• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.8
• /
• pp.1145-1151
• /
• 1989

New method to calculate the characteristics of the dominant and higher order modes of waveguide latching phase shifters are presented. Due to the tensor permeability, E and H fields inside the ferrite are expanded in terms of the LSE and LSM eigenmodes of the dielectric-slab-loaded waveguide. The equivalent coupled transmission line equations on the transverse plane are derived to obtain the dispersion characteristics and the E and H field distributions. Numerical results at X-band are compared with those published previously. The derived field distributions can be used to suppress the higher order modes of the latching phase shifters, so that the phase shift from the dominant mode only contributes the performance of the phase shifters.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.758-762
• /
• 2007

Revenue management is a new approach method to solve the problem of supply and demand, and one of fields which is diffused quickly at the service enterprise to use perishable-asset like the transportation business. It is based on multiple fare policy that discount charge reservation should be received if the benefit value of current discount fare is more than expected profit of the normal fare reservation it will be able to occur in future when suitable goods is sold to the customers at discount fare, at the time they want, and at assigned seat by controlling supply and demand from market. In this research, I will review on initial operation case for special class goods that the seat which is limited is assigned at some of train and portion of KTX for demand dispersion and new demand creation at peak time, put a limit in purchase conditions, and provides discounted fare. I will also try to find implication for strategic operation.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.611-617
• /
• 2003

This study was performed to develop the method for producing industrial coal sources by cleaning Korean anthracite. Laboratory hindered-settling separation column was set and three coal samples were used for tests. Tests were conducted to evaluate the effects of the major operating variables, teeter water flow rate and relative column pressure (set point). Additional tests were performed to elevate the yield and properties of the products using air bubble injecting process. In results, nice products were obtained with high teeter water flow rate and air bubble injection. Also, model of continuous hindered-settling separation process was established to assist the evaluation of the equipment and several operating variables, such as dispersion, teeter water flow rate, feeding rate, etc.

• Proceedings of the Optical Society of Korea Conference
• /
• 2000.02a
• /
• pp.82-83
• /
• 2000

초고속 광통신 시스템 구현에 있어서 핵심기술의 하나인 광섬유의 색분산 제어와 함께 그 정확한 측정을 위한 여러 방법들이 연구되어 왔으나, 기존의 방법들은 실험 장치가 복잡하고 광대역의 광원을 필요하므로 저가의 시스템 구현 및 실제적 응용이 어렵다.$^{(1)}$ 실제 시스템에 장착되어 있는 필드에서 응용 될 수 있기 위해서는 소형이며 온도와 같은 외부 환경에 민감하지 않은 시스템을 필요로 한다. 본 연구에서는 실제필드에서의 광섬유에 대한 정확한 색분산 측정을 위한 시스템 개발을 목적으로 이득스위칭된 다모드레이저 및 고분산광섬유(Highly Dispersive Fiber)를 이용한 색분산 측정시스템을 제안한다. (중략)

• Korean Journal of Optics and Photonics
• /
• v.5 no.2
• /
• pp.252-259
• /
• 1994

The method of calculating overlap dispersion caused by group velocity mismatch between uv and visible pulses in ultrafast pump-probe experiments is presented to discuss limitations of the time resolution and signal intensity. The calculations show arrangements using a single focusing lens shall result in undesirable time resolution and low signal intensity. Achromatic doublets result in unrealistic solutions. However, dramatic improvement in the time resolution and signal intensity is expected in the optical arrangements using separate lens for each pulse and in the arrangements using a cutoff secondary lens with a main lens. lens.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.969-974
• /
• 2004

Although guided-waves are very efficient for long-range nondestructive damage inspection, it is not easy to extract meaningful pulses of small magnitude out of noisy signals. The ultimate goal of this research is to develop an efficient signal processing technique for the current guided-wave technology. The specific contribution of this investigation towards achieving this goal, a two-stage Gabor pulse-based matching pursuit algorithm is proposed : rough approximations with a set for predetermined parameters characterizing the Gabor pulse and fine adjustments of the parameters by optimization. The parameters estimated from the measured signal are then used to assess not only the location but also the size of a crack existing in a rod. To validate the effectiveness of the proposed method, the longitudinal wave-based damage detection in rods is considered. To estimate the crack size, Love's theory for the dispersion of longitudinal waves is employed.

• International journal of advanced smart convergence
• /
• v.7 no.2
• /
• pp.86-94
• /
• 2018

This study focuses on presenting the IT program module provided by real - time forecasting and database of the voluntary disclosure quality measure in order to solve the problem of capital cost due to information asymmetry of external investors and corporate executives. This study suggests a model of the algorithm that the quality of real - time voluntary disclosure can be provided to all investors immediately by IT program in order to deliver the meaningful value in the domestic capital market. This is a method of generating and analyzing real-time or non-real-time prediction models by transferring the predicted estimates delivered to the Big Data Log Analysis System through the statistical DB to the statistical forecasting engine.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.4
• /
• pp.424-431
• /
• 1999

The reproducibility of successive growth of $Bi_{12}TiO_{20}$ (BTO) single crystlas using a top-seeded solution growth (TSSG) pulling method was evalutated by measuring the lattice constants and their standard deviations. A substantial phase diagram in the region close to the stoichiometric BTO was established expermentally for this purpose, and the existence of a retrograde solid solution close to a BTO was clarified. It was emphasized that a starting solution, with a 10.0~10.1 mol% $TiO_{2}$ concentration, results in large single crystals with a highly homogeneous lattice constant of within ${\pm}1{\times}10^{-4}\AA$, when the solidified fraction of the grown crystal is less than about 45 %. A wavelength dispersion of refractive index was measrued for the first time, and it was verified that the refractive index of BTO is larger than that of BSO($Bi_{12}TiO_{20}$), allowing the voltage sensitivity of EOS higher than the case with BSO as a probe head.

• Journal of the Korean Ceramic Society
• /
• v.48 no.2
• /
• pp.147-151
• /
• 2011

In this study, we prepared graphene by using the modified Hummers-Offeman method and then introduced the metals (Pt, Pd and Fe) for dispersion on the surface of the graphene for synthesis of metal-graphene composites. The characterization of the prepared graphene and metal-graphene composites was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and transmission electron microscopy (TEM). According to the results, it can be observed that the prepared graphene consists of thin stacked flakes of shapes having a well-defined multilayered structure at the edge. And the metal particles are dispersed uniformly on the surface of the graphene with an average particle size of 20 nm.

• Journal of Environmental Science International
• /
• v.12 no.1
• /
• pp.41-45
• /
• 2003

Magnetite powder for kerosene-based ferrofluid was synthesized by air oxidation of waste acid containing $Fe^{2+}$ and $Fe^{3+}$ ions in the pH=11 at $60^{\circ}C$. Stable kerosen-based ferrofluid was prepared by addition of polyoxyethylene nonylphenyl ether(POENPE) to the magnetite containing water. Dispersion mechanism of an addition POENPE to the magnetite was examined by means of the fraction of solid dispersed FT-IR spectrum. And magnetic properties of kerosen-based ferrofluid were examined by method of Vibrating Sample Magnetometer. In order to remove oil on the water surface by an addition of kerosen-based ferrofluid, the optimum conditions were examined.