• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.5
• /
• pp.143-151
• /
• 2008

In this paper, the optimum design of plane steel frames using second-order inelastic analysis and section increment method is presented. Since the second-order inelastic analysis accounts for geometric and material nonlinearities of the whole system as well as its component members, the design method based on second-order inelastic analysis does not require separate member capacity checks after analysis. A section increment method proposed by this paper is used as optimization technique. The weight of structures is treated as the objective function. The constraint functions are defined by load-carrying capacities, deflections, inter-story drifts, and ductility requirement. The effectiveness of the proposed method are verified by comparing the results of the proposed method with those of other method.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.2 s.54
• /
• pp.153-164
• /
• 2009

In this paper, a method of increasing in load-carrying capacity is shown in two-span steel-concrete composite bridges strengthened by external tendons. An analytic expression for the increment of tendon force under external loads is derived using virtual work method for straight external tendons and a new rating factor equation is proposed. Considering the initial tendon force and its increment under external loads, an analytic procedure has been developed to calculate the number of tendons and the initial tendon force from the proposed rating factor equation. This method is used to verify a validity and rationality for an existing two-span composite steel-concrete bridge.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.8 no.1
• /
• pp.159-164
• /
• 1988

The directions of the principal strain increment, stress, and stress increment during rotation of the principal stress axes at any stress level was studied for $K_0$-consolidated clay using torsion shear apparatus with individual control of the vertical stress, the confining pressure, and the shear stress on hollow cylinder specimens under undrained and drained condition. The torsion shear tests were performed according to predetermined stress-paths, which were chosen to cover over the full range of rotation of principal stress axes. The test results indicated that the strain increment vectors at failure coincided with the stress vectors. That is, the direction of strain increment coincided with the direction of stress increment at small stress levels and with the direction of stress at higher stress levels, which indicated that the behavior of clay was transfered from elastic to plastic as the stress level was increased. The applicability of the elastoplastic theory for modeling of the behavior of clay during rotation of the principal stress axes was given.

• Journal of Preventive Medicine and Public Health
• /
• v.44 no.3
• /
• pp.111-117
• /
• 2011

Objectives: This study measured the impact of shifts in maternal age and parity on the increase in the low birth weight (LBW) rate in Korea. Methods: We obtained raw data for all 6 397 945 live births registered at the Korea National Statistical Office between 1995 and 2005. We calculated the proportion of increment in the LBW rate due to changes in the distribution of maternal age and parity (AP-dis) and the proportion due to changes in the age- and parity-specific LBW rate (AP-spe). Results: The LBW rate increased from 3.02% in 1995 to 4.28% in 2005. The multiple birth rate increased from 1.32% to 2.19% during the same period. Of the 1.26% points increment in the LBW rate, 0.64% points occurred among singleton births and 0.62% points occurred among multiple births. Changes in the AP-dis accounted for 50% of the increase in the LBW rate among singleton births, but did not contribute to the increase in the LBW rate among multiple births. The remainder of the total increment in the LBW rate was explained by the increase in the AP-spe. Conclusions: This study demonstrated that shifts in maternal age and parity among singleton births and increased multiple births were important contributors to the increment in the LBW rate. This study also revealed that the increase in the AP-spe was an equally important contributor as the shifts in maternal age and parity to the increment in the LBW rate among singleton births and was a major contributor among multiple births.

• The Korean Journal of Pharmacology
• /
• v.12 no.2 s.20
• /
• pp.21-32
• /
• 1976

The influence of Panax ginseng and Acanthopanax on the metabolism of hens are studied experimentally. The hens are fed with three dose levels of ethanol extract of Panax ginseng and Acanthopanax for 24 months and for comparing, there are control hens and young control hens. The results are as follows. 1. Hemoglobin, hematocrit and erythrocyte sedimentation rate values of hens fed with Panax ginseng and Acanthopanax are not significantly. different from control group. There is tendency of decreasing of erythrocyte sedimentation rate with aging. 2. The serum total lipid values of hens fed with Panax ginseng and Acanthopanax have tendency of increment compared with control group, especially in large dose treated hens of Panax ginseng and it is statistically significant. The serum cholesterol levels of all treated hens seem to be increased without significance statistically. Serum triglyceride level is higher in young hens compared with aged, and Panax ginseng and Acanthopanax treated hens reveal much higher values than control hens. So the increment of triglyceride levels in the Panax ginseng and Acanthopanax treated hens may be mainly contribute to increment of total lipid content. 3. Long-term administration of Panax ginseng and Acanthopanax seem to increase total serum protein content. Such increment seem to be due to the increment of globulin, especially gamma globulin, which is statistically significant in the large dose group of Acanthopanax. There are no differences of serum albumin levels of all the groups. 4. The blood glucose level and the glycogen content of liver and muscle have no difference among all the experimental groups. To summarize the results, the effects of Panax ginseng and Acanthopanax on the metabolism of hens have similarity in the majority of data of this experiment, and seem to be mainly influence to lipid and protein metabolisms by increasing serum triglyceride and globulin, especially gamma globulin.

• Journal of Korean Port Research
• /
• v.14 no.3
• /
• pp.331-340
• /
• 2000

For the rational and economic design of the structural elements of ships which is built using welding, the ultimate strength analyses of the plates having initial imperfections, such as welding residual stresses and strains, are needful. The welding deformation usually relied on approximative equations or based on expert's experience. But in this paper, for the thermal elasto-plastic analysis of plates, the finite element analysis was performed, based on initial strain method. In formulating the incremental analysis, unbalanced force terns were included. In the plastic domain during the incremental process, the 2nd order terns stress increment and yield stress increment were considered, so that time increment could be controlled for a more stable solution. The ultimate strength analysis program of the plates having initial imperfections was made. The ultimate strength analysis was carried out based on the results of the welding deformations of this paper. In the ultimate strength analysis the Rayleigh-Ritz method based on the minimum potential theory was used.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.773-777
• /
• 1995

This thesis attempt to explore the shape of stress wave propagation of 3-dimensional stress field which is made in the process of time increment. A finite element code about 3-dimensional stress wave propagation is developed for investigating the changing shape of the fracture by the impact load. The Finite Element Code, which is the solution for the 3-dimensional stress wave analysis, based on Galerkins and Newmark- .betha. method at time increment step. The tensile stress and compressive stress become larger with the order of the middle, the upper and the opposite layers when the impact load is applied. In a while the shear stress become larger according to the order of the upper, the middle and the opposite layers when impact load applied.

• Tribology and Lubricants
• /
• v.14 no.4
• /
• pp.7-14
• /
• 1998

A correlation between the low-cycle fatigue life and the scuffing-failure life is demonstrated using the plastic strain increment in boundary lubricated sliding. Loadings proportional to hardness with three different lubricated conditions were used to evaluate the plastic strain increments. As the results of scuffing tests using vacuum pump oils in nitrogen gas, plastic strain increment shows 0.0062, and in the mineral oils and commercial engine oils in air, plastic strain increments show 0.0042 and 0.00092. Those are very useful to describe quantitatively the real lubricated sliding conditions, and are very effective to find the relation between the low-cycle fatigue life and the scuffing-failure life.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.51 no.6
• /
• pp.83-90
• /
• 2009

This study was carried out to evaluate the vertical stress properties in sandy soil according to changes of loading type in soil bin compacted three layers. The following conclusions and comparisons have been made based on careful analysis from theoretical and experimental methods. : When sandy soil subjected to cycle-loading, compression of foundation and diffusion of vertical stress increment(${\Delta}{\sigma}_2$) were influenced by magnitude of loading plate. When sandy soil subjected to reloading after removing of pre-loading, the distribution of ${\Delta}{\sigma}_2$ depth at one time of loading plate width was different from its distribution at more deep point cause of load hysteresis, so in case of design of structure, the effect of ${\Delta}{\sigma}_2$ as depth must be considered. The increment of vertical stress will be different as loading condition and foundation depth, the loading condition must be considered in case of structure design.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.199-202
• /
• 2003

A study for permeability and erosion characteristics of short fiber reinforced soils was performed. As mixing ratio increases from 0 to 1.0% permeability of short fiber reinforced soils increased but, maximum increment ratio($k_{1.0%}/k_{0%}$) was 8.47. As a result of permeability test with 19, 38 and 60mm fiber reinforced soils, there were no difference in fiber length. Void ratio increased with increment of mixing ratio and decrease of compaction energy and as a result of plotting permeability and void ratio, log k increased linearly by void ratio. As a result of erosion test, soil erosion was decreased sharply by increase of fiber mixing ratio up to 1.0%. Despite increase of soil erosion by slope angle, the increment ratio was decreased by mixing ratio.