• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1040-1049
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• 2010

The strengthened regulations for atmospheric emissions from ships have caused a necessity of new, alternative power system in ships for the low pollutant emissions and the high energy efficiency. Recently, new kinds of propulsion power system such as fuel cell system, which use hydrogen as an energy source, have been sincerely considered. The purpose of this work is to predict the performance of methanol fueled SOFC/GT hybrid power system and to analyze the influence of operating temperature of stack, current density of stack, pressure ratio of turbine, temperature effectiveness of recuperator, turbine inlet temperature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.957-967
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• 2017

Firing test of the fuel grain for solid fuel ramjet with additives and ignition support material was conducted. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Boron particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. An oxidant gas having a controlled temperature, pressure and oxygen composition close to the air condition in the ramjet combustor was supplied using the Ethanol blended $H_2O_2$ gas generator. Gas was set to flow at a mass flow rate of 150 g/s and mass flux of $200kg/m^2s$ in the grain port. Through the test, ignition support operated well and ignition delay of 0.5. During the test, stable chamber pressure with 8 bar and high combustion efficiency of 0.86 was confirmed.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.61-70
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• 2008

This study was conducted to develop a mobile tower-yarder with tractor for agriculture and forestry that is the efficient yarder in steep terrains, thinning operation and small scale logging operation. It was designed and manufactured that the power source of tower-yarder is equiped three hydraulic pump connected to PTO of tractor, and three hydraulic pump is used to operate the four motor for drum, the cylinder for clutch of interlocker, the cylinder for tower expanding and the out-rigger cylinder. It was to adopt the running skyline system and the inter-lock function, and to equip the double capstan drum, the storage drum and the clutch for interlock in the development of tower-yarder. It was to develop the tower-yarder which the winch torque of double-capstan drum, the traction force of double-capstan drum, the number of rotation of double-capstan drum and the line speed is $191kg{\cdot}m$, 1,910 kgf, 220.5 rpm and 138.5 m/min, respectively. And it was known that the optimum flange diameter of the main and haulback storage drum is about 360 mm and about 460 mm in order to storage the main line length of 250m and the haulback line length of 450 m. The carriage was made to adopt the running skyline system and to equip the lock function in order to the convenience of chocking and the fall down preventing of tree. It was provided to develop the wire remote controller for the inter-lock function, the convenience of control and the efficiency of yarding. In development process, this tower-yarder was attached the 3-point linkage hitch equipment and the tire wheel for the traction and moving of tower-yarder. Also, it was equipped that the out-rigger and the guy line in order to raise the safety and efficiency of yarding of tower-yarder.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.4
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• pp.317-324
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• 2015

In this study, a solar thermal system is designed to provide hot water and electricity for improvement of solar thermal energy availability in an apartment complex. The electricity is generated with Organic Rankine Cycle (ORC) by the solar thermal energy. R134a, R141b and R245fa are selected for operating fluid of the solar thermal ORC system. ORC with R245fa shows the best performance based on the variation of pressure. The irreversibility of component showed that the technology advance of the evaporator ensures a performance improvement. The sensitivity study results indicate that the turbine performance is most effective way to improve the performance of ORC system. An economic analysis showed that approximately 50% more income could be achieved by a solar thermal ORC system with a hot water supply.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.729-736
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• 1997

For the recovery of industrial waste heat, a chemical heat transformer based on the reversible reaction between metal chlorides and ammonia gas was designed and a pilot scale unit of 1 kW-1hr was developed. A static calculation, which determined the amount of reacting materials and operating condition of system, and dynamic simulations were performed for the optimal design. The temperature and output power of generator in the system were varying with the amount of salt and heat exchange area. Optimum conditions such as the amount of salt-graphite, apparent density and size of mechanical unit were determined by the dynamic simulation for the system. According to the operating cycle of 4 stages, experimental results of temperature and output power were well agreed with the simulation values. This chemical heat transformer is turned out to be a very promising system for recovery of industrial waste heat because of its effective feature of lifting temperature.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.156-164
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• 2016

Qualification model(QM) of main payloads including concentrating photovoltaic system using fresnel lens, heating wire cutting type shockless holding and release mechanism, and MEMS-based solid propellant thruster have been developed for the STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project), which is a pico-class satellite for verification of core space technologies. In this study, we have verified structural safety and functionality of the developed payloads under a qualification temperature range through the QM thermal vacuum test. Additionally, a reliability of thermal model of the payloads has been confirmed by performing a thermal correlation based on the thermal balance test results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.114-122
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• 2002

The integration of the landing gear system is a complex relationship between the many conflicting parameters of shock absorption, minimum stow area, complexity, weight and cost. Especially ground impact load and dynamic behaviors greatly influence design load of landing gear components as well as load carrying structural attachment. This study investigates ground impact load and dynamic behaviors of the T-50 landing gear system using ADAMS. Taking into account for various operational/environmental conditions, an analysis of shock absorbing characteristics at ground impact is performed with experience derived from a wide range of proprietary designs. Analytical results are presented for discussing the effects of aircraft horizontal and vertical speed, landing attitudes, shock absorbing efficiency. This analysis leads us to the conclusion that the proposed program is shown to be a better quantitative one that apply to a new development and troubleshooting of the landing gear system.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.63-70
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• 2023

In this work, a capacitive wireless power transfer (C-WPT) system is presented for wireless sensor system (WSS) applications in marine propulsion shafts. For a single Q factor on both sides of the coupling capacitor and reactive power removal from the circuit, a double-sided LCLC converter and transformers topology are designed to drive the rotary C-WPT system for WSS on the shaft. Parallel-connected parallel plate rotating capacitors with a capacitance of 170 pF are designed and implemented for the C-WPT system on a snow rotating shaft. In the experimental results, the C-WPT system achieved a transmission efficiency of 66.67% with 7.8 W output power at 3 mm distance and 1 MHz operating frequency. Therefore, it was proved that the fabricated C-WPT system can supply power to the WSS of the rotating shaft.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.53-63
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• 2024

Adopting an engine igniter with high efficiency and ignition performance is essential for reliable operation of liquid rocket engines. In this study, we developed a spark torch igniter for a 450 N-scale methane-oxygen liquid rocket engine by conducting numerical analyses, igniter manufacturing and validation. Specifically, we conducted a parametric study for maximizing the enthalpy at the igniter exit, specifically by adjusting the mass flow rate, nozzle area ratio, fuel-oxidizer mixture ratio, and the igniter length-to-diameter. The heat transferred via the igniter nozzle exit was computed using 3-dimensional numerical simulations. We also manufactured and tested the igniter based on a deduced design to confirm ignition performance of the designed spark torch igniter. The igniter developed through this study could contribute to the development of practical propulsion systems such as upper-stage engines of small launch vehicles.

• Membrane Journal
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• v.10 no.2
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• pp.83-91
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• 2000

In order to improve functional properties, enzymatic hydrolysis of FPC (fish protein concentration) was achieved in ultrafiltration membrane reactor (MWCO 5,000). First, insoluble FPC was hydrolyzed by pepsin in batch reactor to decrease the fouling in ultrafiltration membrane reactor, and second hydrolysis was achieved by pronase E in ultrafiltration membrane reactor The optimum operating conditions in batch reactor using pepsin were at temperature 45$^{\circ}C$, pH 2.0 and the ratio of substrate to pepsin, 150 (w/w) After operating for 5hrs under optimum conditions, 89％ of total amount of initial FPC was hydrolyzed. The rate constants, $K_{m}$ and V$_{max}$, were 1.25％ and 0.89 mg/$m\ell$/min, respectively, and substrate inhibition was occured above 1.5％. The ultrafiltration membrane reactor was operated with recycling rate of 474 $m\ell$/min and transmembrane pressure of 15 psi. The permeate flux was increased by temperature, transmembrane pressure, but the permeate flux was fixed by pH. The optimum ratio of substrate to pronase E was 200(w/w) and the productivity of ultrafiltration membarane reactor was 702 mg/mg -enzyme, that of batch reactor was 51mg/mg-enzyme. Molecular weight distributions tot first and second hydrolysates were from 2,500 Da to 20,000 Da and from 700 Da to 10,000 Da, respectivelyly.