• Journal of Korean Society of Steel Construction
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• v.27 no.4
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• pp.377-386
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• 2015

In this study, inelastic buckling strength of HSA800 steel columns were tested to investigate the applicability of current column curve (KBC2009, 2010 AISC-LRFD) to HSA800 steel. Key test variables included width-thickness ratio, plate-edge restraints, and column slenderness ratio. Specimens made of ordinary steel (SM490) were also tested for comparison purposes. All the concentrically loaded HSA800 specimens exhibited sufficient buckling strength compared to the current column curve, but some of SM490 specimens showed understrength. This difference can be explained by the lower residual stress present in HSA800 specimens.

• Proceedings of the KSRS Conference
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• v.1
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• pp.483-486
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• 2006

The study describes the monitoring of the Bay of Bengal as a ballast water exchangeable sea using MODIS/Aqua-derived diffuse attenuation coefficient (K(490)) synchronized with in situ ballast water sampling and analysis along the LNG carrier's route between Japan and Qatar from 2002 to 2005. Based on the relationship between K(490) and corresponding in situ plankton cell densities, the Bay of Bengal is recognized as a ballast water exchangeable sea to meet the regulation of ballast water performance standard of International Maritime Organization (IMO). Furthermore the Bay of Bengal with more than 200m depth and more than 200 nautical mile distance from shore is extracted based on the regulation of ballast water exchange area of IMO. However, an anomalously high K(490) area is found off the coast of Sri Lanka during the northeast monsoon in 2005, which corresponds higher cell densities than the criterion set by the regulation of IMO. The phenomenon of high cell density in the Bay of Bengal seems to be related with the phytoplankton bloom during the northeast monsoon. Seasonal and annual variability of phytoplankton bloom will be investigated to establish an early routing system for avoiding the high cell density area in advance.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.695-700
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• 2006

This study investigates the effects of the material properties and the fatigue behavior in the SM490A material specimens due to the low-temperature atmosphere. In the fatigue behavior, the low-temperature affects the fatigue life. As the temperature get low, the fatigue limit increase, also As the yield strength and the tensile strength increase, the impact absorbed energy decrease. The difference of fatigue lift represents to normal distribution and it is larger between the room temperature and the low temperature, but in the result of the cumulative density function, the effect of temperature is not too large on it.

• Fire Science and Engineering
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• v.27 no.6
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• pp.21-25
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• 2013

Fire resistance steel, grading 490 MPa, had developed by using Thermo-mechanical control process (TMCP) and it has better performance at welding, seismic resistance than those of the ordinary structural steel, But the fire resistance performance is required to verify against the ordinary fire resistance, FR 490. Therefore this study was done to make database of mechanical properties at high temperature and to evaluate the structural stability at high temperature in terms of materials and structural member such as H-section from that of FR 490. The result of this study was that the structural stability of TMCP was lower than that of ordinary FR 490 at the range up about $700^{\circ}C$.

• Journal of Welding and Joining
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• v.27 no.2
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• pp.76-81
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• 2009

Tandem GMAW is one of the high performance welding process and used in many industries to increase the productivity. An evaluation is presented of the mechanical properties and microstructural characteristics of the Tandem GMAW and conventional Single GMAW welds in 30mm thickness 490MPa grade steel by comparison method. Welding sequence and bead with and hight was kept, avoiding the effect of the bead shape and welding sequence. Tension, bending, hardness and Charpy impact test results of Tandem GMAW met the requirement of specification and showed similar distribution with conventional Single GMAW. Volume fraction of ferrite phase in weld metal showed little difference between Tandem GMAW and Single GMAW

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.463-471
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• 2014

As building height and span is getting taller and longer, the researches to increase material's strength and serviceability are continuously performed. This study evaluated mechanical and chemical properties of newly developed high-strength steel (HSS) for building structures, namely HSA800 and verified cost-effectiveness and applicability of HSS for a tall building by comparing the analysis results of normal strength steel (SM490) model. HSA800 was manufactured by TMCP to have a good weldability in spite of HSS and satisfied Korean Industrial Standards (KS). The analysis results for evaluating cost-effectiveness show that total steel quantity could be saved approximately 30% when using HSS compared to SM490. It is expected that HSA800 will contribute to enhance constructability of building.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.208-208
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• 2002

Relationship between chlorophyll a in the East China Sea and spectral bands (412, 443,490, (510), 555, (676,765) in) of OSMI (Ocean Scanning Multi-Spectral Imager) including the profile multi-spectral radiometer (PRR-800) was studied. The values of remote sensing reflectance (Rrs) at the bands corresponding to the field chlorophyll a in α in the East China Sea were much higher than those in clear waters off California, USA. In case of the particle absorptions related to the chlorophyll a concentration at the spectral bands (440, 670 nm) were much higher in the East China Sea than the ones in the clean waters off California. The normalized water leaving radiances (nLw) at 412, 443, 490, 555 m of OSMI and field chlorophyll a in the East China Sea were correlated each other. According to the results, the relationship between field chlorophyll a and nLw 410 m in OSMI bands was the lowest, whereas that between the field chlorophyll a and nLw 555 nm in the bands was the highest. Reciprocal action between the field chlorophyll a and the band ratio of the OSMI bands (nLw410/nLw555, nLw443/nLw555, nLw490/nLw555) was also studied. Correlation between the chlorophyll a and the band ratio (nLw490/nLw555) was highest in the OSMI bands. Relationship between the chlorophyll a and the ratio (nLw443/nLw555) was higher than one in the nLw410/nLw555. The difference in the estimated chlorophyll α (mg/m3) between OSMI and SeaWiFS (Sea Viewing Wide Field-of-View Sensor) at the special observing stations in the northern eastern sea of Jeju Island in february 25, 2002 was about less than 0.3 mg/m3 within 3 hours. It is suggested that OC2 (ocean color chlorophyll 2 algorithm) be used to get much better estimation of chlorophyll α from OSMI than the ones from the updated algorithms as OC4.

• Journal of Welding and Joining
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• v.23 no.5
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• pp.20-24
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• 2005

Due to the difficulties associated with the supply of steel plates, hot rolled coil (Steel grade: SM490A) is considered fur structural materials in replace of the existing SWS50A-M1. However, it is found that SM490A exhibits a significant anisotropy in terms of impact energy with respect to transverse and longitudinal directions. In this study, an experimental investigation is carried out to examine the relationship between the anisotropy in impact values and the fatigue strengths of SM490A with respect to the rolling direction of test specimens. All test specimens failed around 1,500,000 cycles regardless of the test specimen direction. Therefore, it is found that the anisotropy in impact energy is not related to the fatigue strength of the materials considered in this study. However, the transverse direction specimen showed more rapid brittle fracture mode compared to that of longitudinal direction specimen, and this appears to be related to the lower impact values in transverse direction.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.490-492
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• 2016

급속한 기술환경의 변화와 정보화 사회의 도래에 따라 시스템의 구축 비용보다 더 많은 비용이 유지보수에 투입되고 있다. ERP(SAP)는 공통의 package를 사용하므로 서로 다른 업종, 조직이라 하더라도 통합운영관리가 비교적 용이하다. 통합운영은 고객의 유지보수비용을 줄이고, 유지보수입장에서도 적은 인원으로 효과적인 운영이 가능하게 하다. 하지만, 여기서 나타나는 문제점을 사례를 통해 제시하고 분석하여 그 개선방향을 제시하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.490-493
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• 2010

본 논문에서는 클러스터 측정(Cluster Measurement)과 유전자 알고리즘을 이용한 문서 클러스링 알고리즘을 제안한다. 유전자 알고리즘의 요소를 클러스터링에 대입하고 클러스터 측정을 적합도 함수에 대입하여 문서 클러스터링을 구현하였다. 성능 평가를 위하여 한국일보-20000/한국일보-40075 문서범주화 실험문서집합의 데이터 셋을 이용하였다. 클러스터링 성능 평가 결과 AS Index가 DB Index, RS Index 보다 좋은 성능을 보여준다. 또한 제안한 알고리즘이 K-means 클러스터링 알고리즘에 비교해 안정적으로 좋은 성능을 보여준다.