2.2.2.2. Li et al. (2009) 26 2.2.2.3. Kim et al. (2010) 26 2.2.2.4. Hao et al. (2013a) 27 2.2.2.5. Hao et al. (2013b) 28 2.2.2.6. Liu et al. (2018) 30 2.2.3. Loading condition 32 2.2.3.1. Lu and Li (2010) 34 2.2.3.2. Heard et al. (2014) 37 2.2.3.3. Shemirani et al. (2016) 38 2.2.3.4. Xu and Wille (2016) 40 2.2.3.5. Hassan and Wille (2017) 43 2.3. Concluding remarks 45 3. Effect of Maximum Coarse Aggregate Size in Concrete SHPB Test 49 3.1. SHPB test program 49 3.1.1. Test variables 49 3.1.2. Specimen preparation 51 3.1.3. Test procedure 53 3.1.4. Data acquisition and processing 55 3.1.5. Test results 58 3.1.5.1. Dynamic stress equilibrium 58 3.1.5.2. Reproducibility of test 61 3.1.5.3. Apparent DIF 64 3.2. Effect of maximum coarse aggregate size 66 3.2.1. Dispersion of test results 66 3.2.2. Pure rate DIF 69 3.3. Concluding remarks 72 4. Effect of Friction in Concrete SHPB Test 74 4.1. SHPB test program for suggestion of lubrication method 74 4.1.1. Test variables 74 4.1.2. Specimen preparation 76 4.1.3. Test procedure 77 4.1.4. Data acquisition and processing 79 4.1.5. Test results 80 4.1.5.1. Dynamic stress equilibrium 80 4.1.5.2. Apparent DIF 82 4.1.6. Effect of friction along lubrication condition 83 4.1.6.1. Apparent DIF according to the amount of lubricant 83 4.1.6.2. Crack patterns according to lubrication 86 4.2. SHPB test program for verification of lubrication method 89 4.2.1. Test variables 89 4.2.2. Specimen preparation 92 4.2.3. Test procedure 93 4.2.4. Data acquisition and processing 94 4.2.5. Test results 96 4.2.5.1. Dynamic stress equilibrium 96 4.2.5.2. Apparent DIF 97 4.2.6. Verification of suggested lubrication method 98 4.2.6.1. Apparent DIF according to lubrication 98 4.2.6.2. Crack patterns according to lubrication 100 4.3. Effect of friction 102 4.3.1. Pure rate DIF 102 4.3.2. Validation of lubrication method 103 4.3.2.1. Analysis details 103 4.3.2.2. Analysis results 107 4.4. Concluding remarks 109 5. Effect of Incident Wave Rate in Concrete SHPB Test 112 5.1. Suggestion of desirable incident wave rate 112 5.1.1. Characteristic of incident stress wave 112 5.1.2. Available incident wave rate 114 5.2. SHPB test program to verify incident wave rate 124 5.2.1. Test variables 124 5.2.2. Specimen preparation 128 5.2.3. Test procedure 129 5.2.4. Data acquisition and processing 131 5.2.5. Test results and discussions 133 5.2.5.1. Dynamic stress equilibrium according to incident wave rate 133 5.2.5.2. Modification of the incident wave rate range 140 5.3. Concluding remarks 143 6. Establishment of Test Method for Concrete Compressive SHPB Test 145 6.1. Establishment of test method 145 6.1.1. Specimen preparation 145 6.1.1.1. Determination of the specimen dimension 145 6.1.1.2. Measurement of specimen length and error of perpendicularity 146 6.1.2. Lubrication method 147 6.1.3. Loading condition 147 6.1.4. Data acquisition and processing 149 6.1.4.1. Data acquisition 149 6.1.4.2. Data processing 150 6.1.5. Report 150 6.2. Examples of test results 151 6.2.1. Apparent DIF 151 6.2.2. Pure rate DIF 154 6.3. Concluding remarks 157 7. Conclusions 159 7.1. Summary and major findings of this study 159 7.2. Recommendations for further studies 162 Reference 165 Appendix A 174 Appendix B 197 Appendix C 246 Appendix D 290 국문초록 329박

축산업의 유전자공학 기반 고도화 기술: 우수한 소 형질 개량을 위한 다양한 전략

학위논문(박사) -- 서울대학교대학원 : 수의과대학 수의학과, 2023. 2. 장구.This study aimed to produce specific gene mutated (PRNP and MSTN) cattle through cytoplasmic microinjection based on the CRISPR/Cas9 system and to verify that mutant traits are transferred to the next generation by germline transmission. First, to produce PRNP-mutated cattle, piggyBac transposon and CRISPR/Cas9 were used. A transposon vector with Cas9, GFP, and sgRNA for PRNP was applied to bovine somatic cells and embryos. Cas9 and sgRNA were inserted into the bovine genome and PRNP mutation was induced. Then, GFP-expressing blastocysts were selected and transferred into 18 surrogates. Finally, 7 calves were successfully born. Among them, 6 calves (#P1, #P3, #P4, #P5, #P6, and #P7) showed vector insertion (Cas9, sgRNA for PRNP), and their mutation rates were 4.1%, 48.3%, 0.2%, 0.0%, 99.6%, and 94.4%, respectively. However, GFP expression and Cas9 activity were observed in only 4 calves (#P1, #P3, #P4, and #P7). To verify germline transmission, #P3 and #P7 germ cells were cultured in vitro, and PRNP mutation was detected in their blastocysts. As further gene editing, GGTA1 mutation was introduced into the embryos using electroporation. Using germ cells (#P3 and #P7), 7 F1 calves became pregnant. In F1 cattle, the gene of interest in All-in-one DNAs (Cas9, GFP, and sgRNA for PRNP) was identified, and PRNP mutation was detected. In addition, to study PRNP function in detail, conditional PRNP-mutant cattle were produced based on the Cre/loxP system. After Cre treatment, the somatic cells of the cattle expressed Cas9, but showed no PRNP mutation. As a result of germline transmission of the conditional PRNP male cattle, transgene integration and GFP expression were observed in blastocysts fertilized with semen. Second, to generate MSTN-mutant cattle, cytoplasmic microinjection based on the CRISPR/Cas9 system was used. Through this, MSTN-mutant calves were successfully produced. The MSTN mutation pattern was the same with 12-base pair deletion, and, in case of calf #17, enhanced muscle growth was observed. Furthermore, blood analysis results showed no abnormalities in the MSTN-mutant cattle. Next, whether MSTN mutation was transferred to the next generation (F1) was confirmed. For this purpose, oocytes and semen were collected after sexual maturation of the MSTN cattle (#6 and #17), and embryos produced by in vitro fertilization were analyzed. In addition, the embryos were subjected to additional gene (PRNP) editing using electroporation. Embryos produced by in vitro fertilization with the MSTN male and female cattle were transferred to a surrogate, and 1 calf was successfully born. MSTN heterozygous mutation was observed on sequencing of the F1 calf, which had no health issues. As a further experiment, using electroporation, the additional gene-edited embryos fertilized with the MSTN male sperm showed high PRNP mutation rate (86.2 ± 3.4%). In conclusion, this study is the first to produce PRNP-mutant cattle using transposon and the CRISPR/Cas9 system and MSTN-mutant cattle without exogenous gene integration. In addition, germline transmission was confirmed. The CRISPR/Cas9 system can be used to produce specific gene-mutant cattle with high efficiency and can be applied in various fields, such as livestock industry and veterinary medicine.본 연구의 목적은 CRISPR/Cas9 이용하여 특정 유전자(PRNP, MSTN)을 타겟팅하여 돌연변이가 유도된 형질전환 소를 생산하는 것과 그 돌연변이가 다음 세대로 정상적으로 생식선 전이가 일어나는 것을 확인하는 것이다. 첫번째 PRNP 돌연변이 소를 생산하기 위해서 microinjection과 Piggybac 트랜스포존을 이용하여, PRNP 유전자에 돌연변이를 유도하였다. Cas9, GFP, PRNP 가이드 RNA가 포함된 트랜스포존 벡터가 소의 체세포와 수정란의 유전체에 정상적으로 삽입이 되고, PRNP 유전자에 돌연변이가 발생되는 것을 확인되었다. GFP 발현하는 배반포를 선별하여 18마리의 수란우에 이식하여 7마리의 송아지를 생산하였다. 생산된 7마리 중에서 4마리에서 성공적으로 PRNP 돌연변이를 보여주었다. 생식선 전이를 확인하기 위해서 #P3, #P7 소의 정상적인 성 성숙 이후 생식세포를 이용하였다. 이들의 생식세포를 이용하여 생성된 배반포에서 PRNP 돌연변이를 확인되었고, 수정란 이식을 통해서 성공적으로 F1 송아지에서 PRNP 돌연변이가 정상적으로 생식선 전이가 이루어지는 것을 관찰하였다. PRNP 유전자를 구체적으로 분석하기 위해서, Cre/loxP 시스템을 기반으로 하여, conditional PRNP 돌연변이 소를 생산하였다. 하지만, F0의 체세포에서 Cre 단백질 처리이후 Cas9 단백질 발현은 정상적으로 이루어 졌지만, PRNP 유전자 돌연변이는 발생되지 않았다. 하지만, conditional PRNP 돌연변이 수컷에서 정상적인 생식전전이를 수정란 체외배양으로 생산된 배반포에서 관찰이 되었다. 두번째 연구로서, 외래 유전자 삽입이 없는 MSTN 돌연변이 소를 생산하기 위해서 Cas9 mRNA와 sgRNA for MSTN을 수정란에 세포질 microinjection 하였다. 생산된 배반포는 26마리에 이식을 진행하고, 17마리의 송아지를 얻었다. 그 중 3마리에서 MSTN 돌연변이가 관찰이 되었다. 태어난 MSTN 돌연변이 소에서 off-targeting 영향과 혈액검사 결과 건강상 문제가 없음이 확인되었다. 다음으로, #6, #17 MSTN 돌연변이가 생식선 전이가 되는지를 수정란 수준에서 확인하였다. #6과 #17의 체외수정으로 생산된 배반포를 수란우에 이식을 하여 성공적으로 F1 송아지를 생산하였다. 태어난 송아지에서는 MSTN 돌연변이를 보여주었으며, 건강상에 문제는 관찰되지 않았다. 본 연구는 최초로 CRISPR/Cas9 기반으로 하여 PRNP 돌연변이 소와 외부 유전자가 삽입되지 않은 MSTN 돌연변이 소를 성공적으로 생산하였다. 또한 생식선 전이를 통해 이들의 돌연변이가 다음 세대로 돌연변이가 전달되는 것을 확인하였다. 이러한 연구 결과는 CRISPR/Cas9 시스템을 이용하여 특정 유전자 돌연변이 소를 높은 효율로 생산할 수 있음을 보여주었으며, 축산업 및 수의학 등의 다양한 분야에서 적용될 수 있을 것이다.ABSTRACT 3 TABLE OF CONTENTS 6 LIST OF TABLES 9 LIST OF FIGURES 11 LIST OF ABBREVIATIONS 14 PUBLICATION LISTS 17 PART I. LITERATURE REVIEW 23 1. Production of transgenic cattle 24 2. Gene engineering tools 33 3. PiggyBac transposon 52 PART II. GENERAL METHODOLOGY 63 1. Reagents 64 2. Primary cell culture 64 3. In vitro maturation 64 4. In vitro fertilization and in vitro culture of embryo 65 PART III. GERNERATION OF GENETICALLY ENGINEERED CATTLE 67 Chapter Ⅰ. The production of PRNP gene mutated cattle by CRISPR/Cas9 and piggyBac transposon 68 1. Abstract 69 2. Introduction 71 3. Materials and methods 74 4. Results 88 5. Discussion 125 Chapter II. The production of MSTN gene mutated cattle by CRISPR/Cas9 129 1. Abstract 130 2. Introduction 131 3. Materials and methods 134 4. Results 144 5. Discussion 157 Chapter III. Stable germline transmission from the MSTN gene mutated cattle 162 1. Abstract 163 2. Introduction 165 3. Materials and methods 168 4. Results 176 5. Discussion 190 REFERENCES 197 국문 초록 225박

Excessive Daytime Sleepiness in Tension-Type Headache: A Population Study

Excessive daytime sleepiness (EDS) is a prevalent sleep-related complaint across the general population and has been reported to be associated with headache. Tension-type headache (TTH) is the most commonly encountered headache and accounts for a significant amount of disease burden. However, the association between EDS and TTH is currently scarce. In the present study, we investigated the impact of EDS on the prevalence and clinical presentation of TTH. We utilized data from the Korean Headache-Sleep Study, a national survey that sought to identify headache and sleep characteristics in Korean adults. Participants with an Epworth sleepiness scale score greater or equal to 11 were considered as having EDS. Of the 2,695 participants enrolled, 570 (21.2%) and 313 (11.6%) had TTH and EDS, respectively. EDS was highly prevalent in individuals with chronic tension-type headache (CTTH) than in those without headache (35.7 vs. 9.4%, p < 0.001). The prevalence of EDS in episodic tension-type headache (ETTH) individuals with a headache frequency <1 per month (8.3%, p = 0.511) and ETTH individuals with a headache frequency of 1-14 per month (13.5%, p = 0.054) was not significantly different from that in individuals without headache (9.4%). TTH participants with EDS had a higher headache frequency per month (4.3 ± 8.1 vs. 1.7 ± 4.2, p = 0.013), more severe headache intensity (Visual Analog Scale, 5.0 [3.0-6.0] vs. 4.0 [3.0-6.0], p = 0.008), a higher impact of headache (Headache Impact Test-6 score, 47.1 ± 7.3 vs. 43.5 ± 7.6, p < 0.001), and a higher prevalence of depression (12.7 vs. 3.2%, p < 0.001) than TTH participants without EDS. Consequently, CTTH is associated with higher EDS prevalence compared to ETTH and without headache. Moreover, TTH with EDS had more severe TTH symptoms compared to TTH without EDS.ope

Similarities and differences between bone quality parameters, trabecular bone score and femur geometry

Bone quality is a critical factor that, along with bone quantity, determines bone strength. Image-based parameters are used for assessing bone quality non-invasively. The trabecular bone score (TBS) is used to assess quality of trabecular bone and femur geometry for cortical bone. Little is known about the associations between these two bone quality parameters and whether they show differences in the relationships with age and body mass index (BMI). We investigated the associations between the trabecular bone score (TBS) and femur cortical geometry. Areal bone mineral density (BMD) was assessed using dual energy X-ray absorptiometry (DXA) and the TBS was assessed using iNsight software and, femur geometry using APEX (Hologic). A total of 452 men and 517 women aged 50 years and older with no medical history of a condition affecting bone metabolism were included. Z-scores for TBS and cortical thickness were calculated using the age-specific mean and SD for each parameter. A 'discrepancy group' was defined as patients whose absolute Z-score difference between TBS and cortical thickness was > 1 point. TBS and cortical thickness correlated negatively with age both in men and women, but the associations were stronger in women. Regarding the associations with BMI, TBS provided significant negative correlation with BMI in the range of BMI > 25 kg/m2. By contrast, cortical thickness correlated positively with BMI for all BMI ranges. These bone quality-related parameters, TBS and cortical thickness, significantly correlated, but discordance between these two parameters was observed in about one-third of the men and women (32.7% and 33.4%, respectively). Conclusively, image-based bone quality parameters for trabecular and cortical bone exhibit both similarities and differences in terms of their associations with age and BMI. These different profiles in TBS and FN cortical thickness might results in different risk profiles for the vertebral fractures or hip fractures in a certain percentage of people.ope

삼변수 양 이차형식에 의한 제곱수의 표현

학위논문 (박사)-- 서울대학교 대학원 자연과학대학 수리과학부, 2017. 8. 오병권.In this thesis, we study various properties of representations of squares by ternary quadratic forms. A (positive definite integral) ternary quadratic form is called strongly S-regular if it satisfies a regularity property on the number of representations of squares of integers. We explain the relation between the strongly S-regularity and the conjecture given by Cooper and Lam, and we resolve their conjecture completely. We prove that there are only finitely many strongly S-regular ternary forms up to isometry if the minimum of the non zero squares that are represented by the form is fixed. In particular, we show that there are exactly 207 non-classic integral strongly S-regular ternary quadratic forms representing one.Contents Abstract i 1 Introduction 1 2 Preliminaries 6 2.1 Definitions 6 2.2 Splitting integers 12 2.3 The Minkowski-Siegel formula 13 2.4 Calculations of local densities 16 3 Representations of squares by ternary forms 20 3.1 Indistinguishable by squares 20 3.2 The Cooper and Lam's conjecture 24 4 Strongly S-regular ternary forms 35 4.1 Some properties of strongly S-regular ternary forms 35 4.2 Strongly S-regular ternary forms representing 1 41 4.3 Nontrivial strongly S-regular ternary forms 48 5 Strongly regularity on square classes 56 5.1 Strongly S_t-regular ternary forms 56 5.2 Strongly spinor S_t-regular ternary forms 58 Abstract (in Korean) 64Docto

Comparison of Two DXA Systems, Hologic Horizon W and GE Lunar Prodigy, for Assessing Body Composition in Healthy Korean Adults

Background: Dual-energy X-ray absorptiometry (DXA) is the most widely used method for evaluating muscle masses. The aim of this study was to investigate the agreement between muscle mass values assessed by two different DXA systems. Methods: Forty healthy participants (20 men, 20 women; age range, 23 to 71 years) were enrolled. Total and regional body compositional values for fat and lean masses were measured consecutively with two DXA machines, Hologic Horizon and GE Lunar Prodigy. Appendicular lean mass (ALM) was calculated as the sum of the lean mass of four limbs. Results: In both sexes, the ALM values measured by the GE Lunar Prodigy (24.8±4.3 kg in men, 15.8±2.9 kg in women) were significantly higher than those assessed by Hologic Horizon (23.0±4.0 kg in men, 14.8±3.2 kg in women). Furthermore, BMI values or body fat (%), either extremely higher or lower levels, contributed greater differences between two systems. Bland-Altman analyses revealed a significant bias between ALM values assessed by the two systems. Linear regression analyses were performed to develop equations to adjust for systematic differences (men: Horizon ALM [kg]=0.915×Lunar Prodigy ALM [kg]+0.322, R2=0.956; women: Horizon ALM [kg]=1.066×Lunar Prodigy ALM [kg]-2.064, R2=0.952). Conclusion: Although measurements of body composition including muscle mass by the two DXA systems correlated strongly, significant differences were observed. Calibration equations should enable mutual conversion between different DXA systems.ope

Risk of earlier atherosclerotic cardiovascular disease in women with low bone mineral density

Low bone mineral density (BMD) is associated with higher risk of atherosclerotic cardiovascular disease (ASCVD) in women. We investigated whether the association between low BMD and ASCVD differs according to the age at ASCVD occurrence. We retrospectively analyzed 7932 women aged 50-65 years who underwent dual-energy X-ray absorptiometry. ASCVD was defined as a composite of ASCVD death, myocardial infarction, and ischemic stroke. When we classified participants into no event (n = 7803), early ASCVD (< 70 years) (n = 97), and late ASCVD (≥ 70 years) (n = 32) groups, age gradually increased across groups (median, 58, 60, and 63 years, respectively). However, the estimated BMD T-score at the age of 65 years was lowest in the early ASCVD group (median - 0.9, - 1.1, and - 0.5, respectively). Lower BMD was an independent predictor for early ASCVD (adjusted hazard ratio [95% confidence interval]: 1.34 [1.08-1.67] per 1-SD decrease in T-score), but not for late ASCVD (0.88 [0.60-1.30]). The inverse trend between early ASCVD risk and BMD T-score was consistent regardless of the number of accompanied clinical risk factors. Thus, low BMD is an independent predictor for early ASCVD in women. BMD evaluation can provide prognostic benefit for risk stratification for early ASCVD.ope

Radiation pneumonitis following Yttrium-90 radioembolization: A Korean multicenter study

Objective: To report the incidence of radiation pneumonitis after radioembolization. Methods: In this retrospective study, from May 2009 to July 2021, 782 consecutive patients underwent radioembolization in two institutes. Medical internal radiation dose dosimetry and partition dosimetry were used for glass and resin Yttrium-90-labeled microspheres (90Y-microspheres), respectively. Medical records and radiological findings were retrospectively evaluated with emphasis on the symptomatic radiation pneumonitis. Results: Of the 732 patients with lung shunt study and follow-up, 13 (1.8%) had symptomatic radiation pneumonitis and six patients died due to radiation pneumonitis. Of the 721 patients whose lung doses were calculated, 10 patients who were treated with glass (n = 5) and resin (n = 5) 90Y-microspheres had radiation pneumonitis. No significant statistical difference between glass and resin 90Y-microspheres (p = 0.304) was noted in terms of radiation pneumonitis incidence. Among the patients with radiation pneumonitis, all five patients treated with glass 90Y-microspheres had estimated lung doses > 29 Gy, whereas five patients treated with resin 90Y-microspheres had relatively wide range of lung dose reaching much lower value (13.21Gy). Conclusion: The present study suggests that radiation pneumonitis after radioembolization may occur even though the manufacturer's instructions are followed.ope

Superselective transarterial radioembolization for the treatment of hepatocellular carcinoma

Superselective transarterial radioembolization (TARE) refers the delivery of Y90 at the tumor-feeding segmental or subsegmental arteries. The purpose of TARE would be delivering high dose in the tumor while saving as much normal parenchyma as possible. This concept is similar to the radiation segmentectomy. To identify all tumor feeders, thorough angiography and cone-beam computed tomography are essential. Reported target dose of radiation segmentectomy ranges 222.6–521 Gy. After superselective TARE, the treated segments can show persistent enhancement, and then atrophy combined with capsular retraction. Superselective TARE promises favorable outcomes. It’s reported objective response rates range 64%–95% and toxicities are tolerable in most cases. In conclusion, superselective TARE is a very safe modality for the treatment of HCCs with favorable outcome close to the curative-intent treatments in selected patients.ope