• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.5
• /
• pp.589-601
• /
• 2014

Natural gas hydrate (NGH) is emerging as a new eco-friendly source of energy to replace fossil fuels in the 21st century. It is well known that the Natural Gas Hydrate contains large amount of natural gas about 170 times as much as its volume and it is easy to be stored and transported safely at about $-20^{\circ}C$ under atmospheric pressure due to so called "self-preservation effect". The option of gas transport by gas hydrate pellets carrier has been investigated and developed in various industry and academy. The natural gas hydrate pellet carrier is on major link in a potential gas hydrate process chain, starting with the extraction of natural gas from the reservoir, followed by the production of hydrate pellets and the transportation to an onshore terminal for further processing or marketing. In recent years, Korean project team supported by Korean Government has been working on the development of NGH total systems including novel NGH carrier since 2011. In order to increase the knowledge on the NGH pellet carrier developed and to understand the major hazards that could have significant impact on the safety of the vessel, this paper presents and evaluates the pros and cons of cargo holds, loading and unloading systems through the analysis of current patent technology. Based on the proven and well-known technologies as well as potential measures to mitigate sintering and minimize mechanical stress on the hydrate pellet in the self-preservation state, this study presents the conceptual and basic design for NGH carrier.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.25 no.2
• /
• pp.61-69
• /
• 1989

Mackerel purse seine fishery operating in the sea area of Cheju and Tsushima is one of the most important fishery in Korean off shore fishery, which a fishing fleet are generally composed with one purse seiner, two light ships and three or four fish carriers. In this study, purse seiners are classified in to four classes in term of their gross tonnage : A class(80-100tons), B class(100-120tons), C class(130-140tons), and D class(140-150tons). Operating sea area are divided into five sectors including east and west sea area of Tsushima Island, coastal sea area of Cheju Island and south and west sea area of Cheju Island. The performance of the purse seiner, the fishing efficiency, the dimension of fishing gear and variation of CPUE in each operating sea area are summarized as follows: 1. The relationship between a gross tonnage x and net area of purse seine y of a purse seiner can be expressed as : y=538.8x+99657.3 2. The index of seasonal variation of CPUE from May to October is lower than the standard value, whereas index from November to April is higher. 3. The power factor of fishing efficiency by classes of boat-size shows significant differences with 1% level in each operating sea area. 4. The net efficiency of purse seiner by classes of boat-sea shows that B and C classes are higher than A and D classes.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.3
• /
• pp.174-179
• /
• 2016

To protect the ocean environment, the use of liquefied natural gas (LNG) carriers, bunkering ships, and fueled ships is increasing. Recently, Korean shipbuilders have developed and supplied a partial reliquefaction facility for boil-off-gas (BOG). Despite reasonable insulation, heat leakage in vessel storage tanks causes LNG to be continuously evaporated as BOG. This research analyzed the maximum liquid yield rate for various partial reliquefaction systems (PRS) and considered related factors affecting yields. The results showed a liquid yield of 48.7% from an indirect PRS system (heat exchanges between cold flash gas and compressed natural gas), and 41% from a direct PRS system (BOG is mixed with flash gas and discharged from a liquid-vapor separator). The primary factor affecting liquid yield was heat exchanger effectiveness; the exchanger's efficiency and insulation characteristics directly affect the performance of BOG reliquefaction systems.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.26 no.2
• /
• pp.132-138
• /
• 2018

Aviation safety requires systematic national attention and management because aircraft accident produce greater undesired social impact, economical damage, and declining national credibility compare to other transportation accident. Specially, Republic of Korea has highly increased risk of air accident as a major air transportation point having small aerospace, connecting pacific ocean and Asia, and explosively increased air traffic produced by economical growth, operating numerous military aircraft for the South and North Koreas' confrontational situation. Also, greatly increased domestic and oversea air travels by Koreans and foreigners as well as air freight based on heightened Korea's national power, launching new low cost carriers, and popularized leasure aviation have produced large amount of aviation needs in various fields. However, national aviation safety management system gratifying increased aviation needs and aircraft operations is seem to be slow in progress. This paper will show optimized measures utilizing private, governmental, and military resources to prevent aircraft accident under circumstances of limited budget and an favorable conditions, then will propose several action items.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.3
• /
• pp.287-297
• /
• 2019

The recent increase in crude oil trading has led to an increase in the workings of SPM for crude oil carriers. VLCCs generally encounter difficulty entering port due to limitations in terms of sea depth and maneuverability. The SPM is a system that allows mooring to the buoy located in the outer sea for such vessels. However, the buoy is more affected by relatively external forces because of their of shore location. Therefore, the safety assessment of SPM is particularly important as it can lead to large oil pollution disasters in the event of SPM accidents. Despite this, in the implementation of the Marine Traffic Safety Audit Scheme in Korea, there exists no guidance for SPM. In this study, a SPM mooring safety assessment is performed using OPTIMOOR, a numerical analysis program, so as to understand the mooring characteristics of SPM. As a result, it is confirmed that the tension of mooring lines and hull movement in the SPM are greatly affected by the encounter angles with external forces. In addition, it is found that the maximum tension of the mooring line is elevated as the water depth becomes shallower through sensitivity analysis. According to SPM characteristics, which has a large influence on the encounter angle, this study has proposed an amendment to setting criteria in the implementation of the Maritime Traffic Safety Audit Scheme which could improve the reliability and accuracy of mooring safety assessments.

• Journal of Navigation and Port Research
• /
• v.38 no.1
• /
• pp.19-27
• /
• 2014

When a ship operates in a shallow water and channel, the hull sinkage and asymmetrical force generated around the ship by the influence of sea bottom and bank walls are caused collision with sea bottom, other ships or the bank itself. Especially, the shipping company and pilots navigating the area of Europe and North America with many channels are deal with it as a important matter to prevent collision. In this paper, hydrodynamic force generated between the ship and bank using the numerical analysis for the safe navigation of ship, that is, sway force and yaw moment should be presumed qualitatively. It makes a program for fluid analysis of the shallow water and bank effect. Analyses are carried out for three kind of parameter, that is, ship's speed, water depth and ship-bank distance for crude oil carriers. The numerical analysis results are compared with results of the experiments and the previous published papers.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.10
• /
• pp.1002-1010
• /
• 2015

Natural gas hydrates are newly emerging as an environment-friendly source of energy to substitute for fossil fuels in the 21stcentury.NGHs are reported to holds much amounts of natural gas (up to 182 standard volumes of gas per volume of hydrate); they are easy to store and safe to carry at about minus 20 degree Celsius under atmospheric pressure because of the self-preservation phenomenon of gas hydrates. The transporting method by gas-ice-hydrate ship carriers has been introduced and developed by a variety of industry and research institutions. Our team has been conducted to develop NGH total systems, including a breakthrough NGH carrier for sea transportation, since 2011. The NGH pellet carrier does not require a separate cooling system for cargo, and the initial temperature is maintained through insulation of the cargo tanks throughout the transport to the final destination. The heat conducted from the exterior and passing through the insulation material of the hull should be cut off as much as possible, but heat inflow inside the cargo tank from an external source is inevitable during transport. In this study, the heat transfer in a cargo tank of a 115K NGH carrier was analyzed through simulation with a commercial CFD code to estimate the boil-off gas/boil-off rate on the developed carrier and understand major hazards that could significantly impact the safety of the vessel.

• The Journal of shipping and logistics
• /
• v.27 no.1
• /
• pp.79-98
• /
• 2011

The volume of the world's container transportation has been increasing. To serve this transportation need, the size of the container carrier is getting larger. The global ports are required to deepen the waterways as well as to prepare infrastructure to serve these super-size container carriers. However, few ports around the world could meet the requirements. To solve these difficulties, the concept of the Mobile Harbor has been developed. An onboard Automatic Storage and Retrieval System(AS/RS) has been proposed for the B1 type Mobile Harbor to maximize the container throughput within the limited space of the Mobile Harbor. A scenario of operations and freight movements of the B1 type Mobile Harbor is prepared and the storage size of the B1 type Mobile Harbor through the computer simulation is estimated. The size of the Mobile Harbor and the size of the AS/RS has also been estimated. The optimized size of the Mobile Harbor could be proposed.

• Environmental and Resource Economics Review
• /
• v.33 no.3
• /
• pp.291-314
• /
• 2024

The International Maritime Organization (IMO) has strengthened environmental regulations, leading to an increase in demand for LNG-powered ships. To enhance the competitiveness of ports and promote the use of LNG-powered ships, establishing LNG bunkering infrastructure is necessary. However, no ports in Korea currently have such infrastructure. This study used the 2015 regional input-output table to examine the economic impact of establishing LNG bunkering infrastructure in Busan Port, the largest port in Korea. The estimated cost of the project in 2023 was KRW 21.09 billion. The average production, value-added, and employment inducement coefficients were 1.223, 0.372, and 7.58, respectively.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.1
• /
• pp.10-16
• /
• 2016

Fatigue analysis for life extension of a ship is different from that of a newly constructed ship since the current corrosion margin and voyage routes of the past and future must be considered, thereby complicating the life extension procedure. This research introduces the fatigue analysis case for the life extension project of a moss LNG carrier using full spectral fatigue analysis, which has been previously used for newly constructed ships. It is expected that the fatigue analysis methodologies and full spectral fatigue analysis program used in this study will be applicable to other life extension projects.