• Journal of the Korean Wood Science and Technology
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• v.17 no.1
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• pp.55-68
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• 1989

This experiment was carried out to investigate the crack of coated Nitrocellulose Lacquer on flatand edge-grained boards of Quercus acutissima, ring-porous wood, and Betula platyphylla var. japonica, diffuse-porous wood, by variations of moisture contents at 7, 13 and 21%. Cold check system was used as an accelerating method for crack development, in which one cycle of the system consisted of 10 replications of each unit cycle, $60^{\circ}C$ for 4hr followdd by $-20^{\circ}C$ for 4hr. The analysis of Nitrocellulose Lacquer characteristics was made by means of water permeation measurement, F.T.I.R. spectroscopy, N.M.R. spectroscopy, gel permeation chromatography, gas chromatography, and D.S.C. The results obtained were as follows: 1. The number of cracks increased with the increasing moisture content of board. 2. The crack of coated film on flat-grained board was fewer in number than on edge-grained board. 3. The crack occurred in Quercus acutissima was more numerous on edge-grained board but less frequent on flat-grained board compared with that in Betula platyphylla var. japonica, respectively. 4. The cold crack vertically developed to the grain both in Quercus acutissima and Betula platyphylla var. japonica. 5. Water permeability in intermediate coated film was lower than in under and top coated film, but the difference was not confirmed between under and top coated film.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.27-33
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• 2014

Electrical resistivity of concrete can be measured in a more rapid and simple way for estimating durability of the concrete, however, carbonation causes a result of misleading for durability testing because carbonation leads to a significant reduction in the permeability and porosity of concrete. The purpose of this study is to estimate and quantify the effect of carbonation of concrete on a surface electrical resistivity measurement. Samples of three mixes with difference w/c were prepared and exposed in a carbonation chamber for 330 days. The results show that carbonation leads high electrical resistivity. The increase is substantial and has been shown to proportional to the extent of the carbonation by some of extent. The relationship between electrical resistivity and carbonation depth is taken in the study. Resistivity ratio of carbonated concrete to air concrete decreased significantly from the specific carbonation depth, however, resistivity ratio of carbonated concrete to air concrete had a linear relation with carbonation depth. From the relationship between electrical resistivity and carbonation depth, it is expected that the result should be subsequently used as a calibration curve for estimating carbonated concrete to overcome the interruption effect of carbonation on regular measurements of the electrical resistivity.

• Journal of Fashion Business
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• v.12 no.3
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• pp.116-135
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• 2008

To investigate the actual distribution condition and clothing construction factors of the working clothes supplied to the Changwon national industrial complex, 5 major companies in machinery, automotive, industrial engineering, shipbuilding and rolling stock in the industrial complex located in Gyeongsangnam-Do were selected. The questionnaire designed for the research consisted of working clothes distribution policies in manufacturing industry and the actual conditions of the design facts, repair and maintenance of the working clothes, etc. The analysis of the clothing construction factors of the working clothes provided by 5 respondent companies were conducted in parallel. The results derived from the study were as follows: The basic types of working clothes were the blouson jacket and straight pants; safety equipments for manufacture were safety helmets, gloves, snickers, goggles, masks, ear caps, wristlets, leggings, apron, etc. The size-charts adopted by the participant companies were the small-medium-large and cm/inch measurement size systems. To solve wearer's dissatisfaction with the garment fit, certain clothing construction factors were used, e.g. strap bands and the elastic band on a waist band. The types of fabrics used for the working clothes were mainly polyester/cotton and polyester/rayon blended ones. Moreover, to provide with more air permeability to wearers, the warp knit material was used to construct the lining and the armpit or back bodice slits. Lock, two-thread chain, safety, overedge stitches were applied with flat, lap felled, French, superimposed, lapped, bound and edge finishing seams to construct the working clothes selected.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.249-255
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• 2015

Functional nanochannels were fabricated in order to control selective ion transportation with high permeability and low energy consumption. In this research, nanochannel platform fabrication process and surface functionalization process were developed. In addition, selective ion transportation and concentration measurement system was also set-up. By using fabricated multilayer metal membrane with electrical bias, 95% of ion ($Cl^-$) was blocked. This developed process is new-conceptional membrane fabrication technology and is expected to be applied to next-generation water purification/desalination, portable artifical kidney, and artificial sense organ.

• Textile Coloration and Finishing
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• v.32 no.3
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• pp.176-183
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• 2020

In order to study wearable air cushion materials capable of responding to massive impact in high-altitude fall situation, high tenacity woven fabrics were bonded by heat only depending on various type of thermoplastic films and then mechanical properties were measured. Tensile strength, elongation, and 100% modulus measurement results for 4 types of films show that TPU-2 has higher impact resistance and easier expansion than PET-1. After thermal bonding, the combination with the highest tensile strength was a material with a TPU-2 film for nylon and a PET-2 film for PET, so there was a difference by type of fabric. The tear strength of the bonded materials were increased compared to the fabric alone, which shows that durability against damage such as tearing can be obtained through film adhesion. All of the peel strengths exceeded the values required by automobile airbags by about 5 times, and the TPU-2 bonded fabric showed the highest value. The air permeability was 0 L/dm2 /min. For both the film and the bonded material, which means tightness between the fabric and the film through thermal bonding. It is expected to be applied as a wearable air cushion material by achieving a level of mechanical properties similar to or superior to that of automobile airbags through the method of bonding film and fabric by thermal bonding.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1367-1374
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• 2008

A new high-gain Fabry-$P{\acute{e}}rot$ cavity antenna for wireless broadband internet(Wibro) base station antennas, which is covered with metamaterial superstrate presenting simultaneous negative values of permittivity and permeability, is proposed. To facilitate the fabrication process using the printed circuit board(PCB) technology of today, a new planar-type metamaterial superstrate is designed, which shows negative and low positive values of a refractive index near the Wibro service frequency band. And the principle of antenna gain enhancement is analyzed from the two different view points of effectively low refractive index and of the Fabry-$P{\acute{e}}rot$ resonance condition. Single square patch antenna is used as a feeder. The separation distance is determined by considering the reflection phases of the metamaterial superstrate and the substrate satisfying Fabry-$P{\acute{e}}rot$ resonance condition, respectively. Comparison between the prediction and the measurement shows good agreement, which verifies the validity of our design approach.

• Journal of the Korean Geotechnical Society
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• v.32 no.3
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• pp.29-37
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• 2016

SSG (self-healing smart grouting) method, which is developed recently, has the characteristics such as an improvement of durability and waterproofing, prevention of leaching and pollution. In this study, we performed several tests such as gel-time measurement, uniaxial compression test, permeability test, fish poison test and chemical resistance test to compare the engineering properties of SSG with the other chemical grouting method (LW, SGR). As results of tests, the SSG method has low possibility of groundwater and ground pollution caused by leaching, furthermore, it has advantages like long/short term waterproofing, strength and durability. Therefore the SSG method can be applicable in the fields as an alternative of existing chemical grouting methods with problems.

• Polymer(Korea)
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• v.35 no.4
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• pp.296-301
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• 2011

This study focuses on the investigation of the impregnation of poly (vinyl alcohol) (PVA) crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) to porous polyethylene membrane for the fuel cell application. The membranes were characterized by the measurements of the water content, contact angle, FTIR spectra, thermal gravimetric analysis, ion exchange capacity, proton conductivity, methanol permeability and elastic modulus. The existence of hydrophilic moieties in the impregnated membranes was confirmed by contact angle and FTIR measurements. The impregnated PVA/PSSAMA(90:10) membrane exhibited a higher ion exchange capacity (1.2 meq./g dry membrane) than Nafion membrane (0.91 meq./g dry membrane). Through the elastic modulus measurement, the dimensional stability of the resulting membranes was expected to increase higher than the polyethylene membranes. The methanol crossover and water content decreased even if the PSSA-MA content increased due to the reduction of the free volume.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.245-251
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• 2018

Recently, as the importance of structural maintenance has been increased, studies on self - healing concrete technology are being actively carried out. On the other hand, test for evaluating the self-healing performance is not standardized yet. Although visual test is used as a basic method for measuring crack widths, it is difficult to observe the crack width inside the specimen, and there is a disadvantage that only the local measurement of the surface can be measured due to the inhomogeneous cracking characteristics. Although permeability test has been widely used as an indirect method for measuring crack width, there is a problem due to the viscosity of water, and also a possibility that the internal material of the specimen may be eluted during the test. In this study, we propose a crack width evaluation method using gas diffusion characteristics. Idealized straight cracks were fabricated by acrylic and the diffusion coefficients of specimens were analyzed with respect to crack width and thickness. The experimental results show that the crack width and the diffusion coefficient are in a linear relationship and that the thickness and diffusion coefficient are inversely related.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.1
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• pp.30-38
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• 2009

In recent years, there's been strong demand for coastal structures that have a permeability that serves water affinity and disaster prevention from wave attack. The aim of this study is to examine the wave transformation, including wave run-up that propagates over the coastal structures with a steep slope. A numerical model based on the nonlinear shallow water equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable underlayer and laboratory measurements was carried out in terms of the free surface elevations and fluid particle velocities for the cases of regular and irregular waves over 1:5 impermeable and permeable slopes. The numerical results were used to evaluate the application and limitations of the PBREAK numerical model. The numerical model could predict the cross-shore variation of the wave profile reasonably, but showed less accurate results in the breaking zone that the mass and momentum influx is exchanged the most. Except near the wave crest, the computed depth averaged velocities could represent the measured profile below the trough level fairly well.