• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.615-620
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• 2002

Probability distribution of the sea surface slope is estimated using sun glitter images derived from visible radiometer on Geostationary Meteorological Satellite (GMS) and surface vector winds observed by spaceborne scatterometers. The brightness of the visible images is converted to the probability of wave surfaces which reflect the sunlight toward GMS in grids of 0.25 deg $\times$ 0.25 deg. Slope and azimuth angle required for the reflection of the sun's ray toward GMS are calculated for each grid from the geometry of GMS observation and location of the sun. The GMS images are then collocated with surface wind data observed by three scatterometers. Using the collocated data set of about 30 million points obtained in a period of 4 years from 1995 to 1999, probability distribution function of the surface slope is estimated as a function of wind speed and azimuth angle relative to the wind direction. Results are compared with those of Cox and Munk (1954a, b). Surface slope estimated by the present method shows narrower distribution and much less directivity relative to the wind direction than that reported by Cox and Munk. It is expected that their data were obtained under conditions of growing wind waves. In general, wind waves are not always developing, and slope distribution might differ from the results of Cox and Munk. Most of our data are obtained in the subtropical seas under clear-sky conditions. This difference of the conditions may be the reason for the difference of slope distribution.

• 대한원격탐사학회지
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• 제26권3호
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• pp.347-359
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• 2010

Ortho-photos provide valuable spatial and spectral information for various Geographic Information System (GIS) and mapping applications. The absence of relief displacement and the uniform scale in ortho-photos enable interested users to measure distances, compute areas, derive geographic locations, and quantify changes. Differential rectification has traditionally been used for ortho-photo generation. However, differential rectification produces serious problems (in the form of ghost images) when dealing with large scale imagery over urban areas. To avoid these artifacts, true ortho-photo generation techniques have been devised to remove ghost images through visibility analysis and occlusion detection. So far, the Z-buffer method has been one of the most popular methods for true ortho-photo generation. However, it is quite sensitive to the relationship between the cell size of the Digital Surface Model (DSM) and the Ground Sampling Distance (GSD) of the imaging sensor. Another critical issue of true ortho-photo generation using high resolution satellite imagery is the scan line search. In other words, the perspective center corresponding to each ground point should be identified since we are dealing with a line camera. This paper introduces alternative methodology for true ortho-photo generation that circumvents the drawbacks of the Z-buffer technique and the existing scan line search methods. The experiments using real data are carried out while comparing the performance of the proposed and the existing methods through qualitative and quantitative evaluations and computational efficiency. The experimental analysis proved that the proposed method provided the best success ratio of the occlusion detection and had reasonable processing time compared to all other true ortho-photo generation methods tested in this paper.

• 한국물환경학회지
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• 제35권1호
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• pp.1-8
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• 2019

The purpose of this study is to evaluate the nutritional status of Lake Jinyang using Landsat 8 satellite image band correlated with chlorophyll-a, which is also related to algae proliferation. We selected 20 Landsat 8 images dating from 2013 to 2017, taken close to water quality measurement date when the cloud cover was less than 20 %. Based on the results of the previous studies, analyzing the correlation between chlorophyll-a, and Landsat 8 satellite image band, we selected near infrared wavelength, band 5 which is closely related to the population of algae. The nutritional status was classified using the Aizaki trophic state index (TSIm). The results of the regression equation between band 5 and the observed chlorophyll-a data was used to calculate chlorophyll-a for the image data from 2013 to 2017. The concentration of chlorophyll-a ranged from 3 to $16.1mg/m^3$. To illustrate the spatial distribution of chlorophyll-a within the lake, the chlorophyll-a concentration was divided into five grades. The images on October 14, 2014 and April 10, 2016 showed relatively high value of chlorophyll-a, while January 18, 2015 and December 6, 2016 chlorophyll-a value were below 5. The images on October 14, 2014 and April 10, 2016 were rated as eutrophic status in most areas. The results of simulating water quality for the day when the water quality was not measured resulted to an approximate value for the Panmun station while the Naedong station needed some corrections.

• 한국전자통신학회논문지
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• 제18권3호
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• pp.545-554
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• 2023

현대 산업에서 위성항법시스템(Global Navigation Satellite System : GNSS)은 PNT 정보(측위(P : Positioning), 항법(N : Navigation), 시각동기(T : Timing))가 항상 제공되어야 하고, 그 정보를 기반으로 정밀한 위치추정이 요구되는 다양한 분야에 활용되고 있다. 특히, 2019년부터 시작된 COVID-19 펜데믹 상황에 대한 감염 예방 및 확산 방지를 위해 정밀한 위성항법시스템 기술과 이를 보조하는 다양한 기술들이 사용되어 왔고, 전 세계의 적극적인 방역과 감염 확산 억제 노력으로 엔데믹 상황으로의 전환을 앞두고 있다. 질병, E-health 분야는 감염병의 추적 및 감시와 더불어 원격 의료 서비스 제공을 위해 이용자의 위치정보가 반드시 필요한데, 위성항법시스템이 정확한 위치정보 제공에 주도적인 역할을 하고 있다. 본 논문은 이러한 위성항법시스템 기술이 질병 및 E-health 분야에 활용된 최신 연구 동향에 대해 조사한 결과를 제시하고 그 결과를 분석한다.

• 한국농공학회논문집
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• 제65권6호
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• pp.79-91
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• 2023

This study surveyed the actual status of reclamation areas in South Pyongan Province, North Korea, using satellite images and literature to survey the creation date, area, and length of the embankment of the reclamation areas. The reclamation areas in South Pyongan Province were created in three stages, with the first stage completed in the late 1970s or early 1980s, the second stage in the late 1980s or early 1990s, and the third stage in the 2000s. The total area of the reclamation areas is 105,570 hectares. The land cover of the reclamation areas is as follows: agriculture (50.5%), saltern (29.5%), water bodies (13.6%), foreshore (12.4%), grasslands (3.0%), bare land (0.4%), facility (0.1%), and forests (0.1%). The study also found that the NDVI values of the reclamation areas vary depending on the location. The NDVI values of the Gwiseong and Namyang reclamation areas are low, while the NDVI values of the Samcheonpo and Jigdongbaedali reclamation areas are high. The study found that the NDVI values of the reclamation areas are correlated with the land cover of the reclamation areas. The study's findings can be used to understand the development direction and regional characteristics of the reclamation areas in South Pyongan Province. The study's findings can also be used to develop policies and plans for the sustainable development and utilization of the reclamation areas in South Pyongan Province.

• 한국전자통신학회논문지
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• 제18권6호
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• pp.1057-1066
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• 2023

위성항법시스템(Global Navigation Satellite System : GNSS)은 4차 산업혁명의 핵심 기술 중 하나로, 정확한 위치정보가 필요한 차세대 이동통신과 스마트 모빌리티 분야에서 그 중요성이 더욱 부각되고 있다. 고성능/고정밀 위성항법시스템 기술의 발달로 보다 정확한 위치정보 획득이 가능해짐에 따라 사용자들에게 고품질의 서비스를 제공할 수 있는 다양한 위치기반 제품 및 시스템들이 연구/개발 되고 있다. 본 논문은 차세대 이동통신 및 스마트 모빌리티 분야에 위성항법시스템 기술이 활용된 최신 연구 동향과 사례에 대해 조사한 결과를 제시하고, 그 결과를 분석한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.772-775
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• 2006

Muilti-dimensional feature vector matching algorithm uses multiple features such as intensity, gradient, variance, first or second derivative of a pixel to find correspondence pixels in stereo images. In this paper, we proposed a new method for adjusting automatically the weight of feature in multi-dimensional feature vector matching considering sharpeness of a pixel in feature vector distance curve. The sharpeness consists of minimum and maximum vector distances of a small window mask. In the experiment we used IKONOS satellite stereo imagery and obtained accurate matching results comparable to the manual weight-adjusting method.

• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.87-92
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• 2002

A short-ended electromagnetically coupled coaxial dipole array antenna is investigated theoretically. The antenna has an advantage of structural simplicity. The integral equations are derived for the proposed structure by use of the Fourier transform and mode expansion, and the simultaneous linear equations are obtained. The slot electric field and strip current are obtained by solving the simultaneous linear equations. The effects of slot and strip numbers on the radiation efficiency, beamwidth and directivity gain of the antenna are presented.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.403-404
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• 2006

In this paper, we proposed muli-dimensional feature vector matching method combined with disparity smoothness constraint. The smoothness constraint was calculated using the difference between disparity of center pixel and those of 4-neighbor pixels. By applying proposed algorithm to IKONOS satellite stereo imagery, we obtained robust stereo matching result in urban areas.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.634-637
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• 2002

In order to contribute to trial of the ocean weather forecasts, we have developed new generation sea surface temperature. It is clod free, high-spatial resolution daily SST product, which enables us to follow the movements of SST patterns relating to the oceanic variations. The product is produced through an objective analysis merging various infrared and microwave SST products.