• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.4
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• pp.43-49
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• 2003

This research work has been carried out for finding J-integral in mode II of CFRP(carbon fiber reinforced plastics) laminate plates based on the classical bar theory in dynamic conditions with consideration of the effect of inertia forces, eventually to lead to finding the dynamic inter-layer fracture toughness. Dynamic inter-layer fracture toughness was found by a self-made ENF(End Notched Flexure) experimental apparatus using Split Hopkinson's Bar(SHPB), and also observed the variation of the fracture toughness haying different resin contents and fiber arrangements of CFRP specimen([$0_3^{\circ}/90_3^{\circ}/0_6^{\circ}/90_3^{\circ}/0_3^{\circ}$], [$0_{20}^{\circ}$], [$0_5^{\circ}/90_{10}^{\circ}/0_5^{\circ}$]). As an experimental result, in either cases of quasi-static or dynamic load condition, the critical load and the inter-layer fracture toughness increased sharply depending on the increase of resin contents. Therefore, it could, be concluded that the effect by resin contents is the major factor determining the inter-layer fracture toughness in the CFRP laminate plates.

• Structural Engineering and Mechanics
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• v.16 no.2
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• pp.195-217
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• 2003

This paper, which is an extension of a previous work by Viola et al. (2002), deals with the dynamic stability of beams under a triangularly distributed sub-tangential forces when the effect of an elastically restrained end is taken into account. The sub-tangential forces can be realised by a combination of axial and tangential follower forces, that are conservative and non-conservative forces, respectively. The studied beams become unstable in the form of either flutter or divergence, depending on the degree of non-conservativeness of the distributed sub-tangential forces and the stiffness of the elastically restrained end. A non-conservative parameter ${\alpha}$ is introduced to provide all possible combinations of these forces. Problems of this kind are usually, at least in the first approximation, reduced to the analysis of beams according to the Bernoulli-Euler theory if shear deformability and rotational inertia are negligible. The equation governing the system may be derived from the extended form of Hamilton's principle. The stability maps will be obtained from the eigenvalue analysis in order to define the divergence and flutter domain. The passage from divergence to flutter is associated with a noticeable lowering of the critical load. A number of particular cases can be immediately recovered.

• Steel and Composite Structures
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• v.4 no.4
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• pp.281-301
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• 2004

The paper begins by presenting a unified variational approach to the lateral-torsional buckling (LTB) analysis of doubly symmetric prismatic and tapered thin-walled beams with open cross-sections, which accounts for the influence of the pre-buckling deflections. This approach (i) extends the kinematical assumptions usually adopted for prismatic beams, (ii) consistently uses shell membrane theory in general coordinates and (iii) adopts Trefftz's criterion to perform the bifurcation analysis. The proposed formulation is then applied to investigate the influence of the pre-buckling deflections on the LTB behaviour of prismatic and web-tapered I-section simply supported beams and cantilevers. After establishing an interesting analytical result, valid for prismatic members with shear centre loading, several elastic critical moments/loads are presented, discussed and, when possible, also compared with values reported in the literature. These numerical results, which are obtained by means of the Rayleigh-Ritz method, (i) highlight the qualitative differences existing between the LTB behaviours of simply supported beams and cantilevers and (ii) illustrate how the influence of the pre-buckling deflections on LTB is affected by a number of factors, namely ($ii_1$) the minor-to-major inertia ratio, ($ii_2$) the beam length, ($ii_3$) the location of the load point of application and ($ii_4$) the bending moment diagram shape.

• Steel and Composite Structures
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• v.8 no.2
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• pp.159-178
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• 2008

An analytical procedure is presented for the determination of the buckling load and the buckling temperature of a straight, slender, geometrically perfect, axially loaded, translationally and rotationally restrained steel column exposed to fire. The exact kinematical equations of the column are considered, but the shear strain is neglected. The linearized stability theory is employed in the buckling analysis. Behaviour of steel at the elevated temperature is assumed in accordance with the European standard EC 3. Theoretical findings are applied in the parametric analysis of restrained columns. It is found that the buckling length factor decreases with temperature and depends both on the material model and stiffnesses of rotational and translational restraints. This is in disagreement with the buckling length for intermediate storeys of braced frames proposed by EC 3, where it is assumed to be temperature independent. The present analysis indicates that this is a reasonable approximation only for rather stiff rotational springs.

• Korean Journal of Adult Nursing
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• v.18 no.3
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• pp.488-499
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• 2006

Purpose: Behavioral symptoms in dementia (BSD) are one of the most disturbing behaviors to caregivers and a major reason for nursing home placement. Behavioral symptoms are often treated with psychotropic drugs (PD), however, the effect of such drugs for the frail elderly dementia patient is not certain because of their critical adverse effects. Theoretical model applicable to nursing practice for BSD in nursing homes, which is essential in guiding and evaluating such interventions, is absent. This article presents the process of developing a theoretical model of BSD in nursing homes. Method: Using Walker and Avants' theory synthesis method, three behavior models and two system models were incorporated into the proposed model to provide the theoretical and analytical explanation of the relationships between PD usage, its determinants, and BSD. Results: Resident variables and nursing home variables related to the two focal concepts (i.e., PD usage and BSD) were identified. Resident variables include demographical characteristics such as age and gender, and dementia-compromised functions such as cognitive and functional impairment. Nursing home variables include facility characteristics such as ownership type and size, and physical and psychosocial environment. Conclusion: The proposed model suggests that fulfillment of resident unmet needs through improvement of physical and psychosocial environment may produce better health outcomes of nursing home residents with BSD. Assessment and intervening environmental triggers of such behaviors are also suggested to be prior to the PD usage.

• Journal of architectural history
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• v.25 no.2
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• pp.21-30
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• 2016

Autonomia movement that emerged in Italy in the 1960s from workerist (operaismo) communism gives historical and discursive context to Manfredo Tafuri's famous criticism of ideology. His thesis on the death of architecture was a radical criticism of Keynesian intervention which was a strategy to cope with the Great Depression. For him, this capitalist development had taken away ideological prefiguration from architecture. At least Tafuri's this early intellectual phase was formed in the wake of magazine Contrapiano and Antonio Negri's influence. Tafuri almost entirely adapted Negri's thought on the importance of capitalist innovation that was uncovered by Keynes, Schumpeter, and Manheim and the periodization in modern history. When we read Tafuri's text with this concrete context, we can avoid being plunged into his abstruseness. On the other hand, 1980's Korea cannot understand Tafuri comprehensibly. 1980's situation to struggle to acquire democracy prescribed only one mode of reception of Tafuri's historiography in Korea. Tafuri's so-called pessimist view point could not satisfy student activists. They want to take intellectual means to sustain student movement and to secure political dynamics of protest. But at the same time they have anxiety to understand tafuri's thesis that they consider ad a critical theory for Korean Architecture. Double contexts of Tafuri's criticism of ideology bring to light to historicize both Tafuri's historiography itself and reception of his text in Korea.

• Progress in Superconductivity
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• v.5 no.2
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• pp.89-93
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• 2004

We have studied alternating transport current losses in the vertically stacked high temperature superconducting tapes(HTS) using numerical techniques. In the case of stacked conductors, HTS tapes are exposed to self-field generated by transport current itself and also experienced external magnetic field around adjacent tapes. It is well known that magnetic interactions between neighbored tapes have significant effect on their properties of superconducting tapes such as current distribution, AC loss, and critical current. In this paper, we investigated the transport current losses in stacked conductors consisting of a few of the HTS tapes using numerical analysis. Current distributions are calculated in HTS tape cross-section taking account of magnetic field dependencies, which are represented superconducting nonlinear properties. Dissipated losses in tape and stacked conductors were integrated with current distribution and electric field intensity in the whole conductor region. Finally estimated results were discussed and verified through the analytical theory.

• Journal of architectural history
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• v.8 no.3 s.20
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• pp.75-89
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• 1999

Under the WTO system, global standardization of professionalism in architecture practice calls for transformation of curriculum in architectural education in Korea. This paper compares the curriculum standards of international accrediting authorities such as NAAB and RIBA based on UIA accord which defines fundamental knowledge and abilities of an architect. As a result this paper extracts 51 achievement oriented criteria of architectural education in Korea. It can be categorized as communication, design, cultural context(history and theory, human behavior and social aspects), technical systems(structural systems, environmental control systems, construction material and assemblies) and practice(project process, project economics and business management, laws and regulations). Based on this recommended Korean curriculum standards, current curriculum is analyzed focusing on the 5 architectural programs in Seoul. Through this analysis, it became clear that some area - social and economic aspects in architecture, sustainability in architecture, understanding and selection of construction material, assemblies and environmental control system, recycling of existing building, professional liability, professional rules of conduct, project economics and project management - need to be covered and emphasized to meet the international standards in professional education in architecture. The result in this paper will be used as a basic data in the process of finding the direction of restructuring curriculum for professional architectural education in Korea.

• Geotechnical Engineering
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• v.10 no.1
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• pp.7-18
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• 1994

A new model for describing the behavior of clay under monotonic and cyclic loading is proposed. This model uses the hyperbolic representation for the stress -strain relationship in overconsolidated state and it describes undrained effective stress path on the basis of the critical state theory. The developed constitutive model by using an energy dissipation equation can describe the behavior of clay in heavily overconsolidated state as u.ell as lightly overconsolidated state under monotonic loading. In order to extend the model for the behavior of clay under cyclic loading, a shift function of undrained stress spacing ratio is introduced in the constitutive model developed for monotonlc loading. A single additional parameter is required to represent the cyclic effect and it can be reasonably deter mined from the test results. The measured behavior in undrained cyclic triaxial tests has been easily and precisely predicted by the newly developed constitutive model.

• Journal of applied mathematics & informatics
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• v.29 no.3_4
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• pp.529-546
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• 2011

A deterministic tuberculosis model for theoretically assessing the potential impact of the combined effects of case detection in the presence of treatment is formulated. The qualitative features of its equilibria are analyzed and it is found that the disease-free equilibrium may not be globally asymptotically stable when the reproduction number is less than unity. This disease threshold number is further used to assess the impact of active TB case finding alone and in conjunction with treatment. A critical threshold parameter ${\Theta}$ say for which case detection will have a positive impact is derived. Using the Centre Manifold theory, the model may exhibit the phenomenon of backward bifurcation (coexistence of a locally stable endemic equilibrium with a stable disease-free equilibrium) when the reproduction number is less than unity. It is shown that the possibility of backward bifurcation occurring decreases with increase case detection. Graphical representations suggest that increase in case finding accompanied by treatment of detected TB cases, result in a marked decrease of TB cases (both latent and active TB).