• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.408-417
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• 1995

A study on the surface roughness variation of work roll and strip at the temper rolling was performed. The results were obtained with changes according to the surface roughness of work roll and method to make the peak count on the roll in the temper rolling, and factors to affect to the work roll surface in actual rolling machine (ie. Temper mill). The results suggests that the electro-discharge textured roll has mere uniform roughness distribution than shot blasted roll and its life time is two times longer than shot blasted because it has more sine wave roughness, and it is possible to control the Rmax. In shot blasting method, Surface roughness is related to the impeller speed, But it can't control the peak count.

• Journal of Korean Library and Information Science Society
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• v.46 no.2
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• pp.317-336
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• 2015

This paper provides a brief overview of bibliographic relationships, a analysis of bibliographic relationships' characteristics of 2,940 bibliographic records on the Five Classics and Four Books taken from Korean National Bibliography, and a methodology for applying the FRBR model based on analysis of the samples. As results of analysis, the work type ranked high particularly in the commentary, translation with notes, and translation on the original works etc. I suggested adopting conception of supper works, that is, family of works and using uniform title as a connective device between the works, that is, an authorized access point of RDA to apply FRBR model of the Five Classics and Four Books. Also I exemplified the description of uniform title in 630 field as subject added entry.

• Metals and materials international
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• v.24 no.6
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• pp.1221-1231
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• 2018

The effect of strain aging on tensile behavior and properties of API X60, X70, and X80 pipeline steels was investigated in this study. The API X60, X70, and X80 pipeline steels were fabricated by varying alloying elements and thermomechanical processing conditions. Although all the steels exhibited complex microstructure consisting of polygonal ferrite (PF), acicular ferrite, granular bainite (GB), bainitic ferrite (BF), and secondary phases, they had different fractions of microstructures depending on the alloying elements and thermomechanical processing conditions. The tensile test results revealed that yielding behavior steadily changed from continuous-type to discontinuous-type as aging temperature increases after 1% pre-strain. After pre-strain and thermal aging treatment in all the steels, the yield and tensile strengths, and yield ratio were increased, while the uniform elongation and work hardening exponent were decreased. In the case of the X80 steel, particularly, the decrease in uniform elongation was relatively small due to many mobile dislocations in PF, and the increase in yield ratio was the lowest because a large amount of harder microstructures such as GB, BF, and coarse secondary phases effectively enhanced work hardening.

• Steel and Composite Structures
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• v.42 no.3
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• pp.375-388
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• 2022

In this work, limit elastic speed analysis of functionally graded porous rotating disks has been reported. The work proposes an effective approach for modeling the mechanical properties of a porous functionally graded rotating disk. Four different types of porosity models namely: uniform, symmetric, inner maximum, and outer maximum distribution are considered. The approach used is the variational principle, and the solution has been achieved using Galerkin's error minimization theory. The study aims to investigate the effect of grading indices, aspect ratio, porosity volume fraction, and porosity types on limit angular speed for uniform and variable disk geometries of constant mass. To validate the current study, finite element analysis has been used, and there is good agreement between the two methods. The study yielded a decrease in limit speed as grading indices and aspect ratio increase. The porosity volume fraction is found to be more significant than the aspect ratio effect. The research demonstrates a range of operable speeds for porous and non-porous disk profiles that can be used in industries as design data. The results show a significant increase in limit speed for an exponential disk when compared to other disk profiles, and thus, the study demonstrates a range of FG-based structures for applications in industries that will not only save material (lightweight structures) but also improve overall performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.237-238
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• 2023

When primer is applied manually, adhesion performance decreases due to a decrease in primer penetration performance on the surface, and construction period delay may occur due to a long time due to a decrease in work efficiency when a large area is worked using a conventional roller. In addition, in the case of the roller method, precision work in corners and narrow spaces is not possible, so it is urgent to come up with measures to ensure uniform quality. In addition, secondary work occurs to remove fine powder from the surface before primer application, resulting in construction period delay due to the rise of the working stage. Therefore, in this study, equipment was used instead of manual work for primer work, and as a result, penetration performance and adhesion performance were improved about twice. From these results, it was confirmed that favorable results such as improving work speed, securing high quality, improving the working environment, and resolving the shortage of functional workers can be obtained.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.3
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• pp.410-419
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• 2009

The purpose of this study was to develop the functionally improved winter work clothing for the Korean railroad workers. Based on the questionnaires, sample clothing for the Korean railroad workers was produced. The design, materials, and patterns were modified to increase mobility and comfort for workers. Water-repellent treatment was added to the material in order to decrease the dirt and stains while working. Also, reflective strips were added to side seams and hems of the trousers in order to increase the visibility and safety of the workers. In terms of the design and pattern, a circumference of 4.5cm was added to the crotch area in order to minimize tightness on the hip and crotch areas, but no additional circumference was added to the hip area. And a 1cm width dart was inserted between the side seams and yoke in order to add activity. Also three 1.4cm width tucks were used at 2.5cm space on the knees to alleviate tightness at the knees. The prototype was evaluated objectively and subjectively to compare with the existing working uniform. The assessment group consisted of 5 subject groups and 11 expert groups to evaluate external appearance and adaptability of the movements. Subject and panels were asked to evaluate the prototype that followed an ergonomic design and pattern. According to the results, the prototype was evaluated better than the existing working uniform in appearance and adaptability. A field test was conducted to compare the prototype and the existing working uniform. The field tests were performed by 6 workers in the Korean railroad. According to the results, the prototype advanced in terms of adaptability and comfort.

• Journal of the Korean Society of Visualization
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• v.19 no.2
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• pp.56-62
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• 2021

Solid oxide fuel cells (SOFCs) is the high efficiency fuel cell operating at high temperatures ranging from 700-1000℃. Design of the flow paths of the fuel and air in SOFCs is important to improve cell performance and prevent cell degradation. However, the uneven distribution of current density in the traditional type having one inlet and outlet causes cell degradation. In this regard, the parallel flow path with two inlet and outlets was designed and compared to the traditional type based on computational fluid dynamics (CFD) simulation. To check the cell performance, hydrogen distribution, velocity distribution and current density distribution were monitored. The results validated that the parallel designs with two inlets and outlets have a higher cell performance compared to the traditional design with one inlet and outlet due to a larger reaction area. In case of uniform-type paths, more uniform current density distribution was observed with less cross-sectional variation in flow paths. In case of contracted and expanded inflow paths, significant improvement of performance and uniform current density was not observed compared to uniform parallel path. Considering SOFC cell with uniform current density can prevent cell degradation, more suitable design of SOFC cell with less cross-sectional variation in the flow path should be developed. This work can be helpful to understand the role of flow distribution in the SOFC performance.

• Korean Journal of Construction Engineering and Management
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• v.10 no.5
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• pp.76-84
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• 2009

Korea's construction industry experienced no difficulty managing the costs of finishing work items in the apartment housing field thanks to the uniform specification and the standardized costs of finishing work items. Finishing work items have continuously become more high class and differentiated, which has caused the costs of finishing work items to rise. This study identified problems with the cost management when planning finishing work items and choosing their alternatives based on the current process applied to the planning stage of finishing work items. It also found problems with the information management of finishing work items including design, cost, and work information that took place in bulk. Based on the identified problems, the design, cost and work information of finishing work items was integrated so that they could management the costs and information when planning finishing work items and selecting their alternatives. Then a cost-based information management process was suggested for finishing work items by improving each of the project cost management elements. Finally, an information model for finishing work items was built by studying the ways to integrate the information hierarchy and library of finishing work items.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.5056-5078
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• 2018

In this work we propose a compression technique that makes use of linear and perceptually uniform CIE $La^*b^*$ color space in the JPEG image compression framework to improve its performance at lower bitrates. To generate quantization matrices suitable for the linear and perceptually uniform CIE $La^*b^*$ color space, a novel linear Contrast Sensitivity Function (CSF) is used. The compression performance in terms of Compression Ratio (CR) and Peak Signal to Noise Ratio (PSNR), is further improved by utilizing image dependent, variable and non-uniform image sub-blocks generated using a proposed histogram-based merging technique. Experimental results indicate that the proposed linear CSF based quantization technique yields, on an average, 8% increase in CR for the same reconstructed image quality in terms of PSNR as compared to the conventional YCbCr color space. The proposed scheme also outperforms JPEG in terms of CR by an average of 45.01% for the same reconstructed image quality.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.207-212
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• 2007

The concentration profiles of deep energy levels($E_c$ -0.23e V, $E_v$+0.36e V and $E_c$ -0.23e V) in platinum-diffused silicon have generally a sharp gradient in the vicinity of the surface of the silicon wafer. In this work two efficient methods are proposed to obtain the uniform concentration profiles throughout the silicon wafer. One is that the platinum diffusion is carried out at $1000^{\circ}C$ for 1h in oxygen atmosphere. In this case the values of obtained uniform concentration, $1{\times}10^{15}cm^{-3}$ for the $E_c$ -0.23e V level, and 1{\times}10^{14}cm^{-3}$ for the $E_c$ -0.52e V level, are very restricted, respectively. The other is two-step annealing process. The platinum diffusion is carried out at $850{\sim}1100^{\circ}C$ in a nitrogen ambient for 1h and then the annealing is performed at $1000^{\circ}C$ in oxygen ambient after removing platinum-source from the platinum diffused samples. The advantage of this method is that the uniform concentration of these levels required power devices can be controlled by setting the desired temperatures when the platinum diffusion is carried out in nitrogen ambient.