A simulation study for the logistics planning of a container terminal in view of SCM

This paper aims to apply a supply-chain modelling and its analysis framework to the supply chain in the port industry. The simulation approach serves two purposes: to model a supply-chain network in quantity approach and to evaluate its supply-chain performance based on proposed strategies. Through the modelling works to improve the performance, components of simulation model, such as input model, strategy model, operational policy model and performance model, in the port supply chain were identified. The effects of various strategies can guide the way to administrate the supply chain in the different objectives.     

DC Motor Current Control Algorithm Using Proportional-Integral LQT with Disturbance Observer

This paper proposes a DC motor current control algorithm using a proportional-integral linear quadratic tracking (LQT) controller with a disturbance observer for the electronic stability control (ESC) brake system. Previously researched algorithms related to current control using disturbance rejection are robust control, adaptive control, LQT, or proportional-integral disturbance observer (PI-DOB); each of them has both advantages and disadvantages. The proposed algorithm uses a disturbance observer in order to improve disturbance rejection performance while avoiding the drawbacks of high gain property. Additionally, the proposed algorithm adds integral control in order to improve performance in the low frequency bands. In order to assess the performance of the proposed algorithm, simulations and experiments are performed in the time and frequency domains to compare the proposed algorithm with different algorithms which are actually implemented into the ESC. The proposed algorithm shows good characteristics near the cut-off frequency, which can be confirmed clearly by the time domain results.     

Development of hydrogen-compressed natural gas blend engine for heavy duty vehicles

Natural gas fuel, as an alternative energy source of transportation, has been used widely since it has an advantage of low emission levels. However, new technologies are required in order to meet the reinforced emission regulations. For this purpose, research into the development of hydrogen-compressed natural gas (HCNG) blend engine was carried out to evaluate its feasibility and emission characteristics. The Engine Research Department at the Korea Institute of Machinery and Materials carried out a large number of tests based on various parameter changes that could affect the performance and emission of HCNG engine in different operating conditions. An earlier stage of the research project focused on the lean combustion of a HCNG engine for heavy duty vehicles to meet the EURO-VI standards. An 11-L/6-cylinder CNG engine was used for the test. The effects of the excess air ratio change were assessed based on various content ratios of hydrogen in the natural gas fuel. In the later part of the HCNG research, a stoichiometric mixture operation was suggested to meet reinforced emission regulation without requiring a De-NOx system. Additionally, an exhaust gas recirculation (EGR) system was introduced for the purpose of improving thermal efficiency and durability. The optimal operating conditions were selected to achieve the best thermal efficiency to meet the required emission levels. In this paper, we demonstrate that a HCNG engine can achieve a significant decrease in NOx emissions, as compared to that of a CNG engine, while meeting the requirements of the EURO-VI standards during a transient mode cycle test. EGR can suppress the weakness of stoichiometric mixture combustion strategy, such as the deterioration of the durability and thermal efficiency, while the emission level can be lowered with the use of a three-way catalyst. The possibility of further reduction of emissions and CO2 with EGR was evaluated to access practical application of a HCNG engine in the field. From that evaluation, the HCNG engine with stoichiometric mixture operation for heavy duty vehicles was developed. The emission levels of HCNG engine were 50 % lower when compared to the EURO-VI standards with a greater than 10 % decrease in CO₂ compared to that of a natural gas engine.     

Restructuring of the economy and its impacts on the Korean maritime industry

The Korean government has made many efforts to repair the damage done by the financial crisis since November 1997. The restructuring programmes for the Korean economy, including chaebols' (i.e. family-controlled conglomerates) restructuring, have impacted in many ways on the shipping, shipbuilding and port sectors. This is because major shipping lines, shipyards, and recent privatization and operation of container terminals have closely been related to chaebols. This paper is concerned with the impacts of the Korean financial crisis on the shipping, shipbuilding, and port sector, with restructuring of the economy and chaebols.     

A study of the bi-directional pedestrian flow characteristics at Hong Kong signalized crosswalk facilities

This paper investigates the bi-directional flow characteristics at signalized crosswalk facilities in Hong Kong. Pedestrian flow measurements were conducted at selected signalized crosswalks in Hong Kong urban area with and without the Light Rail Transit (LRT) railway tracks in the median of the carriageway. The pedestrian speed-flow functions for these crosswalk facilities were calibrated. The relationships between the walking speed at capacity and directional distribution of pedestrian flow (or flow ratio) are determined. The effects of different flow ratio on the effective capacity are also investigated. The bi-directional pedestrian flow effects on signalized crosswalk facilities with LRT tracks are found more significant than those without LRT tracks. The result could be used as a basis to improve the assessment of the crosswalk's capacity and to determine the design walking speeds under different flow ratios at signalized crosswalks in Hong Kong and in other Asian cities with similar environments.     

Optimal scheduling of block lifting in consideration of the minimization of traveling distance while unloaded and wire and shackle replacement of a gantry crane

Nowadays, shipyards are making every effort to efficiently manage their resources such as gantry cranes, transporters, and block stock yards. The scheduling of block lifting for a gantry crane has been manually performed by an expert shipyard manager for many years. Such a practice, however, can lead to an undesirably long time to produce scheduling plans. In addition, the quality of the scheduling plans may not be optimal. To improve the overall process, a block lifting scheduling system for a gantry crane was developed in this study by using optimization techniques. A block lifting scheduling problem was first formulated as a multiobjective optimization problem. For a gantry crane, minimization of the traveling distance while unloaded and wire and shackle replacement between block lifting was considered. An optimization algorithm based on the genetic algorithm was then proposed and implemented so as to solve the problem. To evaluate the efficiency and applicability of the developed system, the system was applied to an actual block lifting scheduling problem in a shipyard. Compared to results achieved by manual scheduling by an expert manager, the results of this work show that blocks can be more efficiently lifted by a gantry crane when the developed system is applied.     

Computational investigation of cavitation on a semi-spade rudder

This article examines noncavitating and cavitating flow fields around a semi-spade rudder in the ship wake and propeller slipstream based on a computational method. The article seeks to explain the erosion that can occur around the gap due to cavitation; such erosion has been reported to occur while a ship is at sea. Another area of research is the effect of the gap size and shape. The effects of erosion-evading devices such as elongated gap edges, an increased edge radius, flow control projections, and vertical and horizontal guide plates were also studied.     

A process-centric ship design management framework

As the concept of concurrent engineering has emerged along with support for optimization techniques, lots of endeavors have been made to apply optimization techniques to real design problems for holistic decision-making. Even if the range of design problems to which optimization is applicable has been extended, most ship designs use an iterative and manual approach due to the difficulties of seamless integration of all related design activities. This paper proposes a process-centric management framework for the preliminary ship design process depending on these approaches. Requirements for the framework are generated based on the features of the ship design process first. The proposed framework consists of both process scheduling and process management parts. Each of these modules is divided into submodules, and the modules and their interactions are elaborated to reflect actual design practice. The designed framework is embodied within a workflow system and its usefulness examined through a pilot project.     

Research trends and agenda on the Belt and Road (B&R) initiative with a focus on maritime transport

The ‘Silk Road Economic Belt and the 21st-Century Maritime Silk Road’ (collectively known as Belt and Road, B&R) has been initiated by the Chinese government in 2013. The B&R is increasingly becoming a focal point for socio-economic–political interests because of its likely impact on land and sea transport and maritime logistics. The aims of this study were threefold: first, to provide an overview on the B&R, focusing on its key structural elements, such as transport corridors, city clusters, dry ports, infrastructure, zoning, and area development; second, to identify the expected impacts of the B&R on trade and implications on structural changes in transportation systems, port networks, and international logistics. Finally, to discuss major research trends and setting up of research agenda which will contribute to enriching the existing literature and shaping the global trade operations and drive economic growth in the context of the B&R.     

Internal tidal currents in the Gaoping (Kaoping) Submarine Canyon

Data from five separate field experiments during 2000–2006 were used to study the internal tidal flow patterns in the Gaoping (formerly spelled Kaoping) Submarine Canyon. The internal tides are large with maximum interface displacements of about 200 m and maximum velocities of over 100cm/s. They are characterized by a first-mode velocity and density structure with zero crossing at about 100 m depth. In the lower layer, the currents increase with increasing depth. The density interface and the along-channel velocity are approximately 90° out-of-phase, suggesting a predominant standing wave pattern. However, partial reflection is indicated as there is a consistent phase advance between sea level and density interface along the canyon axis.