• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.3
• /
• pp.459-465
• /
• 2012

This study was conducted to obtain investigated characteristic factors which has an influence on nitrous oxide ($N_2O$) emissions related to the environment change of nitrogen application level, rainfall and temperature. It was done by the carrot cultivation at black volcanic ashes soil in the experimental field of Jeju Special Self-governing Province Agricultural Research and Extension Services from 2010 to 2011. During the carrot cultivation period, the more amount of nitrogen fertilizer applied, the more amount of $N_2O$ emissions were released. Generally $N_2O$ emissions were so deeply released to climate as that in the first and middle of cultivation with heavy rainfall released amount is high, otherwise it was released very low at the end of cultivation and drought season. $N_2O$ emissions type was considered to relate with the rainfall pattern and soil water content. We obtained the result correlated with $N_2O$ emissions, in 2010, as the soil water and soil temperature were significant to $0.5718^{**}$ ($r$) and $0.4908^{**}$ ($r$) respectively, but soil EC was not significant to 0.2704 ($r$). In 2011, soil water was significant to $0.3394^*$ ($r$), but soil temperature and soil EC were not significant to 0.2138 ($r$) and 0.2462 ($r$) respectively. Also, $NO_3$-N and soil nitrogen ($NO_3-N+NH_4-N$) were not significant to 0.0575 ($r$) and 0.0787 ($r$) respectively. During the carrot cultivation period, the average emissions factor released by the nitrogen fertilizer application for 2 years was presumed to be 0.0025 $N_2O$-N kg / N kg. This factor was 4 times than the IPCC (0.0100 $N_2O$-N kg / N kg) factor.

• Journal of Mechanical Science and Technology
• /
• v.18 no.5
• /
• pp.808-813
• /
• 2004

The stress analysis on orthotropic composite cylindrical shells with one circular or one elliptical cutout subjected to an axial force is carried out by using an analytical and experimental method. The composite cylindrical shell governing equation of the Donnell's type is applied to this study and all results are presented by the stress concentration factor. The stress concentration factor is defined as the ratio of the stress on the region around a cutout to the nominal stress of the shell. The stress concentration factor is classified into the circumferential stress concentration factors and the radial stress concentration factors due to the cylindrical coordinate of which the origin is the center of a cutout. The considered loading condition is only axial tension loading condition. In this study, thus, the maximum stress is induced on perpendicular region against axial direction, on the coordinate. Various cutout sizes are expressed using the radius ratio, (equation omitted), which is the radius of a cutout over one of the cylindrical shell. Experimental results are obtained using strain gages, which are attached around a cutout of the cylindrical shell. As the result from this study, the stress concentration around a cutout can be predicted by using the analytical method for an orthotropic composite cylindrical shell having a circular or an elliptical cutout.

• Steel and Composite Structures
• /
• v.17 no.1
• /
• pp.21-46
• /
• 2014

This paper presents a simple n-order four variable refined theory for the bending and vibration analyses of functionally graded plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The present theory is variationally consistent, uses the n-order polynomial term to represent the displacement field, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The governing equations are derived by employing the Hamilton's principle and the physical neutral surface concept. The accuracy of the present solutions is verified by comparing the obtained results with available published ones.

• Korean Journal of Computational Design and Engineering
• /
• v.21 no.1
• /
• pp.90-98
• /
• 2016

When ships and offshore plants are flooded or the floating crane is equipped with a heavy object, these floating structures are excessively inclined. In this case, immersion, heel, and trim affecting the hydrostatic restoration performance are very large and are coupled each other. In this paper, in order to calculate a static equilibrium position of floating structures with excessive inclination, the nonlinear governing equations were constructed by sequential linearization. In the governing equation, the immersion, heel, and trim are fully coupled, and the equations are represented using a plane area, a primary moment, and a moment of inertia of the water plane area. Therefore, it is possible to calculate the additional factor related the water plane area for estimating stability. Position and orientation of the floating structure are obtained by iterative calculation. The calculated results are compared with the previous studies in the aspect to the performance and the accuracy.

• Structural Engineering and Mechanics
• /
• v.62 no.1
• /
• pp.65-77
• /
• 2017

The free vibration analysis of fluid conveying Timoshenko pipeline with different boundary conditions using Differential Transform Method (DTM) and Adomian Decomposition Method (ADM) has not been investigated by any of the studies in open literature so far. Natural frequencies, modes and critical fluid velocity of the pipelines on different supports are analyzed based on Timoshenko model by using DTM and ADM in this study. At first, the governing differential equations of motion of fluid conveying Timoshenko pipeline in free vibration are derived. Parameter for the nondimensionalized multiplication factor for the fluid velocity is incorporated into the equations of motion in order to investigate its effects on the natural frequencies. For solution, the terms are found directly from the analytical solution of the differential equation that describes the deformations of the cross-section according to Timoshenko beam theory. After the analytical solution, the efficient and easy mathematical techniques called DTM and ADM are used to solve the governing differential equations of the motion, respectively. The calculated natural frequencies of fluid conveying Timoshenko pipelines with various combinations of boundary conditions using DTM and ADM are tabulated in several tables and figures and are compared with the results of Analytical Method (ANM) where a very good agreement is observed. Finally, the critical fluid velocities are calculated for different boundary conditions and the first five mode shapes are presented in graphs.

• Advances in nano research
• /
• v.6 no.3
• /
• pp.279-298
• /
• 2018

Present investigation deals with the free vibration characteristics of nanoscale-beams resting on elastic Pasternak's foundation based on nonlocal strain-gradient theory and a higher order hyperbolic beam model which captures shear deformation effect without using any shear correction factor. The nanobeam is lying on two-parameters elastic foundation consist of lower spring layers as well as a shear layer. Nonlocal strain gradient theory takes into account two scale parameters for modeling the small size effects of nanostructures more accurately. Hamilton's principal is utilized to derive the governing equations of embedded strain gradient nanobeam and, after that, analytical solutions are provided for simply supported conditions to solve the governing equations. The obtained results are compared with those predicted by the previous articles available in literature. Finally, the impacts of nonlocal parameter, length scale parameter, slenderness ratio, elastic medium, on vibration frequencies of nanosize beams are all evaluated.

• Proceedings of the Korean Society of Tobacco Science Conference
• /
• 1999.10a
• /
• pp.9-12
• /
• 1999

Up to the 60's cigarette paper commercial grades were simply described as ' non combustible ', ' combustible ' or ' extra-combustible '. It was assumed that combustibility of the paper itself was correlated with cigarette combustibility. Since then, the characteristics of cigarette paper, like natural porosity and burning additives, which influence truly cigarette combustibility, have been described by various authors and it became clear to cigarette designers that paper combustibility was not generally a significant factor governing cigarette combustibility. On the other hand, for Roll Your Own(RYO)wrapping papers, the ECPCI has proposed to the CORESTA RYO Task Force to use paper combustibility, and specially the LCT test, to classify papers between low and high smoke delivery, and a new Task Force on PAPER COMBUSTIBILITY was recently set up to develop a recommended method. The objective of this presentation Is to show results demonstrating that for paper used on cigarettes, there is NO GENERAL CORTRELATION between PAPER and CIGARETTE combustibility. We will also show results confirming that, for the specific group of RYO booklet papers containing no burning additives, there is a correlation between paper combustibility and FCSA's Combustibility/smoke delivery. This apparent discrepancy will be explained by reviewing the role played by the various characteristics of cigarette paper in governing cigarette combustibility.

• Journal of the Korean Society of Costume
• /
• v.50 no.4
• /
• pp.89-102
• /
• 2000

The purpose of this study was to research Korean Jowoo-Guan and Chinese Hal-Guan and study transition and symbolism of the birds feather in the cap. The culture of ancient Korea was influenced by North Asia prior to the influence of the Chinese culture, One of the remarkable thing, as the cultural factor of North Asia is the birds worship thought. Korean Jowoo-Guan was derived from the birds worship thought. So in dealing with the plume of Korean Jowoo-Guan, we must recognize Worship to the bird and the symbolical meaning of the bird. The results of study was as follow. 1. Korean Jowoo-Guan was influenced worship to the sun, so it's wearing symbolized the governing class. As the Social development and governing class, the feathering cap was developed to a gold crown, and also the gold crown of Samguk times had been influenced style of North Asia culture. But afterwards the symbolical meaning of the bird was waning, only decorative meaning was remained. 2. Chinese Hal-Guan was warn in Joo-dynasty, but the symbolism of the plume in the cap was not similar to Korean Jowoo-Guan. Chinese Hal-Guan was symbolized bravery of superfluous soldier than Worship to the bird. But afterwards the symbolical meaning of bravery of superfluous soldier was waning, only decorative moaning was remained. 3. Though neighbor countries have mutually influenced and have similar cultural style, they have symbolism of themselves

• Structural Engineering and Mechanics
• /
• v.42 no.6
• /
• pp.761-781
• /
• 2012

The collapse of structures due to snow loads on roofs occurs frequently for steel structures and rarely for reinforced concrete structures. Since the most significant difference between these structures is related to their ability to handle dead loads, dead loads are believed to play an important part in the collapse of structures by snow loads. As such, the effect of dead loads on displacements and stress couples produced by live loads is presented for plates with different edge conditions. The governing equation of plates that takes into account the effect of dead loads is formulated by means of Hamilton's principle. The existence and effect of dead loads are proven by numerical calculations based on the Galerkin method. In addition, a closed-form solution for simply supported plates is proposed by solving, in approximate terms, the governing equation that includes the effect of dead loads, and this solution is then examined. The effect of dead loads on static live loads can be explained explicitly by means of this closed-form solution. A method that reflects the effects of dead loads on live loads is presented as an example. The present study investigates an additional factor in lightweight roof structural elements, which should be considered due to their recent development.

• Steel and Composite Structures
• /
• v.28 no.1
• /
• pp.99-110
• /
• 2018

In this paper, a new size-dependent quasi-3D plate theory is presented for wave dispersion analysis of functionally graded nanoplates while resting on an elastic foundation and under the hygrothermaal environment. This quasi-3D plate theory considers both thickness stretching influences and shear deformation with the variations of displacements in the thickness direction as a parabolic function. Moreover, the stress-free boundary conditions on both sides of the plate are satisfied without using a shear correction factor. This theory includes five independent unknowns with results in only five governing equations. Size effects are obtained via a higher-order nonlocal strain gradient theory of elasticity. A variational approach is adopted to owning the governing equations employing Hamilton's principle. Solving analytically via Fourier series, these equations gives wave frequencies and phase velocities as a function of wave numbers. The validity of the present results is examined by comparing them with those of the known data in the literature. Parametric studies are conducted for material composition, size dependency, two parametric elastic foundation, temperature and moisture differences, and wave number. Some conclusions are drawn from the parametric studies with respect to the wave characteristics.