• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.419-420
• /
• 2020

본 논문에서는 전자기 교반 시스템용 2 상 직교하는 전원 공급 장치의 출력 전류 정상상태 오차를 줄일 수 있는 제어 기법을 제안하다. 2 상 직교하는 전원 공급 장치는 단상 풀브리지 인버터 2 대 대신 3 상 전압원 인버터 1 대를 사용하여 인버터의 레그 숫자가 줄어들고 인버터 스위치의 도통 손실이 감소한다. 본 논문에서는 회전 좌표계로의 변환(dq 변환)을 통해 출력전류 정상상태 오차를 0 으로 제어하는 기법을 제안한다. 본 논문에서는 제안하는 제어 기법의 유효성은 시뮬레이션을 통해 검증하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.9
• /
• pp.1146-1149
• /
• 2014

To discriminate polarities of stator windings for 3 phase induction motors terminal tags of which are not readable, it is possible to utilize the residual magnetic flux present at their rotors as well as to use the way based on external exciting current. The induced voltages are basically decided by parameters such as the quantity of residual flux, the rotator speed by hand force and the phase properties between stator windings. To adopt induced voltages by residual flux for polarity discrimination at sites, the measured voltages by multi-testers need to be readable in magnitude enough to discriminate winding condition with reasonable phase characteristics. This study focuses on the analysis of various connection cases in the expectation that the summing voltages induced by residual flux shall show zero in case of normal connections while the sum becomes greater indication if the connection is in wrong condition. The proposed method is applied to actual motors to disclose how effective it is for polarity discrimination at sites through comparison of output signals between normal and fault connections.

• The Journal of the Petrological Society of Korea
• /
• v.9 no.4
• /
• pp.205-210
• /
• 2000

Measurements of phase identification and degree of orientation for fine-grained (about 0.3 mm in diameter) minerals in rock samples performed by micro-area X-ray diffractometer.$Al_{2}SiO_{5}$ polymorphs (andalusite, kyanite and sillimanite) were chosen for the measurements and target minerals were existed on thin sections. Micro-area X-ray diffractometer is composed of 3(${\omega}\;{\chi}\;{\phi}$)-circle oscillating goniometer and position sensitive proportional counter (PSPC). $CuK_{\alpha}$ radiation was used as X-ray source and a pin hole ($50\;\mu\textrm{m}$$ in diameter) collimator was selected to focus radiation X-ray onto the target minerals. Phase identification and diffracted X-ray peak indexing were carried out by 3(${\omega}\;{\chi}\;{\phi}$)-circle oscillation measurement. Then, 2(${\omega}\;{\phi}$)-circle oscillation measurement was made for the purpose of searching the prevailing lattice plane of the minerals on thin section surface. Finally, for a selected peak by 2-circle oscillation measurement, X-ray pole figure measurement was executed for the purpose of check the degree of orientation of the single lattice direction and examine its pole distribution. As a result of 3-circle oscillation measurement, it was possible that phase identification among $Al_{2}SiO_{5}$ polymorphs. And from the results of 2-circle oscillation measurement and X-ray pole figure measurement, we recognized that poles of andalusite (122), kyanite (200) and sillimanite (310) lattice plances were well developed with direction normal to each mineral surface plane respectively. Therfore, the measurements used with micro-area X-ray diffractometer in this study will be a useful tool of phase identification and degree of orientation measurement for fine-grained rock forming minerals.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2014.11a
• /
• pp.81-83
• /
• 2014

본 논문은 HD 해상도의 고화질 방송카메라(회전과 줌이 가능한)와 '키넥트' 같은 범용 모션인식 카메라를 연동하여 방송용 모션기반 증강현실 어플리케이션을 구현하기 위해서, 연기자의 위치를 가상 월드 좌표로 자동 변환시키는 방법을 제안한다. 방송환경에서 키넥트와 같은 모션인식카메라(RGB-D 카메라)를 사용하기 위해서는 거리와 조명의 영향을 많이 받아 연기자와 가까운 천장이나 카메라 밑처럼 그 설치 위치가 제약되곤 한다. 이때, 연기자와 그래픽의 정확한 합성을 위해, 모션인식 카메라로부터의 연기자 추적 정보를 월드 좌표계로 변환해야 하며, 이것을 수작업으로 하기에는 변환의 정확도가 많이 떨어지고 시간도 많이 소요된다. 본 논문에서는 체크박스 패턴 기반의 스테레오 카메라보정 알고리즘을 사용하여 모션인식카메라와 방송용 카메라간의 상관관계(이동, 회전)를 찾고, 이 값과 월드 좌표계 상의 방송 카메라(하드웨어 센서에 의해서 추적됨)정보(이동, 회전)를 이용하여 임의 위치에 설치한 모션인식 카메라로부터 추적된 연기자 위치정보를 월드 좌표계 상의 위치 값으로 자동 변환시키는 방법을 제안한다.

• Journal of Korea Multimedia Society
• /
• v.8 no.9
• /
• pp.1195-1207
• /
• 2005

In this paper, we describe image matching techniques which is automatically retrieving the exact matching area using geometry-phase information. We proposed a Matching Method which is rapidly estimating the correspondent points between adjacent images that included big-rotation and top-bottom movement element. It is a method that reduce computation quantity to be required to find an exact correspondent position using geometry-phase information of extracted points in images and DT map which set the distance value among feature points and other points on the basis of each feature point of a image. The proposed method shows good performance especially in the part to search a exact correspondent position between adjacent images that included big-rotation and top-bottom movement element.

• Korean Journal of Optics and Photonics
• /
• v.11 no.5
• /
• pp.371-376
• /
• 2000

For multi-hologram recording especially in a dIsk-shaped storage medium. we had studied a simple cost-effective method to unplement the rotational, angular, and ,patial multiplexmg techniques together in order to enhance the area storage density. Holographic storage with both rotational and angular multIplexing was realized by controlling the rderence beam directly with a pair of wedge prisms. whlie the storage WIth spatIal multlplexmg by shIfting the storage medium. In thIS paper \ve show that lhe area storage density of our system is strongly dependent on f numbers of the lenses in the srgnal and reference anns, and also show that the area storage densrly becollles maximal when the f number of the lens in the signal arm is approximately twice as long for a given f number of the lens in the reference emn. e emn.

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.1 no.2
• /
• pp.78-85
• /
• 2008

Purpose: The findings of preoperative magnetic resonance imaging (MRI) and ultrasonography (US) examination in the diagnosis of rotator cuff tear were then compared with the findings of arthroscopic examination, and to evaluate the postoperative integrity of rotator cuff using serial US examination. Methods: Between February and May 2008, 29 patients with rotator cuff tear had undergone preoperative US and MRI examination and subsequent arthroscopic examination. And the results of MRI and US were compared with intra-operative results of the arthroscopic examination. We observed the postoperative integrity of rotator cuff using serial (postoperative 2 weeks, 6 weeks, 3 months) US examination. Results: The sensitivity of US and MRI for identifying rotator cuff tear were 100% and 100%. The sensitivity of US and MRI were 95% and 82% in full thickness tear, and 50%, 33% in partial thickness tear, respectively. Overall accuracy of US and MRI were 86%, 69%. Among 22 patients were operated for full thickness tear, intra-operative gap formation was identified in 11 patients (50%, small to medium 2 cases, large to massive 9 cases) which were identified at 2 weeks postoperative US. We could find 5 re-tears (23%, small to medium 1 case, large to massive 4 cases) on 6 weeks postoperative US after passive range of motion (ROM) exercise, and could also find 7 re-tears (32%, small to medium 2 cases, large to massive 5 cases)on 3 months postoperative US after active ROM exercise. Conclusion: Serial US after arthroscopic rotator cuff repair was useful to differentiate intra-operative gap formation from postoperative re-tear. We found 5 retears (23%) at 6 weeks and 7 retears (32%) at 3 months postoperative US, it was useful to make treatment plan during postoperative rehabilitation.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.8
• /
• pp.88-100
• /
• 1999

Detecting human face and facial landmarks automatically in an image is as essential step to a fully automatic face recognition system. In this paper, we present a new approach to detect automatically face and its eyes of input image with scale and rotation variations of faces by using an intensity based template matching with a single log-polar face template. In a template-based matching it is necessary to normalize the scale changes and rotations of an input image to a template ones. The log-polar mapping which simulates space-variant human visual system converts scale changes and rotations of input image into constant horizontal and cyclic vertical shifts in the output plane. Intelligent use of this property allows us to shift of the candidate log-polar faces mapped at various fixation points of an input image to be matched to a template over the log-polar plane. Thus, the proposed method eliminates the need of adapting multitemplate and multiresolution schemes, which inevitably give rise to intensive computation involved to cope with scale and rotation variations of faces. Through this scale and rotation involved to cope with scale and method can lead to detecting face and its eyes simultaneously. Experimental results on a database of 795 images show over 98% detection rate.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.24 no.2
• /
• pp.123-128
• /
• 2014

This paper presents the study about MGV(Magnetic guidance vehicle) with up-and-down rotating type differential drive unit. Previous MGV needs the landmarks to get the driving information and additional sensor to recognize the landmarks except for localization sensor. Previous MGV requires at least 2 drive units when common fixed differential drive unit is used because it occurs the problems with driving control and localization error from imbalance of the MGV's weight. To solve such problems, we propose the MGV using up-and-down rotating type differential drive unit. Proposed MGV recognizes the driving information from the pattern which is consisted of both pole of magnet without landmarks and additional sensors, and it control the backward movement using up-and-down rotating type differential drive unit instead of common drive units. Proposed MGV considers KF(Kalman filter) to improve the localization accuracy. To verify the performance of proposed method, we designed MGV for the experiment. As the results, we can confirm the performance of propoesed method to recognize the pattern and to control the backward movement. With respect to localization, proposed method has the less RMSE about 5.6904 mm than previous method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1993.04b
• /
• pp.142-145
• /
• 1993

유정압베어링은 공기베어링과같은 유막의 평균화 효과를 얻을 수 있어 구성부품의 형상오차보다 우수한 회전정도를 기대 할 수 있으며 상대적으로 높은 강성, 부하용량 및 우수한 감쇠특성을 보유하고 있으면서도 비접촉에 의한 무보수, 반영구적 인 수명등의 장점이 있어 정밀도와 강성이 함께 요구되는 연삭기를 중심으로 공작기계 분야에 활발히 응용되고 있다. 본 연구에서는 고정밀도가 요구되는 연삭기용 유정압주축을 시작하고 정특성, 회전특성, 열특성등을 실험적으로 해석함으로서 실용화에 필요한 제변수들의 영향을 정량적으로 얻고자 하였다.