시공간 자료의 다중척도 분석

학위논문(박사)--서울대학교 대학원 :자연과학대학 통계학과,2019. 8. 오희석.This thesis presents a multiscale analysis of spatio-temporal data. The content of this thesis consists of three chapters. First, we suggest an enhancement of the lifting scheme, one of the popular multiscale method, by using clustering-based network design. The proposed method is originally developed for enhancement of graph signal data, and the simulation and real data analysis results show that the proposed method has the advantage to reconstruct the noisy data compared to conventional lifting scheme method. Moreover, the advantage of the proposed method is not limited to the graph signal denoising. It is also shown that the proposed method the proposed neighborhood selection is able to combine with lifting one coefficient at a time (LOCAAT) algorithm, which is a lifting scheme algorithm frequently used in signal denoising. Second, we suggest a new lifting scheme concept which could be applied for streamflow data. It is impossible to apply the original lifting scheme to streamflow data directly because of its complex structure. In this thesis, to adapt the concept of lifting scheme to streamflow data, we suggest a new lifting scheme algorithm for streamflow data with flow-adaptive neighborhood selection, flow proportional weight generation, and flow-length adaptive removal point selection. By using the proposed method, we can successfully construct a multiscale analysis of streamflow data. Simulation study supports the performance of the lifting scheme for streamflow data is competitive for signal denoising. Besides, the proposed methods can visualize the multiscale structure of the network by adding or subtracting observations. Third, multiscale analysis for particulate matter data in Seoul is provided as a case study. We suggest a new method, which is a novel combi- nation of multiscale analysis and extreme value theory. The study starts from the idea that every climate event has its spatial or temporal event lengths. By changing the event area and duration time, we can estimate multiple extreme value parameters using generalized extreme value (GEV) distribution. Besides, we suggest a new property, called piecewise scaling property to combine multiple GEV estimators into a single equation. By using the proposed method, we can construct a return level map with ar- bitrary duration time and event area.이 논문은 다중 척도 분석을 시공간 자료에 응용한 방법들을 제시한다. 첫째, 그래프 신호 자료에서의 다중 척도 분석 방법 중 하나인 리프팅 스킴을 군집 에 기반한 이웃 재설정을 통해 기대 예측 오차를 줄일 수 있음을 보이고 이를 통해 리프팅 스킴의 성능을 향상하였다. 둘째, 공간적으로 복잡하고 방향성이 있는 구조에서 생성된 유량 네트워크 자료에 알맞는 리프팅 스킴을 구성하기 위해 네트워크의 특성을 반영한 이웃 선택, 예측 필터 구성 및 영역 설정으로 유량 네트워크 자료에 대한 리프팅 스킴을 구성하고 시공간 자료에의 확장 가능성을 살펴보았다. 마지막으로 서울특별시 고농도 미세먼지 자료를 다양 한 시간, 공간 및 시공간 집적을 통해 변환한 후 얻어진 일반화 극단값 모형의 모수들의 관계를 수문학에서 사용하는 강도-지속시간-발생빈도 곡선에 매듭 을 추가한 변형된 형태의 강도-지속시간-발생빈도 곡선을 따라 모델링하였고 사례 연구를 통해 원 자료의 복귀 수준 지도를 좀 더 정확히 묘사할 수 있음을 보였다.Abstract i 1 Introduction 1 2 Review: Multiscale analysis 4 2.1 Wavelets 4 2.1.1 Haar transforms 5 2.2 Multiresolution analysis 6 2.3 Lifting scheme 7 2.3.1 Lifting one coefficient at a time (LOCAAT) 11 2.3.2 Other lifting scheme methods 12 3 Enhancement of lifting scheme on graph signal data via clustering-based network design 14 3.1 Graph notations 15 3.2 Previous works 16 3.3 The use of clustering under the piecewise generalized moving average model 17 3.3.1 Piecewise generalized moving average model 18 3.3.2 Optimal UPA assignment under the piecewise homogeneous model 21 3.3.3 Extension to the spatio-temporal data 23 3.4 Simulation study 24 3.4.1 Stochastic block model 24 3.4.2 Image data analysis 26 3.4.3 Blocks signal denoising 29 3.5 Real data analysis 31 3.6 Summary and discussion 32 4 Streamflow lifting scheme 34 4.1 Dataset 36 4.2 Streamflow lifting scheme 37 4.2.1 Neighborhood selection 38 4.2.2 Prediction filter construction 39 4.2.3 Removal point selection 41 4.3 Simulation study 42 4.4 Real data analysis 47 4.5 Summary and further works 50 5 Multiscale analysis for PM10 extremes in Seoul 51 5.1 Data description 51 5.2 Temporal analysis of Seoul extreme PM10 data 54 5.2.1 Temporal aggregation and conventional scale property 54 5.2.2 Temporal multiscale modeling and modified scaling property 56 5.2.3 Result 1: GEV parameter estimation via piecewise linear approximation 57 5.2.4 Result 2: Return level map by the proposed modified scaling approach 62 5.3 Spatio-temporal multiscale analysis of Seoul extreme PM10 data 65 5.3.1 Spatio-temporal aggregation of Seoul extreme PM10 data 65 5.3.2 Result: Areal aggregation of Seoul extreme PM10 data 70 5.4 Summary and discussion 73 6 Concluding remarks 76 A Generalized extreme value distribution 77 B Scaling property theory 79 Abstract (in Korean) 85Docto

Associations of Moderate to Severe Asthma with Obstructive Sleep Apnea

PURPOSE: This study aimed to evaluate the correlation between associating factors of moderate to severe asthma with obstructive sleep apnea (OSA). MATERIALS AND METHODS: One hundred and sixty-seven patients who visited the pulmonary and sleep clinic in Severance Hospital presenting with symptoms of sleep-disordered breathing were evaluated. All subjects were screened with ApneaLink. Thirty-two subjects with a high likelihood of having OSA were assessed with full polysomnography (PSG). RESULTS: The mean age was 58.8±12.0 years and 58.7% of subjects were male. The mean ApneaLink apnea-hypopnea index (AHI) was 12.7±13.0/hr. The mean ApneaLink AHI for the 32 selected high risk patients of OSA was 22.3±13.2/hr, which was lower than the sleep laboratory-based PSG AHI of 39.1±20.5/hr. When OSA was defined at an ApneaLink AHI≥5/hr, the positive correlating factors for OSA were age, male gender, and moderate to severe asthma. CONCLUSION: Moderate to severe asthma showed strong correlation with OSA when defined at an ApneaLink AHI≥5/hr.ope

Risk factors for occurrence and 30-day mortality for carbapenem-resistant Acinetobacter baumannii bacteremia in an intensive care unit.

To assess the risk factors for carbapenem-resistant Acinetobacter baumannii (CRAB) bacteremia and for 30-day mortality in patients with CRAB bacteremia in the intensive care unit (ICU), we conducted a retrospective study in the ICU at Severance Hospital in Korea from January 2008 to December 2009. Patients who acquired CRAB bacteremia in the ICU were enrolled as the case group and patients whose specimens of blood culture, sputum/endotracheal aspirate and urine revealed no AB were enrolled as controls. The case group comprised 106 patients and 205 patients were included as controls. Risk factors independently associated with CRAB bacteremia included prior chemotherapy or radiotherapy treatment (Odds ratio [OR], 3.6; P = 0.003), recent central venous catheter insertion (OR, 5.7; P < 0.001) or abdominal drainage insertion (OR, 21.9; P = 0.004), the number of antibiotics treated with (OR, 1.3; P = 0.016), and respiratory failure in the ICU (OR, 2.5; P = 0.035). The 30-day mortality was 79.8%. Renal failure during ICU stay was independently associated with 30-day mortality (OR, 3.7; P = 0.047). It is important to minimize invasive procedures, and to restrict excessive use of antibiotics, especially in immunocompromised patients, in order to prevent the development of CRAB bacteremia. Greater concern for CRAB bacteremia patients is needed when renal failure develops during ICU stay.ope

A Case of Brucellar Spondylitis with Multiple Spine Involvement

Brucellosis, a zoonosis with world wide distribution, is a systemic infection that affects several organs and has protean presentation. Although spondylitis is universally the most common complication of brucellosis and difficult to treat, there is no consensus on the preferred combination of antibiotics use. The authors report a case of a 58-year-old male patient with brucellar spondylitis involving several vertebrae. Diagnosis was made by positive blood culture and magnetic resonance imaging. The authors use a combination method of doxycycline, ciprofloxacin and streptomycin for a period of 3 months. The systemic symptoms were improved after treatment.ope

Prediction of methicillin-resistant Staphylococcus aureus in patients with non-nosocomial pneumonia

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as an important cause of not only hospital acquired pneumonia, but also non-nosocomial pneumonia. However, the risk factors for non-nosocomial MRSA pneumonia are not clearly defined. Our objective was to identify risk factors at admission that were associated with non-nosocomial MRSA pneumonia. METHODS: We evaluated 943 patients admitted to a university-affiliated hospital with culture-positive bacterial pneumonia developed outside the hospital from January 2008 to December 2011. We compared the clinical characteristics between MRSA and non-MRSA pneumonia, and identified risk factors associated with MRSA pneumonia. RESULTS: Of 943 patients, MRSA was identified in 78 (8.2%). Higher mortality was observed in MRSA than in non-MRSA patients (33.3% vs. 21.5%; P = 0.017). In a logistic regression analysis, MRSA pneumonia was observed more frequently in patients with a previous history of MRSA infection (OR = 6.05; P < 0.001), a PSI score ≥120 (OR = 2.40; P = 0.015), intravenous antibiotic treatment within 30 days of pneumonia (OR = 2.23; P = 0.018). By contrast, non-MRSA pneumonia was observed more often in patients with a single infiltrate on chest radiography (OR = 0.55; P = 0.029). CONCLUSIONS: Anti-MRSA antibiotics could be considered in hospitalized non-nosocomial patients with several risk factors identified herein. The presence or absence of these factors would provide useful guidance in selecting initial empirical antibiotics.ope

Comparison of Methicillin-Resistant Staphylococcus aureus Community-Acquired and Healthcare-Associated Pneumonia

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as an important cause of not only healthcare-associated pneumonia (HCAP) but also community-acquired pneumonia (CAP). We determined the impact of MRSA on differences in clinical characteristics, courses, and outcomes between CAP and HCAP. MATERIALS AND METHODS: We conducted a retrospective observational study on 78 adult patients admitted with MRSA pneumonia at a university-affiliated tertiary hospital between January 2008 and December 2011. We compared baseline characteristics, chest radiographs, treatment outcomes, and drug resistance patterns between the CAP and HCAP groups. RESULTS: Of the 78 patients with MRSA pneumonia, 57 (73.1%) were HCAP and 21 (26.9%) were CAP. MRSA infection history in the previous year (29.8% vs. 14.3%, p=0.244) tended to be more common in HCAP than in CAP. Despite similar Pneumonia Severity Index scores (151 in CAP vs. 142 in HCAP), intubation rates (38.1% vs. 17.5%; p=0.072) and intensive care unit admission (42.9% vs. 22.8%; p=0.095) tended to be higher in the CAP group, while 28-day mortality was higher in the HCAP group (14.3% vs. 26.3%; p=0.368), although without statistical significance. All patients showed sensitivity to vancomycin and linezolid; meanwhile, HCAP patients showed greater resistance to gentamicin than CAP patients (58.3% vs. 16.6%; p=0.037). The median total hospital charges were 6899 American dollars for CAP and 5715 American dollars for HCAP (p=0.161). CONCLUSION: MRSA pneumonia showed significantly differences in baseline characteristics, chest radiographs, treatment outcomes, and medical expenses between HCAP and CAP groups.ope

A Case of Pulmonary Sarcoidosis Combined with Neurosarcoidosis

Sarcoidosis is a multi-systemic syndrome of an unknown etiology, and it is characterized by the formation of multiple noncaseating granulomas that disrupt the architecture and function of the tissues in which they reside. The most commonly affected organs are lung, skin and lymph nodes. Overt clinical involvement of the nervous system is uncommon and this occurs in about 5% of all patients during the course of their disease. The most common manifestations are granulomatous leptomeningitis, cranial nerve palsy, electrolyte or other endocrinologic abnormalities, but isolated memory impairment is a rare manifestation. This is a case of 59 years-old male with recent memory impairment, and he was previously diagnosed with pulmonary sarcoidosis by transbronchial lung biopsy. The brain MRI imaging revealed the leptomeningeal and parenchymal involvement of sarcoidosis. He was treated with high dose corticosteroid and his memory function was improved to nearly a normal level. We report here on a case of successful treatment of pulmonary sarcoidosis combined with neurosarcoidosis with using high dose corticosteroid, and the patient presented with recent memory impairment.ope

Utility of Routine Culture for Tuberculosis from Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration in a Tuberculosis Endemic Country

BACKGROUND: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a technique developed to allow mediastinal staging of lung cancer and also to evaluate intrathoracic lymphadenopathy. In a tuberculosis-endemic area, tuberculosis should be considered as an etiology of mediastinal lymphadenopathy. The aim of this study was to investigate the utility of the routine culture for tuberculosis from specimens of EBUS-TBNA. METHODS: We prospectively performed routine culture for tuberculosis from aspiration or core biopsy specimens got from 86 patients who had undergone EBUS-TBNA due to mediastinal lymphadenopathy between March 2010 and March 2011. RESULTS: A total of 135 lymph node aspiration and 118 core biopsy specimens were included in this analysis. We confirmed the malignancy in 62 (72.9%), tuberculosis in 7 (8.1%), sarcoidosis in 7 (8.1%), asperogillosis in 2 (2.3%) and pneumoconiosis in 2 (2.3%) patients. One lung cancer patient had pulmonary tuberculosis coincidentally and 5 patients had unknown lymphadenopathy. The number of positive culture for Mycobacterium tuberculsosis by EBUS-TBNA is 2 (1.5%) from 135 lymph node aspiration specimens and 2 (1.7%) from 118 core biopsy specimens. Out of eight patients confirmed with tuberculosis, only one patient had positive mycobacterial culture of aspiration specimen from EBUS-TBNA without histopathologic diagnosis. CONCLUSION: These results propose that routine culture for tuberculosis from EBUS-TBNA may not provide additional information for the diagnosis of coincident tuberculous lymphadenitis. However, if there is any possibility of tuberculous lymphadenopathy or pulmonary tuberculosis, it should be considered to perform EBUS-TBNA in patients who have negative sputum AFB smears or no sputum production.ope

A Case of Pneumothorax Caused by Cystic Lung Metastasis of Angiosarcoma

Angiosarcoma is a rare but highly malignant tumorthat usually arises in the scalp or face of elderly males. Distant metastases favor the lung, liver, lymph nodes and skin. Metastatic pulmonary angiosarcoma commonly takes the form of a nodule but can sometimes appear as a thin-walled cyst. We report a case of 65 years-old male with a spontaneous pneumothorax, who underwent excision and radiotherapy for an angiosarcoma of the scalp 2 years ago. A chest CT scan revealed multiple cysts in the lung. The video-assisted thoracoscopic lung biopsy demonstrated subpleural cysts without tumor cells. A skin biopsy of the scalp showed an angiosarcoma. This case was diagnosed as a recurrence of an angiosarcoma with a supposed lung metastasis. This case suggests that a spontaneous pneumothorax in elderly people may be secondary to a pulmonary metastasis from an angiosarcoma of the scalp.ope

피리미딜 설퍼 밴조에이트 아미노산 유도체의 합성

Thesis (master`s)--서울대학교 대학원 :화학과 유기화학전공,1995.Maste