In marine engineering, it is prone to encounter free surface flow problems. Typically, a boat moving on water causes nonlinear free surface flows accompanied by spray. A high-speed boat, in particular, experiences considerable resistance due to the spray, and some high-speed boats such as seaplanes and hovercrafts suffer great damage in their propulsion systems. Thus, predicting nonlinear free surface flow is an important issue for developing high-speed boats with high performance.

For the simulation of free surface flows, some computational fluid dynamics approaches called mesh-based method have been proposed. These methods are suitable for the flow of low-speed boats but not suitable for high-speed boats.

Other approaches called mesh-free method or particle method have been proposed for free surface flows. Moving particle semi-implicit (MPS), smoothed particle hydrodynamics (SPH) and particle finite element method (PFEM) are typical mesh-free methods widely used for nonlinear free surface flows. In many studies, mesh-free methods have been applied successfully to lots of problems in the marine engineering field.

Pak Chol Jun, a researcher at the Faculty of Shipbuilding and Ocean Engineering, has proposed an improved MPS method with some modifications for simulating the flow around a moving body. To improve the original MPS method, he proposed the intermediate velocity of wall particles, Laplacian compensation in the domain close to the boundary, a technique to prevent fluid particles from penetrating the wall boundary, and a handling technique for the open boundary.

He applied the improved MPS method to hydrostatic pressure and sloshing problems to validate its performance. The comparison of the numerical results with the analytical results and experimental data showed that Laplacian compensation remarkably enhances the accuracy of MPS method.

Automatic Guided Vehicles (AGVs) are material handling equipment traveling on a network guide path. AGVs can be interfaced with other equipment for production and storage. Increasing the efficiency of automatic guided vehicle (AGV) scheduling is one of the important issues to improve the productivity of manufacturing enterprises.

Ri Il Chol, a researcher at the Faculty of Automation Engineering, has established a multi-objective mathematical model for scheduling multi-load AGVs carrying production materials and cutting tool consumables.

The objective function includes three objectives: the total moving distance of AGVs, the standard deviation of AGV workload and the standard deviation of the difference between the latest delivery time and the predicted time of tasks. Then, he implemented the assignment and ordering of tasks performed by AGV by implementing neighborhood search strategy using an improved harmony search algorithm.

He has applied the proposed harmony search algorithm to a virtual manufacturing enterprise to evaluate its performance.

The computational results show that the proposed harmony search algorithm outperforms the genetic algorithm.

Rod coal briquette is a kind of porous material consisting of solid coal particles, liquid phase moisture, stream and air, and study of drying process of coal briquette is that of porous material.

Most researchers proposed some mathematical models of drying inside porous material by convective heat. They are classified into diffusion model, theory model based on osmosis evaporation, and models based on Whitaker’s continuum theory and non-equilibrium thermodynamics.

Study on heat and mass transfer in porous material was conducted for a long period and it developed from the basic theory of heat and moisture transfer mechanism into the modern comprehensive and logical scientific theory. However, most studies were focused on the drying of wood, grain and paper, and not on rod coal briquette.

Pak Kyong Il, a researcher at the Faculty of Metal Engineering, designed a tunnel-type dryer for reducing coal consumption while reducing the cracking of briquettes and increasing their strength by improving the thermal working state of a tunnel dryer with low recovery and high coal consumption required for drying.

Compared to the conventional dryers, the newly-designed one has many advantages. First, drying time per batch is reduced by 4h from 24h to 20h. Second, 48kg of coal is saved for drying a ton of coal briquettes. Third, cracking rate is reduced by 23%.

In addition, cold compressive strength and hot compressive strength, and hot abrasive strength are raised by 10-11% and 4-5%, respectively, to improve the quality of briquettes used for iron production in small blast furnaces.