• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.641-642
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• 2006

The modelling of some different types of switchgears has been reported in the previous papers. This paper consists of two parts. The first part concerns the modelling and simulation of switching arcs with an auto-expansion circuit breaker as an example. The second part focuses on the simulation of the PTFE nozzle ablation effect with three different nozzle shapes. For circuit breakers, the modelling of moving contact and the choice of time steps are discussed before typical results are given and compared with available test result.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.62-66
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• 2015

The starting processes of the Ludwieg tube hypersonic quiet tunnel plays very important role in the achievement of the quiet flow in the test section, which could affect the confidence coefficient of the data in the hypersonic transition experimental investigations. Thus, numerical analysis on that processes could help to understanding the running mode of the Ludwieg tube quiet tunnel and the propagation principle of the expansion wave series. To verify our computational method, the same parameter of the BAM6QT (the Boeing/AFOSR Mach-6 quiet tunnel at Purdue University) is used to compute, and it is agrees with our computational results.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1459-1460
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• 2006

A new gas jet Z-pinch EUV light source having double gas jet electrodes has been developed. It has two nozzles and two diffusers. The EUV beam is collected from the side of pinch plasma, generated in between the inner nozzle and corresponding diffuser. A cylindrical shell of He gas curtain produced by the outer nozzle is specially designed for shielding the debris and suppressing the inner gas expansion. We have succeeded in generating EUV energy of 1.22 mJ/sr/2%BW/pulse at 13.5nm. The estimated dimension of EUV source is to be FWHM diameter of 0.07 mm and length of 0.34 mm, and FW 1/e2 diameter of 0.15 mm and length of 1.2 mm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.973-978
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• 2007

In this paper, we make a study of a thermal deformation by FEM and test to define the deformation mode of the Vacuum-Cleaner's Nozzle-Cover. In FEM analysis, 3 different conditions were considered separately, such as (1) Compressive force by Belt tension, (2) Friction heat between Belt and Shaft and (3) Compressive force combined with heat. Throughout FEM analysis it was found that the deformation was caused by heat and it was proved through a simulation test with a real product.

• Clean Technology
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• v.26 no.1
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• pp.1-6
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• 2020

Rapid expansion of supercritical solution (RESS) process was used to make molsidomine (MOL) loaded peracetyl-β-cyclodextrin (PAc-β-CD) nanoparticles, which were collected into the air. The effect of the concentration of the drug PAc-β-CD (0.5 and 1 wt%), extraction temperature (45 ~ 60 ℃), nozzle length (5 ~ 20 mm) and internal diameter (ID) (50 ~ 150 μm) of a capillary, and spray distance on the particle size and morphology of the resulting particles were investigated. The interaction of a drug and PAc-β-CD was confirmed by ¹H-NMR spectroscopy while the particle size was measured by means of a scanning electron microscope. It was found that increasing the temperature from 45 ℃ to 60 ℃ and decreasing the nozzle diameter from 150 μm to 50 μm had an increasing effect on the average particle size, while increasing the spray distance led to a decrease in the average particle size at a constant pressure of 34.5 MPa and temperature of 45 ℃. With 0.5 wt% of PAc-β-CD, the capillary nozzle of short length (5 mm) and small ID (50 μm) gave the smallest size (165 nm). The obtained nanoparticles showed increased dispersity and solubility in oil. The oil suspension of the inclusion complex showed increased sustainability, which can increase the in-vitro controlled release time of the drug.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.428-432
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• 2010

A study on the forming characteristics of outer shell structure for thrust chamber nozzle extension has been performed. In order to identify anisotropy of cold rolled sheet metal, three types of tensile specimens according to the direction to the sheet rolling axis were prepared and tested, and Landford's values were obtained using the results and applied to structural analysis. Forming characteristics of the outer shell structure of the nozzle extension are investigated through manufacturing and forming of the full scale outer shell structures, and strain values obtained by the forming processes are compared to the numerical analysis results. The results obtained by this study will be utilized to design forming tools and processes for manufacturing other outer shell structures which have a bigger expansion area ratio.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.1-9
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• 2022

A design factor analysis was conducted to reduce the thrust reduction in the off-design, due to the driving of the aerospike pintle nozzle. The close (NPR 100) as well as the open (NPR 11) stroke were fixed, as under-expansion conditions. The pintle contour, pintle head radius (R), cowl angle (θ), and cowl exit length (L) were selected as design factors. The change in thrust was analyzed, using a verified numerical analysis technique. First, the pintle head radius and the length of the cowl exit had little influence on the thrust. The cowl angle changed the mass flow rate by affecting the effective nozzle throat area, and created a reverse pressure gradient at the cowl exit. As a result of applying the dual aerospike contour, it was confirmed that the thrust in the design-off increased by approximately 1.2%, compared to the reference case and by approximately 3.4% compared to the worst case.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.741-745
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• 2011

Well-resolved vibronic emission spectra were recorded in the visible region from the corona discharge of precursor alkylbenzenes in a technique of corona excited supersonic expansion using a pinhole-type glass nozzle. From the observed spectra, we found the evidence of the presence of benzyl-type radicals generated by dissociation of C-C or C-H bonds of alkyl group. After identification of benzyl-type radicals formed in the corona discharge, we suggest that energy densities in alkyl chain play a crucial role in determining the bond dissociation during corona excitation.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.1
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• pp.53-62
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• 1987

The Performance of Pre-combustion Chamber Diesel Engine mainly depends upon the compression, combustion and Expansion Processes. The analysis of varying tendency of the work factors for crank angles during these processes, which are consisted of 5 items such as exothermic energy, flow work, work in nozzle part, kinetic energy and cooling energy, are considered important as basic elements for effective combustion and performance improvement. In this paper, varying tendencies of the theoretical factors are investigated with pressure data through experiments. By the results, the trends of work factors are presented as basic data for comparing the influencing effects on work.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1359-1363
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• 1998

The p-fluorobenzyl radical was generated from the p-fluorotoluene and vibronically excited in a corona excited supersonic expansion with inert buffer gases. The vibronic emission spectra of the jet cooled p-fluorobenzyl radical in the D1 → D0 transition have been observed in the visible region. The spectra exhibit several low frequency sequence bands in the vicinity of the every strong vibronic band. The characteristics of the sequence bands have been examined by varying the experimental conditions such as carrier gas and nozzle size to identify the origin of the transition in the spectra.