• International Journal of Oral Biology
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• v.35 no.3
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• pp.129-135
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• 2010

Recent studies have implicated reactive oxygen species (ROS) as determinants of the pathological pain caused by the activation of peripheral neurons. It has not been elucidated, however, how ROS activate the primary sensory neurons in the pain pathway. In this study, calcium imaging was performed to investigate the effects of NaOCl, a ROS donor, on the intracellular calcium concentration ($[Ca^{2+}]i$) in acutely dissociated dorsal root ganglion (DRG) neurons. DRG was sequentially treated with 0.2 mg/ml of both protease and thermolysin, and single neurons were then obtained by mechanical dissociation. The administration of NaOCl then caused a reversible increase in the $[Ca^{2+}]i$, which was inhibited by pretreatment with phenyl-N-tertbuthylnitrone (PBN) and isoascorbate, both ROS scavengers. The NaOCl-induced $[Ca^{2+}]i$ increase was suppressed both in a calcium free solution and after depletion of the intracellular $Ca^{2+}$ pool by thapsigargin. Additionally, this increase was predominantly blocked by pretreatment with the transient receptor potential (TRP) antagonists, ruthenium red ($50\;{\mu}M$) and capsazepine ($10\;{\mu}M$). Collectively, these results suggest that an increase in the intracellular calcium concentration is produced from both extracellular fluid and the intracellular calcium store, and that TRP might be involved in the sensation of pain induced by ROS.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.41-47
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• 2012

The LDS(Laser Direct Structuring) is one of the new direct writing methods to fabricate conductive patterns by energy beam. It uses thermoplastic polymers with an additive compound that serves as plating seed after the activation by laser. The advantages of LDS include the miniaturization of electrical components, design flexibility, and a reduced number of production steps. The purpose of this study is to investigate the fundamental mechanism for LDS and the characteristics of conductive patterns by laser parameters. These results were studied by SEM, EDX, and XPS analysis. We have used a 20W pulse-modulated fiber laser and copper electroless plating to fabricate conductive patterns on polymer. The result showed that electroless copper plating seed caused the laser cracking of additive compound. In particular, the additive compound contained in copper metal oxides atoms will be changed to copper metal elements. Also, the characteristics of conductive patterns were dependent on laser parameter, especially laser fluence.

• Polymer(Korea)
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• v.26 no.3
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• pp.344-352
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• 2002

In this work, two thermal cationic latent catalysts, i.e., triphenyl benzyl phosphonium hexafluoroantimonate (TBPH) and benzyl 2-methylpyrazinium hexafluoroantimonate (BMPH) were newly synthesized. And the thermal and mechanical properties of difunctional epoxy (diglycidylether of bisphenol h, DGEBA) resins initiated by 1 phr of either TBPH or BMPH catalyst were investigated. As experimental results, the epoxy/TBPH system showed higher curing temperature and critical stress intensity factor ($K_{IC}$) than those of epoxy/BMPH. This could be interpreted in terms of slow thermal diffusion rate and bulk structure of four phenyl groups in TBPH. However, the decomposed activation energy determined from Coats-Redfern method was lower in the case of epoxy/TBPH. This result was probably due to the fact that broken short chain structure was developed by steric hindrance of TBPH.

• Journal of the Korean institute of surface engineering
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• v.43 no.6
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• pp.260-265
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• 2010

STD 61 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness, and creep strength as well as excellent oxidation resistance. The STD 61 tool steel coated with TiN and ZrN by sputtering results in improvement of wear and corrosion resistance. In this study, surface characteristics of TiN and ZrN film coated STD 61 by sputtering were studied by using FE-SEM, EDS, XRD, and XRR and nanoindentation tests. From the results of surface characteristics of coated specimen, the ZrN coated surface showed finer granular than that of TiN coated surface. The coated layer structures of ZrN and TiN were grown to (111) and (200) preferred orientation. From the results of XRR test for surface roughness, density and growth rate of coating film, surface roughness and growth rate of ZrN coated film revealed lower values those of TiN coated film, whereas density of ZrN coated film showed higher values than that of TiN coated film. From the nanohardness and elastic modulus test, nanohardness value and elastic modulus of ZrN coated film became higher than those of TiN coated film.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.93-94
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• 2011

This paper analyzes the shaft torsion of a doubly-fed induction generator (DFIG) for a wind farm collector system fault. When a fault occurs, the active power of the DFIG cannot be transmitted to the grid and thus accelerates the rotation of both the blade and the rotor. Due to the different inertia of these, the angle of deviation fluctuates and the shaft torsion is occurred. This becomes much severe when the rotational speed of the blade exceeds a threshold, which activating the pitch control to reduce the mechanical power. The torque, which can be sixty times larger than that in the steady state, may destroy the shaft. The shaft torsion phenomena are simulated using the EMTP-RV simulator. The results indicate that when a wind farm collector system fault occurs, a severe shaft torsion is occurred due to the activation of the pitch control.

• Journal of Korean Society for Quality Management
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• v.28 no.4
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• pp.16-28
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• 2000

Recently days, High Accelerated Life Test of electrical and electronic parts is increasing its importance. This study set the hypothesis to develop the method that was analysis and application of HALT for the automotive electrical and electronic parts, it used Arrhenius's Model and Eyring's Model, and ESS theory. Validity of application is proved by other test data. Especially, this study emphasis on utility of acceleration to temperature, humidity, voltage, mechanical stress and other stress. In this study set the pattem of practical application. Therefore, this study emphasis on the application of the HALT and the use of other parameter by acceleration reliability test data. The result of this study is as follows. 1) There is relationship between molar weight and material constant. 2) Characteristic of material is operating acceleration factor as well as parts failure factors. Of course, according to the characteristic of material, activation energy is often more important than molar weight. But it will be defined by more testing and improvements in practical application.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.2
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• pp.63-70
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• 2002

Cholinergic modulation of GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) by the activation of muscarine receptors was investigated in mechanically dissociated rat nucleus basalis of the Meynert neurons using the conventional whole-cell patch recording configuration. Muscarine $(10{\mu}M)$ reversibly and concentration-dependently decreased mIPSC frequency without affecting the current amplitude distribution. Muscarine action on GABAergic mIPSCs was completely blocked by $1{\mu}M$ methoctramine, a selective $M_2$ receptor antagonist, but not by $1{\mu}M$ pirenzepine, a selective $M_1$ receptor antagonist. NEM $(10{\mu}M),$ a G-protein uncoupler, attenuated the inhibitory action of muscarine on GABAergic mIPSC frequency. Muscarine still could decrease GABAergic mIPSC frequency even in the $Ca^{2+}-free$ external solution. However, the inhibitory action of muscarine on GABAergic mIPSCs was completely occluded in the presence of forskolin. The results suggest that muscarine acts presynaptically and reduces the probability of spontaneous GABA release, and that such muscarine-induced inhibitory action seems to be mediated by G-protein-coupled $M_2$ receptors, via the reduction of cAMP production. Accordingly, $M_2$ receptor-mediated disinhibition of nBM neurons might play one of important roles in the regulation of cholinergic outputs from nBM neurons as well as the excitability of nBM neurons themselves.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.791-797
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• 2003

The special binding mechanism developed provides higher density, lower porosity and higher strengths compared with conventional castables. $\rho$-alumina was employed as a binder materials and nano-sized clay colloidal was added to enhance the drying strength preparing for the alumina vibrated castable. Lower water requirement for casting results in a denser product. The mechanical properties with dimensional stability and corrosion resistance behaviors have been improved by controlling the matrix compositions of the castable. The modulus of rupture and compressive strength after heat treatment at 150$0^{\circ}C$ are 92.34 kgf/$\textrm{cm}^2$ and 370 kgf/$\textrm{cm}^2$ respectively. The activation energy of mullite formation is 11.47 kcal/mol.

• Toxicological Research
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• v.18 no.2
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• pp.183-190
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• 2002

The mechanism by which catechin-mediated cytotoxicity against tumor cells remains to be elusive. To elucidate the mechanical mights of anti-tumor effects, (-)epigallocatechin-gallate (EGCG) of catechin was applied to human prostate cancer DU 145 cells. Cell viability was measured by crystal violet staining. Cell lysates were wed to measure the catalytic activity of caspases by using fluorogenic peptide: Ac-DEVD-AMC for caspase-3 protease, Z-IETD-AFC for caspase-8 protease, Ac-LEHD-AFC for caspase-9 protease as substrates. The equal amounts of protein from cell lysate was separated on SDS-PAGE and analyzed by western blotting with anti-Fas antibody, anti-FasL antibody, anti-BCL2 antibody and anti-Bax antibody. (-)EGCG induced the death of DUl45 cells, which was revealed as apoptosis shown by DNA fragmentation. (-)EGCG induced the activation of caspase family cysteine proteases including caspase-3, -8 and -9 proteases in DU145 cells. Also, (-)EGCG increased the expression of Fas and Fas ligand (FasL) protein in DU145 colls. The expression level of BCL2 was decreased in (-)EGCG treated DU145 cells, whereas Bax protein was increased in a time-dependent manner. We suggest that (-)EGCG-induced apoptosis of DU145 cells is mediated by signaling pathway involving caspase family cysteine protease, mitochondrial BCL2-family protein and Fas/FasL.

• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.255-267
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• 2018

Inflammation is one of the main causes of pathologic pain. Knowledge of the molecular links between inflammatory signals and pain-mediating neuronal signals is essential for understanding the mechanisms behind pain exacerbation. Some inflammatory mediators directly modulate the excitability of pain-mediating neurons by contacting the receptor molecules expressed in those neurons. For decades, many discoveries have accumulated regarding intraneuronal signals from receptor activation through electrical depolarization for bradykinin, a major inflammatory mediator that is able to both excite and sensitize pain-mediating nociceptor neurons. Here, we focus on the final effectors of depolarization, the neuronal ion channels, whose functionalities are specifically affected by bradykinin stimulation. Particular G-protein coupled signaling cascades specialized for each specific depolarizer ion channels are summarized. Some of these ion channels not only serve as downstream effectors but also play critical roles in relaying specific pain modalities such as thermal or mechanical pain. Accordingly, specific pain phenotypes altered by bradykinin stimulation are also discussed. Some members of the effector ion channels are both activated and sensitized by bradykinin-induced neuronal signaling, while others only sensitized or inhibited, which are also introduced. The present overview of the effect of bradykinin on nociceptor neuronal excitability at the molecular level may contribute to better understanding of an important aspect of inflammatory pain and help future design of further research on the components involved and pain modulating strategies.