• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4087-4092
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• 2014

The gangway connection of the articulated high speed railway vehicles (HSRV) is a double wrinkled rubber component to seal the air of the corridor under a range of angular deviations between the carriage end parts. From the results of non-linear structural analysis, one of the severe loading conditions for the connection is mixed mode (rolling+yawing) angular displacements while passing through the small-radius curved siding track of the HSRV depot. In this study, to ensure the safety enhancement of the component, the optimal design for the cross section of that was performed using the Solid Isotropic Material with Penalization (SIMP) method. Nonlinear finite element analysis confirmed that the decreases in the maximum principal strain of the optimized design under rolling and mixed modes are 68% and 39%, respectively, compared to the initial design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6504-6513
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• 2013

The result can be summarized as follows. First, the following periodically changing characteristics were examined:roof form(gambrel/hipped-flat-gable), structure of roof and wall(wood-framed-cement masonry-RC-Light iron framed), roof material(thatched-tiled-slate-cement/steel sheet-asphalt/sandwich panel/mortar water-proofing), wall material(clay plaster/lime plastered-dressing tile/bricks-painting on the cement plastering-native stone dressing/siding/tile), fence material(masonry of stone and cement bricks), and courtyard materials(clay and concrete). Secondly, the regionally changing characteristics of those elements, rural housing structure, roof form, roof structure material, wall finishing material, fence and courtyard material in the outer space, differed according to the location of rural housing, i.e.north, middle, south region. The changing characteristics of both the roof structure and wall structure are similar to those of the three regions.

• Journal of the Korean housing association
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• v.21 no.1
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• pp.23-30
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• 2010

The purpose of this study is to analyze the elevations of standard rural house designs after the 1990's. Various types of analysis were carried out on a total of 18 different sizes and 50 types of designs with p'yong sizes ranging from 12 to 44. The objects of analysis are the various elevations & the roof types that were supplied in the standard rural house design according to each year 1995 (8 sizes 20 types), 1997 (8 sizes 8 types), 1998 (l size 8 types), 2000 (2 sizes 4 types), 2001 (2 sizes 4 types), and 2004 (3 sizes 6 types). Results from the analysis demonstrate that (1) The gable roof has been used as the roofing type for standard rural house design since 1990. However the roof types of the standard rural house design includes only a few different types of gable roofs and roof materials(most roof types use asphalt shingle). (2) While most front elevations have been altered from asymmetrical to symmetrical most rear elevations have evolved from symmetrical to asymmetrical proportions since the 1990's (3) While siding materials and red-brick were most commonly used the main outer-wall materials prior to 2000, environmentally-friendly materials have been used as outer-wall materials since 2000. (4) In terms of the analysis of outer-wall objects before 2000 the walls were even, yet after 2000 these outer-walls evolved to become concave-convex walls. In other words, the evolution of the outer-wall has included a variety of wall types.

• Journal of The Korean Astronomical Society
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• v.49 no.1
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• pp.37-44
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• 2016

The Korea Microlensing Telescope Network (KMTNet) is a wide-field photometric system installed by the Korea Astronomy and Space Science Institute (KASI). Here, we present the overall technical specifications of the KMTNet observation system, test observation results, data transfer and image processing procedure, and finally, the KMTNet science programs. The system consists of three 1.6 m wide-field optical telescopes equipped with mosaic CCD cameras of 18k by 18k pixels. Each telescope provides a 2.0 by 2.0 square degree field of view. We have finished installing all three telescopes and cameras sequentially at the Cerro-Tololo Inter-American Observatory (CTIO) in Chile, the South African Astronomical Observatory (SAAO) in South Africa, and the Siding Spring Observatory (SSO) in Australia. This network of telescopes, which is spread over three different continents at a similar latitude of about -30 degrees, enables 24-hour continuous monitoring of targets observable in the Southern Hemisphere. The test observations showed good image quality that meets the seeing requirement of less than 1.0 arcsec in I-band. All of the observation data are transferred to the KMTNet data center at KASI via the international network communication and are processed with the KMTNet data pipeline. The primary scientific goal of the KMTNet is to discover numerous extrasolar planets toward the Galactic bulge by using the gravitational microlensing technique, especially earth-mass planets in the habitable zone. During the non-bulge season, the system is used for wide-field photometric survey science on supernovae, asteroids, and external galaxies.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.195-207
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• 2007

The urban railways connecting between the inner city and suburb of Seoul metropolitan area, has lost the competitiveness against cars because too many stops deteriorated operating speed and passenger's level of service. This paper suggests that an express train should be introduced into the urban railway system in order to sort out such a complication. There are two considerations in the present study. Firstly, train schedule problem should be taken into account. In this regard, a new model for urban railway system was developed by revising the existing models dealing with single line freight railway. Approximate branch and bound algorithm based on conflict group rather than a single conflict was adopted. Consequently, it was found that the time saving in calculating the optimal schedule is the most meaningful contribution of the algorithm. The second consideration is associated with the application of the model. A case study was carried out using the actual operation data from Ansan line. In conclusion, the operation speed of the line can increase considerably with minimal number of new sidings.

• Journal of the Korean Wood Science and Technology
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• v.37 no.1
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• pp.29-36
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• 2009

Recycling of wood wastes or residues is a good solution for a shortage of wood resources and a rise in the price. Shipbuilding wood wastes were almost used to produce the boards by milling. However, considering the economic value and insufficient resource, recycling with milling is dissatisfied method. This study has been carried out to investigate the recycling possibility of shipbuilding wood waste. There are two kinds of shipbuilding wastes: plywood waste and solid waste. From the results of this study, the following conclusions have been made: 1. Bending properties of plywood and laminated plywood lumber were tested by Korean Standard. 2. The main fracture mode of plywood waste and laminated plywood lumber is that of simple tension. 3. The recommended application for the recycling of shipbuilding wood waste are outdoor wood furnishings, indoor wood furnishings and some wooden building construction materials: interior raw material, wooden pallet, siding, paneling, flooring. picnic table, deck components, porch swing, landscaping timbers, residential fencing, patios, and boardwalks etc.

• Journal of Korea Foundry Society
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• v.31 no.5
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• pp.293-301
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• 2011

Representative magnesium alloys applied to the die-casting are AZ91, AM60, etc., and the application of these alloys is restricted to components operating at moderate temperatures, due to grain boundary siding of ${\beta}$-phase($Mg_{17}Al_{12}$) at temperatures above $120^{\circ}C$. Heat-resistant magnesium alloys such as AE42, AE44 have been developed, but that have been too burdensome to produce because of the expensive rare earth materials. Research work for the development of low-priced heat-resistant magnesium alloy is actively in progress and positive results are being reported. This study aims to investigate the effect of Ca additions on mechanical properties of Mg-4Al-2Sn heat resistant magnesium alloys. Mg-4Al-2Sn alloys with Ca (0wt.%, 0.3wt.%, 0.7wt.%, 1wt.%) have been produced through the die-casting process for the development of low-priced heat-resistant magnesium alloy, and high temperature tensile tests are performed using the specimens. The results showed that mechanical properties of Mg-4Al-2Sn-xCa increased with the addition of Ca up to 0.7wt.% Ca and further addition of Ca deteriorated the mechanical properties of the alloys. A significant amount of porosity was observed at the sample with 1wt%. Ca and the longer freezing range of the alloy was believed to cause the formation of porosity.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.539-549
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• 2017

This paper proposes an analytical methodology of station capacity calculation on high - speed railway. Our method explicitly takes into account the effect of the number of sidings and the combination of train halting patterns (stop - stop, pass - stop, stop - pass, pass - pass) on the capacity of a station. To verify the reliability of our model, we conducted capacity analysis of selected stations using the Railsys simulator. We found that the difference in calculated capacity between our model and Railsys was less than 10%. After Monte Carlo simulation, our model was determined to be a good one. In addition, the consistency in capacity between our model and the train-path allocation program (Korea Rail Network Authority) was statistically significant.

• Journal of the Korean association of regional geographers
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• v.22 no.2
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• pp.369-382
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• 2016

The studies on the rural housing have focused on folk housing, but this study focuses on the contemporary rural housing with special reference to the roof types/materials and the outer wall materials. The research area of this study is the fourteen rural settlements in Jeju Island. The hip roof type, the hip/flat roof type, the simple-flat roof type, the gable roof type, and the eyebrow-and-flat roof type are the most frequent roof types. Among the roof materials, the precoated steel plate, the artificial slate, the cement, the cement/roof tile, and the cement/artificial slate are the most frequent materials. The cement holds more than a half of the outer wall materials, and the cement/basalt rock, the tile/cement, the tile, and the diverse siding are the next frequent outer wall materials. The comparison of the rural housing reveals that there are some clear differences between Jeju Island and Gyeongnam Province in terms of the roof types and the outer wall materials.

• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.153-160
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• 2010

We modified the optical system of 500 mm wide-field telescope of which point spread function showed an irregularity. The telescope has been operated for Near Earth Space Survey (NESS) located at Siding Spring Observatory (SSO) in Australia, and the optical system was brought back to Korea in January 2008. After performing a numerical simulation with the tested value of surface figure error of the primary mirror using optical design program, we found that the surface figure error of the mirror should be fabricated less than root mean square (RMS) $\lambda$/10 in order to obtain a stellar full width at half maximum (FWHM) below $28\;{\mu}m$. However, we started to figure the mirror for the target value of RMS $\lambda$/20, because system surface figure error would be increased by the error induced by the optical axis adjustment, mirror cell installation, and others. The radius of curvature of the primary mirror was 1,946 mm after the correction. Its measured surface figure error was less than RMS $\lambda$/20 on the table of polishing machine, and RMS $\lambda$/15 after installation in the primary mirror cell. A test observation performed at Daeduk Observatory at Korea Astronomy and Space Science Institute by utilizing the exiting mount, and resulted in $39.8\;{\mu}m$ of stellar FWHM. It was larger than the value from numerical simulation, and showed wing-shaped stellar image. It turned out that the measured-curvature of the secondary mirror, 1,820 mm, was not the same as the designed one, 1,795.977 mm. We fabricated the secondary mirror to the designed value, and finally obtained a stellar FWHM of $27\;{\mu}m$ after re-installation of the optical system into SSO NESS Observatory in Australia.