• 한국전자파학회논문지
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• 제25권11호
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• pp.1104-1112
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• 2014

위성에 활용하기 위한 전개형 경량화 안테나를 구현하기 위하여 사용되는 센서의 요구 성능을 충족하는 안테나의 설계방법을 제시하였다. 탑재되는 SAR(Synthetic Aperture Radar)의 성능을 충족하기 위한 안테나의 제반 특성과 전개방법 및 재료, 중앙판이 있는 전개형 안테나의 특성을 분석하였다. 경량화 안테나로 솔리드 전개형 안테나와 메쉬 전개형 안테나의 전개 성능을 분석하고, 사용 재료로서 CFRP(Carbon Fiber Reinforced Plastics)의 특성을 실험하였다. 중앙판이 있는 전개형 안테나의 경우, 전개 패널과 메쉬를 사용하는 경우 요구 성능을 충족할 수 있음을 확인하였다.

• 한국환경과학회지
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• 제18권4호
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• pp.355-367
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• 2009

Comparison study on the land surface temperatures, which are calculated from four different algorithms for MODIS data, was carried out and the characteristics of each algorithm on land surface temperature estimation were also analysed in this study. Algorithms, which are well used for various satellite data analysis, in the comparisons are proposed by Price, Becker and Li, Ulivieri et al., and Wan. Verification of estimated land surface temperature from each algorithm is also performed using observation based regression data. The coefficient of determination ($R^2$) for daytime land surface temperature estimated from Wan's algorithm is higher than that of another algorithms at all seasons and the value of $R^2$ reach on 0.92 at spring. Although $R^2$ for Ulivieri's algorithm is slightly lower than that for Wan's algorithm, the variation pattern of land surface temperature for two algorithms are similar. However, the difference of estimated values among four algorithms become small at the region of high land surface temperature.

• 한국습지학회지
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• 제7권4호
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• pp.89-95
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• 2005

Understanding of routes of migratory birds are important subject for conservation of avifauna. Korea Demilitarized zone (DMZ) is considered as one of the most important stopover for migratory birds that pass in the Korean peninsula. This region has been known internationally as an excellent nature preservation areas since 1953. Rare and endangered animal species such as leopards (Pathera pardus) and Siberian tigers (Panthera tigris) have increased in population. Furthermore this areas provide home for endangered migratory birds including white-naped (Grus vipio) and red-crowned cranes (G. japonensis). Recent satellite-tracked crane species has shown the importance and linkages between a small number of habitat sites in DMZ. White-naped cranes were satellite tracked 9 individuals spent 27-78% of their time in Panmunjum and 10-75% in Cheolwon. This signifies the rich feeding sites with relatively little disturbance thus making the DMZ extremely valuable as a stopover.

• 한국농림기상학회지
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• 제7권2호
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• pp.171-183
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• 2005

In order to monitor the global terrestrial carbon cycle, NASA (National Aeronautics and Space Administration) provides 8-day GPP images by use of satellite remote-sensing reflectance data from MODIS (Moderate Resolution Imaging Spectroradiometer) at l-km nadir spatial resolution since December, 1999. MODIS GPP algorithm adopts DAO (Data Assimilation Office) meteorological data to calculate daily GPP. By evaluating reliability of DAO data with respect to surface weather station data, we examined the effect of errors from DAO data on MODIS GPP estimation in the Korean Peninsula from 2001 to 2003. Our analyses showed that DAO data underestimated daily average temperature, daily minimum temperature, and daily vapor pressure deficity (VPD), but overestimated daily shortwave radiation during the study period. Each meteorological variable resulted in different spatial patterns of error distribution across the Korean Peninsula. In MODIS GPP estimation, DAO data resulted in overestimation of GPP by $25\%$ for all biome types but up to $40\%$ for forest biomes, the major biome type in the Korean Peninsula. MODIS GPP was more sensitive to errors in solar radiation and VPD than in temperatures. Our results indicate that more reliable gridded meteorological data than DAO data are necessary for satisfactory estimation of MODIS GPP in the Korean Peninsula.

• 한국항공우주학회지
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• 제33권7호
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• pp.59-69
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• 2005

본 논문에서는 위상평활화코드 기법에 기반한 실시간 동적 차분위성항법의 효율적인 구현을 위하여 위치영역 Hatch 필터를 새로이 제안하고 그 성능을 분석하였다. 제안된 위치영역 Hatch 필터는 기존의 거리영역 Hatch를 새로운 각도에서 해석하고 이를 연장하여 유도되었다. 시뮬레이션을 통하여 Hatch 이득이 Kalman 형 이득보다 더 효율적이며 또한 위성의 출몰이 빈번한 환경에서는 위치영역 Hatch 필터가 거리영역 Hatch 필터보다 유리함을 보였다.

• International Journal of Aeronautical and Space Sciences
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• 제14권3호
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• pp.282-295
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• 2013

In order to communicate with a ground station, the tracking profile design problem for a directional antenna system is considered. Because the motions of the gimbal angles in the antenna system affect the image quality, the main object is to minimize the motion of the gimbal angles during the satellite's imaging phase. For this goal, parameter optimization problems in the imaging and maneuver phases are formulated separately in the body-frame, and solved sequentially. Also, several mechanical constraints, such as the limitation of the gimbal angle and rate, are considered in the problems. The tracking profiles of the gimbal angles in the maneuver phases are designed with N-th order polynomials, to continuously connect the tracking profiles between two imaging phases. The results confirm that if the vector trace of the desired antenna-pointing vector is within the antenna's beam-width angle, motions of the gimbal angles are not required in the corresponding imaging phase. Also, through numerical examples, it is shown that motion of the gimbal angles in the imaging phase can be minimized by the proposed design process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5095-5111
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• 2019

A multi-rotor Unmanned Aerial Vehicle (UAV) system is developed to solve the manhole cover detection problem for the infrastructure maintenance in the suburbs of big city. The visible light sensor is employed to collect the ground image data and a series of image processing and machine learning methods are used to detect the manhole cover. First, the image enhancement technique is employed to improve the imaging effect of visible light camera. An imaging environment perception method is used to increase the computation robustness: the blind Image Quality Evaluation Metrics (IQEMs) are used to percept the imaging environment and select the images which have a high imaging definition for the following computation. Because of its excellent processing effect the adaptive Multiple Scale Retinex (MSR) is used to enhance the imaging quality. Second, the Single Shot multi-box Detector (SSD) method is utilized to identify the manhole cover for its stable processing effect. Third, the spatial coordinate of manhole cover is also estimated from the ground image. The practical applications have verified the outdoor environment adaptability of proposed algorithm and the target detection correctness of proposed system. The detection accuracy can reach 99% and the positioning accuracy is about 0.7 meters.

• Journal of Information Processing Systems
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• 제1권1호
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• pp.102-106
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• 2005

As long as the effective contributions of satellite images in the continuous monitoring of the wide area and long range of time period, Landsat TM and Landsat ETM+ satellite images are surveyed. After quantization and classification of the deviations between TM and ETM+ images based on approved thresholds such as gains and biases or offsets, a correlation analysis method for the compared calibration is suggested in this paper. Four time points of raster data for 15 years of the highest group of land surface temperature and the lowest group of vegetation of the Kunsan city Chollabuk_do Korea located beneath the Yellow sea coast, are observed and analyzed their correlations for the change detection of urban land cover. This experiment based on proposed algorithm detected strong and proportional correlation relationship between the highest group of land surface temperature and the lowest group of vegetation index which exceeded R=(+)0.9478, so the proposed Correlation Analysis Model between the highest group of land surface temperature and the lowest group of vegetation index will be able to give proof an effective suitability to the land cover change detection and monitoring.

• 대한영양사협회학술지
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• 제1권1호
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• pp.54-65
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• 1995

Commissary school foodservice system has been expanded rapidly in elementary foodservices in Korea. Therefore, it is essential that cost effectiveness should be assessed by comparing between alternative systems. The objectives of this study were to assess the effects on meal costs of foodservice systems and other school characteristics in terms of meal costs/day per 1 person ; to examine financial management practices and dietitians' perception concerning importance of school foodservices financial management. A total of 16 commissary schools in nationwide and 102 conventional schools at Chungnam province and Seoul were participated in this survey by mails. The results are as follows 1. Average meal costs per one person was 1,232.6 won evaluated on the standards of monthly budget basis on June, 1994. Average food costs per one person was 836.1 won(67.83%), average labor cost was 320.1 won(25.97 %) and operation costs was 76.3 won(6.2 %). 2. Average meal costs per one person did not show any significant difference between commissary and conventional foodservice schools. Meal costs of the island type and the rural type were significantly higher than those of the urban type. Meal costs of schools in Chungnam and other province were higher than schools in Seoul. The schools with less than 200 feeding numbers were higher than the schools more than 201 in meal costs per one person. 3. Food costs per one person were higher in the urban type, especially in Seoul, as the scale of feeding number increased. Labor costs and operational costs were increased in island type as well as in the schools of small feeding numbers. 4. Foodservice teachers, not dietitians were in charge of foodservice duties at the 75 % of satellites. Dietitians participated in the satellite foodservice duties were only averaged at 2.19 visits per month of 20 feeding days. 5. Items which influenced by food costs per person at the step of foodservice production were purchasing method, the perception of inventory, the distributor for foodservice, and usage of standardized recipes.

• Journal of Forest and Environmental Science
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• 제28권3호
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• pp.152-157
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• 2012

Sarawak is the largest state in Malaysia that covers 37.5% of the total land area. Multitemporal satellite images of Landsat and SPOT were used to examine deforestation and forest fragmentation in Sarawak between 1990 and 2009. Supervised classification with maximum likelihood classifier was used to classify the land cover types in Sarawak. The overall accuracies of all classifications were more than 80%. Our results showed that forests were reduced at 0.62% annually during the two decades. The peat swamp forest suffered a tremendous loss of almost 50% between 1990 and 2009 especially at coastal divisions due to intensified oil palm plantation development. Fragmentation analysis revealed the loss of about 65% of the core area of intact forest during the change period. The core area of peat swamp forest had almost completely disappeared during the two decades.