• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1102-1105
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• 2004

In this paper, the problem of a viewer's head tracking in a desktop-based interactive stereoscopic display system is considered. A fast and low-cost approach to the problem is important for such a computing environment. The system under consideration utilizes a shuttle glass for stereoscopic display. The proposed method makes use of an image taken from a single low-cost video camera. By using a simple feature extraction algorithm, the obtained points corresponding to the image of the user-worn shuttle glass are used to estimate the glass center, its local 'yaw' angle, as measured with respect to the glass center, and its global 'yaw' angle as measured with respect to the camera location. With these estimations, the stereoscopic image synthetic program utilizes those values to interactively adjust the two-view stereoscopic image pair as displayed on a computer screen. The adjustment is carried out such that the so-obtained stereoscopic picture, when viewed from a current user position, provides a close-to-real perspective and depth perception. However, because the algorithm and device used are designed for fast computation, the estimation is typically not precise enough to provide a flicker-free interactive viewing. An error concealment method is thus proposed to alleviate the problem. This concealment method should be sufficient for applications that do not require a high degree of visual realism and interaction.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.559-564
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• 2008

A prediction of binary droplets collision is important in the formation of falling drops and the evolution of sprays. The droplet velocity, impact parameter and drop-size ratio have influence on the interaction of the droplets. By the effect of these parameter, the collision processes are generated with the complicated phenomena. The droplet collision can be classified into four interactions such as the bouncing, coalescence, reflexive separation and stretching separation. In this study, the two-phase flow of the droplet collision was simulated numerically by using the Level Set method. 2D axi-symmetric simulations on the head-on collisions in the coalescence and reflexive separation, and 3D simulation on the off-center collisions in the coalescence and stretching separation were performed. These numerical results showed good agreements with the experimental and analytical results. For tracking the identity of droplets after the collision, transport equation for the volume fraction of the each initial droplet were used. From this, the identities of droplets were analyzed on the collision of droplets having different size.

• 전자공학회논문지CI
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• 제38권6호
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• pp.46-56
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• 2001

본 논문에서는 연속적인 영상 정보와 자기 센서의 정보로부터 실시간으로 눈의 응시 방향을 추적하기 위한 효과적인 접근 방법에 대해 제안한다. 이러한 눈 응시 추적 시스템의 입력으로는 한 대의 카메라를 통해 얻어지는 영상들과 자기 센서의 데이터들이다. 눈의 영상을 받아들이는 카메라와 자기 센서의 수신부가 머리에 고정되어 있어서 측정된 데이터들은 눈과 머리의 움직임을 표현하는데 충분하다. 실험 결과에서는 제안한 시스템이 실시간으로 동작하는 측면에 대해 그 유용성을 보여줄 것이고 또 그러한 시스템을 이용하여 마우스 대신 새로운 컴퓨터 인터페이스로 사용할 수 있다는 가능성을 보여줄 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.65-69
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• 2004

The small form factor optical data storage devices are developing rapidly nowadays. Since it is designed for portable and compatibility with flash memory, its components such as disk, head, focusing actuator, and spindle motor should be assembled within 5 m thickness. The thickness of focusing actuator is within 2 mm and the total working range is $+/-100{\mu}m$, with the resolution of less than $1{\mu}m$. Since the thickness is limited tightly, it is hard to place the yoke that closes the magnetic circuit and hard to make strong flux density without yoke. Therefore, Halbach array is adopted to increase the magnetic flux of one side without yoke. The proposed Halbach array type focusing actuator has the advantage of thin actuation structure with sacrificing less flux density than conventional magnetic array. The optical head unit is moved on the swing arm type tracking actuator. Focusing coil is attached to swing arm, and Halbach magnet array is positioned at the bottom of deck along the tracking line, and focusing actuator exerts force by the Fleming's left hand rule. The working range and resolution of focusing actuator are analyzed with FEM and experiment.

• 한국HCI학회논문지
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• 제5권2호
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• pp.1-6
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• 2010

본 연구에서는 장애인이나 게이머를 위해 눈의 움직임과 머리의 움직임으로 제어가 가능한 헤드 마우스를 제안하였고, 제안한 마우스를 기존의 마우스와 비교하였다. 마우스 포인터의 이동은 머리 움직임의 회전각도 정보를 활용하였고, 클릭이나 더블 클릭의 이벤트는 눈의 깜빡임을 이용하였다. 기존의 각속도계를 이용한 마우스에서 적분으로 인한 누적오차는 적분을 하지 않고 데드 존을 갖는 비선형 상대 좌표계 방식을 통하여 해결하였고, 추가적으로 이동 거리와 가속도를 함께 고려하여 직관적인 마우스 포인터 제어가 가능하도록 하였다. 주변광의 영향을 최소화하도록 광원 제어 회로를 설계하여 외부 광원의 변화에도 마우스 이벤트 검출에 영향을 받지 않도록 하였다. 제안한 마우스를 응시점을 이용한 마우스(퀵글랜스)와 비교한 결과, 20회 클릭하는 실험에서는 약 21%, Dasher를 이용한 문자입력실험에서도 약 25%, 화상키보드를 이용한 문자입력 실험에서도 약 37% 짧은 입력 시간을 보였다. 그리고 카메라 마우스와의 비교에서도 제안한 헤드 마우스가 우수한 성능을 보였다.

• 한국정보통신학회논문지
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• 제18권5호
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• pp.1096-1102
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• 2014

적외선 조명을 이용한 간접시선추적 시스템에서는 촬영된 이미지에서 동공에 반사된 조명의 위치에 대한 캘리브레이션이 필수적이다. 하지만 안구의 크기나 머리의 위치에 따라 달라질 수도 있는 변수가 캘리브레이션 과정에서 정의된 상수로 계산에 포함되어 있어 오차를 감소시키는데 한계가 있다. 본 논문은 적외선 조명을 사용하면서도, 사용자 캘리브레이션 과정을 생략할 수 있는 방법을 연구한다. 반사각에 의한 글린트(glint)위치 차이에 영향을 받지 않게 하면서, 시스템의 모델과 시선 계산은 단순하게 하여 실시간 연산이 가능하도록 하는 것이 목표이다.

• 방송공학회논문지
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• 제14권4호
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• pp.419-427
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• 2009

본 논문에서는 시점의 움직임에 대해 최적의 자연스러운 스테레오 영상을 관찰자에게 제공할 수 있는 시점추적시스템을 제안하였다. 관찰자의 위치를 추적하기 위한 시점추적시스템은 관찰자와 배경의 상대적인 거리를 측정하여 배경으로부터 관찰자를 분리할 수 있다. 시점추적을 위한 키 신호를 얻는 방법으로 TOF(Time-Of-Flight) 이론으로 만들어진 깊이 카메라(depth camera)를 사용하였다. 또한 관찰자의 위치가 제한되는 고정형 패럴랙스배리어의 단점을 보완하는 방법으로 이동형 패럴랙스배리어를 제안하였다.

• Journal of Welding and Joining
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• 제18권4호
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• pp.70-75
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• 2000

The weld seam tracking system for arc welding process uses various kinds of sensors such as arc sensor, vision sensor, laser displacement and so on. Among the variety of sensors available, electro-magnetic sensor is one of the most useful methods especially in sheet metal butt-joint arc welding, primarily because it is hardly affected by the intense arc light and fume generated during the welding process, and also by the surface condition of weldments. In this study, a dual-electromagnetic sensor, which utilizes the induced current variation in the sensing coil due to the eddy current variation of the metal near the sensor, was developed for arc welding of sheet metal butt-joints. The dual-electromagnetic sensor thus detects the offset displacement of weld line from the center of sensor head even though there's no clearance in the joint. A set of design variables of the sensor were determined for the maximum sensing capability through the repeated experiments. Seam tracking is performed by correcting the position of sensor to the amount of offset displacement every sampling period. From the experimental results, the developed sensor showed the excellent capability of weld seam detection when the sensor to workpiece distance is near less than 5 mm, and it was revealed that the system has excellent seam tracking ability for the butt-joint of sheet metal.

• 센서학회지
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• 제23권2호
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• pp.82-86
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• 2014

This paper reports the development of a platform for tracking and analysis of animal locomotion. The platform is composed of a commercial webcam, a metal stand for the webcam, and a plastic bathtub as a cage. Using it, researchers can track and analyze an animal's movement within the plastic bathtub's dimensions of $100cm{\times}100cm{\times}55cm$ in a cost-effective manner. After recording the locomotion of an animal with $1920{\times}1080$ resolution at a rate of 30 frames per second, finding the position of the animal in each frame and analyzing the ambulation pattern were executed with custom software. To evaluate the performance of the platform, movements of imprinting control region mice and transgenic mice were recorded and analyzed. The analysis successfully compared velocity, moving pattern, and total moving distance for the two mouse groups. In addition, the developed platform can be used not only in simple motion analysis but also in various experimental conditions, such as a water maze, by easy customization of the platform. Such a simple and cost-effective platform yields a powerful tool for animal ambulatory analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권5호
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• pp.1856-1869
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• 2015

This paper addresses the issues of 3D human activity detection, tracking and recognition from RGB-D video sequences using a feature structured framework. During human tracking and activity recognition, initially, dense depth images are captured using depth camera. In order to track human silhouettes, we considered spatial/temporal continuity, constraints of human motion information and compute centroids of each activity based on chain coding mechanism and centroids point extraction. In body skin joints features, we estimate human body skin color to identify human body parts (i.e., head, hands, and feet) likely to extract joint points information. These joints points are further processed as feature extraction process including distance position features and centroid distance features. Lastly, self-organized maps are used to recognize different activities. Experimental results demonstrate that the proposed method is reliable and efficient in recognizing human poses at different realistic scenes. The proposed system should be applicable to different consumer application systems such as healthcare system, video surveillance system and indoor monitoring systems which track and recognize different activities of multiple users.