• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.326-327
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• 2015

본 논문에서는 화재의 움직임 정보에 기반하여 역동적인 화재를 감지하는 기법을 제안한다. 우선 감시 카메라와 같은 고정형 감시 장치로부터 얻어진 색 정보를 분리하기 쉬운 좌표계로 변환하고 이전에 수집된 데이터들로부터 얻어진 사전 정보로부터 화염 영역을 추출한다. 또한 화염 영역의 가장자리가 움직임이 매우 크다는 사실에 기반하여 광흐름 벡터로 얻어진 시간적 분산값을 이용한 움직임 모델을 생성한다. 화염 영역은 움직임 모델과 결합되며 오탐을 걸러내기 위해 충분한 양의 화재 영역이 중첩될 때 최종적으로 화재를 판별한다. 본 논문에서 제안한 방법은 실험 결과에서 우수한 탐지 능력을 보인다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.247-249
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• 2017

NIST에서 표준으로 정의된 P-192, P-224, P-256, P-384 타원곡선 상의 스칼라 곱셈(scalar multiplication) 연산을 지원하는 Scalable 타원곡선 암호(Elliptic Curve Cryptography; ECC) 프로세서의 설계에 대해 기술한다. 투영(projective) 좌표계를 이용하여 하드웨어 자원 소모가 큰 나눗셈 연산을 제거하였으며, GF(p) 상의 덧셈, 뺄셈, 곱셈 등의 유한체 연산을 지원한다. 워드 기반 몽고메리 곱셈기를 이용하여 다양한 크기의 필드(field)에서 고정된 하드웨어 자원을 통하여 곱셈 연산을 수행하도록 하였으며, 필드의 크기에 따라 연산 사이클이 증가하거나 감소한다. 설계된 Scalable ECC 프로세서는 Verilog HDL로 모델링 되었으며, Modelsim을 이용한 기능검증을 하였다. Xilinx Virtex5 FPGA 디바이스 합성결과 5,376-비트 RAM과 970 슬라이스로 구현되었으며, 최대 55 MHz의 동작 주파수를 갖는다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.552-553
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• 2014

본 논문은 인버터 독립운전모드에서의 출력 전압 제어 방식을 다루고있다. 본 논문은 계통 연계 모드와 독립 운전 모드간의 모드 절환이 가능한 계통 연계형 인버터 출력단에 비선형 불평형 부하 연결시 발생하는 출력전압 왜곡현상에 대처하기위해 기존에 주로 사용되는 PI 제어를 이용한 방식을 대신해 고정좌 좌표계 또는 abc natural 프레임 하에서 사용되는 PR 제어를 사용하여 고조파 보상을 수행하였으며 추가적으로 계통 연계 모드시 외부 PR 출력 전류 루프와 내부 PR 출력 전압 루프를 가지는 제어기를 제안하였고 이러한 제어 방식이 계통 연계 모드의 출력 전압 THD 성능개선에 효과적임과 동시에 또한 모드 변환시의 동특성을 좀더 개선할 수 있다는 점을 입증하였다.

• Journal of Radiation Protection and Research
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• v.17 no.1
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• pp.43-56
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• 1992

As one of the methods to ameliorate the ray effects which are the nature of anomalous computational effects due to the discretization of the angular variable in discrete ordinates approximations, a computational program, named TWODET (TWO dimensional Discrete Element Transport), has developed in 2 dimensional cartesian coordinates system using the discrete elements method, in which the discrete angle quadratures are steered by the spatially dependent angular fluxes. The results of the TWODET calculation with K-2, L-3 discrete angular quadratures, in the problem of a centrally located, isotropically emitting flat source in an absorbing square, are shown to be more accurate than that of the DOT 4.3 calculation with S-10 full symmetry angular quadratures, in remedy of the ray effect at the edge flux distributions of the square. But the computing time of the TWODET is about 4 times more than that of the DOT 4.3. In the problem of vacuum boundaries just outside of the source region in an absorbing square, the results of the TWODET calculation are shown severely anomalous ray effects, due to the sudden discontinuity between the source and the vacuum, like as the results of the DOT 4.3 calculation. In the probelm of an external source in an absorbing square in which a highly absorbing medium is added, the results of the TWODET calculation with K-3, L-4 show a good ones like as, somewhat more than, that of the DOT 4.3 calculation with S-10.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.221-227
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• 2010

Recent development in seeker technology explores a new seeker design in which, with larger field-of-view (FOV), optical parts are strapped down to a body (hence, called as a body-fixed seeker or a strapdown seeker). This design has several advantages such as comparatively easier maintenance and calibration by removing complex mechanical moving parts, increasing reliability, and cost savings. On the other hand, the strapdown seeker involves difficulties in implementing guidance laws since it does not directly provide inertial LOS rates. Instead, information for generating guidance commands should be extracted by estimating missile/target relative motion utilizing target images on the image plane of a strapdown seeker. In this research, a new framework based on an unscented Kalman filter is developed for estimating missile/target relative motion on the simplified assumption of a point source target. Performance of a terminal guidance algorithm, in which guidance command is generated based on the estimated relative motion, is demonstrated by a missile/target engagement simulation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.273-279
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• 2011

Turbulent flow analysis around a wind turbine blade was performed to evaluate the power performance of offshore wind turbine. Fluent package was utilized to solve the Reynolds-averaged Navier-Stokes equations in non-inertial rotating coordinates. The realizable k-$\varepsilon$ model was used for turbulence closure and the grid system combining structured and unstructured grids was generated. In the first, lift and drag forces of 2-D foil section were calculated and compared with existing experimental data for the validation. Then torque and thrust of the wind turbine blade having NACA 4-series sections were calculated with fixed pitch angle and rpm. Tip speed ratio was varied by changing wind speed. In the next, three kinds of end plate were attached at the tip of blade in order to increase the power of the wind turbine. Among them the end plate attached at the suction side of the blade was found to be most effective. Furthermore, performance analysis with tilt angle and rake was also performed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.167-173
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• 2011

This paper analyzes the procedure of calculating how the results of national control points (triangulation points), based on Bessel datum, have been transformed into those of KGD2002, based on the world geodetic system. GPS and EDM data observed from 1974 to 2008 were used for this purpose. A large-scale integrated GPS network was constructed to estimate the results of KGD2002 and new national control points about 12,000 were decided through multiple stages of data processing. The accuracy of these results is ${\pm}0.015m$ (95%) in the horizontal direction and ${\pm}0.030m$ (95%) in the vertical direction. The adjusted results verified by the construction of an integrated GPS/EDM network were compared with the results of KGD2002. In conclusion, the bulletin results are thought to be appropriate because the coordinate differences (RMSE) are ${\pm}0.0025m$ and ${\pm}0.008m$ in horizontal and vertical directions respectively.

• Progress in Medical Physics
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• v.8 no.1
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• pp.17-24
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• 1997

We developed PC-based planning system for linear accelerator based stereotactic radiosurgery. The system was developed under Windows 95 on Pentium Pro$\^$(R) 200 ㎒ IBM PC with 128 MB RAM. It was programed using IDL$\^$(R)/ of Research Systems, Inc. as a programing tool. CT image data obtained with BRW stereotactic frame is transferred to PC through magnetoptical disk. As loading the image, the system automatically recognizes the location of rods and establishes stereotactic coordinates. It accurately calculates and corrects the coordinates, degree of tilting, and magnification rate of axial images. After the coordinates is defined we can delineate and edit the contours of target and organs of interest on axial images. Upon delineating contours of target, isocenter is determined automatically and we can set up the beam configuration for radiosurgery. The system provides beam's eye view and room's eye view for efficient confuguring of beams. The system calculates dose distribution 3-dimensionally. It takes 1 to 2 minutes to calculate dose distribution for 5 arcs. We can verify the dose distribution on serial axial images. We can analyze the dose distribution quantitatively by evaluation of dose-volume histogram of target and organ of interest. This system, PC-based radiosurgery planning system, includes the basic features for radiosurgery planning and calculates dose distribution within reasonable time for clinical application.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.220-227
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• 2019

The satellites in orbit use a sun reference vector from solar model based the ephemeris. To get the ephemeris, we use DE-Series, an ephemeris developed by the Jet Propulsion Laboratory (JPL), or the reference vector generation formula proposed by Vallado. The DE-Series provides the numerical coefficients of Chebyshev polynomials, which have the advantage of high precision, but there is a computational burden on the satellite. The Vallado's method has low accuracy, although the sun vector can be easily obtained through the sun vector generation equation. In this paper, we have developed a program to provide the Chebyshev polynomial coefficients to obtain the sun position coordinates in the inertial coordinate system. The proposed method can improve the accuracy compared to the conventional method and can be used for high - performance, high - precision nano satellite missions.

• Journal of Korea Water Resources Association
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• v.41 no.8
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• pp.855-862
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• 2008

Surface Image Velocimetry (SIV) is an instrument to measure water surface velocity by using image processing techniques. To improve its measuring accuracy, it is essential to get high quality images with low skewness. A truck-mounted SIV system would be a good way to get images, since its crane gives high altitude to the images. However, the images taken with a truck-mounted SIV would be swayed due to the movement of crane and the camera by winds. In that case, to analyze the images, it is necessary to compensate the side sway in the images. The present study is to develop an algorithm to analyze the swayed images by combining common image processing techniques and coordinate transform techniques. The system follows the traces of some selected fixed points and calculates the displacements of the video camera. By subtracting the average velocity of the fixed points from that of grid points, the velocity fields of the flow can be corrected. To evaluate the system's performance, two image sets were used, one image set without side sway and another set with side sway. The comparison of their results showed very close with the error of around 6 %.