• Journal of Astronomy and Space Sciences
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• v.19 no.1
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• pp.67-74
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• 2002

Optical observations of Geostationary and Molynia orbit spin-stabilized satellites over the Korean peninsula have been carried out at the Kyung Hee University Observatory with a 30 inch telescope. We have observed 5 spin-stabilized satellites, and obtained 0spin periods, which can be used for deducing a design for each bus model. Verifications of spin periods of 3 known satellites from manufacturer, and observations of 2 unknown satellites were made. The difference between known spin periods and observed spin periods is 0.06sec on the average and the difference of those spin rates is 3.3rpm on the average. Those results indicate that spin periods and spin rates of observed geostationary spin-stabilized satellites are within operating limits. Spin rates of unknown satellites, Fengyun 2B and Molynia 1-87 are 89.3rpm, 78.4rpm earh. It is suggested that the research of spin stabilized satellites can be used for the determinations of standard light sources for short period celestial objects and helpful for the constructions of satellite databases with photometric and/or spectroscopic satellite observations.

• Cartoon and Animation Studies
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• s.31
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• pp.177-208
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• 2013

This research analyzes the media which is simultaneously used with TV viewing, the behaviour of multiple media users, and the characteristics of TV programs under Nscreen circumstances. According to the results, TV provides stories and positions it as the main screen (84.5%, n=566), under the Nscreen circumstances. Personal media reproduces stories from TV by utilizing aspects of social media functions such as participation, open communication, community, connectivity, etc. The content is classified under three categories: 1) elicit emotion(point feeling), 2) information production, 3) participation, which is further divided into three subcategories; watch, wish, and result guarantee based on the level of interactivity. This inquiry is based upon diary survey and focus group interviews emphasized the role change of TV, specifically that TV takes a key role in generating original stories with the expansion of screen and social media. Even though users were able to watch the same TV programs at the same time and same place, the different methods of viewing: smartphone, tablet PC, web based mp3 and etc., it reproduced different stories and elicited different characteristics from its TV viewers.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.683-689
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• 2012

This research was carried out to investigate the effect of installation spacing of subsurface drip irrigation pipe on the mineral content, nutrient uptake, yield of lettuce, water requirement for irrigation, and soil chemical properties in greenhouse cultivation. Semi-forcing and retarding culture were implemented in this experiment, with four treatments containing overhead spray irrigation and three subsurface irrigation lateral spacing intervals of 30, 40, 50 cm at a depth of 30 cm from soil surface, respectively. Each mineral content of lettuce grown under subirrigation system did not show significant difference between treatments, however the uptake of nutrients was lower at 50 cm-distance. The yield was largest in 30 cm-subirrigation (SI), followed by 40 cm-SI, overhead spray, and 50 cm-treatment. Water requirement for irrigation was highest in overhead spray, and it was in reverse proportion to the distance of irrigation pipes. $NO_3$-N content in the soil, at a depth of 10 cm, showed a higher value in 50 cm-SI, followed by 40 cm-SI, overhead spray and 30 cm-SI. Exchangeable K content was highest in 50 cm-SI, Mg was highest in 40 cm-SI, and Ca was lowest in 30 cm-SI. In conclusion, the lettuce yield was not different between 30 and 40 cm-SI, but water requirement for irrigation was lower as the distance of irrigation pipes was further. And it seems to be needed more precise research on this theme, because crop yield and the dynamics of soil minerals in subsurface irrigation can vary with the depth and distance of irrigation pipes, dripper, water flow depending on the soil texture, and plant response to soil minerals.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1335-1342
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• 2014

Shallow water depths were estimated using Compact Airborne Spectrographic Imager (CASI)-1500 and mapped to analyze the bottom bathymetry changes due to the rip currents in Haeundae beach, South Korea for the first time. The depths were estimated empirically using the maximum reflectances from 420nm to 597nm wavelength of CASI and 47 in situ water depth measurements, which were compared with ground-truth bathymetry measurements. The comparisons showed that the RMSE was 1.1m with a correlation coefficient of 0.76. In addition, CASI imagery showed remarkably detailed bottom features, especially those resulting from the rip currents within the beach. Two different channels carved by the rip current were analyzed and characterized with respect to the width and slope compared to surrounding regions. While the west side of the channel showed a wide and gentle slope, the east side of the channel showed a narrow and steep slope. The estimated bathymetry map revealed that the uneven offshore bottom features were related to the transport and accumulation of sediments by the rip current, which reaches hundreds of meters offshore. Accordingly, the accumulated sediments were estimated by adding topography changes compared to the depths of the non-rip current regions. The sediments were accumulated in off channels as much as almost twice the amount of annual sand supplements along the Haeundae beach.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.35-43
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• 2014

In this paper, we propose a performance enhancement method of the target tracking system for communication signal using the monopulse and the ${\alpha}{\beta}$ filter to keep the connection of the communication system between the airplane and the ground. We suggest the minimum distance measurement method for tracking error angle of the monopulse signal instead of the generally used method of MR(Monopulse Ratio) curve, and the ${\alpha}{\beta}$ filter with variable gain for enhancement of the tracking accuracy and the probability of re-tracking the monopulse signal under the disconnection of link. We show the performance enhancement of the proposed method of monopulse system using the measured MR Curve results of the prototype system. And also, the comparison of simulation results between the ${\alpha}{\beta}$ filter with variable gain and the ${\alpha}{\beta}$ filter with fixed gain shows the performance enhancement of the proposed ${\alpha}{\beta}$ filter. Using the proposed methods, we expect the enhanced performance of the existing target tracking system for communication signal only by changing the algorithm without hardware changes.

• Asian Journal of Turfgrass Science
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• v.26 no.1
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• pp.35-43
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• 2012

These studies were carried out to ascertain the effects of paraffin oil on prolongation of the green leaf color period in Zoysiagrass. Fifty-fold diluted 98% paraffin oil treatment obtained the lowest reduction rate of green color. In early October we sprayed 50-fold, 100-fold and 200-fold diluted 98% paraffin oil in a Zoysia japonica field in Hapcheon of Gyeongnam and Sangju of Gyeongbuk and in a Z. matrella field in Gumjung of Busan and Anseong of Gyeonggii. Leaf color maintained for 60 days after treatment in Zoysia japonica. Leaf color remained for 60 days after treatment in Anseong, Hapcheon and Sangju when treated in the mid-October. Chlorophyll content was higher in paraffin oil treatment areas than in control areas in early October. Weight reduction rate was lower in the paraffin oil treated than in untreated leaves of Zoysiagrass when sprayed in Gumjung and Anseong in early October and mid-October, respectively. The chlorophyll content in leaves of Z. japonica was increased by increasing the spray volume of paraffin oil in the same dose treated in Lexington, Kentucky, USA. Paraffin oil can be used to prolongate of Zoysiagrass leaf color.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.221-229
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• 2013

In this paper, the image formation by the motion compensation technique for Synthetic Aperture Radar system(SAR) were realized through the computer simulation. The motion compensation technique performed image data with the range compression, the compensation procedure, the azimuth compensation and the noise elimination procedure. The range compression procedure transform the SAR raw data into the frequency domain and correlate with the range reference function and then inversely transform into the time domain. The compensation procedure contain the aircraft fluctuations compensation and the radar image degrading effect elimination procedure which was caused by image formation algorithm itself. The aircraft fluctuations compensation procedure perform the first stage which correct the phase angle and the second stage which calculate the Doppler frequency and determine the coordinate of the received signal. The radar image degrading effect elimination procedure also perform range migration compensation and the image defocussing effect compensation. The azimuth compression procedure transform the compensation data to the frequency domain and correlate with the azimuth reference function. The azimuth correlated data are inversely transformed to the time domain which is called SAR image data. When the above procedure were completed, the image data contains the received signals mixed with noise. The threshold technique was applied to elimination the noise from the mixed image data.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.229-233
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• 2010

This experiment was carried out to find optimum ratio of $NO_3^-$ to $NH_4^+$ in nutrient solution for the growth of Phalaenopsis hybrid and find the effect of the ratio of $NO_3^-$ to $NH_4^+$ on the flower stem (inflorescence) quality. The ratio of $NO_3^-$ to $NH_4^+$ of nutrient solution used in this experiment was 100% : 0%, 90% : 10%, 80% : 20% and 70% : 30%. Phalaenopsis showed better growth when $NH_4^+$ was supplied concurrently with $NO_3^-$ as nitrogen source than supplied with only $NO_3^-$. Especially, increasing the ratio of $NH_4^+$ from 0% to 10% the fresh weight and dry weight of Phalaenopsis hybrid was highest. But, the growth of shoot and root was diminished when the proportion of $NH_4^+$ in nutrient solution was increased from 10% to 30%. Inflorescence length, the number of inflorescence and flower per plant all increased as $NH_4^+$ increased from 0% to 10% but, decreased from 10% to 30%. These results suggest that the optimal ratio of $NO_3^-$ and $NH_4^+$ in nutrient solution for the growth of Phalaenopsis including inflorescence was founded to be 90%:10%.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.255-261
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• 2016

The present study was conducted to characterize physiological responses of aerial part according to soil water stresses in 'Mihong' peach trees. Discolorations, wilting and falling of leaves were observed in chronological order as response for waterlogging and no irrigation and the phenomena started from basal to end of shoots. Shoot growth in elongation and thickness decreased and fallen leaves were severe in waterlogged trees. Function of water uptake by roots and photosynthesis and leaf respiration decreased by waterlogging. Leaf chlorophyll contents decreased in both treatments. In waterlogging treatment, decrease of chlorophyll was observed in normal leaves with waterlogging using light microscopy. Starch content was lower in both treatment and carbohydrate content was lower in root with waterlogging. These results demonstrated that waterlogging weakened the function of soil water uptake and movement and decreased photosynthesis and fallen leaves. Finally the peach trees would wither or suffer low temperature damage through the shortage of reserve accumulations. We suggested that waterlogging damage in peach trees could be reduced to take notice of irrigation and install drainage facility to improve soil condition.

• Fire Science and Engineering
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• v.24 no.5
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• pp.50-59
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• 2010

Four fire scenarios, as the cases of fire sizes of 2 MW and 5 MW, and no installation and activation of atrium fire shutter for dormitory building of Daegu 'D college', were developed and fire simulations were run using FDS (ver. 5.5.0) and Pathfinder 2009 programs. By assessing fire and evacuation, the effects of atrium fire shutter and vents on the smoke control of atrium were evaluated and this study also analyzed fire hazard and egress safety for occupants in the dormitory. Fire shutter's preventing smoke transport around atrium was much effective, but smoke layer descended down the design limit of smoke height and kept about 2 m height from the atrium floor in all cases because flow rate through vents was not enough. For the case of 5 MW fire and no fire shutter, fire hazard was higher due to visibility than temperature and allowable egress time to stairwell was short less than 5 seconds for the occupants on the floors of 4F to 7F. For total occupants, egress time out of main doorway was calculated about 136 seconds. It is sure that additional systems improving the performance of smoke control need to be installed for more safe evacuation.