• Journal of Navigation and Port Research
• /
• v.38 no.6
• /
• pp.567-575
• /
• 2014

In recent times, an obvious strategy in liner shipping markets that has come to the fore is slow steaming. Nowadays, most liner shipping companies have decelerated the voyage speed to 15-18 knots on major routes, and some leading liner shipping companies have a plan to reduce it to below 15 knots. Slow steaming is helpful in reducing the operating cost and the amount of greenhouse-gas emissions on a single vessel with lower fuel consumption. However, it also creates various negative effects such as the opportunity cost, additional fixed costs and an in-transit inventory cost on a loop. Hence, the net operating cost on a loop is changing dynamically due to the changes of voyage speed based on various slow steaming effects. The aim of this study is to analyze the slow steaming effects in the liner shipping, and to find the best voyage speed that minimizes the operating cost on a loop. Moreover, this study suggests the recommendable strategy for liner shipping companies. To achieve the aim of this study, a simulation model has been designed using System Dynamics.

• Journal of Navigation and Port Research
• /
• v.48 no.2
• /
• pp.97-103
• /
• 2024

As there is growing concern about the environmental impact of greenhouse gas emissions from ships, the International Maritime Organization (IMO) has introduced several regulations targeting reductions in carbon dioxide emissions of 50% by 2050. This study pays particular attention to the carbon intensity indicator (CII) and investigates the impact of slow steaming, one of the short-term measures in the regulation, on containership operations. To this end, a dataset of 8 containerships with various ages and sizes was collected. Based on operation data in 2021, the CII ratings of the containerships were estimated in the business-as-usual scenario for the 2023-2030 period. Then, the speed reductions required to keep the minimum CII rating were calculated for individual containerships. Finally, working day losses resulting from the speed reductions were calculated. The findings in this study were threefold. First, it was found that containerships will undergo degradation in the CII rating every 3 or 4 years without slow steaming. Second, a speed reduction of 2 knots between 2023 and 2030 is required to keep the minimum CII rating. Finally, speed reductions result in the loss of as many as 6 or 7 working days per year.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.6
• /
• pp.411-417
• /
• 2015

The shipping and shipbuilding industries have had business difficulties since the implementation of regulations on the CO₂ emissions from ships by IMO and the occurrence of the global financial crisis in 2008. Under this global recession, most shipping firms have started to operate their fleets at slow steaming rates with the goal of improving the profit ratio per transported unit. This study analyzed the resistance performance of a 6,800 TEU container ship corresponding to its trim variation with slow steaming, compared with that at its original design speed. Two different grid systems were used for the numerical calculation, one that considered the free surface allowing the capture of the dynamic trim and one that did not. This made it possible to clearly classify each resistance component to provide useful information to hull-form designers. In addition, a form factor assumption method using CFD was used for a reasonable effective power prediction in compliance with the 1978 ITTC performance prediction method. It was found that the total resistance of a 6,800 TEU container ship was reduced by 2.6% in the case of a 1-m trim at the bow at 18 kn.

• Journal of the Korean Institute of Navigation
• /
• v.15 no.4
• /
• pp.27-39
• /
• 1991

One practical method has already been proposed for predicting the characteristics of ship manoeuvring motions at relatively high advance speed [19]. Howeverf, this method can hardly be applied to motions of ships in starting, stopping, backing and slow steaming conditions, even though such extensive motions are of vital importance from a safety point of view particularly in harbour areas. The method presented here aims at predicting the characteristics of ship manoeuvring at low advance speed, which covers starting, stopping, backing and slow steaming conditions. The force mathematical models at large angles of incidence to the hull as well as under the wide range of propeller operations are formulated. Simulations of various manoeuvres at low advance speed are carried out for two types of merchant ship, I.e. a LNGC and a VLCC. Comparisons between simulations and corresponding full-scale measurements [10], [15] or free-running model tests [6],[10] provide a first verification of the proposed mathematical models.

• Journal of the Society of Naval Architects of Korea
• /
• v.29 no.3
• /
• pp.90-101
• /
• 1992

Some practical methods have already been proposed for predicting the characteristics of ship manoeuvring motions at relatively high advance speed. However, these methods can hardly be applied to motions of ships in starting, stoppint, backing and slow steaming conditions, even though such extensive motions are of vital importance from a safety point of view particularly in harbour areas. The method presented here aims at predicting the characteristics of ship manoeuvring at low advance speed, which covers starting, stopping, backing and slow steaming conditions. The force mathematical models at large angles of incidence to the hull as well as under the tilde range of propeller operations are formulated. Simulations of various manoeuvres at low advance speed are carried out for two types of merchant ship, i.e. a LNGC and a VLCC. Comparisons between simulations and corresponding full-scale measurements or free-running model tests provide a first verification of the proposed mathematical models.

• Journal of Pharmacopuncture
• /
• v.11 no.2
• /
• pp.87-95
• /
• 2008

Objectives The aim of this experiment is to provide an differentiation of ginseng, red ginseng, cultivated wild ginseng(CWG), and red wild ginseng(RWG) through component analysis using HPLC(High Performance Liquid Chromatography, hereafter HPLC). Methods Comparative analyses of ginsenoside $Rg_3$, ginsenoside $Rh_2$, and ginsenosides $Rb_1$ and $Rg_1$ of various ginsengs were conducted using HPLC. Results 1. CWG was relatively heat-resistant and showed slow change in color during the process of steaming and drying, compared to cultivated ginseng. 2. Ginsenoside $Rg_3$ was not detected in cultivated ginseng and CWG, whereas it was high in red ginseng and RWG. Ginsenoside $Rg_3$ was more generated in red ginseng than in RWG. 3. Ginsenoside $Rh_2$ appreared during steaming and drying of cultivated ginseng, whereas it was more increased during steaming and drying of CWG. 4. Ginsenoside $Rg_1$ content was more increased during steaming and drying of cultivated ginseng, whereas it was more decreased during steaming and drying of CWG. 5. Ginsenoside $Rb_1$ content was increased about 500% during steaming and drying of cultivated ginseng, whereas it was increased about 30% during steaming and drying of CWG, indicating that ginsenoside $Rb_1$ was more generated in red ginseng than in RWG. 6. Ginsenoside $Rg_3$ content was higher, whereas ginsenoside $Rg_1$ content was lower in 11th RWG than in 9th RWG, indicating that ginsenoside $Rg_3$ content was increased and $Rg_1$ content was decreased as steaming and drying continued to proceed. Ginsenoside $Rh_2$ and $Rb_1$ contents began to be increased, followed by decreased after 9th steaming and drying process. Conclusions Above experiment data can be an important indicator for the dentification of ginseng, red ginseng, CWG, and RWG. And the following studies will be need for making good product using CWG.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.39 no.2
• /
• pp.19-27
• /
• 2016

Maritime transport is now regarded as one of the main contributors to global climate change by virtue of its $CO_2$ emissions. Meanwhile, slow steaming, i.e., slower ship speed, has become a common practice in the maritime industry so as to lower $CO_2$ emissions and reduce bunker fuel consumption. The practice raised various operational decision issues in terms of shipping companies: how much ship speed is, how much to bunker the fuel, and at which port to bunker. In this context, this study addresses an operation problem in a shipping companies, which is the problem of determining the ship speed, bunkering ports, and bunkering amount at the ports over a given ship route to minimize the bunker fuel and ship time costs as well as the carbon tax which is a regulatory measure aiming at reducing $CO_2$ emissions. The ship time cost is included in the problem because slow steaming increases transit times, which implies increased in-transit inventory costs in terms of shippers. We formulate the problem as a nonlinear lot-sizing model and suggest a Lagrangian heuristic to solve the problem. The performance of the heuristic algorithm is evaluated using the data obtained from reliable sources. Although the problem is an operational problem, the heuristic algorithm is used to address various strategic issues facing shipping companies, including the effects of bunker prices, carbon taxes, and ship time costs on the ship speed, bunkering amount and number of bunkering ports. For this, we conduct sensitivity analyses of these factors and finally discuss study findings.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.6
• /
• pp.620-625
• /
• 2015

In an effort to reduce the onset of global warming, the International Maritime Organization Marine Environment Protection Committee (IMO MEPC) proposed the reduction in ship speeds as a way of lowering the proportion of carbon dioxide ($CO_2$) in the Green House Gas emissions from ships. To minimize fuel costs, shipping companies have already been performing slow steaming for their own fleets. Specifically, the slow steaming approach has been adopted for most ocean-going container lines. In addition, because of the increased marine fuel cost that is required to enable increased capacity, there is an urgent need for more advanced fuel-saving technologies. Therefore, in this present study, we propose a fuel-cost reduction method that can improve the performance of diesel engines. We introduce a predetermined amount (0.025% of the amount of fuel used) of fuel additive (oil-soluble calcium-based organometallic compound). For improved experimental accuracy, as the test subjects, we utilize a large two-stroke diesel engine installed in land plants. The loads of the test engine were classified as low, medium, and high (50, 75, and 100%, respectively). We compare the engine performance parameters (power output, fuel consumption rate, p-max, and exhaust temperature) before and after the addition of fuel additives. Our experimental results, confirmed that we can realize fuel-cost savings of at least 2% by adding the fuel additive in low load conditions (50%). Likewise, the maximum combustion pressure was found to have increased. On the other hand, we observed that there was a reduction in the exhaust temperature.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.3
• /
• pp.224-230
• /
• 2015

Vessels are traditionally optimized for a single condition, normally the contract speed at the design draft. The actual operating conditions quite often differ significantly. At other speed and draft combinations, adjusting the trim can often be used to reduce the hull resistance. Changing the trim is easily done by shifting ballast water. There are several ways to assess the effect of the trim on the hull resistance and fuel consumption, including in-service measurements, model tests, and CFD. In this paper, CFD is employed for the assessment of the resistance performance according to the trim conditions. The commercial CFD code of the STAR-CCM+ is utilized to evaluate the ship’s resistance performance on a 6,800 TEU container ship. To validate of the effectiveness of STAR-CCM+, the experimental result of the KCS hull form is compared with the result from STAR-CCM+. It is found that the total resistance of the 6,8000 TEU container ship was reduced by 2.6% in the case of a 1-m trim by head at 18knots.

• Journal of Navigation and Port Research
• /
• v.36 no.5
• /
• pp.409-418
• /
• 2012

Amid global economic crisis and skyrocketing oil prices, container shipping companies have raised a sustained series of efforts to reduce vessel operating costs. Under these circumstances, the Grand Alliance has decided to install the dedicated feeder instead of additional vessels in the CCX(Central China Express) and the NCE(North China Express) route. In other words, a vessel in a trunk route is transshiped by a dedicated feeder vessel in Busan port that is a transshipment port, rather than calling at Northen China port. In this study, the actual operating data of Grand Alliance container services were analyzed to determine the economic effect of transshipment through a dedicated feeder service. In this way, the Grand Alliance are saving vessel operating expenses in 'NCE' and 'CCX' routes, making the slow steaming of vessels possible in these trunk routes.