• 한국분무공학회지
• /
• 제6권4호
• /
• pp.22-30
• /
• 2001

The objective of this study is to develop the new equations for the calculation of higher heating values(HHVs) of reformed diesel fuels by ultrasonic treatment. Therefore, higher heating values of reformed diesel fuels by ultrasonic treatment are determined experimentally and calculated from their viscosity and surface tension measurements. The HHVs of the fuels are supposed to be a function of viscosity(Pa s) and surface tension(N/cm). The equations developed for the samples represent the correlation obtained by means of regression analysis. The HHVs calculated by developing new equations using viscosities showes the differences from the measured values ranging from -0.66 to 1.19 % and the correlation coefficient was -0.9411. The HHVs calculated by developing new equations using surface tensions showed the differences from the measured values ranging from -0.70 to 1.51 % and the correlation coefficient was 0.9999. The viscosity and the surface tension are characteristic properties of ultrasonic reformed diesel fuels for developing new formulae.

• 한국분무공학회지
• /
• 제17권3호
• /
• pp.121-127
• /
• 2012

The study is to investigate the mixing stability, fuel properties, and macroscopic spray characteristics of diesel-gasoline blended fuels in a common-rail injection system of a diesel engine. The test fuels were mixed diesel with gasoline fuel, which were based volume fraction of gasoline from 0 to 100% in 20% intervals. In order to analyze the blended effect of gasoline to diesel fuel, the properties of test fuels such as density, viscosity, and surface tension were measured. In addition, the spray behavior characteristics were studied by investigating the spray tip penetration and spray angle using a spray images through a spray visualization system. It was revealed that the density, kinematic viscosity and surface tension of diesel-gasoline blending fuels were decreased with the increase of gasoline fuel. The injection quantity of test fuels were almost similar level at short energizing duration condition. On the other hand, the increase of energizing duration shows the decrease of injection quantity compared to short energizing duration. The test blending fuels have similar growth in Spray tip penetration and Spray cone angle.

• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 2008년도 춘계학술논문발표회 논문집
• /
• pp.333-336
• /
• 2008

This study is the result between the variation of fuel moisture and the risk of forest fire through measuring the change of moisture containing ratio on-site and its average analysis for each diameter of surface dead fuels in the forest. The measurement was performed on six days from the day after a rainfall. The fuel moisture on-site was measured on the day when the accumulated rainfall was above 5.0mm, and the measurements was 2 times in spring. From the pine forest which were distributed around Samcheok and Donghae in Kangwondo, three regions were selected by loose, medium, and dense forest density, and the fuel moisture was measured on the ranges which are less than 0.6cm, 0.6-3.0cm, 3.0-6.0cm, and more than 6.0cm in the forest for six days from the day after a rainfall. The study showed that the moisture containing ratio converged on 3 - 4 days for surface deads fuels which diameter are less than 3.0cm and the convergence was made more than six days for ones which diameters are more than 3.0cm except the surface dead fuel of 3.0-6.0cm diameter of loose forest density.

• Journal of Radiation Protection and Research
• /
• 제36권4호
• /
• pp.174-182
• /
• 2011

With the reactor operation conditions - 4.3 wt% $^{235}U$ initial enrichment, burn-up 55,000 MWd/MTU, average power 34 MW/MTU for three periods burned time for 539.2 days per period and cooling time for 100 hours after shut down, to set up the condition to determine the minimum height (depth) of spent fuel storage pool to shut off the radiation out of the spent fuel storage pool and to store spent fuels safely, the dose rate on the specific position directed to the surface of spent fuel storage pool induced by the neutron and gamma-ray from spent fuels are evaluated. The length of spent fuel is 381 cm, and as the result of evaluation on each position from the top of spent fuel to the surface of spent fuel storage pool, it is difficult for neutrons from spent fuels to pass through the water layer of maximum 219 cm (600 cm from the floor of spent fuel storage pool) and 419 cm (800 cm from the floor of spent fuel storage pool) for gamma-ray. Therefore, neutron and gamma-ray from spent fuels can pass through below 419 cm (800 cm from the floor) water layer directed to the surface of spent fuel storage pool.

• 한국화재소방학회논문지
• /
• 제22권3호
• /
• pp.258-264
• /
• 2008

본 논문에서는 산불의 한 형태인 지표화의 체계적인 연구를 위해 열량분석과 연소특성에 관한 실험방법과 측정 시스템을 제안하여 향후 산불 관련 연구에 있어서 이를 활용하고자 한다. 또한 제안된 방법과 시스템의 효용성을 나타내고자 부분적인 결과를 논문에 제시 하였다. 이를 위하여 지표화의 대표적인 연소 물질인 침엽수종과 활엽수종 낙엽을 선정하여 밀도 및 시료의 용기 크기를 변화시켜 가며 실험하였다. 열량분석은 통상 사용되는 분석기기 중 열중량 분석기(TGA : Thermogravimetric Analyzer), 연소열 측정장치(Oxygen Bomb Calorimeter)를 이용하여 분석하였으며, 연소특성은 기존의 이론적 모델로 가장 잘 알려져 있는 Pool fire모델에 따른 모의 연소실험을 통하여 지표화 상부의 열 유체속도, 연소온도, 화염 높이에 따른 열방출 속도, 연소 질량감소 속도 둥을 측정하여 분석하였다. 언급된 변수들은 지표화의 위험성 및 산불확산 예측에 기초 자료로 사용할 수 있다.

• 한국수소및신에너지학회논문집
• /
• 제23권5호
• /
• pp.513-520
• /
• 2012

The electrochemical reaction of refuse derived fuel (RDF) and refuse plastic/paper fuel (RPF) was investigated in the direct carbon fuel cell (DCFC) system. The open circuit voltage (OCV) of RPF was higher than RDF and other coals because of its thermal reactive characteristic under carbon dioxide. The thermal reactivity of fuels was investigated by thermogravimetric analysis method. and the reaction rate of RPF was higher than other fuels. The behavior of all sample's potential was analogous in the beginning region of electrochemical reactions due to similar functional groups on the surface of fuels analyzed by X-ray Photoelectron Spectroscopy experiments. The potential level of RDF and RPF decreased rapidly comparing to coals in the next of the electrochemical reaction because the surface area and pore volume investigated by nitrogen gas adsorption tests were smaller than coals. This characteristic signifies the contact surface between electrolyte and fuel is restricted. The potential of fuels was maintained to the high current density region over 40 $mA/cm^2$ by total carbon component. The maximum power density of RDF and RPF reached up to 45~70% comparing to coal. The obvious improvement of maximum power density by increasing operating temperature was observed in both refuse fuels.

• 한국분무공학회지
• /
• 제6권3호
• /
• pp.38-44
• /
• 2001

The effect of four diesel fuels with oxygenated agents fuels on spray properties from plain-orifice atomizer was investigated. The oxygenates evaluated were diglyme, MTBE, DEE and DMM and were blended in weights of 5, 10, 15, 20 and 30% in a baseline diesel fuel. The physical properties such as surface tension, density and viscosity are also measured for each blended oxygenated fuels. It was found that changes in physical properties of fuels considered are enough to influence spray properties, i.e. spray angle, spray tip penetration and mean drop size. Spray properties were measured by PMAS(particle motion analysis system) which is employing a point measurement technology. Spray angle increased with increase in oxygenate content. The effect, however, was not great in the higher blend level. The oxygenated fuels produced more shorter spray tip penetration than diesel fuels. SMD was decreased with the increase in blending percent. SMD for DMM and DEE are represented 10.33 and 3.41% decreasing rates respectively. It was found that changes in spray characteristics of oxygenated fuel were easily large enough to impact pollutant emissions. It was clear from this study that spray characteristics of oxygenated fuel is one of possible cause of reducing pollutant emissions. It was clear from this study that spray characteristics of oxygenated fuel is one of possible cause of reducing pollutant emissions from diesel engines when oxygenated fuels is applied.

• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 2010년도 추계학술발표회 자료집
• /
• pp.380-384
• /
• 2010

본 연구는 가을철 산불조심기간 중 영동지방 활엽수림에 대하여 임분별로 강우 후 익일부터 6일간 임내의 지표연료를 직경별 0.6cm 이하, 0.6~3.0cm, 3.0~6.0cm, 6.0cm 이상에 대한 연료습도 변화를 실측하는 한편, 기상인자를 고려한 통계분석을 실시하여 경과일수별 연료습도추정 예측식을 개발하였다. 결정계수인 $R^2$ 값은 0.75~0.90의 적합성을 나타내었으며, 향후 강우 후 기상자료를 이용하여 임내 연료습도를 예측하여 산불위험예보로 활용하는데 매우 유용한 자료로 이용할 수 있을 것으로 판단된다.

• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
• /
• pp.434-437
• /
• 2008

In this study, we developed a fuel moisture variation prediction model on each day after precipitation during a spring forest fire exhibition period. For this research, we selected plots in pine forest on Sam-Chuck si and Dong-hae si in Kangwon do according to a forest density(low, mediate, high) and classified a surface woody fuel by a diameter.(below 0.6cm, $0.6{\sim}3cm$, $3{\sim}6cm$, and above 6cm). A validity of this model was verified by applying a fuel moisture variation after precipitation in this spring. In the result, $R^2$ was $0.76{\sim}0.92$. This model will be a useful for improvement of a forest fire danger rate forcast through a prediction a fule moisture in forest.

• 대한기계학회논문집B
• /
• 제40권11호
• /
• pp.697-704
• /
• 2016

본 논문에서는 역청탄인 Glencore 탄을 염산과 질산수용액을 이용하여 산 처리하고 원탄과 산 처리 된 석탄의 물리, 화학적 비교분석과 직접탄소 이용 연료전지(Direct Carbon Fuel Cell, DCFC)의 성능 비교 분석을 수행하였다. 석탄의 물성들을 분석하기 위해 열중량 분석과 가스 흡착법, X선 광전자 분광법을 수행하였다. 열중량 분석을 통해 연료의 열적 반응성이 증가하였음을 알 수 있었고, 가스 흡착법 결과로 기공의 평균지름은 변화가 없었지만 표면적은 감소함을 알 수 있었다. X선 광전자 분광법에서는 $HNO_3$ 처리의 경우 가장 높은 산소/탄소 비율을 보였고, 이를 통해 다양한 표면 산소작용기가 증가한 것을 확인하였다. 연료의 표면 물성과 전기화학 성능을 비교한 결과, 표면의 산소 성분의 변화가 DCFC의 성능 향상에 가장 큰 영향을 미침을 알 수 있었다.