• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.4
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• pp.160-170
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• 1997

The objective of this study is to investigate the atomization characteristics and the performance characteristics of a C. I. engine by using the changes of the injection nozzle type and the ultrasonic-energy-added system. In order to evaluate the effect of ultrasonic energy and of change of injection nozzle type in the performance characte- ristics of a diesel engine, measurements of droplet size of diesel fuel were carried out by using Malvern system. In all types of injection nozzles, SMD of the ultrasonic- energy -added diesel fuel was smaller than that of the conventional diesel fuel and the more injection pressure increased, the more SMD decreased. There was a small increase in SMD with the distance from injection nozzle under all conditions of the injection nozzle types. The minimum SMD was found in the injection nozzle of B type. In the diesel engine test, there were three results about the engine performance. Compared with the injection nozzle of A type, B type had excellent effects in the engine performance. The most excellent effects about the engine performance were obtained in the case of ultrasonic-energy-added diesel fuel. In addition, the torque diagram in the case of ultrasonic-energy-added diesel fuel was more stable and periodical than others.

• Journal of ILASS-Korea
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• v.5 no.4
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• pp.40-46
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• 2000

To understand the basic the structure of the spray field and to obtain the initial conditions for computational models for shear coaxial twin-fluid injectors. the atomization characteristics under different flow and geometric conditions were examined. The spray characteristics such as SMD, mean axial and radial velocities, Dia. of droplets and volume flux with a P.D.P.A. Water and nitrogen gas under atmospheric conditions were used as a test fluids. The drops produced by shear coaxial injectors continue to disintegrate along the spray axis and decrease their sizes. SMD was the maximum at the spray center of spray and decreased with increasing radial distance. The results of this parametric study showed that SMD decreased with increasing gas injection velocity as well as with decreasing liquid injection mass flow rate, The relative velocity between gas and liquid flow played a significant role resulted in decreasing SMD and in spreading the spray. Recessing the liquid orifice resulted decreasing SMD and a spreading the spray. Recess of liquid orifice by 5.0mm showed best atomization characteristics in this experiment. Although drop diameter changes, shear coaxial injector sprays had constant velocity and exhibited a high degree of radial symmetry.

• Journal of ILASS-Korea
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• v.9 no.2
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• pp.24-33
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• 2004

The effect of the working fluid flow conditions and nozzle geometry on the spray performance of a twin-fluid nozzle used in Selective Catalytic Reduction is investigated experimentally. The liquid pressure is varied in the range of 0.3atm to 1.5atm and the air pressure is varied from the 0.5atm to 3.0atm. relative position between liquid nozzle(internal nozzle) and air nozzle(external nozzle) tip changes front 1mm inside the air nozzle to 1mm outside the air nozzle. The orifice diameter of the air nozzle is varied with 5mm. 6mm and 7mm. Spray visualization is realized with CCD-Camera. SMD(Sauter Mean Diameter) and mean particle velocities are measured by PDPA(Phase Doppler Particle Analyzer) under various experimental conditions. The measuring point is 300mm away from the nozzle tip in the downstream spray. The experimental results are that spray angle is depended air flow rate because nozzle diameter, air pressure and nozzle tip relative positions are related air flow rate. SMD is depended air flow rate and water flow rate. Also, SMD is increased when water flow rate is bigger. SMD is decreased when Air flow rate is bigger.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1459-1466
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• 2004

The purpose of this study is to investigate the effect of swirler angle and the aspect ratio of swirl chamber of nozzle on the characteristics of single and twin spray. The characteristics of sprays have been investigated by measuring the spray angle, droplet size and velocity. Visualization of spray was conducted to obtain the spray angle and breakup process. The spray characteristics such as droplet size and velocity were measured by Phase Doppler Anemometry(PDA). It was found that the spray angle was increased with increasing the swirler angle. For both sprays, the axial velocity and SMD were decreased with increasing the swirler angle. It was also shown that the axial velocity and SMD were decreased with increasing the aspect ratio of swirl chamber, but for the twin spray, the axial velocity and SMD were not influenced significantly by the changing the aspect ratio of swirl chamber. The effect of swirler angle on the spray characteristics was greater than the aspect ratio of swirl chamber for single spray. The nozzle pitch was one of the important factors affecting the spray characteristics of twin spray.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.371-376
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• 1995

Computer vision is applicated to measure the position and orientation of the SMD on 8mm Camcoder PCB and advanced image processing algorithms for high accuracy and real time processing are proposed. Illumination conditions are optimized for the best image formation and a set of LEDs is used as economic illuminator, which is regarded as a summation of many point sources. Conctete optical system is constructed and the performance of the proposed algorithm is verified by several experiments.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.124-127
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• 2010

본 논문에서는 소형 SMD 솔레노이드 형태의 RF 칩 인덕터의 최적 구조를 도출하였다. $1.0\times0.5\times0.5mm^3$ 크기의 96% $Al_2O_3$ 코아는 $40{\mu}m$ 직경의 구리 코일을 4회 권선하여 8.57nH의 인덕턴스, 37.6의 품질계수와 6.05GHz의 SRF를 가진다. $40{\mu}m$ 직경의 구리 코일을 0.35mm 솔레노이드 길이로 중앙에 6회 권선하였을 경우가 250MHz11.2nH의 인덕턴스, 29.8의 품질계수와 5.6GHz의 SRF로 가장 우수하였다.

• New & Renewable Energy
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• v.5 no.3
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• pp.22-25
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• 2009

For increasing the output voltage, six SMD(surface mount device) type AlGaAs/GaAs solar cells were connected in series. The electrical properties of the array were measured and compared with one sun (100 mW/$cm^2$) and indoor light (480 lux) conditions. Under one sun condition, output power was 21.57 mW and it was $14.67\;{\mu}W$ under indoor light condition. Under the indoor light condition, the intensity of the light is very low compared to one sun condition. Thus the Voc(open circuit voltage) and Isc (short circuit current) of the sample under indoor light condition decreased very much compared to that of under the one sun condition. This kind of solar cell power supply can be used as a power source for ubiquitous sensor network (USN).

• Industrial Engineering and Management Systems
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• v.12 no.4
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• pp.330-335
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• 2013

A surface mount device (SMD) assembles electronic components on printed circuit boards (PCB). Since a component assembly process is a bottleneck process in a PCB assembly line, making an efficient SMD plan is critical in increasing the PCB assembly line productivity. Feeder assignment is an important part of the SMD plan optimization. In this paper, we propose a feeder re-assign improvement algorithm for a specific type of SMD machine with a piano type multi-head gantry. Computational results on some real-world benchmark data sets show the effectiveness of our proposed algorithm.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.131-135
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• 2001

The atomization characteristics of an annular liquid (water) sheet of small radius with a core gas (air) flow were studied. Different sizes of annular gaps (0.2, 0.4 and 0.8 mm) were tested to find the effect of liquid sheet thickness on SMD. The inner diameter of the gas port for the core gas flow was 4 mm. Cross-section averaged SMD was measured for various liquid and gas velocities. Regions of the SMD decrease with the increase of the liquid velocity always existed regardless of the liquid sheet thickness. This attributes to the transition of the flow patterns of spray and also to the aerodynamic interaction between the atomizing gas and the ripples on the liquid sheet surface.

• Journal of ILASS-Korea
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• v.4 no.2
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• pp.40-46
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• 1999

Experimental investigation of unsteady impinging diesel spray on the flat plate have been carried out using high speed camera and Malvern system. The density ratios of ambient gas to diesel fuel were varied using $N_2$ and Ar gas in the case of 14.9, 21.2, 28.4, 35.1, 40.4, and 50.1. With the increase of gas density ratio, the radial penetration is decreased due to the resistance of the ambient gas. With the increase of the gas density ratio and the distance between nozzle tip and flat plate, the height of spray is increased due to the entrance and circulation. With the increase of gas density ratio, SMD is decreased on the nearby position at the center of flat plate, but SMD is increased on the far position. As the distance between nozzle tip and flat plate is increased, SMD is always decreased.