• 한국전기화학회:학술대회논문집
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• 2005.07a
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• pp.383-390
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• 2005

Effect of applying a DC voltage on the interfacial reaction at the metal to zirconia interface was investigated utilizing an oxygen ionic conductivity of partially stabilized zirconia. The joining of copper rod and zirconia tube was carried out in Ar gas atmosphere at $1000^{\circ}C$. There are two type of the joining. The one is the reaction bond consisting of copper and zirconia was dominated by surface reaction with a undetectable very thin layer. It was found that copper elements were diffused to zirconia side, but that Zr ions were not diffused to copper side. These results mean application of a DC voltage to migrate oxygen to the copper-zirconia interface can oxidize metal at the copper-zirconia interface and the bonding reaction between zirconia and copper oxide may occur. The other is the reaction bonding was dominated by interdiffusion with a very thick interface layer. This result mean application of a DC voltage can reduce zirconia at the interface. The bonding reaction is to be an alloying between Zr and Cu.

• Journal of Drive and Control
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• v.12 no.4
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• pp.35-40
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• 2015

A gas spring provides support force for lifting, positioning, lowering, and counterbalancing weights. It offers a wide range of reaction force with a flat force characteristic, simple mounting, compact size, speed controlled damping, and cushioned end motion. The most common usage is as a support on a horizontally hinged automotive tail gate. However, its versatility and ease of use has been applied in many other industrial applications ranging from office equipment to off-road vehicles. The cylinder of a gas spring is filled with compressed nitrogen gas, which is applied with equal pressure on both sides of the piston. The surface area of the rod side of the piston is smaller than the opposite side, producing a pushing force. The magnitude of the reaction force is determined by the cross-sectional area of the piston rod and the internal pressure inside the cylinder. The reaction force is influenced by many design parameters such as initial chamber volume, diameter ratio, etc. In this paper, we investigated the reaction force characteristics and carried out parameter sensitivity analysis for the design parameters of a gas spring.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.3
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• pp.205-215
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• 2002

The purpose of this study was to evaluate the tissue response in various bone grafting materials, especially xenogenous bone materials in vivo, compare of bone formation capacity of various bone grafting materials on rat skull defects and evaluate the effect of Hyaluronic acid on healing of human Demineralized Freezed Dried Bone allogenous graft (DFDBA) materials in rat calvarial defects. 30 Sprague-Dawly rats were divided into 4 groups. $7{\times}7mm$ size bony defect were artificially prepared in the calvaria (both parietal bone) of all 30 rats and follwed group grafting of autogenous bone graft on right side and allogenic DFDBA on left side bone graft (rat DFDB) in 15 control group, but in 15 experimental group, xenograft (human DFDB) on left side, hyaluronic acid treated with xenograft on right side. Sequential sacrifices was performed at 1, 2, 4, 6, 8 weeks of experiment. These specimens were stained with H&E and MT stain, and then histologic analysis under light microscope was carried out. There were inflammatory reaction in all graft material during early stage. Autogenous and Allogenous DFDBA graft group observed inflammatory reaction at 1 week. Xenograft group persistant inflammatory reaction until 4 weeks, but in HA treated xenograft group inflammatory reaction was decreased at 2 weeks. Osteoblastic activity in control group was begun at 2 week, xenograft group was delayed at 6 weeks, however HA treated xenograft group was begun at 4 weeks. At 2 week, mild osteoclastic activity were observed in all xenograft group not in concerned to HA, but there was no difference each group after 4 weeks. There are most activated angiogenesis around graft mateirals in xenograft group at 2 weeks, but in HA treated xenograft group, decreased angiogenesis was observed at same time. Bone formation and bone maturation of xenograft group, there was no difference in HA treatment, was less than control group. Fibrosis around xenograft materials were observed until 6 weeks, there was no difference between xenograft and HA treated groups.

• Macromolecular Research
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• v.17 no.2
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• pp.84-90
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• 2009

We prepared side-chain liquid crystalline polymers comprising two monomeric units, one having a mesogenic side group that could form a smectic mesophase and the other having a phenolic group attached to the polymer backbone via a thermally reversible urethane bond. The urethane linkage between the isocyanate and phenol groups was stable at room temperature, but it cleaved to generate an isocyanate group when the temperature was increased. When annealed, the copolymers in their smectic mesophases became insoluble in common organic solvents, suggesting the formation of network structures. XRD analysis showed that the annealed polymers maintained their smectic LC structures. The crosslinking process probably proceeded via the reaction of the dissociated isocyanate groups. Some of the isocyanate groups would have first reacted with moisture in the atmosphere to yield amino groups, which underwent further reaction with other isocyanate groups, resulting in the formation of urea bonds. We presume that only polymer chains in the same layer were crosslinked by the reaction of the isocyanate groups, resulting in the formation of a layered polymer network structure. Reactions between the layers did not occur because of the wide layer spacing.

• The korean journal of orthodontics
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• v.9 no.1
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• pp.99-103
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• 1979

For the purpose of investigating the response of the periodontal tissue in relation to the experimental tooth movement, the rats were inhibited from collagen formation by adminstration of aminoacetonitrile. Findings were as follows: 1) In experimental group, the principal fibers of the periodontal ligament came to run parallel along the alveolar bone or root surface on the pressure side, while the decrease in density, irregular arrangement, and partial loss of principal fibers were observed on the tension side. 2) Sharpey's fibers at the alveolar bone decreased in number, and as the aminoacetonitrile administration continued, the capability of matrix formation decreased on the tension side, the narrowing of the alveolar septum and poor-bony trabeculation appeared on the pressure side. 3) In cementum, Sharpey's fibers were distributed irregularly. The formation of acellura cementum was decreased on the tension side, while the formative capability of cellular cementum was increased. 4) The degree of staining by Herovici technique decreased in the periodontal membrane. By PAS and ninhydrine -Schiff reaction it was appeared weakly positive in the region where the Sharpey's fibers existed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.77-80
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• 2006

Graft copolymerized polycarboxylate(PC)-type superplasticizers(PCs) which have carboxylic acid with $\pi$ bond among the molecular structure and polyethyleneglycol methyl ether methacrylate(PMEM) were synthesized by free radical reaction and investigated the chemical structure, polymerization condition, and physical and chemical properties. Also, the effects of PCs in the dispersion, adsorption and hydration of cement were evaluated. As the molecular weight of graft chain decreases, the adsorption amount on cement particles increased. It was advantageous for the flow to reduce molar ratio, the lower the side bone molecular weight, and increase the molar ratio, the larger the side bone molecular weight. The hydration reaction speed was highly delayed at day 1, due to increase in molar ratio and reduction in side bone molecular weight, but it was recovered in the days after.

• Journal of the Korean Society of Combustion
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• v.5 no.1
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• pp.7-18
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• 2000

Numerical simulations of counterflow non-premixed $CH_4/C_2HCl_3/Air$ flames added 8%(by volume) C2HCl3 on the fuel side are conducted at atmospheric pressure using a detailed chemical reaction mechanism in order to understand the effect of strain rates. A detailed sensitivity analysis is also performed in order to assess the relative influence of each reaction on the flame established at a strain rate of 200s-1. The structure of flames (i.e., temperature, velocity, and concentration of species) established at both a strain rate of 150s-1 and 300s-1 are investigated. As the strain rate increases, the "flame zone" is restricted to a narrower range and the position of maximum temperature is shifted to the fuel side. The concentrations of major species, H2O, CO, H2, HCl, Cl2, and Cl are decreased with increased strain rate. The reaction involving chlorine, CH4 + Cl $\rightarrow$ CH3 + HCl, instead of the reaction, CH4 + H $\rightarrow$ CH3 + H2 influences the consumption of methane. C2HCl3 + OH $\rightarrow$ CHCl2 + CHOCl and HCl + OH $\rightarrow$ H2O + Cl, are major reactions, through which OH radicals are consumed.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.179-186
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• 2000

Interactions between wheel lug surfaces and soil were analyzed through wheel motion. In this paper, lug surfaces such as trailing and leading lug sides and a lug face were analyzed and reported. The interactions between the surfaces and soil were expressed as the horizontal and vertical directions of resultant forces acting on the surfaces. There analysis indicated qualitatively that (1) the trailing lug side is mainly related to produce motion resistance and reaction to dynamic load, (2) the lug face is related to produce not only the motion resistance, the reaction to the dynamic load but also the traction and (3) the leading lug side is mainly related to produce the traction and the reaction to the dynamic load. Experiments were conducted to prove the results of the motion analysis. Normal and tangential forces acting on the surfaces were measured, and the traction, the motion resistance and the reaction to the dynamic load were calculated with wheel rotational and lug design angles. The experiments proved that the results of wheel motion analyses above mentioned as (1), (2) and obtained from the analysis were correct.

• Journal of Korea Foundry Society
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• v.22 no.2
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• pp.89-96
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• 2002

This study examined the effects of adding Zn to Sn-3.5Ag solder on the microstructure changes and behavior of interface reaction of the solder joint with Cu substrate. The solder/Cu joints were examined with microscope to observe the characteristics of microstructure changes and interfacial reaction layer with aging treatment for up to 120 days at $150^{\circ}C$. Results of the microstructure changes showed that the microstructures were coarsened with aging treatment, while adding 1%Zn suppresses coarsening microstructures. The Sn-3.5Ag/Cu had a fast growth rate of the reaction layer in comparison with the Sn-3.5Ag-1Zn at the aging temperature of $150^{\circ}C$. Through the SEM/EDS analysis of solder joint, it was proved that intermetallic layer was $Cu_6Sn_5$ phase and aged specimens showed that intermetallic layer grew in proportion to $t^{1/2}$, and the precipitate of $Ag_3Sn$ occur to both inner layer and interface of layer and solder. In case of Zn-containing composite solder, $Cu_6Sn_5$ phase formed at the side of substrate and Cu-Zn-Sn phase formed at the other side in double layer. It seems that Cu-Zn-Sn phase formed at solder side did a roll of banrier to suppress the growth of the $Cu_6Sn_5$ layer during the aging treatment.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.5
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• pp.753-757
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• 2010

The objectives of this paper is to propose the pharmacoepidemiologic methodology to Research for Sasang Constitutional Pharmacology. We mainly searched "Journal of Pharmacoepidemiology and Risk Management". And we also searched "J Korean Oriental Med.", "J of Sasang Constitutional Med.", "J. Oriental Physiology & Pathology", "Korean J Orient Int Med." using these kew words - "adverse event" or "side effect" and "Sasang Contitution" or "Constitution" or "Constitutional medicine". Through the examination of the Pharmacoepidemiologic methodology and current research for sasang constitiutional pharmacology, we could establish the proposal to collect objective constitutional medical reaction. For the actualization of this proposal, the more advanced studies will have to be carried out continuously.