• 신재생에너지
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• 제2권4호
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• pp.4-11
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• 2006

The idea of $CO_2$ sequestration in the ocean is proposed to be an effective mitigation strategy to counteract potential global warming due to the greenhouse effect. Therefore, in the present study, calculations of the dissolution behavior of $CO_2$ hydrate when liquid carbon dioxide is released at 1,000m and 1,500m in depth are performed. The results show the liquid $CO_2$ injected in the ocean becomes $CO_2$ bubble at between 350 m in depth, and the injection from a moving ship is a more effective method of dissolution than through a fixed pipeline. It so also noted that the ultimate plume generated from $CO_2$ bubbles repeats expansion and shrinking due to the peeling from a fixed pipeline.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.289-296
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• 2000

Dynamic responses of a bridge retrofitted with cable restrainers are examined under seismic excitations. A simplified and idealized mechanical model is developed to analyze the effects of the restrainers, which can consider the plastic behavior as well as the fracture of the cable. Using the proposed model, the effects of the stiffness and the clearance length of the restrainer upon the global bridge seismic behaviors are estimated. The changes of pounding forces, shear forces, and bending moments due to the application of restrainers are also investigated. The main effect of restrainers upon global bridge motions is found to reduce the relative distances between adjacent vibrations units. It is also found that the relative distances are decreased as the clearance length of the restrainer decreases and the stiffness of restrainer increases.

• Structural Engineering and Mechanics
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• 제24권3호
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• pp.355-374
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• 2006

Thin walled steel bridge-piers/columns are vulnerable to damage, when subjected to earthquake excitations. Local buckling, global buckling or interaction between local and global buckling usually is the cause of this damage, which results in significant strength reduction of the member. In this study new innovative design concepts, "thin-walled corrugated steel columns" and "thin-walled cellular steel columns" are presented, which allow the column to undergo large plastic deformations without significant strength reduction; hence dissipate energy under cyclic loading. It is shown that, compared with the conventional designs, circular and stiffened box sections, these new innovative concepts might results in cost-effective designs, with improved buckling and ductility properties. Using a finite element model, that takes the non-linear material properties into consideration, it is shown that the corrugations will act like longitudinal stiffeners that are supporting each other, thus improving the buckling behavior and allowing for reduction of the overall wall thickness of the column.

• 한국멀티미디어학회논문지
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• 제21권12호
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• pp.1473-1480
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• 2018

The extraction and recognition of human motion characteristics need to combine biometrics to determine and judge human behavior in the movement and distinguish individual identities. The so-called biometric technology, the specific operation is the use of the body's inherent biological characteristics of individual identity authentication, the most noteworthy feature is the invariance and uniqueness. In the past, the behavior recognition technology based on the single characteristic was too restrictive, in this paper, we proposed a mixed feature which combined global silhouette feature and local optical flow feature, and this combined representation was used for human action recognition. And we will use the KTH database to train and test the recognition system. Experiments have been very desirable results.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제30권2호
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• pp.203-220
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• 2023

A new modification of the SIS epidemic model incorporating the adaptive host behavior is proposed. Unlike the common situation in most epidemic models, this system has two disease-free equilibrium points, and we were able to prove that as the basic reproduction number approaches the threshold of 1, these two points merge and a Bogdanov-Takens bifurcation of codimension three occurs. The occurrence of this bifurcation is a sign of the complexity of the dynamics of the system near the value 1 of basic reproduction number. Both local and global stability of disease-free and endemic equilibrium point are studied.

• Structural Engineering and Mechanics
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• 제18권5호
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• pp.645-669
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• 2004

In seismic analysis of moment-resisting frames, beam-column connections are often modeled with rigid joint zones. However, it has been demonstrated that, in ductile reinforced concrete (RC) moment-resisting frames designed based on current codes (to say nothing of older non-ductile frames), the joint zones are in fact not rigid, but rather undergo significant shear deformations that contribute greatly to global drift. Therefore, the "rigid joint" assumption may result in misinterpretation of the global performance characteristics of frames and could consequently lead to miscalculation of strength and ductility demands on constituent frame members. The primary objective of this paper is to propose a rational method for estimating the hysteretic joint shear behavior of RC connections and for incorporating this behavior into frame analysis. The authors tested four RC edge beam-column-slab connection subassemblies subjected to earthquake-type lateral loading; hysteretic joint shear behavior is investigated based on these tests and other laboratory tests reported in the literature. An analytical scheme employing the modified compression field theory (MCFT) is developed to approximate joint shear stress vs. joint shear strain response. A connection model capable of explicitly considering hysteretic joint shear behavior is then formulated for nonlinear structural analysis. In the model, a joint is represented by rigid elements located along the joint edges and nonlinear rotational springs embedded in one of the four hinges linking adjacent rigid elements. The connection model is able to well represent the experimental hysteretic joint shear behavior and overall load-displacement response of connection subassemblies.

• 디지털융복합연구
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• 제13권7호
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• pp.69-78
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• 2015

노사관계는 향후 융복합 글로벌환경에서 기업들이 지속적인 경쟁력을 확보하기 위해 반드시 풀고 가야할 핵심과제로 부각되고 있다. 본 연구는 융복합형 노사갈등이 이직의도에 미치는 영향에 있어서 노조참여행동의 매개효과 검증해 보고자 하는데 연구의 목적을 두었다. 자료의 수집은 대전시, 충청남 북도에 위치한 중소기업의 종업원 491명을 대상으로 조사하였다. 분석 결과는 다음과 같다. 첫째, 노사갈등이 노조참여행동에 정(+)에 영향을 미치는 것으로 나타났다. 둘째, 노조참여행동은 이직의도에 부(-)의 영향을 미치는 것으로 나타났다. 셋째, 노조참여행동은 노사갈등과 이직의도와의 관계에서 매개역할을 하는 것으로 나타났다. 따라서 노조지도부가 노조원들의 이익과 욕구에 민감히 반응하고 이를 통하여 노조의 필요성과 가치를 지속적으로 제고시키기 위한 노력이 필요하다.

• Journal of Electrochemical Science and Technology
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• 제2권3호
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• pp.174-179
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• 2011

The mesoscopic $Sb_2S_3$-sensitized photoelectrochemical solar cells using cobalt redox electrolyte exhibit nonlinear behavior of power conversion efficiency with illuminated sun intensity. From the measurement of bulk diffusion and electrochemical impedance spectroscopy studies, we suggest that the nonlinearity of device performance with illuminated sun intensity is attributed not to the slow bulk diffusion problem of cobalt electrolyte but to the limited mass transport in narrowed pore volume in mesoscopic $TiO_2$ electrode.

• 한국안전학회지
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• 제9권1호
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• pp.140-145
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• 1994

Contributions of global warming potentials on CFC(Chlorofluorocarbon) and Ozone were calculated by Stefan-Boltzmann's law and environmental effects of its were discussed. As the greenhouse effect on the unit volume of CFC is the most strong in the infrared gases and the destruction of Ozone in stratosphere is also depends on CFC, therefore release of CFC should be prohibited. But the effect of restriction on CFC will be appeared more than 10 years later. Eventhough the Ozone layer is related to global warming, It should be protected because of maitaining food chain mode of life, preventing human disease, for example, cataract, dermatics etc.

• 대한수학회지
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• 제42권6호
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• pp.1137-1152
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• 2005

In this article we prove the existence of the solution to the mixed problem for Euler-Bernoulli beam equation with memory condition at the boundary and we study the asymptotic behavior of the corresponding solutions. We proved that the energy decay with the same rate of decay of the relaxation function, that is, the energy decays exponentially when the relaxation function decay exponentially and polynomially when the relaxation function decay polynomially.