Ultimate load capacities of mooring bollards and hull foundation structures     

Sang-Rai Cho  Joonmo Choung  Chang-Min Oh  Kang-Su Lee  Jung-Yeob Kim 《Ocean Engineering》2010,37(8-9):770-776

CSRs (Common Structural Rules for bulker and tanker), which came into effect in 2006, invoke the concept of the ultimate strength of hull girders. While numerous studies associated with the ultimate capacities regarding global hull girders and stiffened panels have been carried out, there are few application cases of the ultimate strengths for deck machineries and their supporting structures. In the present study, nonlinear finite element analyses have been performed to obtain ultimate capacities for a size 450 DIN type bollard including hull foundation structures for which elastic strength assessments based on allowable stress analyses were jointly carried out by a Mooring Fitting SWL Standardization Committee consisting of four major Korean shipbuilders (DSME, HHI, HHIC, and SHI) in 2003. The plastic hardening property is identified from a comparison of the results of ultimate strength simulations and a bollard tension tests performed by the committee. It is assumed that the ultimate load is the corresponding load point when the deformation slope of the bollard column reaches the critical slip angle. It is concluded that the reinforcements appear to be effective with respect to the allowable stress criterion, but are not substantially effective from the point of view of ultimate capacities. In other words, structural reinforcements based on allowable stress analyses may noticeably increase production costs, but do not remarkably raise the ultimate capacities.  相似文献   

Experiments on vision guided docking of an autonomous underwater vehicle using one camera   总被引：1，自引：0，他引：1  

Jin-Yeong Park  Bong-huan Jun  Junho Oh 《Ocean Engineering》2009,36(1):48-61

This paper introduces an underwater docking procedure for the test-bed autonomous underwater vehicle (AUV) platform called ISiMI using one charge-coupled device (CCD) camera. The AUV is optically guided by lights mounted around the entrance of a docking station and a vision system consisting of a CCD camera and a frame grabber in the AUV. This paper presents an image processing procedure to identify the dock by discriminating between light images, and proposes a final approach algorithm based on the vision guidance. A signal processing technique to remove noise on the defused grabbed light images is introduced, and a two-stage final approach for stable docking at the terminal instant is suggested. A vision-guidance controller was designed with conventional PID controllers for the vertical plane and the horizontal plane. Experiments were conducted to demonstrate the effectiveness of the vision-guided docking system of the AUV.  相似文献   

A preliminary study of natural environmental change and its impact on early Late Paleolithic people in the northeast central Korean Peninsula during Marine Istope Stage 3 (40–30k cal a bp)     

Sangheon Yi  Chang-Gyun Han  Keun-Chang Oh  In Sun Seo  Dongwook Kim  Jaeyoung Lee  Min Han  Hanwoo Choi  Jaesoo Lim  Sujeong Park  Chang-Pyo Jun  Taesop Cho 《第四纪科学杂志》2022,37(1):100-113

We comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi-proxy analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp ) in the early Late Paleolithic. The palynoflora consisted of pollen and non-pollen palynomorphs. Under the air-circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad-leaved forest with an understory of pteridophytes flourished around the north-east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ¹⁸O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food.  相似文献