• Journal of the Korean Institute of Telematics and Electronics
• /
• v.5 no.1
• /
• pp.1-5
• /
• 1968

GaAs single crystals were grown epitaxially from Ga solution with carrier concentrations in the range and electron mobilities between 7,500 and 9,300$\textrm{cm}^2$/v-sec. at 300$^{\circ}$K, and 50,000 and 95,000 $\textrm{cm}^2$/V-sec. at 77$^{\circ}$K. A comparison of the theoretical and experimental curves for the mobility vs. temperature indicates that the significant scattering mechanisms are ionized impurities and phonons in the temperature range of 77$^{\circ}$K to 439$^{\circ}$K. This indicates that the epitaxial layers do not contain other mobility limiting imperfections to a significant degree. Photoluminescence spectra of the. epitaxial layers did not show any emission due to deep lying imperfection leve1s.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.2
• /
• pp.71-79
• /
• 2015

This paper describes vegetation based soil-media hydroseeding measures that have been previously applied as slope revegetation methods show problems such as insufficient binding force, drying, and insufficient organic matter. In particular, in the case of slope faces in regions where scattering is severe, a vicious circle exists in which remarkably low vegetation cover rates and increases in withering rates over time lead to further decreases in vegetation cover rates, which lead to further increases in erosion and scattering. Therefore, in the present study, environment friendly soil stabilizers were applied for resistance against erosion or scattering and engineering evaluations such as long-term immersion tests and flow resistance tests were conducted to determine appropriate mixing ratios. According to the results of long-term immersion tests utilizing environment friendly soil stabilizers and existing greening soil based materials, 100% collapse occurred at 30 hours and 40 days in the case of soil stabilizer mixing ratios of 0% and 2%, respectively. While the original form of the samples remained intact until the experiment was completed in the case of mixing ratios exceeding 4% indicating that 2% or higher soil stabilizer mixing ratios could affect the maintenance of forms even under extreme conditions. In addition, artificial rainfall tests were conducted on 40, 45, and 55 degree slope faces to evaluate the structural stability of vegetation based materials. Flow resistance tests were conducted on soil stabilizer mixing ratios of 0, 4, 8% to evaluate erosion resistance capability. Based on the results of the tests, environment friendly soil stabilizers applied for prevention of scattering or resistance against erosion by rainwater are considered to provide large effects to reduce losses and loss rates showed a tendency of decreasing rapidly when soil stabilizers were mixed.

• Journal of Radiation Protection and Research
• /
• v.36 no.2
• /
• pp.59-63
• /
• 2011

It is important to reduce indirect scattered neutron beside direct neutron of chosen energy for designing a neutron-reference-field laboratory with neutron produced from a nuclear reaction by a accelerator. Therefore MCNPX simulation was performed with various conditions for obtaining such condition. At first in the original laboratory condition we calculated the direct neutron flux which was inserted in chamber (virtual chamber composed of air) of 0 degree (proton moving direction) for neutron flux measurement and the scattered neutron flux which is inserted in the chamber after scattering wall or bottom. In the result, the scattered neutron which was inserted after scattering bottom is more than that which was inserted after scattering the others. Therefore MCNPX simulation was again performed with removing the concrete bottom and with removing the concrete bottom and digging 1 m in the ground. In the result of removing concrete bottom and digging 1 m in the ground, scattered neutron which was inserted after scattering bottom became less than that which was inserted after scattering the others.

• Current Optics and Photonics
• /
• v.4 no.3
• /
• pp.174-185
• /
• 2020

Multiscattering occurs when a laser transmits into dense atmosphere targets (e.g. fogs, smoke or clouds), which can cause depolarization effects even though the scattering particles are spherical. In addition, multiscattering effects have additional information about microphysical properties of scatterers. Thus, multiscattering can be utilized to study the microphysical properties of the liquid water cloud. In this paper, a Monte Carlo method was used to simulate multi-scattering transmission properties of Lidar signals in the cloud. The results showed the slope of the degree of linear polarization (SLDLP) can be used to invert the extinction coefficient, and then the cloud effective size (CES) and the liquid water content (LWC) may be easily obtained by using the extinction coefficient and saturation of the degree of linear polarization (SADLP). Based on calculation results, a microphysical properties inversion method for a liquid cloud was presented. An innovative multiscattering polarization Lidar (MSPL) system was constructed to measure the LWC and CES of the liquid cloud, and a new method based on the polarization splitting ratio of the Polarization Beam Splitter (PBS) was developed to calibrate the polarization channels of MSPL. By analyzing the typical observation data of MSPL observation in the northern suburbs of Nanjing, China, the LWC and CES of the liquid water cloud were obtained. Comparisons between the results from the MSPL, MODIS and the Microwave radar data showed that, the microphysical properties of liquid cloud could be retrieved by combining our MSPL and the inversion method.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.9
• /
• pp.883-890
• /
• 2011

A numerical study was conducted to determine the optimal design for a vehicle vacuum pump. The degree of vacuum was examined for different design factors such as the angle of vanes, number of vanes, angle and position of the pump inlet-outlet pipe, and angular rotational speed of vanes. The results show that there is a little difference in the degree of vacuum when the angle of vanes are changed, but an angular change in the outlet pipe reduces the pump loss. As the rotational speed is increased, the mass flow rate increases, but a high rotational speed does not result in the maximum degree of vacuum. In addition, when the number of vanes is increased, the scattering range of mass flow rate decreases and pressure drop is abated.

• Applied Chemistry for Engineering
• /
• v.22 no.2
• /
• pp.190-195
• /
• 2011

To investigate the photon-trapping effect and scattering layer effect of $TiO_2$ multi-layer in dye-sensitized solar cell (DSSC) and the degree of recombination of electrons at the electrode treated $TiCl_4$, we formed electrodes of different conditions and obtained the most optimal electrode conditions. To estimate characteristics of the cell, IV curve, UV-Vis spectrophotometer, electrochemical impedance spectroscopy (EIS) and incident photon-to-current conversion efficiency (IPCE) were measured. As a result, we confirmed that the multi-layer's efficiency was higher than that of monolayer in the IV curve and the performance of $TiCl_4$ treated electrode was increased according to decreasing the impedance of EIS. Among several conditions, the efficiency of the cell with scattering layer is higher than that of a layer with the base electrode about 19%. Because the light scattering layer enhances the efficiency of the transmission wavelength and has long electron transfer path. Therefore, the value of the short circuit current increases approximately 10% and IPCE in the maximum peak also increases about 12%.

• Journal of Broadcast Engineering
• /
• v.22 no.3
• /
• pp.375-380
• /
• 2017

This paper has proposed a single image based fog degree quantification method by measuring both transmission and local contrast. The proposed method estimates the foggy expected regions from transmission, and then assesses the size of regions of which transmission values are foggy expected ones and the range of local contrast value on such regions. Compared with fog degree gauged by the scattering coefficient measurement sensor, the proposed method quantifies the fog degree with more than 95% accuracy for images containing various objects and environments. We also developed a technique that measures the local contrast values in process of measuring transmission values. So, the proposed method does not increase complexity compared to the existing transmission method.

• Journal of the Korean Ceramic Society
• /
• v.32 no.3
• /
• pp.305-312
• /
• 1995

Thin films of Pb(Mg, Zn)1/3Nb2/3O3 were fabricated by spin coating the Pb-Mg-Zn-Nb-O complex alkoxide sols on(111) Pt-coated MgO (100) planes. It was observed that the content of H2O and the rheological characteristics of sol greatly influenced the orientation of perovskite grains after thin-film formation. A strong preferential orientation of (100)-type planes of the perovskite grains was obtained for the sol aged for 15 days with the molar ratio of H2O to total metal alkoxides=2. As small angle X-ray scattering experiment in the Porod region was performed to correlate the observed preferential orientation with the network structure of precursors at various stage of aging. It was shown that the degree of branching of the Pb-Mg-Zn-Nb-O precursor chain had a direct effect on the preferred oreintation, and weakly branched precursor systems led to highly oriented grains after thin-film formation.

• Journal of Korean Medical classics
• /
• v.32 no.3
• /
• pp.73-83
• /
• 2019

Objectives : The purpose of this paper is to investigate the mechanism of 'Joy impairs the Heart'. Methods : "Huangdineijing" was searched in relation to 'Joy' and 'Heart', then Joy was divided into physiological and pathological joy. After examination of the similarities and differences between the two, the mechanism of 'Joy impairs the Heart' was drawn out. Results : 1. Excessive Joy not only relaxes Qi(氣), but also disperses Shen(神). 2. Impairment of Heart damages heart locally and Impairment of Yang not only damages Qi or Shen focally, but also damages Yang of the whole body and the degree of damage is thought to be more extensive than "Joy impairs the Heart". 3. "Too much joy and pleasure can cause the Shen(神) to scatter and not remain stored." not only relaxes Qi, but also disperses Shen(神), and the degree of damage is less than "Sudden joy damages Yang". Conclusions : Excessive or Sudden Joy impairs the Heart by disturbing Heart's property of maintaining Taiyang by scattering Shen(神) or not maintaining high Yang density. Forced expression of Joy impairs the Heart by relaxing and stagnating Qi.

• Polymer(Korea)
• /
• v.36 no.2
• /
• pp.149-154
• /
• 2012

The amphiphilic copolymer by the conjugation of biocompatible chitosan and antioxidant lipoic acid was studied as a drug delivery carrier. The amphiphilic copolymer was self-assembled to form nanoparticles in the aqueous solution. 5-Fluorouracil widely used as an anticancer drug was encapsulated inside the nanoparticles by a solid dispersion method. The degree of branching of lipoic acid on chitosan was controlled to obtain the optimal condition for the drug delivery carrier. The sizes of nanoparticles were about 250 nm by the dynamic light scattering. The encapsulation efficiency of nanoparticles were about 10%. The copolymer with 42% degree of branching showed the best performance as a drug delivery carrier.