OpenFAST와 X-SEA를 이용한 고정식 및 부유식 해상풍력 구조물의 연성동적해석 소프트웨어 개발

지광습,김기두 한국풍력에너지학회 2020 풍력에너지저널 Vol.11 No.2

Coupled dynamic analysis between wind turbines and substructures in fixed and floating offshore wind turbine structures is currently a challenge. The 3D finite element analysis software X-SEA coupled with the OpenFAST program is therefore developed and discussed in this paper. The current version of X-SEA includes the results of extensive research and development based on the finite element program XFINAS, which was originally developed in Imperial College London. The X-SEA solution ranges from simple static to highly advanced dynamic analysis applied to the offshore structures. Autocad is used as pre- and post-processor of X-SEA. The X-SEA program is specialized in offshore projects, including nonlinear structural analysis, dynamic response analysis due to wind, current, waves, and seismic loads, impact dynamics and collapse analysis. X-SEA can also carry out fatigue analysis for tubular steel structures in frequency and time domain. Furthermore, the code checks of steel members with several offshore standards: AISC, API, DNV, Euro-code, ISO and NORSOK, are available in X-SEA for the design of offshore structures. The program has been validated with a standard commercial package called the Structural Analysis Computer System. The theoretical background of X-SEA software is also summarized.

Algorithm for sea fog monitoring with the use of information technologies

Heo, Ki‐,Young,Park, Suhyun,Ha, Kyung‐,Ja,Shim, Jae‐,Seol John Wiley Sons, Ltd 2014 Meteorological applications Vol.21 No.2

<P>Sea fog occurs frequently around the Korean Peninsula during April to July and is considered a major marine meteorological disaster, causing serious transport accidents and socioeconomic losses. Fog-related marine accidents represent 29.5% of the total marine accidents in Korea, which mainly occur along domestic ship routes during night time. In this study, an algorithm for sea fog monitoring using information technologies was developed to reduce fog-related marine accidents and to manage marine transportation, offshore and coastal fisheries, and naval operations. A dual channel difference (DCD) method using the 3.9 and 10.8 mu m channels and texture-related measurements from the Multi-functional Transport Satellite (MTSAT) is applied to detect sea fog. To delineate the probable area of sea fog, the threshold value of - 2.0 K on the DCD is regarded as an indication of areas of sea fog and low cloud. A Laplacian calculation of the 10.8 mu m brightness temperature is proposed as the texture-related measurement for sea fog. The threshold value of the Laplacian calculation is 0.1. An algorithm based on a combination of information technology (IT)-based navigation and sea fog detection technologies was developed to provide warnings to sea-going ships that may encounter fog-related danger. The algorithm checks the geometric relationship between the detected sea fog area and parameters related to the ship, such as its current position, sailing direction and speed, and sailing route. If the algorithm determines that the ship may be in danger, a warning is provided to the ship and a change of route is recommended. Copyright (c) 2012 Royal Meteorological Society</P>

황해 남동부 표층 해양 퇴적물의 광물 분포 : 2010년 한국해양연구원 탐사 시료

조현구,김순오,이희일,신경훈 韓國鑛物學會 2011 광물과 암석 (J.Miner.Soc.Korea) Vol.24 No.3

2010년 해양연구원의 황해 남동부 탐사에서 채취된 67개 표층 퇴적물 시료에 대하여 정량X선 회절분석법을 이용하여 광물조성을 구하였다. 황해 표층 퇴적물은 주구성광물(석영 49.1%, 사장석 13.0%, 알카리 정석 9.3%), 정토광불, 방해석 빛 아라고나이트 등으로 구성되어 있다. 점토광물 중에는 일라이트(9.4%)가 가장 않고, 녹니석(4.6%) 이 두 번째로 많으며, 카올리나이트(0.8%)는 매우 소량 들어 있다. 석영과 알카리장석은 조립질 퇴적물, 각섬석과 점토광물들은 세립질 퇴적물에 농집되는 경향을 나타낸다. 석영, 사장석, 알카라장석, 녹니석 및 카올리나이트 함량은 황해 중앙 니질대의 남단에 해당되는 니질대 1에서 높고, 일라이트 함량은 황해 남동 니질대의 일부인 니질대 2에서 높다. 이와 같은 구성광물의 차이는 세립질 퇴적물의 근원지가 다름을 시사하며, 황해 남동 니질대는 주로 한반도 서해안의 금강과 영산강으로부터 운반되었을 것으로 판단된다. Mineral compositions of 69 southeastern Yellow Sea surface sediments collected at the Korea Ocean Research and Development Institute (KORDI) cruise in 2010, were determined using the quantitative X-ray diffraction analysis. Southeastern Yellow Sea surface sediments are composed of major minerals (quartz 49.1%, plagioclase 13.0% and alkali feldspar 9.3%), clay minerals, calcite, and aragonite. Illite (9.4%) is the most abundant clay mineral, chlorite (4.6%) is the second, and kaolinite (0.8%) is few. Quartz and alkali feldspar contents are high in coarse-grained sediments, whereas amphibole and clay mineral contents are high in fine-grained sediments. Quartz, plagioclase, alkali feldspar, chlorite, and kaolinite contents are higher, and illite content is lower in mud zone 1 corresponding to south margin of Central Yellow Sea Mud than in mud zone 2, a part of Southeastern Yellow Sea Mud. Difference of mineral composition between two mud zone suggests that source of fine sediment may be different in two mud zone and Southeastern Yellow Sea Mud might be largely supplied from the Keum and Youngsan rivers in southern part of the west coast in the Korean Peninsula.

Land—sea linkage of Holocene paleoclimate on the Southern Bering Continental Shelf

Katsuki, Kota,Khim, Boo-Keun,Itaki, Takuya,Harada, Naomi,Sakai, Hideo,Ikeda, Tomonori,Takahashi, Kozo,Okazaki, Yusuki,Asahi, Hirofumi SAGE Publications 2009 The Holocene Vol.19 No.5

<P>Detailed diatom records within surface and core sediments from the Southern Bering Continental Shelf (SBCS) reveal that the Holocene evolution of sea-ice distribution is associated with low pressure patterns. Holocene sea-ice distribution over the SBCS was mainly controlled by the location of the Aleutian Low. The corresponding paleoceanographic and paleoclimate conditions can be divided into three stages: (1) the early Holocene (before 7000 cal. yr BP) was characterized by extensive sea-ice distribution under two low-pressure cells, which covered the western Bering Sea and the Gulf of Alaska, respectively. (2) Between 3000 and 7000 cal. yr BP, the low-pressure system over the Gulf of Alaska became weak, causing total sea-ice mass over the SBCS to retreat. (3) In the past 3000 years, prevailing southwesterly winds over the SBCS due to the developing Aleutian Low have reduced further sea-ice cover on the SBCS. These paleoclimatic changes were probably a response to ENSO variation. The timings of water mass exchanges on the SBCS coincided with sea-level change along the Alaskan Peninsula. As a result, subsequent morphologic alterations have also influenced the paleoceanographic condition of the SBCS. The effect of the surface coastal water and bottom marine water on the SBCS intensified about 6000 cal. yr BP when sea level increased.</P>

인공위성 합성개구레이더 영상 자료의 해양 활용 - 해상풍 산출을 중심으로 -

장재철,박경애 한국지구과학회 2019 한국지구과학회지 Vol.40 No.5

Sea surface wind is a fundamental element for understanding the oceanic phenomena and for analyzing changes of the Earth environment caused by global warming. Global research institutes have developed and operated scatterometers to accurately and continuously observe the sea surface wind, with the accuracy of approximately ±20o for wind direction and ±2 m s−1 for wind speed. Given that the spatial resolution of the scatterometer is 12.5-25.0 km, the applicability of the data to the coastal area is limited due to complicated coastal lines and many islands around the Korean Peninsula. In contrast, Synthetic Aperture Radar (SAR), one of microwave sensors, is an all-weather instrument, which enables us to retrieve sea surface wind with high resolution (<1 km) and compensate the sparse resolution of the scatterometer. In this study, we investigated the Geophysical Model Functions (GMF), which are the algorithms for retrieval of sea surface wind speed from the SAR data depending on each band such as C-, L-, or X-band radar. We reviewed in the simulation of the backscattering coefficients for relative wind direction, incidence angle, and wind speed by applying LMOD, CMOD, and XMOD model functions, and analyzed the characteristics of each GMF. We investigated previous studies about the validation of wind speed from the SAR data using these GMFs. The accuracy of sea surface wind from SAR data changed with respect to observation mode, GMF type, reference data for validation, preprocessing method, and the method for calculation of relative wind direction. It is expected that this study contributes to the potential users of SAR images who retrieve wind speeds from SAR data at the coastal region around the Korean Peninsula. 해상풍은 해양 현상을 이해하고, 지구 온난화에 의한 지구 환경의 변화를 분석하기 위한 필수 요소이다. 전세계 연구 기관은 해상풍을 정확하고 지속적으로 관측하기 위해 산란계(scatterometer)를 개발하여 운영해오고 있으며, 정확도는 풍향이 ±20°, 풍속이 ±2 m s−1 안팎이다. 하지만, 산란계의 해상도는 12.5-25.0 km로, 해안선이 복잡하고 섬이 많은 한반도 근해에서는 자료의 결측이 빈번하게 발생하여 활용도가 감소한다. 그에 반해, Synthetic Aperture Radar (SAR, 합성개구레이더)는 마이크로파를 활용하는 전천후 센서로, 1 km 이하의 고해상도 해상풍이 산출이 가능하여 산란계의 단점 보완이 가능하다. 본 연구에서는 일반적으로 활용되는 SAR 자료 기반 해상풍 산출 알고리즘인 Geophysical Model Function (GMF, 지구 물리 모델 함수)를 밴드별로 분류하여 조사하였다. 상대 풍향, 입사각, 풍속에 따른 후방산란계수를 L-band Model (LMOD, L 밴드 모델), C-band Model (CMOD, C 밴드 모델), X-band Model (XMOD, X 밴드 모델)에 적용하여 모의하였고, 각 GMF의 특성을 분석하였다. 이러한 GMF를 SAR 탑재 인공위성 자료에 적용하여 산출한 해상풍의 정확도 검증 연구에 대해 조사하였다. SAR 자료 기반 해상풍의 정확도는 영상 관측 모드, 적용한 GMF의 종류, 정확도 비교 기준 자료, SAR 자료 전처리 방법, 상대 풍향 정보 산출 방법 등에 따라 변하는 것으로 나타났다. 본 연구를 통해 국내 연구자들의 SAR 자료 기반 해상풍 산출 방법에 대한 접근성이 향상되고, 고해상도 해상풍 자료를 활용한 한반도 근해 분석에 이바지할 것으로 기대된다.

Reduction of internal climate variability in surface temperature due to sea‐ice loss since the mid‐21st century

Hyun, Seung‐,Hwon,Yeh, Sang‐,Wook,Yoon, Jinho John Wiley Sons, Ltd 2017 International journal of climatology Vol.37 No.15

<P><B>ABSTRACT</B></P><P>Understanding the internal climate variability (ICV) is a principal challenge in projecting future climate change. In this study, we define the ICV in projection of surface temperature as the ensemble spread of surface temperature using a 30‐member ensemble simulated with the Community Earth System Model Large Ensemble (CESM‐LE) experiment, and examine how this ICV changes from the present climate to the future climate under Representative Concentration Pathway 8.5 scenario (RCP8.5). First, ICV is reduced in the future climate, particularly since the mid‐21st century. Such a decrease is primarily due to the reduction of ICV in both the Arctic (70°–90°N) and the Antarctic (65°–80°S). Our analysis further indicates that the decrease in ICV in Arctic is significant during boreal fall (September–October–November), and in particular, it is closely linked to the reduction in sea ice since the early and mid‐21st century. This implies that realistic simulation of the Arctic sea ice is a key in reducing ICV in a changing climate.</P>

황해 남동 이질대 퇴적물의 점토광물분포 및 특성

조현구 ( Hyen Goo Cho ),김순오 ( Soon Oh Kim ),이희일 ( Hi Il Yi ) 한국광물학회 2012 광물과 암석 (J.Miner.Soc.Korea) Vol.25 No.3

황해 남동 이질대 51정점(북부 25정점, 남부 25정점)에서 채취된 표층퇴적물과 황해로 유입되는 하천퇴적물 30정점에 대해서 반정량 X선회절분석법에 의하여 점토광물의 상대조성을 구하였으며 일라이트의 광물학적 특성에 대해서도 조사하였다. 점토광물 조성은 일라이트(61∼75%), 녹니석(14∼24%), 카올리나이트(9∼14%), 스멕타이트(1∼7%) 순으로 존재한다. 황해 남동 이질대의 북부 지역에 서 카올리나이트 함량이 약간 높고, 스멕타이트 함량이 낮은 점을 제외하면, 북부와 남부 지역에서 점토광물 조성은 특별한 차이가 없다. 스멕타이트 함량은 일라이트 함량과 대체적으로 음의 상관관계를 가진다. 일라이트의 광물학적 특징들인 일라이트 결정도(0.18∼0.24 Δº2θ) 역시 북부와 남부 사이에 차이가 없으며, 매우 좁은 범위 내에 속한다. 이번 연구 결과는 황해 남동 이질대의 북부와 남부 퇴적 물은 점토광물조성과 일라이트 특성이 거의 유사함을 지시한다. 황해 남동 이질대 퇴적물은 중국의 황하퇴적물보다 한국의 하천퇴적물과 유사한 특성을 가지지만, 추후 양쯔강 퇴적물을 포함한 조사가 필요할 것으로 판단된다. 점토광물 조성으로부터 황해 남동 이질대 퇴적물은 한국 서해안으로 유입되는 하천으로부터 매우 많은 양이 유래한 것으로 판단된다. 황해 남동 이질대의 매우 많은 퇴적물 공급량과 높은 퇴적 속도는 퇴적물들의 침식과 재동에 의한 것으로 간주된다. 황해 남동 이질대 주변의 조류와 지역적인 해류가 이 지역의 침식과 퇴적 과정에 중요한 영향을 미친 것으로 판단된다. In this study, we determined the relative clay mineral composition of 51 surface sediments index also is not different between two areas and show very narrow range (0.18∼0.24 Δº2θ). Our results reveal that clay mineral composition and illite characteristics are nearly the same between northern and southern part of SEYSM. Characteristics of surface sediments in SEYSM is closer to Korean river sediments than Chinese Hanghe sediments, however it is necessary to investigate further study including Yangtze river sediments, This study conclude that most of surface sediments in SEYSM attribute to the supply of considerable amount of sediments from the nearby Korean rivers. The large sediment budget and high accumulation rate in the SEYSM can be explained by erosion and reworking of surface sediments in this area. Tidal and regional current system around SEYSM might contribute these erosional and depositional regimes.from SEYSM (Southeastern Yellow Sea Mud) (northern part 25, southern part 26) and 30 river sedimentsinflow to Yellow Sea using the semi-quantitative X-ray diffraction analyses. In addition to we analyzed illite characteristics of the same samples. The clay-mineral assemblage is composed of illite (61∼75%), chlorite (14∼24%), kaolinite (9∼14%), and smectite (1∼7%), in decreasing order. The average composition of each clay mineral is not different from northern part to southern part of SEYSM except a little higher kaolinite and lower smectite content in northern part. Smectite content generally has reverse relationship with illite content. Mineralogical characteristics of illite such as illite crystallinity.

주성분분석법을 활용한 황해 남동 이질대 퇴적물의 기원지 연구

조현구 ( Hyen Goo Cho ),김순오 ( Soon Oh Kim ),이윤지 ( Yun Ji Lee ),안성진 ( Sung Jin Ahn ),이희일 ( Hi Il Yi ) 한국광물학회 2014 광물과 암석 (J.Miner.Soc.Korea) Vol.27 No.3

황해 남동 이질대에서 채취된 51개의 표층퇴적물 시료와 황해로 유입되는 한국과 중국의 하천 퇴적물 시료 33개에 대해서 반정량 X선회절분석법을 통한 점토광물의 상대적인 함량을 토대로 주성분분석을 도입하여 해양표층퇴적물의 기원지를 연구하였다. 전체 자료의 98% 이상을 반영하는 제1주성분과 제2주성분을 이용하여 R 프로그램을 통해 주성분분석을 수행하였다. 황해 남동 이질대 퇴적물의 점토광물 함량은 남부 지역과 북부 지역에서 거의 차이가 나지 않으며, 성분도표상에서의 해양퇴적물 분포는 중국의 황하, 양쯔강 퇴적물보다 한국의 하천퇴적물과 더욱 근접한 양상을 보였다. 이러한 통계적 분석 결과를 바탕으로 황해 남동 이질대는 거의 모두가 한국 하천퇴적물로부터 유래했다는 것을 추정할 수 있다. 또한, 황해 남동 이질대에 한국 하천에서 유출되는 양보다 더 많은 퇴적물이 축적된 이유로는 퇴적물의 침식과 재동에 의한 것으로 판단된다. 주성분분석은 한반도 주변 해역 퇴적물의 기원지 연구에 유용하게 사용될 것으로 기대된다. In this study, we tried to determine the origin of fine-grained sediments in Southeastern Yellow Sea Mud patch (SEYSM) using principal component analysis coupled with semi-quantitative X-ray diffraction analysis for 4 major clay minerals. We used 51 marine surface sediments from SEYSM and 33 surface sediments of rivers flowing into the Yellow Sea. We made bioplot diagram using R program with principal component 1 and component 2 because the two components might contain about 98% of all data. The content of each clay mineral in the south and north regions of SEYSM are almost similar. In the biplot, SEYSM sediments distribute close to Korean rivers sediments than Huanghe and Changjiang sediments. Based on these results, we suggest that SEYSM is originated from the Korean rivers sediments. The higher accumulation rate in the SEYSM compared to the sediment discharge from neighboring Korean rivers can be explained by erosion and reworking of surface sediments in this area. The principal component analysis can be used for the provenance research of marine sediments around the Korean Peninsula.

Depositional processes of the Zhushadong and Mantou formations (Early to Middle Cambrian), Shandong Province, China: roles of archipelago and mixed carbonate–siliciclastic sedimentation on cycle genesis during initial flooding of the North China P

LEE, HYUN SUK,CHOUGH, SUNG KWUN Blackwell Publishing Ltd 2011 Sedimentology Vol.58 No.6

<P><B>Abstract</B></P><P>To understand the depositional processes and environmental changes during the initial flooding of the North China Platform, this study focuses on the Lower to Middle Cambrian Zhushadong and Mantou formations in Shandong Province, China. The succession in the Jinan and Laiwu areas comprises mixed carbonate and siliciclastic deposits composed of limestone, dolostone, stromatolite, thrombolite, purple and grey mudstone, and sandstone. A detailed sedimentary facies analysis of seven well‐exposed sections suggests that five facies associations are the result of an intercalation of carbonate and siliciclastic depositional environments, including local alluvial fans, shallowing‐upward carbonate–siliciclastic peritidal cycles, oolite dominant shoals, shoreface and lagoonal environments. These facies associations successively show a transition from an initially inundated tide‐dominated carbonate platform to a wave‐dominated shallow marine environment. In particular, the peritidal sediments were deposited during a large number of depositional cycles. These sediments consist of lime mudstone, dolomite, stromatolite and purple and grey mudstones. These shallowing‐upward cycles generally resulted from carbonate production in response to an increase of accommodation during rising sea‐level. The carbonate production was, however, interrupted by frequent siliciclastic input from the adjacent emergent archipelago. The depositional cycles thus formed under the influence of both autogenetic changes, including sediment supply from the archipelago, and allogenic control of relative sea‐level rise in the carbonate factory. A low‐relief archipelago with an active tidal regime allowed the development of tide‐dominated siliciclastic and carbonate environments on the vast platform. Siliciclastic input to these tidal environments terminated when most of the archipelago became submerged due to a rapid rise in sea‐level. This study provides insights on how a vast Cambrian carbonate platform maintained synchronous sedimentation under a tidal regime, forming distinct cycles of mixed carbonates and siliciclastics as the system kept up with rising relative sea‐level during the early stage of basin development in the North China Platform.</P>

2003~2004년도 이어도 기지 해상 기상 특성 분석

오현미,하경자 한국기상학회 2005 Asia-Pacific Journal of Atmospheric Sciences Vol. No.

<P>The present study examines the meteorological data observed at Ieodo ocean research station, Korea. Evaluation of meteorological data such as wind, pressure, and surface fluxes over open sea has been conducted after reduction of sea level pressure and U10 wind. It is shown that the meteorological data of Ieodo station well represents the characteristics for strong wind cases and cold wave over open sea with weak diurnal variation in air temperature and wind. The surface fluxes of sensible, latent, and friction velocity are regressed to the quadratic equation as a function of wind speed, and the sensible heat flux is sharply increased compared to other fluxes. It is realized that the data obtained from Ieodo station will provide the meteorological characteristics for open sea with strong wind, and a useful data for meteorological phenomena prediction.</P>