• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.330-339
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• 1991

The acid properties of $V_2O_5-TiO_2/SiO_2$ catalysts and the partial oxidation of o-xylene into phthalic anhydride had been investigated in order to relate the acid property of catalyst to the catalytic activity. $V_2O_5$ had both weak (V=O) and strong (V-O-V) acid sites which gave pyridine desorption peaks at $230^{\circ}C$ and $300^{\circ}C$, respectively, and the amount of weak acid sites at $230^{\circ}C$ decreased with the increase of calcination temperature. On the other hand, the amount of weak acid sites increased considerably by increasing the amount of $TiO_2$ to the $V_2O_5-TiO_2/SiO_5$, and the maximum value was shown at 20 and higher mole % of $TiO_2$ with respect to $SiO_2$. In the oxidation of o-xylene, $V_2O_5-TiO_2/SiO_2$ enhandced more the total conversion and the selectivity to phthalic anhydride than $V_2O_5/SiO_2$, and the higher $TiO_2$ ratio to $V_2O_5$ increased the total conversion but could not change the selectivity to phthalic anhydride. Weak acid sites (V=O) led o-xylene to partial oxidation producing phthalic anhydride by adsorbing o-xylene weakly, while acid sites (V-O-V) led it to total oxidation producing CO and $CO_2$ by adsorbing it strongly.

• Journal of Chest Surgery
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• v.35 no.1
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• pp.48-51
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• 2002

The conversion of failing Fontan circuit to total cavopulmonary connection(TCPC) is recommended as a therapeutic option in patients with late Fontan complications such as atrial arrhythmia, atrial enlargement, pulmonary venous obstruction, and ventricular dysfunction. Combined TCPC with extracardiac conduit and cryoablation of arrhythmia circuit is preferred for treatment of failing Fontan coulection with atrial lachyarrhythrnia. We report a case of conversion of atriopulmonary connection to extracardiac conduit Fontan and cryoablation of atrial arrhythmia circuit in a patient with tricuspid atresia, who also had ectopic atrial tachycardia, right atrial thrombi, pulmonary venous obstruction, and ventricular dysfunction. This patient and the parents were Jehovah's Witnesses; therefore, the patient underwent the procedure without blood transfusion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.305-314
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• 2018

The steel-plate concrete composite beam is composed of a steel plate, concrete and a shear connector to combine the two inhomogeneous materials. In general, the steel plate is assembled by welding an existing composite beam. In this study, a new steel-plate concrete composite (SPCC) beam was developed to reduce the size of the shear connector and improve its workability. The SPCC beam was composed of folded steel plates and concrete, without any shear connector. The folded steel plate was assembled with high strength bolts instead of welding. To improve the workability in field construction, a hat-shaped cap was attached in the junction with the slab. Monotonic two-point load testing was conducted under displacement control mode. The flexural strength of the SPCC beam specimen was calculated to be 76% of that of the complete composite beam by using the plastic stress distribution method and strain compatibility method. The cap acted as the stud and accessory. The synthesis rate could be increased by controlling the gap of the cap, and the bending performance could be evaluated by using the strain fitting method considering the synthesis rate of the SPCC beam.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.337-347
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• 2011

In this study, seismic resistance of concrete encased U-shaped steel beam-to-steel H-shaped column connections was evaluated. Three specimens of the beam-to-column connection were tested under cyclic loading. The composite beam was integrated with concrete slab using studs. Re-bars for negative moment were placed in the slab. The primary test parameter was the details of the connections, which are strengthening and weakening strategies for the beam end and the degree of composite action. The depth of the composite beams was 600mm including the slab thickness. The steel beam and the re-bars in the slab were weld-connected to the steel column. For the strengthening strategy, cover plates were weld-connected to the bottom and top flanges of the steel beam. For the weakening strategy, a void using styrofoam box was located inside the core concrete at the potential plastic hinge zone. The test results showed that the fully composite specimens exhibited good strength, deformation, and energy dissipation capacities. The deformation capacity of the beam exceeded 4% rotation angle, which is the requirement for the Special Moment Frame.

• Journal of Korean Society of Steel Construction
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• v.23 no.5
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• pp.535-546
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• 2011

In this paper, semi-rigid elasto-plastic post-buckling analysis of a space frame was performed using various explicit arc-length methods. Various explicit arc-length methodsand a large-deformation and small-strain elasto-plastic 3D space frame element with semi-rigid connections and plastic hinges were developed. This element can be appliedto both explicit and implicit numerical algorithms. In this study, the Dynamic Relaxation method was adopted in the predictor and corrector processesto formulate an explicit arc-length algorithm. The developed "explicit-predictor" or "explicit-corrector" were used in the elasto-plastic post-buckling analysis. The Eulerian equations for a beam-column with finite rotation, which considers the bowing effects, were adopted for the elastic system and extended to theinelastic system with a plastic hinge concept. The derived tangent stiffness matrix was asymmetrical due to the finite rotation. The joint connection elements were introduced for semi-rigidity using a static condensation technique. Semi-rigid elasto-plastic post-buckling analyses were carried out to demonstrate the potential of the developed explicit arc-length method and advanced space frame element in terms of accuracy and efficiency.

• Journal of Korean Society of Steel Construction
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• v.22 no.2
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• pp.129-137
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• 2010

In this study, a five-story steel frame was designed in accordance with KBC2005 to evaluate the effect of the beam-column connection on the structural behavior. The connections were designed as a fully rigid connection and as a semirigid connection. A fiber model was utilized to describe the moment-curvature relationship of the steel beam and column, and a three-parameter power model was adopted for the moment-rotation angle of the semirigid connection. To evaluate the effects of higher modes on structural behavior, the structure was subjected to a KBC2005-equivalent lateral load and lateral loads considering higher modes. The structure was idealized as a separate 2D frame and as a connected 2D frame. The pushover analysis of 2D frames for the lateral load yielded the top displacement-base shear force, design coefficients such as overstrength factor, ductility ratio, and response modification coefficient, demanded ductility ratio for the semirigid connection,and distribution of plastic hinges. The sample structure showed a greater response modification coefficient than KBC2005, the higher modes were found to have few effects on the coefficient, and the lateral load of KBC2005 was found to be conservative. The TSD connection was estimated to secure economy and safety in the sample structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.126-136
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• 2018

A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.147-157
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• 2018

The basis of capacity design has been explicitly or implicitly regulated in most bridge design specifications. It is to guarantee ductile failure of entire bridge system by preventing brittle failure of pier members and any other structural members until the columns provides fully enough plastic rotation capacity. Brittle shear is regarded as a mode of failure that should be avoided in reinforced concrete bridge pier design. To provide ductility behavior of column, the one of important factors is that flexural hinge of column must be detailed to ensure adequate and dependable shear strength and deformation capacity. Eight small scale circular reinforced concrete columns were tested under cyclic lateral load with 4.5 aspect ratio. The test variables are longitudinal steel ratio, transverse steel ratio, and axial load ratio. Eight flexurally dominated columns were tested. In all specimens, initial flexural-shear cracks occurred at 1.5% drift ratio. The multiple flexural-shear crack width and length gradually increased until the final stage. The angles of the major inclined cracks measured from the vertical column axis ranged between 42 and 48 degrees. In particular, this study focused on assessing transverse reinforcement contribution to the column shear strength. Transverse reinforcement contribution measured during test. Each three components of transverse reinforcement contribution, axial force contribution and concrete contribution were investigated and compared. It was assessed that the concrete stresses of all specimen were larger than stress limit of Korea Bridge Design Specifications.

• Journal of Veterinary Clinics
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• v.27 no.5
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• pp.600-604
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• 2010

A ten-year-old female mongrel dog was presented to Veterinary Medical Center, Chungbuk National University with the signs of anorexia, weakness, and hemoglobinuria. Patient had been diagnosed as dirofilariasis based on heartworm antigen test and treated with adulticide (melarsomine) at local hospital one day before admission. On laboratory examinations, there were hypochromic and microcytic regenerative anemia, thrombocytopenia, moderate neutrophilia, and increase ALT, AST, and ALP. Radiographic exam showed main pulmonary artery bulging, pulmonary infiltration and hypervascularity, reduced abdominal serosal detail and mild hepatomegaly. Abdominal ultrasonographic exam showed mild peritoneal effusion and large hyperechoic thrombi at trifurcation of the porta hepatica and the splenic vein. In addition, intraluminal low density area and intravascular filling defect were confirmed on contrast enhanced CT scanning at the same anatomic locations. Patient was treated with anticoagulant and thrombolytic therapy. On day 42 after treatment, complete resolution of thrombi was confirmed via ultrasonography and improvement of clinical signs was observed.

• Journal of the Korean Geotechnical Society
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• v.21 no.7
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• pp.55-62
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• 2005

The use of the bearing capacity equation is subjected to several uncertainties. In this study, estimation of the bearing capacity of footings based on the cone resistance q$_{c}$ is investigated. Non-linear finite element analyses based on a state-dependent stress-strain model were performed to obtain the load-settlement responses of axially loaded circular footings. Various soil and footing conditions, including different relative densities, depths of embedment, and footing diameters were considered in the analyses. Based on the finite element results, load-settlement curves were obtained and used to determine the unit limit bearing capacity in terms of the cone resistance q$_{c}$ for footings subjected to surcharge. Values of the unit bearing capacity for different embedment depths were in a narrow range, while considerable variation was observed with relative density D$_{R}$. It was observed that the unit limit bearing capacity normalized with respect to q$_{c}$ decreases as D$_{R}$ increases for a given surcharge.