• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.965-973
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• 2001

It is well established that arteries are subjected to residual stress. Due to the effect of residual stress, the arteries open to a horse-shoe shape when a longitudinal cut is made on an excised arterial segment. Previously, the residual stress has been quantified by the opening angle of the horse-shoe shape. We have employed a finite element analysis of the open arterial segment to restore the same to the original cylindrical shape and computed the circumferential strain as well as the stress distribution in the wall. In this study, the stress distribution in the femoral arteries of miniswine was computed with and without the residual stress for a range of transmural pressures. Our analysis showed that the residual stress has the effect of redistribution of the circumferential stresses between the intima and the adventitia under physiological loading. The redistribution of the stress with the inclusion of residual stress may be important in the studies on effect of wall stresses on the endothelial and vascular smooth muscle cells.

• Korean Journal of Poultry Science
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• v.26 no.3
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• pp.171-177
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• 1999

This study was conducted for the histological observation of the infundibulum of the oviduct of the laying Korean native pheasants. The results are as follows : 1. The infundibular wall is composed of the epithelium, lamina propria, muscle layer(inner circular and outer longitudinal muscle), and serosa. The funnel lip is divided into the inner, and outer lip of the epithelium and muscle layer. 2. The epithelium of the funnel lip and most region of the cranial part of the funnel are composed of ciliated columnar cells. In the surface and lateral part of the folds, ciliated cells and non-ciliated secretory cells tend to alternate in the epithelium of the caudal funnel and the necks, but are also found in groups of the simple cuboidal epithelium at the bases of the grooves between the ridges and tubular glands found in the subepithelium. 3. The secretory material of the non-ciliated secretory cills contains PAS-positive and alcian blue-positive granules, and these materials show purple colour in the basic fuchsin-methylene blue stain. 4. The cells of the glandular groove and tubular gland of the neck portion of the oviduct mostly show weak PAS-positive, and alcian blue stain negative reaction. The tubular gland cells of the infndibulum contain pink of purple colour granules, and without reaction in the anterior neck portion of the infundibulum in basic fuchsin and methylene blue stain.

• Steel and Composite Structures
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• v.1 no.3
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• pp.295-312
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• 2001

The purpose of this paper is to propose a new type of steel reinforced concrete (SRC) beam-column joints and to examine the structural performance of the proposed joints, which simplify the construction procedure of steel fabrication, welding works, concrete casting and joint strengthening. In the proposed beam-column joints, the steel element of columns forms continuously built-in crossing of H-sections (${\Box}$), with adjacent flanges of column being connected by horizontal stiffeners in a joint at the level of the beam flanges. In addition, simplified lateral reinforcement (${\Box}$) is adopted in a joint to confine the longitudinal reinforcing bars in columns. Experimental and analytical studies have been carried out to estimate the structural performance of the proposed joints. Twelve cruciform specimens and seven SRC beam-column subassemblage specimens were prepared and tested. The following can be concluded from this study: (1) SRC subassemblages with the proposed beam-column joints show adequate seismic performances which are superior to the demand of the current code; (2) The yield and ultimate strength capacities of the beam-to-column connections can be estimated by analysis based on the yield line theory; (3) The skeleton curves and the ultimate shear capacities of the beam-column joint panel are predicted with a fair degree of accuracy by considering a simple stress transfer mechanism.

• Steel and Composite Structures
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• v.27 no.3
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• pp.355-370
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• 2018

In steel-concrete composite beams, longitudinal shear forces are transferred across steel flange-concrete slab interface by means of shear connectors. The connector behavior is highly non-linear and involves several complex mechanisms. The design resistance and stiffness of composite beams depends on the shear connection behavior and the accuracy in the connector resistance prediction is essential. However determining the stud shear resistance is not an easy process: analytical methods do not give an adequate response to this problem and it is therefore necessary to use experimental methods. This paper present a summary of the main procedures to predict the resistance of the stud shear connectors embedded in solid slab, and stud shear connectors in composite slab using profiled steel sheeting with rib perpendicular to steel beam. A large number of experimental studies on the behavior of stud shear connectors and reported in the literature are also summarized. A comparison of the stud shear resistance prediction using six reference codes (AISC, AASHTO, Eurocode-4, GB50017, JSCE and AS2327.1) and other procedures reported in the literature against experimental results is presented. From this exercise, it is concluded that there are still inaccuracies in the prediction of stud shear resistance in all analysed procedures and that improvements are needed.

• Geomechanics and Engineering
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• v.23 no.5
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• pp.405-418
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• 2020

Deep excavation may have impact on the adjacent tunnels. It is obvious that the excavation will adversely affect and even damage the existing tunnels if the induced deformation exceeds the capacity of tunnel structures. It hence creates a high necessity to predict tunnel displacement induced by nearby excavation to ensure the safety of tunnel. In this paper, a simplified method to evaluate the heave of the underlying tunnel induced by adjacent excavation is presented and verified by field measurement results. In the proposed model, the tunnel is represented by a series of short beams connected by tensile springs, compressional springs and shear springs, so that the rotational effect and shearing effect of the joints between lining rings can be captured. The proposed method is compared with the previous modelling methods (e.g., Euler-Bernoulli beam, a series of short beams connected only by shear springs) based on a field measured longitudinal deformation of subway tunnels. Results of these case studies show a reasonable agreement between the predictions and observations.

• Computational Structural Engineering : An International Journal
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• v.1 no.1
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• pp.1-9
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• 2001

Collapse behavior of Mission-Gothic Undercrossing under Northridge earthquake is studied by performing nonlinear time-history analysis and three-dimensional nonlinear finite element method for flared columns. Bridge structural model is characterized as three-dimensional with consideration of columns, superstructures, and abutment conditions. Three components of ground motion, corresponding to bridge's longitudinal, transverse, and vertical direction and their combinations are used to investigate bridge collapse. Studies indicate that bridge collapse is dominantly caused by transverse ground motion and the consideration of three-dimensional ground motion leads to a more accurate assessment. Failure mechanism of flared columns is analyzed applying nonlinear finite element method. Reduction of column capacity is observed due to orientation of flare. Further investigation demonstrates that the effects of flare play an important role in predicting of bridge failure mechanism. Suggestions are offered to improve the performance of bridges during severe earthquake.

• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.237-242
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• 2020

This paper deals with relative position estimation using a Kalman filter (KF) based on inertial sensors that have been widely used in various biomechanics-related outdoor applications. In previous studies, the relative position is determined using relative orientation and predetermined segment-to-joint (S2J) vectors, which are assumed to be constant. However, because body segments are influenced by soft tissue artifacts (STAs), including the deformation and sliding of the skin over the underlying bone structures, they are not constant, resulting in significant errors during relative position estimation. In this study, relative position estimation was performed using a KF, where the S2J vectors were adopted as time-varying states. The joint constraint and the variations of the S2J vectors were used to develop a measurement model of the proposed KF. Accordingly, the covariance matrix corresponding to the variations of the S2J vectors continuously changed within the ranges of the STA-causing flexion angles. The experimental results of the knee flexion tests showed that the proposed KF decreased the estimation errors in the longitudinal and lateral directions by 8.86 and 17.89 mm, respectively, compared with a conventional approach based on the application of constant S2J vectors.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.23 no.1
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• pp.3-7
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• 2012

Objectives : The early onset of mood symptoms in bipolar disorder has been associated with poor outcomes in many studies. However, aspects of the clinical course of bipolar disorder in children and adolescents are controversial. The goal of this article is to review the clinical characteristics and longitudinal course of children and adolescents with bipolar disorders. Methods : Searches were conducted in MedLine, PsycINFO, KISS, and RISS using the terms phenomenology, clinical course, outcome, BPD, pediatric, children and adolescents. Twenty-one reports were selected : either original articles reporting symptoms and clinical characteristics of subjects (ages 5-18 years), or published articles in reviewed journals about bipolar disorder in children and adolescents. Results : Approximately 70% of subjects with bipolar disorder recovered from their index episode, and 50% had at least 1 syndromal recurrence, particularly depressive episodes. For 60% of the follow-up time, subjects had syndromal or subsyndromal symptoms with numerous changes in symptoms and shifts of polarity. Approximately 20% of BP-II subjects converted BP-I. Conclusion : Bipolar disorders in children and adolescents are characterized by episodic illness with subsyndromal and syndromal episodes with mainly depressive and mixed symptoms and rapid mood changes. Extensive follow-up time is needed to evaluate the continuity of bipolar disorder symptoms from childhood to adulthood.

• Korean Medical Education Review
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• v.16 no.2
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• pp.77-87
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• 2014

The purpose of this study was to investigate the influence of demographic data, academic demand, perfectionism, and academic failure tolerance on academic burnout of medical and graduate students at Yeungnam University. A mixed method study was conducted. Fourteen students participated in a focus group interview and 302 students, including 151 medical students and 151 graduate students, completed a survey, which addressed the factors of academic burnout, academic demand, perfectionism, and academic failure tolerance. There were significant differences in the academic burnout by age and year in school. The 2nd year medical & graduate students experienced significantly higher academic burnout than the other students. Multiple regression analysis revealed that academic burnout of medical and graduate students was significantly affected by academic demand (p<0.001), self-oriented and socially-prescribed perfectionism (p<0.001, p<0.01), and feeling and behavior, which were sub-factors of academic failure tolerance (p<0.05, p<0.01). It is suggested that comparative studies with other student groups, a longitudinal study of medical and graduate students, and a prospective study of coping styles and methods of preventing academic burnout need to be conducted.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.97-100
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• 2008

Various flyers in nature have attracted great interests with a recent need for developing versatile and small-size flight vehicles. In the present study, we focus on the flying fish which has been observed to glide a long distance just above a seawater surface. Since previous studies have depended on the field observation or measurement of the physical parameters only, quantitative data of the flying fish flight has not been provided so far. Therefore, we evaluate the wing performance of the flying fish in gliding flight by directly measuring the lift, drag and pitching moment on real flying fish models (Cypselurus hiraii) in a wind tunnel. In addition, we investigate the roles of wing morphology like the enlarged pectoral and pelvic fins, and lateral dihedral angle of pectoral fins. With both the pectoral and pelvic fins spread, the lift-to-drag ratio is larger and the longitudinal static stability is enhanced than those with the pelvic fins folded. From the glide polar, we find that the wing performance of flying fish is equivalent to those of medium-size birds like the petrel, hawk and wood duck. Finally, we examine the effect of water surface underneath the flying fish and find that the water surface reduces the drag and increases the lift-to-drag ratio.