• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.213-216
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• 2005

Salt attack and freezing & thawing test, one of the combined deterioration tests was performed to explore the mechanism of concrete structure deterioration under marine environment. Simple submerging test was proceeded to draw out its diffusion factor with salt water at the same time. Some of the mechanisms were driven with using three types of cements and four kinds of salt water concentrations. $\circ$ TBC was more durable than OPC or SRC for freezing and thawing action $\circ$ The higher chloride concentration of salt water was, the faster relative dynamic elastic modulus decreased and the higher the loss of weight was. $\circ$ The diffusion factor of TBC was smaller than those of TBC or SRC at simple submergence of concrete specimens into salt water.

• Korean Circulation Journal
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• v.52 no.4
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• pp.251-264
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• 2022

Heart failure with preserved ejection fraction (HFpEF) accounts for approximately half of all heart failure (HF) cases. The prevalence of HFpEF is increasing due to an aging population with hypertension, diabetes mellitus, and obesity. HFpEF remains a challenging clinical entity due to a lack of effective treatment options. Traditional HF medications have not been shown to reduce mortality of patients with HFpEF, and an implantable cardioverter-defibrillator is not indicated due to normal ejection fraction. Sudden death is the most common mode of death in patients with HFpEF; however, the underlying mechanisms of sudden death are not fully elucidated. Although ventricular arrhythmias are responsible for the majority of sudden deaths in general, their contribution to sudden deaths in HFpEF patients is likely less significant. The mechanisms of ventricular arrhythmias in HFpEF are 1) reduced conduction velocity due to ventricular hypertrophy, 2) delayed repolarization due to potassium current down-regulation, 3) calcium leakage due to altered excitation-contraction coupling, and 4) increased ventricular fibrosis caused by systemic inflammation. Hypertension and subsequent ventricular hypertrophy reduce the conduction velocity in HFpEF hearts via heterogeneous distribution of connexin 43. Delayed repolarization caused by potassium current down-regulation in HFpEF hearts provides a window for early afterdepolarization to trigger ventricular arrhythmias. Altered excitation-contraction coupling in HFpEF can cause calcium to leak and trigger delayed afterdepolarization. Increased systemic inflammation and subsequent ventricular fibrosis provide substrates for re-entry. Further research is warranted to investigate the detailed mechanisms of ventricular arrhythmias in HFpEF.

• Food Science and Industry
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• v.51 no.2
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• pp.127-135
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• 2018

The action of antioxidants was different depending on the environments where antioxidants were located. Although basic mechanisms of lipid oxidation and antioxidants were related each other, their contribution on the degree of oxidation was different. In thisreview, terminology on antioxidant properties were defined such as antioxidant activity and antioxidant capacities. In addition, antioxidant mechanisms including primary and secondary antioxidants or hydrogen donating or electron transferring antioxidants were introduced. Also, the impact of physical points of view and antioxidant polar paradox were introduced. Depending on the types of food matrice including bulk oil, oil-in-water emulsion (O/W), or solid state, antioxidant actions showed different degree and this point was explained in detail.

• YAKHAK HOEJI
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• v.49 no.5
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• pp.386-391
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• 2005

The discovery of drugs for the treatment of mast cell-mediated allergic disease is a very important subject in human health. The Amomum xanthiodes (Zingiberaceae) has been used for centuries as a traditional medicine in Korea and is known to have an anti-inflammatory effect. However, its specific mechanism of action is still unknown. In this report, we investigated the effect of hot water extract from Amomum xanthiodes (EAX) on the mast cell-mediated allergic reaction and studied its possible mechanisms of action. EAX inhibited compound 48/80-induced systemic anaphylaxis and serum his­tamine release in mice. EAX decreased the passive cutaneous anaphylaxis reaction activated by anti-dinitrophenyl (DNP) IgE antibody. EAX dose-dependently reduced histamine release from rat peritoneal mast cells activated by compound 48/80 or anti-DNP IgE. EAX increased cAMP and decreased compound 48/80-induced intracellular $Ca^{2+}$ levels. Our findings provide evidence that EAX inhibits mast cell-derived allergic reactions, and also demonstrate the involvement of cAMP and intracellular $Ca^{2+}$ in these effects.

• Archives of Pharmacal Research
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• v.17 no.6
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• pp.405-410
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• 1994

The present study was undetertaken to demonstrate whether or not angiotensin II activates a phopholipase D in rabbit kidney proximal tubule cells. By measuring the formation of [$^3H$] phosphatidic acid and [$^3H$]diacylglycerol. This result suggests that some phosphatidic acid seems to be formed directly from phosphatidylcholin by the action of phopholipase D, not from the action of diacylglycerol kinase on the diacylglycerol. In addition the other mechanisms by which phospholipase D is activated was examined. We have found that phospholipase D was activited by extracellular calium ion. It has also been shown that angiotensin II may activate phosphoilpase D through protein kinase C-independent pathway.

• Journal of Microbiology and Biotechnology
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• v.33 no.3
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• pp.288-298
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• 2023

Host defense peptides are expressed in various immune cells, including phagocytic cells and epithelial cells. These peptides selectively alter innate immune pathways in response to infections by pathogens, such as bacteria, fungi, and viruses, and modify the subsequent adaptive immune environment. Consequently, they play a wide range of roles in both innate and adaptive immune responses. These peptides are of increasing importance due to their broad-spectrum antimicrobial activity and their functions as mediators linking innate and adaptive immune responses. This review focuses on the pleiotropic biological functions and related mechanisms of action of human host defense peptides and discusses their potential clinical applications.

• Biomolecules & Therapeutics
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• v.30 no.2
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• pp.117-125
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• 2022

Flavonoids are known to exert anti-inflammatory effects. Their pharmacological activities have been proved using various in vitro and in vivo models. Although their action spectrum and potencies are not adequate to alleviate acute inflammatory disorders, they have the potential to treat chronic inflammatory diseases. Recent investigations have revealed that inflammatory processes are involved in many disease processes and conditions. Some examples are skin disorders, cartilage diseases, metabolic inflammatory diseases, and aging. The effects of flavonoids on these disorders have been examined. Several possible application areas for flavonoids have been studied. Local treatment of these disorders with flavonoids is favorable to avoid systemic transformation. In this review, the findings based on the experimental results from my laboratory are summarized and the future possibility of using flavonoids clinically is discussed.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.265-283
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• 2021

To ensure that fire induced collapse of a building is prevented it is important to understand the sequence of events that can lead to this event. In this paper, the initiation of collapse mechanisms of generic a multi-storey steel frame subjected to vertical and horizontal travelling fires are analysed computationally by tracking the formation of plastic hinges in the frame and generation of fire induced loads. Both uniform and travelling fires are considered. In total 58 different cases are analysed using finite element software LS-DYNA. For the frame examined with a simple and generic structural arrangement and higher applied fire protection to the columns, the results indicate that collapse mechanisms for singe floor and multiple floor fires can be each split into two main groups. For single floor fires (taking place in the upper floors of the frame (Group S1)), collapse is initiated by the pull-in of external columns when heated beams in end bays go into catenary action. For single floor fires occurring on the lower floors(Group S2), failure is initiated (i.e. ultimate strain of the material is exceeded) after the local beam collapse. Failure in both groups for single floor fires is governed by the generation of high loads due to restrained thermal expansion and the loss of material strength. For multiple floor fires with a low number of fire floors (1 to 3) - Group M1, failure is dominated by the loss of material strength and collapse is mainly initiated by the pull-in of external columns. For the cases with a larger number of fire floors (5 to 10) - Group M2, failure is dominated by thermal expansion and collapse is mainly initiated by swaying of the frame to the side of fire origin. The results show that for the investigated frame initiation of collapse mechanisms are affected by the fire type, the number of fire floors, and the location of the fire floor. The findings of this study could be of use to designers of buildings when developing fire protection strategies for steel framed buildings where the potential for a multifloor fire exists.

• Journal of Photoscience
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• v.11 no.1
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• pp.11-17
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• 2004

Fluorescence quenching of l,4-bis [2-(2-methylphenyl) ethenyl]-benzene (Bis-MSB) by carbon tetrachloride in five different solvents namely hexane, cyclohexane, toluene, benzene and dioxane has been carried out at room temperature with a view to understand the quenching mechanisms. The Stern-Volmer plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the Ground state complex and Sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters imply that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation in the Stem-Volmer plots is attributed to the static and dynamic quenching. Further, with the use of Finite Sink approximation model, it was possible to check whether these bimolecular reactions as diffusion limited and to estimate independently distance parameter R' and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R'and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edwardis empirical relation and Stokes-Einstein relation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1180-1186
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• 1999

A wide ranges of chemicals released into the environment have potential to interfere with physiological and development process by disrupting endocrine pathways. Endocrine system embraces a multitude of mechanisms of action, including effect on growth, behavior, reproduction and immune function. These environmental endocrine disruptors are present in environment and pose potential health consequences to human and wildlife. The best known form in endocrine distruptors involves substances which mimic or block the action of natural hormone in the body. Endocrine disruptor have been variously defined as exogenous agents that interfere with the synthesis, secretion, transport, metabolism, binding action or elimination of the natural hormones in the body which are responsible for the maintenance of homeostasis, reproduction developmental and/or behavior. Many compounds polluted into the environment by human activity are capable of disrupting the endocrine system of animals, including fish, wildlife, and humans. Among these chemicals are pesticides, industrial chemicals, and other anthropogenic products. It has been alleged that several adverse effects on human health are linked with exposure to chemicals which are claimed to be endocrine disrupters, that is, increased incidence of testicular, prostate and female breast cancer, time dependent reductions in sperm quality and quantity, increased incidence of cryptorchidism (undescended testicles) and hypospadias(malformation of the penis), altered physical and mental de velopment in children. This observation is currently the only example of chemically mediated endocrine disruption which has resulted in a clear effect at the population level.