• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1068-1071
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• 2017

The turbine exhaust system consists of a turbine flange, heat exchanger, exhaust duct and thrust nozzle. Heat exchanger is used for the launch vehicle because of the advantage of reducing the weight of the helium gas and the storage tank by using the heat exchanger pressurization method compared to the cold gas pressurizing method. Since the gas generator is combusted in fuel-rich condition, the soot is contained in the combustion gas. Hence, the heat exchanger should be designed considering the reduction of the heat exchange efficiency due to the soot effect. In addition, the uncertainty of the heat exchange calculation and the evaluation of the influence of the combustion gas soot on the heat exchange can not be completely calculated, so the design requirements must include a structure that can guarantee and control the temperature of the heat exchanger outlet. In this paper, it is described that the component allocation, the design method considering the manufacture of internal structure, the advantages of new concept of nozzle design.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.942-944
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• 2017

High-speed vehicles are subjected to complex loads, such as acoustic pressure from the engine at launch and aerodynamic heating and aerodynamic pressure during flight. A thermal protection system panel is required to protect internal systems such as the fuel tank of the vehicle from the external environment. This study defines analytical models for heat transfer and thermal structure characteristics of the thermal protection system panel. Furthermore, the study performed parameters analysis to achieve the thermal structural integrity and to make it lighter.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.757-762
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• 2010

Korean fishing boats have had appropriate hull forms for the safety, stability and convenience of fishing ability. However, Korean fishermen are recently concerned about the resistance performance and speed of Korean fishing boats, because the prices of fuel oil are gradually risen, also the exhausting of fish resources and the demand of high speed fishing boats are increased. Therefore, the necessity of the study on the improvement of resistance performance for Korean small coastal fishing boats is gradually increased. This study compares the hull form characteristics of Korean fishing boats with those of Japanese fishing boats, and the hull form of a representative Korean fishing boat is modified. From the modification of the hull form parameters for the Korean fishing boat, the improvement of resistance performances is evaluated. Moreover, the increase of resistance performances is also achieved from the modification of local characteristics for the hull form of the Korean fishing boat. A computational method and ship model tests in towing tank are used for the conformations of the improvement of resistance performance.

• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.813-818
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• 2007

There are the C.W.C and Towing Tank to the model-test equipments of the boat. A model testing of the high speed boat have a difficult in the performance verification because of very a small the scale-ratio of the ship-model and restricted by flow-velocity of the C.W.C and X-carriage velocity of the T.T. In general, the stepped hull boat is a high of fuel-efficiency because of the resistance reduction by a small wetted surface-area in correspond without stepped-hull boat. But It have a tendency to be bad the rolling performance by reduced stern wetted-area In this paper, the high speed stepped planning-boats with & without attached a stern body were performed to compare the effect of resistance and rolling performance by using sea model-test method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.24-29
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• 2004

In this paper, we summarize the results of free drop wind tunnel test, separation analysis and flight test in order to verify the safety during the separations of an external fuel tank and the LAU-131 rocket launcher from XKO-l. The wind tunnel test was conducted to show the safety in free drop of the stores and to gather the trajectory data for fine tune of MSAP(Multi-body Separation Analysis Program). The enhanced MSAP was then used to predict the trajectories of the stores with and without the ejector forces. A correlation of MSAP results for free drop case was also made to show the safety of jettison with the free drop type bomb rack. Moreover, the flight test was conducted. and its results were compared to analysis results. Finally, the safe jettison boundary was determined from the flight test.

• Journal of Microbiology and Biotechnology
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• v.32 no.10
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• pp.1325-1334
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• 2022

Global warming has accelerated in recent decades due to the continuous consumption of petroleum-based fuels. Cyanobacteria-derived biofuels are a promising carbon-neutral alternative to fossil fuels that may help achieve a cleaner environment. Here, we propose an effective strategy based on the large-scale cultivation of a newly isolated cyanobacterial strain to produce phycobiliprotein and biodiesel, thus demonstrating the potential commercial applicability of the isolated microalgal strain. A native cyanobacterium was isolated from Goryeong, Korea, and identified as Pseudanabaena mucicola GO0704 through 16s RNA analysis. The potential exploitation of P. mucicola GO0704 was explored by analyzing several parameters for mixotrophic culture, and optimal growth was achieved through the addition of sodium acetate (1 g/l) to the BG-11 medium. Next, the cultures were scaled up to a stirred-tank bioreactor in mixotrophic conditions to maximize the productivity of biomass and metabolites. The biomass, phycobiliprotein, and fatty acids concentrations in sodium acetate-treated cells were enhanced, and the highest biodiesel productivity (8.1 mg/l/d) was achieved at 96 h. Finally, the properties of the fuel derived from P. mucicola GO0704 were estimated with converted biodiesels according to the composition of fatty acids. Most of the characteristics of the final product, except for the cloud point, were compliant with international biodiesel standards [ASTM 6761 (US) and EN 14214 (Europe)].

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.391-399
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• 2022

Hydrogen is one of the energy carriers and has high energy efficiency relative to mass. It is an eco-friendly fuel that makes only water (H₂O) as a by-product after use. In order to use hydrogen conveniently and safely, development of production, storage and transfer technologies is required and attempts are being made to apply hydrogen as an energy source in various fields through the development of the technology. For transporting and storing hydrogen include high-pressure hydrogen gas storage, a type of storage technologies consist of cryogenic hydrogen liquid storage, hydrogen storage alloy, chemical storage by adsorbents and high-pressure hydrogen storage containers have been developed in a total of four stages. The biggest issue in charging high-pressure hydrogen gas which is a combustible gas is safety and the backfire prevention device is that prevents external flames from entering the tank and prevents explosion and is essential to use hydrogen safely. This study conducted a numerical analysis to analyze the performance of suppressing flame propagation of 2, 3 inch flame arrestor. As a result, it is determined that, where the flame arrestor is attached, the temperature would be lowered below the temperature of spontaneous combustion of hydrogen to suppress flame propagation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1071-1086
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• 2016

The safety of aircraft can be threatened by environmental factors, such as icing, turbulence, and lightning strike. Due to its adverse effects on aircraft structure and electronic components of aircraft, lightning strike is one of the biggest hazards on aircraft safety. Lightning strike can inject high voltage electric current to the aircraft, which may generate strong magnetic field and extreme hot spots, leading to severe damage of structure or other equipment in aircraft. In this work, mechanism of lightning strike and associated direct and indirect effects of lightning on aircraft were studied. First, on the basis of aircraft lightning regulations provided by Aerospace Recommended Practice (ARP), we considered different lightning waveform and zones of an aircraft. A coupled thermal-electrical computational model of ABAQUS was then used for simulating flow of heat and electric current caused by a lightning strike. A study on fuel tank, with and without lightning protection system, was also conducted using the computational model. Finally, electric current flow on two full scale airframes was analyzed using the EMA3D code.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.15-21
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• 2012

MTBE (Methyl tertiary-butyl ether) has been commonly used as an octane enhancer to replace tetraethyl lead in gasoline, because MTBE increases the efficiency of combustion and decreases the emission of carbon monoxide. However, MTBE has been found in groundwater from the fuel spills and leaks in the UST (Underground Storage Tank). Fenton's oxidation, an advanced oxidation catalyzed with ferrous iron, is successful in removing MTBE in groundwater. However, Fenton's oxidation requires the continuous addition of dissolved $Fe^{2+}$. Zero-valent iron is available as a source of catalytic ferrous iron of MFO (Modified Fenton's Oxidation) and has been studied for use in PRBs (Permeable Reactive Barriers) as a reactive material. Therefore, this study investigated the condition of optimization in MFO-PRBs using waste zero-valent iron (ZVI) with the waste steel scrap to treat MTBE contaminated groundwater. Batch tests were examined to find optimal molar ratio of MTBE : $H_2O_2$ on extent to degradation of MTBE in groundwater at pH 7 with 10% waste ZVI. As the results, the ratio of optimization of MTBE to hydrogen peroxide for MFO was determined to be 1:300[mM]. The column experiment was conducted to know applicability of MFO-PRBs for MTBE remediation in groundwater. As the results of column test, MTBE was removed 87% of the initial concentration during 120days of operational period. Interestingly, MTBE was degraded not only within waste ZVI column but also within sand column. It means the aquifer may affect continuously the MTBE contaminated groundwater after throughout the waste ZVI barrier. The residual products showed acetone, TBF (Tert-butyl formate) and TBA (Tert-butyl acetate) during this test. The results of the present study showed that the recycled materials can be effectively used for not only a source of catalytic ferrous iron but also a reactive material of the MFO-PRBs to remove MTBE in groundwater.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.4
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• pp.419-427
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• 2019

The application of ion crystallization technology was considered as a way to increase the operating efficiency and improve the operating performance of a liquid waste management system (LWMS) in the Advanced Power Reactor 1400 (APR 1400). Although ion crystallization technology has not been practically applied to Nuclear Power Plants (NPPs) until now, a previous experimental study demonstrated that it is possible to selectively remove at least 95% of various nuclide ions present in the liquid radioactive waste of NPPs. We reviewed the possibility of applying ion crystallization technology to the existing LWMS by applying the nuclide removal rate of ion crystallization technology and prepared a way to improve the existing LWMS in the APR 1400. Furthermore, we determined the optimized application location of ion crystallization technology in the existing LWMS by considering decontamination characteristics of the ion crystallization technology and the existing LWMS design features and operating experiences. The application of ion crystallization technology to the liquid waste collection tank, where liquid radioactive materials are collected, will have the least impact on the existing design while providing the greatest improvement. It is expected that the application of ion crystallization technology to the current APR 1400 or new NPPs would increase the operating efficiency of the LWMS and result in an improvement of system performance.