• Clinical and Experimental Reproductive Medicine
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• 제41권3호
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• pp.97-107
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• 2014

The placenta is a temporary fetomaternal organ capable of supporting fetal growth and development during pregnancy. In particular, abnormal development and dysfunction of the placenta due to cha nges in the proliferation, differentiation, cell death, and invasion of trophoblasts induce several gynecological diseases as well as abnormal fetal development. Autophagy is a catalytic process that maintains cellular structures by recycling building blocks derived from damaged microorganelles or proteins resulting from digestion in lysosomes. Additionally, autophagy is necessary to maintain homeostasis during cellular growth, development, and differentiation, and to protect cells from nutritional deficiencies or factors related to metabolism inhibition. Induced autophagy by various environmental factors has a dual role: it facilitates cellular survival in normal conditions, but the cascade of cellular death is accelerated by over-activated autophagy. Therefore, cellular death by autophagy has been known as programmed cell death type II. Autophagy causes or inhibits cellular death via the other mechanism, apoptosis, which is programmed cell death type I. Recently, it has been reported that autophagy increases in placenta-related obstetrical diseases such as preeclampsia and intrauterine growth retardation, although the mechanisms are still unclear. In particular, abnormal autophagic mechanisms prevent trophoblast invasion and inhibit trophoblast functions. Therefore, the objectives of this review are to examine the characteristics and functions of autophagy and to investigate the role of autophagy in the placenta and the trophoblast as a regulator of cell death.

• Geomechanics and Engineering
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• 제15권4호
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• pp.965-972
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• 2018

In deep braced excavations, struts and walers play an essential role in the whole supporting system. For multi-level strut systems, accidental strut failure is possible. Once a single strut fails, it is possible for the loads carried from the previous failed strut to be transferred to the adjacent struts and therefore cause one or more struts to fail. Consequently, progressive collapse may occur and cause the whole excavation system to fail. One of the reasons for the Nicoll Highway Collapse was attributed to the failure of the struts and walers. Consequently, for the design of braced excavation systems in Singapore, one of the requirements by the building authorities is to perform one-strut failure analyses, in order to ensure that there is no progressive collapse when one strut was damaged due to a construction accident. Therefore, plane strain 2D and three-dimensional (3D) finite element analyses of one-strut failure of the braced excavation system were carried out in this study to investigate the effects of one-strut failure on the adjacent struts.

• 한국주거학회논문집
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• 제26권5호
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• pp.1-8
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• 2015

In South Korea, a certain number of temporary housings are pre-produced and stored in a warehouse, which are later relocated and installed in the areas damaged by disasters. Through the supply of temporary housings upon the occurrence of a disaster, disaster victims are able to rapidly go back to their everyday lives, and the social confusion formed after the occurrence of a disaster is reduced. Although temporary housings can be used for various purposes, they are currently being used only for helping disaster victims and are thus facing the difficulty of continuing technology development due to their low marketability. To increase the use of temporary housings, this study was conducted to formulate a plan for the recycled use of temporary housings in non-disaster situations. This study intended to open wide the possibility of operating temporary housings regardless of the type, period, and scale of the disaster, and to propose a plan for the reuse of temporary housings in non-disaster situations.

• Earthquakes and Structures
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• 제4권3호
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• pp.299-324
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• 2013

The current research focuses on the seismic vulnerability assessment of typical Southern Europe buildings, based on processing of a large set of observational damage data. The presented study constitutes a sequel of a previous research. The damage statistics have been enriched and a wider damage database (178578 buildings) is created compared to the one of the first presented paper (73468 buildings) with Damage Probability Matrices (DPMs) after the elaboration of the results from post-earthquake surveys carried out in the area struck by the 7-9-1999 near field Athens earthquake. The dataset comprises buildings which developed damage in several degree, type and extent. Two different parameters are estimated for the description of the seismic demand. After the classification of damaged buildings into structural types they are further categorized according to the level of damage and macroseismic intensity. The relative and the cumulative frequencies of the different damage states, for each structural type and each intensity level, are computed and presented, in terms of damage ratio. Damage Probability Matrices (DPMs) are obtained for typical structural types and they are compared to existing matrices derived from regions with similar building stock and soil conditions. A procedure is presented for the classification of those buildings which initially could not be discriminated into structural types due to restricted information and hence they had been disregarded. New proportional DPMs are developed and a correlation analysis is fulfilled with the existing vulnerability relations.

• Steel and Composite Structures
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• 제26권5호
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• pp.549-556
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• 2018

Progressive building collapse occurs when failure of a structural component leads to the failure and collapse of surrounding members, possibly promoting additional failure. Global system collapse will occur if the damaged system is unable to reach a new static equilibrium configuration. The most common type of primary failure which led to the progressive collapse phenomenon, is the sudden removal of a column by various factors. In this study, a method is proposed to prevent progressive collapse phenomena in structures subjected to removal of a single column. A vierendeel peripheral frame at roof level is used to redistribute the removed column's load on other columns of the structure. For analysis, quasi-static approach is used which considers various load combinations. This method, while economically affordable is easily applicable (also for new structures as well as for existing structures and without causing damage to their architectural requirements). Special emphasis is focused on the evolution of vertical displacements of column removal point. Even though additional stresses and displacements are experienced by removal of a structural load bearing column, the proposed method considerably reduces the displacement at the mentioned point and prevents the collapse of the structural frame.

• Steel and Composite Structures
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• 제25권5호
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• pp.617-624
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• 2017

In this study, a new empirical method is presented to obtain Dynamic Increase Factor (DIF) in nonlinear static analysis of structures against sudden removal of a gravity load-bearing element. In this method, DIF is defined as a function of minimum ratio of difference between maximum moment capacity ($M_u$) and moment demand ($M_d$) to plastic moment capacity ($M_p$) under unamplified gravity loads of elements. This function determines the residual strength of a damaged building before amplified gravity loads. For each column removal location, a nonlinear dynamic analysis and a step-by-step nonlinear static analysis are carried out and the modified empirical DIF formulas are derived, which correspond to the ratio min $[(M_u-M_d)/M_p]$ of beams in the bays immediately adjacent to the removed column, and at all floors above it. Therefore, the new DIF can be used with nonlinear static analysis instead of nonlinear dynamic analysis to assess the progressive collapse potential of a moment frame structure. The proposed DIF formulas can estimate the real residual strength of a structure based on critical member.

• 대한의생명과학회지
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• 제11권3호
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• pp.267-274
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• 2005

Formaldehyde (FA) is an important industrial chemical, but it can cause allergic reactions, sick building syndrome and so on. It has also been observed to cause cancer in scientific studies using laboratory animals, and it even causes cancer in humans. Natural products such as ginseng and pine needle containing complicated mixtures of organic chemicals are widely used in the world, because their effective components are responsible for some pharmacological activities including antioxidative effect, anticancer effect. We investigate the effect of Korean ginseng (GE), pine needle extract (PE) and combined GE and PE (cNPE) on mouse lung injury by FA exposure. GE, PE and cNPE was directly transported to pulmonary cells through respiratory organ by nebulizer inhalation. In the case of FA exposure, the pulmonary structure was damaged and its function became abnormal. However, cNPE-FA, GE-FA, and PE-FA treated groups showed similar with the control group compared with FA group. Among them, GE was proved to be more effective than any other extracts. These results demonstrate that natural product extracts could protect pulmonary structure and function against FA exposure.

• 셀메드
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• 제6권1호
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• pp.1.1-1.9
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• 2016

Osteoarthritis (OA) is the leading medical condition for which patients use alternative treatments including the natural remedies. The aim of this review is to describe the dietary supplements and herbal remedies most commonly used in patients with osteoarthritis with an emphasis on the efficacy and safety of these natural remedies. Glucosamine and chondroitin sulfate, two of the molecular building blocks found in articular cartilage, are the most commonly used remedies in OA treatment. Most clinical researches suggest that glucosamine and chondroitin show efficacy in reducing or improving symptoms and their ability to arrest progression of the disease or regenerate damaged cartilage. Patented formulations of both remedies are recommended by several therapeutic guidelines for use as first line background OA treatment. Reliable evidence that the combination is more effective than either agent alone is however still lacking. Several other herbs or remedies are promoted for treating osteoarthritis such as S-adenosylmethionine, methylsulfonylmethane, Harpagophytum procumbens (devil's claw), Curcuma longa (turmeric), Zingiber officinale (ginger), and capsaicin but there is no reliable evidence on long-term efficacy or safety. The clinical usefulness of these remedies is therefore rather limited currently.

• Structural Engineering and Mechanics
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• 제35권6호
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• pp.735-758
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• 2010

The paper proposes two methodologies for damage identification from measured natural frequencies of a contiguously damaged reinforced concrete beam, idealised with distributed damage model. The first method identifies damage from Iso-Eigen-Value-Change contours, plotted between pairs of different frequencies. The performance of the method is checked for a wide variation of damage positions and extents. The method is also extended to a discrete structure in the form of a five-storied shear building and the simplicity of the method is demonstrated. The second method is through smeared damage model, where the damage is assumed constant for different segments of the beam and the lengths and centres of these segments are the known inputs. First-order perturbation method is used to derive the relevant expressions. Both these methods are based on distributed damage models and have been checked with experimental program on simply supported reinforced concrete beams, subjected to different stages of symmetric and un-symmetric damages. The results of the experiments are encouraging and show that both the methods can be adopted together in a damage identification scenario.

• Structural Engineering and Mechanics
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• 제45권6호
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• pp.803-819
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• 2013

This paper addresses two main issues relevant to the structural assessment of buildings subjected to explosions. The first issue regards the robustness evaluation of steel frame structures: a procedure is provided for computing "robustness curves" and it is applied to a 20-storey steel frame building, describing the residual strength of the (blast) damaged structure under different local damage levels. The second issue regards the precise evaluation of blast pressures acting on structural elements using Computational Fluid Dynamic (CFD) techniques. This last aspect is treated with particular reference to gas explosions, focusing on some critical parameters (room congestion, failure of non-structural walls and ignition point location) which influence the development of the explosion. From the analyses, it can be deduced that, at least for the examined cases, the obtained robustness curves provide a suitable tool that can be used for risk management and assessment purposes. Moreover, the variation of relevant CFD analysis outcomes (e.g., pressure) due to the variation of the analysis parameters is found to be significant.