• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.4
• /
• pp.470-477
• /
• 2000

The states of control loops in existing actual systems are changed according to time varying conditions of controllest process and other system components. Adjusting control parameters properly at site which is performed generally by Ziegler & Nichols mthod is important for safe and efficient operation, but the method may require much time to adjust and not easy to inexperienced engineers. This study is aimed to propose more handy method to adjust control parameters by plotting operating conditions on the space of adjusting parameters. One loop of model control system without perturbation condition has been adopted and its stability limit was plotted on the coordinates of Gain and Integral time which was acquired after analyzing Nyquist diagrams and time domain responses. The result showed that the sets of adjusting parameters according to critical stability and proper stability could be acquired reasonably through both responses and the curves on parameter space revealed available patterns for the purpose of easy maintenance of control characteristics.

• Steel and Composite Structures
• /
• v.52 no.5
• /
• pp.525-541
• /
• 2024

This study uses the state-space approach to study the bending behavior of Levy-type functionally graded (FG) plates sandwiched between two piezoelectric layers. The coupled governing equations are obtained using Hamilton's principle and Maxwell's equation based on the efficient four-variable refined plate theory. The partial differential equations (PDEs) are converted using Levy's solution technique to ordinary differential equations (ODEs). In the context of the state-space method, the higher-order ODEs are simplified to a system of first-order equations and then solved. The results are compared with those reported in available references and those obtained from Abaqus FE simulations, and good agreements between results confirm the accuracy and efficiency of the approach. Also, the effect of different parameters such as power-law index, aspect ratio, type of boundary conditions, thickness-to-side ratio, and piezoelectric thickness are studied.

• 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.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.12
• /
• pp.3840-3842
• /
• 2013

• Tribology and Lubricants
• /
• v.22 no.4
• /
• pp.218-224
• /
• 2006

The sludge oils were produced necessarily in the ships operation, so that it will be the best way to manage the sludge oils inside ship itself from a viewpoint of the prevention of marine oil pollution. The ultra-sonic breaking system which recycle the sludge oil from ship into usable oil to be brunt is recognized as a most possible recycling device. In this regards, the purpose of this study is to examine erosion damage,on the SS400 specimen by cavitation and the effect of impact pressure generated from the demolition of the cavity of ultrasonic vibration in the marine sludge oil environment.. The erosion damage of specimen was investigated mainly on weight loss, weight loss rate and maximum erosion rate with variation of the oil temperature as well as the change of space between transducer hem and specimen. The experimental results showed that as the space between ultrasonic vibrator horn and specimen disk increased, the weight loss and weight loss rate decreased and the values were larger in SFO than in SLO. The experimental results can be useful to the development of sludge oil disposing systems and to consider a countermeasure for the prevention of erosion damages by cavitation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2002.05a
• /
• pp.231-236
• /
• 2002

By using the infinite dimensional optimization[Jang and Kinoshita(2000)]. which is based on the Hilbert space theory, optimal marine propellers are studied. The mathematical uniqueness for the optimized propeller is shown in this study. As a numerical example, the MAU type propeller is considered and used as the initial guess for the optimization method. The numerical results for an optimal marine propeller is illustrated for the pitch distribution.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2012.06a
• /
• pp.269-269
• /
• 2012

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.2
• /
• pp.166-172
• /
• 2007

The flow around a rotating circular cylinder near a plane wall is investigated by the measurement of the lift acting on the cylinder and by the flow visualization using the hydrogen bubble technique in the circulating water tank. The experimental parameters are the rotating direction of the cylinder. the space ratios $H/D(H/D=0.05{\sim}0.5)$ between cylinder and plane wall and the velocity ratios ${\alpha}({\alpha}=0{\sim}{\pm}2.0)$. In the case of clockwise, the lift on the rotating circular cylinder was increased with the reduction of the space ratios and with the velocity ratios, the upper separation point was more shifted in the rotating direction with them. In the case of anticlockwise, the absolute value of the lift on the rotating circular cylinder was increased with increasing the space ratios and the velocity ratios. the lower separation point was more shifted in the rotating direction with them.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.3
• /
• pp.235-242
• /
• 2007

This paper discusses dynamic characteristics of a urea-SCR (Selective Catalytic Reduction) system. The urea flow rate to improve NOx conversion efficiency is generally determined by parameters such as catalyst temperature and space velocity. The urea-SCR system was tested in the various engine operating conditions governing the raw NOx emission levels, space velocity. and SCR catalyst temperature. These experiments include cold-transients to determine catalyst light-off temperature and urea flow rate transients. Likewise. ammonia storage dynamics was also investigated. The cold-transient results indicate the light-off temperature of the catalysts used in these experiments was $200-220^{\circ}C$. The ammonia storage and urea flow rate transients all indicate very slow dynamics (on the order of seconds) which presents control challenges for mobile applications. The results presented in this paper should provide an excellent starting point in developing a functional in-vehicle urea-SCR system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.27 no.1
• /
• pp.91-99
• /
• 2003

This paper describes the development of a pc-based machinery space simulator for training and research, relevant to STCW-95. The detailed mathematical modelling process for the actual machinery is discussed and a method to perform effective education and training for the simulator is suggested. The method includes scenario, procedure, exercise and evaluation. The procedure guides the trainee through a sequence of steps designed to meet a specific goal, showing the trainee what must be done and explaining why The exercise enhances understanding for efficient engine management and enable user to perform research for the machinery. The evaluation shows exercise results and feeds back to instructor how to guide the under-performed trainee.