• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.229-229
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• 2010

With the scaling down of ultra large integrated circuits (ULSI) to the sub-50 nm technology node, the need for an ultra-thin, continuous and conformal diffusion barrier and Cu seed layer is increasing. However, diffusion barrier and Cu seed layer formation with a physical vapor deposition (PVD) method has become difficult as the technology node is reduced to 30 nm and beyond. Recent work on self-forming barrier processes using PVD Cu alloys have attracted great attention due to the capability of conformal ultra-thin barrier formation using a simple technique. However, as in the case of the conventional barrier and Cu seed layer, PVD of the Cu alloy seed layer will eventually encounter the difficulty in conformal deposition in narrow line trenches and via holes. Atomic layer deposition (ALD) has been known for its good step coverage and precise thickness control, and is a candidate technique for the formation of a thin conformal barrier layer and Cu seed layer. Conformal Cu-Mn seed layers were deposited by plasma enhanced atomic layer deposition (PEALD) at low temperature ($120^{\circ}C$), and the Mn content in the Cu-Mn alloys were controlled form 0 to approximately 10 atomic percent with various Mn precursor feeding times. Resistivity of the Cu-Mn alloy films decreased by annealing due to out-diffusion of Mn atoms. Out-diffused Mn atoms were segregated to the surface of the film and interface between a Cu-Mn alloy and $SiO_2$, resulting in self-formed $MnO_x$ and $MnSi_xO_y$, respectively. No inter-diffusion was observed between Cu and $SiO_2$ after annealing at $500^{\circ}C$ for 12 h, indicating an excellent diffusion barrier property of the $MnSi_xO_y$. The adhesion between Cu and $SiO_2$ was enhanced by the formation of $MnSi_xO_y$. Continuous and conductive Cu-Mn seed layers were deposited with PEALD into 32 nm $SiO_2$ trench, enabling a low temperature process, and the trench was perfectly filled using electrochemical plating (ECD) under conventional conditions. Thus, it is the resultant self-forming barrier process with PEALD Cu-Mn alloy film as a seed layer for plating Cu that has further potential to meet the requirement of the smaller than 30 nm node.

• Journal of Veterinary Clinics
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• v.24 no.3
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• pp.315-319
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• 2007

Transgastric endoscopic cholecystectomy was successfully accomplished in a 1-year-old, 15 kg, female, mongrel dog. Single-working channel flexible gastric endoscope was used with the aid of one abdominal laparoscopic port. Gastrotomy was performed using endoscopic needle knife at the ventral antral region. Through the gastric incision endoscope was advanced and retroflexed for the visualization of gallbladder. For the better exposure of surgical field, gentle traction was applied at the fundus of the gallbladder using laparoscopic grasping forceps. Cystic duct and artery was ligated using endoclips. After transecting the duct and artery, gallbladder was dissected using endoscopic coagulating grasping forceps and needle knife. Resected gallbladder was retrieved through the mouth and gastric incision site was sutured using endoclips. There was no evidence of bile leakage or stomach leakage on postoperative day (POD) 3. On POD 16, gastric endoscopy and laparoscopy was performed. Gastric endoscopy revealed complete adhesion of incision site. The content of the peritoneum appeared healthy, with no sign of infection, bile staining, or organ injury. The omentum was adhered over resected gallbladder fossa and the serosal surface of gastrotomy site. This is the first report of NOTES cholecystectomy in the dog and provides new concept of cholecystectomy of the dog.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.288-294
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• 1999

In the flip chip interconnection using solder bump, the Under Bump Metallurgy (UBM) is required to perform multiple functions in its conversion of an aluminum bond pad to a solderable surface. In this study, various UBM systems such as $Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 5\mu\textrm{m}, Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}, al 1\mu\textrm{m}/Ni 0.2\mu\textrm{m} / Cu 1\mu\textrm{m} and Al 1\mu\textrm{m}/Pd 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}$ for flip chip interconnection using the low melting point eutectic 63Sn-37Pb solder were investigated and compared to their metallurgical properties. $100\mu\textrm{m}$ size bumps were prepared for using an electroplating process. The effects of the number of reflows and aging time on the growth of intermetallic compounds(IMC) were investigated. $Cu_6Sn_5$ and $Cu_3Sn$ IMC were abserved after aging treatment in the UBM system with thick coper $(Al 1\mu\textrm{m}/Ti 0.2\mu\textrm{m}/Cu 5\mu\textrm{m})$. However only the $Cu_6Sn_5$ was detected in the UBM system with $1\mu\textrm{m}$ thick copper even after 2 reflow and 7 day aging at $150^{\circ}C$. Complete Cu consumption by Cu-Sn IMC growth gives rise to a direct contact between solder inner layer such as Ti, Ni and Pd, and hence to possibly cause reactions between two of them. In this study, however, only for the Pd case, IMC of PdSn. was observed by Cu consumption. UBM interfacial reactions with s이der affected the adhesion strength ot s이der balls after s이der reflow and annealing treatment.

• Journal of Physiology & Pathology in Korean Medicine
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• v.29 no.1
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• pp.27-32
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• 2015

Streptococcus mutans triggers dental caries establishment by two major factors. One is synthesis of organic acids which demineralize dental enamel and the other is synthesis of glucans which mediate the attachment of bacteria to the tooth surface. In the present study, we evaluated the effect of the ethanol extracts of Aconitum koreanum (A. koreanum ) on the growth and acid production of S. mutans. Ethanol extracts of the A. koreanum showed concentration dependent inhibitory activity against the growth and acid production of S. mutans, and produced significant inhibition at the concentration of 0.016 mg/ml compared to the control groups (p<0.05). The extracts inhibited S. mutans adherence to hydroxyapatite treated with saliva, and cell adherence was repressed by 50%, 54% at the concentration of 0.063, 0.125 mg/ml. On the study of activation of glucosyltransferase which synthesizes water insoluble glucan form sucrose, the ethanol extract of A. koreanum showed remarkable inhibition over the concentration of 0.016, 0.031, 0.063 and 0.125 mg/ml (p<0.05). Especially on the concentration of 0.063, 0.125 mg/ml, the extracts suppressed the glucan synthesis by 100%. We analyzed the component of the extracts of A. koreanum. The results showed that the extract of A. koreanum had strong phenolic compound, glycosides and organic acids. These results suggest that A. koreanum may inhibit the caries-inducing properties of S. mutans, and which may be related with strong phenolic compound, glycosides and organic acids.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.99-107
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• 2003

Normally coating is used a method for protecting reinforced concrete. For this purpose, organic as well as inorganic coatings are used. The advantages of inorganic coatings are lower absorption of UV, non-burning etc. On the other hand, organic coatings have the advantage of low permeability of $CO_2$, $SO_2$ and water. Organic coatings provide better protection for reinforced concrete. However, in organic coatings such as epoxy, urethane and acryl, long-term adhesive strength is reduced and the formed membrane of those is blistered by various causes. Also when organic coatings are applied to the wet surface of concrete, they have a problem with adhesion. So, we developed coating material, WGS-Eco which was hybridized with polymer and cement based material to protect concrete structures and solve problems of organic coatings. This study was conducted an comparative evaluation on physical and durable performance of developed coating material and previously used coating materials. As a result, the performance of developed coating material was not inferior to organic coating materials. So, the developed coating material was considered as a suitable coating material which had advantages of inorganic and organic coatings for protecting concrete.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.597-605
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• 2019

In order to improve the adhesion of water-based adhesive, gemini type nonionic reactive surfactants were synthesized and applied to water-based adhesives. The surfactants were synthesized by using maleic acid and polyoxyethylene cetyl ether having different length of ethylene oxide and confirmed by FT-IR and $^1H-NMR$. Their appearance was light yellow wax. The cloud point of the compound was more than $78^{\circ}C$. The measured critical micelle concentration (c.m.c) was $1.0{\times}10^{-4}{\sim}7.0{\times}10^{-4}mol/L$ and surface tension at c.m.c was 25.9~32.0 mN/m. As the number of ethylene oxide increased, the emulsifying power was improved. The foaming height of each compound by Ross-Miles method was 1.4~4.5 cm. The synthesized surfactants was then used as an emulsifier in emulsion polymerization of water-based adhesives and its physical properties were evaluated. The solid contents of prepared adhesives was 59%. The average particle size and initial tackiness of the prepared adhesives were 164~297 nm and ball no. of 20~32, respectively. The peel strength was $1.8{\sim}2.1kg_f/mm$. The retention rate of adhesives viscosity was evaluated to 99% during 30 days. Therefore, synthesized gemini type nonionic reactive surfactants are expected to be applied as an emulsifier for the high adhesive force.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.1-7
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• 2017

As a part of studies to lower the infrared (IR) emissivity from the surface of exhaust nozzle in the turbo jet engine, stainless steel plate was coated with copper particle/meta-aramid resin composites and the IR emissivity of the plate were investigated. Binders of filler particles based on synthetic polymers generally undergo thermal decomposition before $300^{\circ}C$. It was found that the meta aramid resin was thermally stable after the test at $320^{\circ}C$, confirming the excellent thermal stability. Contents of copper particles in the composites were varied from 0 to 70% by volume. It was observed that the copper particle/meta aramid resin composites showed good adhesion after the tests at $320^{\circ}C$. The specimen coated with the composite containing 50 vol% of copper particles showed the lowest IR emissivity, 0.6, at $320^{\circ}C$.

• Composites Research
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• v.33 no.6
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• pp.360-364
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• 2020

Although research and development of existing steel-made Cowl Cross Member(CCM) was carried out with magnesium and plastic to make vehicles lighter, it is difficult to apply them to performance problems in the vehicle's mounting condition. Recently, the company is conducting research on the injection CCM of the composite insert as a lightweight component that is most suitable for mass-production of automotive parts. This is a manufacturing process that inserts composite injection bracket parts into aluminum bar, and the adhesion of the two parts is one of the important factors considering the vehicle's mounting conditions. In this study, the joint strength of Aluminum bar is one of the important factors as a study for the injection of aluminum bar into PA6-GF60 composite material. For the analysis of these research, the method of spraying adhesive to the aluminum bar and the case of knurling treatment have been analyzed and the bonding strength of the direction of rotation and lateral direction has been analyzed for each part between the aluminum bar of the cowl cross member and the shape of the injection component of composite materials.