• 농약과학회지
• /
• 제4권3호
• /
• pp.60-67
• /
• 2000

건조된 한약재 시료인 백삼, 홍삼, 지황, 당귀 및 시호 중에 잔류되어 있는 tolclofos-methyl 및 quintozene의 추출에 microwave 추출법을 이용하고자 Soxhlet 추출법과 추출효율을 비교하여 최적의 추출용매, 추출시간 및 power supply의 강도 등에 대하여 조사하였다. 다섯 가지 한약재 시료에 잔류되어 있는 tolclofos-methyl 및 quintozene을 microwave로 추출하기 위한 용매는 acetone이 가장 효율적이었다. 추출효율은 Soxhlet 7시간 추출과 microwave로 45 watts에서 1분에서 10분 동안 추출한 결과를 비교하였는데 microwave 추출시간을 $3{\sim}5$분으로 한 결과와 Soxhlet 법으로 7시간 추출한 결과는 거의 같게 나타났다. 시료의 종류에 따른 microwave의 추출특성은 인삼은 5분, 다른 한약재들은 3분의 추출에서 Soxhlet추출과 거의 같은 추출 효율을 나타내었다. 잔류분석시 불순물의 방해를 고려한 최적 추출효율을 나타내는 microwave power는 $45{\sim}90$watts로 나타났다. 따라서 tolclofos-methyl 및 quintozene이 잔류되어 있는 다섯 가지 한약재 시료에서의 microwave를 이용한 추출의 최적 조건은 power $45{\sim}90$ watts, 추출용매 acetone, 추출시간 $3{\sim}5$분인 것으로 나타났다.

• 한국해양공학회지
• /
• 제31권3호
• /
• pp.183-188
• /
• 2017

This paper provides numerical results for the estimation of the efficiency of KRISO energy saving devices in the design stage. A finite volume method is used to solve Reynolds averaged Navier-Stokes (RANS) equations, where the SST k-$\omega$ model is selected for turbulence closure. The propeller rotating motion is determined using a rigid body motion (RBM) scheme, which is called a sliding mesh technique. The numerical analysis focuses on predicting the power reduction by the designed KRISO devices (K-DUCT) under a self-propulsion condition. The present numerical results show good agreement with the available experimental data. Finally, it is concluded that CFD can be a useful method, along with model tests, for assessing the performance of energy saving devices for propulsion efficiency improvement.

• Journal of Advanced Marine Engineering and Technology
• /
• 제29권7호
• /
• pp.722-728
• /
• 2005

In this paper, the effects of ethanol blended gasoline on emissions and their catalytic conversion efficiency characteristics were investigated in a multiple-point EFI gasoline engine, The results show that with the increase of ethanol concentration in the blended fuels, THC emissions were drastically reduced by up to thirty percent, And brake specific fuel consumption was increased, but brake specific energy consumption could be improved. However, unburned ethanol and acetaldehyde emissions increased. Pt/Rh based three-way catalysts were effective to reduce acetaldehyde emissions, but had low catalytic conversion efficiency for unburned ethanol. The effect of ethanol on CO and NOx emissions and their catalytic conversion efficiency had close relation to the engine's speed, load and air/fuel ratio. Furthermore fuels blended with thirty percent ethanol by volume could dramatically reduced THC CO and NOx emissions at idle speed.

• 전기학회논문지
• /
• 제65권4호
• /
• pp.561-566
• /
• 2016

In this paper, effective design method of linear induction motor(LIM) for Maglev is proposed in order to maximize system efficiency of Maglev. For the high system efficiency of Maglev, it is important to minimize weight of traction motor. Light weight design by changing materials of core and winding is conducted without changing volume of LIM. For the silicon steel core of primary part for magnetic flux path, iron-cobalt alloy steel with high magnetic saturation characteristic compared to silicon steel is suggested. Moreover, aluminium winding with light weight instead of copper winding is wounded in the widen slot area due to the high magnetic saturation level. For the verification of performance of proposed model, the characteristics are analyzed by using finite element method(FEM).

• 한국유체기계학회 논문집
• /
• 제13권2호
• /
• pp.24-29
• /
• 2010

This paper presents a study on the performance of NASA Rotor 37 with the casing grooves based on three-dimensional numerical analysis. Reynolds-averaged Navier-Stokes equations are solved on a hexahedral grid with the shear stress transport model as a turbulence closure model. The governing equations are discretized by a finite volume method. The validation of the numerical results is performed through experimental data for the total pressure ratio and the adiabatic efficiency. The investigation for an axial compressor with a smooth casing and the casing grooves is carried out to compare the performance parameters, for example, surge margin and efficiency, etc. The surge margin is improved in the case of the casing grooves while remarkable improvement of the efficiency is not produced. The result shows that the casing groove is beneficial to expand the operating range of NASA Rotor 37.

• 동력기계공학회지
• /
• 제15권6호
• /
• pp.95-100
• /
• 2011

In this study, an evaluation equation of energy efficiency of pneumatic driving apparatus is proposed. The evaluation equation is derived from state equation and energy equation of air in a control volume, and, the equation of motion of a moving part of a pneumatic cylinder. As a result, distribution of consumption energy and energy efficiency of pneumatic driving apparatus can be analyzed quantitatively. The effectiveness of the proposed method is proved by a pneumatic cylinder driving apparatus using a meter-out driving method.

• 오토저널
• /
• 제10권4호
• /
• pp.57-65
• /
• 1988

The study of unsteady gas exchange processes in the intake and exhaust systems of four-cylinder, four-stroke cycle internal combustion engine is described in this paper. The calculation model for the intake and exhaust systems is established and solved by the characteristic method for the equations defining these systems. A constant pressure theory is used for modeling branches of intake and exhaust manifolds. The relationship between the volumetric efficiency and the intake, exhaust pressure variation is clarified by simulation of these systems. It is found that the volumetric efficiency mainly depends on the intake pressure during the short period before the intake valves is closed, that the volumetric efficiency is influenced a little by intake chamber volume in the intake and exhaust system.

• International Journal of Fluid Machinery and Systems
• /
• 제4권1호
• /
• pp.140-149
• /
• 2011

For a certain operating point of a horizontal shaft bulb turbine (i.e. volume flow, net head, blade angle, guide vane angle) the efficiency for different pressure levels (i.e. different Thoma-coefficient ${\sigma}$) is calculated using a commercial Computational Fluid Dynamics (CFD-)-code including two-phase flow and a cavitation model. The results are compared with experimental results achieved at a closed loop test rig for model turbines. The comparison of the experimentally and numerically obtained efficiency and the visual impression of the cavitation show a good agreement. Especially the drop in efficiency is calculated with satisfying accuracy. This drop in efficiency in combination with the visual impression is of high practical importance since it contributes to determine the admissible cavitation in a bulb-turbine. It is seen that the incipient cavitation in Kaplan type turbines has no major importance in determing this admissible amount of cavitation.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
• /
• pp.424-427
• /
• 2009

This paper reposes a novel tracking algerian for efficiency improvement of photovoltaic(PV) system using sensor method PV system of sensor method is exactly impossible to track a sun position when insolation is low or rapidly changed by the clouds and fogs. Also, in this case, tracking device is occurred energy consumption by unnecessary operating. This statement of reason, real power of PV system is not increased than fixed PV system in specified location. Therefore, this paper proposes a novel ticking algorithm considered insolation for efficiency improvement of PV system using sensor method And this paper analyzes the generation volume and proves the validity of proposed algorithm as compared with the conventional PV tracking system using sensor method.

• 전기학회논문지
• /
• 제58권11호
• /
• pp.2192-2199
• /
• 2009

This paper proposes a novel tracking algorithm for efficiency improvement of photovoltaic(PV) system using sensor method. PV system of sensor method is exactly impossible to track a sun position when insolation is low or rapidly changed by the clouds and fogs. Also, in this case, tracking device is occurred energy consumption by unnecessary operating. This statement of reason, real power of PV system is not increased than fixed PV system in specified location. Therefore, this paper proposes a novel tracking algorithm considered insolation for efficiency improvement of PV system using sensor method. And this paper analyzes the generation volume and proves the validity of proposed algorithm as compared with the conventional PV tracking system using sensor method.