• Journal of Korean Society of Steel Construction
• /
• v.29 no.1
• /
• pp.89-98
• /
• 2017

The offshore plant structure has been transported to the site by barge because it is hard to manufacture in site. When the structure was transported on the sea, offshore plant structures and connection were experienced repetitive submarine load. For this reason, it was known for that the axial force of high-strength bolted connection was declined. Therefore, in this study, high-strength bolted connection was evaluated the shear fatigue performance under longtime fatigue load during marine transport. The experimental variables were selected intial axial force, surface type, and bolt type because they ar important factors in the change of axial force of bolts. As a experimental results of considering various variables, the variation of axial force showed within 1%. Therefore, the high-strength bolted connection was verified structural safety under longtime fatigue load.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.6
• /
• pp.637-645
• /
• 2018

This study analyzes the problem of lack of anchorage caused by some anchorage closed and suggests ways to improve Masan anchorage. For this, we established the evaluation criteria, and analysed the anchorage operating rate during 5 years after estimating the capacity of barge, and suggested improvement plan after appropriateness assessment of anchorage capacity, finally verified the anchorage improvement plan. As a result of study, it is analyzed that the Masan A-2, A-4, A-6 anchorage needs to expand the anchorage due to excess the anchorage assessment criteria of 60 %. So, in order to improve the Masan anchorage, we suggested the improvement plan that extended 1.8 times by the group designated anchorage, according to integrating the A-2, A-4, A-6 anchorage and anchorage dwell time and ship type. And, the result of verification improvement plan, it is analyzed that meet the assessment criteria since decreasing the anchorage operating rate by 1/2 compared to the existing one, does not act as a risk factor in terms of maritime traffic.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.14 no.2
• /
• pp.163-168
• /
• 2008

Ship detection from satellite remote sensing is a crucial application for global monitoring for the purpose of protecting the marine environment and ensuring marine security. It permits to monitor sea traffic including fisheries, and to associate ships with oil discharge. An automatic ship detection approach for RADARSAT Fine Synthetic Aperture Radar (SAR) image is described and assessed using in situ ship validation information collected during field experiments conducted on August 6, 2004. Ship detection algorithms developed here consist of five stages: calibration, land masking, prescreening, point positioning, and discrimination. The fine image was acquired of Ulsan Port, located in southeast Korea, and during the acquisition, wind speeds between 0 m/s and 0.4 m/s were reported. The detection approach is applied to anchoring ships in the anchorage area of the port and its results are compared with validation data based on Vessel Traffic Service (VTS) radar. Our analysis for anchoring ships, above 68 m in length (LOA), indicates a 100% ship detection rate for the RADARSAT single beam mode. It is shown that the ship detection performance of SAR for smaller ships like barge could be higher than the land-based radar. The proposed method is also applied to estimate the ship's dimensions of length and breadth from SAR radar cross section(RCS), but those values were comparatively higher than the actual sizes because of layover and shadow effects of SAR.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.18 no.1
• /
• pp.22-28
• /
• 2015

The design on a riser in 1MW OTEC system is performed. The minimum diameter of the riser is decided depending on intake quantity of deep-sea water to supply an OTEC cycle. An applicable pipe material is selected from analyzing the properties of commercial pipes. The selected HDPE pipe with the low density and strength is reinforced with a lumped block attached at the end of and wire ropes along the riser. A lumped block, connected to a floating structure by wire ropes, with 25% and 50% weight of a GFRP riser is designed to be attached the end of a riser. The structural safety of the HDPE riser with wire rope supporting axial loads induced by a lumped block is analyzed under the harsh ocean environmental condition near Hawaii ocean with the numerical method. The final dimension of the riser and accessories is determined considering the economic point of view. The designed riser will be applicable to the construction of the 1 MW OTEC pilot plant.