• Journal of Conservation Science
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• v.30 no.3
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• pp.287-298
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• 2014

This study investigates the material properties of the traditional bricks used in the royal tomb of King Muryeong. Compressive strengths, thermal conductivities, absorptance and the rate of residual moisture are measured by non-destructive experiments. Compressive strength of the traditional bricks is estimated by using the ultrasonic wave velocity and the absorptance. Based on the experimental results, the predicted compressive strengths using the ultrasonic wave velocity are unsuitable for the traditional bricks due to the rough surface and thickness variation of the specimens. The strengths using the absorptance are more suitable than those using the velocity because the predicted average strengths (28.69 MPa ~ 33.19 MPa) are close to building materials like normal strength concrete. In addition, the methods using the absorptance are not influenced by surface and thickness conditions of the specimens. The average thermal conductivities of the bricks measured by using Mathis TCi are close to those of soils (1.58 W/mK). The absorptance and the rate of residual moisture of the bricks are 1.6 % ~ 15 %, 0 % ~ 0.7 %, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.87-88
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• 2011

High absorptance of lightweight aggregate make a hard product, work, quality management ect. for making low absorptance property, lightweight aggregate is coated by an organic matter and that way remarkably showed to decrease the absorptance by pre-study. but first, we would need a check to fit into the concrete which both fresh concrete and hardened concrete. In this study, mechanical property change of coated lightweight aggregate concrete was analysed by compared experiment with coated lightweight aggregate concrete and non-coated aggregate concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.13-16
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• 2008

This paper is to present the performance data for improved direct setting method using tile bond for application of porcelain tile under 1 percent absorptance. For this purpose, improved direct setting method type 1 & 2(tile bond curing time 0, 24H) were compared with the conventional setting methods(including direct setting method and improved pressure setting method) in the sight of the adhesive stability of porcelain tile. It tested for tiles after 14, 28days under standard condition and severe conditions. The severe conditions were water immersion, heat ageing(70℃) and freeze-thaw cycle. On the basis of test results, the adhesive strength of direct setting method was lowest for the conventional setting methods. But improved direct setting method using tile bonds(A, B) came close to the result of improved pressure setting method using tile bonds.

• KIEAE Journal
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• v.6 no.4
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• pp.33-39
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• 2006

This study aims to investigate the method to reduce the surface temperature caused by insolation. To achieve this goal, surface temperature of building is measured and the effects of exterior material's color and brilliance were checked with infrared imaging. And also, exterior material's absorptances due to outdoor surface heat transfer coefficients were measured. After surface temperature measurement of 37 specimen of 5 categories, the temperature is the highest on wood($53.62^{\circ}C$) and panel($52.05^{\circ}C$). Dryvit, stone, brick is the rating of order. For exterior material's absorptances, panel(0.883) and wood(0.868) were high and Dryvit, stone, brick follows wood and panel.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1257-1264
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• 2005

An inverse problem to determine two-dimensional total heat exchange factor is studied for the prediction of the slab temperature in the reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. This inverse analysis employs the conjugate gradient method. The overall heat absorptances for 12-zones of the cross-section of the slab are estimated. The estimated temperatures at measurement locations are in good agreements with the measured temperatures.

• Current Optics and Photonics
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• v.5 no.4
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• pp.375-383
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• 2021

We present a simulation method to design antireflection coating (ARCs) for fiber-coupled superconducting nanowire single-photon detectors. Using a finite-element method, the absorptance of the nanowire is calculated for a defined unit-cell structure consisting of a fiber, ARC layer, nanowire absorber, distributed Bragg reflector (DBR) mirror, and air gap. We develop a method to evaluate the uncertainty in absorptance due to the uncontrollable parameter of air-gap distance. The validity of the simulation method is tested by comparison to an experimental realization for a case of single-layer ARC, which results in good agreement. We show finally a double-layer ARC design optimized for a system detection efficiency of higher than 95%, with a reduced uncertainty due to the air-gap distance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.589-593
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• 2014

AlNO multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. $Al_2O_3$/AlNO(LMVF)/AlNO(HMVF)/Al/substrate of 4 multi-layer has been prepared in an Ar and ($N_2+O_2$) gas mixture, and $Al_2O_3$ of top layer is anti-reflection layer on double AlNO(LMVF)/AlNO(HMVF) layers and Al metal of infrared reflection layer. In this study, the roughness and surface properties of AlNO thin films were estimated by field emission scanning electron microscopy(FE-SEM). The grain size of AlNO thin films increased with increasing sputtering power. The composition of thin films has been systematically investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The absorptance of AlNO films shows the increasing trend with swelling ($N_2+O_2$) gas mixture in HMVF and LMVF deposition. The excellent optical performance showed above 98% of absorptance in visible wavelength region.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1105-1111
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• 2011

The objective of this study is to investigate the influence of surface roughness on the morphology of aluminum 6061-T6 alloy after irradiation with a Nd:YAG pulsed laser. The test specimen was prepared by a polishing process using a diamond paste ($1{\mu}m$) and emery polishing papers (#100, #220, #600, #2400) to obtain different initial surface roughness. After irradiation with ten pulsed-laser shots, the surface morphology was examined by using scanning electron microscopy (SEM), optical microscopy (OM), and atomic force microscopy (AFM). The diameter of the melted zone increased with the surface roughness because the multiple reflections and absorption of the laser beam occurred on the surface because of the surface roughness, so that the absorptance of the laser beam changed. This result was verified using the relative absorptance calculated from the diameter of the melted zone with the surface roughness and the diameter increased with the average surface roughness.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.27-35
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• 2013

One of the most important factors that have a large influence on performance of the solar water heater system is performance of the solar collector, more detailedly, coating technology on the surface of the solar collector, which can provide high solar absorptance and low emittance. The core of the coating technology is to coat solar selective surfaces. In this study, various performance experiments are carried out using $Cr_2(SO_4)_3{\cdot}15H_2O$ coating technology. Here, IGBT(Insulated Gate Bipolar Transistor) of 5000A-15V was used as the surface processing rectifier which can stably output power and also can control voltage and current. The plating solution mainly contains black chrome$^{+3}$ concentration, H-y Conductivity, N-u Complex, NF Additive and NC-2 Wetter. Before applying the black chrome coating on the copper plate, optimal conditions are provided by using various preprocessing methods such as removal of fat, activation, electrolytic polishing, nickel strike, copper sulfate plating and bright neckel plating, and then the automatic continuous coating experiment are performed according to plating time and cathode current density. In the experiment, after the removal of fat, chemical polishing, nickel strike and activation processes as the preprocessing methods, the black chrome coating was performed in a plate solution temperature of $28^{\circ}C$ and a cathode current density of $18A/cm^2$ for 90 seconds. The thickness of chrome and nickel on the coated plate is $0.389{\mu}m$, $159{\mu}m$ respectively. As a result of the coating experiment, it showed the most excellent performance having a high solar absorptance of 98% and a low emittance of $5{\pm}1%$ when the black chrome surface had a thickness of $0.398{\mu}m$.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.55-59
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• 2022

In this paper, we compared the electric field and absorptance of nano particles in nanostructures by amplifying the electric field around the nanoparticles through plasmon resonance and comparing the structure that can increase the absorptance with the nanostructure by using the Finite Different Time Domain (FDTD) simulation. In addition, the width of the nanostructure was adjusted to 240 nm ~ 300 nm, and the light absorptance rate was higher as the gap between the particles was short. In addition, a study was conducted on the formation of nanoparticles and nanostructures on the surface through UV imprint. In order to form particles in the structure, the nano particles were first arranged in the mold used for the fabrication of the structure using spray coating, and then fabricated through UV imprinting. The nanostructure and particles were formed together by scanning electron microscopy.