• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.864-869
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• 2013

As the size of mechanical components decreases, capillary forces and surface tension become increasingly significant. A major problem in maintaining high reliability of these small components is that of large frictional forces due to capillary action and surface tension. Unlike the situation with macro-scale systems, liquid lubrication cannot be used to reduce friction of micro-scale components because of the excessive capillary and drag forces. In this work, the feasibility of using evaporation to coat a thin film of organic lubricant on a solid surface was investigated with the aim of reducing friction. Petroleum and silicone oils were used as lubricants to coat a silicon substrate. It was found that friction could be significantly reduced and, furthermore, that the effectiveness of this method was strongly dependent on the coating conditions.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 2000.06a
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• pp.127-142
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• 2000

The charged cluster model states that chemical vapor deposition (CVD) begins with gas phase nucleation of charged clusters followed by cluster deposition on a substrate surface to form a thin film. A two-chambered CVD system, separated by a 1-mm orifice, was used to study gold deposition by thermal evaporation in order to determine if the CCM applies in this case. At a filament temperature of 1523 and 1773 K, the presence of nano-meter sized gold clusters was found to be positive and the cluster size and size distribution increased with increasing temperature. Small clusters were found to be amorphous and they combined with clusters already deposited on a substrate surface to form larger amorphous clusters on the surface. This work revealed that gold thin films deposited on a mica surface are the result of the sticking of 4-10 nm clusters. The topography of these films was similar to those reported previously under similar conditions.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.110-119
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• 2005

The combustion characteristics of binary component single droplets hanging at the tip of a quartz fiber are studied experimentally at different environmental pressures and temperatures under normal gravity. Normal Heptane and Normal Hexadecane are selected as two fuels with high difference in boiling temperatures. A falling electrical furnace in a high pressure vessel has provided high temperature environment. Nitrogen and air have formed the environment to study evaporation and combustion, respectively. The initial diameter of droplet was ranging from 1.1 to 1.3 mm. The evaporation and combustion processes were recorded by a high speed digital camera. Some characteristics of droplet burning under different environment conditions and different droplet composition have been investigated. Microexplosion of droplet take places under atmospheric pressure. Bubble formation and its consequent result, incomplete droplet disintegration which presents in all binary compositions, do not appear at high pressure. The initiation of combustion, always takes place in the bottom of droplet due to buoyancy effect of relatively cold fuel vapor. Also, the burning of binary droplet produces soot when the pressure is high.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.41-44
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• 1995

The electrochromic WO$_3$ thin films were prepared by using an electron - beam evaporation technique. The influence of the electron - beam evaporation conditions. especially the vacuum pressure, and resistance of ITO substrate on the structural and electrochromic properties of the investigated film was presented. This films showed electrochromic behavior in an aqueous electrolyte of 1 M H$_2$SO$_4$. Among these WO$_3$ thin films, films prepared at a vacuum pressure of 10$^{-4}$ mbar were found to be most stable in terms of cycling durability. The chemical stability of film against dissolution in the aqueous solution was also shown to depend on the quantity of water in the film.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.36-43
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• 1999

Many of thermodynamic-based diesel combustion simulations incorporated a model of fuel spray which attempts to describe how the spray develops according to time. Because the spray geometry is an essential aspect of the fuel-air mixing process, it is necessary to be calculated quantitatively for the purpose of heat release and emission analysis. In this paper, we proposed the calculating method of non-evaporation spray behaviors by injection rate shapes under actual operating conditions of diesel engine. We confirmed the utility of this calculating model as the calculated results were compared with the measured results. This calculating program can be applied usefully to study on the diesel spray behavior.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.708-714
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• 2001

Although LP gas has lots of advantages, there has been limitation in application for automotive engine due to the several disadvantages, such as power decrease, complex fuel supply unit, and back fire etc. However LP gas direct injection engine has possibility to solve the problems above mentioned. LEM(Light Extinction Method) was employed for analysis of spacial and temporal distribution of LP gas which is directly injected into combustion chamber under various pressure and temperature conditions. The results from CVC(Constant Volume Chamber) were compared to those of RICEM(Rapid Induction, Compression and Expansion Machine) which simulate early- and late injection of direct injection engine. LPG fuel spray is affected by temperature and pressure in evaporation characteristics but it is more benefit to direct injection engine in every way such as, fuel distribution, evaporating speed and well wetting reduction.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.68-74
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• 2005

The objective of the present work is to examine the evaporation shape of deposited droplet on the hot surface. this paper performed the experiments as following conditions: (a) the surface temperature is within the range between $80^{\circ}C$ and $95^{\circ}C$ in the conduction and radiation, (b) droplet diameter is 3.0mm. The results are as follows; while droplet evaporates, droplet's radius is kept changelessly to $70\%$ evaporation time and droplet's shape is kept changelessly after. In case use Constant radius model, about $10\%$ is appearing high than value that time-averaged heat flux applies Inverse heat conduction.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.25-30
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• 2011

A fresh water generation system is designed for converting brackish water or seawater into fresh water. In this paper fresh water generation by distillation process that evaporates feed water and subsequently condenses vapor as evaporation product to get fresh water was studied and city water was employed as feed water. The system uses the ejector to create a vacuum, under which liquid can be evaporated at lower temperature than it at normal or atmospheric condition, hence less energy consumption. The effect of various operating conditions i.e. temperature of feed water and different orifice diameters were studied experimentally to investigate the characteristic of the system. It was found that these parameters have significant effect in the performance of fresh water generation system with low pressure evaporation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.620-628
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• 2008

Cadmium sulphide (CdS) thin film, which is used as a window layer of heterojunction solar cell, on the glass substrate was deposited by vacuum evaporation. Effects of deposition conditions such as the source and substrate temperature on electrical and optical properties of CdS films was investigated. As the source temperature was increased, the deposition rate of CdS films was increased. In addition, the optical transmittance and the electrical resistivity of CdS films were decreased as the source temperature was increased. This results were attributed to the increase of excess Cd amount in the film. The crystal structure of CdS films exhibited the hexagonal phase with preferential orientation of the (002) plane. As the substrate temperature was increased, the crystal structure of CdS films was improved and the resistivity of the films was increased due to the decrease of excess Cd in film.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.4
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• pp.498-505
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• 1986

In2O3: Sn(ITO) transparent conducting films were fabricated by the electron beam evaporation method. The dependence of their electrical and optical properties on deposition conditions were examined. The optimum evaporation conditions were such that the deposition rate was 5-10\ulcornersec, oxygen partial pressure was 4x10**_4 torr, substate temperatudre was above 300\ulcorner, and SnO2 doping rate was 10 mol%. The values of sheet resistance and transmittance of the films in visible region fabricated under these optimum conditins were 12\ulcorner/ and 87-99%, respecively. And the energy conversion efficiency of the SIS solar cell fabricated using ITO was 9.16%. It is shown that the transparent conducting films can be applied to the TV camear pick-up tube and solar cell.