• Journal of Adhesion and Interface
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• v.3 no.1
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• pp.20-23
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• 2002

The wetting properties of an uncured epoxy resin on both clean and oiled, galvanised steel have been studied. Since the polymer is very viscous at ambient temperature, and also with an aim to simulate industrial conditions, the spreading of drops of resin during a heating cycle (temperature increase at $10^{\circ}C/min$) was recorded and analysed. On clean steel, a contact angle, ${\theta}$, vs time, t, plot shows sigmoidal behaviour, whereas on the oiled substrate, spreading almost ceases in an intermediate stage. This strange behaviour is attributed to significant oil absorption by the polymer.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.2 s.110
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• pp.47-56
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• 2005

In technology of ink-jet coating, Image quality from correlation between paper and ink depends on the properties of printer and ink as well as those of paper material. Generally, According to the quality of ink that consists of colorants from 5 to 20 percent, It seems that absorption behavior of each ink is different. In this study, we studied to estimate the effects of dye and pigment ink on the absorption and printing properties using 2-type papers on the market and 3-type silica-based coated papers whose pore structure is different. Using the theory of contact angle to evaluate the absorption property, it was possible to measure the baseline length between paper and ink, volume of droplet as well as contact angle. Also, It was possible to calculate wetting energy(mN/m) and spreading coefficient(mN/m) using the surface tension of each ink. These measurements were available to estimate ink-jet qualities.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.205-209
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• 2009

Wetting properties between silver-copper-titanium braze alloys with different titanium contents up to 2.8 mass% and hexagonal boron nitride ceramics were investigated using sessile drop method at 1123K in Argon. The final contact angle is less than $30^{\circ}$ when the Ti content was over 0.41 mass%. Meanwhile, the contact angle curves show different behavior. In case of using braze alloy containing 2.8 mass% of titanium, the initial contact angle is acute angle just after the melting of braze. In case of brazes containing titanium less than 2.26 mass%, the contact angle is larger than $90^{\circ}$ at the beginning and slowly decreases to acute angle. The reaction layer of titanium nitride is observed at the interface. In addition, the reaction of Ti in the braze and N in the bulk h-BN seemed to show diffusion limited spreading.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.506-512
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• 2013

Recently, the color separation issue of wide-spreading white LEDs has attracted attention due to their wide applicability as light sources in direct-lit LCD backlights. These wide-spreading LED packages usually consist of LED chips, a color-conversion phosphor layer, and a light-shaping lens. The technical aspect of this color issue was related to a method for balancing the yellow spectral component emitting from phosphors with respect to the blue one from the LED chip as a function of viewing angle. In this study, we suggested an approach for carrying out quantitative analysis for the color separation problem occurring in wide-spreading LED packages by optical simulation. In addition, the effect of an internal scattering layer on the color uniformity was investigated, which may be considered as a potential solution for this problem.

• The Journal of Engineering Geology
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• v.16 no.3 s.49
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• pp.275-282
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• 2006

This study was conducted laboratory flume tests to identify landslide features and flow characteristics of debris using a flume test equipment. Under the several test conditions dependent on rainfall intensity and slope angle, the authors measured pore water pressure, slope failure and displacement, spreading area of debris on a regular time interval. The test processes were also recorded by video cameras and digital still cameras. According to the test results, pore water pressures have trends of direct proportion to the rainfall intensity and the slope angle, resulting in high potential of landslide triggering. The spreading area of debris is also increased with the slope angle and the rainfall intensity as well as the rainfall duration.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.3
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• pp.296-304
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• 2011

In order to design a shear coaxial injector of solid particles with water, basic experiments on a particle laden jet are necessary. The purpose of the present study is to understand the effect of particle loading ratio on the particle spray characteristics (i.e. spreading angle, distribution of particle number density, velocity profiles, and particle developing region length). Hydro-reactive Al2O3 particles with a primary particle diameter of 35~50 ${\mu}m$ are used in this experiment. An automated particle feeder was designed to supply constant particle mass flowrates. Air is used as the carrier gas. To determine the air velocity at the orifice exit, tracers (aluminum oxide, 0.5~2 ${\mu}m$ primary diameter) are also supplied by a tracer feeder. A plain orifice type injector with 3 mm diameter, and 20 mm length was adopted. Particle image velocimetry is used to measure the mean and fluctuating velocity components along the axial and radial directions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.348-353
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• 2011

Characteristics of cryogenic single jet flow were investigated. Liquid nitrogen was injected into a high-pressure chamber and formed single jet. Ambient condition around jet was changed from subcritical to superctirical condition of nitrogen. Injector geometries also were changed. A shape of the jet and core diameter were measured by flow visualization technique, and core spreading angle was calculated. Flow instability was found at atmospheric pressure condition. As ambient pressure increased, core spreading angle was increased and maintained after certain pressure.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.280-280
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• 2022

Tiller angle, defined as the angle between the main stem and its side tillers, is one of the main target traits selected inbreeding to achieve the ideal plant type and increase rice yield. Therefore, the discovery and identification of tiller angle-related genes can provide architecture and yield. In the present work, using QTL analysis hence a total of 8 quantitative trait loci (QTLs) were detected based on the phenotype data of tiller angle and tiller crown width in two years. Among them, four QTLs (qTA9, qCW9, qTA9-1, qCW9-1) were overlapped at marker interval RM6235-RM24288 on chromosome 9 with a large effect value regarded as stable major QTL. Twenty tiller angle-related genes were selected from the target region and the relative gene expression levels were checked in five compact type lines, five spreading type lines, and their parental lines. Finally, OsSA URq9 which belongs auxin-responsive SMALL AUXIN UP RNA (SAUR) protein family was selected as a target gene. Overall, this work will help broaden our understanding of the genetic control of tiller angle and tiller crown width, and this study provides both a good theoretical basis and a new genetic resource for the breeding of ideal-type rice.

• Journal of electromagnetic engineering and science
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• v.4 no.4
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• pp.183-189
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• 2004

In this paper, the Eigen-RAKE receiver in wideband direct sequence code-division multiple access(DS-CDMA) systems with downlink smart antenna is analyzed for different spreading bandwidths(1.25 MHz, 5 MHz, 10 MHz) and different channel environments(macro, micro). The realistic spatio-temporal wideband multipath channel is assumed, one of which is standardized multiple-input single-output(MISO) radio channel model for WCDMA link-level simulations proposed by $3^{rd}$ generation partnership project(3GPP) contributions. We assumed spatial scattering phenomenon in which many unresolvable path signals within a limited range of spatial angle simultaneously contribute to the signals received at the receiver. Several multipaths within one chip are distinguished into each one and the first multipath components are selected as the desired signal and the others are considered self-interference. Downlink DS-CDMA system with eigenbeamformer using wider bandwidth present better performance than that using narrow bandwidth system by employing Eigen-RAKE receiver of many number of branches. It is shown that the downlink eigenbeamformer is more effective in typical urban macro cellular environments when using Eigen-RAKE receiver.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.84-87
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• 2009

Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electrowetting, especially in designing electrowetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electrowetting. The result was compared with experimental data. It is shown that contact line friction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models.