• Journal of Korean Society of Forest Science
• /
• v.99 no.2
• /
• pp.197-203
• /
• 2010

The data of average temperature, average relative humidity, precipitation and average wind speed were collected from 674 meteorological stations in China. A specific procedure that processes original data into a new data format needed in forest fire danger rating forecast system of China was introduced systematically, and the feasibility of this method was validated in this paper. In addition, a set of meteorological data processing software was constructed by the secondary development of GIS in order to realize automation of processing data for the system. Results showed that the approach preformed well in handling temperature, average relative humidity and average wind speed, and the processing effect of precipitation was acceptable. Moreover, the automated procedure could be achieved by GIS and the working efficiency was about 3 times as much as that of manual handling. The informationization level of processing meteorological data was greatly enhanced.

• Journal of Mechanical Science and Technology
• /
• v.19 no.9
• /
• pp.1821-1832
• /
• 2005

This study realizes the conceptual method to predict combustion instability in actual full-scale combustion chamber of rocket engines by experimental tests with model (sub-scale) chamber. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions, and hot-fire test procedures were followed to obtain stability boundaries. From the experimental tests, two instability regions are presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for combustor designers. It is found that instability characteristics in the chamber with the adopted jet injectors can be explained by the correlation between the characteristic burning or mixing time and the characteristic acoustic time: In each instability region, dynamic behaviors of flames are investigated to verify the hydrodynamically-derived characteristic lengths of the jet injectors. Large-amplitude pressure oscillation observed in upper instability region is found to be generated by lifted-off flames.

• Fire Science and Engineering
• /
• v.11 no.1
• /
• pp.47-54
• /
• 1997

Using high tensile steel plate makes the vehicle body stiffness lower even though it can lessen the fuel consume rate in application of weight reduction. The crack which happens arround vehicle window glass is brought about due to fatigue with low torsional stiffness. The paper presents a most suitable way to increase torsional stiffness using elasticity theory. Also the result of this study shows good agreement with FEM and experiments. We used a passenger car for calculation in this paper. Because we can apply the result of this study to fire engine as well as passenger car.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2012.04a
• /
• pp.117-120
• /
• 2012

현재 국내에서 발생하는 화재의 대부분은 밀집한 건물에 발생하는 화재이다. 이러한 건물화재의 특징은 초기진화에 실패할 경우 인접한 건물로 화재가 번져 대형 화재로 이어지며, 이로 인한 피해도 급증하게 된다. 또한 소방차 출동 시 도로여건이나 주 정차 차량 등 다양한 진입 장애물 등으로 화재지역으로 신속한 접근이 어려운 경우가 많다. 따라서 실효적 화재 진화 성능을 가진 방수시스템을 탑재한 소형화된 미니 소방차를 개발하고자 하며 아울러 고지대나 산림 화재의 초기 대응을 위해 험로(산악지형)에서도 주행이 가능한 ATV(All Terrain Vehicle)를 적용하고자 한다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2012.04a
• /
• pp.58-61
• /
• 2012

엔진나셀 화재를 둔각물체에서 분사된 연료제트 화염으로 모사하여 화염안정화 및 소화특성을 조사하기 위해 실험과 수치해석을 수행하였다. 연료제트는 공기유동에 동측류인 경우와 대향류인 경우에 사각의 둔각물체에서 분사하였고, 소화약제는 이산화탄소와 질소를 사용하여 공기유동에 희석시켜주었으며 연료로는 메탄을 사용하였다. 본 실험의 결과를 해석하고 보충하기 위하여 LES(Large Eddy Simulation)을 기반으로 하는 FDS(Fire Dynamics Simulator)를 이용하여 비반응 유동장에서의 혼합특성과 둔각물체 후류의 유동특성을 살펴보았다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2009.04a
• /
• pp.180-187
• /
• 2009

한국형 헬기 개발사업 (KHP)에서 개발 중인 한국형 기동 헬기(KUH)의 엔진실에 적용되는 소화시스템의 성능평가를 수행하였다. 사용된 소화약제는 할론 1301 이며, 국방규격에 맞게 설계 되었다. 실물모형의 엔진 목업을 제작하여 소화시스템을 배치하고, 화재 소화실험과 할론 농도 측정 실험을 수행하였다. 실험 결과 설계된 소화시스템은 엔진실 내부의 화재를 효과적으로 소화시켰으며, 국방 규격에서 요구하는 분사 시간 조건 및 농도조건을 만족함을 확인 하였다.

• Journal of the Korean Institute of Gas
• /
• v.15 no.6
• /
• pp.28-33
• /
• 2011

The purpose of this paper analyzes and studies to improve the failure cases on the computer that one of electronic control elements for engine in liquified petroleum gas vehicle. The first case, it certified the non-starting phenomenon of engine that it's electronic control unit didn't control the fuel for idle speed actuator because of no given action signal in slow-cut solenoid valve. The second case, it knew the bad condition phenomenon of engine and back-fire by the wire melting of ignition coil and firing of transistor being inside ECU. The third case, it certified the action stoping phenomenon of engine and malfunctioning signal for engine ECU because of leakage of current and an excess current by moisture inflowing inside ECU curcuit plate. Therefore, it is thought that will elevate the durability and reliability of engine computer throughout procure of quality.

• Journal of Mechanical Science and Technology
• /
• v.20 no.6
• /
• pp.874-881
• /
• 2006

Combustion stability characteristics in actual full-scale combustion chamber of a rocket engine are investigated by experimental tests with the model (sub-scale) chamber. The present hot-fire tests adopt the combustion chamber with three configurations of triplet impinging-jet injectors such as F-O-O-F, F-O-F, and O-F-O configurations. Combustion stability bound-aries are obtained and presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio. From the experimental tests, two instability regions are observed and the pressure oscillations have the similar patterns irrespective of injector configuration. But, the O-F-O injector configuration shows broader upper-instability region than the other configurations. To verify the instability mechanism for the lower and upper instability regions, air-purge acoustic test is conducted and the photograph or the flames is taken. As a result, it is found that the pressure oscillations in the two regions can be characterized by the first impinging point of hydraulic jets and pre-blowout combustion, respectively.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3311-3316
• /
• 2007

To analyze the influence of valve overlap period on a backfire occurrence, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and backfire limit equivalence ratio defined as fuel-air ratio equivalence ratio at which backfire occurs is examined according to various valve overlap period. The MCVVT is the system to control valve overlap period by mechanical device. It is estimated that the lower valve overlap period has the higher backfire limit equivalence ratio though the same energy is supplied. When the valve overlap period is changed from 30$^{circ}$ CA to 0$^{circ}$ CA, backfire limit equivalence ratio is increased 74%, approximately. It means that valve overlap period is concern in backfire occurrence, and may be one of the methods for controlling back fire occurred in a $H_2$ engine.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.7
• /
• pp.1123-1130
• /
• 2004

Numerical simulations have been carried out to investigate the effect of nozzle hole geometry on the combustion characteristics of the large diesel engine. 6S90MC-C. Spray and combustion phenomena were examined numerically using FIRE code. Wane breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation processes. Predictions on the cylinder peak pressure and NOx emission were first verified with the experimental data to confirm the reliability of numerical calculations. The comparison results showed good agreements within the range of 0.64% and 4.6% respectively. Finally, the effects of fuel spray angle and diameter on the engine performance were investigated numerically to find the optimum nozzle hole geometry considering fuel consumption, NOx emission and heat flux of the combustion chamber wall. It was concluded that the combustion gas recirculation in cylinder by changing fuel injection direction is an effective method to reduce NOx emission by about 10% with increasing fuel oil consumption, 1.4% in a large diesel engine.