• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.4
• /
• pp.372-379
• /
• 2023

International oil prices are expected to increase from $85 a barrel this year to up to $100 a barrel in the second half of the year; this is likely to increase orders for offshore plants in the global market. One main characteristic of offshore plants is that a large helideck is located on the top side, and aluminum alloys are used as the basic material of the structure for weight reduction and corrosion resistance. Shipowners are increasing the size of helicopters to quickly evacuate lives in the event of an emergency, and the safety use load of devices that can stably secure helicopters to the deck is also required to increase. Owing to the nature of the aluminum material, the structural strength caused by welding is greatly reduced; therefore, the fixing device must be designed by embedding it in the deck and fixing it with bolts. In this study, a model applying aluminum alloy 6082-T6 was developed to develop a helicopter fastening device that can be used for large helidecks (diameter = 28 m). The developed item was verified through nonlinear structural strength calculation to satisfy the load used for the actual fastening condition. The load condition with a 45° showed a lower ultimate strength than the 90° case owing to local plastic collapse. The nonlinear structural collapse behavior showed a result similar to that of the experimental test. The main contents derived from this study are considered to be reference materials when evaluating the structural strength of similar aluminum equipment.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.1
• /
• pp.172-178
• /
• 2021

In the ship repair market, interest in maintenance and repair is steadily increasing due to the reinforcement of prevention of environmental pollution caused by ships and the reinforcement of safety standards for ship structures. By reflecting this effect, the number of requests for repairs by foreign shipping companies increases to repair shipbuilders in the Southwest Sea. However, because most of the repair shipbuilders in the southwestern area are small and medium-sized companies, it is difficult to lead to the integrated synergy effect of the repair shipbuilding companies. Moreover, the infrastructure is not integrated; hence, using the infrastructure jointly is a challenge, which acts as an obstacle to the activation of the repair shipbuilding industry. Floating docks are indispensable to operating the repair shipbuilding business; in addition, most of them are operated through renovation/repair after importing aging caisson docks from overseas. However, their service life is more than 30 years; additionally, there is no structure inspection standard. Therefore, it is vulnerable to the safety field. In this study, the finite element analysis program of ANSYS was used to evaluate the structural safety of the modified caisson dock and obtain additional structural reinforcement schemes to solve the derived problems. For the floating docks, there are classification regulations; however, concerning structural strength, the regulations are insufficient, and the applicability is inferior. These insufficient evaluation areas were supplemented through a detailed structural FE-analysis. The reinforcement plan was decided by reinforcing the pontoon deck and reinforcement of the side tank, considering the characteristics of the repair shipyard condition. The final plan was selected to reinforce the side wing tank through the structural analysis of the decision; in addition, the actual structure was fabricated to reflect the reinforcement plan. Our results can be used as reference data for improving the structural strength of similar facilities; we believe that the optimal solution can be found quickly if this method is used during renovation/repair.

• Journal of Animal Environmental Science
• /
• v.15 no.3
• /
• pp.251-262
• /
• 2009

In this research dairy cattle barn facilities what are 4,198 houses hold over 50 heads were surveyed by scale and province. Full-time farms hold over 50 heads breed total 344,514 heads. Each of Farms holds 50 to 99 heads were 79.8 percent and breed average 82.1 heads. Dairy cattle barns were constructed september 1995 averagely. Each of barns have $1,740.0\;m^2$ scale. The construction type of dairy cattle barn was almost litter barn type 84.0%, freestyle type 5.1%, mooring+litter ground type 17.3% and other types 4.4%. The litter barn type was popular in small farms. But in large farms, freestyle type was popular than small farms. The construction type of dairy cattle barn was almost litter barn type 84.0%, freestyle type 5.1%, moohng+ltter ground type 17.3% and other types 4.4%. Type of dairy cattle robotic milking system was pipeline 41.5%, herringbone 22.8% and tandem 35.8%. The pipeline type was popular in small farms which have 50~99 heads. But in large farms which have over 200 heads, tandem type was popular than small farms. Proportion of floor type of dairy cattle barn was almost litter type 94.9%. Scraper type was popular in large farms than in small farms. Proportion of roof type of dairy cattle barn was slate 32.5%, vinyl 16.3%, sunlight 11.1%, panel 10.9, zinc plate 8.8 and steel plate 8.3%. Roof type was lots of slate type before 1995. But vinyl type is increasing after 1995. Proportion of wall type of dairy cattle barn was almost open type 83.3% and winch-curtain 26.8%. Utilization period of dairy cattle barn was 9.2 years about milker, 7.9 years about automatic feeder, 9.2 years about waterer and 10.4 years about electric facilities. In this results, there were lots of improvements about automatic feeder.