• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.176-185
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• 2009

The realization and the performance of ICP source are strongly affected by its electrical impedance and the electric/magnetic field distribution. The ICP source impedance is determined by the antenna impedance and the plasma one. It is preferred to keep the imaginary impedance between -100 ohm to 100 ohm, since it should be avoided the high voltage formation on the antenna and abrupt impedance variation during the thin film process. The plasma uniformity is affected by the electric and magnetic field which is formed by the antenna current and voltage. The influence of azimuthal symmetry are shown by the electromagnetic simulation and the measurement result of plasma density. The radial uniformity can be controlled by locating the concentric antennas which have different diameters. The power distribution ratio and its control method are presented in the case of parallel antenna connections.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5801-5812
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• 2014

The retention basin is a hydraulic structure for flood mitigation by storing river flow over a design flood. In this study, numerical models were adopted to simulate the flood mitigation effects by a retention basin. The large flood condition was applied as a boundary condition to consider an abnormal flood caused by climate change. Furthermore, the two-dimensional numerical model was adopted to regenerate the complex flow pattern due to the topography and lateral flow near the retention basin. The numerical results of the one- and two-dimensional model were analyzed and compared. The results showed that the two-dimensional model is more applicable to assessing flood mitigation by the retention basin with a complex topography and lateral flow patterns.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.95-100
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• 2007

In this paper, a twice folded TEM horn antenna for 70 kV impulse high power system is proposed. The length reduction of 50 % is achieved by folding a conventional TEM horn antenna twice. The array elements are fed by the stripline power divider using the Chebyshev transformer. The power divider feeds four TEM horn antenna elements with an in-phased uniform power, and it covers a wide bandwidth ($150\;MHz\;{\sim}\;768\;MHz$, VSWR<2.0). Considering the air breakdown at peak 70 kV impulse, the proposed antenna maintains the 25 mm gaps between conducting plates. The dimension of the twice folded horn antenna is $1730\;{\times}\;1600\;{\times}\;300$ (mm3), and the operating frequency is from 152 MHz to 750 MHz under 10 dB return loss. The peak gains are measured from 6.77 dBi to 10.70 dBi at $400\;MHz\;{\sim}\;750\;MHz$.

• Analytical Science and Technology
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• v.29 no.5
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• pp.225-233
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• 2016

The chemical engrafting of polymers on particle surface, plays an important role on selective partitioning of micro/nano-particles in the separated layers of liquid media, such as aqueous two phase systems (ATPSs). Three polymers, dextran, poly (ethylene glycol) and albumin were chosen and chemically conjugated to the polystyrene (PS) magnetic microparticle surface. The attachment of long-chained polymer chains which may switch the partition behavior, can be simply performed by S_N2 substitution of various polymers having primary amine functional groups, with p-toluenesulfonyl (tosyl)-activated polystyrene magnetic micro-particles. The surface modification of microparticle was probed by infrared microscopy. The distinctive peak represents N-H stretching vibration mode for microparticles after the reaction and it is common for all three polymers examined. The locations of main peaks are similar for all micro-particles but different and distinguishable in fingerprint region.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.125-130
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• 2011

In this paper, SIW-based $2{\times}4$ uniform array antenna with a sequentially fed 8-way power divider with an equal division characteristic is proposed for an application of X-band satellite communication. In particular, sequential feeding structures with a progressive phase difference of 90 degrees between the nearest elements have been suggested to protect the cancellation of electric fields due to the array alignments and to enhance the purity of RHCP(Right-Handed Circular Polarization). The obtained results according to the return loss bandwidth, RHCP antenna gain, axial ratio bandwidth are 760 MHz ranging from 7.90 to 8.66 GHz under the criterion of less than -10 dB, 14.3 dBic at 8.3 GHz, and 600 MHz from 8.15 to 8.75 GHz, respectively. In addition, it is observed that the equal-division characteristic of SIW-based 8-way power divider is approximately -9.2 dB in all ports.

• Korea journal of population studies
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• v.28 no.2
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• pp.97-129
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• 2005

Korean society recently witnesses a rapid lllcrease of suicide across all ages. In particular, suicide in old ages jumps up ill a very unexpected way. Furthermore, the order of suicide in the cause of death across all ages is becoming higher and higher in Korea. This study provides details of suicide that occurs in Korean society with the comparison to that of Japan at the descriptive level. It is not well known why suicide in Korean surges recently. Several previous research show the possibility that surging suicide is closely related to the worsened economic conditions especially since the economic crisis in 1997. They adopt economic growth, unemployment rate, income distribution, household finance index as economic indicators in their research. This study also adopts those indicators and conducts a correlation analysis in two periods, 1990-1997 and 1998-2004. It is found that there is no correlation between economic indicators and suicide in the period of 1990-1997. On the other hand, there is a very strong correlation between income distribution and suicide in the period of 1998-2004. Other economic indicators except income distribution does not have any significant correlation with suicide. This finding suggests that currently increasing suicide in Korea may be a result of economic polarization, which has been worsened since the economic crisis in 1997.

• Journal of Soil and Groundwater Environment
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• v.13 no.2
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• pp.1-11
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• 2008

Phenanthrene uptake by surfactant sorbed on activated carbon was investigated to recycle of surfactant in washed solution for contaminated soil. The partitioning of phenanthrene to the activated carbon coating with Triton X-100 as a surfactant was also evaluated by a mathematical model. Phenanthrene-contaminated soil (200 mg/kg) was washed in 10 g/L of surfactant solution. Washed phenanthrene in solution was separated by various particle loadings of granular activated carbon through a mode of selective adsorption. Removal of phenanthrene was 99.3%, and surfactant recovery was 88.9% by 2.5 g/L of granular activated carbon, respectively. Phenanthrene uptake by activated carbon was greater than that of phenanthrene calculated by a standard model for a system with one partitioning component. This is accounted for enhanced surface solubilization by hemi-micelles adsorbed onto granular activated carbon. The effectiveness factor is greater than 1 and molar ratio of solubilization to sorbed surfactant is higher than that of liquid surfactant. Results suggest that separation of contaminants and surfactants by activated carbon through washing process in soil is much effective than that of calculated in a theoretical model.

• Applied Biological Chemistry
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• v.27 no.1
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• pp.40-44
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• 1984

Experiments on the GA production ability by ectomycorrhizal fungus, Pisolithus tinctorius was carried out to investigate specific physiological phenomena of growth increase in host plants by formation of mycorrhizae, The culture extract of P. tinctorius was purified by solvent fractionation, sephadex LH-20 chromatography, silica gel partition chromatography and TLC, successively. GA activities in the purified GA fractions were monitored by micro-drop bioassay using dwarf rice seedlings, 'Tan-ginbozu'. $30{\sim}60%$ EtOAc election fractions of silica gel pardon chromatography and the zone of Rf $0.1{\sim}0.4,\;0.6{\sim}0.8$ of TLC exhibited the GA-like activities. The GA activities were increased with the more treated amount of culture extracts. This activity in 100ml of culture solution was equivalent to 0.1ng of $GA_3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1470-1481
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• 2008

A demand for spectrum resources, especially in the low frequency bands, is ever increasing with the development of mobile telecommunications and so is their economic value as other national resources. Also, development in mobile broadband require more bandwidth with excellent propagation characteristics, such as those frequencies in the 700/800/900 MHz bands. As a way to enhance the economic efficiency of using spectrum resources, many countries including the U.S., the U.K. and Japan, have recently focused on the refarming plan of the low frequency bands according to the transition from analogue to digital TV. By the way, as a result of WRC-07, those parts of the band $698{\sim}960\;MHz$ in Region 2 and the band $790{\sim}960\;MHz$ in Regions 1 and 3 which are allocated to the mobile service on a primary basis are identified for use by administrations wishing to implement International Mobile Telecommunications (IMT). Therefore, after analogue to digital television switchover, some administrations may decide to use all or parts of the band $698{\sim}806/862\;MHz$ for other services to which the band is allocated on a primary basis, in particular the mobile service for the implementation of IMT, while in other countries the broadcasting service will continue to operate in that band. And to conclude, bands already identified for IMT-2000 will also be able to be used for IMT. This work will help establish a policy direction for spectrum refarming in the low frequency bands in Korea(Rep. of).

• Journal of Korean Society of Environmental Engineers
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• v.37 no.1
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• pp.45-51
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• 2015

PBDEs (polybrominated diphenyl ehters) are rarely dissolved in water due to their strong hydrophobicity and large molecular mass so not many researches were done in aqueous environment compared to other environmental compartments. However, the mass loading from wastewater treatment plant into aquatic environment, re-suspension from bottom sediment and partitioning from floating particles and colloids may not be negligible. It is, therefore, important but also difficult to investigate PBDEs in water environment. Recent overcoming resolution towards this barrier to monitor hydrophobic organic compounds in aquatic environment is using passive sampling technique like semipermeable membrane device. By using passive sampling, it might be possible to obtain long-term reproducible monitoring result and detect the trace amounts of PBDEs, with controlling fluctuation of surrounding environmental factors during the sampling event. So therefore, this study is purposed to confirm the possibility of using SPMD (semi-permeable membrane device) as water monitoring tool. Grab samples, composite samples and SPMDs were applied in river bank to evaluate the concentration difference and temporal fluctuation by various water sampling method, and to assess the water concentration prediction capability of SPMD for the PBDEs.