• The Journal of Korea Robotics Society
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• v.19 no.2
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• pp.149-158
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• 2024

This paper presents a robust autonomous navigation and reconnaissance system for tracked robots, designed to handle complex multi-floor indoor environments with stairs. We introduce a localization algorithm that adjusts scan matching parameters to robustly estimate positions and create maps in environments with scarce features, such as narrow rooms and staircases. Our system also features a path planning algorithm that calculates distance costs from surrounding obstacles, integrated with a specialized PID controller tuned to the robot's differential kinematics for collision-free navigation in confined spaces. The perception module leverages multi-image fusion and camera-LiDAR fusion to accurately detect and map the 3D positions of objects around the robot in real time. Through practical tests in real settings, we have verified that our system performs reliably. Based on this reliability, we expect that our research team's autonomous reconnaissance system will be practically utilized in actual disaster situations and environments that are difficult for humans to access, thereby making a significant contribution.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.174-182
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• 2013

The power wheelchair is an important and convenient mobility device. The demand of power wheelchair is increasing for assistance in mobility. In this paper we proposed a robotic wheelchair for mobility aid to reduce the burden from the disabled. The main issue in an autonomous wheelchair is the automatic detection and avoidance of obstacles and going to the pre-designated place. The proposed algorithm detects the obstacles and avoids them to drive the wheelchair to the desired place safely with panning scan from sensors of distance measurement and fuzzy control. By this way, the disabled will not always have to worry about paying deep attention to the surroundings and his path.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.216-220
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• 2008

오늘날 인터넷은 사용자에게 수많은 정보와 다양한 선택의 기회를 제공하지만, 사용자는 급속하게 늘어난 수 많은 정보 중에서 자신에게 유용한 정보를 찾는데 더 많은 시간을 투자해야만 한다. 이러한 문제점을 극복하고 좀 더 효율적인 인터페이스를 제공하기 위해서는 사용자들이 원하는 정보를 획득하기까지, 어떠한 탐색 과정을 거쳐 의사 결정을 내리는지에 관한 이해가 선행되어야 할 것이다. 따라서 본 연구는 웹 검색 결과를 소비하는 사용자의 정보 탐색 패턴과 이에 수반되는 인지 과정을 시선의 움직임을 통하여 분석하였다. 실험 결과 일반적인 글읽기 형태와는 차별된 시선의 움직임을 관찰할 수 있었는데, 대부분의 시선 이동 궤적은 직선이 아닌 도처에 걸쳐 흩어진 의미 단위로 드문드문 이동함을 알 수 있었다. 또한 각 의미 단위를 중심으로 진행성(forward) 도약과 역행성(regressive) 도약이 관찰되었고, 제목 ${\rightarrow}$ 내용 순의 세밀한 응시가 이루어진 이후 Click 여부가 결정되었다. 하지만 평균 Scan path 는 타이틀과 내용의 구분 없이 전체 화면 길이/너비의 50%를 넘지 못하여 축소된 Golden Triangle 형태를 보였다. 본 연구 결과는 웹 검색 결과에 대한 사용자 소비 경향의 특성을 파악하여 향후 좀 더 효율적인 소비를 이끌어내기 위한 인터페이스 설계 방향의 기초 연구로 그 의의가 있다.

• Laser Solutions
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• v.11 no.1
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• pp.25-31
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• 2008

The characteristics of femtosecond laser ablation of $Al_2O_3$ for prescision microfabrication are studied experimentally. Specifically, the process time during femtosecond laser drilling of microholes with $sub-100{\mu}m$ diameter are investigated for varying laser fluence, scan speed and beam path designs like trepanning with continuously changed start points. The accumulation of sub-micrometer size particles within the hole and the deterioration of edge clarity and roundness for decreasing hole diameter are examined and through process optimization the microdrilling with good hole quality is achieved using a femtosecond laser system (repetitionrate 1 kHz, wavelength 785 nm, pulse duration 185 fs)

• Korean Journal of Computational Design and Engineering
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• v.4 no.1
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• pp.60-68
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• 1999

In reverse engineering (RE) sustems, the quality of the data aquisition process is crucial to the accuracy of the reverse engineered three dimensional computer-aided design (CAD) model. However, these tasks are predominantly done manually, and little work has been done to improve the efficiency of scanning by determining the minimum number of scans and the optimal scanning directions. In this paper, new scanning and registration methods using tooling balls are developed to assist in determining the optimal parameter for these processes. When the object to scanned has no concavity, attaching path of the object and its bounding rectangle are used for optimal scanning and registration. Then minimum number of tooling balls and their positions are calculated automatically. In the case of concave parts, the scanning plan should include a complete scan of the concave area. With the surface normal vector and the scanning direction, the minimum degree of rotating the part can be calculated. But the maximum rotation should be restricted in order to prevent occlusion of the part. Finally tow sample part ar scanned based on the proposed methods and the results are discussed.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.1
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• pp.89-96
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• 2015

In this paper, it is studied that kinematic analysis of a 5-axis ultrasonic inspection equipment. The equipment is comprised of three straight axes and two rotary axes. With features of ultrasonic, the transmitter and receiver of the equipment are vertical to a test surface, operating at regular intervals. To perform this well, the motions of every link should be found on the based of kinematic analysis of the equipment. We chose starting point for testing and defined relations among all links through transformation of coordinates. For double curvature-shaped test object, we generated test paths. To follow these, we found motions of all links using inverse kinematics. By using Matlab/Simulink, simulator was developed, so that we could find out desired trajectories of main axes for a scan.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.46-52
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• 2016

We propose a new type of semi-global matching (SGM) in order to solve a streaking problem arising from conventional SGM. Conventional SGM imposes a penalty to a pixel when the disparity of the pixel differs from that of the previous pixel along a scan path, and thus, disparity changes are not easily allowed, causing the streaking effect. The road surface is an appropriate target for such an effect, because the colors of the surfaces are very similar, and the image pixels corresponding to the surfaces show disparities that change very smoothly along the viewing direction. In contrast to conventional SGM, the new type of SGM imposes penalties depending on the disparity gradients, and thus, the streaking effect is controlled. The experimental results show the effectiveness of the proposed SGM method.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.1
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• pp.37-45
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• 2009

The power wheelchair is an important and convenient mobility device. The demand of power wheelchair is increasing for assistance in mobility. In this paper we proposed a robotic wheelchair for mobility aid to reduce the burden from the disabled. The main issue in an autonomous wheelchair is the automatic detection and avoidance of obstacles and going to the pre-designated place. The proposed algorithm detects the obstacles and avoids them to drive the wheelchair to the desired place safely with panning scan from sensors of distance measurement and fuzzy control. By this way, the disabled will not always have to worry about paying deep attention to the surroundings and his path.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.323-326
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• 2001

We propose a new MUD adaptive beamforming algorithm. It requires no reference signal and consists of two Processing stages. The first stage performs a scan function, and the second stage performs an adaptive beamforming algorithm. Computer simulations, considering multi-path Rayleigh Fading Channel in CUMA, are presented to verify the performance.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.455-456
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• 2007

물체 식별은 감시 시스템에서 중요한 역할을 수행한다. 특히 사람/차 식별은 해당 사물의 존재 유무를 파악하기 위해 다양한 어플리케이션에서 사용된다. 우리는 외곽선 정보를 이용하여 빠르게 물체 식별을 할 수 있는 알고리즘을 제안한다. 감시 영상에서 움직이는 물체를 찾은 후, 외곽선 정보를 추출하여 미리 저장해 둔 사물의 모델과 비교하여 가장 가까운 거리값(유사도)을 찾는 방식이다. 2차원의 영상 처리에는 기본적으로 많은 연산량이 필요하지만, 주변 픽셀 정보를 최대한 유지할 수 있는 할버트 패스(Hilbert Path)를 사용하여 1차원의 배열로 변환한 후 비교하기 때문에 기존 알고리즘보다 빠르게 두 모델간의 유사도를 측정할 수 있다. 제안된 알고리즘은 사람/차 식별에 매우 강인한 성능을 보여주었으며, 기존 템플릿 매칭 기법보다 연산량의 감소로 실시간 감시 시스템에서 사용할 수 있을 것으로 기대된다.