• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.5
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• pp.509-515
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• 2012

In this study, ${\gamma}-Al_2O_3$ nanoparticles were synthesized by using coflow hydrogen diffusion flames. The synthesis conditions were varied with using several oxygen concentrations in the oxidizing air. The particle characteristics of the flame-synthesized $Al_2O_3$ nanoparticles were determined by examining the crystalline structure, shape, and specific surface area of the nanoparticles. The measured maximum centerline temperature of the flames ranged from 1507.8 K to 1998.7 K. The morphology and crystal structure of the $Al_2O_3$ nanoparticles were determined from SEM images and XRD analyses, respectively. The particle sizes were calculated from measured BET specific surface areas and ranged from 25 nm to 52 nm. From XRD analyses, it was inferred that a large number of the synthesized nanoparticles were ${\gamma}-Al_2O_3$ nanoparticles including ${\theta}-Al_2O_3$ nanoparticles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.04a
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• pp.2-2
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• 1998

현대우주항공(주)가 미국의 AlliedSignal사와 함께 국제 공동 개발중인 10MW급의 ASE120 엔진은 항공용 엔진을 산업용으로 개조한 개조형 엔진으로서 희박 예혼합 예기화(Lean Premix prevaporization) 방식의 연소기를 쓰고 있다. 이 연소기는 연소에 관여하는 공기량을 부하에 따라 가감하여 일정 공연비를 유지하는 air staging법을 사용하고 있으며 이로써 연소화염온도를 일정치로 조절하여 연소중 생성되는 유해가스의 양을 목표치 이하로 제어한다. 연소화염온도 설계치는 2912$^{\circ}$F이며 배기가스 발생량은 NOx, CO모두 궁극적으로 10ppmv 이하를 목표로 하고 있다. 이러한 건식 저 배기가스(Dry Low Emission) 연소기가 그 역할을 다하기 위하여는 양호한 혼합기를 확보하는 것이 선결 문제이다. 본 연구소에서는 두 개의 혼합기(mixing can)가 180$^{\circ}$ 간격으로 환형 연소기(annular type)에 접선 방향으로 설치되어 대칭을 이루고 있고 혼합기의 혼합성능을 측정하기 위하여 제작된 시험장치에는 하나의 혼합기만을 쓰고 있다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.513-519
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• 2009

현재 국내의 주요 샌드위치패널 화재안전성능 평가방법에는 Cone calorimeter (연소성능) 및 가스유해성 시험방법이 있지만 샌드위치패널의 경우 불연재질 속 심재의 연소특성을 측정하여 실제 화재에서의 연소거동을 예측하기가 쉽지 않다. 따라서, 본 연구에서는 스티로폼 패널의 화재 안전성 연구를 위해서 ISO 9705 시험(Room Corner Test)을 실시하였다. 실험결과 두 시편 모두 시험이 진행되고 약 12분 정도, 버너의 열량이 100 kW에서 300 kW로 진행되는 시점에서 천정부가 붕괴되어 스티로폼 샌드위치 패널의 구조적인 문제점이 발생되었다. 스티로폼 샌드위치 패널은 내부 심재에 화염이 전파되었을 경우 급속한 화염의 전파 속도로 인해 구조적인 문제점을 발생되는 것을 확인할 수 있었으며, 향후 이와 같은 스티로폼 샌드위치 패널의 실물 화재 시험에 따른 연구 결과들이 화재안전 성능 등급 분류 기준 설정에 사용될 수 있을 것이다.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.1-8
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• 2005

The effect of coolants has been studied on the burning properties of low burning rate HTPB/AP composite propellant containing Oxamide or Melamine as coolant for the gas generator. With increasing the content of coolant, the burning rate and the flame temperature could be lowered and the effect on flame temperature was about the same for two coolants. However due to the different thermal decomposition properties of coolant, the burning rate of Melamine propellant was found to abnormally decrease if $200{\mu}m$ AP was partially replaced with $6{\mu}m$ AP.

• Food Science and Preservation
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• v.18 no.3
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• pp.423-428
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• 2011

Inactivation kinetic data of Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Salmonella Typhimurium, and Salmonella Enteritidis via treatment with aqueous chlorine dioxide treatment at a specific concentration were evaluated using the first-order kinetic and Weibull models. The Weibull model showed a better fit with the kinetic data than the first-order kinetic model. The survival curves after the aqueous chlorine dioxide treatment showed $t_R$ values(time required to reduce microbial populations by 90%) of 2.49 min for E. coli O157:H7 at 5 ppm, 1.47 min for L. monocytogenes at 5 ppm, 0.94 min for S. aureus at 5 ppm, 0.87 min for S. Typhimurium at 1 ppm, and 0.08 min for S. Enteritidis at 1 ppm, according to the Weibull model.

• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.493-499
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• 2022

This paper reports the results of the eruption of a volcano on Jeju Island at a certain rate, and the tumulus formed after the eruption and the basalt that erupted from the middle of Mt. Halla washed up to the sea. We analyzed the speed when basalt underground magma breaks through the neutral zone on the ground with an absolute temperature of about 1000K and explodes at an absolute temperature of 1200K at an altitude of 1950m. The density of combustion gas becomes smaller than the surrounding air due to the plume volcanic eruption, which is the heat flow of the flame column due to buoyancy, and buoyancy is generated and an updraft is formed. Flame pillars are classified as continuous, intermittent, and buoyant flame zones. As the speed of the flame pillar of Mt. Halla (1950m) falls from the highest point it has risen, potential energy is converted into kinetic energy and is caused by the flow of fluid, solving these two equations equal, the volcanic eruption velocity is 87.5 m/s. At this time, the density of magma is inversely proportional to the temperature. Geomunoreum (456m) had an explosion speed of 42.6m/s.

• Clean Technology
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• v.27 no.1
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• pp.93-103
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• 2021

As the seriousness and necessity of responding to climate change and reducing carbon emissions increases, countries around the world are continuing their efforts to reduce greenhouse gases. Among various efforts, research on CCUS, capturing and utilizing carbon dioxide generated when using carbon-based fuels, is actively being conducted. Studies on pressurized oxy-fuel combustion (POFC) that can be used with CCUS are also being conducted by many researchers. The purpose of this study is to analyze basic information related to the flame structure and pollutant emissions of pressurized oxy-fuel combustion. For this, a counter-flow diffusion flame model was used to analyze the combustion characteristics according to pressure and oxygen concentration. As the pressure increased, the flame temperature increased and the flame thickness decreased due to a reaction rate improvement caused by the activation of the chemical reaction. As oxygen concentration increased, both the flame temperature and the flame thickness increased due to an improvement to the reaction rate and diffusion because of a change in oxidizer momentum. Analyzing the related heat release reaction by dividing it into three sections as the oxygen concentration increased showed that the chemical reaction from the oxidizer side was subdivided into two regions according to the mixture fraction. In addition, the emission index of NO classified according to the NO formation mechanism was analyzed. The formation trend of NO according to each analysis condition was presented.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.8
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• pp.743-752
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• 2013

This is the second paper on the combustion characteristics of landfill gas in a constant volume combustion chamber for a large displacement volume commercial engine, and it discusses the combustion process on the basis of pressure measurements. The results show that the bimodal peak pressure phenomenon, which is caused by the interaction of the heat release and the heat transfer, is more apparent as the mixtures are more favorable to combustion, and the magnitudes of the pressures depend on the unburned fraction. In addition, there exist four main inflection points during heat release owing to variations in the heat transfer area related to flame propagation from the ignition point. Furthermore, the number of inflection points increases as the mixture quality worsens because of the extended burn duration. Consequently, the sophisticated interactions between the heat transfer area changing pattern due to flame propagation and transfer duration might cause very peculiar heat release patterns.

• Journal of the Korea Furniture Society
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• v.21 no.6
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• pp.469-478
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• 2010

Fire resistance of new hybrid timber framed wall systems was evaluated in this study. These wall systems are composed of two major structural parts. One part is a heavy timber frame part designed to take charge of whole vertical load using heavy timber post and beam, and the other is an infill wall structure, designed to take charge of whole horizontal load and to provide an established level of fire resistance. A basic concept of this hybrid wall is adopted from a typical furniture structure with frame. A timber post and beam frame is constructed with Japanese Larch solid timber post(180mm by 180mm) and beam(180mm by 240mm). As infill wall systems, two types of walls are applied. One is a typical light timber framed wall with solid blocking and another is a structural insulated panel wall, in which polystyrene insulation is filled between two structural panels to make single structure. For all tested walls, two layers of 12.5mm thick type-X gypsum boards are used on fire exposed side. Prior to tests for hybrid walls, only infill walls are tested without heavy timber frame. All fire resistance tests are carried out in accordance with KS F 2257, and temperatures on several points within wall structure and unexposed wall surface are measured during fire tests. It is considered that the reinforcement of heavy timber frame is significantly efficient for improving the fire resistance of timber framed walls.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.160-168
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• 2003

In Korea, a large portion of aerial power-transmission cables is installed in the mountains. In the case of a fire in the mountains, steel wires coated with zinc and aluminum wires of those power cables exposed to the fire or near around will be deteriorated by the blaze and the high temperature. Deterioration proceeds by interactions of a variety of factors like quality, manufacturing process, the condition of installation and exposure environment of a wire, and so on. Generally, the characteristic of a conductor affect by a forest fire can not be analyzed without the effect through simulating a forest fire. However, there are little research accomplishments of that kind of simulation about it, and there's been no analysis of a sample exposed to an actual forest fire. This thesis shows the experimental results that apply to a new wire by an artificial flame-maker because it's difficult to directly analyze the characteristic of deterioration by a forest fire. Those results include the intensity of extension and wrench for a conductor. In addition, there's been an experiment and analysis about the mechanical characteristics of the wire of ACSR 480[$\textrm{mm}^2$] which was removed from Pohang area by a forest fire. Then, the database will be made to predict the state of deteriorated wires by a forest fire using those two data, and data necessary to diagnose the life state of an ACSR wire affected by a forest fire will be given.