• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1034-1039
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• 1991

A robot motion planning algorithm for time-varying obstacle avoidance is proposed. The robot motion planning problem is replaced with the optimization problem by using the distance function with the divided configuration space. To divide the configuration space, the polar coordinate system is used. For each divided configuration space, the admissible region where the robot can reach without collisions is obtained using the distance function. For an object moving in a plane, the admissible region is described by linear constraints on the polar coordinate system. A numerical algorithm that solves the optimization problem is shown and the computer simulation is carried out.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2001년도 한국우주과학회보 제10권1호
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• pp.62-62
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• 2001

No Abstract, See Full Text

• 대한전자공학회논문지SP
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• 제39권4호
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• pp.455-461
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• 2002

본 논문에서는 로그폴라 (log-polar) 영상 평면에서의 Hough 변환을 위하여, 잘 알려진 unboundedness 문제를 해결하는 새로운 폴라 형태의 로그 직선 (log line) 매개변수 방정식을 제안한다. 직각 좌표상의 영상으로부터 로그폴라 영상을 생성하기 위하여, 황반부와 주변 영역으로 분리되는 Bolduc의 방법을 이용한다. 그리고 Hough 변환의 입력으로 이용되는 로그폴라 에지 영상은 Sobel 연산자로부터 추출되는 황반부 에지 영상과 본 논문에서 제안하는 공간변형 가중치가 고려된 새로운 그래디언트 연산자가 적용되어 추출되는 주변 영역을 결합하여 생성한다. 그런데 LPM (log-polar mapping; LPM)의 고유한 특성인 비선형 표본화로 인하여 시선고착점으로부터 멀리 떨어진 주변 영역에 포함되는 로그 직선들을 구성하는 화소들은 매우 산재되어 분포된다. 이러한 로그 직선들을 효과적으로 검출하기 위하여 Hough 누적 셀의 값이 공간변형 가중치가 고려되어 계산되도록 한다. 본 논문에서 제안하는 방법이 황반부와 주변 영역을 동시에 지나는 직선들뿐만 아니라 시선고착점으로부터 멀리 떨어진 주변 영역에 존재하는 직선들도 검출될 수 있음을 실험을 통하여 확인한다.

• 대기
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• 제23권3호
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• pp.331-346
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• 2013

A case study of mesoscale snowfall with polar low signature during 25~26 December 2010 in South Korea is presented. The data used for analysis include surface and upper level weather charts, rain gauge, sea surface temperature, satellite imagery, sounding, and global $1^{\circ}{\times}1^{\circ}$ reanalysis data. The system initiated with a surface trough near the bay of Bohai but quickly intensified to become a polar low within 12 hours. The polar low moved southeastward bringing snowfall to southwestern Korea. There was strong instability layer beneath 800 hPa but baroclinicty was weak and disappeared as the low progressed onto land. Shortwave at 500 hPa and the surface trough became in-phase which hindered the development of the polar low while it approached Korea. However, there were strong tropopause folding (~500 hPa) and high potential vorticity (PV), which allowed the system to maintain its structure and dump 20.3 cm of snow in Jeonju. Synoptic, thermodynamic, dynamic, and moisture analyses reveal that polar low developed in an area of baroclinicity with strong conditional instability and warm air advection at the lower levels. Further, the development of a surface trough to polar low was aided by tropopause folding with PV advection in the upper level, shortwave trough at 500 hPa, and moisture advection with low-level jet (LLJ) of 15 m $s^{-1}$ or more at 850 hPa. Maximum snowfall was concentrated in this region with convection being sustained by latent heat release.

• Ocean and Polar Research
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• 제34권1호
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• pp.101-110
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• 2012

In this study, we attempted to provide Korean names to the arctic vascular plants observed around the Dasan Korean Arctic Station and Longyearbyen in Spitsbergen Island, in the Arctic region. To obtain recognizable results, plants were named according to the following naming rules. (1) When Korean names already existed, those names were used. (2) When there was no Korean name for a plant species, a scientific name for the plant was translated into a Korean name. (3) If the meaning of the scientific name was unclear, an English common name was translated into Korean name. (4) If the scientific names had meaning to the Arctic inhabitation, the Korean names included the word 'Buk-geuk'. (5) If the distribution of the plant was limited to the Arctic area or the original species lived in the polar region, the Korean name included the word 'Buk-geuk'. (6) If the plant had no Korean generic name, a particular suffix '~a-jae-bi' was added to the closely related genus name of the plant species, or a new Korean genus name was used by translating a common English name. (7) If the same generic name had two or more Korean names, a generic name that better reflected the characteristics of the plant was selected. In this paper, we reported Korean names for 46 plants species belonging to 15 families and 28 genera. Eight plants had an existing Korean name and the other species were given new Korean names based on the criteria outlined above. We also made new Korean generic names for three genera, Braya, Micranthes and Cassiope.

• 대한기계학회논문집B
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• 제23권1호
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• pp.25-32
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• 1999

In the present paper, we theoretically analyze the flow of magnetic fluids in a circular pipe with a vertical magnetic field and investigate the magnetic response by the external magnetic field. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the Gauss Elimination Method. Using polar and magnetic effect parameters, theoretical equations and distributions for the velocity, vorticity, internal angular momentum and induced magnetization as the magnetic response are shown. Especially, in the region of strong magnetic field the specific property is appeared by finding a critical magnetic effect parameter for a polar effect parameter.

• 한국기계가공학회지
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• 제7권2호
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• pp.38-44
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• 2008

In the present paper, we theoretically analyze the flow of magnetic fluids in a circular pipe with a vertical magnetic field and investigate the magnetic response by the external magnetic field. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the Gauss Elimination Method. Using polar and magnetic effect parameters, theoretical equations and distributions for the velocity, apparent viscosity as the magnetic response are shown. Especially, in the region of strong magnetic field the specific property is appeared by finding a critical magnetic effect parameter for a polar effect parameter.

• 대기
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• 제20권3호
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• pp.367-377
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• 2010

Variation of tracer distribution during the vortex-breakup period in the Antarctic region was observed by the data from the Improved Limb Atmospheric Spectrometer (ILAS) and ILAS-II. All four trace species including methane, nitrous oxide, ozone, and water vapor show similar patterns of vertical gradient in spite of different structures of zonal mean mixing ratio. Timings of vortex breakup on each level are estimated by two different methods, and they are compared with zonal standard deviations following the latitude circle of each trace species. Although the tracers have different chemical life times and sink/source, the zonal standard deviation patterns show remarkable similarities. The zonal standard deviation shown here to measure the zonal asymmetry of tracer distribution is believed to diagnose the timing of the Antarctic polar-vortex breakup reasonably well.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.4005-4025
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• 2019

Copy-move forgery (CMF) in digital images is a detrimental tampering of artefacts that requires precise detection and analysis. CMF is performed by copying and pasting a part of an image into other portions of it. Despite several efforts to detect CMF, accurate identification of noise, blur and rotated region-mediated forged image areas is still difficult. A novel algorithm is developed on the basis of quaternion polar complex exponential transform (QPCET) to detect CMF and is conducted involving a few steps. Firstly, the suspicious image is divided into overlapping blocks. Secondly, invariant features for each block are extracted using QPCET. Thirdly, the duplicated image blocks are determined using k-dimensional tree (kd-tree) block matching. Lastly, a new technique is introduced to reduce the flat region-mediated false matches. Experiments are performed on numerous images selected from the CoMoFoD database. MATLAB 2017b is used to employ the proposed method. Metrics such as correct and false detection ratios are utilised to evaluate the performance of the proposed CMF detection method. Experimental results demonstrate the precise and efficient CMF detection capacity of the proposed approach even under image distortion including rotation, scaling, additive noise, blurring, brightness, colour reduction and JPEG compression. Furthermore, our method can solve the false match problem and outperform existing ones in terms of precision and false positive rate. The proposed approach may serve as a basis for accurate digital image forensic investigations.

• 한국지구과학회지
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• 제42권1호
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• pp.102-117
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• 2021

본 연구에서는 국내외 극지 관련 연구소 및 기관에서 운영하고 있는 극지 교육 프로그램의 교수 학습 특징을 분석하여 국내 극지 교육 프로그램에 대한 개선 방향을 제공하고자 한다. 이를 위해 극지연구소에서 제공하는 데이터베이스를 활용하여 33개국 45곳의 극지 관련 연구소 및 기관 중 최종적으로 9개국 16곳의 연구소 및 기관에서 현재 운영하고 있는 120개의 프로그램을 선정했다. 교육 대상, 교수자, 교육 기간, 교육 장소, 운영 방식, 교수 학습 내용, 교수 학습 방법을 분석 기준으로 하여 프로그램들을 분석했다. 연구 결과 교수자, 운영 방식, 교육 장소, 교수 학습 방법에서 국내외 프로그램의 유의미한 차이가 발견되었다. 이를 토대로 실제 프로그램 사례를 통해 극지 교육의 저변 확대, 극지 교육 프로그램 교육 방법의 다양화, 극지 교육의 체계화 측면에서 국내 극지 교육 개선 방향에 대해 논의했다. 본 연구는 극지에 대한 과학, 사회·경제·문화적 가치와 중요성을 토대로 우리나라의 극지 교육과 문화를 더욱 확산, 지속할 수 있는 구체적인 방안을 제시한다.