• Fire Science and Engineering
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• v.25 no.5
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• pp.62-68
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• 2011

A series of fire tests involving realistic solid combustible materials was conducted to quantify the heat release rate and investigate the fire growth characteristics during the initial fire growth stage. For these tests, single/double wood cribs, urethane cushion having polypropylene covers and wood crib on nylon carpet with urethane carpet padding were used as a fuel source. The fire growth coefficient of the solid combustible materials was quantified and the fire growth characteristics were compared with the $t^2$ fire scenario. The mean effective heat of combustion was evaluated by the total mass loss of fuel and total energy release concept and examined the effect of the ventilation and fire condition. The present study provides the practical information on the fire growth characteristics of solid combustible material to design to a set of fire scenarios for the fire risk analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.7
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• pp.647-653
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• 2013

The evaporation characteristics of nanofluid droplets on a heated solid surface were experimentally investigated. The experiments were conducted using pure water and a nanofluid of water mixed with CuO nanoparticles, and the solid surface was made of a copper block heated by a nine cartridge heater. The experimental results showed that the evaporation rate of the nanofluid droplet was higher than that of the pure water droplet on the heated solid surface because nanoparticles increased the thermal conductivity of the nanofluid. Furthermore, it was found that the evaporation rate of the nanofluid droplet increased with the solid surface roughness. This may be because the actual area of the liquid-solid interface increased with the solid surface roughness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.286-290
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• 2008

This paper summarizes the components of an explicit aeroelastic solver developed especially for the simulation of dynamic fracture events occurring during the flight of solid propellant rockets. The numerical method combines an explicit Arbitrary Lagrangian Eulerian (ALE) version of the Cohesive Volumetric Finite Element (CVFE) scheme, used to simulate the spontaneous motion of one or more cracks propagating dynamically through a domain with regressing boundaries, and an explicit unstructured finite volume Euler code to follow the flow field during the failure event. A key feature of the algorithm is the ability to adaptively repair and expand the fluid mesh to handle the large geometrical changes associated with grain deformation and crack motion.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.109.2-109.2
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• 2011

바이오디젤의 생산은 원료유의 순도와 촉매 종류, 알코올의 양, 반응시간, 반응 온도와 같은 다양한 조건을 이용하여 최적의 조건을 찾아내는 것이 중요하며 이는 곧 생산단가와 직결된다. 바이오디젤 전환 시 고체촉매를 이용하면 후처리 공정의 단순화가 가능하며 글리세린의 순도가 약 98%로 매우 높아져 고부가 물질 생산 원료로 활용이 가능하다는 장점이 있으며 생산 단가를 4~20% 가량 낮출 수 있다. 본 연구에서는 바이오디젤의 경제적인 생산을 위하여 정제공정을 단순화 시킬 수 있는 방안으로 3종의 고체촉매를 이용하여 동 식물성 유지의 바이오디젤로 전환 실험을 수행 하였다. 촉매 활성화를 위하여 고체촉매를 $700^{\circ}C$에서 3~5시간 소성하고 동 식물성 유지를 이용 전이에스테르화 반응실험을 수행하여 30분 간격으로 시료를 수집 하였다. 실험 결과, 동물성 폐유지로부터 반응 120분 후에 최대 90% 이상의 지방산 메틸에스테르로의 전환율을 얻을 수 있었으며 식물성 유지인 팜유에서는 86%, 유채유에서는 64%의 전환율을 나타냈다. 동 식물성 유지의 초기 산가는 0.45~2mg KOH/g 사이로 나타났다.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.48-56
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• 2011

A Possibility of combustion instability on longitudinal mode has a high level at large scale of L/D. Solid propellant has a metal particle and a grain of control to pressure oscillation. Solid rocket motor in slotted-tube grain controls pressure oscillation of longitudinal mode. Slotted-tube grain restrains longitudinal 1st pressure oscillation. But cavity volume of aft. insulation ablation amplifies 2nd pressure o scillation by vortext shedding. A study has suppressed combustion instability and vortex shedding by modified 4 slotted tube solid rocket motor design.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.1
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• pp.36-43
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• 1988

A two phase model for the simulation of flame propagation has been developed and applied to a mixture of coal air. The effects associated with changes in the initial coal partial equivalence ratio and the initial diameter of particles on the structure of laminar flame propagation have been studied qualitatively and quantitatively. Especially the flame structure, the burning velocity, and the thermal behavior were evaluated. It was found that the radiative heat transfer absolutely dominates over the conduction mode. The increase in particle size was seen to contribute to an obvious increase in burning velocity for fuel lean and stoichiometric mixture. But for fuel rich mixture, the burning velocity was found to exhibit a weaker dependence on particle size.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.733-738
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• 1998

본 논문에서는 고체 리듐 전지를 개발하기 위하여 poly(ethylene oxide) [PEO] 에 $LiClO_4$, poly (vinylidene fluoride) [PVDF] 및 가소제로 propylene carbonate [PC] 와 ethylene carbonate[EC] 등을 혼합여 고분자 저해질을 제조하였다. 또한 고체 리듐 전지용 정극으로써 우수한 특성이 기대되는 $Li_xV_3O_8$을 졸-겔법에 의해 합성하여 $Li_xV_3O_8$SPE/Li cell 의 전기화학적 특성을 측정하였다. 고분자 matrix는 PEO와 PVDE를 혼합 사용한 결과 $PEO_4 PVDF_4LiCIO_4PC_5EC_5$ 고분자 전해질이 상온에서 $5.2 {\times} 10{-3}$ S/cm 의 높은 이온 전도도를 나타냈으며 리듐 이온 transference number는 0.3이었다. 졸-겔법에 의해 제조된 $Li_xV_3O_8$을 사용한 $Li_xV_3O_8$SPE/Li cell의 방전시 cell 저항이 방전 초기에는 비소한 증가를 하다가 방전 말기 전압인 2.0V에서 크게 증가하였다. $Li_xV_3O_8$ composite 정극의 첫 번째 방전 용량은 295㎃h/g이었으며 8번째 충방전 싸이클부터 방전 용량이 안정화 되었고 15번째 방전 용량도 212㎃h/g으로 고체 전지용 정극으로써 우수한 특성을 보였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.1
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• pp.59-66
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• 1998

The combustion instability analysis of solid propellants is generally done by the simplified governing equations for chemically inert condensed phase region with QSHOD assumption. Since the gas phase and surface reaction layer can be more rapidly relaxed to the external perturbations than the condensed phase, these regions are treated as quasi-steady manner in the analysis. In this paper, the classical ZN(Zeldovic-Novozhilov)approach was re-examined with the presence of radiation augmented burning enhancement in the combustion. Also, the surface reaction was assumed to partially absorb the incident radiant heat fluxes and pass the remaining to the chemically inert condensed phase. As a result of the analysis, the burning rate response function was obtained which consists of a pressure response function and a radiation response function. The response function was shown to be able to predict the results of T-burner tests.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.21-26
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• 2019

Exposure to a rapidly depressurized environment causes extinction of a burning solid propellant. Experiments have been conducted to determine the rate of depressurization required to extinguish a burning solid propellant. For this purpose, a depressurization combustor was designed and fabricated. The results of this experiment were used to determine the boundary between extinction and non-extinction of AP/HTPB solid propellants under different propellant compositions. Experimental results show that the initial and final pressures have a considerable effect on the critical depressurization rate.

• Clean Technology
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• v.17 no.1
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• pp.62-68
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• 2011

Hydrodynamic characteristics in multistage annular type fluidized bed (riser: $0.01{\times}0.025{\times}2.8m^3$, J-valve: $0.009{\times}0.015m^2$)were investigated. Glass beads ($d_p=101{\mu}m$, ${\rho}_b=1,590kg/m^3$, $U_{mf}=1.25{\times}10^{-2}m/s$, Geldart classification B) was used as a bed material. Accumulated weight by the electronic balance was measured to determine the solid flow rate in batch-type. In circulation condition, we measured the accumulated weight of particle transported from riser. At the steady state condition, solid circulation rate was calculated from time interval of the heated bed material passing between two thermocouples. Solid flow rate increased with increasing inlet gas velocity ($1.2-2.6U_{mf}$) and the static bed height (z, 0.24-0.68 m) from 2.2 to 23.4 kg/s. However, mean residence time decreased with increasing inlet gas velocity ($1.2-2.6U_{mf}$) and the static bed height (z, 0.24-0.68 m) from 1,438 to 440 s. The solid holdup in the riser was determined by measuring pressure differences according to the riser height. These results showed a similar trend to that of simple exponential decay type except for the top section of the riser. To verify the gas bypassing from top bubbling beds to middle bubbling beds, $CO_2$ gas was injected by tracer gas in constant ratio, and then was measured $CO_2$ concentration in outlet gas by gas chromatography. Gas bypassing occurred below 2.6% which is negligible value.