탄탈럼 이온 주입을 통한 동맥내 폴리-L-젖산 스텐트의 생체적합성 평가

학위논문(박사) -- 서울대학교대학원 : 의과대학 의학과, 2021.8. 김강민.Objective Biodegradable poly-L-lactic acid (PLLA) with a highly biocompatible surface via tantalum (Ta) ion implantation can be an innovative solution for the problems associated with current biodegradable stents. The purpose of this study is to develop a Ta-implanted PLLA stent for clinical use and to investigate its biological performance capabilities. Methods The effectiveness of tantalum ion implantation on PLLA materials was evaluated by histological examinations, immunohistochemistry, and in vitro tests. The re-endothelialization ability and thrombogenicity were examined through in vitro endothelial cell and platelet adhesion tests. An in vivo swine model was used to evaluate the effects of Ta ion implantation on subacute restenosis and thrombosis. Nitinol self-expandable stents were also deployed for comparison. Angiographic and histologic evaluations were conducted at one, two and three months post-treatment. All parent artery diameters were measured to evaluate the effects of this parameter on the experimental results. Results The Ta-implanted PLLA stent was successfully fabricated, exhibiting a smooth surface morphology and modified layer integration. After Ta ion implantation, the surface properties were more favorable for rapid endothelialization and for less platelet attachment compared to the bare PLLA stent. In an in vivo animal test, follow-up angiography showed no evidence of in-stent stenosis in either group. In a microscopic histologic examination, luminal thrombus formation was significantly suppressed in the Ta-implanted PLLA stent group according to the two-month follow-up assessment (21.2% versus 63.9%, p=0.005). A large parent artery diameter was related to less thrombogenicity (p=0.015 at two months) and neointimal hyperplasia (p=0.020 at one month). However, less thrombogenicity at two months appeared to be more related to Ta ion implantation (p=0.066) than a large parent artery diameter (p=0.204). The Nitinol self-expandable stent was superior in terms of neointimal hyperplasia, inflammation and thrombogenicity compared to the PLLA stent groups. Conclusion The Ta-implant PLLA stents appear to be advantageous in terms of re-endothelialization and anti-thrombogenicity compared to the bare PLLA stents.목적 탄탈럼(Ta) 이온 주입을 통해 생체 적합성이 높은 표면을 가지게 된 생분해성 폴리-L-젖산(PLLA)은 현재 생분해성 스텐트가 가진 문제에 대한 혁신적인 해결 방안이 될 수 있다. 이 연구의 목적은 임상용 Ta-주입 PLLA 스텐트를 개발하고 생물학적 성능을 조사하는 것이다. 방법 PLLA 재료에 대한 Ta 이온 주입의 효과를 조직학적 검사, 면역조직화학 및 체외 실험들을 통해 평가하였다. 체외 환경에서 내피세포 및 혈소판 접착 테스트를 통해 재내피화 능력과 혈전형성도를 실험하였다. 체내 환경에서 Ta 이온 주입이 아급성 재협착 및 혈전형성에 미치는 영향을 평가하기 위해 돼지 모델을 사용하였다. 비교를 위해 Nitinol 자체 확장형 스텐트도 삽입되었다. 혈관 조영술 및 조직학적 평가는 시술 후 1, 2, 3개월에서 이루어졌다. 실험 결과에 미치는 영향을 평가하기 위해 모든 모동맥의 크기가 측정되었다. 결과 Ta-주입 PLLA 스텐트가 성공적으로 제작되었다. 스텐트의 매끄러운 표면 형태와 Ta주입을 통해 수정된 층이 잘 결합되어 있음을 확인하였다. Ta 이온 주입 후, 스텐트의 표면 특성은 생 PLLA 스텐트에 비해 빠른 내피화 및 혈소판이 덜 부착하는 성질을 보였다. 체내 동물 실험에서, 추적 혈관 조영술은 두 그룹 모두에서 스텐트내 협착의 증거를 보여주지 않았다. 스텐트 삽입 두 달 후 시행한 현미경 조직학적 검사에서 Ta-주입 PLLA 스텐트 그룹에서 혈관내 혈전 형성이 유의하게 억제되었다(21.2% 대 63.9% p=0.005). 큰 모동맥 직경은 혈전 형성 억제 (p=0.015, 2개월 추적 관찰) 및 신내막증식 억제 (p=0.020, 1개월 추적 관찰)와 연관이 있었다. 그러나 2개월째 나타난 혈전 형성 억제는 큰 모동맥 직경 (p=0.204)보다 Ta 이온 주입 (p=0.066)과 더 관련이 있는 것으로 나타났다. Nitinol 자체 확장형 스텐트는 PLLA 스텐트 그룹에 비해 신생내막 증식, 염증 및 혈전 형성 측면에서 우수했다. 결론 Ta-주입 PLLA 스텐트는 생 PLLA 스텐트에 비해 재내피화 및 항혈전능력 측면에서 유리한 것으로 보인다.제 1 장 Introduction 1 제 2 장 Materials and methods 3 제 1 절 Stent preparation 3 제 2 절 In vitro test 4 제 3 절 In vivo test 7 제 3 장 Results 10 제 1 절 Surface characterization 10 제 2 절 In vitro test 11 제 3 절 In vivo test 13 제 4 장 Discussion 16 제 5 장 Conclusion 24 참고문헌 26 초록 32 Table 목차 [Table 1] 34 [Table 2] 35 Figure 목차 [Figure 1] 36 [Figure 2] 37 [Figure 3] 38 [Figure 4] 39 [Figure 5] 40 [Figure 6] 41 [Figure 7] 43 [Figure 8] 44 [Figure 9] 45 [Figure 10] 46 [Figure 11] 47 [Figure 12] 49 [Figure 13] 51 [Figure 14] 53 [Figure 15] 54 [Figure 16] 55 [Figure 17] 58 [Figure 18] 60 [Figure 19] 62 [Figure 20] 64 [Figure 21] 65 [Figure 22] 66 [Figure 23] 67박

Design and Implementation of SPAM Filtering System Using User Action and Incremental Machine Learning

With rapidly developing Internet applications, an e-mail has been considered as one of the most popular methods for exchanging information because of easy usage and low cost. The e-mail, however, has a serious problem that users can receive a lot of unwanted e-mails, what we called, SPAM mails, and then the user's mailbox can be grown exponentially. The users need for spending time to pick out the SPAM mails and give a great loss economically. To alleviate the problem, many researchers and companies proposed some filtering technologies. On the other hand, in e-mail client systems, users do different actions according to usefulness of information on mails, and some classification and recommendation systems like GroupLens use the actions to improve the performance. This paper presents a mail filtering system using user actions and incremental machine learning. E-mail data and user actions are collected through some user interface implemented in CGI/Perl. Our proposed system makes use of two models: One is anaction inference model to draw a user action from an e-mail and the other is a mail classification model to decide if an e-mail is SPAM or not. All the two models are derived using incremental learning, of which an algorithm is IB2 of TiMBL. To evaluate our proposed system, we collect 10,000 mails of 12 persons from Hanmail (www.hanmail.net), which is one of the most popular e-mail service providers in Korea. The accuracy is 81 ~ 93% according to each person. Our proposed system outperforms a system that does not use any information about user actions. Consequently, we have shown that information about user actions is useful for e-mail filteringAbstract = ⅴ 제 1 장 서론 = 1 제 2 장 관련 연구 = 3 2.1 쓰레기 편지 차단을 위한 기술적 대응 방법 = 3 2.1.1 편지 주소 수집 차단 기술 = 3 2.1.2 대량 쓰레기 편지 발송 대응 기술 = 4 2.1.3 쓰레기 편지 발송자 신원 확인 기술 = 5 2.1.4 쓰레기 편지 여과 기술 = 6 2.2 기계학습을 이용한 쓰레기 편지 여과 = 7 2.2.1 베이지안 분류를 이용한 쓰레기 편지 여과 = 8 2.2.2 지지벡터를 이용한 쓰레기 편지 여과 = 9 2.2.3 사례기반 학습을 이용한 쓰레기 편지 여과 = 10 2.3 묵시적 피드백 = 12 2.4 편지 학습 말뭉치 = 14 제 3 장 사용자 행동과 점진적 기계학습을 이용한 쓰레기 편지 여과 시스템의 설계 및 구현 = 16 3.1 학습 말뭉치 구축 과정 = 17 3.1.1 전처리 과정 = 17 3.1.2 사전 생성 = 19 3.1.3 사용자 인터페이스를 통한 행동 정보 수집 = 20 3.2 학습 과정 = 22 3.2.1 모델 구축을 위한 자질 추출 = 22 3.2.2 학습을 이용한 모델 생성 = 23 3.3 분류 과정 = 26 제 4 장 실험 및 평가 = 27 4.1 실험 말뭉치 = 27 4.2 성능 평가 방법 = 28 4.3 분류 정확도 평가와 분석 = 29 4.3.1 학습 데이터 양에 따른 분류 정확도 = 29 4.3.2 사용자별 분류 결과 차이 분석 = 30 4.3.3 최적의 분류 결과를 나타내는 학습 데이터 양 = 31 4.4 분류의 증거로 사용되는 행동 패턴 분석 = 32 4.5 쓰레기 편지 여과작업에서 행동 정보의 유용성 여부 평가 = 33 4.6 기존 쓰레기 편지 여과 시스템과의 비교 = 34 제 5 장 결론 및 향후 연구과제 = 36 참고문헌 = 3

Analysis of Ocean Discharges of Municipal Water and its Near-Field Mixing Characteristics

Analysis of Ocean Discharges of Municipal Water and its Near-Field Mixing Characteristics Due to the growth of population and industrial development at the coastal cities, there have been much increase in necessity to effective disposal of the wastewater. The amount of municipal water has been increased rapidly and it is necessary to treat and dispose the wastewater effectively. The recent trend, in terms of disposal of it, is discharge through diffusers into the ocean, either at the coastline or at the deep water, or between these two. For this end, we need to predict near-field characteristics of discharged water. We adopted CORMIX model for the analysis of the near-field behavior of discharged water and made certain comparison with the existing experimental results. We found the early dilution is important, especially for the numerical simulation by a depth averaged hydrodynamic model of diffusion mechanism at the existing flow field. We also applied it to the Pusan Jungang Effluent Outfall System, which is planned to be in the Gamchun harbour and will be completed in 2011. The model output showed the trajectoral variation of dilution and mixing behavior for three cases of outfall system. Dilution differences have been simulated and found the highest dilution condition under the different displacement of outfall system. On the basis of these outputs it will be proposed the optimum outfall system type and location. Through the case study, dilution is dependent on the discharge depth, the ambient velocity and total flow rate. This approach might contribute to deal with serious water quality problems caused by the ocean discharge

A Study on Correlation Analysis of Environmental Factors and Prediction of Topographic Change in the Estuary of Nakdong River

It is very important to understand the mechanism of estuary topographic change for setting up estuary management and treatment methods. In this study, the effects from the land side such as rainfall, river discharge, sediment discharge and the sea side such as tide, tidal current, wave, bottom material(surface sediments) related to the topographic changes of the Nakdong river estuary were investigated and analyzed. Based on the analyzed data, hydrodynamic modeling, topographic modeling, and wave induced current modeling were performed to understand the variation patterns from past to present. As the results of the topographic changes on the Nakdong river estuary, the deltas of the group of alluvial island such as Sinhodo, Myeonghodo, and Eulsukdo formed before 1916 year, were formed by sediment discharge at a location where a slow current velocity occurred in the middle of the river. Jinudo, Daemadeung, and Maenggeummeorideung in front of these are called the first sandbar group. Jangjado and Baekhapdeung the second sandbar group. Sinjado and Doyodeung the third sandbar group. Especially, the construction of river estuary barrage has affected the sediment environment caused the change of sediment supply and transport in the river estuary. In other words, It is considered that the construction of the river estuary barrage has not only slowed the deposition of sediments by slowing down the sediment supply but also accelerated the topographic changes due to the hydraulic effects such as wave and tide. The average annual discharge through the river estuary barrage for the last 13years is 19,274.56×106㎥. According to the discharge, the annual average suspended load is 3,153,995㎥/yr, and the bed load 30,410㎥/yr, which is 1.0% of the suspended load. The sandy contents of surface sediments has been increasing since the construction of river estuary barrage. These results indicate that river sediments were discharged to the offshore on the flood time and the muddy sediments of offshore were moved and sorted by tidal current on ordinary time before construction of the estuary barrage. In addition, it is considered that the sandy sediments moved in front of the sandbar group, the muddy sediments moved to the offshore by tidal current. The mixing branch point before the construction of the river estuary barrage was the front of the Daemadeung, but it was found that the effects of fresh water appears up to the Sinjado and Baekhapdeung. The seawater circulation is governed by the behavior of the river discharge rather than by tidal current. It was confirmed that the flow moved repeatedly upward and downward along the main waterway without being completely mixed, because the freshwater and seawater were stratified. From the analysis of the wave observations of the wave buoys in Geojedo from 2008 to 2017, the ENE series of winter has the highest rate of occurrence by 2008 and 2009, the SW series of summer has the highest rate from 2010 to 2017. This result seems to be related to recent seawater temperature rise. It suggests that the trend of hydraulic impact on the estuaries due to the wave will increase according to recent research results. As the results of analysis of environmental factors correlation related to topographic changes in the river estuary, the river discharge and sediment discharge are directly proportional to the change of sandbar area. The results of surface sediment analysis shows that the high content of sand is distributed at the region far away from the estuary mouth. It seems that high resistance to the external force due to the instantaneous discharge through river estuary barrage and increase of incident wave height due to the gradual increase of the mean sea level and extreme highest tide level. As per the tidal current observations, the currents is also controlled by the river discharge and wave of the external environmental factors. The ebb time is more prevalent than the flood time, and the overall change of current is shown by the discharge through the river estuary barrage. These results are considered to be dominant in the topographic change of the rear side of the sandbar. As the result of the analysis of wave for the last 10 years, the ENE series in winter has the highest occurrence rate in 2008 and 2009, but the SW series in summer has the highest occurrence rate from 2010 to 2017. Therefore, it is necessary to reconsider the summer S series wave. The change of currents after construction of river estuary barrage was analyzed for the pre-post construction of Busan new port. Simulation results show that the current velocity decreases widely nearby the sea side of the Sinjado, Jangjado, Baekhapdeung, and Doyodeung and increases nearby the waterway Sinjado, Janjado, and Dadeadeung. As per the results of the topographic change, the river estuary showed a general deposition dominant phenomenon. These results are influenced by the decrease of the current velocity in ordinary time without the influence of the wave, sediment discharge due to summer river rainfall, the appearance of the Doyodeung, and the wave from offshore in summer and winter rough time. As the result, it is expected that new sandbar will appear on the offshore, and deposition will be strengthened in the tideland near Jinudo and Sinjado, and in Dadaepo and its north side coast. It is also inferred that there will be development in the east-west direction of Jinudo and Sinjado, and littoral movement to the waterway and Dadeapo beach. It is considered that the topographic development of the south side and the east-west side of on the barrier island will be continued. Generally, the contribution analysis shows that i) the increase in current velocity at the narrow waterway was greater than the decrease at the tideland; ii) river discharge was greater at the main waterway than at both the tideland and the front waters of the barrier islands; and iii) the wave impact was the largest in the winter with higher contribution to the erosion. Compared with deposition dominance, which is the result of the topographic change prediction, the impact of each external force condition gives larger erosion, but the combined impact of each external force condition shows deposition dominant. Therefore, the topographic changes of the Nakdong river estuary are considered to be the result of various complex external factors. Since the impact of each external force condition shows a different contribution to each area, above results should be considered when establishing the estuary management plan, but it must be understood as the result of complex interaction.ABSTRACT ⅰ LIST OF TABLES ⅷ LIST OF FIGURES ⅹ 1. 서론 1 1.1 연구 배경 1 1.2 기존 연구 3 1.2.1 낙동강 하굿둑 건설 이전 4 1.2.2 낙동강 하굿둑 건설 이후 4 1.3 연구 목적 및 방법 6 2. 낙동강 하구 사주 지형변화 특성 분석 7 2.1 사주와 간석지 8 2.1.1 간석지 10 2.1.2 사주 10 2.2 사주의 시대적 변천 11 2.2.1 2000년 이전 지형변화 11 2.2.2 2000년 이후 지형변화 26 2.3 사주 지형변화 추이 분석 34 2.3.1 사주 지형변화 분석 34 2.3.2 사주별 지형변화 추이 분석 34 3. 낙동강 하구 환경인자 상관관계 분석 41 3.1 낙동강 하굿둑 방류량 40 3.1.1 낙동강 하굿둑 40 3.1.2 하굿둑 방류 패턴 45 3.1.3 하굿둑 주변 강수량 45 3.1.4 하굿둑 방류량 49 3.2 낙동강 하굿둑 유사량 66 3.2.1 연구 방법 66 3.2.2 결과 분석 70 3.3 해저질(표층 퇴적물) 74 3.3.1 연구 방법 74 3.3.2 결과 분석 85 3.3.3 기존연구 분석 88 3.4 조석 및 조류 93 3.4.1 조석 93 3.4.2 조류 96 3.5 파랑 131 3.5.1 파랑특성 131 3.5.2 기존연구 분석 133 3.6 분석 결과 139 4. 낙동강 하구 지형변화 예측 및 외력조건에 따른 기여도 분석 141 4.1 기존연구 분석 142 4.2 예측 모델의 개요 및 구성 143 4.2.1 적용모형의 개요 143 4.2.2 모형의 구성 171 4.2.3 적용 모형의 검증 183 4.3 지형변화 실험의 결과 분석 188 4.3.1 해수유동 188 4.3.2 지형변화 191 4.3.3 해빈류 200 4.4 외력조건의 지형변화 기여도 분석 226 4.4.1 조석 226 4.4.2 하천 유출량 226 4.4.3 파랑 227 4.4.4 결과 분석 227 5. 결론 및 제언 233 5.1 결론 233 5.1.1 환경인자 조사 및 분석 결과 233 5.1.2 환경인자 상관관계 분석 결과 235 5.1.3 지형변화 예측실험 결과 236 5.1.4 외력조건의 지형변화 기여도 분석 결과 237 5.2 제언 239 참고문헌 240Docto

Revisiting the Art of Pen Varlen (1916-1990): The Migrant Identity of a Korean-Soviet Artist

This thesis examines Pen Varlen (1916-1990), a migrant artist who sought his place in Soviet mainstream culture. Pen was a Korean-Soviet painter during the 1940s to the 1980s at the Ilya Repin Leningrad Institute for Painting, Sculpture, and Architecture (Leningrad Academy of Fine Arts). His works were inspired by his migration and the multi-layered identity formed by the experience. Moreover, he served as a communication channel between Soviet authorities and North Korea to gain a foothold in Soviet society. He also pursued cosmopolitanism, which suited Soviet ideology and its contemporary political aims. Previous scholarship on Pen is mostly focused on his Korean identity, thereby neglecting the assimilative efforts made by the artist. While this thesis acknowledges that Pen retained his Korean identity to a certain degree, it attempts to depart from the conventional interpretations of his works which associate the artist’s entire oeuvre solely with his Korean heritage and nostalgia. Born in a Korean village in the Primorsky region of Russia, Pen studied in Sverdlovsk, and later in Leningrad for higher education in art. Coincidentally, this migration prevented him from being deported to Central Asia along with other Koreans from his hometown in 1937. He continued his studies at the Leningrad Academy of Fine Arts and became an associate professor there. In 1953, when the Korean peninsula was just recovering from the aftermath of the Korean War (June 25, 1950 - July 27, 1953), Pen was dispatched to Pyeongyang as an adviser to the nascent Pyeongyang Institute of Fine Arts. However, after his brief return to Leningrad in 1954, Pen was blocked by the North Korean authorities from revisiting the country. His refusal to become naturalized as a North Korean citizen, along with the purge of Soviet-aligned personnel in North Korea, had worked against him. He developed a complex and multi-layered migrant identity through repeated contact with and estrangement from Korean society. The discrepancy between his ethnicity (Korean) and legal citizenship (Soviet) left Pen in a position tangential to both cultures. To survive in the central stage of the Soviet art world, he assumed the role of a ‘model minority’ citizen by maintaining his Korean identity while pledging allegiance to the Soviet ideology. His frequent depiction of North Korean subjects, as well as his use of Korean inscriptions, can be seen as a survival strategy. He also painted a large portrait of a Korean-Soviet ‘Socialist Labor Hero’ Alexandra Han to praise the virtue of model minorities and assert his position in the Soviet Union. That Pen used his cultural background to meet the expectations of Soviet viewers is also evident from his etchings in the 1970s, peppered with ‘Oriental’ elements. Pen created numerous works of a ‘cosmopolitan’ nature, such as People of Our Time (1969-1973), the Pushkin Festival series (1975), and images of black people. Simultaneously, with the advent of the high détente (1970-1975), the Soviet Union sought to expand its influence in the developing world. This shift in international affairs coincided with Pen’s personal desire to find a place for himself in the world. If his host culture encompassed the world, he could consider himself a global citizen, instead of an outsider. Two major trends stand out in Pen’s works from the 1980s: first, works that feature masterpieces of the Western art tradition or scenes from his trip to Western countries; second, artworks reminiscent of his hometown in Primorsky or North Korea. The former show that the alleviation of political tension in Soviet society let him focus more on his artistic creation than on propagating state ideology. This shift in the social milieu can be held accountable for the Korean-related works in the mid-1980s. Until then, he had kept the use of his Korean-ness in artworks limited. Thus, along with the development of a cosmopolitan attitude during the 1970s and the heightened sense of security following his promotion to full professor, the changed circumstances of the 1980s helped Pen create art that displayed his Korean identity to a level hitherto unseen.변월룡(Pen Varlen, 1916-1990)은 한국계 소련인 화가로, 1940-80년대에 레닌그라드 미술아카데미에서 수학하고 활동하였다. 변월룡의 작품세계는 이주로 인해 다면화된 그의 정체성과 소련에서의 삶을 개척하기 위한 그의 전략을 반영한다. 그는 레닌그라드에서 자신의 입지를 확보하고자 한인 사회와 소련의 가교 역할을 수행하였으며, 소련의 이데올로기 및 동시대 정책에 부합하는 세계시민주의를 추구하였다. 기존 연구에서는 변월룡이 한인이라는 점이 강조된 데 비해 소련에 동화되기 위한 그의 노력은 상당 부분 간과되었다. 필자는 변월룡에게 한인으로서의 자의식이 남아있었음을 인정하되, 그의 작품세계 전체를 고국에 대한 향수와 결부시키는 기존 해석으로부터 벗어나고자 하였다. 변월룡은 연해주 한인 마을에서 태어났으나 1937년 강제이주 대신 유학길에 올랐으며, 러시아 대도시에서 고등교육을 마치고 소련 엘리트 사회에 진입하였다. 그는 학업을 지속하여 모교인 레닌그라드 미술아카데미에서 교수로 활동하였다. 변월룡은 1953년 전후 북한 미술계의 재건 및 소련 미술 제도의 전수를 목적으로 평양으로 파견되었다. 그러나 1954년 소련으로 돌아온 이후 변월룡은 ‘민족의 배신자’로 낙인찍혀 두 번 다시 북한 땅을 밟지 못하였다. 그는 중앙아시아 강제 이주를 직접 경험하지는 않았지만, 한인 사회와의 접촉과 분리를 거듭하며 그의 정체성은 복잡한 성격을 띠게 되었다. 변월룡은 민족과 국적의 불일치로 인해 한인 집단과 러시아인 집단 양쪽에서 주변적 위치에 놓여 있었다. 그가 소련 중심부에 자리 잡고 활동하기 위해서는 전략을 모색해야 했다. 변월룡은 우선 한인 정체성을 유지하면서도 소련의 국가 이데올로기에 충성하는 ‘모델 마이너리티(model minority)’ 시민의 역할을 자처하였다. 그 일환으로 변월룡은 (1958), (1960)과 같이 북한 테마의 작품을 제작하고 한글 텍스트를 사용하였다. 한편, 사할린 한인으로서 ‘사회주의 노동 영웅’ 칭호를 받은 한슈라의 대형 초상화를 그림으로써 소련 내 모델 마이너리티의 긍정적 역할을 강조하기도 했다. 그 밖에 변월룡이 소련의 기대에 부응하기 위해 자신의 민족적 배경을 활용한 사례로는 동양화적 요소를 차용한 1970년대의 판화들이 있다. 1970년대는 국제정세의 변화가 변월룡의 개인적 관심사와 맞물려 세계시민주의적 작품들이 제작된 시기이다. 1970-75년간 절정을 이룬 미소 데탕트 시기, 소련은 ‘평화로운 공존’의 슬로건을 내걸고 제3세계로의 세력권 확장을 시도하였다. (1969-1973)에는 레닌 시기에 구축된 국제주의적 이상과 러시아 문화가 세계를 포섭한다는 70년대 소련의 야망이 결합되어 있다. 소련의 이러한 태도는 변월룡의 입장에서도 옹호할 만한 것이었다. 변월룡이 거주하는 러시아의 문화가 세계 각지의 민족들을 아우른다면 그 자신도 무소속의 떠돌이가 아니라 ‘세계 시민’이 될 수 있었기 때문이다. 변월룡이 제작한 흑인 이미지에서도 소련의 정치적 요구와 세계시민주의적 발상의 결합이 드러난다. 변월룡의 1980년대 작품에서는 크게 두 가지 경향이 눈에 띈다. 첫째는 해외여행에서 영감을 받거나 서양미술 전통과의 접점을 강조하는 작품들, 둘째는 20여 년 만에 재부상한 북한 테마 및 (1985)이다. 1980년대의 해외여행 작품들은 당시 사회적 분위기가 완화됨에 따라 변월룡도 프로파간다보다는 예술 창작에 몰두하게 되었음을 보여준다. 한편, 변월룡은 1980년대 중반에 이르러 유년기 및 북한 방문기를 회상하는 작품들을 다수 제작하였다. 이전까지 그는 자신의 한인 정체성을 제한적으로만 드러냈다. 그러나 1980년대에는 완화된 사회적 분위기, 세계시민주의적 태도, 아카데미 정교수라는 그의 지위 등이 맞물려 변월룡은 한인 정체성이 두드러지는 작품을 제작할 수 있었다.Ⅰ. 서론 1 Ⅱ. 모델 마이너리티의 문화번역 12 1. 북한과의 연결 통로 12 2. 모델 마이너리티의 초상: 한슈라 24 3. 한인 정체성 및 동양적 모티프의 활용 31 Ⅲ. 소련의 인종, 민족 프로파간다와 세계시민주의 38 1. 세계시민주의의 이상 38 2. 흑인 초상화 41 3. 푸슈킨 축제 53 Ⅵ. 1980년대의 변화 59 1. 해외여행과 서양미술 전통의 활용 59 2. 어머니와 북한 작품들 67 Ⅴ. 결론 74 참고문헌 77 도판 목록 84 도판 91 Abstract 116석

(A)New control method of distributed generation using active droop control in islanded system

학위논문(석사) --서울대학교 대학원 :전기. 컴퓨터공학부, 2009.2.Maste

척수 해변상 혈관종의 보존적 치료

학위논문 (석사)-- 서울대학교 대학원 : 의학과, 2012. 2. 김현집.Introduction There have been many reports about surgical results of spinal cord cavernous angiomas. But it is not well known the natural history of disease when it was conservatively treated. So we analyzed the result of conservative management of spinal cord cavernous angiomas to provide proper treatment strategy. Materials and Methods The patients who visited Seoul National University Hospital and Seoul National University Bundang Hospital for 11 years (2000 – 2010) were investigated. Spinal cord cavernous angiomas were diagnosed by spine MRI. Twenty-four patients treated conservatively were enrolled in this study. Medical records and radiological images were reviewed retrospectively. Neurologic status of patients was classified by McCormick grade and clinical presentation of patients was classified into 4 categories (Type A, B, C, D). Each type A, B, C and D represented asymptomatic, pain only, sensory symptom and motor symptom, respectively. Results Mean age of enrolled patients was 51.1 years old (21 – 68). Numbers of male and female patients were 13 and 11, respectively. Clinical follow-up duration was 52.4 months (6 – 99) and MRI follow-up duration was 32.6 months (3 - 90). Level of spinal cord cavernous angiomas was cervical level in 12 patients, thoracic level in 2 and multiple spine level in 2. Except only one intradural-extramedullary location, all other cavernous angiomas are intramedullary type. Multiple cavernous angiomas were found in 5 patients (20.8%). Among them, 2 patients had family history of cavernous angioma. Nineteen patients (79%) were McCormick grade I, 4 patients (17%) were grade II and one patient (4%) was grade IV. Type A, B, C and D included 5, 5, 7 and 7 patients, respectively. Annual recurrent hemorrhage rate was 1% in this study. Except one patient who was clinically suspected of recurrent hemorrhage, there were no patients who presented with newly-developed neurologic deficits by spinal cord cavernous angiomas during follow-up period. Conclusion In conservatively managed group, recurrent hemorrhage was rare (1%) and clinical outcome was acceptable. Conservative management can be a reasonable treatment strategy, if spinal cord cavernous angiomas are presented with type A, B, C or type D with McCormick grade I or II.서론: 지금까지 많은 척수 해면상 혈관종의 수술적 치료 결과에 대한 많은 연구가 있었다. 그러나 척수 해면상 혈관종을 보존적으로 치료하였을 때 자연경과는 잘 알지 못하는 상태이다. 따라서 척수 해면상 혈관종의 보존적 치료 결과를 분석하여 자연경과를 이해함으로써 치료 계획 수립에 도움을 주고자 한다. 연구재료 및 방법: 서울대학교병원과 분당서울대학교병원에서 2000년부터 2011년까지, 총 11년간 척수 해면상 혈관종 진단을 받은 환자를 대상으로 연구를 시행하였다. 척수 해면상 혈관종은 MRI로 확진 되었으며 보존적 치료를 받은 24명의 환자가 이번 연구에 포함되었다. 의무기록 및 방사선 영상을 후향적으로 조사하였다. 신경학적 상태는 McCormick grade에 따라 분류하였고 임상 양상은 4가지 범주로 (type A, B, C, D) 분류 하였다. 각각의 type A, B, C, D는 무증상, 통증만 있는 경우, 감각 증상만 있는 경우 운동증상만 있는 경우에 해당하였다. 연구 결과: 환자의 평균 연령은 51.1세 (21-68세)였고, 남:여의 비율은 13:11 이었다. 임상적 추적 관찰 기간은 평균 52.4개월 (6-99개월)이었으며 MRI 추적 관찰 기간은 평균 32.6개월 (3-90개월)이었다. 척수 해면상 혈관종의 위치는 경추부 12명, 흉추부 2명, 다발성(경추, 흉추, 요추부) 2명이었다. 척수 해면상 혈관종은 경막내수질외에 위치한 한 명을 제외하고 나머지 모두 수질내에 위치해 있었다. 다발성 해면상 혈관종이 5명의 환자에서 발견이 되었고 (20.8%), 그중 2명에서 가족력이 확인되었다. 19명 (79%)은 McCormick grade I, 3명 (17%)은 grade II, 1명 (4%)은 grade IV였다. Type A, B, C, D에는 각각 5명, 5명, 7명, 7명의 환자가 해당되었다. 연간 재출혈율은 1%였다. 임상적으로 재출혈이 의심되었던 1명을 제외하면, 추적 관찰 기간 동안 척수 해면상 혈관종에 의해 새로운 신경학적 증상이 발생한 환자는 없었다. 결론: 보존적으로 치료를 한 군에서 재출혈은 드물며 (1%) 임상적 결과도 좋았다. 척수 해면상 혈관종이 type A, B, C 또는 McCormick grade I, II 상태의 type D로 발견된다면 보존적 치료가 합리적인 치료 방침이 될 수 있다.Maste