Subtidal Marine Algal Community and Endangered Species in Dokdo and Ulleungdo,Two Oceanic Islands in the East Sea of Korea     

Jung  Seung Wook  Oh  Yoon Sik  Rho  Hyun Soo  Choi  Chang Geun 《Ocean Science Journal》2020,55(4):537-547

Ocean Science Journal - Dokdo and Ulleungdo islands harbor diverse marine algae and are therefore uniquely well-suited for research on marine algae distribution and ecological changes. However,...  相似文献   

Methods for ultimate limit state assessment of ships and ship-shaped offshore structures: Part II stiffened panels     

Jeom Kee Paik  Bong Ju Kim  Jung Kwan Seo 《Ocean Engineering》2008,35(2):271-280

The present paper is Part II of a series of three papers on methods useful for the ultimate limit state assessment of ships and ship-shaped offshore structures. In contrast to Part I [Paik et al., 2007a. Methods for ultimate limit state assessment of ships and ship-shaped offshore structures: Part I unstiffened plates, Ocean Engineering, doi:10.1016/j.oceaneng.2007.08.004] that deals with unstiffened plates, the present paper (Part II) is focused on methods for the ultimate limit state assessment of stiffened plate structures under combined biaxial compression and lateral pressure actions. The object structure is the bottom part of an AFRAMAX-class hypothetical double-hull oil tanker structure designed by IACS common structural rules (CSR) method, that is the same ship studied in Part I. Three candidate methods, namely ANSYS nonlinear finite element method, DNV PULS method, and ALPS/ULSAP method, are employed for the present study. The results and insights developed from the present study are summarized in terms of ultimate strength characteristics of bottom-stiffened plate structures.  相似文献   

Estimation of the Effect of Flushing Time on Oyster Aquaculture Potential in Jaran Bay     

Kim  Jin Ho  Hong  Sokjin  Lee  Won-Chan  Kim  Hyung Chul  Eom  Ki-Hyuk  Jung  Woo-Sung  Kim  Dong-Myung 《Ocean Science Journal》2019,54(4):559-571

Ocean Science Journal - Flushing time is a concept to show the characteristics of water exchange in the sea, and a longer flushing time generally translates as delayed water exchange and thus a...  相似文献   

Spatial autocorrelation and data uncertainty in the American Community Survey: a critique     

Paul H. Jung  Jean-Claude Thill  Michele Issel 《International journal of geographical information science》2019,33(6):1155-1175

ABSTRACT

We argue that the use of American Community Survey (ACS) data in spatial autocorrelation statistics without considering error margins is critically problematic. Public health and geographical research has been slow to recognize high data uncertainty of ACS estimates, even though ACS data are widely accepted data sources in neighborhood health studies and health policies. Detecting spatial autocorrelation patterns of health indicators on ACS data can be distorted to the point that scholars may have difficulty in perceiving the true pattern. We examine the statistical properties of spatial autocorrelation statistics of areal incidence rates based on ACS data. In a case study of teen birth rates in Mecklenburg County, North Carolina, in 2010, Global and Local Moran’s I statistics estimated on 5-year ACS estimates (2006–2010) are compared to ground truth rate estimates on actual counts of births certificate records and decennial-census data (2010). Detected spatial autocorrelation patterns are found to be significantly different between the two data sources so that actual spatial structures are misrepresented. We warn of the possibility of misjudgment of the reality and of policy failure and argue for new spatially explicit methods that mitigate the biasedness of statistical estimations imposed by the uncertainty of ACS data.  相似文献   

Numerical simulation of impact loads using a particle method     

B.-H. Lee  J.-C. Park  M.-H. Kim  S.-J. Jung  M.-C. Ryu  Y.-S. Kim 《Ocean Engineering》2010,37(2-3):164-173

The violent free-surface motions interacting with structures are investigated using the moving particle semi-implicit (MPS) method, which was originally proposed by Koshizuka and Oka (1996) for incompressible flow simulation. In the present numerical method, a more efficient algorithm for Lagrangian moving particles is used for solving various highly nonlinear free-surface problems without using the Eulerian approach or the grid system. Therefore, the convection terms and time derivatives in the Navier–Stokes equation can be calculated more directly without any numerical diffusion, instabilities, or topological failure. In particular, the MPS method is applied to the simulation of liquid-entry and slamming problems, such as wet-drop (liquid–liquid collision) tests in an LNG tank and slamming loads (solid–liquid collision) on rigid plates with various incident angles. The numerical results are in good agreement with available experimental data.  相似文献   

PIV measurements of hull wake behind a container ship model with varying loading condition     

Jung Yeop Lee  Sang Joon Lee 《Ocean Engineering》2009,36(5):377-385

Flow characteristics of the hull wake behind a container ship model were investigated under different loading conditions (design and ballast loadings) by employing the particle image velocimetry (PIV) technique. Measurements were made at four transverse locations and two longitudinal planes for three Reynolds numbers (Re) (=U₀Lpp/ν, where U₀ is the freestream velocity, Lpp is the length between two perpendiculars of the ship model and ν is the kinematic viscosity) of 5.08×10⁵, 7.60×10⁵, and 1.01×10⁶. It was observed that symmetric, large-scale, longitudinal counter-rotating vortices (with respect to centerline) of nearly the same strength were formed in the near wake. For the ballast-loading condition, the vortices appear at propeller plane below the propeller-boss. The vortex center exhibits a significant upward shift near the propeller-boss as the Reynolds number increase, and as the flow moves downstream. Under the design-loading condition, the vortices first appear at a further downstream location than that for the ballast-loading condition above the propeller-boss. This difference in the flow structure can significantly change the inflow conditions to the propeller blades, such as the streamwise mean velocity profiles and turbulence intensity distributions at the propeller plane. In particular, under the ballast-loading condition, asymmetric inflow may weaken the propulsion and cavitation performance of the marine propeller.  相似文献   

Towards multi-resolution global climate modeling with ECHAM6–FESOM. Part I: model formulation and mean climate     

D. Sidorenko  T. Rackow  T. Jung  T. Semmler  D. Barbi  S. Danilov  K. Dethloff  W. Dorn  K. Fieg  H. F. Goessling  D. Handorf  S. Harig  W. Hiller  S. Juricke  M. Losch  J. Schröter  D. V. Sein  Q. Wang 《Climate Dynamics》2015,44(3-4):757-780

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Naturalization of Landscaping Woody Plant,Magnolia obovata Potentially Invasive Species     

KWON Oh Jung  OH Choong Hyeon 《山地科学学报》2015,(1):30-38

Magnolia obovata, a tree species native to Japan, is a traditional landscaping tree that has also been introduced to various countries. M. obovata individuals have recently emerged in non-planting areas in Korea, prompting us to investigate its distribution by establishing Dosolsan in an urban forest of Daejeon City as the target site. In order to determine its naturalization, the study explored the status of population growth by examining the diameter at breast height of the individuals, and diameter diminution quotient was calculated. Cores of the trees were collected, and the age distribution was estimated by regression analysis. Reproduction possibility was analyzed by verifying the flowerblooming and fruit-bearing. Spontaneous colonization was investigated in the other potential sites which have different location and environment, respectively.The diameter distribution showed a reverse J-shaped curve, and the diminution quotient was ≥ 1.8. The population was composed of different generations,thus confirming the growth of the population. The distributed M. obovata grew and flowered normally,and followed a normal life cycle. The same phenomenon was observed in other planting areas,residual forests in urban or rural areas, alluvial islands, and mountain forests. The continuous spread of M. obovata in new ecosystems may be attributable to its long-term distribution by birds, relatively fast growth, and maturity time. Investigations on the naturalization and spread of M. obovata in Korea, as well as in various countries, are warranted.  相似文献   

Strategy for the meteorological and environmental airborne observations over the Korean Peninsula     

Chulkyu Lee  Ki-Ho Chang  Jae-Won Jung  Joo-Wan Cha  Young-Jean Choi  Kyungsik Kim 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(1):91-96

Aircraft campaigns for the meteorological and environmental research have been conducted in regional and global scales. The aircraft is increasingly considered as one of the best platforms to get the atmospheric three-dimensional information, especially over sea. We discuss the airborne observation plan and payloads designed for the aircraft campaigns over the Korean Peninsula. The main goals of the campaigns are to (i) conduct precipitation (snow) enhancement experiments with observations of the microphysical properties of clouds, dominantly in winter, (ii) monitor the severe weather generally in summer, (iii) characterize the climate change composition and the outflow of pollution from the Asian continent of the troposphere over the Korean Peninsula generally in spring or fall, and (iv) validate satellite and ground-based remote measurements of tropospheric composition generally in spring or fall.  相似文献   

Stability Assessment of a Pit Slope Under Blast Loading: A Case Study of Pasir Coal Mine     

D. Deb  K. N. R. Kaushik  B. H. Choi  C. H. Ryu  Y. B. Jung  C. Sunwoo 《Geotechnical and Geological Engineering》2011,29(4):419-429

In Pasir mine, coal seams and host rocks of varying thickness have been uniquely deposited with an average dip angle of 85°. The host rocks are weak and mainly composed of mudstone and sandstone comprising of 90–95% of the total pit volume. The thickness of coal seams and host rocks ranges from sub-metric to few tenths of meter. The overall safe pit slope angle was evaluated to be 27° for mining depth of 50–150 m. Several slopes failure incidents have occurred in the mine causing considerable disruption in production and monetary loss. It is envisaged that slope failures may be triggered due to blasting conducted in steeply dipping stratified deposit. In order to investigate the causes of slope failures, peak particle velocity (PPV) and accelerations at various locations from the blast site have been measured. In addition, finite element models of pit slope have been analyzed by applying static or gravity loading as well as blasting or dynamic loading. This paper elaborates the results of in situ measurements of ground vibration and numerical investigation and suggests possible causes of slope failures in Pasir mine.  相似文献