• Steel and Composite Structures
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• v.21 no.5
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• pp.1157-1182
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• 2016

A newly puzzle shape of crestbond rib shear connector is a type of ductile perfobond rib shear connector. This shear connector has some advantages, including relatively easy rebar installation and cutting, as well as the higher shear resistance strength. Thus, this study proposed a newly puzzle shape of crestbond rib with a "${\mho}$" shape, and its shear resistance behaviors and shear strengths were examined using push-out tests. Five main parameters were considered in the push-out specimens to evaluate the effects of shear resistance parameters such as the dimensions of the crestbond rib, transverse rebars in the crestbond dowel, concrete strength, rebar strength, and dowel action on the shear strength. The shear loading test results were used to compare the changes in the shear behaviors, failure modes, and shear strengths. It was found that the concrete strength and number of transverse rebars in the crestbond rib were significantly related to its shear resistance. After the initial bearing resistance behavior of the concrete dowel, a relative slip occurred in all the specimens. However, its rigid behavior to shear loading decreased the ductility of the shear connection. The cross-sectional area of the crestbond rib was also shown to have a minor effect on the shear resistance of the crestbond rib shear connector. The failure mechanism of the crestbond rib shear connector was complex, and included compression, shear, and tension. As a failure mode, a crack was initiated in the middle of the concrete slab in a vertical direction, and propagated with increasing shear load. Then, horizontal cracks occurred and propagated to the front and rear faces of the specimens. Based on the results of this study, a design shear strength equation was proposed and compared with previously suggested equations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.3
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• pp.338-348
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• 2004

The present study is conducted to investigate the effect of rib arrangements on an impingement/effusion cooling system with initial crossflow. To simulate the impingement/effusion cooling system, two perforated plates are placed in parallel and staggered arrangements with a gap distance of 2 times of tile hole diameter. Initial crossflow passes between the injection and effusion plates, and the square ribs (3mm) are installed on the effusion plate. Both the injection and effusion hole diameters are 10mmand Reynolds number based on the hole diameter and hole-to-hole pitch are fixed to 10,000 and 6 times of the hole diameter, respectively. To investigate the effects of rib arrangements, various rib arrangements, such as 90$^{\circ}$transverse and 45$^{\circ}$angled rib arrangements, are used. Also, the effects of flow rate ratio of crossflow to impinging jets are investigated. With the initial crossflow, locally low transfer regions are formed because the wall jets are swept away, and level of heat transfer rate get decreased with increasing flow rate of crossflow. When the ribs are installed on the effusion plate, the local distributions of heat/mass transfer coefficients around the effusion holes are changed. The local heat/mass transfer around the stagnation regions and the effusion holes are affected by the rib positions, angle of attack and rib spacing. For low blowing ratio, the ribs have adverse effects on heat/mass transfer, but for higher blowing ratios, higher and more uniform heat transfer coefficient distributions are obtained than the case without ribs because the ribs prevent the wall jets from being swept away by the crossflow and increase local turbulence of the flow near the surface. Average heat transfer coefficients with rib turbulators are approximately 10% higher than that without ribs, and the higher values are obtained with small pitch of ribs. However, the attack angle of the rib has little influence on the average heat/mass transfer.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1114-1118
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• 1999

Barrier rib for the plasma display panel(PDP) was made by photolithographic process utilizing photosensitive barrier rib paste. The barrier rib paste was prepared by first dissolving ethylcellulose(binder polymer) in butyl carbitol(BC)/butyl carbitol acetate(BCA) =30/70 wt % mixture solvent at 15 wt % concentration. To this solution a mixture of functional monomers consisted of tripropyleneglycol diacrylate/ pentaerythritol triacrylate = 50/50 wt %, Irgacur 651 photoinitiator, and barrier rib powder were added and then the whole mixture was mixed in the three roll mill for 2 hr. The effect of component and concentration of photosensitive barrier paste on the photolithographic process was studied. After optimization of the paste formulation and photolithographic process, barrier rib could be obtained with good resolution up to $100{\mu}m$ height.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.545-550
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• 2000

Bond between reinforcing bars and the surrounding concrete is supposed to safely transfer load in the design process of reinforced concrete structures. Bar with high relative rib area will be studied further not only static load but also dynamic loading conditions to sustain better performance of bond for reinforced concrete structures under earthquake. To determine the bond behavior of high ribbed bars in beam and column joints under repeated loads, 31 pullout specimens were tested. Bond strength increases as relative rib area increases. Also the effect of relative rib area on bond is larger in cyclic loading than in monotonic loading.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.734-743
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• 1999

The local Nusselt numbers have been measured for a round turbulent jet impinging on the concave surface with and without rib. Liquid crystal/transient method was used to determine the Nusselt number distributions along the surface. The temperature on the surface was measured using liquid crystal and a digital color image processing system. The experiments were made for the jet Reynolds number (Re) 23,000, the dimensionless nozzle-to-surface distance (L/d) from 4 to 10, the dimensionless surface curvature (d/D) 0.056, and the rib type (height ($d_1$) 0.2 cm, pitch (p) from 1.2 to 3.2 cm). It was founded that only when $L/d{\geq}6$, the average Nusselt numbers on the concave surface with rib are higher than those without rib, mainly due to an increase in the turbulent intensity caused by the effect of rib attached to the wall surface. It was realized that the rib attached to the concave surface may no longer enhance the heat transfer rate or even lowers it depending on the rib type and flow conditions. In addition, the results by the steady-state method using the gold-film Intrex were in good agreement with those by the transient shroud method.

• Journal of Korean Society of Steel Construction
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• v.13 no.6
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• pp.621-629
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• 2001

This study consists of static and fatigue tests to evaluate the behavior on the field splice joint of longitudinal rib in orthotropic steel deck specimens. Specifically, static and influence surface tests are performed for the stress distribution at the scallop area and high-strength bolt connection of longitudinal rib to examine the existence of handhole cover plate and the effect of eccentric loads. The ultimate strength of the field splice joint of longitudinal rib is obtained. In fatigue tests, cracks are observed at the scallop in the lower level test and the catastrophic failure of longitudinal rib is occurred following the failure of handhole cover plate in the higher level test. This study gives a basis for the better understanding of the field splice joint of longitudinal rib.

• Journal of the Korean Society of Food Culture
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• v.21 no.2
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• pp.161-165
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• 2006

This study was examined the contents of solid, calcium, phosphorous, magnesium, protein, amino acid and collagen in beef leg and rib bone soup by various boiling time(1, 2, 4, 8, 12 hours). The results were as follows; as the boiling time increased, contents of solid, calcium, phosphorous, magnesium, protein, amino acid and collagen were increased. However, the boiling time increased, cloudiness (T%) was decreased. When we compared beef bone leg with the rib bone soup, rib bone soup was much nutritional contents than leg bone soup. In sensory evaluation of the soup boiled for 12 hours, added with 0.8% salt, rib bone stew was highly evaluated than leg bone soup.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.453-460
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• 2013

The surface roughness and heat transfer enhancement devices are known to increase the performance of a flat plate soar collector. This study includes the experiments on the effect of the several heat transfer enhancement devices inserted in duct to simulate the flat-plate solar collector. Experiment was basically at a constant heat flux on the upper duct wall. Inserted heat transfer enhancement devices are Chamfered rib $10^{\circ}$, Chamfered rib $20^{\circ}$, Rib & Groove and Rib & Dimple. Reynolds number is in the range of 2,300 to 22,000 which corresponds to turbulent regime. With the heat transfer enhancement devices, heat transfer would increase by the secondary flow and the increase of the heat transfer area. Pressure drop also increases with the insertion of the enhancement devices. Rib & Dimple model is the best in heat transfer enhancement, however, Chamfered rib $10^{\circ}$ model is the lowest in the pressure drop. Considering the heat transfer enhancement simultaneously with low pressure drop increase, performance factor was the best for the Chamfered rib $10^{\circ}$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.2
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• pp.109-115
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• 2017

Using the computational fluid dynamics (CFD) technique, we performed a numerical simulation in anodesupported solid oxide fuel cell (SOFC). The effect of gas channel/rib width on the cell performance and temperature uniformity was investigated in planar type SOFC. The open source CFD toolbox, OpenFOAM, was used as a numerical analysis tool. As a result, the effect of gas channel/rib width on the cell performance and temperature uniformity was not significant if the oxygen depletion is not occurring. On the other hand, the usage of a wide rib and operation at high current density may lead to performance degradation due to oxygen depletion.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.590-598
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• 2005

The present study has been conducted to investigate the effect of discrete ribs and rotation on heat/mass transfer characteristics in a two-pass square duct with $90^{\circ}-rib$ turbulators. The rib turbulator has a square cross section of 1.5 mm. The rib height-to-hydraulic diameter ratio $({e/D_{h})$ is 0.056, and the rib pitch-to-rib height ratio (p/e) is 10. The gap width is the same as the rib height. The rotation number ranges from 0.0 to 0.2 while Reynolds number is fixed to 10,000. In a stationary duct, the heat/mass transfer on the surfaces with discrete ribs is enhanced because the gap flow promotes local turbulence and flow mixing near the ribbed surface. In a rotating duct, the gap flow affects differently the heat/mass transfer on leading and trailing surfaces with discrete ribs. On the leading surface of the first pass, heat/mass transfer is increased due to the gap flow. On the trailing surface of the first pass, however, heat/mass transfer is decreased because the gap flow disturbs reattachment of main flow. The phenomenon, that is, the difference of heat transfer between the leading and the trailing surfaces is distinctly presented by rotation.