• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.275-276
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• 2009

We have studied physical properties of organic light-emitting diodes (OLEDs) in a device with 7,7,8,8-tetracyanoquinodimethane (TCNQ). Since the TCNQ has a high electron affinity, it is widely used for a charge-transport and injection layer. And the TCNQ-derivatives have also been used to control the conductivity of the materials. It is known that a charge injection and transport in OLEDs with a TCNQ-derivative enhances a performance of the devices such as operating voltage and efficiency. To see how the TCNQ affects on the device performance, we have made a reference device in a structure of ITO(170nm)/TPD(40nm)/$Alq_3$(60nm)/LiF(0.5nm)/Al(100nm). And several type of devices were manufactured by doping TCNQ either in TPD or $Alq_3$ layer. The TCNQ layer was also formed in between the organic layers. N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD), tri(8-hydroxy quinoline) aluminium ($Alq_3$), and TCNQ layers were formed by thermal evaporation at a pressure of $10^{-6}$ torr. The deposition rate was $1.0{\sim}1.5\;{\AA}/s$ for TPD, and $1.0{\sim}1.5\;{\AA}$ for $Alq_3$. The LiF was thermally evaporated at a deposition rate of $0.2\;{\AA}/s$ successively. The device with TCNQ-derivative improved the turn-on voltage compared to the one without TCNQ-derivative.

• Korean Journal Plant Pathology
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• v.1 no.1
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• pp.33-37
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• 1985

A yellow stripe and bud benting disease of soybean was commonly observed on the field at Suweon area. The causal agent was identified as alfalfa mosaic virus (AMV) by indicator plant reactions, physical properties, serological test and electron microscopy. AMV produced vein clearing, top necrosis, top bent and mottling on the parts of soybean plants. Local lesions were produced on the inoculated leaves of Vigna sesquipedialis, Vicia faba and Tetragonia expansa, while Chenopodium am, anticolor, C. quinoa, Pisum satvium, Petunia hybrida and Nicotiana tabacum 'Bright yellow' were systemically infected. The thermal inactivation point was $60^{\circ}C$, dilution end point was $10^{-3}$, and longevity in vitro was 2 days at room temperature. AMV from soybean was reacted with AMV - antiserum in agar gel diffusion test. Electron microscopy of AMV from soybean exhibited bacilliform particles of 60nm in length.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.53-62
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• 1999

Micro polysilicon actuators, which are widely used in the field of MEMS (Microelectromechanical System) technology, were fabricated using polysilicon thin layers. Polysilicon deposition were carried out to have symmetrical layer structures with a LPCVD (Low Pressure Chemical Vapor Deposition) system, and we have measured physical characteristics by micro test patterns, such as bridges and cantilevers to verify minimal mechanical stress and stress gradient in the polysilicon layers according to the methods of mutilayer deposition, doping, and thermal treatment, also, analyzed the properties of each specimen, which have a different process condition, by XRD, and SIMS etc.. Finally, the fabricated planar polysilicon resonator, symmetrically stacked to $6.5{\mu}m$ thickness, showed Q of 1270 and oscillation ampitude of $5{\mu}m$ under DC 15V, AC 0.05V, and 1000 mtorr pressure. The developed micro polysilicon resonator can be utilized to micro gyroscope and accelerometer sensor.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.432-436
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• 2017

Carbon blocks were prepared by compression molding process using the mixture of isotropic cokes and binder pitches, which were reformed with different ${\beta}$-resin contents from pyrolysis fuel oil. Physical and chemical properties and also thermal behavior of binder pitches were investigated through elemental analysis, FT-IR and thermogravimetric analysis, respectively. The adhesion of binder pitches to isotropic coke particles was evaluated from SEM images of the fracture surface of carbon blocks. From these results, it is shown that the adhesion between the cokes and binder was enhanced by increasing the ${\beta}$-resin content of binder pitches. The density of the carbon block after carbonization also increased from 1.325 to $1.383g/cm^3$ by increasing the ${\beta}$-resin content of binder pitches from 1.4 to 20.1%.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.51-62
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• 2006

Three strains of Cucumber mosaic virus (CMV) have been found to cause a lethal disease, referred to as fern leaf syndromes and mild mosaic symptoms in tomato (Lycopersicon esculentum Mill.) crops grown in Kuwait. CMV strains were detected and identified based on host range, symptomatology, serology, electron microscopy, and ribonucleic acid (RNA) electrophoresis in polyacrylamide gels. A high degree of viral genomic heterogeneity was detected among CMV strains isolated in Kuwait, with no apparent correlation to symptomatology in tomato host plants. Two different virus satellites of 'CMV associated RNA 5', designated CARNA 5, were detected in two virus strains that caused both lethal disease and mild symptoms, designated CMV-D1 and CMV-S1 respectively. CARNA5 was not detected in the third CMV strain that caused fern leaf syndromes designated CMV-F. All the three isolated strains were serologically indistinguishable from each other and may belong to one serotype according to Ouchterlony gel diffusion tests. These strains transmitted via aphids (Myzus persicae Sulz) in a non-persistent manner. Physical properties of the virus strains were very similar where thermal inactivation test showed that virus withstood heating for 10 min at $70^{/circ}$, dilution end point was $10^{-4}$, and the longevity in vitro at room temperature was less than 5 days for all virus strains. CMV-D1 and CMV-F were the most devastating diseases spreading in both greenhouse and field-grown tomato where aborted flower buds failed on fruit setting due to the viral infection. This is the first report to isolate three different strains of CMV in Kuwait.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.49-55
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• 2013

To explore the paper materials for restoration of the Annals of the Joseon Dyansty, durability of the three type of the traditional Korean Papers were estimated in this study, through moist heat artificial aging test. Three types(D, F, and G) which showed the best preservation performance in dry heat and UV treatment in the previous study were selected and artificial accelerated aging treatment with moist-heat process was conducted; the viscosity change rate was D>G>F; folding endurance G>D>F; $L^*$ value F>D>G; $a^*$ and $b^*$ change rate D>G>F; brightness decrease rate D>G>F, suggesting paper F showed the least change rate in physical/optical properties. Also the CLSM image observation showed fair coherence among fibers and confirmed paper mulberry. And in FDI extraction from each sample, paper F showed the highest value. Overall, paper F (traditional glossy paper) showed the highest stability against thermal treatment. It confirms that paper F is suitable as restoration paper for tributary remains including the annals of the Joseon Dynasty for its steady strength/viscosity decrease rate and color change rate.

• Polymer(Korea)
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• v.29 no.3
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• pp.253-259
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• 2005

Polyurethanes, synthesized by polyester polyols and aliphatic or aromatic diisocyanates for a crease resist finishing agent, were prepared by two-step reactions, that is, prepolymer synthesis and chain extension. The structures of synthesized polyurethanes were confirmed by the measurement of FT-IR and $^1H$-NMR spectrometer. The number average molecular weight ($\bar{M}_n$) and the weight average molecular weight ($\bar{M}_w$) of the polyurethane with aromatic diisocyanate (MDI) were higher than those of the synthesized polyurethanes with aliphatic diisocyanate (HDI, $H_{12}MDI$). The glass transition temperatures ($T_g$) of soft segments in polyurethanes with MDI, HDI, $H_{12}MDI$ were -25,-42 and -50$^{circ}C$, respectively. In the polyurethanes obtained by two-step reaction, thermal stability and tensile strength increased with increasing hard segment contents, whereas elongation at break decreased with increasing hard segment contents.

• Korean Journal of Optics and Photonics
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• v.21 no.5
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• pp.214-223
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• 2010

Optimization of a 30 cm lightweight mirror was proposed with the best optical performance under various loads of gravity and thermal loads with proper boundary conditions. A pattern for a lightweight mirror was generated based on the best optical performance combined with ease of manufacturing for proper design parameters of physical properties of face sheet, back sheet, rib, and web. Evaluation of the optical performances of a telescope mirror was obtained by using the finite element analysis program, NX I-DEAS. Surface errors, individual aberration terms, such as piston, tilts, focus and other aberrations were calculated by using Zernike polynomials. The proposed telescope mirror meets well the opto-mechanical design consideration of RMS surface error less than 16 nm.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.139-152
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• 2006

Many experimental and numerical approaches have been developed to evaluate paving materials and to predict pavement response and distress. Micromechanical simulation modeling is a technology that can reduce the number of physical tests required in material formulation and design and that can provide more details, e.g., the internal stress and strain state, and energy evolution and dissipation in simulated specimens with realistic microstructural features. A clustered distinct element modeling (DEM) approach was implemented In the two-dimensional particle flow software package (PFC-2D) to study the complex behavior observed in asphalt mixture fracturing. The relationship between continuous and discontinuous material properties was defined based on the potential energy approach. The theoretical relationship was validated with the uniform axial compression and cantilever beam model using two-dimensional plane strain and plane stress models. A bilinear cohesive displacement-softening model was implemented as an intrinsic interface and applied for both homogeneous and heterogeneous fracture modeling in order to simulate behavior in the fracture process zone and to simulate crack propagation. A disk-shaped compact tension test (DC(T)) with heterogeneous microstructure was simulated and compared with the experimental fracture test results to study Mode I fracture. The realistic arbitrary crack propagation including crack deflection, microcracking, crack face sliding, crack branching, and crack tip blunting could be represented in the fracture models. This micromechanical modeling approach represents the early developmental stages towards a 'virtual asphalt laboratory,' where simulations of laboratory tests and eventually field response and distress predictions can be made to enhance our understanding of pavement distress mechanisms, such its thermal fracture, reflective cracking, and fatigue crack growth.

• Journal of the Korean Vacuum Society
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• v.12 no.1
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• pp.25-34
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• 2003

Deposition behavior of hard amorphous carbon film was investigated by molecular dynamic simulation using Tersoff potential which was suggested for the interaction potential between carbon atoms. When high energy carbon atoms were collided on diamond (100) surface, dense amorphous carbon film could be obtained. Physical properties of the simulated carbon film were compared with those of the film deposited by filtered cathodic arc process. As in the experimental result, the most diamond-like film was obtained at an optimum kinetic energy of the incident carbon atoms. The optimum kinetic energy was 50 eV, which is comparable to the experimental observation. The simulated film was amorphous with short range order of diamond lattice. At the optimum kinetic energy condition, we found that significant amount of carbon atom were placed at a metastable site of distance 2.1 $\AA$. By melting and quenching simulation of diamond lattice, it was shown that this metastatic peak is Proportional to the quenching rate. These results show that the hard and dense diamond-like film could be obtained when the localized thermal spike due to the collision of high energy carbon atom can be effectively dissipated to the lattice.