• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.485-490
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• 2010

MILD (Moderate and Intense Low Oxygen Dilution) combustion is a technique which is able to reduce NOx formation and to uniform temperature distribution in the furnace by recirculating the exhaust gas to the fresh air and fuel. This study focuses on finding optimal condition of MILD combustor by changing equivalence ratio with fuel and air flow. The present experiment employs six thermocouple sensors in the furnace, and two concentration probes of NOx and CO at the exhaust exit pipe respectively. The MILD combustion phenomena have been observed at the condition of equivalent ratios of 0.71~0.73, and the temperature uniformity, NOx and CO concentration are also examined at the MILD combustion condition.

• Fire Science and Engineering
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• v.26 no.2
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• pp.53-58
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• 2012

In this study fire control characteristics for inflammable materials of water curtain system are experimentally analyzed. Heat release rate for pinewood and gasoline was calculated using Room Corner Tester (RCT) and fire test apparatus for water curtain system is manufactured. Nozzles (180 degree of injection angle, 8.2 mm of orifice diameter) are installed at the nearby ceiling of place at 5 m distance from fire originate and temperature profile as well as transmission are obtained from the fire experiment of pinewood and gasoline in the water curtain system. Based on the results, parameters of engineering importance for fire control characteristics of water curtain system such as generation of high temperature smoke and thermal phenomena of fluid flow by injection nozzle are identified.

• Fire Science and Engineering
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• v.25 no.3
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• pp.51-56
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• 2011

The full-scale experiments are carried out to investigate the fire suppression characteristics of water-based fire fighting systems in a road tunnel. Applied systems are the low-pressure water spray system at 3.5 bar and the high-pressure water mist system at 60 bar. The water flow rate of the high-pressure system is one sixth only of the water spray system. A passenger car and a heptane fuel pan with area of $1.4m^2$ are used as fire sources. A blower system is installed at the tunnel exit to realize the longitudinal ventilation conditions (0.9~3.8 m/s) in the tunnel. Temperatures from the fire source to the down-stream direction are measured by K-type thermocouple trees. The experimental results show that the cooling effect of the high pressure water mist system in the test conditions were equivalent to that of the low pressure water spray system for B-class fire.

• Journal of Navigation and Port Research
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• v.28 no.5
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• pp.365-372
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• 2004

LNGC suffers a great heat inflow during navigation and this heat inflow inevitably boils off the LNG. The boiled off gas(BOG) is normally consumed as a fuel for ship's engine. The boiled off LNG means a loss of cargo during transportation in the viewpoint of shipper. Therefore, a contract between shipper and ship operator is made for the limitation of BOR under 0.15 ％/day based on laden voyage. This contract on BOR limit requires that ship's officer has a correct knowledge on BOR for his ship. nut, in most cases ship IS operated based on only officer's experiences. In this study, author presented a simple model to predict the BOG during navigation based on the existing precision heat exchange design technology about the heat distribution on the hull and heat inflow from outside through the hull. The BOG is calculated for ballast and laden voyage based on the actual weather conditions and verified by comparing with the measured BOG for the study ship. The study ship is a membrane type LNGC which is now servicing in Middle east route. Thus, the BOG prediction method which is presented in this study is expected to be used for an useful tool to manage the BOG in now servicing LNGC.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1257-1264
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• 2011

This paper presents 3D simulation by STAR-CCM+ for lean premixed combustion in a stationary gas turbine combustor with separate pilot and main nozzles. The constant for the source term in the flame area density transport equation was modified to account for a low global equivalence ratio and validated against measurement data. A Partially-premixed Coherent Flame Model(PCFM) involves propagation of a laminar premixed flame with the predicted flame surface density and equilibrium assumption in the burned gas with spatial inhomogeneity. The conditions for cooling by radiation and convection are considered for accurate determination of the heat flux on the wall. A parametric study is of the pilot-fuel-to-total-fuel-ratio is carried out. A chemical reactor network (CRN) was constructed on the basis of the 3D simulation results and compared against measurements of NOx.

• Fire Science and Engineering
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• v.14 no.3
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• pp.27-32
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• 2000

The assessment of wildland fire hazard is the first priority to be considered in the prevention, extinction and control of wildland fire. For the standard to measure wildland fire hazard, the wildland fire Warning System is currently being used in Korea which computes the wildland fire occurrence hazard index through a stick weight to moisture conversion formula. It shows the risk of fuel substance being exposed to fire by meteorological factors. For a comprehensive assessment of wildland fire hazards by area, the major factors'hazards need to be measured and the assessment of wildland fire needs to be conducted through historical statistic examination. Therefore, the wildland (ire outbreak frequency and its seriousness of damage are analyzed through historical statistic examination to conduct the assessment of a wildland fire hazard, and then the calorific value of a forest is analyzed through differential scanning calorimeter measurement which assesses the comparative calorific hazard according to the geographical distribution of vegetation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.82-88
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• 2006

In order to effectively reduce thermal loads on regenerative cooled walls, fuel cooling injectors and film cooling devices have often been employed. The present study has established a numerical methodology for prediction of performance and near-wall temperature distribution taking into account the nonuniform mixing due to these additional cooling devices. A correction procedure for main propulsive parameters has also been proposed based on comparison between prediction and experimental data. Under the computational framework of this study, the predicted results were in good agreement with hot-firing test data for a 30 tonf-class full-scale combustor at the design and off-design conditions. As a consequence, the present numerical method is expected to be useful for design and evaluation of regenerative cooled liquid rocket thrust chambers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.258-261
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• 2003

The optimal design and combustion analysis of the gas generator for Liquid Rocket Engine (LRE) were performed. A fuel-rich gas generator in open cycle turbopump system was designed for 101on1 in thrust with RP-1/LOx combination. The optimal design was done for maximizing specific impulse of main combustion chamber with constraints of combustion temperature and power matching in turbopump system. Results of optimal design show the dimension of length, diameter, and contraction ratio of gas generator. The configuration of the gas generator and the condition for performance which can maximize the objective function were determined and found to meet the design constraints. Also, the combustion analysis was conducted to evaluate the performance of designed chamber and injector of gas generator. And the effect of the turbulence ring was investigated on the mixing enhancement in the chamber.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.8
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• pp.815-823
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• 2011

Combustion phenomena in porous media combustors are widely used in industrial fields for the combustion of lowgrade fuels and the regeneration of combustion heat. However, studies of combustion phenomena in porous media have been limited, because these phenomena are difficult to observe, and the configurations of porous media are complex. We propose a simple model combustor: a multi-channel combustor that consists of many layers of combustion channels made of quartz plates. We conducted an experimental observation of the flames in the multi-channel combustor and obtained experimental results for the flame stabilization limits. Flames formulated in the multi-channel combustor showed variation in the spatial distribution depending on the heat transfer between neighboring channels. A simple analytical model was developed and the variation in the flammability limits of the multi-channel combustor was discussed. This study will enhance our understanding of flame behavior in a porous-media combustor.

• Nuclear Engineering and Technology
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• v.15 no.4
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• pp.267-279
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• 1983

An analytical system has been established for scrutinizing both uranium- and plutonium-fueled lattices moderated by light water. This system consists of two primary codes. One is a unit cell program called KICC, which has theoretical foundation on the models of GAM and THERMOS incorporated with appropriate approximate treatments for various phenomena, whereas the other is a multi-dimensional diffusion-depletion program entitled KIDD. The adequacy of this system is verified by performing extensive benchmark calculations on a variety of critical experiments. The average value of effective multiplication factors for the selected nineteen UO$_2$ critical experiments of heterogeneous lattice structure is calculated to be 1.0006 with a standard deviation of 0.0039. Power distributions have also been calculated for some critical experiments fueled with both uranium and plutonium of varying concentrations. The maximum percentage difference between the measured and calculated power distributions appears to be less than 5%. This result, together with the previously reported result, illustrates that the KICC/KIDD system is a very effective tool for the analysis of a light water reactor core.