• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.66-73
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• 2002

Fin effectiveness and efficiency of a thermally asymmetric triangular fin are represented as a function of the ratio of fin lower surface Biot number to upper surface Biot number and the non-dimensional fin length. For this analysis, two dimensional separation of variables method is used. When fin effectiveness is 2 and efficiency is 90%, the relationship between the non-dimensional fin length and the ratio of fin lower stir(ace Biot number to upper surface Biot number is shown. The relationship between the non-dimensional fin length and the upper surface Biot number for the same condition is also presented.

• The KSFM Journal of Fluid Machinery
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• v.11 no.6
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• pp.31-37
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• 2008

Film cooling effectiveness on the convergent or divergent channel was measured by pressure sensitive paint technique. The channel convergent or divergent angle was changed from $-5^{\circ}$ to $10^{\circ}$ and the tested blowing ratios were 0.5, 1 and 2. Results showed that the film cooling effectiveness on the convergent channel was not much affected by the convergent angle. With divergent film cooled surface, the film cooling effectiveness near the injection hole decreased as the divergent angle increases. However, the film cooling effectiveness at far downstream from the hole showed opposite trend. For the non-film cooled surface inclined case, the film cooling effectiveness was not much affected by the divergent angle.

• Journal of the Korean institute of surface engineering
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• v.39 no.5
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• pp.210-214
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• 2006

In order to enhance the electromagnetic shielding efficiency of commercialized cold-rolled steel sheets, we have prepared Ni deposited steel sheets by the electrodeposition method. Surface alloying with Ni and Fe was achieved on a steel sheet by diffusion annealing process. Shielding effectiveness measurement results showed that annealed Ni electrodeposited steel sheets enhanced the shielding efficiency up to about 3 dB in the frequency range of 20 to 200Hz, compared with that of non-deposited steel sheets.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.9-10
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• 2006

A numerical method for simulating tree surface flows including the surface tension is presented. Numerical scheme is based an a fractional-step method with a finite volume formulation and the interface between liquid and gas is tracked by Volume of Fluid (VOF) method. Piecewise Linear Interface Calculation (PLIC) method is used to reconstruct the interface and the surface tension is considered using a Continuum Surface Force (CSF) model. Several free surface flow phenomena were simulated to show its effectiveness to find such phenomena.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.53-58
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• 2008

Film cooling effectiveness on a flat plate was measured with pressure sensitive paint. The pressure sensitive paint(PSP) changes the intensity of its emissive light with pressure and the characteristic was used in film cooling effectiveness measurement. The film coolants were air and nitrogen, and by comparing the intensity of PSP coated surface with each coolant, the film cooling effectiveness was calculated. Three blowing ratio of 0.5, 1, and 2 were tested with two mainstream turbulence intensities. Results clearly showed the effect of blowing ratio and mainstream turbulence intensity. As the blowing ratio increases, the film cooling effectiveness was decreased near the film cooling holes. However, the film cooling effectiveness far downstream from the injection hole was higher for higher blowing ratio. As the mainstream turbulence intensity increased, the film cooling effectiveness was decreased at far downstream from the injection hole.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.05a
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• pp.33-33
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• 2003

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.579-588
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• 2003

Optimum fin effectiveness of geometrically and thermally asymmetric trapezoidal fins is represented as a function of the ratio of the fin bottom to top Biot numbers, the ratio of the fin tip to top Biot numbers and fin shape factor. Optimum fin effectiveness is taken as 98% of the maximum fin effectiveness by comparing the increasing rate of fin effectiveness with that of dimensionless fin length. For this analysis, two dimensional separation of variables method is used. Also, the value of the slope of upper surface of the fin and fin efficiency corresponding to optimum effectiveness are presented.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.183-186
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• 2009

The crystalline silicon solar cell was one of the first to be developed and it is still the most widely used type. The photovoltaic cells will exhibit long-term degradation if the temperature exceed a certain limit. The purpose of this study is to investigate the possible of improving the performance of a photovoltaic cooling system. According to the results of the experiment, the thermal degradation of 44.63degrees was observed by cooling on the surface of photovoltaic cells. It is a decrease of 22.215percent of generating power. It is shown that photovoltaic cooling system is effected on improving the effectiveness of a photovoltaic out of power.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1900-1906
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• 2000

In this study, the vibration screening effectiveness of barriers which can isolate structures from ground-transmitted vibration generated by harmonic forces is performed. For high frequencies, the vibration screening effectiveness of barriers is analyzed from field tests, and compared with the results from numerical analyses using a commercial program, ANSYS. Using these numerical analysis procedures, the effectiveness for vibration with various low frequencies is predicted. The frequency analysis tests of surface waves are performed in order to estimate the dynamic material properties of soil for 100 Hz, 150 Hz, 200 Hz, and 250 Hz. Three-dimensional solid elements are used in order to consider the diffraction of waves in all directions. Spring-damper combination elements are used in order to avoid the reflection of waves on the boundary. The results of numerical analysis agree with those of field tests. From the results of this numerical analyses, the reduction of vibration for low frequencies induced by the traffic loads can be predicted.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1185-1194
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• 2022

The maintenance of condenser main pipe is the key to achieve film-forming amine maintenance effectiveness. In this work, oxygen content, pH and temperature of the solution were controlled to simulate the condition of condenser main pipe, and magnetite coated carbon steel sample was prepared by pre-oxidization. CAM was used to characterize the hydrophobicity of film formed samples. Hydrophobic film was formed on pre-oxidized carbon steel samples when octadecylamine concentration reaches 20 mg/kg. SEM, EDS, EIS, and PD were used to characterize the influence of octadecylamine concentration on maintenance effectiveness. It was found that the maintenance effectiveness was enhanced and the corrosion rate was suppressed with the increase of octadecylamine concentration. FIB and TEM were used to detect the adsorbed octadecylamine film thickness founding that octadecylamine adsorbed onto the surface of pre-oxidized carbon steel by multi-layer adsorption mechanism.