• KSCE Journal of Civil and Environmental Engineering Research
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• 제32권1A호
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• pp.11-18
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• 2012

This paper deals with the numerical determination of the stress intensity factors of cracked aluminum plates under the mixed mode of $K_I$ and $K_{II}$ in glass-epoxy fiber reinforced composites. For the stress intensity factors, two different models are reviewed such as VCCT and two-step extension method. The p-convergent partial layerwise model is adopted to determine the fracture parameters in terms of energy release rates and stress intensity factors. The p-convergent approach is based on the concept of subparametric element. In assumed displacement field, strain-displacement relations and 3-D constitutive equations of a layer are obtained by combination of 2-D and 1-D higher-order shape functions. In the elements, Lobatto shape functions and Gauss-Lobatto technique are employed to interpolate displacement fields and to implement numerical quadrature. Using the models and techniques considered, effects of composite laminate configuration according to inclined angles and adhesive properties on the performance of bonded composite patch are investigated. In addition to these, the out-of-plane bending effect has been investigated across the thickness of patch repaired laminate plates due to the change of neutral axis. The present model provides accuracy and simplicity in terms of stress intensity factors, stress distribution, number of degrees of freedom, and energy release rates as compared with previous works in literatures.

• Journal of Korea Society of Industrial Information Systems
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• 제18권5호
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• pp.81-92
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• 2013

The satellite includes many release mechanisms such as solar array deployment, antenna deployment, cover to protect contamination in scientific equipment, pyro value of the propulsion subsytem, and bypass device in Li-Ion cell module. A drive the initiators is a critical to the successful mission because the initiators of release mechanism driving by the pyrotechnic circuit is operated in single short. The pyrotechnic circuit has to provide switching network for safety. A typical switching network has defect consisting of high current rating fire switch to handle switching transient current during fire the initiator. The pyrotechnic circuit is required some form of power conditioning to reduce the peak power demanded from the bus if the initiators are to be fired from the main bus. This paper design a pyrotechnic circuit synchronized to the fire-command to activate the fire switch to overcome use high current rating fire switch to handle switching transient current during fire the initiator. The pyrotechnic circuit provides a current limited widow pulse for fire current synchronized to the fire-command to insure that fire switch will only carry the current but never switch it. The current limited widow pulse for fire current can be possible to use low current rating and light mass switch in switching network. The current limit function in the pyrotechnic circuit reduces supply voltage to initiator and provides the effect of power conditioning function to reduce peak bus power. The pyrotechnic circuit to apply satellite development on geostationary orbit is verified the function by test in development model.

• Journal of Life Science
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• 제21권10호
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• pp.1364-1369
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• 2011

Mast cells, the central effector cells involved in the allergic response, release histamine, arachidonic acid, and proinflammatory cytokines. We investigated the effect of the ethyl acetate fraction (EA), derived from Korean rice wine lees, on RBL-2H3 cell degranulation and passive cutaneous anaphylaxis in an animal model. The EA fraction suppressed the release of beta-hexosaminidase, a marker of degranulation, and the mRNA expression of interleukin-3 (IL-3) and IL-13. EA also successfully suppressed the passive cutaneous anaphylaxis (PCA) reaction in mice in a dose-dependent manner. These results suggest that EA can inhibit mast cell degranulation through the inhibition of IL-3 and IL-13 mRNA expression, and that EA may potentially serve as an anti-allergic agent.

• The korean journal of orthodontics
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• 제33권6호
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• pp.453-463
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• 2003

Mammalian cell is critically dependent on a continuous supply of oxygen. Even brief periods of oxygen deprivation can result in profound cellular damage. The aim of this study was to examine the possible mechanism of apoptosis in response to hypoxia in MC3T3E1 osteoblasts. MC3T3El osteoblasts under hypoxic conditions ($2\%$ oxygen) resulted in apoptosis in a time-dependent manner, determined by DNA fragmentation assay and nuclear morphology, stained with fluorescent dye (Hoechst 33258) Pretreatment with Z-VAD-FMK, a pancaspase inhibitor, or Z-DEVD-CHO, a specific caspase-3 inhibitor, suppressed the DNA ladder in response to hypoxia in a concentration dependent manner. An increase in caspase-3-like protease (DEVDase) activity was observed during apoptosis, but no caspase-l activity (YVADase) was detected. To confirm what caspases were involved in apoptosis, western blot analysis was performed using an anticaspase-3 or 6 antibody. The 17-kDa protein, that corresponds to the active products of caspase-3 and the 20-kDa protein of the active protein of caspase-6 were generated in hypoxia-challenged lysates, in which the full length forms of caspase-3 and 6 were evident. With a time course similar to caspase-3 and 6 activation, hypoxic stress also caused the cleavage of Lamin A, typical of caspase-6 activity. In addition, the hypoxic stress elicited the release of cytochrome c into the cytosol during apoptosis. These findings suggested that the activation of caspases accompanied by a cytochrome c release in response to hypoxia was involved in apoptotic cell death in MC3T3E1 osteoblasts.

• Journal of Periodontal and Implant Science
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• 제29권3호
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• pp.507-519
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• 1999

The ultimate objective of periodontal treatment is to stop disease progression and to regenerate destroyed periodontal tissues and thereby regain normal function. Growth factors are naturally found polypetides which stimulate many cellular activities pertaining to wound healing by acting as signal molecule in controlling cell movement, proliferation, and matrix production. Platelet derived growth factor (PDGF) is 28,000-35,000 Da molecular weight dimeric protein with 2 long positively charged polypeptide chains connected by sulfide bonds. The purpose of this study is to evaluate histologically the initial guided tissue regeneration in a periodontal defect f a beagle dog treated with a biodegradable membrane formed with polylactic acid (poly-L-lactic acid) and polyglycolic acid loaded with 200ng/$cm^2$ platelet derived growth factor. 2 beagle dogs were used in he experiment. $5mm{\times}6mm$ alveolar bone defect was formed in upper and lower canines and third premolars and a reference notch was placed. PDGF-BB non-containing membrane was used as control. Each defect was randomly assigned to the test roup or the control group. The dogs were sacrificed 3 weeks after membrane placement. Toluidine blue and multiple staining was done for histological analysis. In the 3 week specimen in the control group, no new one formation could be seen. Small amount f bone resorption below the notch could be seen. In the notch, loose connective tissue with infiltration of inflammatory cells could be seen. Also thin discontinuous new cementum could be seen and the membrane still retained its structure. Where PDGF-BB containing membrane was used, new bone formation could be seen in the notch at weeks and also continuous thin cementum could be seen. PDL cells were observed between new bone and new cementum and some were attached to bone and cementum. These results suggest that new bone and cementum formation seen when PDGF-BB loaded membrane was used was due to inhibition of downgrowth of epithelial cells and also due to continuous release of the growth factor. Further study on the resorption characteristics of the membrane nd the release characteristics of the PDGF-BB is necessary. Also, development of a membrane easier to use clinically is necessary.

• Korean Journal of Clinical Laboratory Science
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• 제47권4호
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• pp.230-236
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• 2015

Dermatophagoides pteronissinus (DP) is one of the house dust mites (HDM) associated with allergic diseases. The cysteine protease Der p 1 from DP is a powerful allergen. The pathogenic mechanism of allergy is involved in cytokine secretion of lymphocytes and spontaneous apoptosis of neutrophils. In this study, we investigated whether Der p 1 induces cytokine secretion of lymphocytes and if the release of cytokines is associated with regulation of neutrophil apoptosis. In normal and allergic subjects, Der p 1 increased IL-6, IL-8, MCP-1, and GM-CSF release in a time-dependent course. Supernatants collected from normal and allergic neutrophils after Der p 1 stimulation suppressed the apoptosis of normal and allergic neutrophils, although Der p 1 alone has no effect on neutrophils. Der p 1 suppressed neutrophil apoptosis in coculture of normal neutrophils with normal lymphocytes. Der p 1 more strongly suppressed apoptosis of allergic neutrophils cocultured with allergic lymphocytes than normal neutrophils cocultured with normal lymphocytes. In summary, Der p 1 increases the secretion of cytokines, which has anti-apoptotic effects on neutrophils of normal and allergic subjects. These results will contribute to elucidate the pathogenic mechanism of allergic diseases.

• Fire Science and Engineering
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• 제27권6호
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• pp.50-56
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• 2013

The radiation effects on the auto-ignition and extinction characteristics of a non-premixed fuel-air counterflow field were numerically investigated. A detailed reaction mechanism of GRI-v3.0 was used for the calculation of chemical reactions and the optically-thin radiation model was adopted in the simulations. The flame-controlling continuation method was also used in the simulation to predict the auto-ignition point and extinction limits precisely. As a result, it was found that the maximum H radical concentration, $(Y_H)_{max}$, rather than the maximum temperature was suitable to understand the ignition and extinction behaviors. S-, C- and O-curves, which were well known from the previous theory, were identified by investigating the $(Y_H)_{max}$. The radiative heat loss fraction ($f_r$) and spatially-integrated heat release rate (IHRR) were introduced to grasp each extinction mechanism. It was also found that the $f_r$ was the highest at the radiative extinction limit. At the flame stretch extinction limit, the flame was extinguished due to the conductive heat loss which attributed to the high strain rate although the heat release rate was the highest. The radiation affected on the radiative extinction limit and auto-ignition point considerably, however the effect on the flame stretch extinction limit was negligible. A stable flame regime defined by the region between each extinction limit became wide with increasing the fuel temperature.

• Korean Journal of Biological Psychiatry
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• 제6권2호
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• pp.193-201
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• 1999

This study was designed to evaluate the effects of opioid receptor agonists on the spontaneous alternation behaviour in an animal model of obsessivecompulsive disorder in rats. According to the theory that dopamine is related to the biological etiology of obsessive-compulsive disorder, the effect of the nalbuphine(opioid kappa agonist) and the tramadol(opioid mu agonist), which act as manipulating agents on the inhibition or stimulation of dopamine release, in the spontaneous alternation behaviour were evaluated. 24 hours prior to the experiment, rats were food-deprived. These rats were put into the T-maze, in which white and black goal boxes were baited with small amounts of chocolate milk. Each rat was given 2 set of 7 trials during which it was placed in the start box and allowed to choose the one of the goal boxes for each time. After identifying the stable baseline of spontaneous alternation behaviour, nonselective 5-HT agonist 5-MeODMT(1.25mg/kg/IP) disrupted spontaneous alternation. Rats were stratified into fluoxetine(10mg/kg/IP), nalbuphine(10mg/kg/IP), tramadol(46.4mg/kg/IP), and saline(0.5cc/IP) injection group with experimental drug treatment for 21 days. The effects on the 5-MeODMT(1.25mg/kg/IP) induced disruption of spontaneous alternation behaviour were checked at the next day of discontinuation of drug treatment. The results were as follows ; 1) At the day after 21 days of the drug treatment, the nalbuphine treated group and the fluoxetine treated group showed significant difference from the tramadol treated group and the saline treated group in the 5-MeODMT(1.25mg/kg/IP) induced suppression of spontaneous alternation behaviour. 2) Within each drug treatment group, the fluoxetine treated group showed significant difference between before and after the treatment of fluoxetine in the 5-MeODMT(1.25mg/kg/IP) induced suppression of spontaneous alternation behaviour. And also, the nalbuphine treated group showed significant difference between before and after the treatment of nalbuphine in the 5-MeODMT(1.25mg/kg/IP) induced suppression of spontaneous alternation behaviour. There was no difference between the baseline and after the treatment of nalbuphine in the 5-MeODMT(1.25mg/kg/IP) induced suppression of spontaneous alternation behaviour. We indentified that the opioid kappa agonist that act as dopamine release inhibitor affect the spontaneous alternation behaviour which is an animal model of obsessive-compulsive disorder in rat.

• Journal of Chest Surgery
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• 제33권5호
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• pp.398-406
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• 2000

Background: Cardiac atrium is an endocrine gland secreting a family of natriuretic peptides. The secretion of atrial natriuretic peptide(ANP) had been shown to be controlled by variable factors. The change in atrial dynamics have been considered as one of the most prominent stimuli for the stimulation of ANP secretion. Hypoxic stress has been shown to increase cardiac ANP secretion. However, the mechanism by which hypoxia increases ANP secretion cardiac ANP secretions. However, the mechanism by which hypoxia increases ANP secretion has not to be defined. Therefore, the purpose of the present study was tow-fold: to develop a protocol to defined the effect of hypoxia on ANP secretion in perfused beating rabbit atria and to clarify the mechanism responsible for the accentuation by hypoxia of ANP secretion. Material and Method: Experiments have been done in perfused beating rabbit atria. ANP was measured by radioimmunoassay. Result: Hypoxic stimulus with nitrogen decreased atrial stroke volume. The decrease in atrial stroke volume recovered basal level during the period of recovery with oxygen. ANP secretion and the concentration of perfusate ANP in terms of extracellular fluid(ECF) translocation which reflects the rate of myocytic release of ANP were increased by hypoxia and returned to basal levels during the recovery. Changes in ECF translocation paralleled by hypoxia and returned to basal levels during the recovery. Changes in ECF translocation paralleled to that of atrial stroke volume. At the start of recovery in atrial storke volume, ECF tranalocation incrased for several minutes. The above responses were stable and reproducible. Glibenclamide treatment prevented the recovery in atrial stroke volume. Increments by hypoxia of ANP secretion and ANP concentration were suppressed by glibenclamide. Conclusion: These results indicate that hypoxia incrased atrial myocytic ANP release and that the mechanism responsible for the accentuation is partially related to the change in K+ATP channel activity.

• Journal of Korean Neurosurgical Society
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• 제30권4호
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• pp.417-424
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• 2001

Objective : Adrenal medullary chromaffin cells are known to release analgesic substances such as opioides and catecholamines. Transplantation of them is a novel method that challenges current approaches in treating chronic pain. The transplantation of xenogeneic chromaffin cells into the central nervous system(CNS) supply antinociception in animals. In this study, we investigated the analgesic effects of rat adrenal medullary chromaffin cells transplanted into the CNS of the mouse. To study the antinociceptive efficacy of transplanted chromaffin cells, the survival of rat adrenal medullary chromaffin cells transplanted into the CNS of mouse was determined. Methods : The adrenal medullary chromaffin cells isolated from rat were transplanted into the striatum of mouse. These cells were confirmed of the release of Met-enkephalin and Leu-enkephalin by HPLC, and immunoblots for tyrosine hydroxylase(TH). Two weeks after transplantation, we performed immunohistochemistry for TH to determine the survival of implanted cells and assessed pain sensitivity at the same time. Results : The isolated rat adrenal medullary chromaffin cells were positive for anti-TH antibody and released Met-enkephalin and Leu-enkephalin more than rat endothelial cells. Transplanted rat chromaffin cells were stained with anti-TH antibody in striatum of mouse after 2 weeks. Pain sensitivity was reduced on the chromaffin cell-transplanted mouse compared to endothelial cell-transplanted mouse by the hot plate test. Conclusion : These results suggest that the rat chromaffin cells were suitably transplanted into the CNS of mouse. This approach could be used as a therapy for reducing of chronic pain induced by cancer or neuronal injury.