• 응용통계연구
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• 제28권3호
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• pp.485-494
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• 2015

정준대응분석은 생태학에서 장소, 종 그리고 환경변수의 관계를 시각적으로 보기 위해 가장 많이 사용되는 서열화 방법 중의 하나이다. 그런데 이 방법은 표본이 바뀔 때마다 분석결과가 달라지기 때문에 종 간의 생태학적 유사성에 대한 일관된 해석을 어렵게 한다. 본 연구에서는 이러한 문제점을 해결하기 위해 정준대응분석에 붓스트랩 방법을 활용하였다. 이를 통해 전체 관찰 자료수에 반비례하여 좌표점의 변이가 나타나고, 붓스트랩 신뢰구간을 사용한 포함확률이 명목확률에 근사함을 확인하였다.

• 대한기계학회논문집B
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• 제23권2호
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• pp.198-209
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• 1999

This study reports the selection of dependent variables for momentum equations in general curvilinear coordinates. Catesian, covariant and contravariant velocity components were examined for the dependent variable. The focus of present study is confined to staggered grid system Each dependent variable selected for momentum equations are tested for several flow fields. Results show that the selection of Cartesian and covariant velocity components intrinsically can not satisfy mass conservation of control volume unless additional converting processes ore used. Also, Cartesian component can only be used for the flow field in which main-flow direction does not change significantly. Convergence rate for the selection of covariant velocity component decreases quickly as with the increase of non-orthogonality of grid system. But the selection of contravariant velocity component reduces the total mass residual of discretized equations rapidly to the limit of machine accuracy and the solutions are insensitive to the main-flow direction.

• 한국의류산업학회지
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• 제12권5호
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• pp.582-590
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• 2010

Garment design needs an iterative manipulation of 2D patterns to generate a final sloper. Traditionally there have been two kinds of design methodologies such as the flat pattern method and the pattern draping method. But today, it is possible to combine the advantages from the two methods due to the realistic cloth simulation techniques. We devised a new garment design system which starts from 3D initial drape simulation result and then modifies the garment by editing the 2D flat patterns synchronously. With this interactive methodology using real-time pattern deformation technique, the designer can freely change a pattern shape by watching its 3D outlook in real-time. Also the final garment data were given relative coordinates with respect to the human anthropometric feature points detected by an automatic body feature detection algorithm. Using the relative human body coordinate system, the final garments can be re-used to an arbitrary body data without repositioning in the drape simulation. A female shirt was used for an example and a 3D body scan data was used for an illustration of the feature point detection algorithm.

• 한국운동역학회지
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• 제15권4호
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• pp.75-83
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• 2005

The purpose of this study was to determine the kinematic characteristics of the ankle joint and RPM(repetition per minutes) during the supra maximal training in cycling. For this study, 8 national representative cyclists, distance cyclists in track and road, were selected. During the super-maximum pedalling, kinematic data were collected using a six-camera(240Hz) Qualisys system. the room coordinate system was right-handed and fixed in the back of a roller for cycle, with right-handed orthogonal segment coordinate systems defined for the leg and foot. Lateral kinematic data were recorded at least for 3 minutes while the participants pedal on a roller. Two-dimensional Cartesian coordinates for each marker were determined at the time of recording using a nonlinear transformation technique. Coordinate data were low-pass filtered using a fourth-order Butterworth recursive filter with cutoff frequency of 15Hz. Variables analyzed in this study were compared using a one factor(time) ANOVA with repeated measures. The results of investigation suggest that the number of rotating pedal was decreased with time phase during the super-maximum pedaling. Maximum angle of the ankle joint showed little in change with time phase compared with minimum angle of that.

• 대기
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• 제21권3호
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• pp.243-256
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• 2011

This paper presents the development of new algorithm for identifying and tracking the convective cells in three dimensional reflectivity fields in Cartesian coordinates. First, the radar volume data in spherical coordinate system has been converted into Cartesian coordinate system by the bilinear interpolation. The three-dimensional convective cell has then been identified as a group of spatially consecutive grid points using reflectivity and volume thresholds. The tracking algorithm utilizes a fuzzy logic with four membership functions and their weights. The four fuzzy parameters of speed, area change ratio, reflectivity change ratio, and axis transformation ratio have been newly defined. In order to make their membership functions, the normalized frequency distributions are calculated using the pairs of manually matched cells in the consecutive radar reflectivity fields. The algorithms have been verified for two convective events in summer season. Results show that the algorithms have properly identified storm cells and tracked the same cells successively. The developed algorithms may provide useful short-term forecasting or nowcasting capability of convective storm cells and provide the statistical characteristics of severe weather.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.164-169
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• 2001

A comprehensive extension of functions and efficiency of the software system, DS/Block, developed earlier for the purpose of simulation of the motion of a ship block during lifting and turnover operation. A viewpoint change used in 3D-CAD is utilized and saves the time for displays of a series of configurations for the motion. The Euler parameters are adopted to convert 3 rotational degrees of freedom about global coordinate system to those about local coordinate system defined in Pro/ENGINEER. DS/Block provides FEM input data for stress and strain analyses. Several functions are incorporated for user-friendliness. DS/Block is to be tested and installed in a shipyard.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.193-194
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• 2017

This paper proposes a current control method in synchronous coordinate for vector control of PMSM (Permanent Magnet Synchronous Motor). In order to control the PMSM by MTPA(Maximum Torque per Ampere), it is necessary to generate the rotating magnetic field to be $90^{\circ}$ with the magnetic field of the rotor, and the current control is necessary. To apply the current control to PMSM, the phase of the current command is also changed in accordance with the change of the position of the motor rotor. In this paper, the control of PMSM is performed through simulation using DC current command in synchronous coordinate system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.609-610
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• 2006

As developing the information society, Lighting Emitted diode(LED) which is light source for illumination of next generation is attracted public attention. LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. So, many researches have continued in a illumination as LED module type. in this problem, heating problem is very important and difficult and that is caused in decreasing phenomenon of brightness and drift phenomenon of color coordinate. so the problem of heating is urgent question for illumination of LED. In this paper, structural design of PCB changed as two type for solving the heating problem. also the properties of heating is analysed and optical properties is measured with heating image camera and spectrometer according to change in this design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.2241-2242
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• 2006

As developing the information society, Lighting Emitted diode(LED) which is light source for illumination of next generation is attracted public attention. LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. So, many researches have continued in a illumination as LED module type. in this problem, heating problem is very important and difficult and that is caused in decreasing phenomenon of brightness and drift phenomenon of color coordinate. so the problem of heating is urgent question for illumination of LED. In this paper, structural design of PCB changed as two type for solving the heating problem. also the properties of heating is analysed and optical properties is measured with heating image camera and spectrometer according to change in this design.

• 한국환경과학회지
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• 제20권6호
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• pp.679-686
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• 2011

The characteristics of circulation in the coastal area of Jeju Harbor in Korea was examined using the Princeton Ocean Model(POM) with a sigma coordinate system. The result of numerical analysis well corresponded to the observed current data. The velocity at offshore was stronger compared to coastal area during the both period of in maximum flood and maximum ebb of spring tide. According to mean wind velocity, the tidal velocity at the shallow area of Jocheon was slightly increasing during maximum ebb. The effect of wind on the circulation was stronger in shallow area and showed rapid change with depth.