• 대한수학회보
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• 제52권2호
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• pp.453-465
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• 2015

In this paper we establish general Minkowski inequality, Aleksandrov-Fenchel inequality and Brunn-Minkowski inequality for polars of mixed complex projection bodies.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.575-578
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• 2005

Topographical images, in case of aerial or satellite images, are usually similar in colors and textures, and complex in shapes. Thus we have to use shape features of images for efficiently retrieving a query image from topographical image databases. In this paper, we propose a shape feature extraction method which is suitable for topographical images. This method, which improves the existing projection in the Cartesian coordinates, performs the projection operation in the polar coordinates. This method extracts three attributes, namely the number of region pixels, the boundary pixel length of the region from the centroid, the number of alternations between region and background, along each angular direction of the polar coordinates. It extracts the features of complex shape objects which may have holes and disconnected regions. An advantage of our method is that it is invariant to rotation/scale/translation of images. Finally we show the advantages of our method through experiments by comparing it with CSS which is one of the most successful methods in the area of shape feature extraction

• 한국군사과학기술학회지
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• 제21권1호
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• pp.17-24
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• 2018

Polar fomat algorithm (PFA) was derived from medical imaging theory, known as back projection, to process synthetic aperture radar(SAR) data. The difference between the operating condition of SAR and back projection assumption makes two distortions. First, the focusing performance of PFA is degraded in proportion to distances from the scene center. Second, the geometric accuracy in SAR images is distorted. Several methods were introduced to mitigate the distortions, but some disadvantages, such as the geometric discontinuity, are arisen when sub-images are combined. This paper proposes the novel method to compensate the geometric distortion with chirp Z-transform (CZT). This method corrects precisely the geometric errors without any problems, because a whole image can be processed all at once.

• 한국HCI학회논문지
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• 제1권2호
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• pp.27-33
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• 2006

본 논문은 회전 및 천이 불변 이미지 텍스처 검색의 새로운 방식을 소개한다. 주파수 영역의 극 좌표계에서 동일한 공간주파수에서 각도방향으로 투영을 함으로써 각도 투영법을 만들어 냈으며, 제안된 각도 투영법을 이용하여 주파수 영역에서 푸리에 계수의 합과 표준 편차를 특징벡터로 이용하였다. 각도 투영법을 쉽게 구현하기 위하여 극 좌표계에서 라돈변환이 수행된다. 실험 시 MPEG-7 데이터를 이용하였으며 그 결과는 여러 텍스처 이미지를 검 색하는데 있어서 특징을 잘 구별해 내는 결과를 보여준다. 또한 제안된 회전 및 천이불변 특징 추출 알고리듬은 등 방성 텍스처나 국부적인 방향성을 보이는 텍스처 영상 검색에서 효율적인 검색률을 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(3)
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• pp.181-184
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• 2000

In this paper, we propose new features for describing texture images by using multi-channel Gabor filter and log-polar transform based on human visual system (HVS). Gabor features are extracted by the mean and standard deviation of energy in Gabor response, followed by Fourier series extension. Log-polar features are extracted by log-polar transform and projection. The proposed texture descriptor performs reasonably well with less number of features than other texture descriptors, which has been verified by experiments using some texture images of MPEG-7 data set.

• 천문학회지
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• 제29권spc1호
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• pp.433-437
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• 1996

We have analyzed the content of the Korean stone star chart. Ch'on-Sang-Yul-Cha-Bun-Ya-Ji-Do(here-after Ch'on-Sang-Do). In the star map we have found 1468 stars, 4 more than the Chinese star catalog Bo-Chun-Ga. The four extra stars form a constellation, Jong Dae Boo. The map projection law used in the star chart is found to be the polar equtorial and equidistance projection. The linear distance of an object on Ch'on-Sang-Do from the center is linearly proportional to the north polar angular distance. We have found from a statistical analysis that most stars with declination lower than 50 are at positions representing the epoch of around the first century. On the other hand, stars near the north pole with declination higher than 50 are at the epoch of about 1300, which is close to the time the chart was engraved. This implies that the original Ko-Gu-Rye Dynasty's star chart has been revised by astronomers of Cho-Sun Dynasty. We have also shown that stars on Ch'on-Sang-Do are engraved in such a way that their area is linearly proportional to the visual magnitude.

• Ocean and Polar Research
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• 제24권3호
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• pp.255-261
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• 2002

We investigated the distribution of sea ice using Topex/Poseidon (T/P) and ERS-1 .ada. altimeter data in the northwest Weddell Sea, Antarctica, between the area $45-75^{\circ}W\;and\;55-66^{\circ}S$. Using the Geo_Bad_1 flag of the Merged GDR of the T/P, we classified the surface into ocean, land, and sea. Total 257 cycles of altimeter measurements between Oct. 1992 and Sep. 1999 (for nearly 2570 days) were used to analyze the distribution of the Antarctic sea ice. We then calculated the surface area of ice coverage using SUTM20 map projection to monitor the periodic variations. Each year, the maximum and minimum coverage of the sea ice were found in late August and February in the study area, respectively. We also studied the sea ice distribution using ERS-1 altimeter data between $45-75^{\circ}W\;and\;55-81.5^{\circ}S$ to compare with the T/P Using the Valid/Invalid flag of the Ocean Product, we analyzed the sea ice distribution between March and August of 1995, which showed very good coherence with the T/P measurements. Our preliminary results showed that the altimeter measurements can be effectively used to monitor the distribution of the sea ice in the polar region. However, the size of radar footprint, typically 2-6km depending on the roughness of the sea surface, may be too big to monitor the sharp boundary between ice and water/land. If more other altimeter mission data with dense coverage such as Geosat GM are analyzed together, this limitation can be significantly improved. If we also combine other microwave remote sensing data such as radiometer, and SSM/I, the result will be significantly enhanced.

• 대한원격탐사학회지
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• 제18권3호
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• pp.171-179
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• 2002

Sampling rates become inconsistent when spatial data in the spherical coordinate are resampled with respect to latitudinal or longitudinal degree for mathematical processes such as Fourier Transform, and this results in distortions of the processed data in the wavenumber domain. These distortions are more evident in the polar regions. An example is presented to show such distortions during the recovery process of free-air gravity anomalies from ERS-1 satellite radar altimeter data from the Barents Sea in the Russian Arctic, and a method is presented to minimize the distortion using the Lambert Conformal Conic map projection. This approach was found to enhance the free-air gravity anomalies in both data and wavenumber domains.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.212-215
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• 2008

The final product generated from the KOMPSAT-2 Terminal for Polar System, K2PS, is an ellipsoid projected image. This leaves a relief displacement on the image by process of which the height value of subject area is constant. In this paper, orthorectification using the SRTM was used to remove such artifacts, and thereafter, the additional product that could be generated from the K2PS was discussed.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2000년도 춘계공동학술발표회
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• pp.308-310
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• 2000

Sampling rates become inconsistent when spatial data in spherical coordinate are re-sampled with respect latitudinal or longitudinal degree for mathematical processes such as Fourier Transfrom, and this results in the distrtions of the processed data in the wavenmber domain. This distortions are more evident in the polar regions. An example is presented to show such distortions during the recovery process of free-air gravity anomalies from ERSI radar atimeter data in Russian Arctic Barents Sea, and a method is present to minimize the distortion using Lambect Conformal Conic map projection.