• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.205-213
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• 2016

Heat loss and fin efficiency of symmetric and asymmetric trapezoidal fins with variable slope of fin's top surface are obtained by using a two-dimensional analytic method. Shapes of symmetric and asymmetric fins are changed from rectangular through trapezoidal to triangular by adjusting the fin shape factor. The ratio of symmetric trapezoidal fin length to asymmetric trapezoidal fin length is presented as a function of fin base height and convection characteristic number. The ratio of symmetric trapezoidal fin efficiency to asymmetric trapezoidal fin efficiency is presented as a function of the fin base height and fin shape factor. One of results shows that asymmetric trapezoidal fin length is shorter than symmetric trapezoidal fin length (i.e., asymmetric trapezoidal fin volume is smaller than symmetric trapezoidal fin volume) for the same heat loss when the fin base height and fin shape factor are the same.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.6
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• pp.417-426
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• 2006

A Digital X-ray imaging system using Compton backscattering has been developed to obtain a cross-sectional profile and mass loss of corroded lap-splices of aging aircraft from density variation. A slit-type camera was designed to focus on a small scattering volume inside the material, from which the backscattered photons are collected by a collimated scintillator detector for interpretation of material characteristics. The cross section of the lap-joint is scanned by moving the scattering volume through the thickness direction of the specimen. The mass loss of each layer has been estimated from a Compton backscatter A-scan to obtain the thickness of each layer including the aluminum sheet, the corrosion layer and the sealant. Quantitative information such as location and width of planar corrosion in the lap splices of fuselages is obtained by deconvolution using a nonlinear least-square error minimization method(BFGS method): A simple reconstruction model is also introduced to overcome distortion of the Compton backscatter data due to attenuation effects attributed to beam hardening and quantum noise.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.471-478
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• 2000

Ground movements are inevitably caused by tunnel construction in soft ground. In the design and construction of tunnels in urban areas, the potential effects of buried pipelines by ground movements are one of the important design cosiderations. Generally, the most common modes of failure of buried pipelines due to ground movements are tensile fracture of main pipelines, rotation angle and pull-out displacement at joints. In the parametric study, a wide range of conditions were considered, including tunnel diameter(D), tunnel depth(Z$\sub$0/), volume loss(V$\sub$ι/) and inflection point(i). Based on this results, design charts, which are applicable to assess potential damage of buried pipelines associated ground movements due to tunnelling, are developed.

• Carbon letters
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• v.10 no.2
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• pp.97-100
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• 2009

In this work, effects of carbon matrix on sliding friction and wear behavior of four kinds of C/C have been investigated against 40 Cr steel ring mate. Composite A with rough lamination carbon matrix (RL) shows the highest volume loss and coefficient of friction, while composite D with smooth lamination/resin carbon matrix (SL/RC) shows the lowest volume loss. The worn surface of composite A appears smooth, whereas that of composite C with smooth lamination carbon (SL) appears rough. The worn surface of composite D appears smooth under low load but rough under high load. Atomic force microscope images show that the size of wear particles on the worn surface is also dependent on the carbon matrix.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1406-1407
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• 2008

In this paper, a micro balanced filter in magnetically coupled LC resonators is proposed, designed, simulated by using FR-4 PCB substrate for low cost, small volume IEEE 802. 11a wireless LAN application. Two pair of coupled LC resonators using magnetic coupling of embedded inductors are applied to obtain bandpass transmission response and improve their phase and magnitude imbalance characteristics. In addition, high dielectric composite film is applied to fabricate the high Q MIM capacitors with small size and high capacitance density. It has an insertion loss of 1.4 dB, a return loss of 10 dB, a phase imbalance of 0.25 degree, and magnitude imbalance of 0.17 dB at frequency bandwidth of 200 MHz ranged from 5.15 GHz to 5.35 GHz, respectively. The proposed balanced filter has a small volume of $1.1mm{\times}1.3mm{\times}0.6mm$ (height).

• Journal of the Korean Society of Safety
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• v.15 no.4
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• pp.41-46
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• 2000

Silicone rubbers are elastomeric materials and organic copolymers, of which backbone is siloxane with high bonding strength. Silicone rubbers have been used as an power insulator because they are well weather proof, ozone proof and have excellent electric characteristics, thermal stability, cold resistance and low surface energy. Especially, it is known that they have very excellent characteristics at 200[$^{\circ}C$]. For this study, we made silicone rubbers as specimens and measured volume resistivity due to applied voltage and a variation of temperature 25[$^{\circ}C$] to 180[$^{\circ}C$]. Also we measured dielectric loss tangent due to applied voltage at temperature range 25[$^{\circ}C$] to 180[$^{\circ}C$] and frequency range 20[Hz] to 1${\times}10^6$[Hz].

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.95-102
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• 2006

This study analyzes and optimizes a design for a trapezoidal profile straight fin using one-dimensional analytical method. The heat transfer, fin length and fin height are optimized as a function of fin volume, fin shape factor and fin base length. In this optimization, convection characteristic number over fin surface and that of fluid inside fin wall are considered. One of the results shows that the maximum heat loss increases as fin volume increases and both fin shape factor and fin base length decrease.

• Journal of the Korean Society of Combustion
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• v.5 no.2
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• pp.63-68
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• 2000

Combustion phenomenon in scale-downed combustor is investigated. As the combustor scale decreases surface to volume ratio increases and chamber size approaches quenching distance. As the combustor scales down surface to volume ratio increases resulting increased heat loss. And this heat loss can affect quenching and instability of the flame. To investigate this effect plastic mini combustor is made. Stoichiometricaly premixed Hydrogen / air gas is used as fuel. Initial chamber pressure and chamber size are varied and the effects are evaluated. Peak pressure decreased with the decrease in chamber height. As initial chamber pressure decreases peak pressure decreases and this change is more important than scale down effect till the chamber height of 1mm. With this result and further information following the experiments design parameter for micro engine can be established.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.2
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• pp.239-245
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• 2012

Mulberry fruit powder was substituted for wheat flour in pound cake recipes in amounts of 0%(control), 5%, 10%, 15%, and 20%. We measured the specific gravity of the dough, specific loaf volume, dough yield, baking loss, moisture content, pH, color, identified the texture, and conducted a sensory evaluation for each pound cake. Moisture content increased according to the amount of mulberry fruit powder, but specific gravity, dough yield, and pH decreased. Specific loaf volume and baking loss increased as the amount of mulberry fruit powder increased, but not considerably. The chromatic 'L' and 'b' values were reduced as more mulberry fruit powder was added to more pound cake, While the chromatic 'a' value increased. Texture hardness, springiness, gumminess and chewiness decreased as the pound cake contained more mulberry fruit powder. Cohesiveness did not show any considerable differences beteeen the cakes. A sensory evaluation showed a high preference for the pound cake made with 10% mulberry fruit powder.

• Journal of the Korean institute of surface engineering
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• v.27 no.1
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• pp.36-44
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• 1994

The TiN films were deposited on the stainless substrates using arc vapor ion deposition process to in-vestigated the wear resistance. Pin-on-disc tests were performed to measure the volume wear loss of TiN films. The substrate bias voltages and nitrogen flow rates were selected as the deposition parameters of TiN films. It was found that the wear resistance of TiN films was enhanced with increasing bias voltages(0~-300 V) and nitrogen flow rates(220~380 SCCM). The volume wear loss TiN films were about 9.5~2.1$\times$$10^{-3}mm^3$ and 3.5~2.2$\times$$10^{-3}mm^3$ with bias voltages and nitrogen flow rates, respectively.