• Yonsei Medical Journal
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• v.59 no.9
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• pp.1079-1087
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• 2018

Purpose: Obstructive sleep apnea and chronic obstructive pulmonary disease are independent risk factors of cardiovascular disease (CVD), and their coexistence is known as overlap syndrome (OS). Endothelial dysfunction is the initial stage of CVD; however, underlying mechanisms linking OS and CVD are not well understood. The aim of this study was to explore whether OS can lead to more severe inflammation and endothelial apoptosis by promoting endothelial dysfunction, and to assess the intervention effects of antioxidant tempol. Materials and Methods: Male Wistar rats (n=66) were exposed to normal oxygen [normal control (NC) group], intermittent hypoxia (IH group), cigarette smoke (CH group), as well as cigarette smoke and IH (OS group). Tempol intervention was assessed in OS group treated with tempol (OST group) or NaCl (OSN group). After an 8-week challenge, lung tissues, serum, and fresh blood were harvested for analysis of endothelial markers and apoptosis. Results: The levels of intracellular adhesion molecule-1, vascular cellular adhesion molecule-1, and apoptosis in circulating epithelial cells were the highest in OS group and the lowest in NC group. These levels were all greater in IH group than in CH group, and were lower in OST group than in OS and OSN groups (all p<0.001). Conclusion: Synergistic effects of IH with cigarette smoke-induced emphysema produce a greater inflammatory status and endothelial apoptosis. OS-related inflammation and endothelial cell apoptosis may play important roles in promoting cardiovascular dysfunction, and antioxidant tempol could achieve a partial protective effect.

• Journal of the Korean Electrochemical Society
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• v.21 no.3
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• pp.47-54
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• 2018

To maximize the areal capacity($mAh\;cm^{-2}$) of $LiNi_{0.5}Co_{0.2}Mn_{0.3}O_2$(NCM523) electrode with the same loading level of $15mg\;cm^{-2}$, three NCM523 electrodes with 4, 2, and 1 wt% poly(vinylidene fluoride)(PVdF) binder content are fabricated. Due to the delamination issue of electrode composite at the edge during punching process, the 1 wt% electrode is excluded for further evaluation. When the PVdF binder content decreases from 4 to 2 wt%, both adhesion strength and shear stress decrease from 0.4846 to $0.2627kN\;m^{-1}$ by -46% and from 3.847 to 2.013 MPa by -48%, respectively. Regardless of these substantial decline of mechanical properties, their initial electrochemical properties such as initial coulombic efficiency and voltage profile are almost the same. However, owing to high loading level, the 2 wt% electrode not only exhibits worse cycle performance than the 4 wt% electrode, but also cannot maintain its mechanical integrity only after 80 cycles. Therefore, if the binder content is reduced to increase the area capacity, the mechanical properties as well as the cycle performance must be carefully evaluated.

• Journal of Chest Surgery
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• v.33 no.3
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• pp.213-220
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• 2000

Background: Adhesion of leukocytes to myocardium or vascular endothelium has been known as an importation initial step in the ischemia-reperfusion injury which may affect the cardiac function. Therefore, leukocyte-depleted reperfusion may inhibit ischemia-reperfusion induced functional and ultrastructural deterioration. In this study, we quantified the time-dependent expression of the vascular cell adhesion molecule-1(VCMA-1) on piglet myocardium and demonstrated its relation to functional recovery using isolated piglet heart perfusion model. Material and Method: Neonatal(1 to 3 day old) piglet heart was harvested with 4$^{\circ}C$ University of Wisconsin solution (UWS) and presrved in the same solution for 12 hours. Ex vivo model of an isolated working neonatal piglet heart perfusion consisting of membrane oxygenator and roller-pump was used (Fig. 1). Hearts were grouped into leukocyte-non-depleted (group A, n=8) and leukocyte-depleted group(group B, n=8). In group B, hearts were reperfused with leukocyte-depleted blood using a leukocyte filter (Sepacell R, Asahi Medical, Japan). Segments of right atrium were taken before and after 1, 2, 3, and 4 hours of reperfusion for the evaluation of expression of VCAM-1. The intensity of immunohistochyemical satining of the VCAM-1 on the myocardium were graded semiquantitatively (0 to 4). For the evaluation of myocardial stroke work indices were calculated as well at the same time-points. Result: Mean expressins of VCAM-1 on the myocardium at 0, 1, 2, 3, adn 4 hours of reperfusion were 0.63, 1.44, 1.64, 2.65, and 3.34 in group A, while 0.56, 1.40, 1.50, 1.88 and 2.14 in group B (Fig. 3). Mean stroke work indices at 0.5, 1, 2, 3, and 4 hours after reperfusion were 1.35$\times$104, 1.32$\times$104, 1.14$\times$104, 0.81$\times$104, 0.68$\times$104 erg/gm in group A, while 1.40$\times$104, 1.43$\times$104, 1.43$\times$104, 1.28$\times$104, and 1.12$\times$104 erg/em in group B(Fig. 4). Conclusion : In this study, we demonstrated that leukocyte-depletion attenuated the expression of VCAM-1 during reperfusion and the time-dependent functional deterioration of the myocardium was well correlated with the degree of VCAM-1 expression.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.2
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• pp.114-121
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• 2020

Objective: Despite extensive research on implantation failure, little is known about the molecular mechanisms underlying the crosstalk between the embryo and the maternal endometrium, which is critical for successful pregnancy. Profilin 1 (PFN1), which is expressed both in the embryo and in the endometrial epithelium, acts as a potent regulator of actin polymerization and the cytoskeletal network. In this study, we identified the specific role of endometrial PFN1 during embryo implantation. Methods: Morphological alterations depending on the status of PFN1 expression were assessed in PFN1-depleted or control cells grown on Matrigel-coated cover glass. Day-5 mouse embryos were cocultured with Ishikawa cells. Comparisons of the rates of F-actin formation and embryo attachment were performed by measuring the stability of the attached embryo onto PFN1-depleted or control cells. Results: Depletion of PFN1 in endometrial epithelial cells induced a significant reduction in cell-cell adhesion displaying less formation of colonies and a more circular cell shape. Mouse embryos co-cultured with PFN1-depleted cells failed to form actin cytoskeletal networks, whereas more F-actin formation in the direction of surrounding PFN1-intact endometrial epithelial cells was detected. Furthermore, significantly lower embryo attachment stability was observed in PFN1-depleted cells than in control cells. This may have been due to reduced endometrial receptivity caused by impaired actin cytoskeletal networks associated with PFN1 deficiency. Conclusion: These observations definitively demonstrate an important role of PFN1 in mediating cell-cell adhesion during the initial stage of embryo implantation and suggest a potential therapeutic target or novel biomarker for patients suffering from implantation failure.

• Journal of Korean Neurosurgical Society
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• v.29 no.7
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• pp.929-934
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• 2000

Objective : The results of secondary transsphenoidal surgery(TSS) for either residual or recurring pituitary adenomas have been reported to be unfavorable. To evaluate the effectiveness of secondary TSS, we analyzed the surgical results of residual or recurred pituitary adenomas in patients who underwent secondary TSS from 1992 to 1998. Material and Methods : Among the 95 patients who underwent TSS during this period, 14(15%) received repeated TSS. Two of the 14 patients underwent three TSS. Among the 11 patients with pituitary adenomas, three had nonfunctioning tumors ; six prolachnomas ; two GH-secreting adenomas. The remaining three patieats had craniopharyngioma, pituitary abscess and hemangioendothelioma respectively. The interval between the two surgical procedures ranged from one week to 33 months(mean ; 12 months). Causes of the secondary TSS were tumor recurrence in 11 patients, intentional staged operation in three, persistent disease despite medical therapy and CSF leak after initial operation in one respectively. Treatments prior to secondary TSS were medical treatment only in eight patients. Results : During the repeated operationtss some adhesion was noted in septal mucous membrane. The sphenoid cavity was filled with fibrous tissue which correlated with the methods of reconstruction of the sellar floor at the previous operation. There was no statistically significant difference in success rate of surgery between the initial and the second TSS(86% vs 81%). The complication rate was similar between the two procedures. There was no statistically significant factors affecting the results of second TSS. Conclusion : Transsphenoidal reoperation was regarded as a suitable approach for treating recurrent pituitary adenomas in spite of some degree of operative difficulties. In patients with transsphenoidally resectable tumor residuals or recurrences confirmed by magnetic resonance imaging, remissions can be obtained with high probability, especially in secondary surgery after an staged decompression.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.21-27
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• 2011

A nano-porous structure of tin oxide was prepared using an anodic oxidation process and the sample's electrochemical properties were evaluated for application as an anode in a rechargeable lithium battery. Microscopic images of the as-anodized sample indicated that it has a nano-porous structure with an average pore size of several tens of nanometers and a pore wall size of about 10 nanometers; the structural/compositional analyses proved that it is amorphous stannous oxide (SnO). The powder form of the as-anodized specimen was satisfactorily lithiated and delithiated as the anode in a lithium battery. Furthermore, it showed high initial reversible capacity and superior rate performance when compared to previous fabrication attempts. Its excellent electrode performance is probably due to the effective alleviation of strain arising from a cycling-induced large volume change and the short diffusion length of lithium through the nano-structured sample. To further enhance the rate performance, the attempt was made to create porous tin oxide film on copper substrate by anodizing the electrodeposited tin. Nevertheless, the full anodization of tin film on a copper substrate led to the mechanical disintegration of the anodic tin oxide, due most likely to the vigorous gas evolution and the surface oxidation of copper substrate. The adhesion of anodic tin oxide to the substrate, together with the initial reversibility and cycling stability, needs to be further improved for its application to high-power electrode materials in lithium batteries.

• Elastomers and Composites
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• v.52 no.1
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• pp.22-26
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• 2017

The thermal conductivity and the adhesive properties were measured, after synthesis of thermal conductive composite which was obtained as a result of mixing alumina or graphite with acrylic adhesive synthesized by UV polymerization. The adhesive properties of the composite were evaluated measuring the peel strength at 180 degrees, the retention, and the initial tack;the thermal conductivity was estimated using laser flash analysis. As the filler contents increased, a decrease in peel strength and initial tack and an increase in retention and thermal conductivity were observed. When compared to alumina, the adhesion of graphite showed a dramatic decrease, whereas the thermal conductivity was further enhanced. It was found out that the small size of graphite increased the mechanical interlocking between the polymer and the filler, and it was easier for graphite to come into contact with other graphite in the matrix.

• International Journal of Concrete Structures and Materials
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• v.18 no.1E
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• pp.29-34
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• 2006

Elastic modulus, tensile and bond capacities are important factors for developing an effective reinforcing action of a flexural member as a reinforcing material for concrete structures. Reinforcement must have enough bond capacity to prevent the relative slip between concrete and reinforcement. This paper presents an experimental study to clarify the bond capacity of prestressed carbon fiber reinforced polymer(CFRP) rod manufactured by an automatic assembly robot. The bond characteristics of CFRP rods with different pitch of helical wrapping were analyzed experimentally. As the result, all types of CFRP rods show a high initial stiffness and good ductility. The mechanical properties of helical wrapping of the CFRP rods have an important effect on the bond of these rods to concrete after the bond stress reached the yield point. The stress-slip relationship analyzed from the pull-out test of embedded cables within concrete was linear up to maximum bond capacity. The deformation within the range of maximum force seems very low and was reached after approximately 1 mm. The average bond capacity of CF20, CF30 and CF40 was about 12.06 MPa, 12.68 MPa and 12.30 MPa, respectively. It was found that helical wrapping was sufficient to yield bond strengths comparable to that of steel bars.

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.168-172
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• 2013

This work presents the effects of binders on the electrochemical performance of Si-C composites as the anode of lithium ion batteries. PAI (polyamide-imide) was used as an organic binder, and PAN (polyacrylonitrile), PAA (polyacrylic acid) and CMC + SBR (carboxymethyl cellulose + styrene-butadiene rubber) were used as aqueous binders. As a result, stabilization time for the cell with a Si-C composite anode synthesized using aqueous binders became shorter than an organic binder. Particularly in the case of the cell using PAA binder, better performance was observed in terms of adhesion strength, initial efficiency, the volume expansion ratio, Coulombic efficiency, and capacity retention.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.13-16
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• 2005

Generally, as corrosive protection processing of a steel structure, zinc galvanizing and heavy duty coating paint are applied. However, zinc galvanizing has the difficulty of restriction of a size, or on-site construction. Moreover, heavy duty coating paint has a problem with many administrative and maintenance expenses with short problem of adhesion, corrosion generating of a damage portion, and maintenance management cycle. In this study, a salt water spray test, CASS test, and the electrochemistry examination were carried out for the thermal metal spray method of construction for corrosive protection performance evaluation. Moreover, the corrosive protection life of a thermal metal spray method of construction was quantitatively calculated on the basis of this experiment. in consideration of LCC, the economical efficiency of a general corrosive protection method of construction and a thermal metal corrosive protection method of construction was compared. Consequently, although initial construction expense was estimated 16 to $30\%$ high, as for a thermal metal spray method of construction, it turns out that the administrative and maintenance expenses for 100 years became cheap 9.3 to 13 or more times.