• Journal of KIISE:Software and Applications
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• v.36 no.11
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• pp.912-919
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• 2009

A novel algorithm using 2D tensor voting and edge-based approach is proposed for text detection in natural scene images. The tensor voting is used based on the fact that characters in a text line are usually close together on a smooth curve and therefore the tokens corresponding to centers of these characters have high curve saliency values. First, a suitable edge-based method is used to find all possible text regions. Since the false positive rate of text detection result generated from the edge-based method is high, 2D tensor voting is applied to remove false positives and find only text regions. The experimental results show that our method successfully detects text regions in many complex natural scene images.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.53-56
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• 2002

본 논문은 2채널 스피커를 사용하여 청취자에게 보다 입체적인 음향 효과를 제시하기 위하여 크로스토크현상을 제거하고 청취자의 보다 자유로운 청취를 위해 최적 청취영역 확대를 위한 실험과 시스템 구현에 관한 것이다. 정면에 위치한 두 스피커로부터 교차경로인 크로스토크를 제거하기 위해 음질의 왜곡을 최소화하는 자유음장 모델을 이용하여 구현한 트랜스오럴 필터 사용하였고 최적 청취영역의 확대를 위해 스피커는 BPF(Band Pass Filter)를 이용하여 저주파와 고주파를 분리하여 각각 재생할 수 있는 스피커를 구성하였으며 저주파 영역은 제외하고 중고주파 영역을 이용하였으며 기존 크로스토크제거 시스템을 사용하여 고정된 한 점의 청취영역에서 좌${\cdot}$우로 5Cm씩 이동하au 100Cm까지 측정한 결과 30Cm, 55Cm, 75Cm, 90Cm, 100Cm에서 크로스토크제거됨을 알 수 있는 음의 분리도가 5dB이상 나타났다. 실험 결과 얻어진 각 지점들로부터 자유음장 모델을 이용하여 트랜스오럴 필터링 하였으며 각각의 간섭현상을 막기 위해 주파수 영역에서 심리음향에 기초한 1/3-Octave Band Pass Filter를 사용하여 음질 보상을 실시하였다. 음원을 제작하여 기존의 2채널 시스템에서 제시하는 음원을 각각의 위치의 음원과 비교하여 음질 평가를 실시하였으며 기존의 트랜스오럴 필터와 비교평가를 실시하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.4
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• pp.256-262
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• 2004

A key component of an autonomous mobile robot is to localize itself and build a map of the environment simultaneously. In this paper, we propose a vision-based localization and mapping algorithm of mobile robot using fisheye lens. To acquire high-level features with scale invariance, a camera with fisheye lens facing toward to ceiling is attached to the robot. These features are used in mP building and localization. As a preprocessing, input image from fisheye lens is calibrated to remove radial distortion and then labeling and convex hull techniques are used to segment ceiling and wall region for the calibrated image. At the initial map building process, features we calculated for each segmented region and stored in map database. Features are continuously calculated for sequential input images and matched to the map. n some features are not matched, those features are added to the map. This map matching and updating process is continued until map building process is finished, Localization is used in map building process and searching the location of the robot on the map. The calculated features at the position of the robot are matched to the existing map to estimate the real position of the robot, and map building database is updated at the same time. By the proposed method, the elapsed time for map building is within 2 minutes for 50㎡ region, the positioning accuracy is ±13cm and the error about the positioning angle of the robot is ±3 degree for localization.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.31-37
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• 2004

We have proposed a design methodology for large active-area single-mode VCSELS, which have higher reliability and output power, and are well-suited for high-speed operation. The key idea underlying the design methodology is to reduce the effective index difference between active and cladding regions by controlling the thickness and position of the oxide layer. The idea is confirmed by the self-consistent effective index method. By placing the oxide layer position properly, we can increase the radius of the oxide aperture for single-mode operation by 3 times.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.9
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• pp.758-765
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• 2001

This paper proposes a method to automatically extract stable visual landmarks from sensory data. Given a 2D occupancy map, a mobile robot first extracts vertical line features which are distinct and on vertical planar surfaces, because they are expected to be observed reliably from various viewpoints. Since the feature information such as position and length includes uncertainty due to errors of vision and motion, the robot then reduces the uncertainty by matching the planar surface containing the features to the map. As a result, the robot obtains modeled stable visual landmarks from extracted features. This extraction process is performed on-line to adapt to an actual changes of lighting and scene depending on the robot’s view. Experimental results in various real scenes show the validity of the proposed method.

• The Journal of Society for e-Business Studies
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• v.16 no.3
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• pp.113-127
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• 2011

An RFID system has been widely applied in many areas over the initial SCM application. In the literature enormous RFID applications in healthcare are documented to improve patient safety, patient/provider logistics, and the efficiency of collecting data. Based on the proposed 4-layered RFID system architecture, we introduce a case that implemented an UHF passive RFID-based tracking system in an outpatient clinic. Particularly, we propose a method to process RFID data that contains noise and missing reads. The proposed method for processing unreliable RFID data is capable to locate the tag accurately and provide additional business information. We finally conclude the paper with identifying obstacles and what is necessary to ensure system reliability.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.3
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• pp.17-24
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• 2004

We present a P-type iterative learning control(ILC) scheme for uncertain robotic systems that perform the same tasks repetitively. The proposed ILC scheme comprises a linear feedback controller consisting of position error, and a feedforward and feedback teaming controller updated by current velocity error. As the learning iteration proceeds, the joint position and velocity mrs converge uniformly to zero. By adopting the learning gain dependent on the iteration number, we present joint position and velocity error bounds which converge at the arbitrarily tuned rate, and the joint position and velocity errors converge to zero in the iteration domain within the adopted error bounds. In contrast to other existing P-type ILC schemes, the proposed ILC scheme enables analysis and tuning of the convergence rate in the iteration domain by designing properly the learning gain.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.351-355
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• 1999

서비스 반경이 1이내인 마이크로셀 방식은 기지국의 송신출력을 가능한 작게 하고 안테나의 위치를 주변 건물의 높이보다 낮게 설치하기 때문에 셀 반경내에 있는 지형과 구조물들은 전파특성에 매우 큰 영향을 주므로 셀 내 지형지물의 특성에 따라 기지국의 최적 출력을 구할 수 있는 전파예측 모델이 필요하다. 본 연구에서는 이동국이 가시거리 영역의 전파 음영지역 또는 가시거리 영역과 일정 경사각으로 기울어져 있는 비가시거리 영역에 위치한 경우로 구분하고, 기지국으로부터 송신된 신호가 이동국까지 일정 직진경로를 전파하는 동안, 전파의 반사첫수와 전파경로를 계산할 수있는 연산처리 알고리즘을 개발하여, 이를 웅용하므로써 임의 지점에 위치한 이동국에 도래하는 수신전력을 예측할수 있는 모델을 제안한다. 그리고, 마이크로셀 이동통신 전파환경에서 개발 알고리즘과 제안 전파예측 모델을 시뮬레이션하여, 그 결과를 분석함으로써 마이크로셀 기지국의 최적 위치선정 조건과 기지국 출력에 따른 가입자 서비스 조건을 제시한다.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.8
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• pp.606-610
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• 2009

In Location-Based Service (LBS), a scheme to hide the exact locations of users is required for privacy protection, In this paper, we propose a grid-based cloaking method considering K-anonymity and L-diversity. For this, our method creates a minimum cloaking region by finding L number of buildings (L-diversity) and then finding number of users (K-anonymity). Especially, we use a effective filtering method for generating the minimum cloaking region in a fast way. Finally, we show from a performance analysis that our cloaking method outperforms the existing method, in terms of query processing time based on the size of cloaking regions.

• Journal of Korea Spatial Information System Society
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• v.6 no.2 s.12
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• pp.23-37
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• 2004

Location Based Services(LBSs) in mobile environments become very popular recently. For efficient LBSs, spatial database management systems must need a spatial indexing scheme such as R-trees in order to manage the huge spatial database. However, it may need unnecessary disk accesses since it needs to access objects which are not actually concerned to user's location-based queries. In this paper, to support the location-based queries efficiently, we propose a CLR-tree(Cell Leveling R-tree) in which a dynamic cell is built up within the minimum bounding rectangle of R-trees' node. The cell level of nodes is compared with the query's cell level in location-based query processing and determines the minimum search space. Also, we propose the insertion, split, deletion, and search algorithms for CRL-trees. From the experimental results, we see that a CLR-tree is able to decrease $5{\sim}20%$ of disk accesses from those of R-trees. So, a CLR-tree can be used for fast accessing spatial objects to user's location-based queries in LBSs.