• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.3
• /
• pp.309-314
• /
• 2012

Flame flickering occurs mainly because of the buoyancy force for pool fires under ambient air. The cup-burner flame was used for experimental investigation of the effect of the oxidizer velocity on the gravitational instability. The results showed that the flickering frequency decreased with increasing oxidizer velocity. The frequency-buoyancy relation with nondimensional variables coincided with that of the buoyant flume and pool fires when the characteristic velocity was defined as the difference between the fuel and oxidizer velocities, which implies that the origin of the gravitational instability is the Kelvin-Helmholtz instability in the shear layer. The effect of the oxidizer composition on the instability was also examined through nitrogen dilution in the oxidizer stream. As the concentration of inert gas increased, the length of the blue flame increased and lift-off behavior was observed. The oscillation frequency was independent of the dilution ratio, but was related to the local flame structure.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2008.11a
• /
• pp.456-460
• /
• 2008

This study was on basic step to develop a good clean extinguishing agent. In order to get a satisfactory result, we tested fire extinguishing ability using Novec which is inert gas. In study used to Cup Burner Test its made by international standard ISO-14520 regulations of gaseous extinguishing agent ability test. The finding is that a new clean agent, Novec has a very efficient extinguishing ability in a state of gas.

• Journal of the Korean Society of Safety
• /
• v.23 no.6
• /
• pp.95-99
• /
• 2008

Halon was known as a cause of the ozone layer destruction. In 1987, it was designated as one of the ozone-layer-destroying materials in the Montreal Protocol. Therefore substitutes of Halon agent has been developed including inert gas extinguish system, which is one of the most widely used fire extinguishing system. This study intended to increase the efficiency of inert gas extinguishing agent by using inert gas additives. As IG-541 shows high extinguishing power, the experiment was performed to measure the effects of gaseous additives to it. Cup-burner fire extinguishing apparatus was used with n-Heptane fuel. Among many of pure inert gaseous agents, Helium showed the most excellent extinguishing power. When Helium was added to IG-541, fire extinguishing power was increased and the concentration of oxygen in chimney also risen. By adding Helium to IG-541, the effectiveness of inert gas fire extinguishing system is able to be increased.

• Fire Science and Engineering
• /
• v.8 no.1
• /
• pp.3-8
• /
• 1994

A new test system was established to measure the flame extinguishing concentration of Halon alternatives. The main characteristic of this system is to use the solid paraffin with a wick instead of liquid fuel, such as n-Heptane. Our results showed that the extinguishing concentration of compounds was lower than that of other existing data, but the trend was consistent with others. The flame extinguishing concentration of all tested compounds were not almost effected by gas flow velocity. The system produces good reliable data with a minimum error for measuring the flame extinguishing concentration. Therefore our new system can be utilized as a standard equipment to evaluate Halon alternatives.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2009.04a
• /
• pp.483-486
• /
• 2009

국제사회의 할론계 소화약제 사용규제가 본격화 되면서 차세대 소화약제에 대한 개발은 시급한 사안으로 다가왔다. 그중에서도 청정소화약제에 해당하는 가스계 소화약제의 개발은 상당히 진척되었으며, 가스계 소화약제의 소화성능에 관한 평가는 화재발생시 인명과 재산상의 손실을 최소화하기 위한 중요한 평가요소이다. 본 연구는 기존의 이산화탄소 소화약제와 새로운 형태의 소화약제인 Novec의 소화성능을 비교 평가하기 위해서 Cup Burner Test를 이용하여 실험을 행하였으며, 에탄올, 노르말헵탄, 톨루엔과 가솔린을 원료하여 실험한 결과 Nocvec의 소화성능이 이산화탄소 소화약제보다 우수한 것으로 나타났다.

• Korean Journal of Heritage: History & Science
• /
• v.56 no.2
• /
• pp.62-78
• /
• 2023

The act of burning incense originated from Buddhist rituals and customs, and gradually formed its own culture. In the Goryeo Dynasty, in addition to religious and national rituals, incense came to be enjoyed more generally and widely. In particular, Goryeo literati enjoyed the elegant lifestyle of staying home and burning incense. This was part of a regional culture shared across East Asia. Such incense burning applied the same methods as were used during the same period in China. In collections of writings from the Goryeo Dynasty, it can be seen that incense methods such as gyeok-hwa-hoon-hyang (隔火熏香) and jeon-hyang (篆香) were used. A particular method of incense influenced the size and shape of the incense burner utilized. Small incense burners suitable for simple everyday incense were used, such as the hyangwan (香垸), a cup (wine glass)-shaped burner. White porcelain incense burners from Song were discovered in Gaegyeong, and celadon incense burners from Goryeo were made in the same shape. This phenomenon shows that there was great demand for ceramic incense burners in Goryeo in the 12th and 13th centuries. During this period, incense burners that imitated metalware were produced, and some applied the techniques and patterns of Goryeo celadon. The Goryeo Dynasty-era incense burner was basically a necessity for use in various rituals, but gradually came to be widely used also by individuals.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.12
• /
• pp.1193-1199
• /
• 2012

A cup burner experiment was performed to investigate the effect of the oxidizer velocity and concentration on flame instability near extinction. Heptane was used as a fuel and air diluted by nitrogen and carbon dioxide was used in the oxidizer stream. Two types of flame instabilities at the flame base and at axial downstream were observed near extinction. The instability at the flame base could be characterized by cell, swing, and rotation modes, and the cell mode changed to the rotation mode through the swing mode as the oxidizer velocity increased. To assess the parameters for the flame instability, the initial mixture strengths, Lewis number, and adiabatic flame temperature were investigated under each condition. The Lewis number might be the most important among them, but it is impossible to generalize because of the insufficient number of cases. Furthermore, the axial periodic flickering motion disappeared at low and high oxidizer velocities near extinction. This resulted from the fact that low oxidizer velocity induced evaporated fuel velocity below the critical velocity and high velocity made the reacting fuel velocity comparable.

• Journal of the Korean Society of Safety
• /
• v.27 no.1
• /
• pp.20-25
• /
• 2012

The purpose of the study is to assess the extinguishing concentration of inert gases in engine nacelle fire. The experiment was performed with a two dimensional rectangular bluff body stabilized flames, where the fuel was ejected to counter flow and co-flow against an oxidizer stream. Two inert gases, $CO_2$ and $N_2$, were used for extinguishing agent in the oxidizer and methane was used for fuel. The main experimental parameters were the direction of injecting fuel, the kinds of agent and the velocity ratio between air and fuel streams, which controlled the mixing characteristic near bluff body and the strength of recirculation zone in the downstream. The result shows the flame structure and the mode were strongly dependent with fuel/air ratio and the fuel jet direction. For both flow configurations, the extinguishing concentration of $CO_2$ was smaller than the $N_2$ because of the large heat capacity of $CO_2$. However, the concentration of inert gasesat blowout was much smaller than those in the cup burner and coflow jet diffusion flames, which implies that the extinction mechanism of bluff body stabilized flames was mainly due to the aerodynamic aspect. Compared to co-flow fuel injection, the extinguishing concentration of inert gases under counter flow configuration was lower. The effect of direction might result from the mixing characteristic and strength of recirculation zonearound a bluff body. More details should be investigated for the characteristic of recirculation zone in the wake of bluff body using the LES(Large Eddy Simulation).

• Journal of the Korean Society of Safety
• /
• v.34 no.1
• /
• pp.27-33
• /
• 2019

Combustion characteristics of gasoline/ethanol fuel were investigated both numerically and experimentally for vehicle fire safety. The numerical simulation was performed on the well-stirred reactor (WSR) to simulate the homogeneous gasoline engine and to clarify the effect of ethanol addition in the gasoline fuel. The simulating cases with three independent variables, i.e. ethanol mole fraction, equivalence ratio and residence time, were designed to predict and optimized systematically based on the response surface method (RSM). The results of stoichiometric gasoline surrogate show that the auto-ignition temperature increases but NOx yields decrease with increasing ethanol mole fraction. This implies that the bioethanol added gasoline is an eco-friendly fuel on engine running condition. However, unburned hydrocarbon is increased dramatically with increasing ethanol content, which results from the incomplete combustion and hence need to adjust combustion itself rather than an after-treatment system. For more tangible understanding of gasoline/ethanol fuel on pollutant emissions, experimental measurements of combustion products were performed in gasoline/ethanol pool fires in the cup burner. The results show that soot yield by gravimetric sampling was decreased dramatically as ethanol was added, but NOx emission was almost comparable regardless of ethanol mole fraction. For soot morphology by TEM sampling, the incipient soot such as a liquid like PAHs was observed clearly on the soot of higher ethanol containing gasoline, and the soot might be matured under the undiluted gasoline fuel.