• 한국분무공학회지
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• 제28권4호
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• pp.169-175
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• 2023

Multi-injection scheme is being applied to GDI combustion to reduce PM and PN emission to meet the EU7 regulation. However, very short injection duration encounters the ballistic injection region, which injection quantity does not increase linearly with injection duration when applying multi-injection. In this study, numerical studies were conducted to reveal the cause of ballistic injection and the effect of design parameters on ballistic region using 1-D simulation, AMESim. Injection rate and injection quantity were compared with experiment to validate the established model, which showed the accuracy with 10% error. The model revealed that the tendency of ballistic region coincides with the needle motion behavior, which means that parameters at the upper part of needle such as electro-magnetic force, needle spring force and needle friction force have dominant effect on ballistic injection. To figure out the effect of electro-magnetic and needle friction force on ballistic, those parameters were varied to plus and minus 10% with model. The result showed that those parameters clearly changed the ballistic region characteristics, however, the impact became insignificant for outside of ballistic region, which means that the ballistic injection is mainly influenced by initial motion of injector needle.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.55-64
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• 2014

This work was investigated on pilot injection strategy of blended fuels(Diesel-DME) for combustion and emissions in a single cylinder direct injection compression ignition engine. Diesel and DME were blended by the method of weight ratio. Weight ratios for diesel and DME were 95:05 and 90:10 respectively. dSOI between main and pilot injection timing was varied. A total amount of injected fuels(single injection) was adjusted to obtain the fixed BMEP as 4.2 bar in order to compare with the fuel conditions. Also, the amount of pilot injection fuel was varied by 5%, 10% and 20% of total injection fuel. The engine was equipped with common rail and injection pressure is 700 bar at 1200 rpm. As a result, when mixing ratio increase, indicated thermal efficiency was increased in comparison with DD 100 and CO, THC and smoke were lower than DD 100. The influence of reducing NOx by pilot injection was more effective than DD 100. When pilot injection quantity increase, abrupt increase of NOx was occured at pilot injection quantity of 20%.

• 대한기계학회논문집
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• 제17권10호
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• pp.2590-2600
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• 1993

The present paper describes numerical predictions for the film cooling effectiveness from a row of hole at various injection ratios and injection alngles.Numerical calculations were performed to investigate film cooling effectiveness and the characteristics of flow and temperature distributions in the region near the downstream of injection hole including the region of adverse pressure gradient. The elliptic 3-dimensional governing equations with variable thermal properties were solved by SIMPLE algorithm. The results showed that the presence of adverse pressure gradient in the region near the downstream of injection hole induces large temperature gradient. At injection angle of $35^{\circ}$ the average film cooling effectiveness was increased as increased of injection ratio up to 1.0. At injection angle of $90^{\circ}$ however, the average film cooling effectiveness was decreased from injection ratio larger than 0.4.

• 한국분무공학회지
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• 제23권2호
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• pp.96-101
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• 2018

The purpose of this study is to investigate the effect of water injection on combustion characteristics of gasoline direct injection (GDI) engine with turbo-charger under low-load operating condition. The test engine used in this study has four-cylinder and 10.2 of compression ratio. In order to study the effect of water injection ratio on combustion characteristics, the water was injected into the intake port from 10% to 50%, based on fuel injection quantity. From the experiment, it revealed that the water injection induced the improvement of fuel economy because of the advance of spark-timing by the reduction of in-cylinder temperature. In addition, the water injection caused the prolong of extension of the ignition delay and slight increase of burn duration.

• 한국구조물진단유지관리공학회 논문집
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• 제10권1호
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• pp.115-122
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• 2006

현재 콘크리트 구조물의 보수에서 품질의 검사 기준이 없는 상태에서, 단순한 경험에 의한 보수는 문제점을 가지고 있다. 이 문제점을 개선하기 위하여 이 논문은 균열폭과 주입량, 균열폭과 주입시간, 균열폭과 주입압력, 균열폭과 주입압력과 주입시간, 구조물 규모와 주입량, 구조물 별 균열 위치와 주입량, 균열폭 및 구조물 두께와 주입시간과의 관계를 분석하였다. 분석한 결과에서 얻은 자료는 콘크리트 구조물의 보수에 대한 체계적인 품질관리에 도움이 될 것이라 생각한다.

• 한국구조물진단유지관리공학회 논문집
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• 제10권6호
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• pp.191-197
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• 2006

본 논문은 터널 콘크리트 구조물의 보수를 위한 무기계 균열주입기술의 표준화에 관한 연구이다. 본 연구를 위하여 균열보수공사가 필요한 터널 라이닝 및 박스 구조물을 선정하여, 균열폭에 따른 주입량, 주입시간 및 주입압력, 주입압력과 주입시간, 구조물 규모에 따른 주입량, 구조물별 균열 위치에 따른 주입량, 균열폭 및 구조물 두께와 주입시간의 관계에 관하여, 현장 조사와 시험평가를 수행하여 구조물의 종류 및 균열의 크기에 따른 균열보수재의 주입압력, 주입량 및 주입시간 등을 명확히 파악하였다.

• 한국분무공학회지
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• 제21권1호
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• pp.20-28
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• 2016

This paper presents an experimental study on the GDI injector with Bosch method. The injection characteristics, such as the injection quantity, the injection rate, the maximum velocity of the nozzle exit and the injection delay were studied through the change of the injection pressure, the tube pressure and energizing duration in injection rate measurement device using nheptane. The injection quantity is increased by increasing injection pressure, decreasing tube pressure or increasing energizing duration. As the difference of the injection quantity changed, the shape of injection rate was moved with a constant form. The maximum velocity of the nozzle exit showed a tendency to increase as the injection pressure is increased. However, tube pressure did not affect. Overall, it was confirmed that the closing delay is longer than the opening delay in all conditions. As the injection pressure increased, the result has a tendency to decrease the closing delay, it did not affect the opening delay. Reduction of the closing delay showed the reduction of the injection duration. the tube pressure and energizing duration did not affect the injection delay (opening delay, closing delay).

• 생약학회지
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• 제6권1호
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• pp.39-42
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• 1975

Influence of Eucommiae Cortex in Korea on the blood pressure of the rabbit was examined, 1) The intravenous injection of 3 mg/kg, 10 mg/kg and 30 mg/kg of the water extract to the rabbit decreased its blood pressure to $9.7\;{\pm}\;1.9,\;26.4\;{\pm}\;1.7\;and \;35.5\;{\pm}\;2.7\;mmHg$. respectively. 2) The intravenous injection of 10 mg/kg of the water extract did not show any remarkable influence to the blood pressure caused by the intravenous injection of acetylcholine $10^{-8}\;g/kg\; and \;10^{-7}\;g/kg$. 3) The intravenous injection of the water extract after the intravenous injection atropine 2mg/kg did not show any remarkable change to the blood pressure 4) The intravenous injection of the water extract after the intravenous injection of propranolol 2mg/kg slightly decreased the blood pressure.

• 한국분무공학회지
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• 제24권4호
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• pp.171-177
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• 2019

This paper describes numerical study of combustion characteristics in CNG(compressed natural gas) DI(direct injection) engine using gaseous sphere injection model. Simulations were conducted using KIVA-3V Release 2 code. Gaseous sphere injection model, which is modified model of liquid fuel injection, was used to simulate the CNG direct injection. Until now, a very fine mesh smaller than the injector nozzle has been required to resolve the gas-jet inflow boundary. However, the gaseous sphere injection model simulates gaseous fuel injection using a coarse mesh. This model injects gaseous spheres as in liquid fuel injection and the gaseous spheres evaporate together without the latent heat of evaporation. Therefore, it does not require a very fine mesh and reduce calculation time. Combustion simulation were performed under various injection timings and injection pressures.

• 한국분무공학회지
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• 제27권4호
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• pp.181-187
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• 2022

For carbon neutrality, direct-injection hydrogen engines are attracting attention as a future power source. It is essential to estimate the transient injection rate of hydrogen for the optimization of hydrogen injection in direct injection engines. However, conventional injection rate measurement techniques for liquid fuels based on the injection-induced fuel pressure change in a test section are difficult to be applied to gaseous fuels due to the compressibility of the gas and the sealing issue of the components. In this study, a momentum flux measurement technique is introduced to obtain the transient injection rate of gaseous fuels using a force sensor. The injection rate calculation models associated with the momentum flux measurement technique are presented first. Then, the volumetric injection rates are estimated based on the momentum flux data and the calculation models and compared with those measured by a volumetric flow rate meter. The results showed that the momentum flux measurement can detect the injection start and end timings and the transient and steady regimes of the fuel injection. However, the estimated volumetric injection rates showed a large difference from the measured injection rates. An alternative method is suggested that corrects the estimated injection rate results based on the measured mean volumetric flow rates.