• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.595-604
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• 2000

Web openings of large beams provide space for wiring, piping, and duct work to provide for proper drainage, pipes and duct must be slightly sloped with the attendant result that all web openings can not be centered on the centroidal axes of the beams. Test specimens are made for opening-depth to beam-depth ratio of 0.5 and for eccentricities of the opening center line of 10% from middepth of the beam because of the proximity of the opening edge to the flange. In this paper, available test results and theories relating to the strength of composite beams having eccentric rectangular openings are surveyed and experiments were carried out to examine the structural behaviors. In all the tests in this paper good agreement is demonstrated with maximum loads measured in tests, and observed failure modes Furthermore, compared with analytical values and experimental values of interaction diagram between moment and shear capacity were safed as it is scattered with outer part of the analytical values.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.3
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• pp.82-94
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• 1988

A growing attention has been paid to the optimum design of structures in recent years. Most studies on the optimum design of reinforced concrete structures has been mainly focussed to the design of structural members such as beams, slabs and columns, and there exist few studies that deal with the optimum design of large-scale concrete shell structures. The purpose of the present investigation is, therefore, to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir. The major design variables are the dimensions and steel areas of each member of structures. The construction cost which is compo8ed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of strength design method. The results obtained are summarized as follows 1. The efficient optimlzation algorithrns which can execute the automatic optimum design of reinforced concrete intake tower based on the strength design method were developed. 2. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optimization algorithms developed in this study seem to be efficient and stable. 3. When using the strength design method, the construction cost could be saved about 9% compared with working stress design method. Therefore, the reliability of algorithm was proved. 4. The difference in construction cost between the optimum designs with substructures and with entire structure was found to be small and thus the optimum design with substructures may conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the 'bending moment constraint for slab, the minimum longitudinal steel ratio constraint for tower body and the shearing force, bending moment and maximum eccentricity constraints for footing, respectively. 6. The computer program developed in the present study can be effectively used even by an uneiperienced designer for the optimum design of reinforced concrete intake-tower on the basis of strength design method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.26-34
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• 2015

The angle of attack of a cambered otter board in a bottom trawl was estimated using a three-dimensional semi-analytic treatment of a towing cable (warp) system that was applied to the field experiments of a bottom trawl obtained by the Scanmar system. The equilibrium condition of the horizontal component and vertical component of forces was used to the three forces acting on the otter board in the horizontal plane. Those forces were the force on the warp at the bracket, hydrodynamic lift and drag forces on the otter board and the force on the hand rope attached just behind the otter board. Also the equilibrium of moment about the front edge of the otter board was used to find out the angle of attack of the cambered otter board. When the warp length was 120m and 180m long and the towing speed was between 1.23 and 1.90 m/s, the estimated angle of attack of the cambered otter board was ranged between $26.1^{\circ}$ and $29.6^{\circ}$, respectively, though the maximum lift force was at the angle of attack $22.6^{\circ}$. The angle of attack of the otter board was tended to increase weakly with the longer length of warp (180 m) at the same towing speed in the experiment.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.3-44
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• 1999

This paper discusses the lateral behavior of single and group piles in homogeneous and non-homogeneous(two layered) soil. In the single pile, the model tests were conducted to investigate the effects on ratio of lower layer height to embedded pile length, ratio of soil modules of upper layer to lower layer, boundary rendition of pile head and tip, embedded pile length, pile construction condition, ground condition with saturate and moisture state in Nak-Dong river sand. Also, in the group pile, the model tests were to investigate the effects on spacing-to-diameter ratio of pile, pile array, ratio of pile spacing, boundary condition of pile head and tip, eccentric load and ground condition. The maximum bending moment and deflection induced in active piles were found to be highly dependent on the relative density, pile construction condition, boundary condition of pile head and tip. Based on the results obtained, it was found that the decrease of lateral bearing capacity in saturated sand was in the range of 31% - 53% as compared with the case of dry sand. Also, in the group pile, a spacing-to-diameter of 6.0 seems to be large enough to eliminate the group effect for the case of relative density of 61.8%, and 32.8%, and then each pile in such a case behaves essentially the same as a single pile. In this study, the program is developed by using the modified Chang method which used p - y method and the exact solution of governing equation of pile and it can be used to calculate the deflection, bending moment and soil reaction with FDM in non-homogeneous soil. In comparing the modified Chang method with field test results, the predict results shows better agreement with measured results in field tests.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.457-468
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• 2006

An experimental study was performed to investigate the maximum energy dissipation and the ductility capacity of shear-dominated steel plate walls with thin web plates. Three specimens of three-story plate walls with thin web plates were tested. The parameters for the test specimens were the aspect ratio of the web plate and the shear strength of the column. A concentrically braced frame and a moment-resisting frme were a also tested for comparison. The steel plate walls exhibited much better ductility and energy dissipation capacity than the concentrically braced frame and the moment-resisting frame. The results showed that unlike other structural systems, the sh as well as strength, and can therefore be used as an effective earthquake-resisting system. A method of predicting the energy dissipation capacity of a steel plate wall was proposed.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.647-657
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• 2012

Although nuclear power plant piping system is designed conforming to design specifications, the piping systems are deteriorated with increase in service life. In this study, monotonic and cyclic loading tests were carried out on TP316 stainless steel pipe specimens, and the effect of local wall thinning and cracking on failure behavior was investigated. In the tests, 0%, 35% and 75% wall thinning and cracking of initial thickness were artificially introduced to inside elbow and straight pipe specimens, and internal pressures of 20MPa were applied to simulate real operation condition. From the test results, the effect of local wall thinning and cracking on failure mode, ultimate load, number of cycle and strain energy was presented, and maximum bending moment was compared with allowable bending moment calculated by ASME code.

• Computers and Concrete
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• v.14 no.2
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• pp.127-143
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• 2014

LOCA (Loss Of Coolant Accident) is one of the most important utmost accidents for Prestressed Concrete Containment Vessel (PCCV) due to its coupled effect of high temperature and inner pressure. In this paper, heat conduction analysis is used to obtain the LOCA temperature distribution of PCCV. Then the elastic internal force of PCCV under LOCA temperature is analyzed by using both simplified theoretical method and FEM (finite element methods) method. Considering the coupled effect of LOCA temperature, a nonlinear elasto-plasitic analysis is conducted for PCCV under utmost internal pressure considering three failure criteria. Results show that the LOCA temperature distribution is strongly nonlinear along the shell thickness at the early time; the moment result of simplified analysis is well coincident with the one of numerical analysis at weak constraint area; while in the strong constrained area, the value of moments and membrane forces fluctuate dramatically; the simplified and numerical analysis both show that the maximum moment occurs at 6hrs after LOCA.; the strain of PCCV under LOCA temperature is larger than the one of no temperature under elasto-plastic analysis; the LOCA temperature of 6hrs has the greatest influence on the ultimate bearing capacity with 8.43% decrease for failure criteria 1 and 2.65% decrease for failure criteria 3.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.4
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• pp.45-57
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• 1998

This study was conducted to derive optimal design floods by Generalized Extreme Value (GEV) distribution for the annual maximum series at ten watersheds along Han, Nagdong, Geum, Yeongsan and Seomjin river systems. Adequacy for the analysis of flood data used in this study was established by the tests of Independence, Homogeneity, detection of Outliers. L-coefficient of variation, L-skewness and L-kurtosis were calculated by L-moment ratio respectively. Parameters were estimated by the Methods of Moments and L-Moments. Design floods obtained by Methods of Moments and L-Moments using different methods for plotting positions in GEV distribution were compared by the Relative Mean Errors(RME) and Relative Absolute Errors(RAE). The results were analyzed and summarized as follows. 1. Adequacy for the analysis of flood data was acknowledged by the tests of Independence, Homogeneity and detection of Outliers. 2. GEV distribution used in this study was found to be more suitable one than Pearson type 3 distribution by the goodness of fit test using Kolmogorov-Smirnov test and L-Moment ratios diagram in the applied watersheds. 3. Parameters for GEV distribution were estimated using Methods of Moments and L-Moments. 4. Design floods were calculated by Methods of Moments and L-Moments in GEV distribution. 5. It was found that design floods derived by the method of L-Moments using Weibull plotting position formula in GEV distribution are much closer to those of the observed data in comparison with those obtained by method of moments using different formulas for plotting positions from the viewpoint of Relative Mean Errors and Relative Absolute Errors.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.530-538
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• 2007

Magnetocardiography (MCG) is a device to measure the magnetic field from the heart. It is a noninvasive device and takes only few minutes to record magnetocardiogram from a subject. In this study, we compared the difference of MCG data recorded from 56 normal subjects in early twenties (28 males and 28 females, mean $age=21.0{\pm}1.6$ years) and 36 elderly subjects (20 males and 16 females, mean $age=61.9{\pm}6.9$ years) for the analysis of the age and gender difference. A total of 24 parameters used in the analysis were derived from QRS complex, R-wave, T-wave, and ST-T period. As a result, seven parameters including maximum current angle and map angle showed the significant difference (p<0.01 and p<0.05, respectively) between young males and young females. Significant difference (p<0.05) between elderly males and elderly females was found from a parameter, pole distance at T-wave peak. In the comparison of age difference, seven parameters regarding current moment, pole distance, and dynamics showed the significant difference between young and elderly males. Eight parameters also showed significant difference (p<0.05) between two younger and elderly female groups. Results showed that parameters regarding current moment, pole distance, and dynamics might be changed when people get older. In conclusion, gender and age difference should be considered when MCG data are analyzed for certain parameters.

• Journal of the Korean Geotechnical Society
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• v.27 no.5
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• pp.33-43
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• 2011

In this study, simplified analysis (discrete analysis of column and pile) of pile bent structures was performed on the basis of the equivalent base spring model. And the minimum reinforcement ratio in pile bent structures was evaluated by taking into account various factors. To obtain the detailed information, simplified analysis was performed for column-pile interactions and the behavior of a column-pile was estimated and highlighted. Based on this study, it is shown that previous design method based on virtual fixed point theory cannot adequately predict the physical behavior of pile bent structures. It is found that the maximum bending moment is located within craking moment of the pile when material non-linearity is considered. It is also found that the minimum reinforcement ratio (=0.4%) is appropriately applicable for the optimal design of pile bent structure under ultimate lateral loading.