• Steel and Composite Structures
• /
• 제14권5호
• /
• pp.409-429
• /
• 2013

A composite box-girder with corrugated steel webs has been used in civil engineering practice as an alternative to the conventional pre-stressed concrete box-girder because of several advantages, such as high shear resistance without vertical stiffeners and an increase in the efficiency of pre-stressing due to the accordion effect. Many studies have been conducted on the shear buckling and flexural behavior of the composite box-girder with corrugated steel webs. However, the torsional behavior is not fully understood yet, and it needed to be investigated. Prior study of the torsion of the composite box-girder with corrugated steel webs has been developed by assuming that the concrete section is cracked prior to loading and doesn't have tensile resistance. This results in poor estimation of pre-cracking behaviors, such as initial stiffness. To overcome this disadvantage of the previous analytical model, an improved analytical model for torsion of the composite box-girder with corrugated steel webs was developed considering the concrete tension behavior in this study. Based on the proposed analytical model, a non-linear torsional analysis program for torsion of the composite box-girder with corrugated steel webs was developed and successfully verified by comparing with the results of the test. The proposed analytical model shows that the concrete tension behavior has significant effect on the initial torsional stiffness and cracking torsional moment. Finally, a simplified torsional moment-twist angle relationship of the composite box-girder with corrugated steel webs was proposed based on the proposed analytical model.

• Journal of Digital Convergence
• /
• 제18권12호
• /
• pp.571-576
• /
• 2020

When a user visits a specific site through various devices, the hero image located in the main area that can be viewed without scrolling includes multiple slides and has various carousel navigation patterns. While there is a negative perception that the carousel design does not receive the user's choice due to the hidden slide, it can be seen that its usefulness can vary depending on the user's context. In addition, the navigation pattern of the carousel design is the factor that has the greatest influence on the user experience. The left and right arrow navigation pattern, the bottom pagination navigation pattern, the accordion type navigation pattern, the thumbnail type navigation pattern, the divided slide type navigation pattern, and the last. It could be divided into six types of left and right slide navigation patterns.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• 제28권4A호
• /
• pp.497-505
• /
• 2008

Corrugated steel webs resist only shear force because of the accordion effects. The shear force in the web can cause three different buckling mode: local, global, and interactive shear buckling modes. The shear behavior of the corrugated steel webs have been investigated by several researchers. However, shear buckling behavior of the corrugated webs are not clearly explained yet. And, it lead the conservative design. This paper presents shear strength of trapezoidally corrugated steel webs. A series of the tests were also conducted to verified proposed shear strength. Firstly, local, global, and interactive shear buckling equations provided by previous researchers were rearranged as a simple form considering the profiles of the existing bridges with corrugated steel webs. And, global and interactive shear buckling coefficient, and shear buckling parameter for corrugated webs were suggested in this study. Inelastic buckling strength can be determined from buckling curves based on the proposed shear buckling parameter. From the test results of this study and those of previous researchers, it can be found that suggested shear strength provides good estimation of those of trapezoidally corrugated steel webs.

• Proceedings of the Korea Concrete Institute Conference
• /
• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
• /
• pp.39-40
• /
• 2010

The demands for longer span and reduction of story height have greatly increased as building structures become much larger and higher in recent years. Although the development of flexural members for reducing story height or making long span has been studied by many researchers and engineers, there is still a lack of efficient systems that meet these two demands simultaneously. This study aimed at developing a new composite beam system suitable for long span and reduction of story height, and proposed a prestressed composite beam with corrugated web. It has great resistance against non-symmetric construction load due to its strong out-of-plane shear strength with relatively small member height as well as good constructability and economic efficiency by removing/minimizing form work. The corrugated webs also make accordion effect introducing larger effective prestressing force to top and bottom flanges, which causes larger upward camber reducing the member deflection. Five full-scale specimens with key test parameters, which are web sectional shapes and number of drape points, were tested to understand their flexural behavior and to verify the performance of the proposed method. The experimental test results showed that the proposed prestressed composite beam had greater flexural strength and stiffness than the ordinary non-prestressed composite beam.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• 제33권4호
• /
• pp.1327-1336
• /
• 2013

In this study, the effects of corrugated webs on the ultimate behavior of horizontally curved I-shaped girders are investigated. Because of the geometric characteristics of corrugated plates, corrugated webs can be used for enhancing torsional and warping stiffness of plate girders. Many researches have been conducted to study the effects of corrugated webs on the ultimate behavior of straight girders. But, the studies of the ultimate behavior of horizontally curved girders with corrugated webs, which generally show out-of plane behavior manly, have been rarely performed so far. By performing inelastic-nonlinear analysis, the ultimate behavior of curved girders with corrugated webs is studied in this paper. Laterally unsupported length and subtended angle of girders, and length of height of corrugation of webs are considered as the geometric parameters which would be expected to affect the ultimate behavior. By this analytical study with considering the geometric parameters, the changes of ultimate behavior and load carrying capacity of curved girders with corrugated webs are investigated. Also, the effects of corrugated webs on the increase of load carrying capacity for curved girders are studied with comparing to the capacity of general curved girders with flat webs. According to the analytical results, corrugated webs can be used to increase the ultimate load carrying capacity of curved girders, because of their high torsional and warping stiffness. But, it is also indicated that they may decrease the load carrying capacity of curved girders which have relatively small subtended angle or initial curvature, because of an accordion effect.

• Journal of the Korea institute for structural maintenance and inspection
• /
• 제18권3호
• /
• pp.10-19
• /
• 2014

Corrugated steel plates are made by fabricating thin steel plates to have trapezoidal or sinusoidal corrugation, and the corrugated plates are able to maintain high out-of-plane rigidity even when they are used instead of thick flat plates. Also, corrugated steel plates have almost no axial rigidity due to the accordion effect. Thus, if they are applied to the webs of plate girders, designing can be easily conducted so that the webs bear only shear stresses. However, unlike flat plates, the shear buckling of corrugated steel plates has very complex characteristics where buckling occurs due to the interaction of local and global buckling, besides local buckling and global buckling. For the investigation of the cause and characteristics of this interactive buckling, studies on sinusoidal corrugated steel plates are fewer than studies on trapezoidal corrugated steel plates. Therefore, in this study, the shear buckling characteristics of sinusoidal corrugated steel plates and the occurrence pattern of interactive buckling were investigated. For the calculation of shear buckling strength, a finite element program was used, and the analysis results were compared with the exact solution. In addition, the characteristics of buckling stress change and the change of buckling mode shape depending on corrugation thickness and shape parameter were analyzed, and by comparing these results with the results of a theoretical equation, the timing of buckling mode change was analyzed.

• Journal of the Korean association of regional geographers
• /
• 제3권1호
• /
• pp.155-163
• /
• 1997

The Mongolian ger is ideally suited to the mongol's steppe climate and the nomadic way of life. This is a multipurpose dwelling which can be easily collapsed, transported to another place and put up again fully preserving its original shape. The pastoral nomadic ger has two key components: the wooden framework and the felt cover. The wooden parts are the walls(khana), the long poles(un), the smoke escape(toono) and its supports(bagana). One wall consists of 10-15 branches of willow tree. each about 1.5m high bound together in a way making it possible to fold it for transportation and then unfold it like an accordion. The unfolded walls are connected to form a circle. The long poles(un) are fastened to the upper part of the walls, with the other end passed through the toono hole, the only sky window and smoke escape through it from the ger. The toono is propped up by two posts, called bagana. All this forms the wooden framework of the ger, which is covered with felt. When the herders fire up their metal stoves, the temperature inside the ger becomes quite comfortable. Because the nomads live in a climate where there is only one growing season in a year, they do not make long migrations to new pastures. Livestock subsist on standing vegetation for eight months of the year. The basic pasture migration strategy is to leave enough standing vegetation at the end of the growing season in September to suffice until the new growth appears the following May. Mongolians use a type of compressed tea leaf that is called "brick" tea in English because it is rock solid and roughly the shape of a brick. And they consume a larger percent(88%) of fat from animal products such as meat, milk, butter, and cheese than any other people in the world. Milk products made from the milk of sheep, yak, and goats are major foods in the nomad's diet, but they are produced mainly in summer when all the animals are lactating. Mongolians made their special nomadic food culture on the steppe.

• 한국해양학회지
• /
• 제22권2호
• /
• pp.105-118
• /
• 1987

A series of anchor stations were occupied along the Keum EAstuary during six different periods of tidal and fluvial regimes. The results clearly show that the formation and evolution of the turbidity maximum play an important role in the sedimentary processes in this environment. The turbidity maximum in the Keum Estuary is primarily related to the tidal range at the mouth and is caused by the resuspension of bottom sediments. In this estuary, the turbidity maximum is not a permanent feature and shows semidiurnal, fortnightly and seasonal variations. Repetition of deposition and resuspension of fine sediments occur in response to the variation in current velocity associated with semidiurnal tidal cycles. The core of turbidity maximum shifts landward or seaward accordion to the flood-ebb succession. The turbidity maximum also shows a fortnightly variation in response to the spring-neap cycles. Thus, the turbidity maximum degenerates during neap-tide and regenerates during spring-tide. The freshwater discharge is also an important factor in the formation and destruction of the turbidity maximum. The increase in freshwater discharge in rainy season can create an ebb-dominant current pattern which enhances the seaward transport of suspended sediments, resulting in the shortening of residence time of suspended materials in the estuary. Thus, under this high discharge condition, the turbidity maximum exists only during spring-tide and starts to disappear as the tidal amplitude decreases.

• Journal of Food Hygiene and Safety
• /
• 제11권1호
• /
• pp.57-70
• /
• 1996

This paper intends to investigate commercial fish and shellfish 25 species (fish 8 species, shellfish 7 species, crustacean 3 species, moluse 4 species and echinodermata) for the distribution of sanitary indicator organisms (total viable counts, coliforms, staphylococci, vibrios, and enterococci) and distributional change of indicator organisms accordion to storage temperature and period. The logarithmic mean of total viable counts for total commercial fish and shellfish 25 species was 5.41$\pm$.026 CFU/g, and in accordance with fish and shellfishes, crustacean 6.76$\pm$0.67 CFU/g, shellfish 5.67$\pm$0.56 CFU/g, echinodermata 5.47$\pm$1.50 CFU/g, fish 5.02$\pm$0.38 CFU/g, and mollusc 5.03$\pm$0.65 CFU/g. The logarithmic mean of enterococci was 2.36$\pm$0.37 CFU/g, and in accordane with fish and shellfish, crustacean 3.44$\pm$2.12 CFU/g, shellfish 3.87$\pm$0.45 CFU/g, echinodermata 3.38$\pm$0.0 CFU/g, fish 2.16$\pm$0.41 CFU/g and mollusc 0.01$\pm$0.0 CFU/g. The logarithmic mean of vibrios was 1.60$\pm$1.59 CFU/g, and in accordance with fish and shellfish, crustacean 4.23$\pm$1.11 CFU/g, shellfish 3.58$\pm$0.90 CFU/g, echinodermata 1.64$\pm$0.34 CFU/g, fish 1.79$\pm$0.67 CFU/g and mollusc 1.07$\pm$0.61 CFU/g. The logarithmic mean of staphylococci was 1.60$\pm$1.59 CFU/g, and in accordance with fish and shellfish, shellfish 0.01$\pm$0.00 CFU/g, echinodermata 3.51$\pm$0.60 CFU/g, fish 1.68$\pm$0.64 CFU/g, crustacean 0.34$\pm$0.33 and mollusc 3.90$\pm$0.11 CFU/g. The logarithmic mean of coliformas was 2.52$\pm$0.32 CFU/g, and in accordance with fish and shellfish, echinodermata 3.58$\pm$1.89 CFU/g was highest, shellfish 3.25$\pm$0.30 CFU/g, crustacean 3.23$\pm$0.49 CFU/g, fish 2.18$\pm$0.63 CFU/g, peeled shellfish 1.80$\pm$0.51 CFU/g and mollusc 1.55$\pm$0.95 CFU/g. As the results of research of the change of the contaminate indicator microflora in working with storage period at 1$0^{\circ}C$, 2$0^{\circ}C$ and 3$0^{\circ}C$, total viable counts was increased without storage temperature and enterococci were decreased slowly at 1$0^{\circ}C$, but increased at 20 and 3$0^{\circ}C$. Vibrios were decreased slowly at 1$0^{\circ}C$, decreased at 2$0^{\circ}C$ and 3$0^{\circ}C$in 2 days after increased rapidly. Staphylococci were increased promptly without storage temperature in 2 days, then the total viable counts were maintained. Coliforms were increased at 1$0^{\circ}C$ by 7 days, then decreased or maintained after 14 days, changed at 2$0^{\circ}C$ in accordance with fish species in 2 days, then returned to the initial total viable count, and decreased rapidly at 3$0^{\circ}C$ on 2 days. By the way, there were no difference among the species.