• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.671-674
• /
• 2008

We investigate the slippage effect in a micro-channel depending on the surface characteristics; hydrophilic, hydrophobic, and super-hydrophobic wettabilities. The micro-scale grooves are fabricated on the vertical wall to make the super-hydrophobic surfaces, which enable us visualize the flow fields near walls and directly measure the slip length. Velocity profiles are measured using micro-particle image velocimetry (Micro-PIV) and compared those in the hydrophilic glass, hydrophobic PDMS, and super-hydrophobic PDMS micro-channels. To directly measure the velocity in the super-hydrophobic micro-channel, the transverse groove structures are fabricated on the vertical wall in the micro-channel. The velocity profile near the wall shows larger slip length and, if the groove structure is high and wide, the liquid meniscus forms curves into the valley so that the wavy flow is created after the grooves.

• Journal of Korean Institute of Industrial Engineers
• /
• v.27 no.2
• /
• pp.197-202
• /
• 2001

The biomechanical analysis of the load carrying effect on different floor surfaces has been conducted. Four different floor surfaces were prepared for ten subjects with each walking at a fixed velocity(1.33 m/sec) while carrying five different loads. The results showed that because of the significant interaction effect between floor slipperiness and the load carrying task, the load carrying effect should be analyzed according to different levels of the floor slipperiness, especially contaminant floors. On oily surfaces, slip distance(SD) and heel velocity (HV) increased whereas stride length(SL) decreased as load increased. In other words, significantly longer SD, faster HV, and no normal gait were found as load increased. As a result, a different protocol should be applied to measure floor slipperiness on oily floors as compared to dry surfaces for tribological approach.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.233.2-233.2
• /
• 2005

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.2A
• /
• pp.285-292
• /
• 2006

In this study, a method determining the local bond-slip model from pure shear test results of CFRP sheet-concrete adhesive joints is proposed and local bond-slip models are presented. Adhesive joints with a specific bond-slip model, which is assumed as multi-linear curve in order to represent arbitary function, are solved numerically. The difference between the solution and test results are minimized for finding the bond-slip model. The model with bilinear curve is also optimized to verify the improvement of multi-linear model. The selected test results are ultimate load-adhesive length curves from a series of adhesive joints and load-displacement curves for each joint. The optimization problem is formulated by physical programming, and the optimized bond-slip model is found using genetic algorithm.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.1
• /
• pp.50-56
• /
• 2003

An experiment was carried out to compare the body weight, shank length, rectal temperature, comb area, abdominal fat, blood parameters and bone traits of capon, slip and intact birds in Taiwan country chicken cockerels. One hundred and sixty-six Taiwan country chicken cockerels were randomly assigned to caponized or intact male groups. Caponized birds were surgically altered at 10 weeks old and raised to 28 weeks old. At 28 weeks of age, the capons were separated into capon and slip groups, depending on the atrophy of the comb and wattle in size. The results showed that body weight and shank length in slips were significantly (p<0.05) greater than in intact birds. Intact birds had the highest (p<0.05）feather scores and the lowest (p<0.05) rectal temperature. Compared with intact birds and slips, capons had a significantly (p<0.05) smaller comb area. Bone percentage, stress and cortical thickness, and bone and ash calcium content and plasma testosterone concentration, in intact birds were the highest (p<0.05) followed by slips and capons. However, intact birds had the lowest (p<0.05) plasma ionized calcium and phosphorus concentrations. Bone and ash manganese contents in capons were significantly (p<0.05)lower than those in others. These findings support the hypothesis that androgenic effects on secondary sexual characteristics are stronger than anabolic growth promoting response. Androgens can directly influence calcium fluxes in male chickens. Caponized caused a reduction in the bone percentage, stress, cortical thickness and bone calcium content.

• Anatomy and Cell Biology
• /
• v.57 no.2
• /
• pp.246-255
• /
• 2024

Knowledge of the superficial radial nerve (SRN) relationship and anatomic variations of the first extensor compartment (1st EC) will contribute to a better outcome of de Quervain tenosynovitis treatment. We dissected 87 embalmed cadaveric wrists to determine the relationship of the SRN, the 1st EC length, distance from the proximal and distal 1st EC borders to radial styloid process (RSP), abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendon slip numbers, and the presence of septum. Our results revealed SRN crossing over the 1st EC in 59.5%. The lateral branch of the superficial radial nerve to the 1st EC midline in most cases (61.9%) except for one specimen, where lateral antebrachial cutaneous nerve was the closest. Distances from proximal and distal 1st EC borders to the RSP were 19.7±4.1 mm and 7.6±1.8 mm, respectively. Extensor retinaculum (ER) width over 1st EC (1st EC length) was 14.8±3.2 mm. Complete and incomplete septa were found in 17.2%, and 42.5%, respectively. The most frequent APL tendon slip number in the compartment was two in overall 47 specimens (54.0%). Almost all compartments (85 specimens; 97.7%) contained one EPB tendon slip. We detected bilateral EPB absence in one cadaver. Moreover, we recorded a tendon slip from extensor pollicis longus traveling into 1st EC bilaterally in one cadaver and observed the EPB muscle belly extension into 1st EC in 9 wrists. Awareness of 1st EC anatomic variations would be essential for successful surgical and nonsurgical outcomes.

• Journal of the Ergonomics Society of Korea
• /
• v.14 no.1
• /
• pp.37-57
• /
• 1995

The purpose of this study was to investigate the elastic effect of deformation and restriction in wearing a support type panty stocking (PS). The study investigated deformation rate in all surface area, deformation rate in local area, length deformation rate, changes in slip and feeling of restriction under the standard laboratory condition. Two healthy adult females in twenties wore four types of PS. The result were as follows : The deformation rate in all surface area was 117 .approx. 132% in wearing support type PS, 157% in wearing mono type PS, due to the intensities of restriction. The deformation rate in local area was in order, course > oblique > wale direction. The largest deformation rate was observed in hip girth. Between the deformation rates in all surface and local areas was a high correlation acknowledged, especially the course direction showed a high correlation. Support type PSs showed more deformation and changes of slip than wool and mono type PS. Especially, changes of slip at the knee appeared greatly. The responses of restriction evaluated from a paired comparison method were in order, JS 2 > KS 4 > KS 9 > KS 5 > KS 1 > KM 3.

• Steel and Composite Structures
• /
• v.16 no.2
• /
• pp.221-231
• /
• 2014

The purpose of this study was to evaluate the cyclic behavior of steel column-tree moment connections used in steel moment resisting frames. These connections are composed of shop-welded stub beam-to-column connection and field bolted beam-to-beam splice. In this study, the effects of beam splice length on the seismic performance of column-tree connections were experimentally investigated. The change of the beam splice location alters the bending moment and shear force at the splice, and this may affect the seismic performance of column-tree connections. Three full-scale test specimens of column-tree connections with the splice lengths of 900 mm, 1,100 mm, and 1,300 mm were fabricated and tested. The splice lengths were roughly 1/6, 1/7, 1/8 of the beam span length of 7,500 mm, respectively. The test results showed that all the specimens successfully developed ductile behavior without brittle fracture until 5% radians story drift angle. The maximum moment resisting capacity of the specimens showed little differences. The specimen with the splice length of 1,300 mm showed better bolt slip resistance than the other specimens due to the smallest bending moment at the beam splice.

• Steel and Composite Structures
• /
• v.17 no.6
• /
• pp.929-949
• /
• 2014

Thirty one push-out tests were carried out in order to investigate the bond behavior between shape steel, steel tube (named steels) and recycled aggregate concrete (RAC), including 11 steel reinforced recycled aggregate concrete (SRRAC) columns, 10 recycled aggregate concrete-filled circular steel tube (RACFCST) columns and 10 recycled aggregate concrete-filled square steel tube (RACFSST) columns. Eleven recycled coarse aggregate (RCA) replacement ratios (i.e., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) were considered for SRRAC specimens, while five RCA replacement ratios (i.e., 0%, 25%, 50%, 75% and 100%), concrete type and length-diameter ratio for recycled aggregate concrete-filled steel tube (RACFST) specimens were designed in this paper. Based on the test results, the influences of all variable parameters on the bond strength between steels and RAC were investigated. It was found that the load-slip curves at the loading end appeared the initial slip earlier than the curves at the free end. In addition, eight practical bond strength models were applied to make checking computations for all the specimens. The theoretical analytical model for interfacial bond shear transmission length in each type of steel-RAC composite columns was established through the mechanical derivation, which can be used to design and evaluate the performance of anchorage zones in steel-RAC composite structures.

• Computers and Concrete
• /
• v.4 no.5
• /
• pp.377-402
• /
• 2007

The paper presents quasi-static plane strain FE-simulations of strain localization in reinforced concrete beams without stirrups. The material was modeled with two different isotropic continuum crack models: an elasto-plastic and a damage one. In case of elasto-plasticity, linear Drucker-Prager criterion with a non-associated flow rule was defined in the compressive regime and a Rankine criterion with an associated flow rule was adopted in the tensile regime. In the case of a damage model, the degradation of the material due to micro-cracking was described with a single scalar damage parameter. To ensure the mesh-independence and to capture size effects, both criteria were enhanced in a softening regime by nonlocal terms. Thus, a characteristic length of micro-structure was included. The effect of a characteristic length, reinforcement ratio, bond-slip stiffness, fracture energy and beam size on strain localization was investigated. The numerical results with reinforced concrete beams were quantitatively compared with corresponding laboratory tests by Walraven (1978).