• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.96-103
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• 2014

Liquefied Petroleum Gas(LPG) has attracted attention as a alternative fuel. The lean-burn LPG direct injection engine is a promising technology because it has an advantage of lower harmful emissions. This study aims to investigate the effect of combustion strategy and excess air ratio on combustion and emission characteristics in lean-burn LPG direct injection engine. Fuel consumption and combustion stability were measured with change of the ignition timing and injection timing at various air/fuel ratio conditions. The lean combustion characteristics were evaluated as a function of the excess air ratio with the single injection and multiple injection strategy. Furthermore, the feasibility of lean operation with stratified mixture was assessed when comparing the combustion and emission characteristics with premixed lean combustion.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.100-106
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• 1998

The wide open throttle performance and piston temperatures were measured by the change of fuel : gasoline and liquefied petroleum gas(LPG). Bench test method was developed and experimented to study the effect of temperature on the formation of carbon deposit. The bench test results were confirmed by measuring the piston temperature and observing the deposit production rate at an actual engine running condition. Results show that if the fuel of spark ignition engine is changed from gasoline to LPG, the output power decreases about 10% and the piston temperatures increase about 40~55$^{\circ}C$. In actual engine tests, because of this temperature increase, it was observed that the quantity of carbon deposit in the top ring groove increased in a big degree. Consuquently, it is known that the fing sticking may occur if the gasoline engine was rebuilt to LPG fuelled engine. Therefore, in order to preserve the durability of LPG fuelled engine, it is necessary to lower the piston temperature by hardware modificationor to reduce the carbon deposit by the improvement of engine oil.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.99-106
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• 1996

Development of an automatic TIG welding system incorporating a vision sensor and torch control mechanism leads to an improved welding quality and greater production efficiency. The automatic welding system should be greatly restricted in its size and weight for the LNG(Liquefied Natural Gas) storage tank and also provide a unique torch rotating mechanism which keeps the torch tip in the constant position while the angle is changed continuously to maintain the welding torch substantially perpendicular to the weld line. The developed system is driven by two translation axes X, Z and one rotational axis. A moving line window method is adopted to the image recognition of the corrugated membranes with specular reflection. This method decides original laser stripe patterns in image which is affected by multi-reflection. A self-teaching algorithm, which guides the automatic welding machine with the information provided by the CCD camera without any previous learning of a reference trajectory, was developed for tracking the corrugated membrane of the LNG tank along the weld line.

• Journal of ILASS-Korea
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• v.16 no.1
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• pp.1-6
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• 2011

In recent years, the need for more fuel-efficient and lower-emission vehicles has driven the technical development of alternative fuels such as LPG (Liquefied Petroleum Gas) which is able to meet the limits of better emission levels without many modifications to current engine design. LPG has a high vapor pressure and lower viscosity and surface tension than diesel and gasoline fuels. These different fuel characteristics make it difficult to directly apply the conventional gasoline or diesel fuel pump. Self acting lubricated groove design or coating can be used in high-speed and high precision spindle system like a roller-vane type fuel pump, because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy and simplicity in manufacturing. Those design method can also affect the atomization of fuel from the injector and the formation of fuel film on the intake manifold. In this study, experiments are carried out to get performance characteristics of initial and steady state operation, The characteristics of vane type fuel pump were investigated to access the applicability on LPLi engine.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.40-48
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• 2015

As advantages of LPG-DI engine, LPG is directly injected into combustion chamber during compression stroke to reduce compression temperature, prevent knock and spontaneous combustion, and adjust engine output using the amount of directly injected fuel, thereby reducing pumping loss caused by throttle valve. Stratified charge can be supplied nearby spark plugs to allow for overall lean combustion, which improves thermal efficiency and can cope with problems regarding emission regulations. In addition, it is characterized by free designing of intake manifold. Despite the fact that LPG-DI has many advantages as described above, there is lack of detailed investigation and study on spray characteristics, combustion flame characteristics, and ignition probability. In this study, a visualization experiment system that consists of visualization combustion chamber, air supply control system, emission control system, LPG fuel supply system, electronic control system and image data acquisition system was designed and manufactured. For supply of stratified charge in the combustion chamber, alignment of injector and spark plugs was made linear.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.1
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• pp.117-123
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• 2003

In a bi-fuel engine using gasoline and LPG fuel, with the current ignition timing for gasoline being used, the effective performance could not be taken in LPG fuel supply mode. The ignition timing in LPG fuel mode must be advanced much more than that of gasoline mode for the compensation of its lower flame speed, due to engine torque drop. This study aims to develop the control system for ignition spark timing conversion which is composed of hardwares and control algorithm for gasoline/LPG engine. We propose the control system which can advance the ignition spark timing in LPG fuel mode more than used in gasoline fuel mode. The advance of ignition timing is achieved by change of the ignition dwell time of coil igniter. The engine torque and F/E(Fuel-Economy) in LPG fuel mode are measured to evaluate the difference of engine performance between before and alter changing ignition spark timings. The engine torque and F/E are increased respectively, which proves the developed control system is effective so much for gasoline and LPG bi-fuel engine.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1384-1390
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• 2004

The full containment Liquefied Natural Gas(LNG) storage tank is based on a double liquid container concept : two separate containers, one within the other, are capable of containing the LNG. The outer concrete tank provides comer protection(secondary containment) to withstand and safely contain any spill from the inner tank. The comer protection is installed on inside corner surface of outer concrete tank. Because of high and complex stresses, corner protection is designed by ASME section ⅧI Div. 2, Appendix 4 on behalf of API 620 which is main design code for LNG tank. Design guidelines to determine design factors such as liner thickness and knuckle radius are not well understood because Appendix 4 is the design method not based on equation but FEM. Recently, the volume of LNG tank shows a tendency to increase. So it is necessary to set up the design guidelines to cope with change of LNG tank capacity and height/diameter ratio. In this paper, optimum design of corner protection was performed and the design guidelines were suggested by the results of FEM for LNG tanks which have different capacities and height/diameter ratio.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1-6
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• 2007

The membrane type LNG(Liquefied Natural Gas) cargo containment system is a special design structure for the large deformation behavior at LNG temperature$(-162^{\circ}C)$. The design of membrane is required great confidence so that membrane can plat role in the tightness of flammable fluid storing. LNG cargo containment is loaded and unloaded LNG between twice and five times in a week. During this process, the membrane has large deformation behavior due to the variation of temperature and pressure to the self weight. In this study, the evaluation of the fatigue strength of membrane is very important to determine the design life of LNG storage tank and to evaluate the mechanical properties at the LNG temperature. Also, in the view point of large deformation, the evaluation method is applied conservatively $\epsilon-N_f$ curve of SUS 304L.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.343-349
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• 2020

As global warming accelerates due to global climate change, the International Maritime Organization(IMO) has set up Emission Control Area(ECA) and encourages the use of Liquefied Natural Gas(LNG). For this reason, as the demand for LNG increases, the demand and research of related equipment also increases. In this study, one of them, the vent mast for the discharge of LNG was studied. In general, vent mast receives various loads such as wind load, earthquake load and dead load during operation. Accordingly, consideration of these loads is essential for structural design and safety evaluation of the vent mast. In this study, the structural safety of the vent mast is evaluated by performing finite element analysis. As a result, the structural safety evaluation results were analyzed based on the database of materials of the vent mast, and the stress level was analyzed to provide a design guide.

• Computers and Concrete
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• v.17 no.2
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• pp.201-214
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• 2016

The outer tank of a liquefied natural gas (LNG) storage tank is a longitudinally and meridianally pre-stressed concrete (PSC) wall structure. Because of the current trend of constructing larger LNG storage tanks, the pre-stressing forces required to increase wall strength must be significantly increased. Because of the increase in tank sizes and pre-stressing forces, an extreme loading scenario such as a bomb blast or an airplane crash needs to be investigated. Therefore, in this study, the blast resistance performance of LNG storage tanks was analyzed by conducting a blast simulation to investigate the safety of larger LNG storage tanks. Test data validation for a blast simulation of reinforced concrete panels was performed using a specific FEM code, LS-DYNA, prior to a full-scale blast simulation of the outer tank of a 270,000-kL LNG storage tank. Another objective of this study was to evaluate the safety and serviceability of an LNG storage tank with respect to varying amounts of explosive charge. The results of this study can be used as basic data for the design and safety evaluation of PSC LNG storage tanks.