• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2015년도 추계학술대회
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• pp.257-260
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• 2015

국적기의 사고 및 국내에서 발생한 사고를 분석해보면 많은 인명 피해가 발생된 사고의 유형들을 접할 수 있다. 운항중인 항공기에 특별한 결함이 없었음에도 불구하고 조종사의 잘못된 판단에 의한 사고는 선행연구들의 결과와 같이 많은 부분들을 차지하고 있다. 특히 비 정밀접근(Non Precision Approach)의 선회접근(Circling Approach) 및 시계접근(Visual Approach)절차에서 자주 발생되는 지상충돌 사례들을 과학적이고 객관적인 방법을 바탕으로 분석하여 유사사고 재발 방지를 위한 대안을 찾고자 한다. 이를 위해 조종사의 입장에서의 교육 및 절차에 관해 분석하여 비 정밀 접근 절차 수행의 기준을 제언하고자 한다.

• Journal of Korean Neurosurgical Society
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• 제48권3호
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• pp.213-218
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• 2010

Objective : Pituitary apoplexy (PA) is described as a clinical syndrome characterized by sudden headache, vomiting, visual impairment, and meningismus caused by rapid enlargement of a pituitary adenoma, We retrospectively analyzed the clinical presentation and surgical outcome in PA presenting with cranial neuropathy. Methods : Twelve cases (33%) of PA were retrospectively reviewed among 359 patients diagnosed with pituitary adenoma, The study included 6 males and 6 females, Mean age of patients was 49,0 years, with a range of 16 to 74 years, Follow-up duration ranged from 3 to 20 months, with an average of 12 months, All patients were submitted to surgery, using the transsphenoidal approach (TSA). Results : Symptoms included abrupt headache (11/12), decreased visual acuity (12/12), visual field defect (11/12), and cranial nerve palsy of the third (5/12) and sixth (2/12) Mean height of the mass was 29.0 mm (range 15-46) Duration between the ictus and operation ranged from 1 to 15 days (mean 7.0) The symptom duration before operation and the recovery period of cranial neuropathy correlated significantly (p = 0.0286) TSA resulted in improvement of decreased visual acuity in 91.6%, visual field defect in 54.5%, and cranial neuropathy in 100% at 3 months after surgery. Conclusion : PA is a rare event, complicating 3.3% in our series, Even in blindness following pituitary apoplexy cases, improvement of cranial neuropathy is possible if adequate management is initiated in time, Surgical decompression must be considered as soon as possible in cases with severe visual impairment or cranial neuropathy.

• 제어로봇시스템학회논문지
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• 제6권6호
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• pp.462-470
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• 2000

This paper proposes a visual servoing method based on QR decomposition and disturbance observer. The QR decomposition factors the image feature Jacobian into a unitary matrix and an upper triangular matrix. And it is shown that several performance indices such as measurement sensitivity of visual features, sensitivity of the control to noise and controllability can be improved for any general image feature Jacobian by QR decomposition and disturbance observer. To show the validity of the proposed approach, visual servoing with stereo vision is carried out for a Samsung FARAMAN 6-axis industrial robot manipulator.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1311-1316
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• 1999

A visual servoing method has been proposed based on disturbance observer to eliminate the effect of the off-diagonal component of image feature Jacobian, since performance indices such as measurement sensitivity of visual features, sensitivity of the control to noise and controllability could be improved when an image feature Jacobian was given as a block diagonal matrix. In this paper, experimental results of disturbance observer-based visual servoing are discussed where Samsung FARAMAN-AS1 6-axis industrial robot manipulator is employed. Also, the feature saturator is proposed to stabilize the disturbance observer loop by saturating the differential changes of the image features.

• 로봇학회논문지
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• 제1권2호
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• pp.125-134
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• 2006

The problem of establishing the servo system to reach the desired location keeping all features in the field of view and following a straight line is considered. In addition, robustness of camera calibration parameters is considered in this paper. The proposed approach is based on switching from position-based visual servoing (PBVS) to image-based visual servoing (IBVS) and allows the camera path to follow a straight line. To achieve the objective, a pose estimation method is required; the camera's target pose is estimated from the obtained images without the knowledge of the object. A switched control law moves the camera equipped to a robot end-effector near the desired location following a straight line in Cartesian space and then positions it to the desired pose with robustness to camera calibration error. Finally simulation results show the feasibility of the proposed visual servoing technique.

• 한국컴퓨터정보학회논문지
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• 제21권6호
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• pp.71-76
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• 2016

In this paper, we propose the mobile visual inspection information system using DGPS and portable range finder for levee safety inspection. Instead of existing visual inspection management method that is stored hand-written data, this system is designed to manage directly the visual inspection information using mobile devices in the field of levee. And through extracting accurate DGPS coordinates information about damage location of levee, this system is developed to ensure efficiency for the main task arising from the levee site such as inspection, maintenance and reinforcement. Furthermore, when damage has occurred at the point that inspector is not able to approach, this system can record the damage site data correctly, by converting data such as position, orientation and height of the damage point into the World Geodetic System coordinates. The position, orientation and height data was extracted automatically through the DGPS and portable range finder. And by applying the augmented reality method, this system was implemented for inspector to revisit the point of damage easily in order to perform the management, maintenance and reinforcement of the levee later.

• 한국정밀공학회지
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• 제20권10호
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• pp.82-88
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• 2003

Many visual servoing algorithms have been recently developed by the robot vision researchers. They do not, however, consider the stability of servoing system. The camera calibration is the most important factor to the control stability and performance of position based visual servoing. In this article we describe the ECL(End Point Closed Loop) servoing can make no steady state error for the control of 6-DOF robot of which accuracy is dependent on the camera calibration and kinematics. And we propose a dynamic calibration algorithm, which can improve stability and performance of ECL visual servoing. To verify the potential of our approach, we run assembly experiments and present our finding.

• 한국음향학회지
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• 제28권8호
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• pp.832-842
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• 2009

Automatic speech recognition (ASR) has been successfully applied to many real human computer interaction (HCI) applications; however, its performance tends to be significantly decreased under noisy environments. The invention of audio visual speech recognition (AVSR) using an acoustic signal and lip motion has recently attracted more attention due to its noise-robustness characteristic. In this paper, we describe our novel integration scheme for AVSR based on a late integration approach. Firstly, we introduce the robust reliability measurement for audio and visual modalities using model based information and signal based information. The model based sources measure the confusability of vocabulary while the signal is used to estimate the noise level. Secondly, the output probabilities of audio and visual speech recognizers are normalized respectively before applying the final integration step using normalized output space and estimated weights. We evaluate the performance of our proposed method via Korean isolated word recognition system. The experimental results demonstrate the effectiveness and feasibility of our proposed system compared to the conventional systems.

• 대한견주관절학회:학술대회논문집
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• 대한견주관절학회 2009년도 제17차 학술대회
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• pp.7-7
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• 2009

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
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• pp.159-164
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• 1999

Homogeneous but distinct visual objects having low-contrast boundaries are usually merged in most of the segmentation algorithms. To alleviate this problem, an efficient image segmentation algorithm based on a bottom-up approach is proposed by using spatial domain information only. For initial image segmentation, we adopt an efficient marker extraction algorithm conforming to the human visual system. Then, two region-merging algorithms are successively applied so that homogeneous visual objects can be represented as simple as possible without destroying low-contrast real boundaries among them. The resultant segmentation describes homogeneous visual objects with few regions while preserving semantic object shapes well. Finally, a size-based region decision procedure may be applied to represent complex visual objects simpler, if their precise semantic contents are not necessary. Experimental results show that the proposed image segmentation algorithm represents homogeneous visual objects with a few regions and describes complex visual objects with a marginal number of regions with well-preserved semantic object shapes.