• 한국분무공학회지
• /
• 제22권4호
• /
• pp.210-217
• /
• 2017

A gasoline direct injection engine has an intake air temperature can be lowered by the fuel vaporization in the combustion chamber increase the volume efficiency is high compression ratio. Therefore, study for injection rate and characteristics which influence mixture formation in combustion chamber is important. Movement of the injector needle has a direct effect on the injection of the fuel, such as formation of cavitation, the fuel injection rate, etc. Therefore, recent studies on the dynamic characteristics of the injector considering the movement of the needle have been reported, but it takes a lot of time and cost to experimentally confirm the movement of the needle inside the injector. In this study, AMESim, a commercial 1-D code, and Star-CCM+, a 3-D CFD code, were used to predict the dynamic performance of the injector with needle motion. In order to predict the movement of the needle under the high pressure, the result of the surface pressure distribution according to the movement of the needle was derived by using the morphing technique of flow analysis. In addition, we predicted the injection rate of the injector considering the movement of the needle in conjunction with the 1-D code. The injection rate of the injector was measured by the BOSCH's method and the results were similar to those of the simulation results. This method can predict the injection rate and injection characteristics and this result is expected to be used to predict the performance of gasoline direct injection engines with low cost and time in the future.

• 대한기계학회논문집B
• /
• 제22권9호
• /
• pp.1317-1324
• /
• 1998

In general, DI gasoline engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance and lower emissions due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, some kinds of methodologies have been adapted in various papers. In this study, a reflector was adapted around the injector nozzle to apply the concept of stratified charge combustion which leads the air-fuel mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally rich to ignite while the lean mixture is wholly introduced into the combustion chamber. The characteristics of combustion is analyzed with the variations of fuel injection pressure and load in a stratified -charge direct injection single cylinder gasoline engine. The obtained results are summarized as follows ; 1. The MBT spark timing approached to TDC with the increase of load on account of the increase of evaporation energy, but has little relation with fuel injection pressure. 2. The stratification effects are apparent with the increase of injection pressure. It is considered by the development of secondary diffusive combustion and the increase of heat release of same region, but proceed rapidly than diesel engine. Especially, in the case of high pressure injection (l70bar) and high load (3.0kgf m), the diffusive combustion parts are developed excessively and results in the decrease of peak pressure than in the case of middle load. 3. The index of engine stability, COVimep value, is drastically decreased with the increase of load. 4. To get better performance of DI gasoline engine development, staged optimizaion must be needed such as injection pressure, reflector, intake swirl, injection timing, chamber shape, ignition system and so on. In this study, the I50bar injection pressure is appeared as the optimum.

• 한국정보통신학회논문지
• /
• 제25권3호
• /
• pp.478-485
• /
• 2021

광 주입 잠금 반도체 레이저의 주입 매개 변수를 조절하여 광학적 복소 신호를 생성 할 수 있다. 그러므로 정확한 주입 매개 변수의 결정은 광학적 복소 신호 생성 기술에서의 핵심 요소이다. 기존의 주입 매개 변수의 추출 이론은 광 주입 잠금 반도체 레이저의 비율 방정식을 사용하며, 이는 locking map 기반의 보간법을 사용하기 때문에 정확한 주입 매개 변수의 추출에 한계가 있다. 이를 해결하기 위하여 비율 방정식의 새로운 해석법을 제안한다. 제안된 해석법은 비율 방정식을 광학적 복소 신호의 생성에 맞게 수정하여 주입 매개 변수를 직접적으로 도출하는 방법이며, 이를 통하여 보간법을 통한 복소 신호 생성 대비 103 배의 오차 감소를 달성하였다.

• 현장농수산연구지
• /
• 제23권1호
• /
• pp.27-30
• /
• 2021

일반적으로 구제역 백신 접종은 유침주사기를 사용하고 있다. 유침주사기 사용 시 근육 조직 및 림프구에 병변이 생기는 이상육이 발생하고 이는 소비자의 불만제기와 국내산 돼지고기(한돈)의 이미지 악화와 관련된다. 그 대안으로 무침주사기 개발이 이루어지고 있다. 본 연구는 무침주사기를 이용한 구제역 백신 접종 시 이상육 발생빈도를 조사하여 무침주사기의 활용성을 검증하기 위해 실시했다. 실험결과 무침주사기 사용 시 이상육의 발생이 유침주사기 사용 대비 유의적으로 낮았다(36 vs. 16%, p < 0.05). 따라서 무침주사기를 이용한 구제역 백신 접종 시 이상육 발생을 낮춰 돈육 품질을 높이고 소비자 불만을 감소시킬 수 있을 것으로 판단된다. 추가 연구로 무침주사기의 항체형성률, 작업효율성, 경제적 비용 등을 조사하고 무침주사기의 활용성을 검증할 필요가 있다.

• 대한간호학회지
• /
• 제27권3호
• /
• pp.510-519
• /
• 1997

The purpose of this study was to determine the effect of regular exercise during dexamethasone injection on the body weight, weight of hindlimb muscles and adrenal gland in Young rats. 80-100g Wistar rats were divided into control, exercise, dexamethasone injection(dexa), and exercise during dexamethasone injection(D+E) group. The dexa group received daily subcutaneous injection of dexamethasone at a dose of 5mg/kg body weight for 10 days. The exercise group ran on a treadmill for 60min /day(20 minutes every 4 hour) at l0m/min and a 10$^{\circ}$ grade. The control group received daily subcutaneous injection of normal saline at a dose of 5mg /kg body weight for 10 days. The D+E group ran on a treadmill for 60min /day (20 minutes every 4 hour) at 10m/min and a 10$^{\circ}$ grade. Body weight of both control and exercise group increased significantly until 10 days, that of both dexa and D+E group decreased significantly, resulting in 79.47 and 78.75% decrease respectively compared to the first day of experiment. Body weight and muscle weight of the soleus, plantaris and gastrocnemius decreased significantly with dexamethasone injection. Relative weight of the plantaris and gastrocnemius of the dexa group decreased significantly compared to that of the control group. Body weight and muscle weight of the gastrocnemius of the exercise group increased significantly, and the muscle weight of the soleus and plantaris tended to increase. The Relative weight of the plantaris was comparable to the control group and that of the soleus and gastrocnemius tended to increase in the exercise group. Body weight and muscle weight of the soleus and plantaris of the D+E group showed a tendency to increase, and muscle weight of the gastrocnemius increased significantly compared to the dexa group. The Relative weight of the soleus and gastrocnemius tended to increase, and that of the plantaris of the D+E group increased significantly compared to the dexa group. Body weight, muscle weight and relative weight of the soleus, plantaris and gastrocnemius of the D+E group did not recover to that of the control group. Adrenal gland weight of the dexa and D+E group tended to increase, and that of the exercise group increased significantly. From these results, it can be suggested that regular exercise during dexamethasone injection might attenuate the decrease of body weight and hindlimb muscle weight induced by the dexamethasone injection.

• 설비공학논문집
• /
• 제24권5호
• /
• pp.377-384
• /
• 2012

Vapor injection technique has been applied to prevent performance degrdation of a heat pump at low ambient temperatures. In this study, the heating performance of a heat pump with a variable speed injection scroll compressor using R-410A was investigated by applying sub-cooler vapor injection(SCVI) and flash tank vapor injection(FTVI). The heating performance of the heat pump was measured by varying compressor frequency and outdoor temperature. The heating capacity of the FTVI system was 8~10% higher than that of the SCVI system at all operating conditions. On the other hand, the heating performance improvement with the increase in the compressor frequency was more prominent in the SCVI system than in the FTVI system.

• 동력기계공학회지
• /
• 제16권3호
• /
• pp.10-15
• /
• 2012

Recently we have a growing interest in environmental pollution and alternative energy. Diesel engine is generally used to produce the power on the ground and the sea. However, the combustion characteristics are changed on account of the wear of fuel system and the altered ambient condition of the combustion chamber by the increment of the engine operation hour. Therefore combustion characteristics on fuel injection timing are experimentally investigated to find out the optimum fuel injection timing in the case of the aged diesel engine using biodiesel blend oil. Cylinder pressure, rate of pressure rise, rate of heat release and combustion gas temperature are risen by the advancing fuel injection timing, while the exhaust gas temperature and soot emission level are decreased by the advancing of fuel injection timing. The least specific fuel oil consumption is indicated at BTDC $26^{\circ}$ CA on the 75%load and at 1800rpm.

• Journal of Advanced Marine Engineering and Technology
• /
• 제35권3호
• /
• pp.317-322
• /
• 2011

This work has investigated the exhaust emissions such as Total Hydrocarbon (THC), Nitrogen Oxides(NOx), and Particulate Matter (PM) characteristics emitted from the tail-pipe of a continuously variable valve timing (CVVT) gasoline-fueled engine with different intake valve opening timings and injection pressures at the part load condition. Valve overlap period was varied from $40^{\circ}CA$ to $10^{\circ}CA$ and fuel injection pressure was increased from 3.5 bar to 5.0 bar. THC and NOx emissions decreased as intake valve opening timing was advanced regardless of fuel injection pressure. When the fuel was injected with the condition of 5.0 bar at all of valve overlap ranges, THC levels were reduced by 55%. NOx concentrations were diminished about 75% as valve overlap increased. PM size distributions were analyzed as bi-modal type of the nucleation and accumulation mode. Comparing with fuel injection pressures, PM emission levels were decreased at high pressure injection of 5.0 bar condition.

• 한국안전학회지
• /
• 제27권1호
• /
• pp.49-54
• /
• 2012

The objective of this study is to investigate the capacity of epoxy injection method using low pressure mixed with high pressure. Injection depth test and flexural strength test were respectively performed on $40{\times}45{\times}35$ cm and $100{\times}10{\times}40$ cm specimens. Considered as the test variables were injection type(low pressure, low and high pressure), crack width(0.25 mm, 0.50 mm), injection direction(upper, lower, side), and epoxy viscosity(low, medium, high). Test results showed that low viscosity epoxy injection depth of injector using low pressure mixed with high pressure for upper direction were 23 cm and tension strength of crack face repaired by injector using low pressure mixed with high pressure was larger than that of concrete.

• Journal of Advanced Marine Engineering and Technology
• /
• 제24권6호
• /
• pp.110-119
• /
• 2000

In this paper, an experimental study is carried out under the operating conditions of low speed and rapid acceleration in order to investigate and improve the response characteristics of a turbocharged diesel engine with radial turbine driven by exhaust gas. A rapid acceleration for investigating the response performance is applied to the fuel-pump rack of the engine from 0-10% to 0-40% in steps of 10%, and accelerating time of 1, 2 and 3 seconds is applied to the engine. Further experiment for improving the low speed torque and acceleration performance is also performed by means of injecting air into the inlet manifold at compressor exit during the period of low speed and application of a rapid acceleration. The effects of air injection on the response performance are represented at subjected engine speed with the changes of response performance factors such as air injection pressure, air injection period, accelerating rate, accelerating time and load. From the experimental results obtained throughout this study, it is shown that air injection into the inlet manifold at compressor exit is closely related to the improvement of low speed and acceleration performance of a turbocharged diesel engine.