• Journal of Korean Society for Geospatial Information Science
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• v.2 no.2 s.4
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• pp.143-151
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• 1994

3-D coordinates that result form GPS survey are not applied directly in korea because they are based on WGS 84 ellipsoid. Thus they must be transformed into longitude, latitude on the Bessel ellipsoid and orthometric height. Transformation parameters must be determined in order to perform the coordinate transformation. Also, coordinate transformation be preformed on longitude, latitude and ellipsoidal height. First estimation of Bessel geoidal height must be accomplished to acquire Bessel ellipsoidal height This paper suggests accuracy of coordinate transformation according to the estimation method of Bessel geoidal height. Also, This paper suggests that Bessel geoidal height have influence on the coordinates transformation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.351-357
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• 2011

In this study, we have intended to analyze the possibility of using the precise geoid model and to find the best geoid model for working by the airborne LiDAR system. So we have calculated the geoid height from the precise geoid models (KGEOID08, EGM2008, EIGEN-CG03C) and have analyzed results by comparing the geometric geoid height from surveying and geoid heights from geoid models. As a result, the KGEOID08 that had 0.152m of RMSE was assessed the best geoid model for making DEM(DTM) by airborne LiDAR system. Also we have found the needed arrangement and numbers of reference point when the KGEOID08 was used for conversion into orthometric height of LiDAR data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.1
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• pp.33-39
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• 1999

In order to calculate geoidal height refered to Bessel ellipsoid, methods to translate geoidal heights from a certain coordinate system to an arbitrary system with the corresponding ellipsoid are studied. and geoidal heights refered to Bessel ellipsoid were computed from EGM96 Model refered to GRS80 using iteration method pro-posed in this paper. Transformation parameters between WGS84 and Bessel were calculated using geoidal heights computed from iteration method. The result of coordinate transformation(standard deviation) were 0.009 second in latitude and 0.006 in longitude and 0.393m in orthometric height.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.13 no.2
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• pp.237-244
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• 1995

In this study, we made WGS84 geoidal height model from GPS measurements for bench marks and calculated geoidal height of B.Ms which were selected check points using the hi-linear, trend surface fitting and triangulation interpolation method. From these, the interpolation accuracy was studied. Also, we tried to study accuracy of height transformation by making up orthometric height with latitude and longitude on Bessel ellipsoid for bench marks which were calculated by applying transformation parameters that were got GPS measurements for precise primary control stations. As a result of this study, the WGS84 geoidal height and orthometric height could be determined as a deviation value of 20 cm.

• Proceedings of the KIEE Conference
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• summer
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• pp.1510-1512
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• 2004

본 연구는 농형 유도 발전기와 양방향 PWM 인버터를 가진 WECS (Wind Energy Conversion System)시스템을 모델링하고 이 모델에 기초하여 제어 법칙을 제안하였다. 제어 법칙은 풍속 따라 작용하는 최적 팁 속도비에 의해 효율이 최대가 되도록 제어하는 것이다. WECS은 바람의 변동이 있어도 최적치에 팁 속도비를 유지하기 위해 터빈의 회전 속도 제어하여 행한다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.221-227
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• 2002

This paper deals with the mechanical stress analysis due to electromagnetic forces and the optimal design of the link considering the stress. The link in Interior Permanent Magnet Brushless Motor(IPM) have influence on both mechanical and magnetic performance. The decrease of the link thickness serves to improve the torque, whereas this decreases the strength of link. Therefore, it is necessary to determine the appropriate link thickness considering electromagnetic forces and thermal expansion. The effects of the variation of link thickness on the mechanical stress and the electromagnetic performance are analyzed by the structural and electromagnetic Finite Element Method. In addition, the mechanical structure design of the link is performed to reinforce the mechanical strength against magnetic forces while preserving a food magnetic torque.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.228-233
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• 2002

A computational method for analysis of the 3 dimensional electro-magnetic induction problems has been developed. The developed method is capable of modeling the induced current and analyzing its characteristics using only scalar Potential at each node. A benchmark model of asymmetrical conductor with a hole is analyzed to verify the application of the developed method. The calculated value of magnetic flux density are compared with the measured value, and the results indicate that the developed method is valid. Also, Comparing with 3-D finite element method (FEM) results, we conformed effectiveness of the developed method for the accuracy and computation times.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.6
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• pp.262-270
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• 2003

In this paper, the characteristics of single-phase line-start permanent magnet synchronous motor driven by constant voltage are analyzed on d-q axis vector diagram and compared with that of current controlled motor. The coupled method of symmetrical coordinates and d-q axis voltage equation are applied to the analysis method like the analysis of single-phase induction motor. From the result of the analysis, it is seen that motors driven by constant voltage source have effects on not only the amplitude of current and torque but also current and current phase angle, so overall characteristics such as power factor and load angle are affected by circuit parameters. For precise analysis and design of single-phase line-start synchronous motor, its characteristics should be analyzed on d-q axis vector plan in consideration of the variation of circuit parameters.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.5
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• pp.295-304
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• 2004

This paper deals with characteristic analysis method using d-q axis equivalent circuit considering iron loss in a single-phase line-start permanent magnet synchronous motor. The iron loss resistance to account for the iron loss is included in the equivalent circuit to improve the modeling accuracy. Furthermore, for the improved calculation of the iron loss, the iron loss is calculated from the magnetic flux density by 2-dimensional finite element method. The result is represented as the iron loss resistance and connected in parallel with the total induced voltage. Therefore, the currents can be expressed as the summation the output current with the current corresponding to the iron loss. Finally, the steady state characteristic analysis results are compared with the experimental results to verify this approach.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1179-1180
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• 2011

본 논문은 재생에너지의 고전압크기 변환에 적용하기 위해 출력 정류 다이오드 뒤에 LCL 공진회로를 갖는 푸시풀 컨버터를 나타내었다. 푸시풀 컨버터의 공진회로는 두 배의 스위칭 주파로 동작함으로 공진요소의 값이 작아도 되어 소형 경량이다. 제안된 푸시풀 컨버터 토포로지는 낮은 전압에서 높은 전압까지 안정된 전압을 얻을 수 있다. 실험 컨버터는 입력전압 24[V], 전류 80-A, 출력전압 320[V] 출력 1.5[kW]이고 동작 주파수 20 [kHz]에서 양호하게 동작하였고 시뮬레이션과 실험 결과가 잘 일치함을 볼 수 있다.