• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.30-33
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• 2006

Onset voltage plays a crucial role in the design of a spray microthruster. This paper presents an analytical electrostatic model to predict the behavior of onset voltage in an array of emitters. The basic idea of this method is to superimpose the electric potentials obtained from each individual emitter in an array of emitters. The results show that if one emitter operates and the other neighboring emitters are dry, the potential required for cone-jet spraying generally increases as the emitter spacing decreases (due to electrical shielding). However at very close spacing the potential can decrease. If all emitters operate at the same time, the phenomenon that even at very close spacing the onset voltage required for cone-jet spraying increases merely as the emitter spacing decreases.

• 한국건축시공학회지
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• 제13권6호
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• pp.594-601
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• 2013

One of the important problems associated with building demolition is the dust generated during the work. The only way to reduce the demolition dust is to use a dust net during water spraying. However, it is difficult to supply the necessary amount of water to remove demolition dust, thus making it difficult to apply this method on a demolition site. This work attempted to find an alternative approach to dust removal by incorporating surfactant and high range AE water reducer in the water being sprayed. Through the experiment, it was found that the addition of surfactant did not contribute to the removal of demolition dust. However, the use of high range AE water reducer showed better performance than spraying plain water, indicating that some amount of demolition dust had been adsorbed on the high range AE water reducer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.168-173
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• 2000

Flame aerosol synthesis technology refers to the formation of fine particles from gases in flame and is widely used in practical materials processing. In this paper, an experimental investigation was performed on growth of the silica particles that were generated in $H_2/O_2$ Diffusion Flame by the direct injection or TEOS using Electro-spraying method. in this flame aerosol synthesis, four main parameters or nos interaction (flame temperature, residence time or particle in flame, TEOS flow rate, applied voltage) for particle generation and growth was investigated along the axial direction above the burner. A fairly monodisperse non-aggregated particles were successfully obtained.

• Journal of Ginseng Research
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• 제11권1호
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• pp.66-76
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• 1987

벼씨를 고려인삼차(영수삼차, 고려인삼제품(주)제품) 수용액(100배 희석)으로 28시간 불린 다음 파종하면 벼의 초기발육에 좋고 특히 파종직후 인삼차수용액(30배 희석)로 철포(10l/a)하면 그 효과가 더욱 좋았으며 병충해에 대한 내성이 증가하였다. 수확면으로 보면 무처리군에 비하며 벼씨만 인삼차수용액으로 처리한 것이 9.4% 증산, 인삼차수용액으로 처리한 것이 9.4% 증산, 인삼차수용액으로 처리한 벼씨를 파종한 직후 다시 진한 인삼차수용액을 철포한 것이 17.7% 증산의 성적을 보였다.

• 설비공학논문집
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• 제14권10호
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• pp.786-791
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• 2002

An experimental study on the behavior of the water hold-up by spraying of a fin-and-tube heat exchanger with regard to the surface characteristics, i.e., contact angles, was conducted. The dynamic contact angles (DCA) were measured, and water hold-up by spraying (WHS) was conducted in the experiment. It is found that heat exchanger surface characteristics, spray pressure, spray water temperature and heat exchanger surface temperature play an important role in WHS. In order to evaluate relationship between WHS and surface characteristics, test conditions are determined through a contour analysis. A correlation was proposed to predict WHS as a function of DCA. With its test efficiency and consuming time, the prediction method can be used to evaluate WHS performance.

• Corrosion Science and Technology
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• 제4권1호
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• pp.33-38
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• 2005

Some feasibility studies are conducted to produce an advanced ceramic coating, which reveals superior chemical and mechanical strength, on metal base structure used in chemical plant. This advanced coating on metallic frame can replace ceramic delivery pipe and reaction chamber used in chemical plant, which are operated in hi-temperature and corrosive/erosive environment. An dual spraying is adopted to reduce the residual stress in order to increase the coating thickness and the residual stress is estimated by in-situ manner. Then new methodology is tried to form special coating of yttrium aluminum garnet(YAG), which reveals hi-strength and low-creep rates at hi-temperature, superior anti-corrosion property, hi-stability against Alkali-Vapor corrosion, and so on, on iron base structure. To verify the formation of YAG during thermal spraying, XRD(X ray diffraction) technique was used.

• Journal of Welding and Joining
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• 제18권5호
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• pp.112-116
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• 2000

The development of new spraying processes has increased the demand for high quality protective coatings. Many thermal spraying processes have been developed to obtain coatings for a wide spectrum of materials and substrates. The plasma spray process was used to deposit coatings of WC-12%Co powders on mild steel substrate, and the characteristics of as-sprayed and vacuum heat treated coatings have been investigated. The variations of microhardness and bond strength in WC-12%Co coatings after heat treatment under vacuum circumstance have been investigated. The effects of phases and morphologies of WC-12%Co coatings have been investigated by utilizing X-ray diffraction and scanning electron microscopy, respectively. The microhardness and bond strength of the coatings were increased with increasing the temperature in the temperature range of $700^{circ}C~1000^{\circ}C$. The bond strength was obtained 49 MPa after vacuum heat treatment at $1000^{\circ}C$.

• 한국분말재료학회지
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• 제15권6호
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• pp.477-481
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• 2008

Formation and characteristics of spraying powder for BSCCO High-Tc superconductor prepared by plasma spray coating were investigated. The addition of 3% of binder gives the best flowability of the powder. Ball milling for 30h and 35h gives the best flowability of powder in the case of 2001 and 0212, respectively. The withdraw ratio increases upon binder addition from 12 to 27% in the case of 2001 and from 18 to 31% in the case of 0212 for sieving powder of $30-90{\mu}m$ in size. The built-up efficiency for $100{\mu}m$ thickness of spray coating is increased more than 30% by binder addition. The microstructure of the spray coated layers was investigated by XRD and EDS analysis.

• 한국세라믹학회지
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• 제36권4호
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• pp.444-450
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• 1999

Hydroxyapatite(HA) was spray-coated to alloy substrate(Ti-6Al-4V) using plasma-spray process for bioceramic application The coating morphology composition and crystallinity were influenced by following process parameters ; stand-off distance spray power level and auxiliary gas pressure. These parameters have been systematically varied in the present study to evaluate their relative influence on the coating qual-ity and to seek an optimum spraying condition. Amorphicity and decomposition of HA increased with stand-off distance and the imperfect coating layer was obtained at the short stant-off distance (55mm). The cry-stallinity of HA coating decreased with spray power level and auxiliary gas pressure but the bond strength between the HA coated layer and Ti alloy substrate increased with the spray power level.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.77-82
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• 2008

Rubbing-roller is used for manufacturing liquid crystal display, and static displacement of the rubbing-roller becomes bigger as length of the rubbing roller made of aluminum is getting longer. Therefore, material of the rubbing-roller is changed from aluminum to CFRP(Carbon Fiber Reinforced plastic). Recently thermal spraying is applied to manufacturing process of long rubbing-roller. The thermal spraying has disadvantages such as increment of manufacturing time and fraction defective caused by density of stainless steel particle. In this study, fitting process by drawing was suggested and FEM analysis with Tsai-Wu failure theory and fitting experiments are carried out to find adequate shrink allowance. The suggested shrink allowance gives proper adhesive force, and CFRP failure is not occurred. Furthermore, the fitting process is applied to long rubbing-roller and availability of the fitting process is studied by measurement of roundness, straightness and shear strength.