• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.362-368
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• 2016

In the recent International Maritime Organization's (IMOs) Maritime Safety Committee's 93rd session, the International Chamber of Shipping and International Parcel Tankers Association addressed marine fuel oil quality problems: increasing diluents in marine fuel oil, ignition in engine rooms due to the low flash point of fuel oil, and marine fuel oils that can damage marine engines. To deal with these marine fuel oil quality problems, the International Maritime Organization secretariat appointed the worlds marine fuel oil monitoring institute and constituted a correspondence group to determine the fuel oil quality required by MARPOL Annex VI regulation 14.8 (sulfur content less than 0.5%). In this study, basic research that can help with responding to marine fuel quality issues and the IMO's work is conducted. In order to perform this basic research, the off-spec ratio related to the fuel oil quality standard (ISO 8217:2012), density distribution tendency, gross specific energy, and correlation between components in the fuel oil are analyzed through actual marine fuel oil (residual marine fuel) data from the Port of Singapore.

• Journal of Acupuncture Research
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• v.19 no.2
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• pp.114-127
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• 2002

Objective : The purpose of this study is to investigate the mechanism and effect of moxibustion objectively and to be used as the quantitative data for developing the new thermal stimulating treatment by observing the combustion time and temperature of commercial moxaes. Methods : We have selected two types(large-size moxa A(LMA), large-size moxa B (LMB)) among large moxaes used widely in the clinic. We examined combustion times, temperatures in each period during a combustion of moxa. Results : 1. The combustion time in the preheating period was about 30sec in both moxaes on the non-contact heated surface. 2. The combustion time in the heating period was about 345sec in LMA and about 1391 sec in LMB, about 4 times longer in LMB on the non-contact surface. 3. The maximum temperature in the heating period was $44.5^{\circ}C$ in LMA and $45.4^{\circ}C$ in LMB respectively, higher by $0.9^{\circ}C$ in LMB. The average temperature in the heating period was $35.5{\sim}37.6^{\circ}C$ in LMA and $36.0{\sim}39.8^{\circ}C$ in LMB, a little higher in LMB. 4. The combustion time in the retaining period in LMA was 45.4sec and 13% of that in the heating period, and in LMB 594.7sec and 43% of that in the heating period on the non-contact surface. 5. On the point(PH) measured maximum temperature, the average temperature during the retaining period was $44.0^{\circ}C$, $42.9^{\circ}C$ respectively and the temperature at an end of the retaining period was $43.0^{\circ}C$, $40.2^{\circ}C$ respectively. 6. The time at a beginning of the cooling period was about 418 sec from ignition in LMA and 2021sec in LMB, and the temperature at that time was $36.9{\sim}39.1^{\circ}C$ on the non-contact surface. Conclusion : It was thought that not only the figure of moxicombustion device, but also the form and size of moxa had influence on the combustion characteristics deciding the performance of stimulus seriously.

• Fire Science and Engineering
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• v.30 no.3
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• pp.104-109
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• 2016

Candle fires do not occur frequently, but can easily result in death. In this study, the thermal characteristics of candles and conditions and debris of candle fires were investigated to determine the causes of candle fires. The rates of decrease in weight of 10 candles were measured and found to be between 2.6 g/h and 6.7 g/h. Most candle fires are caused by the ignitiong of combustible materials close to them. The temperature near a candle ranges from about $200^{\circ}C$ to $400^{\circ}C$ at a distance of 1 cm and low ignition temperature materials such as papers can easily catch fire. The melting temperature of candles ranges between $50^{\circ}C$ and $70^{\circ}C$ and their major chemical components are fatty acids and normal hydrocarbons (over C20). Using pretreatment conditions involving the use of activated charcoal strips at $150^{\circ}C$ for 16 hours, the fire debris including candle residues were analyzed using a Gas-chromatograph/Mass-spectrometer (GC/MS).

• Fire Science and Engineering
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• v.29 no.2
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• pp.79-83
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• 2015

The fire accident is a representative type of disaster that can largely impact on business. Therefore, precautionary measures and rapid initial response is very important when a disaster occurs. The storage of porous combustibles is inevitable in coal yard, plywood processing industry, and others that are currently operating. Initial fire fighting of fire and identifying the ignition point in such a porous combustible storage space are so difficult that if the initial response is failed, being led to deep-seated fire, surface fire is likely to result in secondary damage. In addition, deep-seated fire can cause personal injuries and property damage due to a large amount of toxic gases and reignition. Therefore damage reduction measures is required around the storage space to handle a porous flammable. Improving the penetration performance of the concentration of the surfactant is carried out as underlying study, which is about an deep-seated fire extinguishing efficiency augmentation when using wetting agents. The porous materials used in the experiments is radiata pine wood flour, which occupies more than 75% of the domestic wood market. Fire fighting water is selected as Butyl Di Glycol (BDG), which is being used for infiltration extinguishing agent, and the experiment was carried out by producing a standard solution. The experiment was carried out on the basis of the Deep-Seated Fire Test of NFPA 18. The amount of watering, porous material to the internal amount of penetration, and runoff measurement out of the porous material was conducted. According to experimental results, as the surface tension is reduced, the surfactant concentration macroscopic penetration rate decreases, but infiltration to a porous material is shown to have growth characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.259-267
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• 2010

In this study, the effect of particle size on the combustion characteristics of pulverized sub-bituminous coal was experimentally investigated. A laminar-flow-entrained reactor was designed and implemented to realize the desired heating ratio and temperature corresponding to the combustion atmosphere of a pulverized-coal-fueled furnace. The flame length and structure of burning particles according to different sizes were investigated. Coal combustion processes were clearly distinguished by direct visual observation of the flame structure. The onset point of volatile ignition is greatly affected by changes in the particle size, and the burning time of the volatiles is least affected by changes in the particle size. The length and instability of char flame also increase with the increase of the particle size. However, the char consumption rate within the residential time remains nearly constant.

• Fire Science and Engineering
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• v.26 no.4
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• pp.48-54
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• 2012

In order to study on the evacuation risk when connate fires caused by vertical fire spread of the exterior occurs, the egress simulations based on the relevant scenarios has carried out. As a result of it, ASET (permitted evacuation time) was reached in between 550 to 650 seconds in entire floors after vertical smoke spread from fire of combustible exteriors. In particular, ASET was 358 seconds in the first floor, 490 seconds in the six floor and 473 seconds in the tenth floor. In addition, five floors of all levels, the 1st floor, the 6th floor and the 28th floor ~30th floor, show RSET (minimum evacuation time) which is bigger than ASET as evacuation risk. This result presents occupants in high rise buildings with more than 15 floors might not be able to egress of them using staircases due to huge population attempting to evacuate simultaneously. Particularly, 699 people in the upper levels by smoke from the first floor are having difficulty escaping this building since ASET on the first floor adjacent to the ignition point was 358 seconds which is relatively reached fast. Considering a prevention method of the fire and smoke spread, architects have to use non-combustible exterior in the building's facade to be required as an active fire protection system.

• Fire Science and Engineering
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• v.31 no.5
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• pp.37-43
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• 2017

Domestic sandwich panel buildings are widely used on walls and roofs of factories and warehouse facilities. Factory and warehouse facilities have high fire load and rapid spread of fire due to their use characteristics, leading to large fires. Due to the characteristics of materials, walls and roofs are collapsed, resulting in life damage and property damage. In this regard, this study examined domestic and international standards of sprinkler facilities to prevent ignition of sandwich panel walls. Also, in order to check whether the fire was prevented by installing the head on the wall of the sandwich panel, the fire test was carried out with 10 cm, 60 cm, and 120 cm from the wall along the sprinkler head installation standard of domestic fire safety standards. As a result of the fire test, it was confirmed that the sandwich panel was prevented from igniting when the head of water pressure 0.1 MPa and water quantity K-80 was installed. According to the separation distance, it was impossible to measure the temperature at 10 cm, but at 60 cm, At the maximum temperature of $525^{\circ}C$ and 120 cm, the maximum temperature of the wall of the sandwich panel was measured as $276^{\circ}C$. As a result of the fire test, considering the fire point of 450 degrees Celsius in the fire test of the sandwich panel, the distance from the sandwich panel wall to the combustible is more than 120 cm.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.610-619
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• 2022

Hydrogen is emerging as an alternative fuel for eco-friendly ships because it reacts with oxygen to produce electrical energy and only water as a by-product. However, unlike regular fossil fuels, hydrogen has a material with a high risk of explosion due to its low ignition point and high flammability range. In order to safely use hydrogen in ships, it is an essential task to study the flow characteristics of hydrogen leakage and diffusion need to be studied. In this study, a numerical analysis was performed on the effect of leakage, ventilation, etc. on ventilation performance when hydrogen leaks in an enclosed space such as inside a ship. ANSYS CFX ver 18.1, a commercial CFD software, was used for numerical analysis. The leakage rate was changed to 1 q, 2 q, and 3 q at 1 q = 1 g/s, the ventilation rate was changed to 1 Q, 2 Q and 3 Q at 1 Q = 0.91 m/s, and the ventilation method was changed to type I, type II, type III to analyze the ventilation performance was analyzed. As the amount of leakage increased from 1 q to 3 q, the HMF in the storage room was about 2.4 to 3.0 times higher. Furthermore, the amount of ventilation to reduce the risk of explosion should be at least 2 Q, and it was established that type III was the most suitable method for the formation of negative pressure inside the hydrogen tank storage room.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.9-13
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• 2022

Bullets flying with a light from the back are called "tracers". Tracers are ignited by the combustion gas of the propellant and emit bright light that allows the shooter to visually trace the flight path. Therefore, tracers mark the firing point for allies to assist shooters to hit target quickly and accurately. Conventional tracers are constructed with a mixture of an oxidizing agent, raw metal, and organic fuel. Upon ignition, the inside of the gun can be easily contaminated by the by-products, which can lead to firearm failure during long-term shooting. Moreover, there is a fire risk such as forest fires due to residual flames at impact site. Therefore, it is necessary to develop non-combustion type luminous material; however, this material must still use the heat generated from the propellant, so-called "thermoluminescence (TL)". This study aims to compare the TL emission of Dy³⁺, La³⁺ and Ho³⁺ doped MgB₄O₇ phosphors prepared by solid state reaction. The crystal structures of samples were determined by X-ray diffraction and matched with the standard pattern of MgB₄O₇. Luminescence of various doses (200 ~ 15,000 Gy) of gamma irradiated Dy³⁺, La³⁺ and Ho³⁺ (at different concentrations of 5, 10, 15 and 20 %) doped MgB₄O₇ were recorded using a luminance/color meter. The intensity of TL yellowish (CIE x = 0.401 ~ 0.486, y = 0.410 ~ 0.488) emission became stronger as the temperature increased and the total gamma-ray dose increased.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.8
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• pp.554-563
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• 2013

The purpose of this study is to evaluate the possibility of nutrient release at up and downstream of Kangchun weir, upstream of Yuju and Ipo weir in Namhan River. For this survey, we measured basic characteristics of the sediments (water content, ignition loss, TOC, TP, SRP, TN, phosphorus fractionation) and conducted nutrients release experiments under both aerobic and anaerobic condition. The overlying water from the sediment-water column was analyzed for nutrients (i.e. TP, $PO_4$-P, TN, $NO_3$-N, $NH_3$-N) everyday for 18days. Result of soil texture experiment showed that sediments are Sand. SRP concentration before the release experiment was different with the value after the release experiment. According to this result, we can find that there were more activated release processes in anaerobic condition. $PO_4$-P increased from 1 to 8 days and remained at the maximum value (7~8 days) afterward. The rapidly increase of $PO_4$-P was observed from 1 to 2~3 days whereas the TP continuously increase from 1 to 18 days. The $PO_4$-P release rate calculated by up to 7~8 days data highly correlated with initial SRP concentration with $R^2$=0.8502. $NO_3$-N release rate appears constantly decreasing trend as -5.7~-3.08 $mg/m^2{\cdot}day$, otherwise the $NH_3$-N release rate, by-product of a organic matter decomposition using nitrate as electron acceptor, was 0.57~2.41 $mg/m^2{\cdot}day$. Substantial portion in TN can be induced by organic nitrogen which originated from the tributary passing through non-point pollutant source. Compared with other similar researches, phosphorus and nitrogen release rates obtained in this study can be considered as relatively low values. Since this study targeted the sediments accumulated by one time of flooding season, there are limitation to generalize theses results. Therefore, it is necessary to consistently monitor and investigate the accumulation of nutrients in the sediment for understanding the effect of weir construction on the overlying water quality.