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The research shows the experimental results of the powerpack for optimization of combustion characteristics and generating power according to operating conditions. The powerpack used in this research consists of 2-stroke linear engine, linear generator and air compressor parts and was used for confirming the generating power. For identifying the combustion characteristics and generating power of linear engine, fuel input calorie, spark timing delay, equivalence ratio, electric load and air gap length was varied respectively. Also generating power was confirmed at each operating conditions. During the all experiments, intake air was inputted under the wide open throttle. Mass flow ratio of air and fuel were changed by using mass flow controller. Thereafter, fuel and air was premixed by the premixture device. The pre-mixed gas was supplied directly into front and rear cylinder of the linear engine. As a result, piston frequency in-cylinder pressure were varied at each conditions according to parameters affecting the combustion such as fuel input calorie, resistive load, spark timing delay and equivalence ratio. Consequently, these had an effect on generating power.
The performance characteristics of a variable displacement vane pump was analysed in order to apply to automatic transmission by using Pumplinx v3. Discharge flow rate, pressure ripples and cavitation generation rate of vane oil pump were investigated according to rotation speed, operating temperature and operating pressure. As a result, pressure ripples increased with a rise of rotation speed and decreased with a rise of oil temperature. Besides, discharge flow rate increased linearly with rotation speed. Also, discharge flow rate increased as oil temperature was reduced. In addition, the cavitation occurs at the inlet port of vane pump. The cavitation generation rate increased significantly at 3,000 RPM. Therefore, it is determined that the first variable timing of displacement vane pump is 3,000 RPM or less.
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본 연구에서는 아시아의 33개 국가를 대상으로 1900년부터 2018년까지 발생한 가뭄피해에 대한 피해예측 산정식을 개발하였다. 가뭄피해 예측 산정식의 매개변수로는 가뭄피해 데이터와 국가별 경제지표와 기초지표를 고려하였다. 가뭄피해 데이터는 가뭄피해 발생횟수, 인명피해사망, 인명피해영향, 피해금액를 국가별 경제지표 및 기초지표는 GDP, 면적, 인구수로 총 7개를 선정하였다. 가뭄피해 예측 산정식의 수정된 R²은 가뭄피해 발생횟수이 0.794, 가뭄의 피해액이 0.916으로 높은 설명력을 가지고 있는 것으로 분석하였다. 따라서, 본 연구의 결과는 가뭄의 불확실한 피해규모를 예측하기 위해 아시아 국가의 정량적 피해규모를 산정하여 재난관리를 위한 지표로서 활용 가능할 것으로 판단된다. In this study, 33 different countries in Asia developed a predictive of damage by analyzing the drought that occurred in 1900 to assess the damage caused in 2018. The parameters of the estimation equation for drought damage were drought damage data, national economic indicators, and basic indicators. For drought damage data, seven national economic indicators and basic indicators were selected for the number of cases of drought damage, death toll, impact of human casualties, and amount of damage. The revised R2 of the estimation formula for drought damage was analyzed to have high explanatory power with a drought damage rate of 0.794, and the drought s damage was 0.916. Therefore, the results of this study are expected to be used as an index for disaster management by calculating the quantitative damage scale of Asian countries to predict the uncertain damage scale of drought.
본 연구에서는 자동변속기용 가변형 베인 펌프의 성능특성을 연구하기 위하여 3D 해석프로그램을 이용하여 베인 펌프의 성능에 대하여 해석적 연구를 진행하였다. 이를 수행하기 위하여 회전수 변화에 따라 베인 펌프의 토출압력, 로터와 베인에서 동력 변화 및 펌프 내에서 캐비테이션 발생유무를 확인하였다. 해석결과, 회전수가 증가할수록 압력 맥동이 커졌으며 저속조건에서는 토출측에서 오일의 역류가 많아져 압력맥동의 진폭에 영향을 주는 것으로 나타났다. 또한 베인과 로터의 동력은 회전수가 증가함에 동시에 증가하는 것으로 나타났으며 이로 인해 고속 운전조건에서 캠링과 베인 날개 끝부분에 캐비테이션이 발생하여 베인과 로터의 동력이 급격하게 증가하는 것을 확인할 수 있었다. Theocratical study on the performance characteristics of the variable displacement vane pump by using the 3D interpretative program. The performance analysis was carried out with the rotation speed, and the total outlet pressure, rotor and vane power, cavitation was investigated. As a result, pressure ripples increased with a rise of rotation speed. At low rotation speed condition, the oil flowed backward from the discharge side, and it had an effect on the amplitude of the pressure ripples. Besides, the vane and rotor power increased as the rotor rotation speed rose. Moreover, in high speed conditions, some cavitation occurs at the end of vane wing and cam ring rapidly, resulting an increased power consumption.
The performance characteristics of a variable displacement vane pump into the automatic transmisson were analysed by using Pumplinx v3. Rotor and vane power, cavitation of variable vane pump were investigated according rotation speed and temperature difference. As a result, pressure ripples increased with a rise of rotation speed. In over 3000 rpm, increasing the rotation speed of the vane pump showed increasing rotror power consumption. Besides, cavitation occurs on the inlet part of vane at end of vane wing and disappear on the outlet part of vane. Due to the temperature rise in the operating temperature(85°C), showed smaller changes in the consumption of power, But winter start-up temperature(-10°C)showed a much power consumption pressure ripples increased with a rise of rotation speed. In over 3000 RPM, cavitation occurs on the inlet part of vane at end of vane wing and disappear on the outlet part of vane.
In the future, the compact powerpack was needed because the existing rechargeable batteries cannot provide high energy density and required operational duration. As an alternative, the linear engine was satisfied with compact, durability and had light weight. In this study, prototype ceramic free-piston linear engine combined with a linear alternator was designed to produce electric power for portable usage. It has a bore size of 30 ㎜ and maximum stroke of 33 ㎜. The engine was fueled with liquefied petroleum gas consisting of 98% propane. Its electric power generation performance was tested as a function of the spark timing and equivalence ratio. The equivalence ratio of the mixture was varied from 0.8 to 1.2, while the spark timing was varied as 0.5, 1.0, 1.3, 1.5 and 2,0 ㎳ that the piston passes the first photo sensor. As a result, the maximum electric power was generated when equivalence ratio and ignition timing was 1 and 1.5 ㎳, respectively. Then, the piston velocity was 58㎐.