• Journal of Advanced Research in Ocean Engineering
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• v.1 no.3
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• pp.157-167
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• 2015

In order to provide simple and accurate wave theory in design of offshore structure, an analytical approximation is introduced in this paper. The solution is limited to flat bottom having a constant water depth. Water is considered as inviscid, incompressible and irrotational. The solution satisfies the continuity equation, bottom boundary condition and non-linear kinematic free surface boundary condition exactly. Error for dynamic condition is quite small. The solution is suitable in description of breaking waves. The solution is presented with closed form and dispersion relation is also presented with closed form. In the last century, there have been two main approaches to the nonlinear problems. One of these is perturbation method. Stokes wave and Cnoidal wave are based on the method. The other is numerical method. Dean's stream function theory is based on the method. In this paper, power series method was considered. The power series method can be applied to certain nonlinear differential equations (initial value problems). The series coefficients are specified by a nonlinear recurrence inherited from the differential equation. Because the non-linear wave problem is a boundary value problem, the power series method cannot be applied to the problem in general. But finite number of coefficients is necessary to describe the wave profile, truncated power series is enough. Therefore the power series method can be applied to the problem. In this case, the series coefficients are specified by a set of equations instead of recurrence. By using the set of equations, the nonlinear wave problem has been solved in this paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.323-329
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• 2011

Most current design codes of concrete structures adopt the partial safety factor format to assure the proper safety margin or reliability against various limit states as a practical design tool. The safety factors, load and resistance factors and so on, are determined based on the theory of structural reliability, which takes into account the statistical uncertainties of both loads and resistances. The establishment of statistical models for load and resistance should be preceded the application of reliability theory. In this paper, especially the influence of the statistical variations of resistance models, which are described in terms of strength of concrete, strength of reinforcements and sectional dimensions and so on, are examined and the probabilistic models for resistance of reinforced concrete members were developed. The statistical data were collected on local tests and experiments in Korea and the Monte Carlo simulation (MCS) technique was used. The results of this paper may be useful and valuable in calibration of design code in this country.

• The Journal of the Korea Contents Association
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• v.13 no.5
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• pp.58-70
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• 2013

This study focuses on the fact that intrinsic motivation which becomes the force to promote narrative is reinforced as a polyphonic structure through the psychodynamics of fear and desire internalized in a character, and from this perspective, it analyzes character rising strategies shown in Pixar's movie, . To verify fear and desire of a character, this study uses Enneagram personality types theory as the frame of analysis and reaches the following conclusions: (1) The main character, Carl's emotion originated from fear and desire was metaphorized as Muntz and Russell each, so the inside psychodynamics and the outer event visualizing it are set as contrapuntal composition. (2) However, inversely to the enhancement of Carl's polyphonicity, that excellent strategy works as the limit that restricts the psychodynamics of Muntz and Russell to a certain range. Lastly, it is expected that this study will be suggested as a sort of methodology about character rising strategies as turned into the database to which the result of follow-up research will be added, too.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.899-902
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• 2008

The GFRP rebar have been interested as the substituting material of the conventional steel rebar to the concrete structure for high durable concrete structure. The GFRP rebar, however, has different way to be fabricated and mechanical characteristics comparing with the conventional steel rebar. Therefore, to apply the GFRP rebar to the construction field, it needs the proper and reasonable design theory, codes and guidelines. In this study, for the design recommendation of the GFRP rebar, ACI440.IR and ISIS Canada design manual were investigated and concluded that the design theory of ISIS Canada design manual was relatively better design concept considering the limit state of the GFRP rebar in design and analysis. With this design concept, new design equation for the GFRP rebar was suggested and investigated with other design equations.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.1-11
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• 2001

The purpose of this study is to develop the main program and pre/post processor for the geometric and plastic non-linear analysis of steel jacket structures subjected to wave and earthquake loadings. In this paper, steel jackets are modelled using geometric non-linear space frames and wave loadings re evaluated based on Morrison equation using the linear Airy theory and the fifth Stokes theory. Random wave is generated using JONSWAP spectrum. For earthquake analysis, dynamic analysis is performed using artificial earthquake time history. Also the plastic hinge method is presented for limit analysis of steel jacket. In the companion paper, the pre/post processor is developed and the numerical examples are presented for linear and non-linear dynamic analysis of steel jackets.

• Earthquakes and Structures
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• v.14 no.3
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• pp.249-259
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• 2018

This paper aims to assess the seismic risk of a plane moment-resisting frames (MRFs) consisting of concrete-filled double skin steel tube (CFDST) columns and I-section steel beams. Firstly, three typical limit performance levels of CFDST structures are determined in accordance with the cyclic tests of seven CFDST joint specimens with 1/2-scaled and the limits stipulated in FEMA 356. Then, finite element (FE) models of the test specimens are built by considering with material degradation, nonlinear behavior of beam-column connections and panel zones. The mechanical behavior of the concrete material are modeled in compression stressed condition in trip-direction based on unified strength theory, and such numerical model were verified by tests. Besides, numerical models on 3, 6 and 9-story CFDST frames are established. Furthermore, the seismic responses of these models to earthquake excitations are investigated using nonlinear time-history analyses (NTHA), and the limits capacities are determined from incremental dynamic analyses (IDA). In addition, fragility curves are developed for these models associated with 10%/50yr and 2%/50yr events as defined in SAC project for the region on Los Angeles in the Unite State. Lastly, the annual probabilities of each limits and the collapse probabilities in 50 years for these models are calculated and compared. Such results provide risk information for the CFDST-MRFs based on the probabilistic risk assessment method.

• Communications of Mathematical Education
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• v.34 no.3
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• pp.355-372
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• 2020

The concept of infinite series is an important subject of major mathematics curriculum in college. For several centuries it has provided learners not only counter-intuitive obstacles but also central role of analysis study. As the understanding in concept on infinite series became foundation of development of calculus in history of mathematics, it is essential to present students to study higher mathematics. Most students having concept of infinite sum have no difficulty in mathematical contents such as convergence test of infinite series. But they have difficulty in organizing concept of infinite series of partial sum. Thus, in this study we try to analyze construct the concept of infinite series in terms of APOS theory and genetic decomposition. By checking to construct concept of infinite series, we try to get an useful educational implication on teaching of infinite series.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.103-108
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• 2005

The purpose of numerical analysis is to design an effective algorithm to realize some mathematical model on computer. In general the approximate value, which is obtained from computer operation, is not the same as the real value that is given by mathematical theory. Therefore the mr estimate measuring how approximate value is near to the real value, is the most significant task to evaluate the efficiency of algorithm. The limit of an error is used for mr estimation at the most case, but the exact mr evaluation could not be expected to get for there is no way to know the real value of the given problem. Wegmann's method has been researched, which is one of the solution to derive the numerical conformal mapping. We proposed an improved method for convergency by applying a low frequency filter to the Wegmann's method. In this paper we investigate error analysis based on some mathematical theory and propose an effective method which makes us able to estimate an error if the real value is not acquired. This kind of proposed method is also proved by numerical experiment.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.145-151
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• 2009

Current highway design standards is based on the safety under the free flow condition. The length of deceleration lane is also determined in terms of the deceleration distance which is necessary for the driers to adjust the vehicle speed from the speed limit on the main road to that on the exit ramp of the interchange. However, the queues are frequently developed on the deceleration, and the following vehicles to exit must decelerate on the main road. It may cause delay on the main road and traffic accidents. This study is to suggest a methodology to minimize such problems with the shock-wave theory. The queue length of exiting vehicles can be estimated by the design speeds, traffic volumes of main road and the exiting ramp, and the countermeasures to the operational problems. According to the results, the queue length can be shortened to 80% by upgrading the design speed of exit ramp as the amount of 10km/h. Fifty percent of queue length can be shortened by adding an additional lane on the ramp to two lanes.

• Hwankyungkyoyuk
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• v.13 no.1
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• pp.96-110
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• 2000

There are some considerations that must take into account in environmental education in the aspect of the difference of value clarification between ecological and economic viewpoint on environment. Although we have a tendency to think that the differences are unavoidable because we are on the economy-oriented life, we should realize that such emphasis to economics comes from the differences between ecological and economic view point on environment. We have lived and thought on the basis of Economic view point, especially, environmental policies are established on the basis of economic efficiency. But this tendency has become great obstacles to environmental ethics education because it dilutes the reason of natural preservation and removes the fundamental reasons why the nature should be preserved. Therefore it is very difficult to balance the value clarification between economic and ecological viewpoint in actual life. Furthermore, environmental problems can not be solved only through economic approach, because of their limits to belief solving from providing incentives. It is very important to make people have a way of thinking which economic activities and debates can be made on the ecological resources. Therefore we can compare this relation to CHAE-YONG founded on Buddism and Chinese philosophy. CHAE means essence of every reaction in the cosmos, and YONG means the reaction itself. CHAE is regarded to ecological resources, and YONG is thought to every-day economic activities. YONG is not able to existwithout CHAE. If economic activities can be done on the basic limit of ecological resources, we can build suitable environment to living condition. We call this appropriate environment as SANG. In other words, the connection of CHAE-YONG-SANG means ecological resources - economic activities - sustainable environment. It is realized that the relations between economics and ecology should be equalized for the balanced environmental ethics education. This study tries to get out of unbalanced relations between economics and ecology from the persepectives of CHAE-YONG-SANG and it was done to suggest an alternative environmental ethics education program