• Journal of Environmental Science International
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• v.16 no.1
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• pp.9-19
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• 2007

Comparing predicted PCDF isomer patterns with those obtained from a municipal waste incinerator assessed the role of two-phenol condensation pathways in the formation of PCDFs. Complete PCDF homologue and isomer distributions were obtained from a Fluidized Bed Incinerator (FBI). Two-phenol condensation model, dependent only on the distributions of phenols, was developed to predict the PCDF congeners produced from phenol precursors. R-squared values from linear correlations are presented for the dichlorinated through hexa-chlorinated isomer distributions between measured and predicted. They range from 0.00: to 0.1 far the di-chlorinated through hexa-chlorinated isomer sets. Agreement between predicted and measured PCDF isomer distributions was very poor for all homologues. Two-phenol condensation pathways are not likely to be the pre-dominant pathways in the formation of PCDF in a FBI. However, dibenzofuran (DF) is likely to be produced from a condensation of two phenols. This work demonstrates the use of PCDF homologue and isomer patterns for testing PCDF formation mechanism from two-phenol condensation pathways in municipal waste incinerators.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.363-368
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• 2015

Finding an alternative fuel and reducing environmental pollution are the main goals for future internal combustion engines. The purpose of this study is to obtain low-emission and high-efficiency by hydrogen enriched LPG fuel in a LPG engine. An experimental study was carried out to obtain fundamental data for the emit HC emission characteristics at cold start of pre-mixed LPG and hydrogen in a LPG engine with various fractions of hydrogen-LPG blends. To maintain equal volume ratio of fuel blend, the amount of HC was decreased as hydrogen was gradually added. The results showed that as hydrogen increases, in-cylinder pressure increased. Also emission of unburned hydrocarbon (HC) is sharply decreased.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.32-40
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• 2017

The current status of Performance-Based Design (PBD) implemented in 4 wide areas (Seoul, Gyeonggi, Incheon and Busan) over the past 5 years was reviewed with regard to the number of PBD implementation and target buildings. Then, detailed status related to fire scenarios, input information for fire simulation, and grid size were analyzed with the pre-review for the PBD. As a result, the domestic PBD was mainly applied to the mixed occupancy. In the fire simulations performed on the identical fire scenario and fire space, the maximum heat release rate (HRR) varied significantly depending on the PBD designer. Various combustibles were also considered for the identical fire source, and their combustion properties also showed considerable uncertainty. In addition, the applicability of accurate input information for predictive models of heat and smoke detectors was examined. Finally, the average grid size for the fire simulation using Fire Dynamics Simulator (FDS) was analyzed, and the improvement of PBD to minimize designer dependency was proposed.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.28-35
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• 2017

A main oxidizer shutoff valve controls the supply of the oxidizer flow into the combustion chamber of a liquid rocket engine. This shutoff valve also carries out the pre-chilling of oxidizer supply lines by permitting recycling flow for stable transient start of the engine. In the present paper, the flow tests for the recycling line of the valve were conducted in order to evaluate the cooling performance of the main oxidizer shutoff valve. In addition, cryogenic life-cycle tests were performed with an assumption of the increase of spring constant with increasing valve operating times due to ductile-brittle transition effects.

• Korean Journal of Computational Design and Engineering
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• v.13 no.5
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• pp.372-381
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• 2008

We developed a design automation system to reduce the lead time and help engineers in designing a solid fuel, or a grain, for rocket missiles. First, we analyzed design activities and shapes of a grain, which resulted in the standard of design process and shape. We decided development process which consisted of two typical activities such as constructing master library and implementing design system. We constructed some master models for typical external shapes and core shapes of grains which were used in modeling the shape of a designing grain. Also we implemented a design automation program to use the master models according to the pre-defined design process. It can calculate some design parameters such as mass, mass center, volume and combustion area that are used in analyzing a proposed grain. Finally, we could reduce the design time dramatically and increase design quality by automating many routine and difficult works.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.517-520
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• 2017

In this paper, we represented the structural design parameter effect on the sealing gap behavior of solid rocket motor case and nozzle connection under penetrated pressure through the sealing path between insulation rubber and the ablative FRP bonded on the inside convergent wall of nozzle. It is important to keep the good sealing capacity during all the combustion time of SRM. To achieve the crucial role of sealing system of SRM, designers must consider design factors for stable sealing clearance gap as the nearly unchanged initial design state as possible for sufficient compression rate of O-ring under sealing gap pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.277-284
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• 2017

This study is the results of the analytical research for a dual-model scramjet engine flowpath which is included inlet, isolator, combustor, and nozzle. To design a dual-mode scramjet engine and to investigate its performance, the performance analysis models and tools are required to develope for aerodynamic, thermodynamic characteristics, propulsion, and total system. Therefore, analysis models for air inlet, isolator, supersonic combustor, and nozzle of a dual-mode scramjet engine were accomplished, the performance characteristics of a dual-mode scramjet engine is investigated with using the developed analysis tools.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.133-140
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• 2014

The experiment was designed to compare the char combustion kinetics of pulverized Indonesia coals commonly utilized in Korea power plants. The reaction rate of coal char has been formulated using the external and internal effectiveness factors to describe the diffusion effect quantitatively. The Random Pore Model (RPM) was used for applying internal specific surface area as a function of carbon conversion ratio. Reaction rate was obtained from reaction time using the Wire Heating Reactor (WHR) which can heat and measure the char particle temperature at the same time. BET and TGA were used to obtain physical properties such as internal specific surface area and structural parameter. Three kinds of Indonesia Sub-bituminous coals "BARAMULTI, ENERGYMAN, AGM" were used in order to derive the activation energy and pre-exponential factor. The results of this study showed that the effect of internal diffusion than that of external diffusion is the dominant as comparison of kinetics was reflected in external and internal effectiveness factors. For three kinds of coal char, finally, activation energy of intrinsic kinetics indicates 110~118 kJ/mol.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.676-682
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• 2009

Devolatilization of the Refuse Derived Fuel(RDF) which is produced at WonJu in Korea was characterized in air atmosphere with variation of heating rate(10, 20 and $30^{\circ}C/min$) in TGA. The results of TG Analysis have shown that the pyrolysis and char combustion of the RDF occurred in the range of $350{\sim}700^{\circ}C$ depending on the heating rate. Activation energy of the RDF which was determined by using Friedman and Ozawa-Flynn-Wall method was in the range of 14.44~18.40 kcal/mol. Also, reaction order(n) and pre-exponential factors(A) were 1.219 and $3.02{\times}10^5$ by using Friedman method, respectively. In order to find out the devolatilization mechanism of the RDF, twelve solid-state mechanisms defined by Coats Redfern Method were tested. The results of the Coats Redfern Method have shown that chemical reaction is the effective mechanism by comparison with the value of the activation energy which was derived from the Friedman and Flynn-Wall-Ozawa method and correlation coefficient from twelve solid-state mechanisms of Coats Redfern Method. The solid state decomposition mechanism of the RDF was found to be a decelerated $F_1$ type, random nucleation with one nucleus on the individual particle.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.154.1-154.1
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• 2010

석탄가스화복합발전(IGCC)에서는 석탄을 가스화하여 얻어진 합성가스로부터 이산화탄소를 분리/회수하고 수소는 유용하게 사용할 수 있다. 이 기술의 핵심은 $H_2+CO_2$ (40%) 합성가스로부터 $CO_2$를 경제적이고 효과적으로 분리/회수하는 것이다. 본 연구에서는 합성가스로부터 $CO_2$를 효과적으로 분리/회수하기 위해 가스 하이드레이트 형성법을 제안하였다. 하이드레이트 형성 조건을 완화시켜 주기 위하여 열역학적 촉진제로서 TBAB, TBAF, THF를 첨가하여 열역학적 촉진 현상을 살펴보았다. 다양한 농도의 TBAB (10, 40, 60 wt%), TBAF (10, 34, 45 wt%), THF (4, 19, 31 wt%)에 대하여 3상 평형 (하이드레이트 (H) - 물 (LW) - 기상 (V))을 측정한 결과 40 wt%의 TBAB, 34 wt%의 TBAF, 19 wt%의 THF의 농도에서 가장 큰 촉진효과를 보였으며, 그 이상의 조성에서는 오히려 촉진효과가 줄어드는 것을 확인할 수 있었다. 순수계와 촉진제 첨가계에 대하여 하이드레이트 생성 후의 기상과 하이드레이트상의 $CO_2$ 조성을 측정하였다. 그 결과 모든 실험조건에서 하이드레이트상에 85% 이상의 높은 농도로 $CO_2$가 농축되는 것을 확인하였다. 이러한 과정을 반복하면 순도 99% 이상의 매우 높은 $CO_2$ 기체를 얻을 수 있다. 또한, 가스 하이드레이트 형성과정의 반응특성을 살펴보기 위하여 반응시간에 따른 기상의 $CO_2$ 농도변화를 측정하였다. 본 실험에서 얻어진 결과는 가스 하이드레이트 형성법을 이용한 합성가스 분리 공정 개발에 중요한 기초자료가 될 것으로 사료된다.