• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.106-109
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• 1999

The problem of electromagnetic field through apertures in cavity has been theoretically and experimentally investigated. The electric field intensity has been theoretically evaluated by the method of moments. Experiment results are some different from numerical simulation about the magnitude of electric field intensity, But The form of electric field intensity distributions In cavity is similar to numerical simulation. Reactance-loaded method for reducing electric field penetration In cavity by external sources is used In this paper.

• Applied Microscopy
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• v.36 no.spc1
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• pp.63-69
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• 2006

By utilizing a field emission gun and a biprism installed on a transmission electron microscope (TEM), electron holography is extensively carried out to visualize the electric and magnetic fields of nanomaterials. In the electric field analysis, the distribution of electric potential in a sharp tip made of W coated with $ZrO_2$ is visualized by applying the voltage to the tip. Denser contour lines due to the electric potential are observed with an increase in the bias voltage. In the magnetic field analysis by producing the strong magnetic field with a sharp magnetic needle made of a permanent magnet, the in situ experiment is carried out to investigate the magnetization of hard magnetic materials. The results of these experiments clearly demonstrate that electron holography is a promising advanced transmission electron microscopy technique to characterize the electric and magnetic properties of nanomaterials.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1180-1182
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• 2003

In Asian countries, paddy field is indispensable for our lives not only as a source of food but also ecosystem, hydrology, landscape, culture and global warming. In this sense it is necessary to get the detailed spatial distribution of paddy field in Asian region. Remote sensing seems to be the most appropriate tool to estimate paddy field. In this study, two Terra/ASTER images acquired on different date were used to get a map of paddy field with different planting. ASTER's 15-m resolution was found to be enough to be recognize individual paddy field . Paddies with different planting stages were divided into five types using their spectral patterns. As a result a map of paddies with different planting was obtained with tolerably high accuracy.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.3
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• pp.237-246
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• 2010

This study was conducted to evaluate growth characteristics and yield of silage corn hybrids by different planting dates at paddy and upland field. Days to silking by different planting dates at paddy field were 81 days at planting on April 22, 70 days on May 20 and 62 days on June 10, respectively, and they were getting shorter as planting date delayed. There was no significant difference in days to silking between paddy and upland field. Plant height in paddy field was no significant difference between at planting on April 22 and on May 20, and it was shortened sharply at planting on June 10. There was no significant difference in plant height between paddy and upland field. There was no significant difference in lodging by different planting dates in paddy field. There was significant difference in lodging between paddy and upland field (P<0.05). There was no significant difference in stay-green by different planting dates in paddy field, and no significant difference between paddy and upland field. Ear ratios to total dry matter in paddy field were 43% at planting on April 22, 41% on May 20 and 28% on June 10, respectively, and it was lower as planting date delayed. There was no significant difference in ear ratios to total dry matter between paddy and upland field. Fresh yields in paddy field were lower with 14% at planting on May 20 and 32% on June 10 compared to on April 22 as planting date delayed. There was no significant difference in fresh yield between paddy and upland field. Dry matter yields in paddy field were higher with 9% at planting on May 20 and lower with 24% on June 10 compared to at planting on April 22 as planting date delayed. Dry matter yield in paddy field was lower with 9% compared to 1,931 kg/10a at planting on April 22. TDN (Total digestible nutrients) yields in paddy field were higher with 5% at planting on May 20 and lower with 28% on June 10 compared to at planting on April 22 as planting date delayed. TDN yield in paddy field was lower with 11% compared to 1,340kg/10a at planting on April 22.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.2
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• pp.28-38
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• 2000

The aim of this study is evaluate artificial soils which are used alone or in a blend with field soil for the greening of artificial ground. To achieve these, determination of physicochemical properties was made in four artificial media[Perlite small grain(PSG), perlite large grain(PLG), crushed porous glass+bark(AS), crushed porous glass(CPG)] used alone and/or in a blend with field soil, then evaluation of their effect on th plant growth of Ligustrum obtusifolium and Syringa vulgaris were conducted. In bulk density of root media at field capacity and the saturated hydraulic conductivity, LG and AS showed good performance. But, PLG was though to be unsuitable as artificial soil when used alone because of poor plant growth. PLG, AS, and CPG were thought to be good when it is used in a blend with field soil. But, PSG was thought to be unsuitable. In the result, PSG is recommended as artificial soil which is used alone for greening of artificial ground. PLG is recommended as artificial soil which is used in a blend with field soil. AS is recommended as artificial soil which is used alone and in a blend with field soil. Thought CPG+field soil(v/v, 1:1) might be undesirable in consideration of the chemical properties in six months after planting, it was thought to be superior to th other treatments in the plant growth. CPG can be used as artificial soil which is used in a blend with field soil. Follow-up studies are being conducted to investigate their effects on the plant growth of the other plants and the practical use of them in artificial grounds.

• Animal cells and systems
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• v.8 no.4
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• pp.281-288
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• 2004

The change in relationships between methane production and sulfate reduction was investigated in reclaimed rice field soils at different time points after reclamation of tidal flat in Korea. Sulfate concentrations of soils in the ca. 60-year-old and 26-year-old reclaimed rice fields were much lower than that in a natural tidal flat. During 60 d of anaerobic incubation, total methane production and sulfate consumption of the soil slurries were 7.0 ${\mu}$mol $CH_4$/g and 8.2 ${\mu}$mol $SO_4^{2-}$/g in the 60-year-old rice field, 5.6 ${\mu}$mol $CH_4$/g and 12.7 mmol $SO_4^{2-}$/g in the 26-year-old rice field, and ca. 0 mmol $CH_4$/g and 22.4 ${\mu}$mol $SO_4^{2-}$/g in a natural tidal flat. Relative percent electron flow through sulfate reduction in the 60-year-old rice field was much lower (50.8%) compared with the 26-year-old rice field (69.3%) and the tidal flat (99.9%). The addition of an inhibitor of methanogenesis (2-bromoethanesulfonate) had no effect on sulfate reduction in the soil slurries of the reclaimed rice fields. However, instant stimulation of methane production was achieved with addition of an inhibitor of sulfate reduction (molybdate) in the soil slurries from the 26-year-old reclaimed rice field. The specific inhibitor experiments suggest that the relationship of methanogenesis and sulfate reduction might become mutually exclusive or syntrophic depending on sulfate content in the soil after reclamation. Sulfate, thus sulfate reduction activity of sulfate-reducing bacteria, would be an important environmental factor that inhibits methane production and determines the major pathway of electron and carbon flow in anaerobic carbon mineralization of reclaimed rice field soils.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.3 s.309
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• pp.76-81
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• 2006

Recently, Finite field is applied the cryptography in the modern multimedia communication. Especially, block codes such as Elliptic Curve Cryptosystem and Reed-Solomon code among the error correcting codes are defined with finite field. Also, finite field algorithm is conducting the research actively because many kind of application parts need the real time operating ability therefore the exclusive hardware have been implementing. In this paper, we proposed the inverse finite field algorithm over GF($2^8$) using finite composite field and implemented in a hardware, and then compare this hardware with the currently used 'Itoh and Tsujii' hardware in respect to structure, area and computation time. Furthermore, this hardware was inserted into the AES SubBytes block and implemented on FPGA emulator board to confirm that the superiority of the proposed algorithm through the performance evaluation.

• Journal of Environmental Science International
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• v.20 no.1
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• pp.107-118
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• 2011

While the assessment of mean flow field is very important to characterize the hydrodynamic aspect of the flow regime in river, the conventional methodologies have required very time-consuming efforts and cost to obtain the mean flow field. The paper provides an efficient technique to quickly assess mean flow field by developing and applying spatial averaging method utilizing repeatedly surveyed acoustic Doppler current profiler(ADCP)'s cross-sectional measurements. ADCP has been widely used in measuring the detailed velocity and discharge in the last two decades. In order to validate the proposed spatial averaging method, the averaged velocity filed using the spatial averaging was compared with the bench-mark data computed by the time-averaging of the consistent fix-point ADCP measurement, which has been known as a valid but a bit inefficient way to obtain mean velocity field. The comparison showed a good agreement between two methods, which indicates that the spatial averaging method is able to be used as a surrogate way to assess the mean flow field. Bed shear stress distribution, which is a derived hydrodynamic quantity from the mean velocity field, was additionally computed by using both spatial and time-averaging methods, and they were compared each other so as to validate the spatial averaging method. This comparison also gave a good agreement. Therefore, such comparisons proved the validity of the spatial averaging to quickly assess mean flow field. The mean velocity field and its derived riverine quantities can be actively used for characterizing the flow dynamics as well as potentially applicable for validating numerical simulations.

• Journal of Environmental Science International
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• v.17 no.7
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• pp.817-826
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• 2008

Using high voltage electric fields induced by high voltage AC (10-12 kV/cm, 20 kHz) and pulsed (20-30 kV/cm, 40 Hz) electric field generator as a semipermanent and environment-friendly disinfecting apparatus, the disinfection effect of coliform group in the effluent of sewage plant was investigated. The effects of electric field strength, treatment time, discharge area of a discharge tube, water quality factors (electric conductivity, pH and SS) on its death rate were examined. The death rate of coliform group was increased with increasing electric field strength and treatment time. For AC and pulsed electric field generator, the critical electric field strength was 6 kV/cm and 2 kV/cm, respectively, and the critical treatment time was 5 min and 2 min, respectively, regardless of electric field strength. Comparing the death rate of coliform group by AC and pulsed electric fields used in this study, its death rate was higher for the latter than the former, but did not increase linearly with increasing electric field strength. The results obtained for the effects of discharge area, electric conductivity, pH and SS on the death rate of coliform group using AC electric field (12 kV/cm, 20 kHz) were as follows: its death rate showed the trend to increase linearly with increasing discharge area; for the effect of electric conductivity, its death rate was increased with increasing electric conductivity, regardless of ionic species, increased with increasing cationic valency, but was similar between the same cationic valency; the pH $5{\sim}9$ used in this study did not affect its death rate; its death rate was decreased with increasing SS concentration.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.4
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• pp.111-119
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• 2012

Time Stretched Pulse (TSP) is used for transmitting and analyzing the impulse signal over the designated spatial place. However, if transfer functions of transmitter and receiver are unknown, performance investigation of free field in temporal domain is barely possible due to the overlap between the direct and indirect signal from the space. Generally, the free field or hemi-free field is evaluated by the Annex A of ISO 3745 in which utilizing the inverse square law with one-third octave band signals. In this paper, the author performs analysis of free field via applying TSP with inverse square law and the results are compared with the one-third octave band signals. According to the analysis of deviation between the corresponding signal and inverse square law model, the proposed TSP method provides the comparable performance index to the one-third octave band signal with reduced measuring time. Provided that the pre-whitening can be implementable by employing the speaker and microphone transfer function, further analyses from TSP compression are able to be performed such as multipath separation from time domain data. The anechoic chamber used in this experiment is verified conformance with ISO 3745 for free field and hemi-free field condition for limited frequency of the signal.