해상 부이용 소형 수직축 풍력발전기 설계 및 전산해석

오민우,김동현 한국풍공학회 2012 한국풍공학회지 Vol.16 No.2

In this study, the patented small vertical-axis wind turbine (SVAWT) of ocean bouy for power supply has been developed and conducted in a variety of experience. In order to verify structural and vibration safety, advanced engineering technologies with self-developed design program, computational fluid dynamics (CFD), finite element method (FEM), and computational structural dynamics (CSD) methods are used. Special loading and vibration conditions due to the wave induced dynamic motion of ocean buoy are also considered herein. In this design, specially designed and patented airfoil shape is tested and applied to yield maximum generated power output under the limited installation space of the ocean buoy. Several SVAWT models mounted on the buoy have been constructed and are being tested in the sea. 본 연구는 해상용 부이(bouy)의 전원공급용 풍력 발전기 개발하였으며, 이는 특허 기술 및 SVAWT 모델 개발의 다양한 경험을 바탕으로 실시되었다. 구조 및 진동 안전성의 확인을 위한 방법으로 자체 개발한 디자인 프로그램과 첨단 공학 기술, 전산 유체 역학, 유한 요소법 및 전산 구조 역학이 사용되었다. 특별 로딩 및 해양 부이의 동적 움직임을 유도해서 파도에 의한 진동 조건으로도 간주되었다. 이 디자인은 특별 설계되었고, 특허 에어포일 형상은 테스트를 거쳐 바다 부이의 제한된 설치 공간에 따라 최대 출력을 얻는데 적용되었다. 여러 SVAWT 모델이 구축 되었으며 실제로 부이에 장착되어 바다에서 테스트 중이다.

Major environmental factors and traits of invasive alien plants determining their spatial distribution

오민우,허윤정,이은주,이효혜미 한국생태학회 2021 Journal of Ecology and Environment Vol.45 No.4

Background: As trade increases, the influx of various alien species and their spread to new regions are prevalent and no longer a special problem. Anthropogenic activities and climate changes have made the distribution of alien species out of their native range common. As a result, alien species can be easily found anywhere, and they have nothing but only a few differences in intensity. The prevalent distribution of alien species adversely affects the ecosystem, and a strategic management plan must be established to control them effectively. To this end, hot spots and cold spots were analyzed according to the degree of distribution of invasive alien plants, and major environmental factors related to hot spots were found. We analyzed the 10,287 distribution points of 126 species of alien plants collected through the national survey of alien species by the hierarchical model of species communities (HMSC) framework. Results: The explanatory and fourfold cross-validation predictive power of the model were 0.91 and 0.75 as AUC values, respectively. The hot spots of invasive plants were found in the Seoul metropolitan area, Daegu metropolitan city, Chungcheongbuk-do Province, southwest shore, and Jeju island. Generally, the hot spots were found where the higher maximum temperature of summer, precipitation of winter, and road density are observed, but temperature seasonality, annual temperature range, precipitation of the summer, and distance to river and sea were negatively related to the hot spots. According to the model, the functional traits accounted for 55% of the variance explained by the environmental factors. The species with higher specific leaf areas were more found where temperature seasonality was low. Taller species preferred the bigger annual temperature range. The heavier seed mass was only preferred when the max temperature of summer exceeded 29 °C. Conclusions: In this study, hot spots were places where 2.1 times more alien plants were distributed on average than non-hot spots (33.5 vs 15.7 species). The hot spots of invasive plants were expected to appear in less stressful climate conditions, such as low fluctuation of temperature and precipitation. Also, the disturbance by anthropogenic factors or water flow had positive influences on the hot spots. These results were consistent with the previous reports about the ruderal or competitive strategies of invasive plants instead of the stress-tolerant strategy. The functional traits are closely related to the ecological strategies of plants by shaping the response of species to various environmental filters, and our result confirmed this. Therefore, in order to effectively control alien plants, it is judged that the occurrence of disturbed sites in which alien plants can grow in large quantities is minimized, and the river management of waterfronts is required. Background: As trade increases, the influx of various alien species and their spread to new regions are prevalent and no longer a special problem. Anthropogenic activities and climate changes have made the distribution of alien species out of their native range common. As a result, alien species can be easily found anywhere, and they have nothing but only a few differences in intensity. The prevalent distribution of alien species adversely affects the ecosystem, and a strategic management plan must be established to control them effectively. To this end, hot spots and cold spots were analyzed according to the degree of distribution of invasive alien plants, and major environmental factors related to hot spots were found. We analyzed the 10,287 distribution points of 126 species of alien plants collected through the national survey of alien species by the hierarchical model of species communities (HMSC) framework. Results: The explanatory and fourfold cross-validation predictive power of the model were 0.91 and 0.75 as AUC values, respectively. The hot spots of invasive plants were found in the Seoul metropolitan area, Daegu metropolitan city, Chungcheongbuk-do Province, southwest shore, and Jeju island. Generally, the hot spots were found where the higher maximum temperature of summer, precipitation of winter, and road density are observed, but temperature seasonality, annual temperature range, precipitation of the summer, and distance to river and sea were negatively related to the hot spots. According to the model, the functional traits accounted for 55% of the variance explained by the environmental factors. The species with higher specific leaf areas were more found where temperature seasonality was low. Taller species preferred the bigger annual temperature range. The heavier seed mass was only preferred when the max temperature of summer exceeded 29 °C. Conclusions: In this study, hot spots were places where 2.1 times more alien plants were distributed on average than non-hot spots (33.5 vs 15.7 species). The hot spots of invasive plants were expected to appear in less stressful climate conditions, such as low fluctuation of temperature and precipitation. Also, the disturbance by anthropogenic factors or water flow had positive influences on the hot spots. These results were consistent with the previous reports about the ruderal or competitive strategies of invasive plants instead of the stress-tolerant strategy. The functional traits are closely related to the ecological strategies of plants by shaping the response of species to various environmental filters, and our result confirmed this. Therefore, in order to effectively control alien plants, it is judged that the occurrence of disturbed sites in which alien plants can grow in large quantities is minimized, and the river management of waterfronts is required.

자중조절 기능이 있는 해상풍력 지지구조의 하중 및 구조해석

오민우,김동현,김기하,김석태,Oh, Minwoo,Kim, Donghyun,Kim, Kiha,Kim, Seoktae 한국전력공사 2016 KEPCO Journal on electric power and energy Vol.2 No.3

해상풍력터빈 시스템은 크게 상부의 풍력터빈과 하부의 지지구조로 구성된다. 해상풍력발전은 육상용 풍력발전보다 우수하다는 평가가 지배적이지만 육상용 풍력발전에서 고려되지 않는 파랑에 의한 주기적인 하중이 추가로 고려되기 때문에 다양한 외부 환경조건에 대하여 높은 안정성 확보가 요구된다. 본 연구에서는 전산유체역학 기법을 활용하여 설계된 해상풍력 하부구조에 대한 하중해석을 수행하고 유한요소해석을 통해 설계된 자중조절형 해상풍력 기초에 대한 구조 건전성을 검토하였다. Offshore wind turbines are divided into an upper wind turbine and a lower support structure. Offshore wind turbine system is required to secure high reliability for a variety of external environmental conditions compared to ground wind turbines because of additional periodic loads due to ocean wave and current effects. In this study, extreme load analyses have been conducted for the designed offshore wind turbine foundation with weight control functionality using computational fluid dynamics (CFD) then structural analyses have been also conducted to investigate the structural design requirement.

An Optimization of Electrochemical Etching Conditions for Gold Nanotips Fabrication

오민우,정해은,박두재,장문규,반세빈,최수봉 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.9

We demonstrate a series of experiments to find optimized electrochemical etching condition for fabricating gold nanotip, using square-wave voltage as a bias and using hydrochloric acid diluted by acetone as an etchant. We confirmed that the dilution ratio of 3 : 1 between hydrochloric acid and acetone give the smallest tip apex diameter which reproduces our previous result. More importantly, by varying applied bias condition and immersion depth of the platinum ring used as a cathode inside the etchant, we found that the smaller tip apex diameter is achieved when both the amplitude and duty cycle get higher. The success rate, which we define the number of tips having meaningfully less diameter out of total number of tried tips, is also discussed.

전개형 붐 구조를 이용한 전개형 우주 매니퓰레이터 설계

오민우(Min-Woo Oh),이대영(Dae-Young Lee) 한국항공우주학회 2023 한국항공우주학회 학술발표회 논문집 Vol.2023 No.6

종이접기 구조를 적용한 우주 임무용 전개형 로봇팔 설계

오민우(Min-Woo Oh),이대영(Dae-Young Lee) 한국항공우주학회 2023 한국항공우주학회 학술발표회 논문집 Vol.2023 No.11

초등교사의 가상현실(VR) 스포츠실 운영 경험 연구

오민우(Oh, Min-Woo),김수연(Kim, Sue-Yeon),원영신(Won, Young-Shin) 한국체육과학회 2021 한국체육과학회지 Vol.30 No.3

The purpose of this study is to find a way to increase the educational utilization of School Virtual Reality (VR) Sports classroom in primary school. The research questions of this study are: First, what are the experiences of primary school teachers regarding the operation of the VR sports classroom? Second, what are the educational effects and limitations of the VR sports classroom in students learning recognized by the teachers. To this end, qualitative research methods were applied to analyze those research topics and in-depth interviews were conducted with teachers in four primary schools that operate virtual reality classrooms. The results for each research question are followed. First, the primary school teachers who participated in the study thought that the activities of the students in the VR sports classroom have a positive influence on the students through the experiences of operating it. Second, the teachers thought it was difficult to secure budgets and spaces for the VR sports classroom but educational effects, such as motivation and interests of physical activity had been increased through the VR sports classroom activities. For the improvement of the VR sports classroom practices in primary schools, the central platform is highly needed along with the capacity building of VR sports class teachers with the strong support from the education ministries. If so, it will be used as a convergence education as well as physical education in primary school

오염하천(진위천)의 환경평가를 위한 생물지수간 적용성 비교분석

오민우 ( Min Woo Oh ),이옥민 ( Ok Min Lee ),송호복 ( Ho Bok Song ),박선진 ( Sun Jin Park ),송미영 ( Mee Young Song ),공동수 ( Dong Soo Kong ) 한국물환경학회 2011 한국물환경학회지 Vol.27 No.6

Jinwi Stream is considerably polluted. The urban development in a Jinwi Stream basin can make state of aquatic ecosystem worse. However, researches for aquatic ecosystems in Jinwi Stream are insufficient. In this study, biotic indices of periphytic diatoms (DAIpo and TDI), benthic macroinvertebrates (EPT, KSI and ESB) and fish (IBI) were compared with the annual water quality data. Benthic macroinvertebrates indices showed highly significant correlations with concentrations of organic materials and nutrients, while DAIpo, TDI and IBI showed low correlations with them. In particular, ESB can be considered as an useful indicator that reflects the degree of diversity and abundance of biotic community as well as water quality. In polluted and disturbed streams as Jinwi Stream, DAIpo, TDI and IBI appeared to be not available for evaluating and discriminating the water quality, although they have been known as good indices in general streams.

등가타워 모델링기법을 이용한 수직축 풍력발전기 운전 진동시험

오민우(Min-Woo Oh),김동현(Dong-Hyun Kim),추헌호(Heon-Ho Choo),신요셉(Yo-Seph Shin) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.4

해상풍력 해저케이블 하역용 유압식 코일링 암 구조설계 및 해석

김명환,김동현,오민우,Kim, Myung-Hwan,Kim, Dong-Hyun,Oh, Min-Woo 한국전산구조공학회 2013 한국전산구조공학회논문집 Vol.26 No.1

본 논문에서는 해저케이블 부두 하역용 장비인 코일링 암(coiling arm)에 대한 국산화 자체개발 내용 중 구조설계 및 해석결과 내용을 제시하였다. 상세 구조설계를 위해 3차원 CAD 프로그램을 이용하여 고 정밀도의 모델링을 수행하였고, 유한요소 기법을 이용하여 전산구조해석을 수행하였다. 코일링 암의 활용 목적에 맞추어 하역대상 케이블을 선박에서 케이블 탱크로 하역시 효과적으로 가이드 할 수 있도록 베어링 및 롤러 부품을 설계하여 메인 암이 회전하고 케이블 가이드가 이동할 수 있도록 하였고, 기존의 외국 모델에서 사용하던 와이어 및 모터 시스템을 이용한 케이블 가이드 작동방식을 유압 시스템을 이용한 작동방식으로 변경하여 원가절감을 달성하면서 사용자가 직관적으로 작동할 수 있도록 설계하였다. 장비 자체의 자중 및 하역 케이블 하중조건에 대한 응력 해석을 수행하였고, 유압시스템의 과작동에 따른 파손 가능성을 고려하였다. 케이블 가이드의 운동 및 설치 지면의 경사도에 따른 전복 안전성 해석을 수행하였으며, 설치장소의 풍하중 효과도 추가로 고려하였다. 본 연구를 통해 기존 수입품 코일링 암의 작동방식 개선과 독자적인 구조설계 및 해석 방법을 확립하였으며, 실제 국내 최초로 자체 개발된 제품의 현장설치 완료 및 하역작업의 효율적이고 정상적인 운영을 완료 및 검증하였다. Structural design and analysis of a coiling arm unloading machine for submarine cable have been originally conducted in this study. Three-dimensional CAD modeling process is practically applied for the structural design in detail. Finite element method(FEM) and multi-body dynamics(MBD) analyses are also used to verify the safety and required motions of the designed coiling arm structure. The effective moving functions of the designed coiling arm with respect to rotational and radial motions are achieved by adopting bearing-roller mechanical parts and hydraulic system. Critical design loading conditions due to its self weight, carrying cables, offshore wind, and hydraulic system over operation conditions are considered for the present structural analyses. In addition, possible inclined ground conditions for the installation of the designed coiling arm are also considered to verify overturn stability. The present hydraulic type coiling arm system is originally designed and developed in this study. The developed coiling arm has been installed at a harbor, successfully tested its operational functions, and finished practical unloading mission of the submarine cable.