• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.109-113
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• 2004

We have manufactured and characterized the fiber-to-Planar Waveguide Coupler for analysis of the photo-induced refractive index change of DM-BTE .(l,2-bis[2,5-dimethylthio-phen-3-yl]-hexafluorocyclopentene) When irradiated with ultraviolet light, the colorless diarylethene(DM-BTE)-crystal turned red while keeping the crystal shape. The red color was bleached by irradiation with visible light(λ＞450 nm). The resonant wavelength was shifted and recovered owing to the refractive index variation of the planar waveguide because of its photo-functional properties on exposure to UV and visible light. The wavelength responses of this switch by UV exposure were measured as 0.057 nm/sec with saturation time of 60 seconds. and when illuminated by visible light, resonance wavelength variations were measured as 0.028 nm/sec, with recovery time of 140 seconds.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.731-736
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• 2012

A new method for producing boron-containing nanoparticles is described. Boron trichloride ($BCl_3$) and methane ($CH_4$) are dissociated through injection into a thermal plasma followed by a nucleation process producing boron or boron carbide nanoparticles. X-ray photoelectron spectroscopy was used to detect B-C bonds related to the carbide state and to probe the ratio of boron to carbon in the B-C bond structure. In addition, nanoparticles were characterized with scanning transmission electron microscopy and electron energy loss spectroscopy. It was found that nanoparticles were in the range 30-70 nm and a boron to carbon ratio in the B-C bond structure of up to 2 can be reached when $BCl_3$ of 20 sccm and $CH_4$ of 25 sccm were used.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.675-682
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• 2013

In this study, to enhance the quality of concrete surface by removing the surplus water, permeable liner attached the euroform was applied for manufacturing concrete specimens. Various kinds of concrete mixtures with different water to binder ratios were applied and the strength properties of the hardened concrete surfaces were evaluated at different heights. Experimental results showed that the rebound values by schmidt hammer test and the compressive strengths on the surfaces of concrete specimens were increased as proportion to the amount of mixture water which is dependent on the water to binder ratio of each concrete mixture, and more enhancements were observed on the middle and lower specimen surfaces than the upper region. SEM analysis also showed that much denser hydrate structures were observed on the specimen surfaces by the application of the permeable liner while similar hydrate formations were occurred regardless of surface treatment conditions. From the MIP test results of the concrete surfaces, it was observed that, by the application of permeable liner, the pore volume below $0.01{\mu}m$ was decreased with a maximum of 50% resulting in the densification of pore structures.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.4
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• pp.87-94
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• 1999

This paper presents a study on the off-line handwritten Hangul (Korean) character recognition using the partially connected neural network (PCNN), which is based on partial connections between the input receptive fields and the hidden nodes. The hidden nodes of three PCNNs have ten receptive fields and different input feature sets. And we introduce modular partially connected neural network (MPCNN), The MPCNN combines three PCNNs with a merging network. The learning scheme of the proposed networks is composed of two steps: PCNN learning step and the merging step of combining three PCNN s. In the merging step, another merging PCNN network is introduced and trained by regarding the hidden output of each PCNN as a new input feature vector. The performance of the proposed classifier is verified on the recognition of 18 off-line handwritten Hangul characters widely used in business cards in Korea.

• Korean Journal of Crystallography
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• v.2 no.1
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• pp.12-16
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• 1991

C18H22N4OS, Mr=342.47, monoclinic, P2₁/c,a=11.802(2), b=31.962(2), c=9.829(2)A, β=100.12(1)˚, V=3694.8A3,F(000)=1472, Z=8, Dx=1.246 Mg m-3, Dm=1.17Mg m-3,λ=0.71073 A, μ=0.15mm-1, T=294 K. final R=0.0856 for 3718 observed reflection (Fo>3σ(Fo)) There are two molecules in an asymmetric unit and a major difference between these molecules is in the C(9)-N(1)-C(6)-C(7) torsion angles [58.8(8)˚and 1(1)˚]. Both molecules have intramolecular N(1)-H(10)'N(3) hydrogen bonds [ 2.613(7) and 2.566(7) A] and assume V-shaped conformation with N(2) atoms at the verices. The two independent molecules are linked by the two N(2)-H(11)'S' hydrogen bonds[3.367(5) A and 3.421(4)A] and the dimergen are held together by van der Waals forces.

• Journal of the Korean Chemical Society
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• v.40 no.3
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• pp.187-195
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• 1996

Ab initio SCF calculations have been carried out for the five conceivable trimers formed between one hydrogen cyanide and two hydrogen fluorides using a basis set of TZ＋P quality. Several ground state properties of these trimeric complexes have been evaluated, and compared with those of isolated monomers and appropriate dimers. Computed equilibrium geometries, stabilization energies, and dipole moments are given in order to suppliment the available experimental data. At this level of approximation, intramolecular bond distances are consistently shorter than experimental ones. However, intermolecular distances upon complex formation, and dipole moments are overestimated compared with experimental ones. HCN$(HF)_2$ trimer appears to be the most favourable among the five kinds of trimer complex, and also more stable than $(HCN)_2HF$. The typical features of the non-additivity of intermolecular interaction are relatively strong in the HCN$(HF)_2$ trimer.

• Polymer(Korea)
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• v.37 no.1
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• pp.94-99
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• 2013

Polydiacetylene (PDA) is made by photopolymerization of self-assembled diacetylene monomers. If diacetylene monomers are arranged systematically and close enough with distance of atoms, 1,4-addition polymerization will occur by the irradiation of 254 nm ultraviolet rays and then PDA will have alternated ene-yne polymer chains at the main structure. Aqueous solutions of diffused PDA is tinged with blue which shows ${\lambda}_{max}$ 640 nm. Visible color changes from blue to red occurs in response to a variety of environmental perturbations, such as temperature, pH, and ligand-receptor interactions. In this study, we synthesized cationic peptides - PCDA(10,12-pentacosadyinoic acid) liposome using a solid phase peptide synthesis (SPPS) method and prepared liposome solutions at various molar ratios using MPEG-PCDA. When mammalian cells were treated with the liposomes, high transfection efficiency and low toxicity were observed.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.210-216
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• 2012

For the recycling of rapid-cooled steel slag, various specimens were prepared with the various replacement ratios of the rapid-cooled steel slag and the addition ratios of polymer binders. The physical properties of these specimens were then investigated by absorption test, compressive strength test, flexural strength test and hot water resistance test, and the pore and the micro-structure analysis was performed using scanning electron microscope. Results showed that the flexural strength increased with the increase of rapid-cooled steel slag and polymer binder, but the compressive strength showed a maximum strength at a certain proportion. By the hot water resistance test, compressive strength and flexural strength decreased remarkably and the total pore volume increased but the pore diameter decreased. SEM observation of the structure before the hot water resistance test revealed a very compact infusion of structure but the decomposition or thermal degradation appeared in polymer binders when observed after the hot water resistance test.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.127-134
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• 2019

The aim of this study was to evaluate the compomer cement and resin cement as an orthodontic band cement on zirconia crown. A total of 30 specimens were prepared. Preformed stainless steel crowns and zirconia crowns of upper right second primary molar were used. Orthodontic bands were cemented on stainless steel crowns (Group I, n = 10) and zirconia crowns (Group II, n = 10) with compomer cement. The other bands were cemented on zirconia crowns with resin cement (Group III, n = 10). The tensile loads were applied to band to measure the bond strength. The mean of bond strengths of group I, II and III were 0.79 MPa, 1.09 MPa and 1.56 MPa respectively. Bond strength of group II is significantly higher than group I. There was no significant difference between group II and III. Compomer cement and resin cement containing functional monomers showed favorable bond strength of orthodontic bands.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.106-113
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• 2002

In spacecraft system, structure subsystem has the mission of supporting all the components safely under various space environmental conditions. The safety of spacecraft structure is finally verified from the coupled load analysis, which is a branch of load analysis which combines the launch vehicle and satellite. This study introduces the optimization algorithm to reduce the weight of spacecraft structure under launch environmental conditions directly. The acceleration responses are obtained by the introduction of coupled load analysis, which lead to check the failure of spacecraft structural members. The results show a 12% saving of structural weight and this saving is mainly driven by the thickness of honeycomb core, which strongly affects the natural frequencies of platforms and panels.