• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.203-209
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• 2017

The propenyl ether-type monomers which are applicable for cationic photo-polymerization were synthesized by the condensation reaction of mono and di-functional alcohol with allyl bromide. To examine photo-curable reactivity, these monomers were combined with cationic photoinitiator to prepare coating composition. As a result, the initial rate of polymerization of POMB in mono propenyl ether type was 10.2, which was relatively lower than BPOB in di-propenyl ethers type. However, POMB containing 1.5mol% photoinitiator almost quantitatively reacted within 90 seconds. In addition, Sulfonium salt type photo-initiators containing long-alkyl group showed good solubility with monomers and apperaed to have comparatively higher rate of polymerization and conversion ratio when applying DPSA and DPST which have high acidity on all monomers.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.277-284
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• 2011

In this study, UV-curing type organic - inorganic hybrid hard coating solutions were prepared from alumina sols and acrylate monomers. The mixture of alumina sols, prepared from aluminum isopropoxide, and a silane coupling agent, methacryloxypropyl trimethoxysilane(MPTMS), was used as an inorganic component. Also, the mixture of acrylate monomers, pentaerythritol triacrylate(PETA), 1,6-hexanediol diacrylate(HDDA) and dipentaerythritol hexaacrylate (DPEHA), was used as an organic component. The organic-inorganic hybrid coating solutions were obtained by mixing the inorganic component and organic component, deposited on polycarbonate substrates by spin coating and densified by UV-curing. The effect of the amount of MPTMS in the inorganic component and the irradiation time during UV-curing was studied on the properties of coating films. As a result, when 0.20 mole of MPTMS was used, the pencil hardness of coated films showed an excellent pencil hardness of 3H and also exhibited a good abrasion resistance of 2% in haze.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.111-118
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• 2002

A new lithium niobate optical modulator with a polymer buffer layer on Ni in-diffused optical waveguide is proposed for the fist time, successfully fabricated and examined at a wavelength of 1.3 mm. By determining the diffusion parameters of Ni in-diffused waveguide to achieve more desirable mode size which is well matched to the mode in the fiber, the detailed results on the achievement of high optical throughput are reported. In addition, the usefulness of polymer buffer layer which can be applicable to a buffer layer in Ni in-diffused waveguide devices is demonstrated. Several sets of channel waveguides fabricated on Z-cut lithium niobate by Ni in-diffusion were obtained and on which coplanar traveling-wave type electrodes with a polymer-employed buffer layer were developed by a conventional fabrication method for characterizing of electro-optical performances of the proposed device. The experimental results show that the measured half-wave voltage is of ~10 V and the total measured fiber-to-fiber insertion loss is of ~6.4 dB for a 40 mm long at a wavelength of =1.3 mm, respectively. From the experimental results, it is confirmed that the polymer-employed buffer layer in LiNbO3 optical modulator can be a substitute material instead of silicon oxide layer which is usually processed at a high temperature of over $300^{\circ}C$. Moreover, the fabrication tolerances by using polymer materials in LiNbO3 optical modulators are much less strict in comparison to the case of dielectric buffer layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.39-40
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• 2009

The patterned vertical alignment (PVA) display showed good electro-optic properties such as wide viewing angle, fast response time, high Contrast Ratio. However, the device has patterned electrode on both top and bottom electrodes which requires high accuracy of assembling of top and bottom substrates in order to exhibit a high performance. So, they have disadvantage about low yield. In order to resolve these problem, in this paper, we studied about top substrate pattern free vertical alignment device associated with surface polymer stabilization using the UV curable monomer. This method shows simple progress, low cost and good electro-optic properties such as high transmittance and fast response time.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.4
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• pp.476-492
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• 2003

Purpose : The purpose of this study was to compare HEMA and TEGDMA as diluents for the composite resin. Material and methods : Eight kinds of experimental light curable composite resins were prepared and used. Concentrations of monomer and filler were same for all experimental composites, except, the diluent's ratios to the monomer. The ratio of diluents to Bis-GMA were 15%, 20%, 25%, and 30%, and two kinds of diluents were used, so total experimental groups were eight including one control group of 25% TEGDMA. Results : Depth of cure, flexural strength, shear bond strength to bovine enamel, shear bond strength to bovine dentin, water absorption and solubility of composites in water were measured. Sample size for each groups were 10. Arithmetic means were used as each groups representative values, and regression test for two diluents and low concentrations, Duncan's multiple range test, and Two-way ANOVA test were done for kinds of diluents and its concentrations at level of 0.05. Conclusion : Following results were obtained ; 1. There were not significant differences in effects of HEMA and TEGDMA to depth of cure, flexural strength of composites and shear bond strength to bovine enamel (p>0.05). 2. Increase of the concentrations of the diluents made the depth of cure (p<0.001) and flexural strength (p<0.05) a little higher. 3. Shear bond strength to dentin was higher on HEMA containing composites than TEGDMA containing composites (p<0.001). 4. Water absorption was higher on HEMA containing composites than TEGDMA containing composites (p<0.01).

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.224-232
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• 2015

PURPOSE. The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system). MATERIALS AND METHODS. Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (${\alpha}$=.05). RESULTS. There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis. CONCLUSION. In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure.

• Journal of Chest Surgery
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• v.31 no.6
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• pp.629-633
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• 1998

Implantation of malignant cells along the needle aspiration tract is an extremely rare potential complication following a percutaneous fine needle aspiration biopsy of a lung carcinoma. The dissemination of malignant cells by a needle aspiration biopsy may convert an operable and potentially curable lesion into a fatal disease. We report two cases of chest wall implantation of carcinoma of the lung after a thin needle aspiration biopsy. A fifty-five year old male was successfully treated by a radical full-thickness excision of the chest wall and immediate reconstruction with the latissimus dorsi musculocutaneous island flap. A sixty-eight year old female was treated with a partial-thickness excision of the chest wall and skin graft due to superimposed infection and ulceration of the metastatic chest wall carcinoma. One case lived for 31 months up to November 1994, and the other's condtion has been uneventful for 3 months up to now.

• Polymer(Korea)
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• v.34 no.6
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• pp.574-578
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• 2010

In this study, the caprolactone modified hydroxy acrylates (CHAs) were synthesized by ring-opening reaction of caprolactone and 2-hydroxyethyl acrylate (2-HEA) as initiator. Also, the caprolactone modified urethane acrylate (UA) oligomers were synthesized by condensation reaction of previously synthesized CHAs, 2-hydroxyethyl acrylate (2-HEA) and hexamethylene diisocyanate trimer (HDT). Using the hydroxy number of CHAs, the molecular weights of the CHAs were calculated easily and their molecular weight was similar to the theoretical molecular weight of them. The viscosity of UA oligomers decreased as increasing a content of CHA in the UA oligomer. Cure films were prepared from UA oligomer, reactive diluents, and UV initiator to investigate their physical properties. The thermal stability and color difference on high temperature for the cured film were improved as increasing the crosslinking density. Their surface hardness was also increased as increasing crosslinking density of the cured films, but their elongation at break was decreased.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.119-127
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• 2007

Recently, microstructures fabricated using microstereolithography technology have been used in the biological, medical and mechanical fields. Microstereolithography can fabricate real 3D microstructures with fine features, although there is presently a limited number of materials available for use in the process. Deformation of the fine features on a fabricated microstructure remains a critical issue for successful part fabrication, and part deformation can occur during rinsing or during fabrication as a result of fluid flow forces that occur during movement of mechanical parts of the system. Deformation can result in failure to fabricate a particular feature by breaking the feature completely, spatial deflection of the feature, or attaching the feature to neighboring microstructures. To improve mechanical strength of fabricated microstructures, a clay nanocomposite can be used. In particular, a high-aspect ratio microstructure can be fabricated without distortion using photocurable liquid resin containing a clay nanocomposite. In this paper, a clay nanocomposite was blended with a photocurable liquid resin to solve the deformation problem that occurs during fabrication and rinsing. An optimal mixture ratio of a clay nanocomposite was found through tensile testing and the minimal allowable distance between microstructures was found through fabrication experimentation. Finally, using these results, high-aspect ratio microstructures were fabricated using a clay nanocomposite resin without distortion.

• Journal of Yeungnam Medical Science
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• v.3 no.1
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• pp.95-102
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• 1986

Among the skeletal tuberculosis, tuberculous spondylitis is high incidence and curable disease, if early diagnosis and treatment are possible. We reviewed clinical manifestations and radiologic analysis of 30 cases tuberculous spondylitis from May 1983 to Sept. 1986, at Yeungnam medical center, Yeungnam University. The results were follows : 1. The frequent involve sites were thoracolumbar vertebra. 2. The continuous lesion is 86.7% of the all cases. 3. The most common type was intervertebral type, and lytic and sclerotic lesion were same incidence. 4. Paravertebral abscess, kyphosis and disc space narrowing were demonstrated more than 80.0% of the cases. 5. Computed tomography was more accurate diagnostic method rather than conventional plain study to evaluation of extent of lesion, involvement of spinal canal and cord, and size and location of paravertebral abscess. And CT guided abscess drainage procedure was helpful to diagnosis and treatment. 6. Ultrasonography was helpful to differential diagnosis between paravertebral abscess and other solid mass, and useful to follow up study of paravertebral abscess after treatment.