• Journal of Magnetics
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• v.8 no.3
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• pp.108-112
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• 2003

We report the experimental finding that there exists a transition of magnetization reversal process with varying the applied field in Co/Pd multilayer. We have measured the wall-motion speed V and the nucleation rate R during magnetization reversal via time-resolved direct domain observation, where the magnetization reversal process of Co/Pd multilayer is found to take a transition from thermal activation process to viscous process at the critical field of about 1.87 H$\_$C/ (coercivity). In the thermal activation regime, we find that the field dependences of two activation volumes for the wall-motion process and the nucleation process are different with each other, which reveals that the wall-motion and nucleation experience completely different interactions. In the viscous regime, we find that the wall-mobility is much smaller than a typical value for the sandwiched Co films, which implies that the Co/Pd interfaces in multilayer substantially contribute to the dynamic dissipation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.1
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• pp.9-18
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• 1999

To predict the oil spill dispersion phenomena in the ocean, the oil spill response model, which can be used for strategic purpose on the oil spill site, based on Lagrangian particle-tracking method was formulated and applied to the neighboring area with Pusan port where the oil spill incident occurred when the tanker ship No.1 Youil struck on a small rock near the Namhyungjeto on September 21, 1995. The real-time tidal currents to be required as input data of the oil spill model were obtained by the two-dimensional hydrodynamic model and the tide prediction model. Evaluation of tidal currents using observation data was successful. For wind data, other input data of oil spill model, observed data on the spot were used. To verify the oil spill model, the oil spill modelling results were compared with the field data obtained from the spill site. Compared the modelling results with the observation data, there exist some discrepancies but the general pattern of modelling results was similar to that of field observation. The modelling results on 7 days after spill occurred showed that the 40% of spilled oil is in floating, 36% in evaporated, 23% at shore, and 1% in out of boundary, respectively. According to the evaluation of weighting curves of effective components to the dispersion of oil, the winds make a 37% of contribution to the dispersion of oil, turbulent diffusion 39.5%, and tidal currents 23.5%, respectively. Provided the more accurate wind data are supported, more favorable results might be obtained.

• Fisheries and Aquatic Sciences
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• v.6 no.1
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• pp.34-40
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• 2003

Three panel trammel nets were made illegal for the brown shrimp (Penaeus japonicus) or fishes by Korean fisheries law while trammel nets for fleshy prawn in the West sea remained legal. In this study a single panel tangle net with vertical loop lines rigged between the float line and sinker line was specially designed to catch brown shrimp. This net was developed for the first time after observation of the brown shrimp behaviour when reacting to a net in an observation tank. In field experiments these single tangle nets were compared with the traditional trammel nets in the coastal waters of the Keoje area. The mean number of the brown shrimp for 53 fishing operations was 1.13 per unit panel of the single tangle nets when fitted with the vertical loop lines. This was $84\%$ of the mean catch of 1.36 achieved with the trammel nets. These results of fishing experiments using single tangle nets in the field revealed a high fishing efficiency for the brown shrimp and showed little difference from trammel nets. The size of the brown shrimp or number of by-catch was not different between single tangle nets and trammel nets.

• Journal of The Korean Association For Science Education
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• v.9 no.2
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• pp.29-45
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• 1989

The purpose of this paper is to study the operational skills of apparatuses in observation and experiments a point of view of the teaching-learning guidance of the middle school science. In order to understand the actual condition of the field learner, the achivment levels of learner have been investigated on the operational skills of apparatuses, observation and experiments through 1120 students of 16 middle schools. The results showed that there were large differences at each item and especially, in animate natural part(physics and chemistry), the handling ability was very low to average 33 percentage. By the result of analyzing the actual condition of the experiment and field science from the question of 114 science teachers who work in 40 middle schools in P distriet. it has been recognized that though the lessons through the experiments stimulate the motivation of learning, it couldn't be mamaged efficently because of all the educational conditions. And it was revealed that the major part of Experiment was performed not by student who is subjective in the course of learning but by teacher through experiments.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.105-110
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• 2011

The objective of this study is to analyze the characteristic of radiation environment in the urban and rural through the field observation in the summer. The radiation balance was compared through the measurement of the shortwave radiation and long-wave radiation in the urban, sub-urban, and rural. The following conclusion could be obtained from this research. (1) In the results of observation including the rain-day, it was found that the short wave radiance in the urban is lower about 10% than the rural. (2) The upper part of atmosphere layers in the urban area absorb much short wave radiation energies compared with the rural relatively. It can increase the temperature of the upper part of atmosphere layers and the emittance of long wave radiation. (3) The ratio of the downward short wave radiation to the downward long wave radiation was 1.24 for the urban, 1.28 for sub-urban and1.35 for rural. It can be estimated that the atmosphere condition of the rural is better than that of other areas.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.229-235
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• 2015

We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS), a Geostationary Earth Orbit (GEO) satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO) of the Korea Astronomy and Space Science Institute (KASI), Optical Wide field Patrol (OWL) at KASI, and the Chungbuk National University Observatory (CNUO) from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS) in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK) was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.

• Atmosphere
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• v.14 no.2
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• pp.7-10
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• 2004

A short review on TOTO (TOtable Tornado Observatory), one of the earliest in-situ observing systems for tornado, is provided. TOTO was outfitted with sensors for measuring wind, pressure and humidity, and storm researchers, in mid-1980's, tried to put it inside tornadoes for detailed studies on tornado, but failed. However, the accumulated knowledge and experience with TOTO lead to a successful field program in mid-1990's. A story about DOROTHY, a parody of TO TO in the movie "Twister!", is also provided.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.44.1-44.1
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• 2013

We present the preliminary results from 86 GHz GMVA observations on 2 AGN - 0954+658 and 0716+714. The observation was taken with the Global mm-VLBI Array in Oct. 2010, with dual polarization mode. The aim of the observation is to produce the polarization maps of the sources, with the Stokes parameters - I, Q, U and V. The final results will be used for estimating the strength of the intrinsic magnetic field and the geometries of AGN jets.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.11-22
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• 2001

Observations related to the along-wind dispersion of puffs were collected from 12 field sites and from a wind tunnel experiment and used to test simple similarity relations. Because most of the date made use of concentration time series observation from fixed monitors, the basic observation was t, the standard deviation of the concentration time series. This data also allowed the travel time, t, from the source to the receptor to be estimated, from which the puff advective speed ue, could be determined. The along-wind dispersion coefficient, x, was then assumed to equal tue. The data, which extended over four orders of magnitude, supported the similarity relations t=0.1 t and x=1.8 $u^*$t, where t is the travel time and $u^*$ is the friction velocity. About 50% of the observations were within a factor of two of the predictions based on the similarity relations.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.916-924
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• 2006

This research concentrates on presenting a more reasonable and engineering tunnel interpretation method with the numerical value observation data using the Hoek-Brown Model that uses mining observation data gained during construction, and the experience material constant of m and s for Seoul Underground tunnel field, which was evaluated as RMR III and RMR IV for its bedrock ratings, and by modifying and complementing the properties of ground materials with the direct method, one method in back analysis, and by using the field measurement value.