• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.377-381
• /
• 2005

The using of composite material is an aviation field but it changes into a general industry. Especially composites are expanding the use on transportation vehicles like automobiles, ships, and aircraft. The main factor of this expansion is high specific strength. It can supply a high quality and efficiency of energy. But manufacturing of composite products requires many raw materials and tooling cost for special process, so we needs a reduction of these costs to achieve best efficiency. In the present study, we contrast the change of mechanical and physical properties between VaRTM(Vacuum Assisted Resin Transfer Molding) and hand lay-up process. VaRTM process can offer a high quality the same as autoclave products, and low cost like hand lay-up process. In the results of mechanical tests, VaRTM specimen is stronger than hand lay-up specimen and hand lay-up specimen became delamination. In the results of physical tests, the resin content of VaRTM specimen is lower than hand lay-up specimen. On micrograph, the strength of specimen by VaRTM between fiber and resin is stronger than that of one by hand lay-up. And the specimen by hand lay-up contains more defects than one by VaRTM. So, VaRTM process can practically apply for automobile engine hood. This paper shows that VaRTM process is one of the most suitable processes for composite parts of automobile.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.7
• /
• pp.622-628
• /
• 2016

The prosperity of IT technologies and the removal of restrictions regarding Unmanned Aerial Vehicles (UAVs), also known as drones, have driven growth in their popularity. However, without a proper solution to the problem of accident avoidance for UAVs, this popularity increases the potential for collisions between UAVs and between UAV and terrain features. These collisions can occur because UAVs to date have flown using radio control or image recognition based autonomous navigation. Therefore, we propose efficient UAV routing schemes to tackle the collision problem using vehicular communication systems. Performance evaluation by computer simulation shows that the proposed methods effectively reduce the collision probability and improve the routing efficiency of the UAV. Furthermore, the proposed algorithms are compatible and can be directly applied with small overhead to the commercial vehicular communication system implementation.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.7
• /
• pp.563-568
• /
• 2016

In this study, experiments were conducted to evaluate the performance of a heat pump system. A heat pump system with an air as heat source is adapted as reference. The developed system uses a plate heat exchanger an evaporator to absorb heat from a stack of fuel cell driven electric vehicles. Hence, the system functions as a water source heat pump system. The results indicated that the; power consumption increased with the rotational speed of the compressor. A system performance($COP_h$) of 2.03 at an electronic expansion valve(EEV) openings of 25% and a compressor speed of 1200 rpm was observed in the reference system. However, at the same compressor speed, the $COP_h$ of the water source heat pump system corresponded to 9.42 at an EEV openings of 75%. It was found that the water source heat pump system exhibited the highest performance at a water temperature of $50^{\circ}C$.

• Journal of Korean Society for Atmospheric Environment
• /
• v.20 no.3
• /
• pp.317-330
• /
• 2004

The Purpose of this study was to develop the P $M_{2.5}$ source Profiles, which are mass abundances (fraction of total mass) of a chemical species in P $M_{2.5}$ source emissions. The source categories studied were soil, road dust, gasoline and diesel vehicles, industrial source, municipal incinerator, coal-fired power plant, biomass burning, and marine. The chemicals analyzed were ions. elements. and carbons. From this study, soil source had the crustal components such as Si, hi, and Fe. In the case of road dust. Si, OC, Ca, Fe had large abundances. The abundant species were S $O_4$$^{2-}$, C $l^{[-10]}$ , N $H_4$$^{+}$, and EC in the gasoline vehicle and EC, OC, C $l^{[-10]}$ , and S $O_4$$^{2-}$ in the diesel vehicle. The main components were S $O_4$$^{2-}$, S N $H_4$$^{+}$, and EC in the industrial source using bunker C oil as fuel, C $l^{[-10]}$ , N $H_4$$^{+}$, Fe, and OC in the municipal incinerator source, and Si, Al, S $O_4$$^{2-}$, and OC in the coal -fired power plant source. In the case of biomass burning, OC, EC, and C $l^{[-10]}$ were mainly emitted. The main components in marine were C $l^{[-10]}$ , N $a^{+}$, and S $O_4$$^{2-}$.EX> 2-/.

• Asian Journal of Atmospheric Environment
• /
• v.5 no.1
• /
• pp.41-46
• /
• 2011

The port of Busan is the fifth busiest container port in the world in terms of total mass of 20-foot equivalent units transported. Yet no attempts have been made to estimate the greenhouse gas (GHG) emissions from the port of Busan by accounting for all port-related activities of the various transportation modes. With these challenges in mind, this study estimates the first activity-based GHG emissions inventory in the port of Busan, which consists of four transportation modes: marine vessels, cargo-handling equipment, heavy-duty trucks, and railroad locomotives. The estimation results based on the most recent and complete port-related activity data are as follows. First, the average annual transportation GHG emission in the port of Busan during the analysis period from 2000 to 2007 was 802 Gg $CO_2$-eq, with a lower value of 773 Gg $CO_2$-eq and an upper value of 813 Gg $CO_2$-eq. Second, the increase in the transportation-related GHG emissions in the port of Busan during the analysis period can be systematically explained by the amount of cargo handled ($R^2$=0.98). Third, about 64% of total GHG emissions in the port of Busan were from marine vessels because more than 40% of all maritime containerized trade flows in the port were transshipment traffic. Fourth, approximately 22% of the total GHG emissions in the port of Busan were from on-road or railroad vehicles, which transport cargo to and from the port of Busan. Finally, the remaining 14% of total GHG emissions were from the cargo handling equipment, such as cranes, yard tractors, and reach stackers.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.10 no.3
• /
• pp.173-180
• /
• 2007

Oscillating wave amplitude in a bottom-mounted OWC chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. The numerical scheme employed a hybrid Green integral equation which adopts the Rankine Green function inside chamber to take account of fluctuating air pressure, while it uses the Kelvin Green function in outer domain. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• Journal of Power System Engineering
• /
• v.20 no.5
• /
• pp.29-36
• /
• 2016

Aluminum alloys have been widely used in engine materials, cold & hot-water storage vessels and piping etc., Furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston for various vehicles because of its properties of temperature, wear and corrosion resistance. Therefore, it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and to prolong its lifetime. In previous paper, the effect of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 16, 24, and 36 hrs)heat treatments to corrosion resistance and hardness were investigated using electrochemical method. In this study, in order to examine completely the effect of the tempering hours to hardness variation and corrosion resistance, the results of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 2, 4, 8 and 12hrs)heat treatments to hardness and corrosion resistance were investigated using electrochemical method. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment. Furthermore, the corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. And the tempering heat treatment temperature at $190^{\circ}C$ for 8 hrs exhibited the highest value of the hardness and also indicated the highest corrosion current density. However, the values of hardness and corrosion current density was again increasingly decreased with increasing of tempering hours than 8 hrs, Consequently, it is suggested that decision of the optimum. tempering hours is very important to improve the corrosion or wear resistance.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.2
• /
• pp.135-143
• /
• 2013

Friction Stir Welding (FSW) was developed, it is successfully commercialized in the field of transportation vehicles. In this study, we analyzed the defects of A2024-T4 alloy using non-destructive test of radiograph, ultrasonic, electrical conductivity and destructive test of microstructure observation, tensile strength. As the results of experiment, mapping of defects was obtained. Fine defects which were not detected in radiograph test were detected in ultrasonic test, and it enabled efficient detection of defects by difference of sound pressure and color. The values of electrical conductivity was decreased as amount of defects was increasing. Joint efficient of defect-free weldment that found by non-destructive and destructive test was 91%. Therefore it was considered that non-destructive test of friction stir welded A2024-T4 Alloy was an efficient method.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.9
• /
• pp.830-835
• /
• 2016

With the relaxation of regulations on unmanned aerial vehicles (UAVs) in the USA, the development of related industries is expected. Hence, it is anticipated that the number the UAVs will reach approximately 600,000 in the USA in 2017. However, automated flights of commercial UAVs are restricted owing to concerns about accidents. To deal with the possibility of collisions, several studies on collision prevention and the routing of UAVs have been conducted. However, these studies do not deal with various situations dynamically or provide efficient solutions. Therefore, we propose a centralized routing method for the UAV that uses vehicular networks. In the proposed scheme, vehicular networks regard UAVs as data packets to be routed. Accordingly, the proposed method reduces UAV processing power required for route searches. In addition, the routing efficiency for UAV flight paths can be improved since congestion can be minimized by using a vehicular network.

• Journal of the Society of Naval Architects of Korea
• /
• v.45 no.6
• /
• pp.656-668
• /
• 2008

When it comes to design and acquire underwater vehicles such as a submarine and a torpedo according to the process of SBA(Simulation Based Acquisition)/SBD(Simulation Based Design), it is necessary to predict the performance of interest precisely and to perform the test over and over again using the M&S(Modeling and Simulation) of the engineering and the engagement level. In this paper, we research the DEVS(Discrete Event System Specification) and DTSS(Discrete Time System Specification) formalism based standard model architecture for the underwater vehicle which can support both the heterogeneous level of the M&S(Engineering/Engagement) and the different system of the M&S(Discrete Event System and Discrete Time System). To validate this standard modeling architecture, we apply it to the submarine normal diving simulation.