• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.43-52
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• 2000

Generally, photoelastic experimental data were measured in the closed vicinity of crack tip to determine stress intensity factors of a crack with photoelastic experiment method. In this case, only the first order term has been considered in the equation of stress field. But because it is very difficult to measure the correct photoelastic data in the closed vicinity of crack, the accuracy of experimental results was very poor. By including the high order terms in the stress field equation we could obtain the accurate S.I.F values by using clear photoelastic data in the distant region from crack tip instead of unclear photoelastic data in the vicinity of crack tip.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.964-973
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• 1997

A tidal prism eutrophication model, an one-dimensional intertidal model, is developed to study water quality conditions at small coastal basins and tidal creeks. The model simulates the physical transport processes using the concept of tidal flushing. The concept is simple and straightforward, and thus is ideal for small coastal basins with complex geometry. The model, having twenty-four state variables in the water column, simulates salinity, temperature, dissolved oxygen, three algal groups, and the cycles of carbon, nitrogen, phosphorus and silica. The model is applied to the Lynnhaven Bay, a small coastal basin of Chesapeake Bay in U.S.A. The model is calibrated using the field data collected in 1994, and then is verified using the independently collected data in 1980. The model overall gives a good reproduction of the field data, partly owing to the data collected from the field surveys specifically designed for the model application. This paper presents the procedure, and the results of the model calibration and verification.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1E
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• pp.31-37
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• 2001

Matched Field Processing (MFP) is a successive process of correcting mismatches between true and assumed parameters by matching the measured acoustic field data with numerically simulated data which we call replica. The MFP is widely used both in geo-acoustic parameter inversions and in source localizations. Whether a certain parameter can be inverted effectively or whether a source can be localized correctly depends on the amount of the influence that a parameter has on the acoustic field during the matching process. Sensitive parameters can be better estimated than the less sensitive ones in MFP. On the contrary, the sensitive parameters affect adversely on the source localization results when they have uncertainties. In this paper, a sensitivity index is defined based upon the field variation resulting from the perturbed parameters. Numerical test results show that the index behaves in accordance with the results of source localization under a mismatched environment and also with the inversion solutions.

• KIEE International Transactions on Electrophysics and Applications
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• v.12C no.4
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• pp.195-200
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• 2002

The objective of this survey is to characterize personal magnetic field exposure of the general population in Korea. The participants of the survey on magnetic field exposure were selected randomly in some occupations. The participant wore the magnetic field meter for about 25∼28 hours and the data were stored in the meter. Because this is a preliminary for the main survey, it was done with 36 participants only. For the main survey, about 400 subjects by occupation will be done. The statistics of the 24-hour exposure data are the major concern of this survey However the survey provided the opportunity to analyze exposures corresponding to different types of activities. It was analyzed by separating periods of time corresponding to the following activities: entire 24-hour period, in bed, at work and by occupation.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.2
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• pp.92-103
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• 1999

A series of field tests were performed to suggest a rational method for the stability evaluation of soft clay. The behavior of settlement-displacement obtained by field monitoring system was used to compare and analyze with various stability evaluation methods, and to investigate the applicability of the methods for stability evaluation of soft clay. The limit equilibrium method, numerical analysis and field monitoring methods were used to analyze the stability evaluation. The horizontal displacement was abruptly increased when physicla properties of soft clay reached its maximum values and therefore, the values of these properties could be used to the fundamental data for stability evaluation. The evaluation of the stability of clay embankment was suggested to use inclination of ccrve rather than critical line, and the minimum satey factor of 1.2 or larger for natural clay was recommeded . Therefore, the evaluation of short term stability of soft clay could be effectively peformed with the hypefrbolic model and the field monitored data.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.2
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• pp.87-96
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• 2005

In this research, an attempt is made to derive the practical estimation of the degree of consolidation in soft clay from field measurements under embankments. For the practical estimation of pore water pressure in soft clay, the elasto-viscous rheological model was proposed, with a transform of parameters and a field geotechnical measurements in southern Korea. By using the rheological properties of soft clays and the dissipation of excess pore water pressure behaviour during step loading, a degree of consolidation or pore water pressure estimation in the future can be performed, and are shown to be generally close to the field measurements of pore water pressure. Finally, a pore water pressure behaviour in soft clay can be explained through measured data in field and the excess pore water pressure data can also be used to estimate settlement.

• Journal of Magnetics
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• v.19 no.3
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• pp.237-240
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• 2014

For heat-assisted magnetic recording, magnetization reversal probabilities of nano-Pt/MnSb multilayer film with perpendicular magnetic anisotropy under thermal pulse activation were investigated numerically by solving the Landau-Lifshift Gilbert Equation. Magnetic parameters of nano-Pt/MnSb multilayer were used with anisotropy energy of $3{\times}10^5$ erg/cc and saturation magnetization of 2100 G, which offer more than 10 y data stability at room temperature. Scheme of driven magnetic field and thermal pulse on writing mechanism was designed closely to real experiment. This study found that the chosen material is potential to be used as a high density magnetic storage that requires low writing field less than two-hundreds Oersted through definite heating and cooling interval. The possibility of writing data with a zero driven magnetic field also became an important result. Further study is recommended on the thickness of media and thermal pulse design as the essential parameters of the reversal magnetization.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.59.2-59.2
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• 2018

Recent studies of galaxy clusters have shown that the galaxy clusters in dense environment tend to have lower star formation rate in local universe with z < 1. However, this correlation is not significant in galaxy clusters with z > 1. The study of galaxy clusters around z=1 can yield insight into cosmological galaxy evolution. Nevertheless, the identification of galaxy clusters beyond the scope of immediate local universe requires wide field data in optical and near-infrared bands. By incorporating data from Canada-France-Hawaii Telescope Legacy Survey(CFHTLS) and Infrared Medium-Deep Survey(IMS), the photometric redshifts of galaxies in CFHTLS W2 field were calculated. Using spatial distribution and photometric redshifts, the galaxies in the field were divided into redshift bins. The image of each redshift bin was analyzed by measuring the number density within proper distance of 1Mpc. By comparing high density regions in consecutive redshift bins, we identified the cluster candidates and mapped the large-scale structure within the CFHTLS W2 field.

• Agricultural and Biosystems Engineering
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• v.6 no.2
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• pp.39-46
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• 2005

Because soil compaction is a concern in crop production and environmental pollution, quantification and management of spatial and vertical variability in soil compaction for soil strength) would be a useful aspect of site -specific field management. In this paper, a soil strength profile sensor (SSPS) that could take measurements continuously while traveling across the field was developed and the performance was evaluated through laboratory and field tests. The SSPS obtained data simultaneously at 5 evenly spaced depths up to 50 em using an array of load cells, each of which was interfaced with a soil-cutting tip. Means of soil strength measurements collected in adjacent, parallel transects were not significantly different, confirming the repeatability of soil strength sensing with the SSPS. Maps created with sensor data showed spatial and vertical variability in soil strength. Depth to the restrictive layer was different for different field locations, and only 5 to 16% of the tested field areas were highly compacted.

• ETRI Journal
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• v.24 no.3
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• pp.205-210
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• 2002

This paper describes our high-density near-field optical recording using bent cantilever fiber probes installed in an atomic force microscope. We conducted a near-field reading of nano-scale hole patterns with a 100 nm spatial resolution and a 25 ${\mu}m$/s scan speed; this implies a capability of a data reading density of 60 Gb/$in^2$ with a 0.25 kbps data transfer rate. In addition, we investigated re-writable near-field recording on photochromic diarylethene films. We successfully recorded erasable memory bits having a minimum width of 600 nm in a writing time as short as 30ms. We found that using a cantilever probe simplifies the setup and operation of the near-field optical recording system and may offer multifunctional recording capabilities.