• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.194-194
• /
• 2011

현대 사회에서 차량을 비롯한 선박, 항공기와 같은 각종 수송수단들은 그 용도와 형태도 다양하고 널리 보급되어있을 뿐만 아니라 각 분야에서 없어서는 안 될 필수품이 되어 있다. 그러나 수송수단의 수와 활용빈도수가 증가함에 따라 그로 인한 차량화재, 선박화재 그리고 항공기화재 등과 같은 특수화재의 발생에 따른 재산 및 인명피해의 문제점들도 함께 늘어나고 있는 실정이다. 2009년 기준, 1년 동안의 전체 화재발생건수 47,071건 가운데 차량화재의 발생건수가 5,958건으로서 전체의 12.6% 정도를 차지하였다. 그뿐만 아니라 차량 내장재의 주 재질은 가연성을 지닌 열가소성 합성수지들로서 화재가 발생하였을 경우, 다량의 가연성 가스 및 독성가스를 방출하기 때문에 인명 및 재산 피해를 증가시키는 문제점을 갖고 있다. 하지만 아직까지도 이와 같은 수송수단에 대한 화재를 예방하거나 피해를 최소화할 수 있는 화재진압대책 등에 관한 연구는 미흡한 실정이다. 따라서 본 연구에서는 이러한 문제점을 해결하고 과학적이며 체계적인 대응방안을 수립하기 위한 기초 자료를 확보하고 이를 통한 수송수단의 화재안전성을 분석하고자 각종 수송수단에서 사용되는 오일을 대상으로 연소특성 분석 및 화재하중에 관한 연구를 수행하였다. 분석 대상 오일은 연료용과 부속용 오일로 크게 분류되며, 연료용 오일로는 차량용 경유와 휘발유 그리고 군용차량용 경유, 항공기용 백등유와 제트유, 선박용 고유황경유 등을 선정하였다. 부속용 오일로는 브레이크오일, 파워오일, 엔진오일, 자동변속기오일, 수동변속기오일을 대상으로 각각 일반용과 고급형 2가지씩 시료를 선정하여 분석을 수행하였다. 분석방법은 대상오일들의 기초물성을 고찰하기 위해서 비중계를 이용하여 각 시료들의 비중을 측정하였으며, 문헌으로부터 끓는점, 어는점 및 점도 등을 조사하였다. 또한, 대상오일들의 착화특성을 살펴보고자 콘칼로리미터와 인화점 측정기 및 발화점 측정기 등을 이용하여 발열량, 착화시간, 발연량, 발화점, 인화점 등을 측정하였다. 대상오일들의 물성 및 착화특성에 대한 측정결과를 살펴보면, 비중은 $725.8{\sim}1072.0kg/m^3$ 정도의 값을 나타냈고, 인화점은 영하의 인화점을 갖는 휘발유의 경우, 장비의 특성상 분석이 곤란하여 측정하지 못하였으며, 다른 시료들은 $45.3{\sim}266.6^{\circ}C$정도의 값을 나타냈다. 발화점은 $325.7{\sim}600.6^{\circ}C$정도의 값을 갖는 것으로 나타났다. 따라서 이와 같은 결과들을 활용하면 차량, 선박, 항공기 등에 대한 화재발생과 관련된 화재안전성을 분석하고 이를 통한 수송시스템의 화재에 대한 예방 및 대응 방안의 효율성을 높일 수 있을 것으로 생각된다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.1
• /
• pp.25-33
• /
• 2018

Renewable energy has been of interests in the area of modern alternative fuels. Biogas is produced in waste landfill sites through anaerobic digestion processes, including hydrolysis, acidogenesis, organic acid fermentation (acetogenesis), and methane fermentation (methanogenesis). High contents of fine dust and moisture limited its utilization for direct combustion, town gas and vehicle fuel. Thus, this study proposed a new design for a cooling device using a centrifugal cyclone for simultaneous removal of fine dust and moisture as a pretreatment in the purification processes. A heat exchanger and an ID fan, which are installed inside and outside of the cyclone, in order to cool the humid gas below the freezing point and form a foggy mist. Such an atmosphere enhanced to capture fine dust as recirculating the cold mist flow. The water removal rate was 80.8% at a relative humidity of 95%, and the particle removal efficiency was 98.3% for $2.5{\mu}m$. Simultaneous removal efficiency was 70.8% and 99.6% for particle and moisture respectively.

• International Journal of Highway Engineering
• /
• v.7 no.4 s.26
• /
• pp.113-123
• /
• 2005

In this study, calcium chloride$(CaCl_2)$, sodium chloride (NaCl), organic acids-containing deicer(NS 40, NS 100), mixed deicier$(NaCl\;70%+CaCl_2\;30%,\;NS\;40\;70%+CaCl_2\;30%,\;NaCl\;70%+NS\;40\;30%,\;NS\;40\;70%+NaCl\;30%)$ is investigated based on the laboratory test for deicing performance, freez-thaw resistance of concrete, and corrosion rate of metal. Test items for deicing performance were ice melting and ice penetration, freezing point depressions and eutectic point, pH, thermal properties for selected deicing chemicals as well as their compatibility with concrete and metal were experimentally investigated. As a test results, in case of the use chloride-containing deicier in area that concrete structures has subjected to freez-thaw reaction in winter season, it showed that mixed deicing chemicals with optimum ratio has desirable method than use one deicing chemicals when is consider to deicing performance and effects, corrosion of steel materials, and freez-thaw resistance of concrete. When use various deicing chemicals mixed, NS40(70%)+calcium chloride(30%) showed the best effective method.

• Korean Journal of Food Science and Technology
• /
• v.35 no.1
• /
• pp.57-61
• /
• 2003

Variations in NMR relaxation time during freezing and thawing processes in pork loins were investigated. Continuous distribution analysis of data obtained from $T_2\;CPMG$ were carried out to observe the changes in water content in the muscles. Solid fat content slightly increased with decreasing temperature, then showed sharp increase at $-4^{\circ}C$, reaching 85% at $-25^{\circ}C$. Relaxation time decreased with decreasing temperature, suggesting that ice crystals gradually formed at freezing temperature. $T_2$ relaxation time during thawing was higher than that during freezing, suggesting that ice crystals melted by thawing and resulted in water loss from meat. Continuous distribution analysis of data obtained from Carr-Purcell-Meiboom-Gill experiments shows one to four components on the spectra during freezing and thawing processes. The area of major components between 30 to 45 ms decreased with decreasing temperature, and were not detected below $-4^{\circ}C$, below which only $T_s$ signal was detected. The area of $T_s$ decreased with decreasing temperature. Between -4 to $10^{\circ}C$, the areas of $T_m$ and $T_l$ during thawing were larger than those during freezing. These results suggest that the exchange between bound water and free water takes place during freezing and thawing.

• Journal of the Korean Electrochemical Society
• /
• v.3 no.4
• /
• pp.224-231
• /
• 2000

The exfoliation of graphite (layer) was progressed due to the irreversible insertion of PC molecules between graphene layers, when propylene carbonate (PC) solvent was used as the organic solvents. The problem could be mitigated by the replacement of PC by ethylene carbonate (EC). But, the freezing point of EC-based electrolyte increased due to the high freezing point of $EC(36.2^{\circ}C)$. Therefore, EC+PC mixed electrolyte is expected as a good organic electrolyte for lithium ion battery. The EC-based organic electrolyte containing PC within pertinent quantity can be expected to have high molar conductivity and reduced exfoliation of graphite layer. The dielectric constant and molar conductivity of $LiPF_6/PC+EC+DEC$ electrolyte was investigated with a variation in the PC content. The electrochemical properties of carbon electrode in the electrolyte were also investigated. Molar conductivity and dielectric constant increased linearly by increasing the PC volume fraction in the electrolyte. The results of charge-discharge test for carbon/electrolyte/Li cell indicated that the initial irreversible specific capacity(IIC) of MCMB-6-28s and MPCF3000 decreased by the addition of $0.83 vol\%$ of PC, but increased with PC content over than $0.83 vol\%$. In the case of MPCF3000 and PCG100 having less than $10 vol\%$ PC, IIC was lower than 50 mAh/g. The discharge specific capacities varied with carbon material, but did not vary with PC content in the electrolyte.

• Journal of the Korean Chemical Society
• /
• v.50 no.2
• /
• pp.141-152
• /
• 2006

In this study computer assisted instruction materials for the ‘Solution' chapter in high school chemistry II textbook were developed based on a view of particle and analyze the effect of the materials on 10th and 11th high school students. The contents of developed materials are dissolution, vapor pressure, the change of boiling point and freezing point, osmosis, and so on which are the major contents of Solution chapter in high school chemistry II textbook. Materials were developed with using animation and simulation for students understanding of the phenomena with a particle view point. Many phenomena in a solution were not simplified by colligative property of solution, but tried to explain by the concept of attraction between solute and solvent molecules. This computer assisted learning materials were developed using Flash 5.0 and Flash 6.0 Action Script. Educational effects of the materials on 10th and 11th grade students represented statistically meaningful increase of concept understanding. Especially the materials were effective to the transition stage or formal stage students in 10th grade and formal stage or the natural science major students in 11th grade.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.4
• /
• pp.1327-1337
• /
• 2018

Aviation fuel oil is more strictly controlled than other transport fuels because it can lead to major accidents in the event of a problem. The quality standards of the aircraft are specified by the domestic Korean Standard, the American Society for Testing and Materials and the International Air Transport Association, respectively. From 2016 to 2017, the quality analysis of 6 items such as aromatic content, sulfur content and distillation characteristics was carried out on the jet fuel produced at five domestic refineries. Domestic production of jet fuel has been shown to be in conformity with the quality standards and has been maintained at a constant level throughout the year. Compared with the specification of ASTM and IATA the aromatic content of domestic KS specification is set to be strictly 1.5 wt% higher than the ASTM and IATA setting specification, but it satisfies this specification sufficiently. In addition, other items such as sulfur content, distillation property and flash point satisfied both domestic and international specification.

• Korean Journal of Remote Sensing
• /
• v.33 no.2
• /
• pp.243-248
• /
• 2017

Sea ice which is an important component of the global climate system is being actively detected by satellite because it have been distributed to polar and high-latitude region. and the sea ice detection method using satellite uses reflectance and temperature data. the sea ice detection method of Moderate-Resolution Imaging Spectroradiometer (MODIS), which is a technique utilizing Ice Surface Temperature (IST) have been utilized by many studies. In this study, we propose a simple and effective method of sea ice detection using the dynamic threshold technique with no IST calculation process. In order to specify the dynamic threshold, pixels with freezing point of MODIS IST of 273.0 K or less were extracted. For the extracted pixels, we analyzed the relationship between MODIS IST, MODIS $11{\mu}m$ channel brightness temperature($T_{11{\mu}m}$) and Brightness Temperature Difference ($BTD:T_{11{\mu}m}-T_{12{\mu}m}$). As a result of the analysis, the relationship between the three values showed a linear characteristic and the threshold value was designated by using this. In the case ofsea ice detection, if $T_{11{\mu}m}$ is below the specified threshold value, it is detected as sea ice on clear sky. And in order to estimate the performance of the proposed sea ice detection method, the accuracy was analyzed using MODIS Sea ice extent and then validation accuracy was higher than 99% in Producer Accuracy (PA).

• Journal of the Korean Chemical Society
• /
• v.57 no.5
• /
• pp.640-655
• /
• 2013

The purpose of this study is to analyze the cognitive demands level of the description about 'changes of state' and 'kinetic theory' on the 'science 1' textbooks by the 2007 revised curriculum. The three types of curriculum analysis taxonomy have been used to analyze the cognitive demands level of those contents on the 6 kinds of 'science 1' textbooks. The most higher level of cognitive demands about the concepts have been discussed here due to the focus of the concepts. The first, the cognitive demand level about 'three states of substances' depending on the motion of their particles in 6 textbooks is a early formal operational stage because of using by the application of kinetic theory. The second, the cognitive demand level about 'diffusion' and 'evaporation' is a early formal operational stage, because the particles move around faster so they can change their position. The third, the cognitive level of the pressure and volume in a gas is a early formal operational stage because of explaining only phenomena in simple correspondence with formal model of kinetic theory. And simple functional relationships beyond linear on the graph of the volume and pressure of gas, the volume and temperature of gas is also a early formal operational stage. The fourth, the cognitive level of the energy of heat by a change of the state is also a early formal operational stage because kinetic theory picture accepted as providing explanation by the change of the state. And functional relationships beyond linear on the graph of the explanation of boiling point of water in water is also a early formal operational stage.