• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.5
• /
• pp.560-566
• /
• 2005

In this paper, a practical technique for correction of a distorted image for vision-based localization of ubiquitous mobile robot. The localization of mobile robot is essential and is realized by using camera vision system. In order to wide the view angle of camera, the vision system includes a fish-eye lens, which distorts the image. Because a mobile robot moves rapidly, the image processing should he fast to recognize the localization. Thus, we propose the practical correction technique for a distorted image, verify the Performance by experimental test.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.217-217
• /
• 2017

물 순환이란 물이 지표면으로부터 증발하거나 바다로부터 증발하여 습한 공기가 기단을 형성한 후 적합한 조건이 형성되면 강수를 초래하는 과정이라고 볼 수 있다. 여기서 강수는 여러 경로 즉, 증발산, 지표흐름, 침투, 침루 등을 통해 다시 순환과정을 거친다. 최근 도시화로 인한 불투수면적의 증가로 기후변화, 홍수지체시간 감소, 첨두 및 유출총량의 증가, 침투능 및 증발산량의 감소 등 자연하천의 유출특성과는 다른 유출특성이 나타나며, 물 순환 체계가 왜곡되어 지하수위는 낮아지고, 하천의 유량은 감소되는 등 하천의 정상적인 기능이 저하되고 있다. 이에 우리나라에서는 환경부 및 국토교통부 등 정부기관과 지방자치단체에서 법과 조례를 제정하여 저영향개발기법 (LID, Low Impact Development)을 적용하도록 권고하고 있으며 신도시 개발사업 시 왜곡된 도시의 물 순환체계를 개선하기 위하여 저영향개발기법을 적용하고 있다. 저영향개발 기법의 정량적인 효과를 검증하기 위해서는 미환경청 (U.S. EPA., United States Environmental Protection Agency)에서 개발한 SWMM모델을 이용하여야 한다. 본 연구에서는 도시화로 인해 왜곡된 물순환체계 개선을 위하여 다양하게 설계된 저영향개발기법의 정량적인 효율을 SWMM 모델을 통해 산정하고, 장기적인 측면에서 물순환 회복에 적합한 저영향개발기법의 배치 최적화를 제안하고자 한다.

• Ecology and Resilient Infrastructure
• /
• v.8 no.1
• /
• pp.1-8
• /
• 2021

A surface image velocimeter (SIV) measures the velocity of a particle group by calculating the intensity distribution of the particle group in two consecutive images of the water surface using a cross-correlation method. Therefore, to increase the accuracy of the flow velocity calculated by a SIV, it is important to accurately calculate the displacement of the particle group in the images. In other words, the change in the physical distance of the particle group in the two images to be analyzed must be accurately calculated. In the image of an actual river taken using a camera, camera lens distortion inevitably occurs, which affects the displacement calculation in the image. In this study, we analyzed the effect of camera lens distortion on the displacement calculation using a dense and uniformly spaced grid board. The results showed that the camera lens distortion gradually increased in the radial direction from the center of the image. The displacement calculation error reached 8.10% at the outer edge of the image and was within 5% at the center of the image. In the future, camera lens distortion correction can be applied to improve the accuracy of river surface flow rate measurements.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.4
• /
• pp.149-155
• /
• 2014

A study on the indoor positioning system has been active recently, and TDOA technique using acoustic signal has been used generally. The drawback of the TDOA is very weak against signal distortion due to multipath effect. Especially to estimate the smartphone position, the sound distortion is very severe, and the generated radio signal jitter when using WLAN or Bluetooth as a time reference signal makes the receiver difficult to estimate the position. In this paper, acoustic trigger signal for the receiver preparing the positioning signal reception is proposed, and the mitigation of the multipath effect is shown.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.39 no.6
• /
• pp.612-622
• /
• 2002

In this paper, we review temporal error concealment for video transport over unreliable networks, and a new approach for the recovery of lost or erroneous motion vection(MV)s by classifying the movements of neighboring blocks by their homogeneity is proposed. MVs of the neighboring blocks are classified according to the direction of MVs and a representative value for each class is determined to obtain the candidate MV set. By computing the distortion of the candidates, a MV with the minimum distortion is selected. Experimental results show that the proposed algorithm exhibits better performance in many cases than existing methods.

• The Journal of Aerospace Industry
• /
• s.70
• /
• pp.94-116
• /
• 2008

WTO는 범세계적 글로벌 경쟁상황에서 국가간 무역거래를 제한하고 자원배분을 왜곡하여 결과적으로 세계 후생의 감소를 가져오는 개별 국가들의 관세 및 각종 비관세장벽, 그리고 자원의 효율적 배분을 왜곡하는 각국 정부의 보조금 정책 시정을 위해 창설되었다. 항공기산업에 있어서 보조금 논쟁의 특징은 주로 선-선진국간 분쟁에 국한된다는 점에서 기존의 WTO에서 많은 갈등을 빚고 있는 선-후진국간의 분쟁과는 큰 차이가 있다. 한국이 주도적으로 대규모 개발사업을 추진하면서 정부보조금을 지급할 경우에는 장기적으로 보조금 분쟁에 휘말릴 가능성이 있다. 그러나 미국/유럽간 쌍무협정 체결 내용에서 보듯이 개발보조금 지급 비중이 전체 개발비의 33%이상이 되지 않을 경우는 큰 문제가 없을 것으로 예상되며, 추가적 지원이 필요할 경우에는 직접적 개발비 보다는 관련 지 원인프라 지원을 통해 특정성 문제를 회피할 필요가 있다. 또한 한국은 아직 WTO 민간 항공기 협정 미가입 상태이기 때문에 WTO로부터 당장 규제대상은 아니다. 실제로 WTO 회원 가입 절차는 WTO로부터 요청 후 국내 검토를 거쳐 예비회원가입(2년 소요)-정회원의 절차를 거치게 된다. 또한 보조금 지급에 의한 경쟁자의 산업 피해가 직접적으로 드러날 때까지는 더 많은 시간이 소요되기 때문에 실제로 WTO 제재를 받기까지는 상당한 시간을 확보할 수 있다. 그럼에도 불구하고 WTO 회원이 되면 항공기산업의 육성에 많은 제약이 따르므로 사전적으로 충분한 정부 지원을 통해 조속히 국제경쟁력을 키우는 전략이 필요한 것으로 보인다.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.5
• /
• pp.345-350
• /
• 2003

Acoustic intensity is usually estimated by the cross-spectrum of acoustic pressure at two adjacent microphones. The cross-spectrum calculated by digital Fourier transform technique will unavoidably have leakage error since the period of signal will not be usually coincident with record length. Therefore, the acoustic intensity estimated by the conventional FFT analyzer will show distorted value. In this paper, the expression of the Fourier transformed data of a harmonic signal with a single frequency is formulated when there is leakage error. The method to eliminate the effect of leakage error from the contaminated data is also proposed. Some numerical examples show the validation of the proposed method.

• The Journal of the Acoustical Society of Korea
• /
• v.25 no.4
• /
• pp.172-177
• /
• 2006

Various research and development on Synthetic Aperture Sonar technique is under way to enhance bearing resolution of a SONAR system. In this paper, we estimated perturbed array shapes, and compensated distortion by using estimated away shapes and synthesized arrays in aperture domain such as an ETAM technique. As experimental data, we used the one obtained from towed array in neighboring waters of the Korean peninsula. Through simulation on data where tow-ship speed is maintained at a constant level, we confirmed that synthesis effect of increasing SNR and narrowed beam width of main lobe was consistently demonstrated for about 1 minute when coherence of target signal was maintained. Also, we showed that the synthesis effect with respect to time was constantly maintained.

• The Journal of Korean Association of Computer Education
• /
• v.16 no.1
• /
• pp.51-61
• /
• 2013

This study is to investigate the effecting factors on using ICT ability, and using computers for learning through PISA 2009 Korean data. Multi-level analysis is adapted to hierarchical nested data. Results show as follows: First, using ICT ability is affected by variables on the student level, but not on the school level, except in ESCS. Second, using computers for the purpose of learning at home is also affected by variables on the student level, but not on the school level, except in ESCS and in the size of region. Third, using computers for learning at the school is more influenced by variables on the school level like ESCS, the size of region, the ratio of computers, and the student-teacher ratio. The results suggest planning a computer education policy with considering both personal and school differences based on the multi-level approach.

• The Journal of the Korea Contents Association
• /
• v.12 no.5
• /
• pp.478-487
• /
• 2012

The purpose of this paper is to investigate which the nature of teacher behavior affects the learning flow in the context of military education. Empirical results show that the leadership of the nature of teacher behavior has a significant effect on three factors of learning flow (flow experience, transformation of time, concentration on task). In addition, the pace of class of the nature of teacher behavior is significantly related to the transformation of time and the concentration on task, and the sense of humor of the nature of teacher behavior significantly affects the concentration on task. The findings provide practical implications on how a military education institution strategically employes the leadership, the sense of humor, and the pace of class in an attempt to select and train instructors.