• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.7
• /
• pp.1017-1025
• /
• 2009

This study intends to study about the blade performance loss occurred due to the variation in the shape of airfoil from the attachment/non-attachment of blade erosion shield for hovercraft. This study model has used NACA 4412, has designed NACA 4412 by using Auto CAD and designed the shape that has attached an erosion shield to this model according to the thickness and length. By using these models, we have generated a grid by using GAMBIT and calculated the lift coefficient (Cl) and drag coefficient (Cd) by using the FLUENT code for flow analysis. Through this, we have calculated and compared the lift-to-drag ratio that is an indicator of airfoil performance according to the shape and attachment/non-attachment of erosion shield.

• Proceedings of KOSOMES biannual meeting
• /
• 2007.05a
• /
• pp.175-180
• /
• 2007

Until a recent date Wan-do Port have been made efforts to advance its marine policy toward the base of marine distribution industry. Therefore the administration of Wan-do port have been carried out many projects on improvements of harbour system very actively. The improvement of ship traffic system would be one of them. This research examined the general view of present situations of marine traffic system in Wan-do waters area and suggested improvements in ship route and anchorage.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1997.04a
• /
• pp.53-70
• /
• 1997

The purpose of this study is to propose what developments for Korean Maritime high school are. In order to find out some proposals, the concerned literature survey and sata are used accordingly. This paper is consisted of 4 chapters. The contents of first chapter are focused on the study purpose and problems facing on the maritime high schools. The second are on the present situation of these schools. The third are on the improving proposals, the fourth are on the conclustions of this paper. The following proposals are abstracted through this study. The first, competent authority should be transferred to ministry of education from ministry of marine. The second, education system should be upgraded to junior college or 5 years education course. The third, maritime university permission should be opened for maritime high schol graduates. The fourth, training ship should be build for effective training course required from STCW 95. The fifth , if the graduates from maritime high school engage on board , all of them should be exempted from military service responsibility. The sixth , the education course should be diversified according to the need and demand from the industry society and students. The seventh, the on board-training system for teachers and instructors should be programmed in order to help them keep and utilize the on board experience in actural eudcation situation.

• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.2
• /
• pp.86-94
• /
• 2023

Tonnage taxation has contributed to developing the Korean maritime industry through tax relief for shipping companies. The current tonnage taxation relies on the net tonnage as an earning-capacity indicator in a merchant ship. Although the tonnage tax accords with horizontal equity, it does not match vertical equity because of the different taxable capacities of an individual company. Nowadays, maritime transport uses a dedicated vessel, and each shipping freight embeds a different value of time. It means the tonnage taxation regime should consider the added value of each shipping freight. Meanwhile, as the environmental regulations led by the International Maritime Organization are being strengthened, the Korean merchant fleet must be eco-friendly soon after. This study explores the alternative to renewing tonnage taxation by utilizing the Greenship certification and considering the ability-to-pay principle. Because the Greenship certification scheme encourages shipping decarbonization, maritime transport by a certified ocean-going vessel comes to be treated as an activity for the green economy. Special taxation for the green economy may contribute to shipping sustainability and market competitiveness.

• Journal of Navigation and Port Research
• /
• v.40 no.5
• /
• pp.329-336
• /
• 2016

The overall purpose of this paper is to conduct research on alternatives for strengthening the competitiveness of a state-run shipping company, Vinalines Corporation, the largest shipping and maritime enterprise in Vietnam. The first section of the introduction gives a panoramic overview of the current development situation of the Vietnam maritime industry and Vinalines. After summarizing a literature review in section 2, some alternatives are proposed in sections 3 and 4 to overcome the current difficulties of Vinalines and to improve the corporation's competitiveness for sustainable development by utilizing linear optimization and financial analysis. The final section presents a summary and recommendation for future study. It is concluded that privatization is the key solution for every problem faced by the corporation at present. Furthermore, modification of laws, restructuring of enterprise governance, financial situation, and fleet are also extremely necessary.

• Journal of Advanced Marine Engineering and Technology
• /
• v.27 no.4
• /
• pp.503-510
• /
• 2003

A new method of induction motor drive, which requires neither shaft encoder nor speed estimator, is presented. The proposed scheme is based on decreasing current gap between a numerical model and an actual motor. By supplying the identical instantaneous voltage to both model and motor in the direction of reducing the current difference. the rotor approaches to the model speed. that is. reference value. The indirect field orientation algorithm is employed for tracking the model currents. The performance of induction motor drives without speed sensor is generally characteristic of poorness at very low speed. However, in this system, it is possible to obtain good speed response in the extreme low speed range.

• Journal of electromagnetic engineering and science
• /
• v.9 no.2
• /
• pp.53-60
• /
• 2009

Remarkable developments in the electric and electronic industry have given people's daily life much more convenience and abundance. However, in electrical communication, or electric and electronic fields, making electrical and electronic devices more functional, more integrated, and faster have put electromagnetic interference(EMI) into more complex forms, and lots of problems such as interruption, malfunction, or interference by noise between electrical communication systems occurs every day. In this research, the electromagnetic compatibility(EMC) filter in the high powered breaker was designed and fabricated as a counter measure. The filter attenuated noise more than 20${\sim}$50 dB in the range of 10 MHz${\sim}$1.5 GHz. And, when the electric fast transient(EFT) of 4 kV in the level 4 of IEC 61000-4-4 was induced, it was soon suppressed to 600 V.

• Journal of electromagnetic engineering and science
• /
• v.4 no.2
• /
• pp.51-55
• /
• 2004

With the progress of the electronics industry and radio communication technology, certain problems, such as electromagnetic interference(EMI), have arisen due to the increased use of electromagnetic(EM) waves. International organizations such as CISPR, FCC, and ANSI have provided the standards for the EM wave environment and for the countermeasure of the electromagnetic compatibility(EMC). EM wave absorbers are used for constructing an anechoic chamber to test and measure EMI and electromagnetic susceptibility(EMS). In this paper, we have designed an one-body EM(electromagnetic) wave ferrite absorber, based on the equivalent material constants method for both normally and obliquely incident waves, whose absorption abilities are superior to that of the conventional ones. The fabricated absorber has a thickness of 27.68 mm and shows an absorption ability over 20 ㏈ in the frequency from 30 MHz to 6 ㎓.

• Nuclear Engineering and Technology
• /
• v.53 no.8
• /
• pp.2669-2681
• /
• 2021

Valve is widely used in the various industry areas to adjust and control the flow. Cavitation frequently takes place and sometimes is inevitable in various types of valve to cause the erosion damage. Therefore, how to control and minimize the effect of cavitation is still an important topic. This study numerically investigates the cavitating flow in a control valve with a perforated cage. The effects of some parameters on the cavitation are discussed. It also discusses to use the throttling steps to govern the cavitating flow. The results show that the opening degree of valve and the length of downstream divergent connection both influence the cavitation. The increase of the divergent length reinforces the cavitation. And the larger the opening of valve is, the intenser the cavitation is and the more vapor is present. The more throttling steps are helpful to decrease the cavitation.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.4
• /
• pp.319-327
• /
• 2016

Whereas shipping and Ship-building industries of Korea have been under the direct influence of International Maritime Organization (IMO) conventions and resolutions that aim at maritime safety and the protection of marine environment, it is needed that a specialized institute for dealing with IMO Agenda be established by industry-academy-government collaboration. Accordingly, this study proposes the establishment of a specialized institute to manage the IMO Agenda. To this end, integrating the existing bodies and their functions into a specialized institute, namely, the International Maritime Cooperation Center, is suggested. This center, composed of 40 researchers and operated by the Korea Maritime Institute, could assume this role. This study proceeds by building an estimate of the operational cost of the institute and exploring practical ways to finance it through the private and public sectors, also considering revisions to the Maritime Safety Act to ensure continuous operation of the new institute.