• 동력기계공학회지
• /
• 제11권1호
• /
• pp.51-55
• /
• 2007

A study on combustion characteristics using emulsified fuel in a diesel engine were performed experimentally. In this paper, the experiments were performed at engine speed 1800rpm, emulsion ratios were 0%, 10%, 20%, and main measured items were specific fuel consumption, cylinder pressure, rate of pressure rise, rate of heat release etc. The obtained conclusions were as follows. 1) Specific fuel consumption increased maximum by 19.8% at low load, but was not affected at full load. 2) Rate of pressure rise and rate of heat release were about the same in the case of 10% and 20% of emulsion ratio. 3) Cylinder Pressure increased 9.6%, rate of pressure rise increased 53.4% in case of emulsion ratio 20% at full load. 4) Rate of heat release increased 72.4% in case of emulsion ratio 20% at full load.

• 대한기계학회논문집B
• /
• 제33권4호
• /
• pp.248-254
• /
• 2009

The HCCI engine is a next generation engine, with high efficiency and low emissions. The engine may be an alternative to SI and DI engines; however, a pressure rise rate is a major limitation for high load range and power reduction. Recently, we were able to reduce the pressure rise rate using thermal stratification. Nevertheless, this was insufficient to produce high power. In this study, the reduction of the pressure rise rate using thermal stratification was confirmed and the HCCI engine power was increased using the boost pressure. The rate and engine power were produced by CHEMKIN and modified SENKIN. As a result of increasing the boost pressure, a higher IMEP was attained while the pressure rise rate increased only slightly in the HCCI with thermal stratification.

• 한국안전학회지
• /
• 제32권2호
• /
• pp.46-51
• /
• 2017

This paper presents classification of domestic fire detector using response time index. Response time is measured using fire detector distributed in Korea, and the response time index is estimated. Plunge test prescribed by FM is conducted to measure response time of fire detector. The detector used to test is fixed temperature type(thermistor and bimetal type) and rate of rise temperature type(thermistor and pneumatic type). The nominal operation temperature of fixed temperature type detector is $70^{\circ}C$ and rate of rise temperature is $15^{\circ}C/min$. The fixed temperature type is measured 7 products, and the rate of rise temperature type is measured 5 products. The results show that in case of fixed temperature type(thermistor) is classified "Quick" or "Standard" and fixed temperature type(bimetal) is not classified. The rate of rise temperature type(thermistor) is classified "Fast" or "Ultra Fast" and the rate of rise temperature type(pneumatic) is classified "Very Fast" or "Ultra Fast". The pneumatic type shows more fast response than thermistor type. Also these results indicate the fixed temperature type(bimetal) is not suitable for early stage fire detection.

• 한국안전학회지
• /
• 제9권1호
• /
• pp.61-67
• /
• 1994

Rate of rise heat detectors that respond to the heat generated in fire plume and alarm when the temperature reaches a specified point, give a great influences to the loss of life and property according to their reaction sensitivity. In this study, simple equations were derived which can be predicted the response time and temperature of the rate of rise heat detector with the results of hot wind tunnel tests and compartment fire experiments.

• International Journal of Internet, Broadcasting and Communication
• /
• 제12권1호
• /
• pp.95-103
• /
• 2020

In the study, we show the six metropolitan cities, Incheon Metropolitan City had the highest annual average rate(3.2%) of the death toll, from 2011 to 2018, and the overall annual average rise rate was 2.6%. Also, the annual average rise rate of the number of cremators using E-Haneul funeral information system, Gwangju Metropolitan City had the highest rate(7.6%) and the overall annual average rise rate was 5.6%. The annual average rise rate of the cremation rate, Gwangju Metropolitan City had the highest rate(2.8%) and the overall annual average rise rate was 1.9%. Focusing on the actual state shown in the results of this study above, the policy measures for improving the efficiency of supply & demand policy of funeral facilities in six metropolitan cities in the whole nation could be suggested as follows. First, expanding the supply of cremation facilitiesin consideration of the installation period of cremation facilities. Second, given the increase in the number of cremators using E-Haneul Funeral Information System, it is necessary to expand the infrastructure for meeting the demand of using funeral facilities, such as enshrinement facilities of ash and natural burial sites. Third, in such metropolitan cities, it is difficult to resolve a conflict of location with local residents who recognize cremation facilities as unpleasant facilities. Therefore, it is necessary to devise and implement a plan for improving local residents awareness of cremation facilities and resolving the conflict of location in diversified ways. Fourth, it is predicated that Busan and Daegu Metropolitan City will face a lack of supply of cremation facilities in a short time due to the increased demand for them. Therefore, in order to meet the demand for cremation, it is necessary to construct more cremation furnaces in current cremation facilities or to jointly use and expand cremation facilities with their neighboring local government.

• 한국자동차공학회논문집
• /
• 제18권3호
• /
• pp.19-25
• /
• 2010

The purpose of this study is to gain a better understanding of the effects of fuel stratification on reducing the pressure-rise rate at high load in HCCI combustion. It was found that fuel stratification offers good potential to achieve a staged combustion event and reduced pressure-rise rates. The engine is fueled with Di-Methyl Ether (DME) which has unique 2-stage heat release. Numerical analysis is conducted with single and multi-zones model and detailed chemical reaction scheme is done by chemkin and senkin. Calculation result shows that proper fuel stratification prolongs combustion duration and reduce pressure rise rate. Besides IMEP, combustion efficiency and indicated thermal efficiency keep constant. However, too wide fuel stratification increases pressure rise rate and CO and NOx emissions in exhaust gas.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
• /
• pp.6-10
• /
• 2003

Accurate description of starting transient history allows and justifies the use of small margin of safety for the engine parts, resulting in high motor mass ratio in addition to satisfying the control and guidance requirements of the vehicle. Studies have been carried out for the prediction and reduction of ignition peak and pressure-rise rate during the starting transient of solid rocket motors. Numerical studies have been carried out using a two dimensional Navier-Stokes solver. It has been inferred through the parametric studies that, in the case of solid rocket motors with uniform port, high ignition peak is observed at high spread rate and low pressure-rise rate. In the case of the port with sudden expansion configuration, high ignition peak is observed at relatively high average spread rate and high-pressure rise rate. These studies are expected to aid the designer in reducing the ignition peak by altering the propellant properties or igniter characteristics without sacrificing the motor performance.

• 한국수소및신에너지학회논문집
• /
• 제20권3호
• /
• pp.256-263
• /
• 2009

The operating range of HCCI engine is narrow due to excessive rate of pressure rise on high load. The fuel stratification is proposed to solve the problem. The purpose of this study is to gain a better understanding of the effects of fuel stratification on reducing the pressure-rise rate at high load in HCCI combustion and to investigate that the operating range is expanded for fuel stratification in the preceding condition of initial temperature and equivalence ratios. The engine is fueled with Di-Methyl Ether (DME) which has unique 2-stage heat release. The computations were conducted using SENKIN application of the CHEMKINll kinetics rate code. Calculation result shows that proper fuel stratification prolongs combustion duration and reduce pressure rise rate.

• KDI Journal of Economic Policy
• /
• 제26권1호
• /
• pp.105-140
• /
• 2004

Korea is entering the class of aging population nations. This paper investigates the extent demographic factors and the aging population affect the saving rate, using an extended life-cycle/permanent-income hypothesis on saving. The results of the tests with Korean household survey data from 1977 to 2002 reveal that real saving rates increase when the duration of lifetime and per household real disposable income rise, and decrease when the growth rate of income and net worth-to-GDP ratio rises. The growth rate of per household real disposable income has negative effects, suggesting that households calculate their life cycle income in a forward looking manner. The elasticities with respect to a change in the lifetime horizon and the growth rate of per household income are 0.58 and -0.03, respectively. A one percent rise in the net worth to GDP ratio reduces the saving rate by 0.3 percent. A one percent rise in per household income increases it by 0.33 percent. The younger-age and the elder-age dependency ratios have insignificant effects on the household saving rate behavior. When Korean life expectancy rises, the private saving rate declines modestly and the government saving rate declines substantially. The economy's real net saving rate declines from 33 percent in 2002 to 30 percent by the year 2030.

• 한국건축시공학회지
• /
• 제9권2호
• /
• pp.93-101
• /
• 2009

Recently, public interest in housing defects, such as construction errors, occupiers' complaints, faults in production, and so on, is increasing. In addition, the construction requirements of high-rise residential buildings have increased, due to the higher prices of urban areas, especially in metropolitan areas. While previous research has focused on the defects occurring in apartment housing complexes, research has not been carried out on the defects occurring in high-rise residential buildings. In this paper, the defects patterns and characteristics of high-rise residential buildings are examined and analyzed and a defect management plan is then suggested. In order to do this, we collected the defects data of high-rise residential buildings recorded by 2,299 of 2,327 occupants. The defect occurrence rate (DOR) in the residential area is 98.8%. The frequency rate of defect occurrence over the total defect occurrence since building completion is 63.28% during the first year, 24.63% (second year), 6.88% (third year), 2.27% (fourth year), and 2.53% (fifth year). The result of correlation analysis between work types showed that there is a relationship between the built-in furniture and electronics (F&E) and painting works, and the F&E and masonry works, such as marble finishing. We expect that this research will assist in the efforts to decrease the number of defects in high-rise buildings.