• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.137-144
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• 2011

Strengthening mechanisms in an ordered intermetallic compound containing coherent precipitates of lower antiphase boundary energy than the matrix were investigated on the basis of the interaction between the deformation induced dislocations and the disordered precipitates in an $Ll_2$ ordered $Ni_3Al$-based alloy. Extra work was needed to pull out the dislocations from the precipitate, which was dependent on the difference in the antiphase boundary energy between the matrix and the precipitate, as well as the size and volume fraction of the precipitate. The strength of the $Ll_2$ ordered ${\gamma}^{\prime}$ phase containing fine precipitates of the disordered ${\gamma}$ phase was examined using the proposed model. The model can explain almost quantitatively the age hardening behavior of the $Ll_2$ ordered ${\gamma}^{\prime}$ phase.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.3
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• pp.175-182
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• 2022

Translocation of azurophil granules is pivotal for bactericidal activity of neutrophils, the first-line defense cells against pathogens. Previously, we reported that lysophosphatidylcholine (LPC), an endogenous lipid, enhances bactericidal activity of human neutrophils via increasing translocation of azurophil granules. However, the precise mechanism of LPC-induced azurophil granule translocation was not fully understood. Treatment of neutrophil with LPC significantly increased CD63 (an azurophil granule marker) surface expression. Interestingly, cytochalasin B, an inhibitor of action polymerization, blocked LPC-induced CD63 surface expression. LPC increased F-actin polymerization. LPC-induced CD63 surface expression was inhibited by both a Rho specific inhibitor, Tat-C3 exoenzyme, and a Rho kinase (ROCK) inhibitor, Y27632 which also inhibited LPC-induced F-actin polymerization. LPC induced Rho-GTP activation. NSC23766, a Rac inhibitor, however, did not affect LPC-induced CD63 surface expression. Theses results suggest a novel regulatory mechanism for azurophil granule translocation where LPC induces translocation of azurophil granules via Rho/ROCK/F-actin polymerization pathway.

• Korean Journal of Biological Psychiatry
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• v.14 no.4
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• pp.221-231
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• 2007

Recent researches have shown that important cellular-based autoprotective mechanisms are mediated by heat-shock proteins(HSPs), also called 'molecular chaperones'. HSPs as molecular chaperones are the primary cellular defense mechanism against damage to the proteome, initiating refolding of denatured proteins and regulating degradation after severe protein damage. HSPs also modulate multiple events within apoptotic pathways to help sustain cell survival following damaging stimuli. HSPs are induced by almost every type of stresses including physical and psychological stresses. Our nervous system in the brain are more vulnerable to stress and damage than any other tissues due to HSPs insufficiency. The normal function of HSPs is a key factor for endogenous stress adaptation of neural tissues. HSPs play an important role in the process of neurodevelopment, neurodegeneration, and neuroendocrine regulation. The altered function of HSPs would be associated with the development of several neuropsychiatric disorders. Therefore, an understanding of HSPs activities could help to improve autoprotective mechanism of our neural system. This paper will review the literature related to the significance of HSPs in neuropsychiatric field.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.725-736
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• 2010

Nowadays, followed the internet service contents increasing makes also increase attack case on the web system. Usually web attack use mixed many kinds of attack mechanism for successfully attack to the server system. These increasing of the kinds attack mechanism, however web attack defence mechanism is not follow the spread of the attack. Therefore, for the defends web application, web attack should be categorizing and analysing for the effective defense. In this paper, we analyze web attack specification evidence and behavior system that use for effective expressions what we proposed. Also, we generate web attack scenario, it is for using verification of our proposed expressions.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.1
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• pp.31-36
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• 2015

As web accessibility has been easier, security issue becomes much more important in web applications demanding user authentication. Cookie is used to reduce the load of the server from the session in web applications and manage the user information efficiently. However, the cookie containing user information can be sniffed by an attacker. With this sniffed cookie, the attacker can retain the web application session of the lawful user as if the attacker is the lawful user. This kind of attack are called cookie replay attack and it causes serious security problems in web applications. In this paper, we have introduced a mechanism to detect cookie replay attacks and defend them, and verified effectiveness of the mechanism.

• Journal of Plant Biotechnology
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• v.32 no.2
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• pp.73-83
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• 2005

Disease resistance in plants is often controlled by gene-for-gene mechanism in which avirulence (avr) gene products encoding by pathogens are specifically recognized, either directly or indirectly by plant disease resistance (R) gene products and sequential signal transduction pathways activating defense responses are rapidly triggered. As a results, not only exhibit a resistance against invading pathogens but also plants maintain the systemic acquired resistance (SAR) to various other pathogens. This molecular interaction between pathogen and plant is commonly compared to innate immune system of animal. Recent studies arising from molecular characterization of a number of R genes from various plant species that confer resistance to different pathogens and corresponding avr genes from various pathogens resulted in the accumulation of a wealth of knowledge on molecular mechanism of gene-for-gene interaction. Furthermore, new technologies of genomics and proteomics make it possible to monitor the genome-wide gene regulation and protein modification during activation of disease resistance, expanding our ability to understand the plant immune response and develop new crops resistant to biotic stress.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2004.10a
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• pp.65-67
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• 2004

During initial interactions of bacteria with their host plants, most plants recognize the bacterial infections and repel the pathogen by plant defense mechanism. The most active plant defense mechanism is the hypersensitive response (HR) which is the localized induced cell death in the plant at the site of infection by a pathogen. A primary locus induced in gram-negative phytopathogenic bacteria during this initial interaction is the Hrp locus. The Hrp locus is composed of a cluster of genes that encodes the bacteral Type 111 machinery that is involved in the secretion and translocation of effector proteins to the plant cell. DNA sequence analysis of hrp gene in phytopathogenic bacteria has revealed a Hrp pathogenicity is]and (PAI) with a tripartite mosaic structure. For many gram-negative pathogenic bacteria, colonization of the host's tissue depends on the type III protein secretion system (TTSS) which secrets and translocates effector proteins into the host cell. Effectors can be divided into several groups including broad host range effectors, host specific effectors, disease specific effectors, and effectors inhibit host defenses. The role of effectors carrying LRR domain in plant resistance is very elusive since most known plant resistance gene carry LRR domain. Host specific effectors such as several avr gene products are involved in the determination of the host specificity. Almost all the phytopathogenic Xanthomonas spp. carry avrBs1, avrBs2, and avrBs3 homologs. Some strains of X. oryzae pv. oryzae carry more than 10 copies of avrBs3 homologs. However, the functions of all those avr genes in host specificity are not characterized well.;

• Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.14-21
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• 2006

The aim of this study was to investigate in vivo toxicity and effects of two phthalate esters (PEs), di-n-butylphthalate (DBP) and di-2-ethylhexyl phthalate (DEHP), on the immune system of the bagrid catfish, Pseudobagrus fulvidraco. Groups of experimental fish were subjected to daily intraperitoneal injections of 300 or 1000 mg $kg^{-1}$ of DBP or DEHP for 3 days, and the cellularity and functional activity of phagocytes were measured in the spleen and pronephros (head kidney). The number of spleen leukocyte cells increased significantly (p<0.05) in response to low and high doses of DEHP and DBP, respectively; however, the cellularity of the pronephros was more susceptible to higher dose of DEHP than DBP. Nonspecific immunity, as determined by the phagocytic index (PI) and phagocytic capacity (PC), was significantly depressed by DEHP at 1000 $1000mg\;kg^{-1}\;day^{-1}$ in the pronephros at 3 days after injection. Furthermore, significantly (p<0.05) increased levels of serum glutamic oxaloacetate transaminase (GOT) and glutamic pyruvate transaminase (GPT) indicated marked hepatic dysfunction in immunosuppressed fish. Treated fish showed a significant reduction in total serum protein but no significant alteration in lysozyme activity. These results demonstrate the sensitivity of the fish immune response for predicting PE-induced immunotoxicity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.8-19
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• 2010

In this paper, we propose the NCP (Network Control Platform)-based defense mechanism against DDoS (Distributed Denial of Service) attacks in order to guarantee the transmission of normal traffic and prevent the flood of abnormal traffic. We also define defense modules, the threshold and packet drop-rate used for the response against DDoS attacks. NCP analyzes whether DDoS attacks are occurred or not based on the flow and queue information collected from SR (Source Router) and VR (Victim Router). Attack packets are dopped according to drop rate decided from NCP. The performance is simulated using OPNET and evaluated in terms of the queue size of both SR and VR, the transmitted volumes of legitimate and attack packets at SR.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.4
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• pp.884-890
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• 2007

A mechanism of hair cell damage caused by noise and ototoxic agents is mediated through generation of free radicals and reactive oxygen species(ROS). It is known that most of animals have defense systems of ROS that protect against ROS, and the cochlea of animals also has ROS defense system, which appear efficient in detoxifying ROS generated under normal condition. This system includes several antioxidant enzymes such as superoxide dismutase(SOD), catalase(CAT), glutathione peroxidase (GPX), and glutathione reductase(GR). The radix of Pueraria thunbergiana(P. thunbergiana) is traditionally prescribed to attenuate the clinical manifestation of inner ear dysfunction and various clinical situations including fevers, gastrointestinal disorders, skin problems, migraine headaches, lowering cholesterol, and treating chronic alcoholism in Oriental Medicine. In the present study, to investigate the protection mechanism of ${\beta}-sitosterol$ from P. thunbergiana on cisplatin cytotoxicity toward HEI-OC1, we measured the effects of ${\beta}-sitosterol$ on activities of SOD, CAT, GPX, and GR in cisplatin treated cells. SOD, CAT, GPX, and GR activities were significantly increased in the presence of 0.001-0.1 ${\mu}g/ml$ of ${\beta}-sitosterol$ compared to the control group. These results indicate that ${\beta}-sitosterol$ protects cisplatin-induced HEI-OC1 cell damage through increasing the antioxidant enzyme system such as SOD, CAT, GPX, and GR.