• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.7
• /
• pp.509-516
• /
• 2014

This paper proposes estimation model of uncertainty in vibration measurement of shipboard equipment and analyzes the result of uncertainty estimation. Vibration of shipboard equipments affects underwater radiated noise that is important performance related to stealth of the naval vessel. Acceptance testing for shipboard equipment is required to guarantee the stealth performance of naval vessel. In measuring, detailed uncertainty estimation is essential to improve measuring reliability. Acceptance testing result of structure-borne noise and vibration is used to analyze uncertainty in vibration measurement of shipboard equipment.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.22 no.1
• /
• pp.42-48
• /
• 2019

Since the underwater telephone was sold in a short time, there are few repair equipments. And equipment is difficult to locate fault. Equipment with transducers must be inspected underwater, and a relative naval vessels is required to perform an operational check. So we developed a tester device to test the transmission card through the spectrum and transmission power, and to develop a device that can conduct operational tests on land. Therefore, the development of the tester reduces the incidence of naval vessels and contributes to the development of domestic underwater communication test equipment.

• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.5 s.149
• /
• pp.611-618
• /
• 2006

Recently, cryogenic butterfly valves for LNG carriers are actively developed by ship equipment companies. The dual core structure unlike usual butterfly valve has both translation and gyration motions of the disk of the valve assembly. Especially, the ship equipment companies can not have overcome 2D design method; in addition, even though 2 years of development has passed, the drawing cannot be secured. In this research, for the cryogenic butterfly valves and the product design, 3D design method was introduced and DMU(Digital Mockup) was applied to complement the problems in 2D design and investigate application possibility of 3D design method.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.3
• /
• pp.212-219
• /
• 2014

As subsea production has been revived up, the demand of subsea equipment has also been increased. Among the equipment, subsea tree plays a major role in safety. The tubing hanger is one of the most important components in subsea tree. In this study structural reliability analysis on dual bore tubing hanger of subsea tree is performed. The target reliability which is introduced in ISO regulation is used for judging whether tubing hanger is safe or not. The considered loads are working pressure, working temperature and suspended tubing weight. Thermal-stress analysis on tubing hanger is performed and kriging model is created based on the results of FEM analysis. According to von Mises criterion, limit state equation can be estimated. Reliability analysis is performed by using level 2 method and the result is verified by that of Monte Carlo Simulation. For finding most probable failure point, enhanced HL-RF method is adopted. Because the reliability of model doesn't reach target reliability, an improvement measure should be considered. Thus, it is suggested to change the material of tubing hanger main body to AISI 4140.

• Journal of the Society of Naval Architects of Korea
• /
• v.52 no.3
• /
• pp.275-281
• /
• 2015

Mounts for shipboard equipment in naval ships play an important role for vibration and shock suppression. New large-capacity resilient mounts, SDR-D30 and SDR-D45, have been developed. This paper involves performance tests for the mount which have maximum load of 30 kN and 45 kN, respectively. The performance tests have been carried out for several mounts based on military standards, such as MIL-M-19863D(SH), MIL-M-21693C(SH), MIL-M-17508F(SH), and MIL-S-901D(NAVY). The test items consist of deflection at upper rate load test, dynamic stiffness, uniformity, static load-deflection(axial, transverse and longitudinal), drift test, fatigue test, and shock test. From these performance tests, it is confirmed that the two mounts have good performances based on military standards.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.4 no.4
• /
• pp.362-373
• /
• 2012

The ship recycling industry is growing rapidly. It is estimated that the International Maritime Organization's (IMO) decision to phase-out single hull tankers by 2015 will result in hundreds of ships requiring disposal. At present, the ship recycling industry is predominantly based in South Asia. Due to the bad practice of current scrapping procedure, the paper will highlight the harm occurring to health, safety and environment. The efforts of the Marine Environment Protection Committee (MEPC) which led to the signing of the Hong Kong International Convention are also reviewed. The criteria and standards required to reduce the risk and damage to the environment are discussed and a proposed plan for the safe scrapping of ships is then presented. A technological and economic study for the ship recycling in Egypt is carried out as a case study. This includes the ship recycling facility size and layout. The equipment and staff required to operate the facility are also evaluated. A cost analysis is then carried out. This includes site development, human resources, machineries and equipment. A fuzzy logic approach is used to assess the benefits of the ship breaking yard. The use of the fuzzy logic approach is found suitable to make decisions for the ship breaking industry. Based on given constraints, the proposed model has proved capable of assessing the profit and the internal rate of return.

• Journal of the Society of Naval Architects of Korea
• /
• v.45 no.3
• /
• pp.288-295
• /
• 2008

Passive-type control devices such as resilient mounts and wire rope isolators are generally used for protecting the shipboard equipment from shock loading and for suppressing the mechanical vibration of the equipment in naval ships. To improve the performance of the control device, a new hybrid mount is under development in this study. This mount consists of a passive-type rubber element and an active-type piezo-stack element. It can be expected that the mount has enhanced performance of about 20 dB or more with respect to transmissibility through a series of performance tests of prototype mount.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.3
• /
• pp.100-107
• /
• 2015

Recently as the manufacturers want competitiveness in dynamically changing environment, they are trying a lot of efforts to be efficient with their production systems, which may be achieved by diminishing unplanned operation stops. The operation stops and maintenance cost are known to be significantly decreased by adopting proper maintenance strategy. Therefore, the manufacturers were more getting interested in scheduling of exact maintenance scheduling to keep smooth operation and prevent unexpected stops. In this paper, we proposedan integrated maintenance approach in injection molding manufacturing line. It consists of predictive and preventive maintenance approach. The predictive maintenance uses the statistical process control technique with the real-time data and the preventive maintenance is based on the checking period of machine components or equipment. For the predictive maintenance approach, firstly, we identified components or equipment that are required maintenance, and then machine parameters that are related with the identified components or equipment. Second, we performed regression analysis to select the machine parameters that affect the quality of the manufactured products and are significant to the quality of the products. By this analysis, we can exclude the insignificant parameters from monitoring parameters and focus on the significant parameters. Third, we developed the statistical prediction models for the selected machine parameters. Current models include regression, exponential smoothing and so on. We used these models to decide abnormal patternand to schedule maintenance. Finally, for other components or equipment which is not covered by predictive approach, we adoptedpreventive maintenance approach. To show feasibility we developed an integrated maintenance support system in LabView Watchdog Agent and SQL Server environment and validated our proposed methodology with experimental data.

• Journal of the Society of Naval Architects of Korea
• /
• v.57 no.4
• /
• pp.207-212
• /
• 2020

To decide a separation distance of the redundant vital equipment in a naval ship, the damage radius due to an aerial explosion should be estimated. In this research, a simplified formula for the damage radius has been developed by using existing empirical formulae for reflected shock pressure and shock lethality value of equipment. As a numerical example, the damage radius for a typical pump aboard a naval ship has been calculated by the developed formula and compared with the results calculated by Measure of Total Integrated Ship Survivability (MOTISS) which is one of survivability analysis codes verified, validated and accredited by the US Navy. Also, comparison with the results calculated by existing other simplified formulae has been made.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.7
• /
• pp.784-791
• /
• 2013

Recent advanced IT made layout design fast and accurate by using algorithms. Layout design should be determined by considering the position of equipment with satisfying various space constraints and its component works with optimum performance. Especially, engine room layout design is performed with mother ship data, theoretical optimal solution, design requirements and several design constraints in initial design stage. Piping design is affected by position of equipment seriously. Piping design depends on experience of designer. And also piping designer should consider correlation of equipment and efficiency of space. In this study, space evaluation method has been used to evaluate efficiency of space. And also this study suggested object function for optimal piping route, Average Reservation Index(ARI), Estimated Piping Productivity(EPP) and with modified space evaluation method. In this study, optimum pipe routing system has been developed to reflect automated piping route with space efficiency and experience of piping designer. Engine room is applied to the design of the piping in order to confirm validity of the developed system.