• Special Issue of the Society of Naval Architects of Korea
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• 2007.09a
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• pp.48-56
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• 2007

Wash primer was applied to cargo tank of Membrane-LNG Carrier (M-LNGC) for corrosion resistance and high bond-strength with the mastic. However, a lack of bond-strength verification at high thickness wash primer coating resulted in strict coating thickness control. Therefore wash primer was controlled below DFT(Dry Film Thickness) $30{\mu}m$. In order to develop the wash primer satisfying GTT (GAZ TRANSPORTAION TECHNIGAZ) standard even at high thickness, we evaluated coating properties such as wash primer/mastic bond-strength, corrosion resistance, as well as workability for the newly formulated wash primer materials. The newly formulated wash primer had high bonding-strength to mastic even at high thickness and had proper corrosion resistance and workability suitable to yard condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1390-1397
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• 2004

This study is concerned with the thermal analysis during the cool-down period of 135,000㎥ class GT-96 membrane type LNG carrier under IMO and USCG design condition. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls down from -4$0^{\circ}C$ to -l3$0^{\circ}C$, and the spraying rate for the cooling of the insulation wall increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the first barrier and the first insulation, which are among the insulation wall, especially in the top side of the insulation wall under IMO and USCG design condition. Also, as the NG temperature distribution is fixed, the outer temperature condition under the design condition has influence on the temperature variation at the insulation. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted under IMO and USCG design condition. From the comparison between two conditions; IMO design condition shows more severe temperature gradient than USCG design condition, therefore, it provides the conservative estimation of the BOG.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1024-1031
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• 2012

In this paper, FMCW type radar level transmitter using correlation analysis method is implemented for precise distance measurement of cargo tank. FMCW type radar level transmitter is the device for distance measurement which calculates the distance by analyzing the beat frequency, that is, the frequency difference between Tx and RX signal from radar antenna using Fast Fourier Transform(FFT), but compensated algorithm like Zoom FFT is needed for the improvement of the frequency precision because the frequency precision of FFT is limited depending on sampling frequency and the number of sampling data. In case of Zoom FFT, the number of sampling data and noisy signal are the main factor influencing the measurement accuracy of Zoom FFT like FFT. Therefore, in order to overcome the limited environment and achieve the precise measurement, correlation coefficient is used for the distance measurement and the errors of measurement are verified to be in the range of ${\pm}1mm$.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.1
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• pp.131-139
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• 2022

The exchange of goods over the sea is a situation in which the amount of trade between countries is gradually increasing. In order to maintain the optimal operating condition, the ship maintains stability and optimal operating conditions by inserting or withdrawing ballast water from the ballast tank according to the loading condition of cargo capacity is also increasing. Control valves play an important role in controlling fluid flow in these pipes. When the flow rate is controlled using a control valve, problems such as cavitation, flashing, and suffocating flow may occur due to high differential pressure, and in particular, damage to valves and pipes due to cavitation is a major problem. Therefore, in this study, the cavitation phenomenon is reduced by installing orifices at the front and rear ends of the high differential pressure control butterfly valve to reduce the sudden pressure drop at the limiting part of the butterfly valve step by step. The flow coefficient according to the shape of the orifice, the degree of cavitation occurrence, and the correlation were analyzed using a CFD(Cumputational Fluid Dynamics), and an optimal orifice design for reducing cavitation is derived.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.225-231
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• 2013

Liquefied gas carriers generally transport cargoes of flammable or toxic nature. Since these cargoes may cause an explosion, fire or human casualty, the accommodation spaces, service spaces and control stations of liquefied gas carriers should be so located as to avoid ingress of gas. For this reason, the paragraph 8.2.9 of IGC Code in IMO requires that the height of vent exits should be not less than B/3 or 6 m whichever is greater, above the weather deck and 6 m above the working area and the fore and aft gangway to prevent any concentration of cargo vapor or gas at such spaces. Besides as known, the LNG market has been growing continually, which has led to LNG carriers becoming larger in size. Under this trend, the height of a vent will have to be raised considerably since the height of a vent pipe is generally decided by a breadth of a corresponding vessel. Accordingly, we have initiated an examination to find an alternative method which can be used to determine the safe height of vent masts, instead of the current rule requirement. This paper describes the dispersion characteristics of boil-off gas spouted from a vent mast under cargo tank cool-down conditions in the membrane type LNG carriers.

• Land and Housing Review
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• v.6 no.2
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• pp.61-66
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• 2015

This study is the realization of natural gas as ways to advance the South and the continental railway linking basic research was conducted on railway transport. Summary data on the Status of North Korean railway which was to have reviewed the case of LNG railway transportation in Japan and China is becoming an LNG tank containers by rail transportation is done. In the case of Korea, the stability of railway transportation through the development of LNG tank containers and rail transportation pilot project was tested. It was set up and the basic directions of freight trains transport routes and methods for rail transport 7.5 million tons of natural gas per year. TKR ~ TSR between the LNG transportation business is an existing railway south. North. Russia gas pipeline (PNG) instead of a separate project to replace the business SRX (Silk Road Express) is a symbolic project for the early realization of the Eurasian railway linking policy. This study may give greater meaning to secure the iconic railway transport route for continental transport of containers and bulk cargo (coal, ores, etc.).

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.603-612
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• 2017

Accidents associated with hazardous materials, including oil and HNS, in maritime transportation show increasing trend. Therefore, preventive countermeasures for such accidents should be provided. The purpose of this study is to analyze level of risk on human loss and potential damage to environment, using data on domestic marine accidents carrying hazardous materials (2002~2014), and identify high-risk accident types for urgent risk management which needs findings of accident causes and proper mitigation measures. High-risks on human loss are explosion and suffocation, occurred in process of ship maintenance and tank cleaning. On the other hand, high-risk on environmental damage is spill caused by ship accidents (collision, grounding and etc.). Especially, spill occurs during loading operation of oil and HNS onboard a ship. Strict operation supervision/management and safety education/training on a regular basis could prevent accidents, because human factors such as not wearing safety gear and careless cargo handling cause most of the marine accidents.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.620-631
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• 2022

This paper shows the numerical prediction of the change in oil outflow rate according to the orifice shape of a damaged ship by using the computational fluid dynamics (CFD) analysis method. It also provides discharge coefficients for various orifice shapes to be used in theoretical prediction approaches. The oil outflow from the model ship was analyzed using a multiphase flow method under the condition that the Froude and Reynolds number similitudes were satisfied. The present numerical results were verified by comparing them with the available experimental data. Along with the aspect ratio of the orifice and the wall thickness of the cargo tank, the effects of the orifice shapes defined by mathematical figures on the oil outflow were investigated. To consider more realistic situations, the investigation of the ef ect of the crushed iron plate around the damaged part was also included. The numerical results confirmed the change in oil outflow time for various shapes of the damaged part of the oil tank, and discharge coefficients that quantify the viscous effects of those orifice shapes were extracted. To verify the predicted discharge coefficients, they were applied to an oil spill estimation equation. As a result, a good agreement between the CFD and theoretical results was obtained.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.269-274
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• 2009

Recently, the construction of Liquefied Natural Gas Carriers(LNGC) is being promoted larger and larger depending on long voyage. In 1950 years, $5,000m^3$ class of LNGC had been changed to $71,500m^3$ class in 1973. and to $210,000-266,000m^3$ class in 2007. Especially, the system of main engines and cargo control, Re-liquefaction of natural gases have become possible in LNGC. This research deals with the LNG projects, world markets of energy and developing tendency of liquefied natural gas carriers.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1076-1082
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• 2012

Today the welding for LNG carrier is known to be possible using arc and plasma arc welding process. But because of the lower energy density, arc welding is inevitable to multi-pass welding for thick plate and has a limit of welding speed compared to laser which is high energy density heat source. When thick plate is welded, weld defect by multi-pass welding and heat-affected zone by high heat-input were formed. Therefore one-pass welding by key-hole has been considered to work out the problems. It is possible for Laser, electron beam, plasma process to do key-hole welding. Nowadays, plasma process has been used for welding membrane of cargo tank for LNG carrier instead of arc process. Recently, many studies have examined to apply laser process to welding of membrane. In this paper, weldability, microstructure and mechanical properties of stainless steel for LNG carrier welded by fiber laser were compared to those by plasma. As a result, although the laser welding has several times faster speed, similar properties and smaller weld and heat affected zone were obtained. Consequently, this study proves the superiority of fiber laser welding for LNG carrier.