• International Journal of Aeronautical and Space Sciences
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• 제15권1호
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• pp.20-31
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• 2014

This paper deals with the development of a realistic shape optimization of damaged columns that are subjected to conservative and non-conservative forces, using the Genetic Algorithm (GA). The analysis is based on the design of the most optimized shape of the column under the constraint of constant weight, considering the Static, Vibrational, and Flutter characteristics. Under the action of conservative and non-conservative longitudinal forces, an elastic column loses its stability. A numerical analysis based on FEM has been performed on a uniform damaged column, to compute the fundamental buckling load, vibration frequency, and flutter load, under various end restraints. An optimization search based on the Genetic Algorithm is then executed, to find the optimal shape design of the column. The optimized column references the one having the highest buckling load, highest vibration frequency, and highest flutter load, among all the possible shapes of the column, for a given volume. A comparison is then made between the values obtained for the optimized damaged column, and those obtained for the optimized undamaged column. The comparison reveals that the incorporation of damage in the column alters its optimal shape to only a certain extent. Also, the critical load and frequency values for the optimized damaged column are comparatively low, compared with those obtained for the optimized undamaged column. However, these results hold true only for moderate-intensity damage cases. For high intensity damage, the optimal shape may not remain the same, and may vary, according to the severity of damage.

• Structural Engineering and Mechanics
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• 제56권1호
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• pp.67-83
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• 2015

The load transfer mechanism and load-bearing capacity of cast steel joints for H-shaped beam to square tube column connection are studied based on the deformation compatibility theory. Then the monotonic tensile experiments are conducted for 12 specimens about the cast steel joints for H-shaped beam to square tube column connection. The findings are that the tensile bearing capacity of the cast steel joints for beam-column connection depends on the ring of cast steel stiffener. The tensile fracture happens at the ring of the cast steel stiffener when the joint fails. The thickness of square tube column has little influence on the bearing capacity of the joint. The square tube column buckles while the joint without concrete filled, but the strength failure happens for the joint with concrete filled column. And the length of welding connection between square tube column and cast steel stiffener has little influence on the load-bearing capacity of the cast steel joint. Finally it is shown that the load-bearing capacity of the joints for H-shaped beam to concrete filled square tube column connection is larger than that of the joints for H-shaped beam to square tube column connection by 10% to 15%.

• Steel and Composite Structures
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• 제13권5호
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• pp.409-421
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• 2012

Recently, as the height of building is getting higher, the applications of CFST column for high-rise buildings have been increased. In structural system of high-rise building, The RC core and exterior concrete-filled tubular (CFST) column-beam pinned connection is one of the structural systems that support lateral load. If this structural system is used, due to the minimal CFST column thickness compared to that of the CFST column width, the local moment occurred by the eccentric distance between the column flange surface from shear bolts joints degrades the shear strength of the CFST column-beam pinned connections. This study performed a finite element analysis to investigate the shear strength under eccentric moment of the CFST column-beam pinned connections. The column's width and thickness were used as variables for the analysis. To guarantee the reliability of the finite element analysis, an actual-size specimens were fabricated and tested. The yield line theory was used to formulate an shear strength formula for the CFT column-beam pinned connection. the shear strength formula was suggested through comparison on the results of FEM analysis, test and yield lime theory, the shear strength formula was suggested.

• 건축역사연구
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• 제30권5호
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• pp.7-16
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• 2021

According to 「Hwangnyongsa Temple Central Column Record」 among the remaining documents, under reconstruction the pagoda of Hwangnyongsa&s 9th floor was completed in July 872 on the lunar calendar. At that time, King Kyeongmun worried about sarira under its central column, saying the central column does not move, and then He ordered to lift the central column. So his servants lifted it on November 6th 872 and checked the sarira and put it back on November 25th on the lunar calendar. 「Hwangnyongsa Temple Central Column Record」 did not document how to lift the central column which is tens of meters. therefore, this study inferred the way the central column of the pagoda of Hwangnyongsa was lifted in 872, left as a mystery. For that, this study set various hypotheses and it researched and analyzed hoisting technique that is a way to lift the pagoda of Hwangnyongsa and a column. In conclusion, this study inferred the most suitable hoisting technique for the pagoda of Hwangnyongsa at that time, based on the research and analysis of each chapter.

• Geomechanics and Engineering
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• 제6권2호
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• pp.173-194
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• 2014

Laboratory and field data showed that deep mixed (DM) columns accelerated the rate of consolidation of the soft foundations. Most analyses of consolidation of DM column-improved foundations so far have been based on the elastic theory. In reality, the DM columns may yield due to the stress concentration from the soft soil and its limited strength. The influence of column yielding on the degree of consolidation of the soft foundation improved by DM columns has not been well investigated. A three-dimensional mechanically and hydraulically-coupled numerical method was adopted in this study to investigate the degree of consolidation of the DM column foundation considering column yielding. A unit cell model was used, in which the soil was modeled as a linearly elastic material. For a comparison purpose, the DM column was modeled as an elastic or elastic-plastic material. This study examined the aspects of stress transfer, settlement, and degree of consolidation of the foundations without or with the consideration of the yielding of the DM column. A parametric study was conducted to investigate the influence of the column yielding on the stress concentration ratio, settlement, and average degree of consolidation of the DM column foundation. The stress concentration ratio increased and then decreased to reach a constant value with the increase of the column modulus and time. A simplified method was proposed to calculate the maximum stress concentration ratios under undrained and drained conditions considering the column yielding. The simplified method based on a composite foundation concept could conservatively estimate the consolidation settlement. An increase of the column modulus, area replacement ratio, and/or column permeability increased the rate of consolidation.

• 한국환경농학회지
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• 제11권3호
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• pp.201-208
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• 1992

쓰레기 매립장 침출수를 모래, 연탄제, fly ash 및 활성탄을 각각 충전시킨 column에 8주간 매주 통과시켜 오염물질 제거율을 조사한 결과 COD는 활성탄 column에서 8주동안 평균 83%이상 제거되었으며, 연탄재와 fly ash column에서는 시간이 경과함에 따라 제거되는 비율이 낮아지는 경향이었으나 8주 평균 각각 45% 및 43% 제거되었고, 모래 column에서는 거의 제거되지 않았다. $NH_4\;^+$-N는 모든 column에서 8주 평균 60%이상 제거되었으며, Hardness는 활성탄과 fly ash column에서는 8주간 지속적으로 제거된 반면 연탄재 및 모래 column에서는 불규칙적이었고 특히 8주째에는 거의 제거되지 않았다. $PO_4\;^{3-}$는 1주 이후부터 모든 column에서 불규칙적으로 제거되었으며, 특히 fly ash column에서는 4, 5주째 폐기물 침출수 원액에 비해 $PO_4\;^{3-}$가 4배 높게 나타났으며, $CI^-$ 및 $SO_4\;^{2-}$등의 음이온은 1주 이후부터 모든 column에서 제거되지 않았으며, 이는 충전 물질과 침출수의 pH가 높았기 때문인 것으로 사료되었다. 각 column내 각 오염물질 흡착량을 토대로 각 흡착성분간 상관관계를 검토한 결과 활성탄, fly ash 및 연탄재 column에서는 양이온간에 서로 유의적인 정의 상관이 있었으며 모래 column에서는 유의적인 상관이 없었고, 활성탄과 fly ash column에서는 음이온간에 유의적인 상관이 있었다. 그리고 모든 column에서 양이온과 음이온간에는 대부분 유의적인 상관이 없었다.

• 한국식품과학회지
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• 제22권1호
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• pp.88-93
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• 1990

GLC를 이용 N-TFA n-butyl ester유도제화에 의한 아미노산 분석시 stainless steel packed column으로 효과적인 분리를 할 수 있는 고정상을 찾기 위하여 다음과 같은 2개의 column을 개발하여 표준 아미노산의 N-TFA n-butyl ester 유도체를 분석하였다. Column 1;3.36% OV-17+3.0% SE-30 on chromosorb W HP 100-120 mesh. Stainless steel column $(2m{\times}3mm\;I.D.)$ Column 2;1% NPGS+0.5% OV-17+0.5% SE-30 on chromosorb W HP 100-120 mesh. Stainless steel column $(2m{\times}3mm\;I.D.)$ Column 1에서 histidine을 제외한 19개의 아미노산 peak가 나타났으나 alanine과 valine peak는 분리되지 않았다. Colume 2에서는 15개의 아미노산이 좋은 분리를 이루었고 column 1에서 분리되지 않은 alanine과 valine.이 잘 분리되었으나 column 1에서 분리된 tryptophan, arginine 및 tyrosine이 나타나지 않았다. 분리된 모든 아미노산은 column 1, 2를 막론하고 아미노산 주입량 $1.25{\times}10^{-3}{\mu}mole-1.0{\times}10^{-2}{\mu}mole$의 범위에서 각 아미노산 peak의 높이와 내부표시제 peak 높이와의 비에 대한 주입량으로 나타낸 검정선이 선형을 나타내었고 모두 원점을 지났다. Glutamine, asparagine 및 cystine은 column 1,2에서 모두 glutamic acid, aspartic acid 및 cysteine peak와 일치하는 것으로 보아 N-TFA n-butyl ester 유도체를 만드는 과정에서 염산에 의해 각각 glutamic acid, aspartic acid 및 cysteine으로 전환되는 것으로 사료된다.

• 콘크리트학회논문집
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• 제19권2호
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• pp.209-216
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• 2007

본 연구는 강섬유 보강 초고강도 콘크리트가 적용된 슬래브-기둥 접합부의 구조적 특성을 파악하였다. 2개의 슬래브-기둥 시험체와 4개의 독립 기둥 시험체의 기둥 하중 전달 실험이 수행되었다. 기둥 하중 실험 수행시, 슬래브-기둥 접합부의 실제 구속 상태를 고려하기 위해 슬래브 하중을 적용하였다. 주 변수로는 강섬유 보강 초고강도 콘크리트의 확대 타설이며, 이에 더하여 슬래브의 접합부 구속 효과, 강섬유 보강, 그리고 접합부의 콘크리트 강도 등이 실험을 통해 파악되었다. 또한, ACI Code(2005)와 CSA Standard(2004)의 예측식과 실험 결과를 비교하였다. 슬래브-기둥 접합부를 통한 기둥 하중 전달에 대한 강섬유 보강 초고강도 콘크리트의 효과를 실험을 통해 확인하였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권5호
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• pp.362-368
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• 2004

A new one-column chromatography process, analogous to a four-zone simulated moving bed (SMB), was presented. The basic principle of the process was identical to that of a four-zone SMB. The process consisted of one chromatographic column and four tanks, instead of the four columns in the four-zone SMB (1-1-1-1), and has been used for the separation of two amino acids, phenylalanine and tryptophan, using an ion exchange resin. The operating parameters for the one-column process and four-zone SMB were obtained from equilibrium theory. Computer simulations were used to compare the performances of the new one column process to that of the general four-zone SMB, using Aspen $Chromatography^{TM}$ v 11.1. The differences between the one-column and SMB processes in terms of the purities and yields of phenylalanine and tryptophan were less than 4 and about $6\%$, respectively. The lower purities of the one-column process were due to the loss of the developed concentration profiles in the column when the liquid was stored in tanks. The one-column process gave great flexibility, and would be useful for reconstructing an existing conventional chromatography process to one of a SMB.

• Structural Engineering and Mechanics
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• 제78권5호
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• pp.623-635
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• 2021

Previous studies have suggested the maximum experimental story shear force of beam-column joint frame does not reach its theoretical value due to beam-column joint failure when the column-to-beam moment capacity ratio was close to 1.0. It was also pointed out that under a certain amount of axial force, an axial collapse and a sudden decrease of lateral load-carrying capacity may occur at the joint. Although increasing joint transverse reinforcement could improve the lateral load-carrying capacity and axial load-carrying capacity of beam-column joint frame, the conditions considering varying axial force were still not well investigated. For this purpose, 7 full-scale specimens with no-axial force and 14 half-scale specimens with varying axial force are designed and subjected to static loading tests. Comparing the experimental results of the two types of specimens, it has indicated that introducing the varying axial force leads to a reduction of the required joint transverse reinforcement ratio which can avoid the beam-column joint failure. For specimens with varying axial force, to prevent beam-column joint failure and axial collapse, the lower limit of joint transverse reinforcement ratio is acquired when given a column-to-beam moment capacity ratio.