• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.63-71
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• 2009

In order to improve flame retardancy, the halogen free organic melamine phosphate(M-P) flame retardant was synthesized from melamine and phosphoric acid by the reaction of precipitation. The ignition test was carried out preparing hybrid flame retardant compound($H_bFRC$) consisting of organic M-P and inorganic Mg$(OH)_2$ as a flame retardant in the polyolefin resins. The flame retardancy and mechanical properties of flame retardant aluminum composite panel($H_bFRC$-ACP) were performed to investigate the possibility of the composite material, which was contained M-P, as a inner core for $H_bFRC$-ACP. For this study, the results of ignition test indicate that a char formation and drip suppressing effect, and combustion time reduced as the content of M-P increased. The limited oxygen index(LOI) values were measured 17.4vol% and 31.5vol% for LDPE only and $H_bFRC$-3(M-P content: 15wt%), respectively. And it was verified that the $H_bFRC$-3 was needed more oxygen quantity with the increase of M-P content when it combustion. Also, the results from thermogravimetric analysis were observed endothermic peak at $350^{\circ}C$ and $550^{\circ}C$, it was confirmed predominant thermal stability though the wide temperature range by the mixture of M-P and Mg$(OH)_2$. The LDPE-ACP (using only LDPE as a inner core), $35.13kW/m^2$ of heat release rate(HRR) and 13.43MJ/m2 of total heat release(THR) were measured while the $H_bFRC$-ACP, $10.44kW/m^2$ of HRR and 1.84MJ/m2 of THR were measured by results of cone calorimeter test. In case of $H_bFRC$-ACP, the average gas emission amount of CO and $CO_2$ could be decreased down to 25% and 20%, respectively, in comparison with LDPE-ACP. The mechanical properties such as tensile strength, bending strength and adhesion strength of $H_bFRC$-ACP were revealed slightly high values $54N/mm^2$, $152N/mm^2$ and 120N/25mm, respectively, compared with LDPE-ACP. It was confirmed that flame retardancy was improved with the synergy effect because of char formation by M-P and hydrolysis by Mg$(OH)_2$. The result of this study suggest that $H_bFRC$ can be applied for an adequate halogen free flame retardant composite material as a inner core for ACP.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.99-106
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• 1999

Ultra-high molecular weight polyethylene (UHMWPE) was crosslinked in the melt state to enhance wear resistance, Dicumyl peroxide (DCP) and triallyl cyanurate (TAC) was used as a crosslinking agent and a promoter, respectively. With increasing amount of DCP and TAC used, gel content of crosslinked UHMWPE (XUMPE) increased, while the melting temperature, crystallizaiton temperature, crystallinity, and tensile properties decreased. The results of pin-on-disk wear test and ball-on-disk test with small applied load showed reduced wear volumes of XUMPE from that of the unmodified UHMWPE. As the wear mechanism effected in the experimental condition of this study was thought to be deformation rather than adhesion or fatigue, a new parameter, the ratio of maximum contact stress to yield stress, was proposed to correlate well with observed wear resistance. In ball-on-disk wear test with larger applied load, XUMPE showed higher wear volumes than that of the unmodified UHMWPE which were accompanied with increased friction coefficients and surface roughness of the wear tracks. When contact stress was well above yield stress, the failure of XUMPE, as well as deformation, was thought to be much accelerated.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.197-206
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• 2000

The deposition characteristics of MOCVD Cu using the (hfac)Cu(1,1-COD)(1,1,1,5,5,5-hexafluoro-2,4-pentadionato Cu(I) 1,5-cyclooctadine) have been investigated in terms of the effects of carrier gas such as hydrogen and argon as well as the effects of H(hfac) ligand addition. MOCVD Cu using a hydrogen carrier gas led to a higher deposition rate and lower resistivity than an argon carrier gas system. The improvement in the surface roughness of the MOCVD Cu films and the (111) preferred orientation texture was obtained by using a hydrogen carrier gas. However, the adhesion characteristics of the films showed relatively weaker compared to the Ar carrier gas system, probably due to the larger amount of F content in the films, which was confirmed by the AES analyses. When an additional H(hfac) ligand was added, the deposition rate was significantly enhanced in the case of an argon + H(hfac) carrier gas system while significant change in the deposition rate of MOCVD Cu was not observed in the case of the hydrogen carrier gas system. However, the addition of H(hfac) in both carrier gases led to lowering the resistivity of the MOCVD Cu films. In conclusion, this paper suggests the deposition mechanism of MOCVD Cu and is expected to contribute to the enhancement of smooth Cu films with a low resistivity by manipulating the deposition conditions such as the carrier gas and addition of H(hfac) ligand.

• Journal of The Korean Ophthalmological Society
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• v.58 no.5
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• pp.509-515
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• 2017

Purpose: To compare the amoebicidal effects of nephrite containing contact lens (CL) storage cases with conventional CL storage cases. Methods: Acanthamoeba lugdunensis were inoculated onto 5% nephrite containing CL storage cases as well as conventional CL storage cases both with and without silicone hydrogel contact lenses (SHCLs). Then the amount of Acanthamoeba proliferation on CL storage cases and the number of adherent Acanthamoeba on SHCLs were determined and compared. The effects of multipurpose solution (MPS) with and without 1% or 5% nephrite solution on Acanthamoeba adhesion were analyzed. Results: Nephrite containing CL storage cases showed more inhibitory effects on Acanthamoeba proliferation (p = 0.02) and significantly reduced the number of adherent Acanthamoeba on SHCLs compared with conventional CL storage cases, regardless of SHCLs generation (p = 0.001, p = 0.001 and p < 0.001, respectively). The number of adherent Acanthamoeba on the first generation of SHCLs was significantly reduced by MPS with 1% and 5% nephrite solutions (p = 0.03 and p = 0.004, respectively), but the numbers for the second and third generation SHCLs were not. Conclusions: Nephrite could be used as a new additive component for CL storage cases and multipurpose solutions to improve the disinfection effects on Acanthamoeba.

• Journal of Life Science
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• v.28 no.11
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• pp.1379-1385
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• 2018

Glycans are attached to proteins as in glycoproteins and proteoglycans. They are found on the exterior surface of cells. O- and N-linked glycans are very common in eukaryotic cells but may also be found in prokaryotes. The interaction of cell surface glycans with complementary glycan binding proteins located on neighboring cells, other cell types, pathogens like virus, or bacteria is crucial in biologically and biomedically important processes like pathogen recognition, cell migration, cell-cell adhesion, development, and infection. Their implication in pathological condition, suggests an important role for glycans as disease markers. In addition, a great amount of research has been shown that appropriate glycosylation of a recombinant therapeutic protein is critical for product solubility, stability, pharmacokinetics and pharmacodynamics, bioactivity, and safety. Besides, cancer-associated glycosylation changes often involve sialic acid in glycan branch which play important roles in cell-cell interaction, recognition and immunological response. This review aims at giving a comprehensive overview of the glycan's biological function and describing the relevance among the glycosylation, disease diagnosis and treatment methods. Furthermore, the high-throughput analytic methods available to measure the profile changing patterns of glycan in the blood serum as well as possible underlying biochemical mechanisms.

• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.289-297
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• 2019

Epoxy resin adhesives are currently used as adhesives in buildings. Epoxy resin adhesives, which are organic materials, generate harmful substances when producing adhesives, and toxic substances are high in the residential space after installation. In addition, a large amount of carbon monoxide generated from organic materials in the case of a building fire leads to personal injury. This study evaluates the feasibility of inorganic adhesives using pure inorganic materials such as magnesia, phosphate, and borax as inorganic adhesives to replace existing organic adhesives. As a result of the experiment on the selection of adequate phosphate and the characteristics of the addition rate of borax used as a retarder, the potassium phosphate monobasic was obtained as a suitable phosphate and the characteristics according to the borax addition rate were compared with the quality standard of KS F 4923 The hardening shrinkage and heat change rate satisfied the quality standards. The tensile strength was satisfactory when the borax addition rate was 4% or more, but the adhesive strength did not meet the quality standards. Further studies are needed to improve adhesion strength.

• Journal of Chest Surgery
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• v.38 no.9 s.254
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• pp.627-632
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• 2005

Background: The video-assisted thoracic surgery (VATS) with 2 mm thoracoscopy in primary spontaneous pneumothorax (PSP) was known to be unreliable in its accuracy and recurrence rate. We compared 10 mm VATS with 2 mm VATS in the results of operation. Material and Method: From Sept. 1998 to Dec. 2002, 176 cases (10 mm VATS; 73 cases, 2 mm VATS; 103 cases) of PSP were treated by VATS blob resection at Korea University Ansan Hospital. 10 mm thoracoscope, 5 mm port, and 5 mm instruments were used in 10 mm VATS group, and 2 mm thoracoscope, 2 mm ports and 2 mm instruments used in 2 mn VATS group. In the two groups, staples were inserted through 11.5 mm port for chest tube. Result: The mean follow-up duration was 20,8$\pm$16.1 months in 10 mm VATS group, and 13.9 $\pm$8.2 months in 2 mm VATS. The most common indication of operation was a recurrent pneumothorax ($34\%$) in 10 mm VATS and patient's desire ($40\%$) in 2 mm VATS, respectively. The operation time, number of staples used in operation, postoperative chest tube keeping days, postoperative total amount of drainage, and postoperative hospitalization days were statistically lower in 2 mm VATS. Other significant variables affecting the operation time in linear regression analysis were the number of staples that used in operation, the presence of pleural adhesion, and type of pleurodesis and thoracoscope used in operation. However, $R^2$ values were lower than 0.1. The postoperative recurrence rate was $2.7\%$ in 10 mm VATS and $2.9\%$ in 2 mm VATS. It was not significant statistically. Recurrent cases developed within 1 year in both groups but the difference was statistically insignificant. Conclusion: Although there were differences in follow-up duration between two groups, the operation time, number of staples that used in operation, postoperative chest tube keeping days, postoperative total amount of drainage, and postoperative hospitalization days were statistically lower in 2 mm VATS. And in 2 mm VATS, there were no technical difficulties during operation and no differences in recurrence rate from 10 mm VATS. As a result, we suggest that 2 mm VATS can be used in the treatment of PSP.

• Journal of Chest Surgery
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• v.30 no.10
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• pp.991-1000
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• 1997

Closed thoracostomy with UWSD* which is the most utilized procedure in chest surgery applies general thoracic disorders, trauma and after-thoracic surgery. The University hospital was involved on operating 2341 cases of closed thoracostomy with UWSD except chest tubing after-thoracic surgery for a full six years from January, 1991 to December, 1996. The rate of men and women out of the total 2341 cases was 3.5 : 1, the distribution by age showed that men were 36.6 $\pm21.0$ years old, women were $47.0\pm20.2$ years old and so that the total were 40.0 $\pm$ 20.5 years old. As for indication, spontaneous, secondary and traumatic pneumothorax were the most common, in addition to hemothorax hemopneumothorax, hydrothorax, hydropneumothorax, empyema, chylothorax. The most indwelling period of chest tubing is between eight and fourteen days for 974 cases and the average is 13.7 $\pm$ 6.3 days, The average drainage amount immediately after thoracostomy was 537 $\pm$ 88m1, and in 694 cases(46.0%), the drain amount was 201 ~ 500 ml. The rate of right and left tubing was 52.4 47.6, in 2071 cases(88.5%), the thoracostomy was the first chance and 2210 cases(94.4%) were treated with a single tube drainage. Almost all the patients complained of tube site pain, besides tube site infection, intercostal neuralgia, loss of tube function by the pleural adhesion, intrathoracic infection, incomplete reexpansion of defective lung, hemorrhage caused by the rupture of a blood vessel, subcutaneous emphysema, lung parenchymal rupture, diaphragmatic and intraabdominal trauma, reexpansionary pulmonary edema of one side lung and cellulitis were relapsed. 84.6% of all patients recovered with only clo ed thoracostomy and the rest of patient needed additional some necessary managements and so on to have successful results. There were two deaths(0.1%), caused by reexpansionary pulmonary edema, the cellulitis were complicated by thoracostomy with UWSD on an empyema patients to come to death(due to sepsis). t UWSD = under water seal drainage

• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.429-455
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• 2002

There are numerous kind of materials and techniques to regenerate the periodontal tissue which has been lost due to destructive periodontal disease, including bone graft material. Many bone graft materials have been reported and among these materials, synthetic material has been developed fin the long time because of its sufficient supply economically. Calcium sulfate which was evaluated as including much calcium, has been used in the clinical field. In the dental field calcium sulfate has been used as bone graft material and Kim reported that improved bone formation and more amount of new attachment after grafting calcium sulfate. but, because calcium sulfate has the problem that it generates the heat in setting period and resolves fast, we need to evaluate the effect of the improved calcium sulfate on periodontal tissue. The present study evaluates the effect of paste type calcium sulfate on the epithelial migration, alveolar bone regeneration, cementum formation and gingival connective tissue attachment in intrabony defect in dogs. Four millimeter deep and four millimeter wide 3-wall defects were surgically created in the mesial or distal aspects of premolars or molars. the test group received paste-type calcium sulfate with a flap procedure and the control group underwent flap procedure only. Histologic analysis after 8 weeks of healing revealed the following results : 1. The length of epithelial growth(the distance from CEJ to the apical end of JE) was 0.52${\pm}$0.26mm in the control and 0.56${\pm}$0.25mm in the test group. there was no statistically significant difference between the two groups. 2. The length of connective tissue adhesion was 1.74${\pm}$1.06mm in the control and 1.28${\pm}$0.57mm in the test group. there was no statistically significant difference between the two groups. 3. The length of new bone was 2.01${\pm}$0.95mm in the control and 2.62${\pm}$0.81mm in the test group. there was no statistically significant difference between the two groups. 4. The length of new cementum was 1.86${\pm}$0.80mm in the control and 2.77${\pm}$ 0.86mm in the test group. there was a statistically significant difference between the two groups.(P<0.01) These results suggest that the use of paste type calcium sulfate in 3-wall intrabony defects has significant effect on new cementum formation , but doesn't have any significant effect on the prevention of junctional epithelium migration and new bone formation. Finally, the paste type calcium sulfate that is used in this study is suggested to be the material that can have a significant effect on the periodontal healing, if its biocompatibility is improved.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.559-571
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• 2017

This study was conducted to determine the adhesive performances of plywoods affected by layering direction and the amounts of thermoplastic films. The face and back layers of veneer were hardwood species (Mixed light hardwood) and core layer veneer was radiata pine (Pinus radiata D. Don). Thermoplastic film used as adhesive were polypropylene (PP) film and polyethylene (PE) film. Thermal analysis and tensile strength were investigated on each films. As a result, the melting temperature of PP and PE films were $163.4^{\circ}C$ and $109.7^{\circ}C$, respectively, and the crystallization temperature were $98.9^{\circ}C$ and $93.6^{\circ}C$, respectively. Tensile strength and elongation of each films appeared higher on the width direction than length direction. Considering the characteristics of the thermoplastic films, the test for the amount of film used was carried out by layering film to the target thickness on veneer. The effecting of layering direction of film on plywood manufacturing was conducted by laminating in the length and width directions of the film according to the grain direction of veneer. Tensile-shear strength of plywood in wet condition was satisfied with the quality standard (0.7 MPa) of KS F 3101 when the film was used over 0.05 mm of PP film and over 0.10 mm of PE film. Tensile-shear strength of plywood after cyclic boiling exceeded the KS standard when PP film was used 0.20 mm thickness. Furthermore, higher bonding strength was observed on a plywood made with width direction of film according to grain direction of veneer than that of length direction of film. Based on microscopic analysis of the surface and bonding line of plywood, interlocking between veneers by penetration of a thermoplastic film into inner and cracks were observed.