The scrubber is a device for removing sulfur oxides. It serves to reduce sulfur oxides by using water. Scrubber is being used in many places and has begun to be widespread as an environmentally friendly device. The scrubber installation is highly preferable, because the current high-sulfur fuel can be used in scrubber installed ships.

There are 3 different types of the marine scrubber: an open, a closed, and a hybrid type(American Bureau of Shipping, 2018). The open type uses external sea water to reduce sulfur oxides, but the closed type uses fresh water. The hybrid type uses seawater and f resh water alternately depending on the situation. However, the scrubber requires an installation space, resulting in a change in the conventional ship draft, DWT, equilibrium. The location and space for installation are different depending on the types of scrubber.

2.2 MGO(Marine Gas Oil)

Unlike scrubbers and LNG propulsion vessels, low-sulfur oil can be operated without any additional equipment. However, low-sulfur fuels are more costly than existing ship fuels and can present threats to the engines of vessels that are critical to the vessel, and there are also risks such as fires. The problem of the supply of low-sulfur oil from existing oil refineries is also influencial on the choice of shipping companies. MGO is expected to experience price differences due to production and blending.

LNG propulsion ship refers to a ship that replaces existing ship fuel with LNG. For existing vessels, it is necessary to reduce the sulfur content to 0.1 when they are passing ECA. Therefore, Herdzik, J(2011) said that various fuels should be loaded or the engine should be adjusted as needed.

LNG-propelled vessels are able to reduce this fuel operations and are increasing by an average of 26% per year(Lee et al., 2018). These have been widely used for ferries and other vessels, but now it is said that shipping companies are ordering LNG-propelled container vessels.

LNG-propelled vessels are used in many areas. These vessels are widely used on routes to Europe in the United States. Environmentally friendly ship-related equipment has been developed due to the revitalization and stability of eco-ships. Currently, the POSCO company is preparing for the standardization of LNG storage tanks developed by POSCO. In addition, a method for supplying fuel from LNG carriers is under consideration, and LNG is supplied using a tank lorry in Korea(Jang et al., 2015).

The government announced the construction of a repair shipbuilding cluster and the LNG bunkering plan at the Busan New Port for the revitalization of LNG vessels and formed an organization to train R&D specialists and environmentally friendly ship-related personnel. ISO(2017) enacted ISO 20519 to facilitate shipbuilding and provided training programs for crew members based on international standards for bunkering procedures on LNG carriers.

This study is for priority analysis of support policies for SOx emission from ships. We conducted a survey and analyzed it by AHP(Analytic Hierachy Process) that Saaty(1987) proposed. AHP is a very effective method to consider the important factors such as objectives, targets, standards, and conflicting alternatives. Each factor was derived before analyzing the priority of support policies for shipping sulfur oxides emission control. The 16 detailed subcriteria was derived by literature research and expert interviews. The results of the four top criteria comprised of Cost Factor, Operating Factor, Support Factor, and Policy Factor are shown in Table 2.

As previously mentioned, in order to investigate the priority of regulation-related support policies for shipping sulfur oxides emissions, the overall criteria were classified into upper criteria and lower subcriteria. Cost Factor was classified into Financial Aid, Loan Benefit, Tax Favor, and Incentive. Operating Factor was divided into Professional Manpower Training, Education and Training, Research and Development, and Equipment Development. The Support Factor consisted of Business Support, Provision of Information, Counseling Service, and Community. The Policy Factor was classified into Expansion Management Plan, Construction Cluster, Construction Infrastructure, and Government Support. The detailed hierarchical structure of the research is as Fig. 1.

This survey was conducted over seven days from September 11th to September 17th, 2018. In the questionnaire of 40 participant collected from shipping companies, we used 36 participant after excluding untrustworthy responses for analysis. In the AHP analysis, consistency can be confirmed by utilizing the C.R(Consistency Ratio) value. It is a value obtained by dividing C.I(Consistency Index) by R.I(Random Index). Generally, it is judged to be consistent when it is smaller than 0.1(Kim and Kang, 2002). As all C.R values in this questionnaire is less than 0.1, it is sure that this survey is reliable. We were able to confirm the characteristics of the respondents through the response of many respondents. First of all, 10 deputy general manager replied the questionnaire, and 6 assistant manager and 6 general manager participated. In the case of employment history, the respondents that replied more than 10 years occupied the highest frequency of 17 participant. Details are as Table 3.

The analysis of the top criteria showed Cost Factor(0.578), Operating Factor(0.158), Policy Factor(0.135), and Support Factor(0.130). The relative importance of the Cost Factor was highest compared to other factors. Within the Cost factor, the relative importance of the detailed subcriteria were analyzed in the order of Financial Aid(0.481), Loan Benefit(0.272), Tax Favor(0.143), and Incentive(0.005). The priority of Financial Aid was particularly high. This is an item about whether it is possible to support the replacement or purchase of a ship, which is a factor that is highly evaluated relative to the Loan Benefit or Tax Favor. To cope with the sulfur oxides emission regulations, we should implement the new or modified methods for ships, which is very costly if the ship is newly built. It is because the cost burden is a very sensitive issue for the operation of the company.Table 4

The analysis of the top criteria showed that the second highest was Operating Factor. The subcriteria and relative importance within this Operating Factor were Professional Manpower Training(0.412), Education and Training(0.260), Research and Development(0.178), and Equipment Development(0.150). The result showed that the training related subcriteria were relatively important, because the burden of using the newly added equipment was projected. Also it reflects that the training of specialist personnel is an essential factor for the stable operation of the ship and the need for re-training of the existing crew is increasing.

The subcriteria and relative importance within Policy Factor were Government Support(0.317), Expansion Management Plan(0.305), Construction Cluster(0.196), and Construction Infrastructure(0.182). Analysis of the detailed items of Policy Factor showed that the priority for Government Support was the highest. The Government Support, which means expanding support through agencies such as the Korea maritime finance corporation, has a high impact on shipping companies than the other subcriteria within Policy Factor. It seems that the activities such as supporting related infrastructures and fostering clusters have an indirect impact on the operation of shipping companies. In the preparation process for sulfur oxides emission regulations, shipping companies are more aware of the need for immediate realistic and direct support.

Finally, the Support Factor consisted of Business Support(0.456), Provision of Information(0.289), Counseling Services(0.146), and Community(0.109). Compared to other subcriteria, the priority of Business Support was very high. Business Support means the support for equipment replacement, ship purchase, and sale. It especially supports service for foreign language interpretation and expertise. In a preliminary interview, we had an impression that most companies except large corporations did not fully understand SOx emission regulations. If you purchase new equipment and vessels to prepare for sulfur oxides emission regulations, additional work would be added to the current ship operation. Therefore, it is considered that the shipping companies highly evaluate the priority of Business Support.

The subcriteria with higher priorities regarding overall combined weight were Financial Aid(0.278), Loan Benefit(0.157), Tax Favor(0.083), Professional Manpower Training(0.065), and Incentive(0.060). It can be seen that all of the subcriteria except for the Training of the Manpower, which is the fourth rank, are the items included in the Cost Factor. As mentioned earlier, shipping companies inevitably feel burdensome with the need for additional costs in operating businesses. In particular, the priorities analyzed in the order of Financial Aid, easing of loan qualification requirements, interest Loan Benefit, and acquisition tax reduction support was cost related items that could alleviate the operating burden of shipping companies. In the subcriteria of Support Factor, the Counseling Service(0.019) and the Community(0.014) ranked 15th and 16th respectively, with very low relative priorities. The need for Counseling Services related to the implementation of regulations and support related to the formation of communities among shipping companies was lower than other subcriteria.